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Purpose: To evaluate the influence of patellar morphology on functional outcomes and patellofemoral joint alignment after unicompartmental knee arthroplasty (UKA)., Methods: This study retrospectively analyzed the clinical and imaging data of 207 patients with osteoarthritis of the unicompartment of the knee who underwent UKA between September 2020 and April 2023. Patients were divided into three groups according to the Wiberg classification: group W1 (I, n = 47), group W2 (II, n = 117), and group W3 (III, n = 43). Knee function was assessed using the Hospital for Specialty Surgery (HSS) knee score and Feller patellar score, and the incidence of anterior knee pain after surgery was recorded and compared. Imaging parameters such as patellar tilt angle (PTA), lateral patellofemoral angle (LPA) and Insall-Salvati ratio (ISR) were measured to assess patellofemoral joint alignment., Results: The HSS scores of the three groups were not statistically different; the postoperative Feller scores of the group W3 differed significantly from those of the other two groups. The incidence of early postoperative anterior knee pain was higher in the group W3 than in the other two groups. The difference between preoperative PTA, postoperative PTA and preoperative LPA in the group W3 and the other two groups was statistically significant., Conclusion: Patients with Wiberg III patellae exhibited worse patellar scores, as well as more anterior knee pain and patellar tilt postoperatively. This finding highlights the need for individualized treatment to the Wiberg III patella during UKA to enhance surgical outcomes., Competing Interests: Declarations Ethics approval This study was approved by the Ethics Committee of the Affiliated Hospital of Xuzhou Medical University (Ethics Approval Number: XYFY2023-KL350-01). Informed consent All patients signed informed consent to allow further scientific analysis using their anonymised data. Consent for publication All the authors have reviewed and confirmed the accuracy of the whole manuscript. Conflict of interest On behalf of all authors, the corresponding author states that there is no conflict of interest., (© 2024. The Author(s) under exclusive licence to SICOT aisbl.)

Purpose: The purpose of this study was to compare postoperative patellar tilt at 4 months follow-up in a consecutive series of randomised patients that received individualised or off-the-shelf (OTS) primary total knee arthroplasty (TKA). The hypothesis was that patellar tilt would be lower and less variable in patients who received individualised TKA compared to patients who received OTS TKA., Methods: A consecutive series of 385 patients randomised (1:1) to receive either OTS TKA or individualised TKA were analysed. Pre- and postoperative radiographs at 4 months were obtained of weight-bearing long leg, anterior-posterior and lateral knee views and a skyline view at 30° of flexion. Postoperative patellar tilt was measured between the anterior femoral line and patellar resection surface (β) and the anterior femoral line and mediolateral patellar axis (σ). Postoperative patellar tilt (absolute value) was compared between the individualised and OTS TKA groups based on preoperative phenotypes of their femoral mechanical angle, tibial mechanical angle and hip-knee-ankle angle. Variability in postoperative patellar tilt was compared using the 95% confidence intervals (CIs)., Results: Comparisons of baseline patient characteristics revealed no difference between the individualised and OTS TKA groups. Comparison of absolute postoperative patellar tilt revealed significant differences between individualised and OTS TKA (|β|, 1.0° ± 1.0° and 2.5° ± 2.2°, respectively, p < 0.001; |σ|, 1.7° ± 1.6° and 2.8° ± 2.3°, respectively, p < 0.001). The 95% CI of postoperative patellar tilt (|β|) was narrower in patients that received individualised compared to OTS TKA (0.0° to 3.8° and 0.1° to 8.3°, respectively), irrespective of their preoperative phenotype., Conclusion: Patients who underwent individualised TKA had lower and less variable postoperative patellar tilt than those with OTS TKA, irrespective of preoperative phenotype. Individualised TKA allows the decoupling of the tibiofemoral and patellofemoral joints, replicating anatomical trochlear orientation and improving patellar tilt, which could facilitate better clinical outcomes., Clinical Trial Registration: This study constitutes a part of a larger registered randomised controlled trial comparing patient satisfaction following OTS versus individualised TKA (NCT04460989)., Level of Evidence: Level II., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Advances in computer hardware and software permit the reconstruction of physical objects digitally from digital camera images. Given the varying shapes and sizes of human bones, a comprehensive assessment is required to establish the accuracy of digital bone reconstructions from three-dimensional (3D) photogrammetry. Five human bones (femur, radius, scapula, vertebra, patella) were marked with pencil, to establish between 9 and 29 landmarks. The distances between landmarks were measured from the physical bones and digitized from 3D reconstructions. Images used for reconstructions were taken on two separate days, allowing for repeatability to be established. In comparison to physical measurements, the mean (±standard deviation) absolute differences were between 0.2±0.1mm and 0.4±0.2mm. The mean (±standard deviation) absolute differences between reconstructions were between 0.3±<0.1mm and 0.4±0.4mm. The 3D photogrammetry procedures described are accurate and repeatable, permitting quantitative analyses to be conducted from digital reconstructions. Moreover, 3D photogrammetry may be used to capture and preserve anatomical materials for anatomy education., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

With an incidence of approximately 42 per 100,000 persons annually, patellar instability is a debilitating condition that can result in dysfunction of the normal patellar tracking and potential cartilage damage. The stability of the patellofemoral (PF) joint involves an intricate relationship between muscular forces, soft tissues, trochlear and patellar geometry, and limb alignment. Several anatomic patellar risk factors (APRFs) have been identified including patella alta (Caton Deschamps >1.2; Insall-Salvati >1.2), rotational malalignment (femoral anteversion >30°, knee rotation >10°, and tibial rotation >35°), genu valgum (Valgus: zone 2 or greater), a lateralized tibial tubercle (tibial tubercle-trochlear grove distance >17 mm; tibial tubercle-posterior cruciate ligament distance >21 mm), and trochlear dysplasia. The importance of APRFs is highlighted by their overwhelming association with patellar instability; >80% of patients with patellar instability have at least 1 risk factor. Biomechanically, these risk factors increase lateralizing forces on the patella, increase maltracking (patellar tilt and subluxation), decrease contact area, and increase pressure in the PF joint. In addition, there is greater anisometry of the medial PF ligament reconstruction. Clinically, the presence of APRFs increases the chances of recurrence after a first episode as well as failure rates of medial PF ligament reconstruction. Initially described by Dejour on lateral radiographs, current APRF evaluation includes standard radiographs along with axial slice imaging, with magnetic resonance imaging being more commonly used currently. In some instances, mechanical axis radiographic views and axial computed tomography rotational alignment studies may be indicated. Each risk factor can be assessed independently, as there are good-quality studies defining abnormal thresholds for individual APRF. However, there is a lack of robust clinical data defining use of these thresholds for guiding decisions regarding nonsurgical/surgical treatment, specifically, which factors need to be surgically managed and at what threshold for optimal outcomes. It is important to understand that there is an intricate and complex interaction between risk factors that need to be considered during PF evaluation. Overall, evaluation of APRF is one of the core elements of PF instability management., Competing Interests: Disclosures The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: E.A.A. reports a relationship with International Society of Arthroscopy Knee Surgery and Orthopaedic Sports Medicine that includes: board membership. All other authors (A.J.O., B.B.H.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Background: In primary total knee arthroplasty (TKA) surgeries, the medial parapatellar (MP) and subvastus (SV) approaches are frequently employed. The SV approach involves preserving the vastus medialis muscle, leading to debates about the possibility of earlier healing of the extensor mechanism. Shear wave elastography (SWE) is known for monitoring tissue healing. In this study, our research question revolves around whether there exist differences in tissue healing following MP and SV approaches. Unlike previous studies, we aim to investigate this difference using solely SWE, which provides a quantitative measurement specifically targeting the vastus medialis muscle., Methods: We divided 17 patients into two groups: SV (10 patients) and MP (7 patients). SWE measurements and clinical scores were recorded before surgery and at the 3rd-month follow-up. The first straight leg raising days were also recorded., Results: Both the MP and SV groups showed significant improvement in clinical scores postoperatively. Straight leg raising time was comparatively earlier in the SV group, but no significant difference was found. SWE measurements revealed similar recovery values in the vastus medialis muscle between the two groups., Conclusion: Both MP and SV approaches demonstrate similar and favorable early outcomes in TKA surgery. The preservation of the vastus medialis in the SV approach does not lead to significant differences in clinical scores or muscle recovery compared to the MP approach., Trial Registration: The study was retrospectively registered on ClinicalTrials.gov on March 7, 2024 (NCT06297746). https://classic., Clinicaltrials: gov/ct2/show/NCT06297746?id=am7mi3VB&draw=2&rank=1 ., Competing Interests: Declarations. Ethical approval: This study was performed following the principles of the Declaration of Helsinki. The study protocol was approved by the Istanbul University - Cerrahpaşa, Clinical Research Ethics Committee (Application code: am7mi3VB). Informed consent: Informed consent was obtained from all individual participants included in the study. Permission to publish was obtained from all participants. Conflict of interest: All authors declare that they have no conflict of interest., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: The purpose of our study is to describe a magnetic resonance imaging quantitative parameter to assess the morphology of the trochlea that could be measurable from normal to high-grade trochlear dysplasia while evaluating the most proximal slice with trochlear cartilage., Methods: Two groups of patients have been compared: patients with no patellofemoral pain, no previous trauma and undergoing surgery for a suspected isolated meniscal tears (group A) and patients with objective patellar instability (group B). The cranial trochlear orientation (CTO) angle is defined as the angle between the posterior bicondylar line and the most lateral and most medial points on the subchondral bone covered by cartilage digitised on the first and most cranial image with the trochlear cartilage clearly visible., Results: The final cohort included 253 patients (109 in group A and 144 in group B). CTO was significantly higher in group B (-2.5 ± 8.4 vs. -10.8 ± 5,1; p < .001). Moreover, 75% of knees in group B had a CTO > -7°, while 75% of knees in group A had a CTO < -7°. CTO was measurable in all 253 knees, whereas the lateral trochlear inclination and the sulcus angle were measurable in only 202 knees. The entire cohort was also divided into knees with CTO ≤ 0° and CTO > 0°. All knees with a CTO > 0 were in group B, and 49% of knees with CTO < 0 were in group B. CTO was positively correlated with lateral patellar tilt., Conclusions: CTO is the only parameter that can be measured on the most cranial slice, in every patient, even in high-grade trochlear dysplasia. According to this new system, the axial trochlear shape may be divided into two types: a positive CTO and a negative CTO, with the trochlea serving, respectively, as a medial and lateral barrier., Level of Evidence: Level III., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Introduction: With a satisfaction rate of 80%, total knee arthroplasty (TKA) surgery has seen significant improvements in recent decades. The 20% of poor results may be explained by the alignment technique used for implant placement, which can influence patellofemoral kinematics. The objective of this study was to demonstrate that the use of inverse kinematic alignment makes it possible to obtain satisfactory clinical and radiological patellar scores in robotic TKA., Hypothesis: The inverse kinematic alignment technique coupled with robotic surgery makes it possible to restore the native kinematics of the patella., Materials and Methods: This prospective study including 100 TKAs with a primary TKA performed using the Stryker Mako™ robotic surgery system, and the inverse kinematic alignment technique. Patients who underwent patella resurfacing were excluded. Clinical and radiological scores were recorded preoperatively and 1 year postoperatively., Results: At one year, the specific patellar clinical scores were excellent with an average Kujala score of 85.69 and an average HSS Patellar score 88.15. The average patellar lateralization index was 0.15 and the average patellar tilt was 5.1°, showing no significant difference compared to preoperation (p=0.45 and p=0.18). The average external rotation of the femoral implant was 0.47±0.6° [-1.9; 2.1]., Discussion: The patellofemoral clinical results were excellent. The use of the robotic arm coupled with this alignment technique makes it possible to obtain a controlled external rotation of the femoral implant as well as an optimized orientation of the tibial component, favoring good restitution of the alignment of the extensor apparatus. This study did not demonstrate any radiological correction of patellar tilt and lateralization., Conclusion: The combined use of robotic surgery with the inverse kinematic alignment technique seems effective on specific clinical results of the patellofemoral joint., Level of Evidence: II; prospective cohort., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Background: Medial open-wedge high tibial osteotomy (OWHTO) is performed for isolated medial compartment osteoarthritis or osteonecrosis of the knee and correction of varus deformity of the full lower extremity. OWHTO may induce sagittal parameter changes, including these in the tibial posterior slope (TPS), patellar height (PH), and patellofemoral joint problems. This study aimed to identify radiographic parameters associated with patellofemoral cartilage damage after OWHTO., Hypothesis: The patellofemoral joint cartilage worsens after OWHTO and is adversely affected by PH changes., Patients and Methods: Twenty patients (25 knees) who underwent primary OWHTO and subsequent implant removal surgery, including second-look arthroscopy for evaluation of the patellofemoral cartilage condition were enrolled. The patients were received 12 to 35 months of postoperative follow-up, and categorized into two groups according to whether patellofemoral cartilage damage worsened. TPS and PH parameters, including the Insall-Salvati, Blackburne-Peel, Caton-Deschamps, and modified Blumensaat (MBI) indices, were measured on lateral knee radiographs. The hip-knee-ankle and medial proximal tibial angles were measured using an anteroposterior radiograph of the full lower extremity. The extent of change from preoperative to postoperative (Δ) was calculated for all indices., Results: Eleven knees (44%) had worsening cartilage conditions in the femoral trochlear groove, with>1-degree of deterioration in the International Cartilage Repair Society grade. The radiographic measure for predicting patellofemoral cartilage deterioration was ΔMBI (95% confidence interval [CI]: 3.53×10 -14 -0.812, p=0.047). PF cartilage damage tended to progress in ΔMBI<-0.145. The postoperative TPS and HKAA in patients with deterioration in patellofemoral cartilage damage was greater than that in patients without deterioration in patellofemoral cartilage damage (p=0.037 and 0.038, respectively)., Discussion: The patellofemoral cartilage damage tends to progress after OWHTO. ΔMBI is a factor for predicting worsening patellofemoral cartilage condition. However, attention should be paid to the excessive posterior slope as high TPS and valgus alignment as valgus HKAA because intraoperative control of MBI is impossible., Level of Evidence: IV, retrospective study., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Objective: Patellofemoral osteoarthritis (OA) may be more common in females than males. Reasons for this are not fully understood, but sex differences in patellar morphology may help explain this phenomenon. We quantified differences in patellar morphology between males and females in healthy and patellofemoral OA populations., Design: A total of 97 (50F, 47M) healthy and 67 (40F, 27M) OA knees were scanned via computed tomography. OA individuals were on a waitlist for total knee replacement. Patella 3D models were segmented and 2D measurements were recorded: patellar width and height, lateral and medial facet width, and surface area. Medial and lateral facet surface topography was mapped using 81 points to describe 3D articular surface shape. Sex and group differences were assessed using Procrustes analysis of variance (ANOVA). Data were ordinated using Principal Component Analysis., Results: Differences in patellar 2D measurements between healthy and OA individuals were smaller than were differences between males and females from healthy and OA groups. Sex and healthy/OA differences were most pronounced for medial facet shape, which featured a posteriorly-curving facet and taller, narrower facet shape in males compared to females. Lateral facet shape variance was higher in OA cohorts compared to healthy groups., Conclusions: Medial and lateral facet shapes showed different patterning of variation by sex and healthy/OA status. Lateral facet shape may be of interest in future models of OA risk in the patellofemoral joint, here showing increased magnitudes of variance associated with increased severity of disease (patellofemoral Kellgren and Lawrence score)., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: To investigate whether the patellotrochlear index (PTI) predicts patella alta as determined by tibial-based methods of Insall-Salvati (IS) and Caton-Deschamp (CDI) indexes in a pathological population (with patellofemoral pain and/or instability), in addition to determining whether PTI and sagittal patellofemoral engagement (SPE) correlate with trochlea length as determined by lateral condyle index (LCI)., Methods: Patients with confirmed patella alta (IS/CDI ratio >1.2) undergoing tibial tubercle osteotomy for patellofemoral pain/instability with an available magnetic resonance imaging (MRI) scans were included. Patients who had undergone previous soft-tissue realignment, previous surgery, or trauma to the extensor mechanism were excluded. Two raters measured the IS, CDI, PTI, SPE, LCI, and knee flexion angle (KFA) on MRI. Interobserver reliability and correlation between measurements were calculated., Results: In total, 71 knees were included. PTI (0.73), SPE (0.836), LCI (0.701), and KFA (0.8) demonstrated good- to near-excellent interobserver reliability. IS (0.65) and CDI (0.66) demonstrated moderate interobserver reliability. PTI and SPE showed the strongest significant correlation (0.8112, P = 2.2 × 10 -16 ). IS and CD (0.39, P = .0007) showed a moderate significant correlation. PTI and KFA (0.53, P = 1.685 × 10 -6 ) and SPE and KFA (0.61, P = 1.991 × 10 -8 ) had a significant moderate correlation. LCI and KFA (-0.37, P = .0017) showed a significant moderate negative correlation. All other measurement indices correlated poorly and were insignificant. A total of 94.4% of the knees were defined as having patella alta using IS, with the remaining 5.6% having a raised CDI. Only 14% of cases had an IS of >1.2, a CDI >1.2, and a PTI <0.125, which increased to 39% (28/71) when the threshold for PTI was increased to <0.28., Conclusions: There was no correlation between tibial (IS and CD) and femoral methods (PTI and SPE) of quantifying patella alta. PTI and SPE did not correlate with trochlea length as measured by LCI. PTI, SPE, and LCI are significantly affected by the KFA during MRI., Level of Evidence: Level IV, retrospective diagnostic radiographic investigation., Competing Interests: Disclosures The authors report the following potential conflicts of interest or sources of funding: M.H. was funded by a full scholarship [ID: NMJ10/20] from the Ministry of Higher Education of the Arab Republic of Egypt for 1-year clinical research fellowship at the Royal Orthopaedic Hospital, UK. All other authors (M.S., N.S., L.R.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Full ICMJE author disclosure forms are available for this article online, as supplementary material., (Copyright © 2024 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Aims: Knee osteoarthritis (KOA) is a common degenerative joint disease characterized by pain and functional limitations. Current treatments offer symptomatic relief but do not address the underlying pathology. This study explores the role of the infrapatellar fat pad (IFP) in KOA and evaluates the efficacy of its partial arthroscopic excision., Methods: A retrospective review was conducted on 37 KOA patients who underwent partial IFP excision. Pain and function were assessed using the WOMAC and VAS scores, while MRI evaluations focused on cartilage health., Results: Significant postoperative improvements were observed in both pain and functional outcomes, with substantial reductions in WOMAC and VAS scores (P < 0.001). MRI findings demonstrated notable enhancements in cartilage integrity, reflected in significantly improved WORMS scores (P < 0.001)., Conclusions: Partial excision of the IFP significantly reduces pain and improves function in KOA patients, while also promoting cartilage health. These findings support the IFP's role in KOA pathology and highlight the potential benefits of targeted surgical intervention., (© 2024. The Author(s).)

Background: Total knee arthroplasty (TKA) is a common surgical procedure for patients with knee osteoarthritis. The patellar component plays a crucial role in knee biomechanics and can influence postoperative outcomes. This study aimed to investigate the relationship between radiological indices of patellar height and patient outcomes following TKA., Methods: A retrospective analysis was conducted on patients who underwent TKA for osteoarthritis. Radiographic measurements of patellar height, including the Insall-Salvati (IS) ratio, modified Blackburne-Peel (mBP) ratio, Caton-Deschamps ratio, and plateau-patellar angle (PPA), were obtained. Clinical outcomes were assessed using the Knee Society Score (KSS) and the Forgotten Joint Score-12 (FJS-12). Patient satisfaction and postoperative complications were also evaluated. Statistical analyses, including correlation analysis and multiple regression models, were performed to determine the association between radiological indices and patient outcomes., Results: The study included 330 cases that met the inclusion criteria. The analysis revealed significant correlations between different radiological indices of patellar height and patient outcomes. Lower postoperative PPA was correlated with worse KSS and range of motion scores. A decreased mBP ratio was associated with poorer FJS-12 responses and higher risks of dissatisfaction and patellar clunk or crepitus. Increased IS ratio was linked to a lower likelihood of incidental giving way of the knee. Advanced age was associated with reduced dissatisfaction and incidental giving way probabilities., Conclusions: The findings of this study demonstrate that radiological indices of patellar height can predict patient outcomes following TKA. Assessing patellar height using various radiographic measurements provides valuable information for surgical planning and prognostic evaluation. Understanding the impact of patellar height on clinical outcomes can aid in optimizing TKA procedures and improving patient satisfaction. These findings emphasize the importance of considering patellar height as a predictive factor in TKA and highlight its potential role in guiding postoperative management and rehabilitation strategies., Competing Interests: CONFLICT OF INTEREST: No potential conflict of interest relevant to this article was reported., (Copyright © 2024 by The Korean Orthopaedic Association.)

Objectives: The aim of this study is to evaluate the relationship between the achievement of clinically significant improvement in patient-reported outcome measures (PROMs) and the postoperative magnetic resonance image (MRI) appearance of matrix-associated chondrocyte implantation (MACI), in conjunction with patellofemoral realignment procedures, for the treatment of grade-IV chondral defects about the patellofemoral joint., Methods: A retrospective review of patients undergoing MACI for grade-IV chondral defects of the patella or trochlea by a single sports-medicine-fellowship-trained surgeon from 2017 to 2020 was performed. Concomitant realignment procedures, including tibial tubercle osteotomy and medial patellofemoral ligament reconstruction, were also performed as needed. Patients with preoperative and minimum 1-year postoperative PROMs and postoperative knee MRI were included. MRI scans were obtained at 6.3 (interquartile range: 5.8, 7.5) months postoperatively. A fellowship-trained musculoskeletal radiologist assigned a Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score (range: 0-100, with 100 equating to complete graft healing) to each MRI. Achievement of the minimal clinically important difference (MCID) for International Knee Documentation Committee (IKDC), Knee Injury and Osteoarthritis Score-Quality of Life, and Kujala scores were determined for each patient. Paired t-tests or Wilcoxon rank-sum tests were used to evaluate for an association between achievement of the MCID for each PROM and MOCART score. The average follow-up time and time from surgery to PROMs were 2.7 ​± ​1.5 years and 1.7 ​± ​0.66 years, respectively., Results: Thirty patients were included. There was a significant improvement in all PROMs from preoperative to postoperative (p ​< ​0.001). More than two-thirds of patients achieved the MCID for each PROM. Patients who achieved the MCID for IKDC had significantly higher MOCART scores (66.5 ​± ​16.2) than those who did not meet the MCID for IKDC (50.6 ​± ​23.6, p ​= ​0.043)., Conclusion: MACI for the treatment of patellofemoral chondral injuries is associated with clinically significant improvement in PROMs at short-term follow-up. Clinically significant improvements in IKDC scores are associated with a more mature MRI appearance of the autologous chondrocyte implantation graft on postoperative MRI, as indicated by higher MOCART scores., Level of Evidence: IV-Case Series., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Sabrina Strickland reports a relationship with Smith and Nephew Inc that includes consulting or advisory, speaking and lecture fees, and travel reimbursement. Sabrina Strickland reports a relationship with Vericel Corporation that includes consulting or advisory and speaking and lecture fees. Additional disclosures for senior author SS: Pacira Therapeutics, Inc. Food and Beverage Smith ​+ ​Nephew, Inc. Food and Beverage ORGANOGENESIS INC. Food and Beverage Engage Uni, LLC Gift DePuy Synthes Sales Inc. Food and Beverage Miach Orthopedics, Inc. Food and Beverage Bioventus LLC Food and Beverage Linvatec Corporation Food and Beverage Miach Orthopaedics Inc. Consulting Fees. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Andreas Gomoll reports a relationship with Vericel Corporation that includes consulting or advisory fees. Andreas Gomoll reports a relationship with Bioventus LLC that includes consulting or advisory fees. Andreas Gomoll reports a relationship with Organogenesis, Inc that includes consulting or advisory fees. Andreas Gomoll reports a relationship with Smith and Nephew Inc that includes consulting or advisory fees. Andreas Gomoll reports a relationship with Joint Restoration Foundation, Inc that includes consulting or advisory fees. Andreas Gomoll reports a relationship with Flexion Therapeutics, Inc that includes consulting or advisory fees. Andreas Gomoll receives hospitality payments from the following Bioventus, LLC, Organogenesis, Inc, Smith and Newphew Inc, Pacira Therapeutics, Flexion Therapeutics, Inc, Aesculap Biologics, LLC. Andreas Gomoll receives payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events for the following: Pacira Therapeutics, Linvatec Corporation, Fidia Pharma USA Inc. Andreas Gomoll has royalty or license for Organogenesis, Inc, and Moximed, Inc., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Objective: Patellar height changes after tibial tubercle osteotomy (TTO) have not yet been described. We aimed to evaluate whether TTO ± medial patellofemoral ligament reconstruction (MPFL-R) influences patellar height and tendon length, hypothesizing that TTO would decrease patellar height and tendon length., Methods: A retrospective review was performed of skeletally mature adolescents (<18 y) receiving primary anteromedialization or medialization TTO ± MPFL-R. Patients with at least 6 months of radiographic follow-up were included in the study. Pre and postoperative patellar heights were assessed on lateral, weight-bearing, and flexion (30 to 70 degrees) radiographs using the Blackburne-Peel Index (BPI), Caton-Deschamps Index (CDI), and Insall-Salvati Ratio (ISR). Subgroup analyses were performed to compare patellar height changes in patients with preoperative patella alta, norma, and baja, as well as between patients undergoing medialization and anteromedialization TTO. Data were analyzed for normality using a Shapiro-Wilk test, and paired-sample t tests were performed., Results: Forty-nine knees were included (mean age: 15 y; range: 12 to 17). A significant decrease in mean patellar height after TTO ± MPFL-R was observed across all measures: BPI (0.12, P = 0.000783), CDI (0.08, P = 0.01062), and ISR (0.15, P = 0.00000075). Patellar tendon length decreased by 2.26 mm ( P = 0.001272). Subgroup analyses demonstrated a decrease in mean patellar height across all 3 measurements ( P < 0.001; BPI, CDI, and ISR) for patients with preoperative patella alta but not patella norma or baja. Additional subgroup analysis showed a patellar height decrease using BPI (0.15, P = 0.004583) and ISR (0.14, P = 0.0002806) for patients receiving medialization TTO but not anteromedialization. The anteromedialization cohort did not demonstrate patellar height change using BPI and CDI; ISR demonstrated a decrease (0.10, P = 0.00917)., Conclusions: Mean patellar height and tendon length decreases after TTO ± MPFL-R in skeletally mature, adolescent patients. Subgroup analyses suggest these changes occur in patients with preoperative patella alta and/or patients who undergo medialization TTO. These data suggest that some distalization in patellar positioning may be achieved without formal distalization osteotomy., Competing Interests: J.J.E. is a paid consultant for Johnson & Johnson. T.G.M. is a paid consultant for Arthrex, Inc. S.K.A. is a paid consultant for Stryker. The remaining authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To elucidate the local microcirculation of the infrapatellar fat pad (IFP) in patients with knee osteoarthritis (KOA) by determining the changes in IFP hardness and hemoglobin concentration during isometric quadriceps exercise (IQE)., Design: In this observational cross-sectional study, patients diagnosed with bilateral KOA were included in the KOA group (30 knees), healthy older adults in the control group (20 knees), and younger adults in the young group (20 knees). Ultrasonography was performed at rest and during IQE to measure IFP hardness based on shear wave velocity. Near-infrared spectroscopy was performed to measure oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and total hemoglobin (cHb) in the IFP before (Baseline), during (IQE task), and after IQE (Post). IFP hardness and O2Hb, HHb, and cHb concentration were analyzed using a linear mixed model for the groups and measurement points., Results: During IQE, IFP hardness changes were significantly less in the KOA group than in the other groups (KOA: 95 % confidence intervals (CIs) [-0.854, 0.028]; control: 95 % CI [-0.941, -0.341]; and young: 95 % CI [-2.305, -1.706]). In the KOA group, O2Hb concentration exhibited no significant changes at Post compared with Baseline; however, significant changes were observed in the other groups (KOA: 95 % CI [-1.176, 0.423]; control: 95 % CI [-1.452, -0.276]; and young: 95 % CI [-4.062, -2.102])., Conclusions: During IQE, changes in hardness and hemoglobin concentration in the IFP were not significant in the KOA group, suggesting impaired local microcirculation of the IFP., Competing Interests: Declaration of Competing Interest There are no conflicts of interest to declare for the authors., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Multipartite patella is an anatomical variant classified by the fragmentation of the main patellar body. The cause of this variant is due to failure in fusion of the patellar ossification centers. It is commonly misdiagnosed as a fracture of the patella in clinical practice, leading to unnecessary treatment measures. The aim of this review is to provide an overview of the development and classification of this variation, diagnostic imaging techniques, and assess the optimal management technique for the symptomatic patient. Multiple radiographic methods are used to identify this variant, with recent studies highlighting high sensitivity rates for nonradiative methods (ultrasound). In terms of symptomatic management, accessory fragment excision and vastus lateralis release provide the greatest alleviation of symptoms, with screw fixation being less favorable., (© 2023 The Authors. Clinical Anatomy published by Wiley Periodicals LLC on behalf of American Association of Clinical Anatomists and British Association of Clinical Anatomists.)

Purpose: The J-sign is a clinical evaluation tool that assesses for patellar maltracking and is considered positive if lateral translation of the patella in extension, in the pattern of an inverted J is observed. This study aims to determine the association of clinical J-sign with imaging features noted on dynamic kinematic computed tomography (DKCT)., Methods: A retrospective review was conducted by reviewing the clinical records of all patients aged 18 years or younger who had a CT patellar tracking scan done between 1 January 2005 to 31 December 2016 in a single institution. Patients who had the presence or absence of a 'J-sign' evaluated clinically were included. Radiographic parameters evaluated using the axial cuts include the patellar tilt angle, congruence angle, Dejour's classification, femoral sulcus angle, trochlear groove depth, and Wiberg's classification. Patients were then divided into two groups based on the presence or absence of J-sign on clinical examination. The radiographic measurements were then analyzed for association with the presence or absence of J-sign on clinical examination., Results: Patients with a positive J-sign had an increased patellar tilt of 23.3° ± 14.2° and an increased congruence angle of 47.1° ± 28.5° when measured in extension as compared to a patellar tilt of 18.3° ± 10.8° and a congruence angle of 32.1° ± 20.8° in patients with a negative J-sign ( p  = 0.024 and 0.004, respectively). Comparisons of the change in congruence angles with the knee in full extension and at 20° flexion also yielded significantly higher change of 28.0° ± 20.4° in patients with a positive J-sign as compared to 11.9° ± 17.5° in patients with a negative J-sign. Patients with a positive J-sign also had an increased TT-TG distance of 17.6 ± 5.6 mm as compared to a TT-TG distance of 14.7 ± 6.9 mm in patients with a negative J-sign ( p  = 0.01)., Conclusion: Patients with a positive J-sign had an increased patellar tilt and an increased congruence angle when measured in extension. Increased TT-TG distance was also significantly associated with positive J-sign. Patients with a positive J-sign also had a greater change in their congruence angle when measured with the knee in full extension and at 20° of flexion.

This study aimed to analyse the growth plate fusion and secondary ossification centres of the hind limbs in maned wolves (Chrysocyon brachyurus) using radiographs. Data from three maned wolves estimated to be 3-4 months old were utilised. The right and left hind limbs were radiographed in the mediolateral and craniocaudal views once a month until 11-12 months of age and then every 2-3 months until 18-19 months of age. The growth plates identified in the hind limbs and their closure times were as follows: proximal femur (13-15 months), distal femur (13-15 months), proximal tibia (17-19 months), tibial tuberosity (17-19 months), distal tibia (11-13 months), proximal fibula (13-15 months) and calcaneal tuber (8-9 months). Measurements of the areas of the secondary ossification centres of the proximal epiphysis of the femur, distal epiphysis of the tibia, patella and fibular tarsal bone epiphysis showed a significant difference between the first assessment and 6-7 months. The distal femoral epiphysis, proximal tibial epiphysis and tibial tuberosity showed a statistically significant difference between the first assessment and 7-8 months. The difference in the proximal epiphysis of the fibula was observed between 4 to 5 months and 7 to 8 months. In conclusion, the information obtained regarding the growth plates and secondary ossification centres of the maned wolves may support other studies and help understand the normal patterns of the species., (© 2024 Wiley‐VCH GmbH. Published by John Wiley & Sons Ltd.)

Objective: Ultrasound therapy effectively treats a joint range of motion limitation and pain originating from soft tissue in knee osteoarthritis (OA). Few interventional studies have focused on the infrapatellar fat pad (IFP), and the effects of high-intensity continuous ultrasound (HICUS) on IFP stiffness and gliding have not been investigated. Therefore, we aimed to determine the effects of HICUS on IFP stiffness and gliding., Methods: This single-blind, randomized, controlled crossover study involved 24 healthy participants. The HICUS and placebo conditions were applied to the knee joint on 2 different days. HICUS was performed (1 MHz, 2.5 W/cm², duty cycle 100%, 5 min) using an ultrasound machine equipped with an applicator and adsorption-type fixed automatic rotation irradiation function. The main outcomes were IFP stiffness and gliding measured at 10 degrees and 120 degrees knee flexion. Gliding was measured as the difference between the patellar-tendon tibial angles at 10 degrees and 120 degrees knee flexion. Measurements were performed before (T1), immediately after (T2), and 15 min after (T3) treatment., Results: Two-way repeated measures analysis of variance showed a significant interaction of IFP stiffness at 10 degrees knee flexion; post-test results showed that HICUS decreased stiffness at T2 and T3. There was no significant difference at 120 degrees. A significant interaction of gliding was observed under the HICUS condition. Post-tests showed that HICUS significantly improved gliding at T2 and T3., Conclusion: HICUS is a simple, safe intervention for improving IFP stiffness and gliding in healthy participants, with sustained effects. Further studies are needed to evaluate its efficacy in patients., Competing Interests: Conflict of interest The authors declare no competing interests., (Copyright © 2024 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Background and Objectives : This study aimed to evaluate the tibial tubercle-posterior intercondylar eminence (TT-IC) distance as a diagnostic tool and surgical guide for correcting extensor apparatus misalignment through tibial tubercle osteotomy. Materials and Methods : A retrospective analysis was conducted on patients with extensor apparatus misalignment. The TT-IC distance was measured using MRI. Patients underwent tibial tubercle osteotomy, guided by the TT-IC distance for correction. Post-operative outcomes, including alignment, pain scores, and functional recovery, were assessed. Results : A significant correlation was found between the TT-IC distance and the degree of extensor apparatus misalignment. Utilizing the TT-IC distance as a surgical guide led to improved alignment in majority of patients. Post-operative outcomes showed reduced pain and enhanced functional recovery. Conclusions : The study established the TT-IC measurement as a valuable tool for determining the need for tibial tuberosity osteotomy in patients with patellar instability, particularly those with trochlear dysplasia, by providing a more precise criterion than the traditional TT-TG distance.

Background: Patellar instability is a well-known pathology in which kinematics can be investigated using metrics such as tibial tuberosity tracheal groove (TTTG), the bisect offset (BO), and the lateral patellar tilt (LPT). We used dynamic computed tomography (CT) to investigate the patellar motion of healthy subjects in weight-bearing conditions to provide normative values for TTTG, BO, and LPT, as well as to define whether BO and LPT are affected by the morphology of the trochlear groove., Methods: Dynamic scanning was used to acquire images during weight-bearing in 21 adult healthy volunteers. TTTG, BO, and LPT metrics were computed between 0° and 30° of knee flexion. Sulcus angle, sulcus depth, and lateral trochlear inclination were calculated and used with the TTTG for simple linear regression models., Results: All metrics gradually decreased during eccentric movement (TTTG, -6.9 mm; BO, -12.6%; LPT, -4.3°). No significant differences were observed between eccentric and concentric phases at any flexion angle for all metrics. Linear regression between kinematic metrics towards full extension showed a moderate fit between BO and TTTG (R 2 0.60, β 1.75) and BO and LPT (R 2 0.59, β 1.49), and a low fit between TTTG and LPT (R 2 0.38, β 0.53). A high impact of the TTTG distance over BO was shown in male participants (R 2 0.71, β 1.89) and patella alta individuals (R 2 0.55, β 1.91)., Conclusion: We provided preliminary normative values of three common metrics during weight-bearing dynamic CT and showed the substantial impact of lateralisation of the patella tendon over patella displacement., Relevance Statement: These normative values can be used by clinicians when evaluating knee patients using TTTG, BO, and LPT metrics. The lateralisation of the patellar tendon in subjects with patella alta or in males significantly impacts the lateral displacement of the patella., Key Points: Trochlear groove morphology had no substantial impact on motion prediction. The lateralisation of the patellar tendon seems a strong predictor of lateral displacement of the patella in male participants. Participants with patella alta displayed a strong fit between the patellar lateral displacement and tilt. TTTG, BO, and LPT decreased during concentric movement. Concentric and eccentric phases did not show differences for all metrics., (© 2024. The Author(s).)

Objectives: To develop and validate a deep learning-based approach to automatically measure the patellofemoral instability (PFI) indices related to patellar height and trochlear dysplasia in knee magnetic resonance imaging (MRI) scans., Methods: A total of 763 knee MRI slices from 95 patients were included in the study, and 3393 anatomical landmarks were annotated for measuring sulcus angle (SA), trochlear facet asymmetry (TFA), trochlear groove depth (TGD) and lateral trochlear inclination (LTI) to assess trochlear dysplasia, and Insall-Salvati index (ISI), modified Insall-Salvati index (MISI), Caton Deschamps index (CDI) and patellotrochlear index (PTI) to assess patellar height. A U-Net based network was implemented to predict the landmarks' locations. The successful detection rate (SDR) and the mean absolute error (MAE) evaluation metrics were used to evaluate the performance of the network. The intraclass correlation coefficient (ICC) was also used to evaluate the reliability of the proposed framework to measure the mentioned PFI indices., Results: The developed models achieved good accuracy in predicting the landmarks' locations, with a maximum value for the MAE of 1.38 ± 0.76 mm. The results show that LTI, TGD, ISI, CDI and PTI can be measured with excellent reliability (ICC > 0.9), and SA, TFA and MISI can be measured with good reliability (ICC > 0.75), with the proposed framework., Conclusions: This study proposes a reliable approach with promising applicability for automatic patellar height and trochlear dysplasia assessment, assisting the radiologists in their clinical practice., Clinical Relevance Statement: The objective knee landmarks detection on MRI images provided by artificial intelligence may improve the reproducibility and reliability of the imaging evaluation of trochlear anatomy and patellar height, assisting radiologists in their clinical practice in the patellofemoral instability assessment., Key Points: • Imaging evaluation of patellofemoral instability is subjective and vulnerable to substantial intra and interobserver variability. • Patellar height and trochlear dysplasia are reliably assessed in MRI by means of artificial intelligence (AI). • The developed AI framework provides an objective evaluation of patellar height and trochlear dysplasia enhancing the clinical practice of the radiologists., (© 2024. The Author(s).)

Periarticular knee fractures, which include fractures of the distal femur, tibial plateau, and patella, account for 5%-10% of musculoskeletal injuries encountered in trauma centers and emergency rooms. These injuries are frequently complex, with articular surface involvement. Surgical principles center on reconstruction of the articular surface as well as restoration of limb length, alignment, and rotation to reestablish functional knee biomechanics. Fixation principles are guided by fracture morphology, and thus, CT with multiplanar reformats and volume rendering is routinely used to help plan surgical intervention. Fractures involving the distal femur, tibial plateau, and patella have distinct management considerations. This comprehensive CT primer of periarticular knee fractures promotes succinct and clinically relevant reporting as well as optimized communication with orthopedic trauma surgeon colleagues by tying fracture type and key CT findings with surgical decision making. Fracture patterns are presented within commonly employed fracture classification systems, rooted in specific biomechanical principles. Fracture typing of distal femur fractures and patellar fractures is performed using Arbeitsgemeinschaft für Osteosynthesefragen/Orthopedic Trauma Association (AO/OTA) classification schemes. Tibial plateau fractures are graded using the Schatzker system, informed by a newer explicitly CT-based three-column concept. For each anatomic region, the fracture pattern helps determine the surgical access required, whether bone grafting is warranted, and the choice of hardware that achieves suitable functional outcomes while minimizing the risk of articular collapse and accelerated osteoarthritis. Emphasis is also placed on recognizing bony avulsive patterns that suggest ligament injury to help guide stress testing in the early acute period. © RSNA, 2024 Supplemental material is available for this article.

Background: Anterior knee pain (AKP) following total knee arthroplasty (TKA) with patellar preservation is a common complication that significantly affects patients' quality of life. This study aimed to develop a machine-learning model to predict the likelihood of developing AKP after TKA using radiological variables., Methods: A cohort of 131 anterior stabilized TKA cases (105 patients) without patellar resurfacing was included. Patients underwent a follow-up evaluation with a minimum 1-year follow-up. The primary outcome was AKP, and radiological measurements were used as predictor variables. There were 2 observers who made the radiological measurement, which included lower limb dysmetria, joint space, and coronal, sagittal, and axial alignment. Machine-learning models were applied to predict AKP. The best-performing model was selected based on accuracy, precision, sensitivity, specificity, and Kappa statistics. Python 3.11 with Pandas and PyCaret libraries were used for analysis., Results: A total of 35 TKA had AKP (26.7%). Patient-reported outcomes were significantly better in the patients who did not have AKP. The Gradient Boosting Classifier performed best for both observers, achieving an area under the curve of 0.9261 and 0.9164, respectively. The mechanical tibial slope was the most important variable for predicting AKP. The Shapley test indicated that high/low mechanical tibial slope, a shorter operated leg, a valgus coronal alignment, and excessive patellar tilt increased AKP risk., Conclusions: The results suggest that global alignment, including sagittal, coronal, and axial alignment, is relevant in predicting AKP after TKA. These findings provide valuable insights for optimizing TKA outcomes and reducing the incidence of AKP., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Osteochondral fractures (OCF) are traumatic shearing injuries to portions of cartilage and bone. The most common cause is patellar dislocation, with the main localisation being the medial patellar facet and the lateral femoral condyle. They can occur in all age groups., Diagnosis: Clinically, there is a painful knee joint effusion (haemarthrosis) with a "dancing patella". This is usually accompanied by restricted movement and/or a locking phenomenon. In addition to the standard X‑ray of the knee in three planes (lateral, anterior-posterior and tangential patella), an MRI should be performed promptly in the case of haemarthrosis and suspicious symptoms, as concomitant injuries are present in up to 70% of cases., Treatment: The aim of treatment is to restore joint congruence in order to prevent the risk of secondary osteoarthritis. Small chondral and stable osteochondral fractures can be treated conservatively. Surgery is indicated for all other OCFs. In addition to refixation with various materials (bioresorbable screws, bone plugs, suture material and Kirschner wires), cartilage regeneration procedures (AMIC, MACI, OAT, etc.) are available for late diagnosed or non-refixable fragments. However, the number of cases is small., Conclusion: Osteochondral fractures are rare injuries in children and adolescents. Prompt MRI is recommended for diagnosis in cases of suspected OCF. Refixation is the preferred treatment method, with bioresorbable implants showing promising results in reducing the need for additional surgery. The risk of secondary osteoarthritis can be reduced with regular treatment., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Patellar tuberculosis (TB) is a rare manifestation of musculoskeletal tuberculosis, accounting for a small proportion of cases. This case report presents a detailed analysis of a female patient in her early 30s who presented with isolated TB of the patella without concurrent pulmonary involvement. The patient received antitubercular chemotherapy, consisting of a 4-month intensive phase followed by an 8-month continuation phase. This case report underscores the rarity and diagnostic complexities associated with patellar TB. The condition often presents with non-specific symptoms, often mimicking prepatellar bursitis, necessitating a high level of clinical suspicion, particularly in patients from the endemic areas. Radiographic imaging and histopathological examination play crucial roles in establishing an accurate diagnosis. Antitubercular chemotherapy forms the cornerstone of treatment while surgical intervention is reserved for cases of extensive bone destruction or treatment failure., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Case: A 38-year-old woman presented to our clinic with right knee pain and difficulty ambulating. After cultures were obtained, a cryptococcal infection of the patella was identified. Subsequent workup revealed previously undiagnosed HIV/AIDS and a disseminated cryptococcal infection., Conclusion: Over a 20-month course, the patient was treated with fluconazole and antiretroviral therapy with very limited medication compliance. The disseminated infection caused cutaneous, hepatic, and cerebral complications. Eventually, compliance improved, and a final procedure to obtain post-treatment cultures and apply antifungal bone matrix was completed. The patient cleared the infection and will likely require lifetime antifungal treatment., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C424)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Objective: This study aims to quantitatively assess the relationship between the patella alignment and morphology and knee osteoarthritis (KOA), as well as the kinematics and kinetics of the knee, using gait analysis., Methods: Eighty age-matched patients with KOA and control subjects were evaluated. Incident radiographic osteoarthritis (iROA) was identified using a Kellgren-Lawrence (KL) grade of ≥ 2. The modified Insall-Salvati ratio (Mod-ISR), patellar tilt angle (PTA), and patella index (PI) were utilized to evaluate the sagittal and transverse alignment of the patella and its morphology, respectively. Regression analyses were conducted to explore associations between patellar measurements and KOA, iROA, kinematics, and kinetics., Results: Significant differences were observed between the control and KOA groups in terms of KL grade, patella alta, abduction angle, and reaction force to the ground (P < 0.05, respectively). Following adjustment for covariates, a significant positive association was found between patella alta and KOA (OR = 0.307, 95%CI: 0.103 to 0.918, P = 0.035). Additionally, a significant negative association was observed between PTA and abduction angle (B = -0.376, 95%CI: -0.751 to -0.002; P = 0.049). The PI exhibited a statistically significant association with log-transformed vertical ground reaction force (B = 0.002, 95%CI: 0.001 to 0.003, P = 0.002). Furthermore, adjustment for covariates did not reveal any significant correlations with other indicators (P > 0.05, respectively)., Conclusion: This study provides further evidence that proper alignment and morphology of the patella might be associated with maintaining normal biomechanical function. In addition, intervention measures targeting relevant patellar parameters, such as Mod-ISR, PTA, and PI, may positively impact KOA treatment outcomes., (© 2024. The Author(s).)

The objective of this descriptive cross-sectional study was to assess the functional outcomes of adolescents who had undergone internal fixation for patellar post-traumatic OCD fracture from 2019-2021. The injury mechanism was divided into two categories: a) torsional mechanism and b) direct contact injury. All candidates underwent X-ray and MRI/CT scan prior to the surgery to confirm the diagnosis. Operative treatment was open reduction and internal fixation (ORIF) of osteochondral fragment using headless screws. All patients were assessed pre-operatively with knee-ROM/IKDC (International Knee Documentation committee) score and satisfaction score, and postoperatively at one year follow-up. Fourteen patients were selected, with the mean age of 16.1±3.2 years. On one-year follow-up, no difference was noted in ROM when compared to the unaffected limb. The mean satisfaction score was 86±6.3 %. The mean pre-operative-IKDC score was 47.6±5.8 out of 100, whereas on one-year follow-up it was 88.6±2.2 which was statistically significant (p<0.05). Excellent outcomes can be achieved with headless screws for urgent ORIF (next elective list) of the osteochondral fragment.

Rationale and Objectives: The purpose of this study is to delineate cross-sectional associations between qualitative and quantitative measures of the infrapatellar fat pad (IPFP) and knee symptoms, structure, kinematics, and kinetics in older adults., Methods: Ninety eligible subjects (90 knees, mean age 54.0 years, 68.9% female) were examined at our center. We used T2-weighted fat-suppressed magnetic resonance imaging (MRI) to evaluate signal intensity alteration, maximum sagittal area, and depth of the IPFP. Symptomatic osteoarthritis (SOA) was a pain subscale score greater than 0 on the Western Ontario McMaster Osteoarthritis Index. A Kellgren-Lawrence grade ≥ 2 identified incident radiographic osteoarthritis (iROA). Three-dimensional gait data were employed to analyze knee joint kinematics and kinetics. Correlation and regression analyzes assessed associations between IPFP measurements and SOA, iROA, kinematics, and kinetics., Results: There were strong and positive associations between IPFP signal intensity alteration and both SOA and iROA in multivariable regression analyzes [OR (95% CI): 2.849 (1.440 to 5.636), 2.356 (1.236 to 4.492), respectively]. Conversely, a significant negative correlation was observed between IPFP maximum area and flexion angle [B (95%CI): - 1.557 (-2.549 to -0.564)]. Moreover, adjusting for covariates did not reveal any significant correlation between IPFP parameters and other indicators (P > 0.05, respectively)., Conclusion: IPFP signal intensity alteration and area were associated with knee clinical symptoms, structural abnormalities, and flexion angle in adults over 40, respectively. These findings suggest that IPFP may be a crucial imaging biomarker in early and middle knee osteoarthritis., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Hongsheng Zhan reports financial support was provided by Shanghai Municipal Health Commission. Hongsheng Zhan reports financial support was provided by National Natural Science Foundation of China. Guoqing Du reports financial support was provided by National Natural Science Foundation of China. Zhengming Wang reports financial support was provided by Shanghai University of Traditional Chinese Medicine. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.)

Background: A consequence of a high riding patella is reduced osseous stability and malalignment of the patella (i.e., lateral patellar tilt and displacement). Although quantification of patellar height is a routine part of the radiographic examination of the patellofemoral joint, it is not clear which measure of patellar height is best associated with patella alignment., Hypothesis/purpose: To determine if patellar articular overlap (PAO) is better associated with lateral patellar tilt and lateral patellar displacement compared to traditional measures of patellar height., Study Design: Cross-sectional., Methods: Magnetic resonance images were obtained from 50 female participants (21 with patellofemoral pain and 29 healthy controls) under loaded conditions (25-35% bodyweight) at 15-20 degrees of knee flexion. Measurements of lateral patellar tilt and displacement as well as the PAO, Insall-Salvati ratio (ISV), Caton Deschamps-index (CD-index), or the Blacburn Peel-index (BP-index) were obtained from sagittal and axial plane images., Results: The PAO was found to significantly correlated with lateral patellar tilt (r = -0.77, p < 0.001). In contrast, the ISV, CD-index, or the BP-index were not found to be associated with lateral patellar tilt (r = 0.13, p = 0.34; r = -0.14, p = 0.33; r = -0.08, p = 0.56, respectively). Both the PAO and ISV were found to be significantly correlated with lateral patellar displacement (r = -0.52, p < 0.001; r = 0.43, p = 0.002, respectively). Conversely, the CD-index and BP-index were not found to be associated with lateral patellar displacement (r = 0.03 p = 0.83; r = 0.05 p = 0.74, respectively)., Conclusion: Of the measures of patellar height evaluated, the PAO was found to provide the greatest association with lateral patellar tilt and displacement., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: Abnormal patellar height has been identified as a source of aberrant mechanical functioning within the patellofemoral joint. The purpose of this study is to examine the statistical agreement among three commonly used classification methods: Blackburne-Peel (BPI), Caton-Deschamps (CDI) and Insall-Salvati (ISR), by evaluating (1) the rates of patella alta identification and (2) the ability for one index to predict another., Methods: One hundred lateral knee radiographs were evaluated using BPI, CDI and ISR to classify each knee as patella normal, patella alta or patella baja. Linear regression analysis was performed to evaluate the relationship between each index. Conversion equations were then derived using the reported linear regression best-fit line, comparing each pair of indices., Results: Patella alta was identified in 15 knees using BPI, 15 using CDI and 25 using ISR. A total of seven knees were classified as patella alta by all BPI, CDI and ISR. Statistical analysis revealed significant correlation (p ≤ 0.001) among BPI and CDI (R 2  = 0.706), BPI and ISR (R 2  = 0.328) and CDI and ISR (R 2  = 0.288). Wilcoxon Signed-Rank test between the three indices revealed no significant difference between the means of converted and original indices., Conclusion: Despite their significant correlations and adequate reproducibility, variability between common patellar height indices render predictions and conversions between BPI, CDI and ISR inequivalent. Users of these indices must be aware of their incongruent properties when considering application to patients in the clinical setting. Furthermore, it remains unclear which patellar height measurement technique is the correct index to use in a given knee. This study highlights the need for further investigation to create a reliable and standardised method for identifying patella height., Level of Evidence: Level IV., (© 2024 The Authors. Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Background: Anatomic patellar components for total knee arthroplasty (TKA) have demonstrated favorable in vivo kinematics. A novel failure mechanism in TKA patients with an anatomic patellar component was observed prompting an investigation to identify patient- and implant-related factors associated with suboptimal performance., Methods: A retrospective evaluation was performed comparing 100 TKA patients with an anatomic patellar component to 100 gender-, age-, and body mass index-matched patients with a medialized dome component. All surgeries were performed with the same posterior-stabilized TKA system with minimum of 1-year follow-up. Several radiographic parameters were assessed. A separate computational evaluation was performed using finite-element analysis, comparing bone strain energy density through the patella bone remnant., Results: Patients with an anatomic patellar component had significantly higher rates of anterior knee pain (18 versus 2%, P < .001), chronic effusions (18 versus 2%, P < .001), and superior patellar pole fragmentation (36 versus 13%, P < .001) compared to those with a dome component. Radiographically, the anatomic group demonstrated more lateral patellar subluxation (2.3 versus 1.1 mm, P < .001) and lateral tilt (5.4 versus 4.0 mm, P = .013). Furthermore, there were more revisions in the anatomic group (7 versus 3, P = .331). On computational evaluation, all simulations demonstrated increased bone strain energy density at the superior patellar pole with the anatomic patella. Resection thickness <13 mm resulted in over 2-fold higher strain energy density, and negative resection angle of 7° resulted in 6-fold higher superior pole strain energy., Conclusions: Patients with an anatomic patellar component showed higher rates of anterior knee pain, chronic effusion, and superior pole fragmentation compared to patients with a dome patella, with higher superior patellar pole strain energy confirmed on computational evaluation. Avoiding higher resection angles and excessive patellar resection may improve the performance and survivorship of the anatomic patella., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Patellar dislocations in flexion, which occurs permanently with every movement, is the most serious manifestation of patellofemoral malalignment. Surgical approaches to correct this problem have been mostly unsuccessful. In a new therapeutic approach, the concave posterior surface of the patella, which slides on the hypoplastic lateral condyle as if guided by splints, is seen as the main pathology. The appropriate surgical strategy is trochleoplasty, combined with closed wedge patellar osteotomy, tuberosity medialisation, procedure for lengthening lateral retinaculum and MPFL plasty with the quadriceps tendon. In the case of a 13-year-old female patient presented here, this procedure leads to permanent stability in a symptom-free knee joint on both sides., Competing Interests: Die Autorinnen/Autoren geben an, dass kein Interessenkonflikt besteht., (Thieme. All rights reserved.)

Background: Matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging outcomes in the treatment of knee cartilage defects, although limited research is available on its longer term (≥10 years) sustainability in the patellofemoral joint., Purpose: To report the clinical and radiological outcomes at ≥10 years in a prospectively recruited cohort of patients undergoing MACI in the patellofemoral joint and compare outcomes in patients undergoing MACI on the patella versus the trochlea., Study Design: Case series; Level of evidence, 4., Methods: The current study prospectively enrolled 95 patients who underwent patellofemoral MACI, of whom 29 (13 patella, 16 trochlea) underwent concomitant tibial tubercle osteotomy. Patients were assessed preoperatively and at 2, 5, and ≥10 years using a range of patient-reported outcome measures (PROMs) including the Knee injury and Osteoarthritis Outcome Score, the 36-item Short Form Health Survey, and the frequency and severity of knee pain as well as patient satisfaction, full active knee flexion and extension, and peak isokinetic knee extensor and flexor torques. High-resolution magnetic resonance imaging (MRI) was performed to assess pertinent graft parameters, as well as determine an overall MRI composite score, per the Magnetic Resonance Observation of Cartilage Repair Tissue scoring system. Results were analyzed according to the graft location (patella or trochlea)., Results: Of the 95 patients recruited, 82 patients (41 patella, 41 trochlea) were available for a clinical review at ≥10 years after surgery (mean follow-up, 11.9 years [range, 10-15 years]). For the whole patellofemoral MACI cohort, all PROMs significantly improved over time ( P < .05), with no significant changes ( P > .05) observed in any MRI-based score from 2 to ≥10 years after surgery. At ≥10 years, 90.2% (n = 74) were satisfied with MACI in relieving their knee pain, and 85.4% (n = 70) were satisfied with the improvement in their ability to participate in sports. No differences ( P > .05) were observed in PROMs between those undergoing patellar MACI and those undergoing trochlear MACI, although a significant group effect was observed for limb symmetry indices of knee extensor ( P = .009) and flexor ( P = .041) strength, which were greater in those undergoing patellar (vs trochlear) MACI. No statistically significant differences ( P > .05) were observed between patellar and trochlear grafts on any MRI-based measure. In the cohort assessed at ≥10 years after surgery, 4 patients (2 patella, 2 trochlea) demonstrated graft failure on MRI scans, although a further 3 patients (all trochlea) were omitted from the ≥10-year review for having already progressed to total knee arthroplasty., Conclusion: Good clinical scores, high levels of patient satisfaction, and adequate graft survivorship were observed at ≥10 years after MACI on the patella and trochlea., Competing Interests: Presented as a poster at the annual meeting of the AOSSM, Denver, Colorado, July 2024.One or more of the authors has declared the following potential conflict of interest or source of funding: This research has received funding from the National Health and Medical Research Council (ID254622 and ID1003452) and an independent research grant from Vericel that assisted with later-stage follow-up of patients. G.C.J. owns shares in Orthocell. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Objective: To analyze the influencing factors for patellofemoral joint (PFJ) overstuffing following total knee arthroplasty (TKA) without patella resurfacing, and explore the effect of PFJ overstuffing on clinical efficacy., Methods: A retrospective analysis was conducted on 168 patients with end-stage knee osteoarthritis who underwent TKA without patella resurfacing at our hospital between Match 2019 and September 2021. The clinical data of these patients were retrospectively analyzed. In this study, PFJ overstuffing was defined as a postoperative PFJ distance greater than 1 mm compared to the preoperative measurement. The occurrence of postoperative PFJ overstuffing was counted. The patients were divided into the overstuffing group (n = 109) and the non-overstuffing group (n = 59) to count the patellar thickness and thickness of femoral anterior condyle in all patients before and after surgery, and analyze the influencing factors for postoperative PFJ overstuffing in such patients. Patients were followed up for 2 years to compare the recovery time of postoperative pain, score of visual analogue scale (VAS) and flexion activity between the two groups., Results: There was no significant difference in patellar thickness between preoperative and postoperative measurements of the patients (P > 0.05). However, the thickness of the femoral anterior condyle and the PFJ distance after surgery increased significantly compared with those before surgery (P < 0.05). Among the 168 patients, 109 cases (64.88%) experienced PFJ overstuffing. The risk of PFJ overstuffing was higher in female patients than in male (P < 0.05). The preoperative thickness of the femoral anterior condyle in the overstuffing group was significantly smaller compared to the non-overstuffing group (P < 0.001). Compared with the non-overstuffing group, the overstuffing group had longer recovery time of postoperative pain (P < 0.05), and had lower flexion activity at 2 years after surgery (P < 0.001). However, no significant difference was found in VAS score between the overstuffing group and the non-overstuffing group at 2 years after surgery (P > 0.05). Spearman rank correlation analysis indicated females tend to have a lower preoperative thickness of the femoral anterior condyle (r=-0.424, P < 0.001), as well as a positive postoperative PFJ overstuffing (r = 0.237, P < 0.05). Furthermore, there was a negative correlation between preoperative thickness of the femoral anterior condyle and postoperative PFJ overstuffing (r=-0.540, P < 0.001)., Conclusion: Following TKA without patella resurfacing, there is a high risk of PFJ overstuffing, particularly among female patients and those with a small thickness of the femoral anterior condyle. Therefore, special attention should be given to these high-risk groups during clinical treatment., (© 2024. The Author(s).)

Background: Synovial hemangiomas are rare benign vascular anomalies surrounded by a synovial lining and were first described by Bouchut in 1856. These neoplasms can develop in the intra-articular region, resulting in effusions and knee pain. However, their cause remains unknown. Prompt diagnosis and intervention are critical to prevent chondral damage. Histopathological examination is used to achieve the diagnosis, which is often delayed because of a lack of specific clinical signs. This report describes a unique case in which a painful infrapatellar mass was diagnosed as a synovial hemangioma. The absence of typical magnetic resonance imaging (MRI) findings highlights the importance of arthroscopic excision for diagnosis and symptom relief., Case Presentation: A 20-year-old woman presented with persistent anterior left knee pain that became exacerbated when she climbed stairs. Despite previous pain management and physical therapy, she developed a painful lump beneath her patella that worsened over time. She had also undergone arthrocentesis, but this did not relieve her pain. Physical examination revealed a palpable, immobile 5-cm mass along the patellar tendon with limited knee flexion and extension and normal ligament stability. T1-weighted fat-saturated MRI of the left knee with gadolinium-based contrast revealed a lobulated intra-articular mass in Hoffa's fat pad that resembled a soft tissue chondroma. A biopsy of the mass was performed to provide histopathological evidence, confirming the benign nature of the mass. The subsequent excisional arthroscopy, combined with incision enlargement for mass removal, confirmed the histopathologic diagnosis of synovial hemangioma based on the presence of numerous dilated blood vessels and venous proliferation within sections of the synovium. Recovery was complete, and no residual tumor was detected on follow-up MRI after 1 year., Conclusion: This case study emphasizes the importance of arthroscopic excision over open surgery for patients with synovial hemangioma. The minimally invasive nature of arthroscopy combined with the well-encapsulated nature and location of the mass facilitates complete resection., (© 2024. The Author(s).)

Patellofemoral instability (PFI) is a common condition in children and adolescents, ranging from mild discomfort and mal-tracking to lateral patellar dislocation [1]. A number of anatomical risk factors have been described in the literature, such as trochlear dysplasia, patella alta, excessive tibial tuberosity to trochlear groove (TT-TG) distance, patellar tilt and soft tissue alterations [2]. Among them, TD has been identified as the main anatomical risk factor with the strongest association with PFI [1, 2]. In the study by Dejour et al. [2] radiographically observed TD was identified in 96% of patients with a history of patellofemoral dislocation [1, 2]. Patients with Dejour Type D dysplasia are characterized by a prominent and convex lateral facet with a vertical connection to a hypoplastic medial facet (Figure 1), which provides inadequate tracking of the patella in the trochlea during flexion leading to patella subluxation [2]. Non-operative treatment of lateral patellar dislocation presents a rate of re-dislocation up to 70% within 24 months of the first episode [3]. Sulcus deepening trochleoplasty is indicated for Type B and D dysplasia, in order to improve patella tracking, reduce the rate of re-dislocation and achieve good functional outcomes [2, 4]. Trochlea dysplasia is defined as a shallow or flattened groove with decreased resistance to lateral patellar translation. TD can be assessed on computed tomography (CT) and magnetic resonance imaging (MRI) with the use of overlapping axial images and are able to show perfectly the global shape of the femoral trochlea [2]. The thresholds for identifying trochlear dysplasia are established based on the sulcus angle ≥ 145°, medial/lateral trochlea facet asymmetry < 40%, trochlear depth < 3 mm and lateral trochlear inclination ≤ 11° and therefore it can be used in young adolescents [4, 5]. A deep knowledge of anatomic variations and abnormalities of the patellofemoral joint, which may predispose to PFI, is crucial in order to choose the appropriate treatment for each patient., (© 2024 Angelo V. Vasiliadis et al., published by Sciendo.)

Background: Because of the increased prevalence of revision anterior cruciate ligament (ACL) reconstruction, there has been a desire to understand the role of posterior tibial slope on increased anterior tibial translation and increased ACL graft forces. One potential concern in supratubercle anterior closing wedge proximal tibial osteotomy (ACW-PTO) for decreasing the posterior tibial slope is the risk of altering the patellar height., Purpose: To radiographically assess changes in (1) patellar height, (2) anterior tibial translation, and (3) posterior tibial slope after supratubercle ACW-PTO., Study Design: Case series; Level of evidence, 4., Methods: Patients who underwent supratubercle ACW-PTO by a single surgeon between July 2019 and June 2023 were included. Standardized lateral knee weightbearing radiographs to assess patellar height (via the Caton-Deschamps index), anterior tibial translation of the lateral tibial plateau relative to the lateral femoral condyle, and posterior tibial slope were obtained at 4 time points (preoperatively and 1 day, 3 months, and 6 months postoperatively). Paired t test was used to compare differences between preoperative, 1-day, and 3- and 6-month values for patellar height as measured using the Caton-Deschamps index and for posterior tibial slope. Paired t test was also used to compare differences in the preoperative and 6-month postoperative values for anterior tibial translation., Results: In 20 patients after ACW-PTO, the Caton-Deschamps index demonstrated a significant increase in patellar height on postoperative day 1 ( P < .001) but no significant differences at 3 ( P = .057) and 6 ( P = .176) months postoperatively. Anterior tibial translation on standing lateral knee radiographs was significantly decreased by a mean of 8.9 mm from preoperatively to 6 months postoperatively ( P < .001). Posterior tibial slope was significantly decreased by a mean of 11.2° from preoperatively to 6 months postoperatively ( P < .001)., Conclusion: Supratubercle ACW-PTO performed for ACL reconstruction failure in the setting of an increased posterior tibial slope did not induce significant changes in patellar height postoperatively. Furthermore, after ACW-PTO, there was a significant decrease in anterior tibial translation and posterior tibial slope., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: N.I.K. has received support for education from Foundation Medicine and Smith & Nephew and hospitality payments from Zimmer Biomet and Encore Medical. C.A.W. has ownership and investment interest in Responsive Arthroscopy and has received speaking fees from Smith & Nephew. C.M.L. has received speaking fees from Smith & Nephew and Synthes and consulting fees from Smith & Nephew and Responsive Arthroscopy. R.F.L. has received consulting fees from Ossur, Smith & Nephew, and Responsive Arthroscopy; royalties from Ossur, Smith & Nephew, Elsevier, and Arthrex; research support from Ossur and Smith & Nephew; and support for education from Foundation Medicine. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Purpose: To explore the relationship between preoperative J-sign grading and structural bone abnormalities in patients with recurrent patellar dislocation (RPD)., Methods: A retrospective study was conducted on RPD patients over 5 years. Patients were categorised based on J-sign grade into low (J- and J1+), moderate (J2+) and high groups (J3+). Trochlear dysplasia (TD) and osseous structures (femoral anteversion angle [FAA], knee torsion, tibial tuberosity-trochlear groove [TT-TG] distance, Caton-Deschamps index) were assessed and grouped according to risk factor thresholds. The χ 2 test was used to compare composition ratio differences of structural bone abnormalities among the groups., Results: A total of 256 patients were included, with 206 (80.5%) females. The distribution of J-sign grade was as follows: 89 knees (34.8%) of low grade, 86 moderate (33.6%) and 81 high (31.6%). Among the five structural bone abnormalities, TD was the most common with a prevalence of 78.5%, followed by increased TT-TG at 47.4%. Excessive tibiofemoral rotation had the lowest occurrence at 28.9%. There were 173 (67.6%) patients who had two or more abnormalities, while 45 (17.6%) had four to five bony abnormalities. Among patients with any bony abnormality, the proportion of high-grade J-sign surpassed 40%. Patients with moderate and high-grade J-sign had more increased FAA and more pronounced patella alta (all p < 0.001). The proportion of excessive knee torsion and TD increased with increasing each J-sign grade, with the more notable tendency in knee torsion (high vs. moderate vs. low-grade: 61% vs. 22% vs 7%, p < 0.001). Furthermore, the higher J-sign grade was also associated with more combined bony abnormalities (p < 0.001). In the high-grade J-sign group, 90.2% of the knees had two or more bony risk factors and 40.7% had four or more, which were significantly higher than the moderate and low-grade J-sign groups (40.7% vs. 11.6% vs. 2.2%, p < 0.001)., Conclusion: In patients with a high-grade J-sign, over 90% of the lower limbs had two or more structural bone risk factors, and more than 40% had four or more. These proportions were significantly higher compared to knees with low-grade and moderate J-sign. In clinical practice, when treating high-grade patellar mal-tracking, it is important to focus on and correct these strongly correlated abnormal bone structures., Level of Evidence: Level III., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Introduction: The radiographical assessment of patella height has historically been performed using X-Ray. The aim of this study was to evaluate a new method for the assessment of patella height using MRI and to assess the correlation with the X-Ray based assessment., Materials and Methods: 159 patients who had both lateral radiographs and MRI images were included. Parameters measured included traditional radiographical CDI, MRI-based CDI, and TT-TG distance. On the basis of the TT-TG, the patients were divided into 2 groups. Two different methods were used to assess CDI using MRI: using a single slice image, and an alternative technique using two different cross-sectional images. The correlation of the two measurement methods was assessed using Pearson's correlation coefficient. The intraclass correlation coefficient (ICC) was determined from the measurements of the two investigators., Results: The average TT-TG distance was 11.6 mm (± 4.6). In patients with a TT-TG < 15 mm, both measurement methods showed comparable correlation with measurements on X-Ray. In patients with a TT-TG of > 15 the the new cross-sectional imaging method showed higher correlation with traditional X-Ray assessment compared to CDI assessment using the traditional single slice method (r = 0.594, p < 0.001 vs. r = 0.302, p = 0.055)., Conclusions: The assessment of CDI on MRI using a cross-sectional imaging method has a better correlation with traditional X-Ray assessment of CDI than single-slice assessment. This is particularly true in patients with elevated TT-TG and as such should be preferentially used in the assessment of Patellar height in this cohort., (© 2024. The Author(s).)

Objective: To qualitatively and quantitatively evaluate the 2.5-year MRI outcome after Matrix-associated autologous chondrocyte implantation (MACI) at the patella, reconstruction of the medial patellofemoral ligament (MPFL), and combined procedures., Methods: In 66 consecutive patients (age 22.8 ± 6.4years) with MACI at the patella (n = 16), MPFL reconstruction (MPFL; n = 31), or combined procedures (n = 19) 3T MRI was performed 2.5 years after surgery. For morphological MRI evaluation WORMS and MOCART scores were obtained. In addition quantitative cartilage T2 and T1rho relaxation times were acquired. Several clinical scores were obtained. Statistical analyses included descriptive statistics, Mann-Whitney-U-tests and Pearson correlations., Results: WORMS scores at follow-up (FU) were significantly worse after combined procedures (8.7 ± 4.9) than after isolated MACI (4.3 ± 3.6, P = 0.005) and after isolated MPFL reconstruction (5.3 ± 5.7, P = 0.004). Bone marrow edema at the patella in the combined group was the only (non-significantly) worsening WORMS parameter from pre- to postoperatively. MOCART scores were significantly worse in the combined group than in the isolated MACI group (57 ± 3 vs 88 ± 9, P < 0.001). Perfect defect filling was achieved in 26% and 69% of cases in the combined and MACI group, respectively (P = 0.031). Global and patellar T2 values were higher in the combined group (Global T2: 34.0 ± 2.8ms) and MACI group (35.5 ± 3.1ms) as compared to the MPFL group (31.1 ± 3.2ms, P < 0.05). T2 values correlated significantly with clinical scores (P < 0.005). Clinical Cincinnati scores were significantly worse in the combined group (P < 0.05)., Conclusion: After combined surgery with patellar MACI and MPFL reconstruction inferior MRI outcomes were observed than after isolated procedures. Therefore, patients with need for combined surgery may be at particular risk for osteoarthritis., (© 2024. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Background: The polyarticular nature of Osteoarthritis (OA) tends to manifest in multi-joints. Associations between cartilage health in connected joints can help identify early degeneration and offer the potential for biomechanical intervention. Such associations between hip and knee cartilages remain understudied., Purpose: To investigate T 1p associations between hip-femoral and acetabular-cartilage subregions with Intra-limb and Inter-limb patellar cartilage; whole and deep-medial (DM), deep-lateral (DL), superficial-medial (SM), superficial-lateral (SL) subregions., Study Type: Prospective., Subjects: Twenty-eight subjects (age 55.1 ± 12.8 years, 15 females) with none-to-moderate hip-OA while no radiographic knee-OA., Field Strength/sequence: 3-T, bilateral hip, and knee: 3D-proton-density-fat-saturated (PDFS) Cube and Magnetization-Prepared-Angle-Modulated-Partitioned-k-Space-Spoiled-Gradient-Echo-Snapshots (MAPSS)., Assessment: Ages of subjects were categorized into Group-1 (≤40), Group-2 (41-50), Group-3 (51-60), Group-4 (61-70), Group-5 (71-80), and Group-6 (≥81). Hip T 1p maps, co-registered to Cube, underwent an atlas-based algorithm to quantify femoral and acetabular subregional (R 2 -R 7 ) cartilage T 1p . For knee Cube, a combination of V-Net architectures was used to segment the patellar cartilage and subregions (DM, DL, SM, SL). T 1p values were computed from co-registered MAPSS., Statistical Tests: For Intra-and-Inter-limb, 5 optimum predictors out of 13 (Hip subregional T 1p , age group, gender) were selected by univariate linear-regression, to predict outcome (patellar T 1p ). The top five predictors were stepwise added to six linear mixed-effect (LME) models. In all LME models, we assume the data come from the same subject sharing the same random effect. The best-performing models (LME-model best ) selected via ANOVA, were tested with DM, SM, SL, and DL subregional-mean T 1p . LME assumptions were verified (normality of residuals, random-effects, and posterior-predictive-checks)., Results: LME-model best (Intra-limb) had significant negative and positive fixed-effects of femoral-R 5 and acetabular-R 2 T 1p , respectively (conditional-R 2  = 0.581). LME-model best (Inter-limb) had significant positive fixed-effects of femoral-R 3 T 1p (conditional-R 2  = 0.26)., Data Conclusion: Significant positive and negative T 1p associations were identified between load-bearing hip cartilage-subregions vs. ipsilateral and contralateral patellar cartilages respectively. The effects were localized on medial subregions of Inter-limb, in particular., Evidence Level: 1 TECHNICAL EFFICACY: Stage 1., (© 2023 The Authors. Journal of Magnetic Resonance Imaging published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.)

Background: The infrapatellar fat pad (IPFP) lies extrasynovial and intracapsular, preserving the joint cavity and serving as a biochemical regulator of inflammatory reactions. However, there is a lack of research on the relationship between anterior knee pain (AKP) and the IPFP after medial patellofemoral ligament reconstruction (MPFLR). Pinpointing the source of pain enables clinicians to promptly manage and intervene, facilitating personalized rehabilitation and improving patient prognosis., Methods: A total of 181 patients were included in the study. These patients were divided into the AKP group (n = 37) and the control group (n = 144). Clinical outcomes included three pain-related scores, Tegner activity score, patient satisfaction, etc. Imaging outcomes included the IPFP thickness, IPFP fibrosis, and the IPFP thickness change and preservation ratio. Multivariate analysis was used to determine the independent factors associated with AKP. Finally, the correlation between independent factors and three pain-related scores was analyzed to verify the results., Results: The control group had better postoperative pain-related scores and Tegner activity score than the AKP group (P < 0.01). The AKP group had lower IPFP thickness change ratio and preservation ratio (P < 0.001), and smaller IPFP thickness (P < 0.05). The multivariate analysis revealed that the IPFP thickness change ratio [OR = 0.895, P < 0.001] and the IPFP preservation ratio [OR = 0.389, P < 0.001] were independent factors related to AKP, with a significant correlation between these factors and pain-related scores [|r| > 0.50, P < 0.01]., Conclusions: This study showed the lower IPFP change ratio and preservation ratio may be independent factors associated with AKP after MPFLR. Early detection and targeted intervention of the underlying pain sources can pave the way for tailored rehabilitation programs and improved surgical outcomes. LEVEL OF EVIDENCE LEVEL III., (© 2024. The Author(s).)

Patellofemoral instability results from impaired engagement of the patella in the trochlear groove at the start of flexion and may lead to pain and lateral patellar dislocation. It occurs most frequently in adolescents and young adults during sporting activities. Trochlear dysplasia, patella alta, and excessive lateralization of the tibial tuberosity are the most common risk factors for patellar instability. The main role of imaging is to depict and assess these anatomical factors and highlight features indicating previous lateral dislocation of the patella., Competing Interests: None declared., (Thieme. All rights reserved.)

Introduction: There is growing interest in the use of robotic TKA to improve accuracy of component positioning in Total Knee Arthroplasty (TKA). The aim of this study was to investigate the accuracy of implant component position using the ROSA® knee system with specific reference to Joint Line Height, Patella Height and Posterior Condylar Offset (PCO)., Methods: This was a retrospective review of a prospectively-maintained database of the initial 100 consecutive TKAs performed by a high volume surgeon using the ROSA® knee system. Both the image-based and imageless workflow were used and two prosthesis types were implanted. To determine the accuracy of component positioning, the immediate post-operative radiograph was reviewed and compared with the immediate pre-operative radiograph with regards to Joint Line Height, Patella Height and Posterior Condylar Offset., Results: 100 consecutive patients undergoing TKA using the ROSA system were included; mean age 70 years (range 49-95 years). Mean change in joint line height was 0.2 mm, patella height (Insall-Salvati ratio) 0.01 and posterior condylar offset 0.02 mm; there was no statistically significant difference between the pre and post-operative values. No difference was demonstrated between image-based or imageless workflows, or between implant design (Persona versus Vanguard) regarding joint line height, patella height and PCO., Conclusion: This study validates the use of the ROSA® knee system in accurately restoring Joint Line Height, Patella Height and Posterior Condylar Offset in TKA surgery. No significant differences were found between imageless and image-based groups, or between implant designs (Persona versus Vanguard)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Objectives: Patellofemoral instability (PFI) has multiple predisposing anatomic factors, including ligamentous hyperlaxity, coronal and axial malalignment, patella alta, trochlea dysplasia, excessive lateral patellar tilt, and excessive lateral Q vector. Yet, few studies have analyzed surgical thresholds for performing axial alignment corrective osteotomies in the treatment of PFI and patella maltracking. The objective of this systematic literature review was to determine if there is a threshold for axial plane alignment that triggers surgical correction for the treatment of patellar instability in the published literature., Methods: Using a predetermined search strategy, a systematic literature search of 10 major databases and gray literature resources was completed. Only studies reporting on patellar instability and outcomes were included. Radiologic indications, additional procedures, outcomes, and complications were reported. Titles and abstracts were screened, and full-text manuscripts were then selected and extracted. Variables related to radiographic and clinical parameters, patient demographics, surgery performed, surgical correction, complications, and reoperations were recorded preoperatively and postoperatively., Results: A total of 1132 abstracts and titles were screened by two reviewers, yielding 15 eligible studies. The reported threshold identified in our study for axial plane alignment that triggers surgical correction in most of the published literature when discussing PFI was either tibial torsion greater than 30° and/or femoral anteversion greater than 25°. Following rotational osteotomy of one or both long bones, one study (7%) reported improvements in tubercle-sulcus angle, two studies (13%) reported improvements in femoral-tibial angle, and four studies (27%) reported decreases in tibial torsion. For patient-reported outcomes, seven studies (47%) reported improvement in the Kujala score, five studies (33%) reported postoperative improvement in Lysholm, and four studies (27%) reported improvement in the International Knee Documentation Committee (IKDC) score. Nine studies (60%) reported preoperative femoral anteversion; however, only two studies compared pre- and post-operative values (one study reported a decrease in anteversion and another study reported an increase in anteversion)., Conclusion: When treating PFI, the reported threshold for axial plane alignment that triggers surgical correction in most of the published literature was tibial torsion greater than 30° and/or femoral anteversion greater than 25° as measured by CT. However, there is no consensus on the axial alignment measurement technique., Level of Evidence: III., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: There are several imaging-based measurements for patellofemoral height, which are obtained from sagittal images. However, these methods can be misleading with sagittal oblique slices and when the patella is tilted and/or chronically subluxated. This study aimed to describe a simple method of measuring patellar height using axial patellotrochlear overlap (APTO) on MRI., Methods: A retrospective observational study of 97 knees from 251 patients, excluding those with fractures, massive effusion, or patellofemoral conditions. APTO was measured as follows: (1) patellar length (P) - expressed as the number of axial images showing patellar articular cartilage; (2) trochlear overlap (T) - the number of axial images showing the overlap between patellar articular cartilage and articular cartilage of the lateral trochlea. APTO is the ratio T/P. All measurements were performed independently by six raters on two separate occasions. The raters were two orthopaedic consultants, one knee surgery fellow, two consultant musculoskeletal radiologists, and one radiology fellow. The conventional patellotrochlear index (PTI) was measured as a control for all patients by a senior musculoskeletal radiologist., Results: The mean APTO value was 36.7% (range 14.2-66.6; standard deviation 11.4). There was a positive correlation with the PTI, Pearson correlation coefficient: 0.76, P < 0.001. Intra-observer reliability was good (intraclass correlation coefficient(ICC): 0.66, 95% confidence interval (CI) 0.54, 0.76, P < 0.001). Inter-observer reliability was fair (ICC: 0.51, 95% CI 0.41, 0.6, P < 0.001)., Conclusions: APTO was shown to be a reliable measurement of patellar height and correlated with existing PTI for patellar height. Measurement of APTO on MRI could be a reliable alternative for the evaluation of patellar height. However, further studies are required to assess its validity in patients with patellofemoral pathology., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2024. Published by Elsevier B.V. All rights reserved.)