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Background: The Banff Patellofemoral Instability Instrument 2.0 (BPII 2.0) is a disease-specific, quality of life patient-reported outcome measure (PROM) that is valid and reliable in patients with recurrent lateral patellofemoral instability (LPI). Quality of life encompasses the physical, emotional, and psychological aspects of patient functioning and recovery. Purposes: To concurrently validate the BPII 2.0 to the Tampa Scale for Kinesiophobia (TSK-11), the Pain Catastrophizing Scale (PCS), and the Anterior Cruciate Ligament–Return to Sport after Injury Scale (ACL-RSI) in patients presenting with recurrent LPI and to assess baseline values for the PROMs in patients with LPI. Study Design: Cohort study (Diagnosis); Level of evidence, 2. Methods: A total of 107 consecutive patients with recurrent LPI were assessed between January and October 2021. Patients completed the BPII 2.0, TSK-11, PCS, and ACL-RSI. A Pearson r correlation coefficient was employed to examine relationships between the PROMs. Baseline values, as well as floor and ceiling effects and Cronbach alpha, were assessed for all PROMs. Results: All 107 patients completed the 4 PROMs. Patients included 28 men (26.2%) and 79 women (73.8%), with a mean (SD) age of 25.7 (9.8) years. The mean (SD) age at first dislocation was 14.8 (6.3) years. The TSK-11, PCS, and ACL-RSI were all statistically significantly correlated with the BPII 2.0 (P <.01; 2-tailed), with moderate correlations (r = -0.361-0.628) The R 2 values indicated an overlap of the constructs measured by the PROMs. Conclusion: A statistically significant correlation was evident between the BPII 2.0 and the other PROMs. The BPII 2.0 does not explicitly measure kinesiophobia or pain catastrophizing; however, the significant statistical relationship of the TSK-11 and PCS to the BPII 2.0 suggests that this information is being captured and reflected. [ABSTRACT FROM AUTHOR]

Purpose: To assess the outcomes of medial patellofemoral ligament (MPFL) reconstruction using synthetic suture tape in paediatric patients with patellofemoral instability (PFI). Methods: This ambispective comparative study, conducted from 2014 to 2022, included paediatric patients who underwent MPFL reconstruction with synthetic suture tape and had a minimum follow‐up of 1 year. Pre‐ and postoperative clinical and functional outcomes, patient satisfaction and complications were assessed. Results: The study comprised 22 patients (29 knees), with a median age at surgery of 14.4 years (interquartile range [IQR] 10.9–16.7) and a median follow‐up of 46.5 months (24.7–66). Notably, 13 knees (44.8%) had open growth plates at the time of surgery. The cohort included patients with Down syndrome (3 patients), Ehlers‐Danlos (2), arthrogryposis (1), generalized joint hypermobility (8) and previous unsuccessful PFI surgeries (8). Concomitant procedures were performed on 16 knees. Postoperatively, improvements were observed in all but one patient, who reported residual pain. There were two other complications: one suture‐tape rupture and one surgical wound infection. Functional scores significantly improved: Kujala, +14 points (7–29) (p < 0.001); IKDC, +10.5 points (5.2–25.3) (p < 0.001); Tegner, +2 points (0–4) (p < 0.001); Lysholm, +15 points (0–37.5) (p < 0.001). Most patients achieved excellent outcomes by Crosby‐Insall criteria (21 patients, 72.4%) and reported high satisfaction (23 patients, 79.3%). Conclusions: MPFL reconstruction using synthetic suture tape is a viable and effective treatment for paediatric patients with PFI, particularly for those with connective tissue disorders, generalized joint hypermobility or past surgical failures, significantly enhancing clinical and functional outcomes with an acceptable complication rate. Level of Evidence: Level IV. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: The association between the prevalence of patellofemoral arthritis (PFA) and femoral tunnel positioning following isolated medial patellofemoral ligament reconstruction (MPFLr) has not been well described. The aim of this study was to analyse the relationship between femoral tunnel positioning and the prevalence of PFA. Methods: This was a single‐centre study of patients undergoing an isolated MPFLr between 2006 and 2011 with a minimum of 10 years of follow‐up. Outcomes assessed were the presence of PFA on radiographs, recurrence of instability requiring revision surgery and patient‐reported outcomes, including Kujala, Tegner and IKDC scores. Tunnel positioning was assessed on postoperative radiographs using two radiographic methods: Schöttle's point and the grid method to localise the femoral tunnel. Patients were grouped based on tunnel positioning and compared. Results: Fifty patients were analysed at a mean follow‐up of 12.4 years. Thirty‐three patients (66%) had a femoral tunnel position within 7 mm of Schöttle's point and 39 (78%) within the anatomic quadrant, with the most common location according to the grid method in D4 (28%) and E4 (26%), respectively. Thirty‐seven patients (74%) had a satisfactory (>80 versus <80) Kujala score at long‐term follow‐up. None of the examined tunnel assessment methods demonstrated a significant relationship with Tegner, Kujala or International Knee Documentation Committee scores. Patients with a femoral tunnel position >7 mm outside Schöttle's point or were considered to be in a nonanatomic position were not significantly more likely to result in unsatisfactory Kujala scores at the last follow‐up. Tunnel positioning and the other tested parameters were not found to be significantly associated with the development of PFA. Conclusion: No correlation between femoral tunnel position and risk of PFA or poor outcomes was observed in patients undergoing isolated MPFLr at long‐term follow‐up. The impact of femoral tunnel placement on long‐term outcomes in patients with PFI may be less significant than originally considered. Level of Evidence: Level IV. [ABSTRACT FROM AUTHOR]

Purpose: Tibial tubercle osteotomy (TTO) is often employed for certain patellofemoral instability (PFI) cases, though its indications and effectiveness are not widely accepted. This systematic review gathers recent studies comparing isolated medial patellofemoral ligament reconstruction (iMPFLR) to MPFLR combined with TTO in managing PFI and to offer recommendations for clinicians when selecting TTO. This review proposes that MPFLR combined with TTO is superior to iMPFLR and that the combined procedure does not increase the incidence of postoperative complications. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (PRISMA 2020), extensive searches were performed on August 20, 2024, across PubMed/Medline, Embase, and Cochrane databases to locate relevant studies. Data on research protocols, participant characteristics (including epidemiological and radiographic features), functional scores, and complications were collected and examined. A meta-analysis was conducted to compare the outcomes between the two surgical techniques. Results: This systematic review analyzed 10 studies involving 715 participants, divided into a control group (which underwent iMPFLR) and an experimental group (which underwent MPFLR combined with TTO). In the control group, the incidence of severe trochlear dysplasia before surgery was 68.3% (95% CI [67.3-69.3%]), and the mean preoperative tibial tubercle to trochlear groove distance (TT-TG) was 16.1 mm (95% CI [15.8–16.3]). In the experimental group, both were respectively 79.1% (95% CI [77.5–80.7]) and 20.2 mm (95% CI [20.0-20.4]). Eight studies (80%) reported postoperative Kujala scores, with an average score of 85.1 (95% CI [84.4–85.9]) for the control group and 85.4 (95% CI [84.9–85.9]) for the experimental group (I²=22.7%). Four studies (40%) reported postoperative Lysholm scores, with an average score of 89.4 (95% CI [88.9–89.9]) for the control group and 89.1 (95% CI [89.0-89.3]) for the experimental group (I²=0%). The mean surgical failure rate for the control group was 5.1% (95% CI [4.7-5.6%]), compared to 3.2% (95% CI [3.0-3.4%]) for the experimental group, with an odds ratio (OR) of 2.18 (95% CI [1.05–4.53], I²=0%, p = 0.738). The rate of secondary surgeries in the control group was 1.9% (95% CI [1.6–2.2]), while in the experimental group it was 10.7% (95% CI [9.4–12.1]), with an OR of 0.12 (95% CI [0.03–0.54], I²=63.1%, p = 0.028). Conclusion: The combination of MPFLR and TTO for treating PFI yields knee joint function comparable to that achieved with MPFLR alone. The approach does not elevate the failure rate of the surgery or the incidence of other adverse events. However, the combined approach may prolong the postoperative rehabilitation process and typically requires removal of internal fixation devices, resulting in a higher rate of secondary surgeries. [ABSTRACT FROM AUTHOR]

Primary patellar dislocation has a certain recurrence rate after either conservative or surgical treatment, and the optimal treatment for patients with primary patellar dislocation of different ages remains unclear. This study aims to compare the clinical efficacy of surgical and conservative treatments for primary patellar dislocation across different age groups. According to the Preferred Reporting Items for Systematic Reviews and Meta‐analyses (PRISMA) checklist, we conducted a systematic search for randomized controlled trials. We searched the PubMed, EMBASE, Cochrane Library, and Web of Science databases for randomized controlled trials of primary patellar dislocation treated surgically or conservatively up to January 2023. Data searching, extraction, analysis, and quality assessment were carried out in accordance with the Cochrane Collaboration guidelines. A total of nine studies with 433 patients were included in our study. There was no statistically significant difference between the two treatment modalities in terms of Kujala score, pain score, patient satisfaction, reoperation, and Tegner score. The rate of re‐dislocation after surgical treatment is lower than that after conservative treatment. Subgroup analysis based on mean age showed that when the age was >20 years, Kujala scores were higher after surgical treatment than after conservative treatment (p < 0.0001, 95% confidence interval [CI] = 10.41–21.30). When the age was ≤20 years, the difference in Kujala scores between the two treatment modalities was not statistically significant. When the age was >20 years, the recurrence rate of patellar dislocation was lower after surgical treatment than after conservative treatment (p = 0.009, 95% CI = 0.08–0.70). When the age was ≤20 years, the difference in the recurrence rate of patellar dislocation between the two treatment modalities was not statistically significant. When the age of patients with primary patellar dislocation is ≤20 years, both surgical and conservative treatments result in similar clinical outcomes. When the age is >20 years, better clinical outcomes can be achieved by opting for surgical treatment. Therefore, surgery may be a better option for patients with primary patellar dislocation whose age is >20 years. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to calculate the minimal detectable change (MDC) in the Norwich Patellar Instability score (NPI) and validate the score for Turkish-speaking individuals with patellar instability. Method: Sixty-four patients (mean age 21.87 ± 9.44 years) who had experienced at least one patellar dislocation during athletic activities participated in the study. The Turkish version of the NPI (NPI-T) was evaluated for reliability and internal consistency. The Minimal Detectable Change was calculated as an overall value for the participants. MDC was calculated based on the standard error of measurement (SEM) and the selected confidence level (ICC) for the study population. Pearson's correlations were examined to assess construct validity between the Kujala Patellofemoral Disorder score and the Lysholm Knee Score. Results: The MDC for the NPI-T was 17.29, with a SEM of 6.24. The score demonstrated high internal consistency, with a Cronbach's alpha value of 0.85, indicating substantial reliability. The consistency of measurements was excellent, with an ICC2,1 of 0.95. Additionally, the NPI-T score exhibited a strong negative correlation with both the Kujala (r = -0.85, p < 0.001) and Lysholm (r = -0.89, p < 0.001) scores. A floor effect was observed, but no ceiling effect was present. Conclusion: The study confirms that the NPI-T demonstrates strong psychometric properties, with high internal consistency and excellent reliability, as evidenced by its low MDC and SEM. The utility of the NPI-T as a reliable and valid tool for evaluating patellar instability in patients with patellar dislocation, providing valuable insights for clinicians. [ABSTRACT FROM AUTHOR]

Background: Tibial tuberosity–trochlear groove distance (TT-TG) is often used as a primary metric for surgical decision-making in the treatment of patellofemoral instability (PFI), particularly when considering tibial tubercle transfer. Although TT-TG has high interrater reliability, it is prone to measurement differences caused by the alignment of the patient's leg in a scanner gantry, potentially influencing surgical decision-making. Quantification of this error within the clinical literature remains limited. Purpose: To quantify and specify the error in TT-TG caused by leg-scanner alignment by using detailed topographical landmarks and 3-dimensional (3D) analysis of computed tomography scans of patients with PFI. Study Design: Controlled laboratory study. Methods: Three-dimensional models of knees with PFI were created from computed tomography scans and used to identify TT-TG landmarks. TT-TG was measured using the established 2-dimensional (2D) and 3D methods. A model to estimate the differences between these 2 methods was created, and the orientation of the patients' legs in relation to scanner longitudinal axis was measured to validate this model via linear regression. Interrater reliability was calculated via intraclass correlation coefficients (ICC). Results: A total of 44 knees of patients with PFI were analyzed. Differences between the 2D and 3D methods ranged from -4.0 to 14.7 mm (mean ± SD, 2.7 ± 4.1 mm) with a root mean square difference of 4.8 mm. The TT-TG distance of the 2D method (19.8 ± 7.2 mm) was significantly (P =.045) longer than that of the 3D method (17.1 ± 4.9 mm). The variance of the 2D method was significantly larger than that of the 3D method. In total, 13 (29.5%) of the knees had a difference of >5 mm between 2D and 3D TT-TG. The estimation model had an adjusted r 2 value of 1.00 and a resulting root mean square difference of 0.21 mm. 3D TT-TGs interrater reliability was good to excellent (ICC, 0.94 [95 CI%, 0.81-0.98]). Conclusion: 3D TT-TG can be used to correct scanner-leg alignment errors, some of which are substantial when using only 2D TT-TG measurements. Clinical Relevance: The findings in this study suggest a need for caution and awareness of the potential effects of differences in alignment of the axes of the leg and scanner when using purely 2D TT-TG as a basis for surgical planning. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: The concept of Single Assessment Numeric Evaluation (SANE) has been introduced for several clinical entities; however, a validated SANE focusing on patients with patellofemoral instability has not been described. Purpose/Hypothesis: The purpose of this study was to investigate the expressiveness of SANE questions (SQs) for the assessment of patients experiencing patellofemoral instability. It was hypothesized that the complexity of patellofemoral instability cannot be demonstrated by a single question. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Between October 2022 and March 2023, 120 consecutive patients (male/female, 50/70; mean age, 23.9 ± 8.0 years; mean body mass index, 25.3 ± 5.1 kg/m2) with patellofemoral instability were assessed with the Banff Patella Instability Instrument 2.0 (BPII 2.0). Patients were randomized into 3 groups (40 patients each) and asked to answer 1 of 3 SQs: "How do you rate your knee joint if a completely stable kneecap means 100%?" (SQ 1), "How do you rate your knee joint if complete satisfaction means 100%?" (SQ 2), and "How do you rate your knee joint if complete normal function means 100%?" (SQ 3). Means ± standard deviations were compared using 1-way analysis of variance, the correlation between BPII 2.0 and each SQ was assessed by Pearson correlation, and Bland-Altmann analysis was performed to investigate biases of each SQ in comparison with BPII 2.0. Results: The mean BPII 2.0 score was 40.5 ± 16.8 points, and the mean results of SQ 1, SQ 2, and SQ 3 were 44.2% ± 26.0%, 42.6% ± 25.4%, and 44.2% ± 18.9%, respectively, without significant differences between the groups (all P >.05). The correlations between BPII 2.0 and SQ 1, SQ 2, and SQ 3 were high (r = 0.75; 95% CI, 0.58 to 0.86; P <.0001), low (r = 0.35; 95% CI, –0.05 to 0.6; P =.02), and low (r = 0.31; 95% CI, –0.002 to 0.56; P =.051), respectively. Bland-Altman analysis between BPII 2.0 and SQ 1, SQ 2, and SQ 3 revealed biases of −0.12 (SD, 17.1), –1.45 (SD, 24.4), and −8.0 (SD, 19.4), respectively. Conclusion: The SQ "How do you rate your knee joint if a completely stable kneecap means 100%?" demonstrated concurrent validity with the BPII 2.0 and may serve as a helpful tool to quickly assess patients with recurrent patellofemoral instability in a preoperative setting. [ABSTRACT FROM AUTHOR]

Purpose: This study aims to evaluate the application value of the tibial tubercle–trochlear groove distance (TT–TG distance) and tibial tubercle–midepicondyle distance (TT–ME distance) on CT images in patellofemoral instability, and further investigate the association between knee joint rotation angles and patellofemoral instability. Methods: We retrospectively analyzed CT image data of 59 patients with patellar dislocation (case group) and 39 normal knee joints (control group). We measured the TT–TG distance, TT–ME distance, and knee joint rotation angle (KJRA) of both groups, and the related indicators were analyzed using single-factor/multi-factor binary logistic stepwise regression analysis. Two senior radiologists were assigned to assess the inter-rater reliability. Interclass correlation coefficients (ICC) were calculated. Finally, we used receiver operating characteristic (ROC) curves to compare the diagnostic efficiency of these indicators in patellofemoral instability. Results: The results found significant differences between both groups in terms of TT–TG distance, TT–ME distance, KJRA angle, age, location, and gender (P < 0.05). In terms of inter-rater reliability, TT–TG distance and TT–ME distance ratios showed an excellent correlation between observers (TT–TG inter-rater ICC 0.969, TT–ME inter-rater ICC 0.955). Univariate logistic regression analysis indicated that except for location and gender, all other factors significantly affected patellofemoral instability (P < 0.05). The multivariate logistic regression analysis revealed that the TT–ME distance, age, and KJRA angle were statistically significant factors related to patellofemoral instability, with TT–ME distance being a risk factor for patellofemoral instability (OR value 1.572, P value 0.000). Moreover, the ROC curve analysis demonstrated that the diagnostic capability of the TT–ME distance for detecting patellofemoral instability was higher than that of the TT–TG distance and KJRA (AUC were 0.912, 0.851, and 0.735, respectively). Conclusion: The TT–ME distance, age, and knee joint rotation angle are factors that affect patellofemoral instability. The TT–ME distance has better diagnostic efficiency for patellofemoral instability compared to the TT–TG distance and knee joint rotation angle. [ABSTRACT FROM AUTHOR]

Abstract Purpose Tibial tubercle osteotomy (TTO) is often employed for certain patellofemoral instability (PFI) cases, though its indications and effectiveness are not widely accepted. This systematic review gathers recent studies comparing isolated medial patellofemoral ligament reconstruction (iMPFLR) to MPFLR combined with TTO in managing PFI and to offer recommendations for clinicians when selecting TTO. This review proposes that MPFLR combined with TTO is superior to iMPFLR and that the combined procedure does not increase the incidence of postoperative complications. Methods Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 (PRISMA 2020), extensive searches were performed on August 20, 2024, across PubMed/Medline, Embase, and Cochrane databases to locate relevant studies. Data on research protocols, participant characteristics (including epidemiological and radiographic features), functional scores, and complications were collected and examined. A meta-analysis was conducted to compare the outcomes between the two surgical techniques. Results This systematic review analyzed 10 studies involving 715 participants, divided into a control group (which underwent iMPFLR) and an experimental group (which underwent MPFLR combined with TTO). In the control group, the incidence of severe trochlear dysplasia before surgery was 68.3% (95% CI [67.3-69.3%]), and the mean preoperative tibial tubercle to trochlear groove distance (TT-TG) was 16.1 mm (95% CI [15.8–16.3]). In the experimental group, both were respectively 79.1% (95% CI [77.5–80.7]) and 20.2 mm (95% CI [20.0-20.4]). Eight studies (80%) reported postoperative Kujala scores, with an average score of 85.1 (95% CI [84.4–85.9]) for the control group and 85.4 (95% CI [84.9–85.9]) for the experimental group (I²=22.7%). Four studies (40%) reported postoperative Lysholm scores, with an average score of 89.4 (95% CI [88.9–89.9]) for the control group and 89.1 (95% CI [89.0-89.3]) for the experimental group (I²=0%). The mean surgical failure rate for the control group was 5.1% (95% CI [4.7-5.6%]), compared to 3.2% (95% CI [3.0-3.4%]) for the experimental group, with an odds ratio (OR) of 2.18 (95% CI [1.05–4.53], I²=0%, p = 0.738). The rate of secondary surgeries in the control group was 1.9% (95% CI [1.6–2.2]), while in the experimental group it was 10.7% (95% CI [9.4–12.1]), with an OR of 0.12 (95% CI [0.03–0.54], I²=63.1%, p = 0.028). Conclusion The combination of MPFLR and TTO for treating PFI yields knee joint function comparable to that achieved with MPFLR alone. The approach does not elevate the failure rate of the surgery or the incidence of other adverse events. However, the combined approach may prolong the postoperative rehabilitation process and typically requires removal of internal fixation devices, resulting in a higher rate of secondary surgeries.

Background: Patellofemoral instability is associated with chondral injuries to the patella, trochlea, and lateral femoral condyle. Although studies have demonstrated an association between patellar dislocations and chondral injuries, the influence of the number of dislocations on chondrosis is not established. Purpose: To elucidate the precise association between the number of patellar dislocation events and the severity of chondral injuries in a multicenter cohort study at the time of patellar stabilization procedures. Study Design: Cross-sectional study; Level of evidence, 2. Methods: A prospective multicenter cohort study (JUPITER [Justifying Patellar Instability Treatment by Early Results]) database was queried for cases of primary patellofemoral instability procedures from December 2016 to September 2022. Cartilage lesions were classified using the International Cartilage Repair Society (ICRS) classification system during an arthroscopic or open evaluation (direct visualization), with grades 2 to 4 considered abnormal. The number of dislocations was categorized as 1, 2-5, and >5. Categorical variables were compared with the chi-square test, and binary logistic regression was performed to identify predictors of the presence of chondral lesions. Results: A total of 938 knees (mean age, 16.2 ± 3.8 years; 61.4% female) were included, with 580 (61.8%) demonstrating a chondral injury. The most affected region was the patella (n = 498 [53.1%]), followed by the lateral femoral condyle (n = 117 [12.5%]) and trochlea (n = 109 [11.6%]). There were no differences in the presence (P =.17) or grade (P =.63) of patellar lesions by the number of dislocations. Patients with >5 dislocations more frequently had trochlear chondral lesions (19.8%) compared with those with fewer dislocations (1, 7.6%; 2-5, 11.0%; P <.001). More dislocations were also associated with a higher proportion of ICRS grade 2 to 4 trochlear lesions (>5, 15.3%; 2-5, 10.0%; 1, 6.9%; P =.015). Combined patellar and trochlear lesions were also more common in those with >5 dislocations (P =.001). In multivariable regression, >5 dislocations was the only variable predictive of a trochlear lesion (odds ratio, 3.03 [95% CI, 1.65-5.58]; P <.001). Conclusion: This large prospective cohort study demonstrated that recurrent patellar dislocations can lead to more severe chondral damage in specific locations in the knee. More than 5 dislocations was associated with a >3-fold increase in the incidence and severity of trochlear chondral injuries. There were no differences in the presence or grade of patellar lesions by the number of dislocations. These findings should caution surgeons regarding prolonged nonoperative treatment. [ABSTRACT FROM AUTHOR]

Medial patellofemoral ligament (MPFL) reconstruction, typically used to restore stability to the patellofemoral joint after dislocation, often requires extensive rehabilitation to address acute impairment related to surgical intervention and also underlying non-anatomical deficits that may have contributed to the index injury. Rehabilitation guidelines, including objective functional performance assessment criteria, are lacking in the literature. We sought to summarize the clinical guidelines for rehabilitation and return to activity assessment after MPFL reconstruction as advocated by the member organizations of the Pediatric Research in Sports Medicine (PRiSM) Patellofemoral Research Interest Group (PF-RIG). We obtained and reviewed MPFL rehabilitation guidelines from 11 member organizations of the PRiSM PF-RIG, extracting information on weight-bearing advancement, bracing, use of supplemental strengthening modalities, and any objective criteria for advancing rehabilitation phases. We found highly variable agreement among guideline parameters at each treatment stage, with time-based criteria most widely used for early progression. Although functional metrics like strength or movement tests were more widely used in later phases of rehabilitation, there was substantial variation in testing mode and level of acceptable performance. Our review found that significant variability exists in current practice among PRiSM and PF-RIG member institutions regarding rehabilitation standards after MPFL reconstruction. Although we found broad consensus that objective strength or performance criteria should be employed to establish a better framework for clinical decision-making, most current guidelines lack standardization and sufficient detail to guide ideal clinical practice. [ABSTRACT FROM AUTHOR]

Pediatric patellar instability can impair function and restrict activity participation. If left untreated, it can lead to a degenerative knee. The incidence of patellar dislocations is highest in adolescents between 10 and 17 years of age; more than half of all first-time patellar dislocations occur during sports. This article reviews the evidence of risk factors for traumatic patellar instability, surgical interventions, and return-to-sport (RTS) considerations for pediatric and adolescent athletes. Anatomic risk factors for patellar instability in pediatric and adolescent patients include trochlear dysplasia, elevated tibial tuberosity-trochlear groove (TT-TG) distance, patella alta, genu valgum, femoral anteversion and tibial torsion, and hyperlaxity. [ABSTRACT FROM AUTHOR]

Background: It remains unclear which subset of patients with recurrent patellofemoral instability would benefit from a concomitant bony realignment procedure in addition to a medial patellofemoral ligament (MPFL) reconstruction. Purpose: To provide midterm results for patients who underwent an isolated MPFL reconstruction as part of an ongoing prospective trial. Study Design: Case series; Level of evidence, 4. Methods: Patients with recurrent patellar instability were prospectively enrolled in an institutional registry beginning in March 2014. Exclusion criteria included history of a previous surgery for patellar instability, an off-loadable (inferior/lateral) chondral defect, anterior knee pain ≥50% of their chief complaint, and a "jumping J" sign. All patients underwent primary, unilateral, isolated MPFL reconstruction regardless of their bony anatomic characteristics. Patient-reported outcome measures (PROMs), episodes of recurrent instability, and ability to return to sport were obtained annually. Radiographic measurements of baseline radiographs and MRI were obtained at baseline. Results: A total of 138 patients underwent isolated MPFL reconstruction between March 2014 and December 2019. The mean radiographic measurements were tibial tubercle–trochlear groove, 15.1 ± 4.9 mm; Caton-Deschamps index, 1.14 ± 0.16; patellar trochlear index, 46.9% ± 15.1%; trochlear depth index, 2.5 ± 1.2 mm; tibial tubercle to lateral trochlear ridge, −8.4 ± 5.7 mm; and patellar tendon to lateral trochlear ridge, 5.7 ± 6.2 mm. Trochlear dysplasia, defined as a trochlear depth index <3 mm, was present in 79/125 (63%) patients. A total of 50 patients reached ≥5 years, of whom 40 (80%) completed follow-up PROMs. A total of 119 patients reached ≥2 years, of whom 89 (75%) completed follow-up PROMs. Six patients (5%) reported recurrent instability with a mean time of 2.97 years after surgery. All PROMs improved over time except for the Pediatric Functional Activity Brief Scale (Pedi-FABS), which had no change. At 2 years, the mean changes from baseline for Knee injury and Osteoarthritis Outcome Score (KOOS) Quality of Life subscale (QOL), Pedi-FABS, International Knee Documentation Committee (IKDC) score, KOOS Physical Function Short Form (PS), and Kujala score were 42.1, 0.6, 35.1, –23.5, and 32.3, respectively. All changes had P values <.001 except for Pedi-FABS, which showed no change and had P >.999. At 5 years, the mean changes from baseline for KOOS-QOL, Pedi-FABS, IKDC, KOOS-PS, and Kujala score were 42.6, –2.8, 32.6, –21.5, and 31.6, respectively. All changes had P values <.001 except for Pedi-FABS, which showed no change and had P >.453. In total, 89% of patients returned to sport with a mean of 9.1 months. Conclusion: Midterm outcomes for patients who underwent isolated MPFL reconstruction were favorable and were maintained at 5 years. Outcomes for the expanded cohort of patients with a minimum 2-year follow-up support previously published results. [ABSTRACT FROM AUTHOR]

Background: Medial patellofemoral ligament (MPFL) reconstruction is considered by many to be the gold standard to treat lateral patellar instability; however, some investigators have reported good clinical results after isolated medial quadriceps tendon–femoral ligament (MQTFL) reconstruction or a combined MPFL/MQTFL reconstruction. A handful of studies have preliminarily investigated the biomechanical consequences of these various medial patellar stabilizing procedures. Despite this, no existing study has included multiple medial patellofemoral complex (MPFC) reconstructions and assessment of lateral patellar translation at distinct flexion angles. Hypothesis: Combined MPFL/MQTFL reconstruction would restore patellofemoral contact areas, forces, and kinematics closest to the native state compared with isolated reconstruction of the MPFL or MQTFL alone. Study Design: Controlled laboratory study. Methods: Ten adult cadaveric knee specimens were prepared and analyzed under 5 different conditions: (1) intact state, (2) transected MPFC, (3) isolated MPFL reconstruction, (4) isolated MQTFL reconstruction, and (5) combined MPFL/MQTFL reconstruction. Patellar tilt, lateral patellar translation, patellofemoral contact forces, and patellofemoral contact areas were measured in each condition from 0° to 80° through simulated knee flexion using a custom servohydraulic load frame with pressure sensor technology and a motion capture system for kinematic data acquisition. Results: The isolated MPFL, isolated MQTFL, and combined MPFL/MQTFL reconstruction conditions produced significantly less lateral patellar tilt compared with the transected MPFC state (P <.05). No statistically significant differences were found when each reconstruction technique was compared with the intact state in patellar tilt, lateral patellar translation, contact forces, and contact areas. Conclusion: All 3 reconstruction techniques (isolated MPFL reconstruction, isolated MQTFL reconstruction, and combined MPFL/MQTFL reconstruction) restored native knee kinematics, contact forces, and contact areas without overconstraint. Clinical Relevance: Isolated MPFL reconstruction, isolated MQTFL reconstruction, and combined MPFL/MQTFL reconstruction all restore patellofemoral stability comparable with the intact MPFC state without the overconstraint that could be concerning for increasing risk of patellofemoral arthritis. [ABSTRACT FROM AUTHOR]

Purpose: Patellofemoral joint instability (PFJI) can surgically be treated with a multitude of approaches, depending on the underlying pathology. In the presence of increased femoral anteversion, some authors have reported good results with a derotational distal femoral osteotomy (DeDFO). The purpose of the study was to investigate the indications, outcomes and complication rate of DeDFO for PFJI. Methods: A systematic review was performed according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta‐analyses) by searching Medline, Embase, Web of Science and Cochrane Library databases through 1 December 2023. Included were levels 1–4 clinical studies of skeletally mature patients undergoing a DeDFO for PFJI irrespective of concomitant procedures. Study characteristics, indications, radiological and clinical outcomes, surgical technique and concomitant procedures, re‐dislocation and complication rate were all analysed, as was methodological quality. Results: A total of 12 studies including 310 patients (325 knees) were included. Three studies were cohort studies, all others were case series. The mean patient age across the studies was 22 years, and the mean follow‐up was 29.4 months. Femoral anteversion cut‐off was between 20° and 30°. Every study included at least one concurrent soft tissue, bony or combined procedure. Across all studies, one case of re‐dislocation was reported (0.3%) and four implant or osteotomy‐related complications (1.2%) were reported. All studies reported a statistically significant increase in clinical scores. Conclusion: This systematic review of DeDFO for patellofemoral instability in the presence of increased femoral anteversion demonstrates promising clinical results and an extremely low dislocation and complication rate. The heterogeneity of the cut‐off in anteversion and concomitant procedures, especially tibial tubercle osteotomy with seemingly identical results, indicates the need for high‐quality evidence for treating patellofemoral instability. Based upon this systematic review, we strongly recommend that DeDFO be added to the 'menu à la carte' of PFJI. Level of Evidence: Level III Systematic Review. [ABSTRACT FROM AUTHOR]

Background: Torsional malalignment of the femur and/or tibia is associated with patellar maltracking, and torsional osteotomies have shown to improve clinical symptoms. In patients with severe torsional malalignment, a double-level torsional osteotomy may be necessary. Indications: Symptomatic torsional malalignment leading to patellofemoral maltracking associated with anterior knee pain and/or patellofemoral instability. Technique Description: A double-level torsional osteotomy correcting both increased internal femoral torsion and increased external tibial torsion, is described. Meticulous preoperative deformity analysis and planning of the osteotomy is mandatory. An arthroscopy of the knee is performed first to evaluate the patellofemoral joint and patellar tracking. Tibial torsional correction is performed by a lateral approach. A biplanar osteotomy is performed, and the amount of torsional correction is controlled by 2 Schanz screws. Osteosynthesis can be done via a bended 5-hole DC-Plate or an angle-stable plate. The femoral osteotomy is performed by a medial approach. A uniplanar osteotomy is performed perpendicular to the mechanical axis of the femur. The amount of torsional correction is controlled by 2 Schanz screws. Osteosynthesis is achieved by an angle-stable plate. Results: Double-level torsional osteotomy has been shown to be an effective treatment for patients with patellar dislocation or subluxation associated with severe torsional malalignment. In a series of 18 patients, double-level osteotomy led to improved patellofemoral stability, decreased pain, and increases subjective outcome scores. Discussion/Conclusion: In patients with patellofemoral problems caused by a combined increased tibial external torsion and increased femoral internal torsion, a double-level torsional osteotomy is able to correct torsional angles to normal. Available clinical data on this procedure are promising. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication. [ABSTRACT FROM AUTHOR]

Abstract This study performed three-dimensional (3D) magnetic resonance imaging (MRI)-based statistical shape analysis (SSA) by comparing patellofemoral instability (PFI) and normal femur models, and developed a machine learning (ML)-based prediction model. Twenty (19 patients) and 31 MRI scans (30 patients) of femurs with PFI and normal femurs, respectively, were used. Bone and cartilage segmentation of the distal femurs was performed and subsequently converted into 3D reconstructed models. The pointwise distance map showed anterior elevation of the trochlea, particularly at the central floor of the proximal trochlea, in the PFI models compared with the normal models. Principal component analysis examined shape variations in the PFI group, and several principal components exhibited shape variations in the trochlear floor and intercondylar width. Multivariate analysis showed that these shape components were significantly correlated with the PFI/non-PFI distinction after adjusting for age and sex. Our ML-based prediction model for PFI achieved a strong predictive performance with an accuracy of 0.909 ± 0.015, and an area under the curve of 0.939 ± 0.009 when using a support vector machine with a linear kernel. This study demonstrated that 3D MRI-based SSA can realistically visualize statistical results on surface models and may facilitate the understanding of complex shape features.

Objective The risk of osteochondral fracture (OCF) after patellar dislocation has been shown to be related to patellofemoral anatomy, but its relationship to patellar morphology remains unknown. The aim of this study was to investigate the associations between patellar morphology and the risk of OCF after patellar dislocation. Methods A total of 140 patients with patellar dislocation between January 2018 and June 2023 were enrolled in this study and divided into two groups. Sixty‐five patellar dislocation patients with OCF were included in the OCF group, while 75 patellar dislocation patients without OCF were included in the non‐OCF group. Computed tomography was used to compare measurements of patellar morphology including Wiberg classification, patellar width and thickness, Wiberg angle, Wiberg index, facet ratio, lateral patellar facet angle, and patellar tilt angle. A logistic regression model was performed to evaluate the correlations between patellar morphology and the risk of OCF after patellar dislocation. Receiver operating characteristic curves were used to calculate the area under the curve (AUC) and determine the diagnostic values of patellar morphology for OCF after patellar dislocation. Subgroup analyses for gender and age were conducted to compare the differences in patellar morphology of PD patients. Results Wiberg angle was significantly lower in the OCF group (p = 0.017), while Wiberg index (p = 0.002) and facet ratio (p = 0.023) were significantly higher in the OCF group. According to the results of logistic regression analysis, Wiberg angle (odds ratio [OR] = 0.96, p = 0.022) and Wiberg index (OR = 1.105, p = 0.032) were the final relevant factors for the occurrence of OCF after patellar dislocation. The AUC was 0.622 (95% confidence interval [CI]: 0.529–0.714) for Wiberg angle, 0.65 (95% CI: 0.558–0.742) for Wiberg index, and 0.702 (95% CI: 0.615–0.788) for the combination of Wiberg angle plus Wiberg index. Conclusion Wiberg angle and Wiberg index were independent risk factors for the occurrence of osteochondral fracture after patellar dislocation. Moreover, Wiberg angle, Wiberg index, and the combination of Wiberg angle plus Wiberg index had good predictive diagnostic value for the occurrence of OCF after patellar dislocation.

This study performed three-dimensional (3D) magnetic resonance imaging (MRI)-based statistical shape analysis (SSA) by comparing patellofemoral instability (PFI) and normal femur models, and developed a machine learning (ML)-based prediction model. Twenty (19 patients) and 31 MRI scans (30 patients) of femurs with PFI and normal femurs, respectively, were used. Bone and cartilage segmentation of the distal femurs was performed and subsequently converted into 3D reconstructed models. The pointwise distance map showed anterior elevation of the trochlea, particularly at the central floor of the proximal trochlea, in the PFI models compared with the normal models. Principal component analysis examined shape variations in the PFI group, and several principal components exhibited shape variations in the trochlear floor and intercondylar width. Multivariate analysis showed that these shape components were significantly correlated with the PFI/non-PFI distinction after adjusting for age and sex. Our ML-based prediction model for PFI achieved a strong predictive performance with an accuracy of 0.909 ± 0.015, and an area under the curve of 0.939 ± 0.009 when using a support vector machine with a linear kernel. This study demonstrated that 3D MRI-based SSA can realistically visualize statistical results on surface models and may facilitate the understanding of complex shape features. [ABSTRACT FROM AUTHOR]

Background: Literature is sparse on outcome comparisons between different trochleoplasty techniques in the treatment of patella instability. To date, it is unclear whether there is a technique that offers superior outcomes. This systematic review and meta-analysis aims to compare and evaluate the outcomes of trochleoplasty techniques in the treatment of patellofemoral instability in trochlea dysplasia to establish whether there is an ideal choice of trochleoplasty technique for superior outcomes. Methods: 21 studies involving 880 knees were included. The mean age of the patients was 21.7 years (range 8–49 years). Mean follow-up timeframe of 43.5 months (range 8.8–100 months). Clinical outcomes assessed included rates of recurrence of patellofemoral dislocation, patient satisfaction, Kujala score, International Knee Documentation Committee (IKDC) score, Tegner score, and Lysholm score. Egger's test showed no publication bias across all outcomes assessed. Results: Favourable results were seen across all outcomes assessed and patient satisfaction. Improvements were seen with Kujala, IKDC, and Lysholm scores. Tegner scores showed good return to function. Post-operative dislocation and complication rates were low across the different techniques. Meta-regression for Kujala and IKDC scores showed good outcomes regardless of trochleoplasty technique used (Kujala, p = 0.549, relative risk 492.06; IKDC, p = 0.193, RR 0.001). The exact risk that trochleoplasty poses to the cartilage remains uncertain, as no study had a conservatively managed arm for comparison. Conclusions: Trochleoplasty yielded good outcomes irrespective of technique used with no clear superiority demonstrated in any technique in terms of outcome scores, satisfaction, post-operative dislocation rates or complications. [ABSTRACT FROM AUTHOR]

Objective: The risk of osteochondral fracture (OCF) after patellar dislocation has been shown to be related to patellofemoral anatomy, but its relationship to patellar morphology remains unknown. The aim of this study was to investigate the associations between patellar morphology and the risk of OCF after patellar dislocation. Methods: A total of 140 patients with patellar dislocation between January 2018 and June 2023 were enrolled in this study and divided into two groups. Sixty‐five patellar dislocation patients with OCF were included in the OCF group, while 75 patellar dislocation patients without OCF were included in the non‐OCF group. Computed tomography was used to compare measurements of patellar morphology including Wiberg classification, patellar width and thickness, Wiberg angle, Wiberg index, facet ratio, lateral patellar facet angle, and patellar tilt angle. A logistic regression model was performed to evaluate the correlations between patellar morphology and the risk of OCF after patellar dislocation. Receiver operating characteristic curves were used to calculate the area under the curve (AUC) and determine the diagnostic values of patellar morphology for OCF after patellar dislocation. Subgroup analyses for gender and age were conducted to compare the differences in patellar morphology of PD patients. Results: Wiberg angle was significantly lower in the OCF group (p = 0.017), while Wiberg index (p = 0.002) and facet ratio (p = 0.023) were significantly higher in the OCF group. According to the results of logistic regression analysis, Wiberg angle (odds ratio [OR] = 0.96, p = 0.022) and Wiberg index (OR = 1.105, p = 0.032) were the final relevant factors for the occurrence of OCF after patellar dislocation. The AUC was 0.622 (95% confidence interval [CI]: 0.529–0.714) for Wiberg angle, 0.65 (95% CI: 0.558–0.742) for Wiberg index, and 0.702 (95% CI: 0.615–0.788) for the combination of Wiberg angle plus Wiberg index. Conclusion: Wiberg angle and Wiberg index were independent risk factors for the occurrence of osteochondral fracture after patellar dislocation. Moreover, Wiberg angle, Wiberg index, and the combination of Wiberg angle plus Wiberg index had good predictive diagnostic value for the occurrence of OCF after patellar dislocation. [ABSTRACT FROM AUTHOR]

Background: Patellofemoral instability commonly occurs during sports activities. The return to sports (RTS) rate for pediatric patients after bilateral medial patellofemoral ligament reconstruction (MPFLR) is unknown. Purpose/Hypothesis: The purpose of this study was to evaluate RTS outcomes for pediatric patients undergoing bilateral MPFLR. It was hypothesized that (1) fewer pediatric patients would RTS after bilateral MPFLR compared with unilateral MPFLR and that (2) for those in the bilateral cohort who were able to RTS, fewer patients would attain the same level of play as or higher level than the preinjury level. Study Design: Cohort study; Level of evidence, 3. Methods: We prospectively collected RTS data on retrospectively identified matched cohorts of patients aged ≤18 years who underwent unilateral and bilateral MPFLR. We matched each participant with bilateral MPFLR at a 1 to 2 ratio with a participant with unilateral MPFLR by concomitant procedure, age, and sex. Postoperative complications and preoperative imaging measurements were collected from medical records. Patient-reported outcomes were obtained using a current Single Assessment Numeric Evaluation score collected at the time of primary outcome data. Results: We matched 16 participants (mean age, 14 years) who underwent bilateral MPFLR to 32 participants (mean age, 14.3 years) in a corresponding unilateral MPFLR cohort. We found a significant decrease in RTS rates for pediatric patients after bilateral MPFLR when compared with unilateral MPFLR (69% vs 94%; P =.03). Among those who returned to sports, there was no difference in the level of play achieved. For participants who did not RTS or returned at a lower level of play after bilateral MPFLR, 57% cited fear of reinjury as the primary reason. There were no differences in postoperative complications or current Single Assessment Numeric Evaluation scores between cohorts. The bilateral cohort had a significantly higher Caton-Deschamps index compared with the unilateral cohort, although the absolute difference was small (1.3 vs 1.2; P =.005). Conclusion: We found that pediatric patients have a lower RTS rate after bilateral MPFLR when compared with a matched unilateral MPFLR cohort. No differences in the level of play were achieved among those who returned to sports. Fear of reinjury was a commonly cited reason for not returning to sports. [ABSTRACT FROM AUTHOR]

Purpose: Implant‐mediated guided growth (IMGG) is used to address coronal plane deformity in skeletally immature patients. Few studies have reported on IMGG and simultaneous medial patellofemoral ligament (MPFL) reconstruction for paediatric patients with concurrent genu valgum and patellofemoral instability (PFI). This study aimed to report on the outcomes of these simultaneous procedures. Materials and Methods: This was a retrospective review of paediatric patients undergoing simultaneous MPFL reconstruction and IMGG between 2016 and 2023. Mechanical lateral distal femoral angle (mLDFA), hip–knee–ankle angle (HKA) and mechanical axis deviation (MAD) were measured on full‐length hip‐to‐ankle plain radiographs. Measurements were taken preoperatively, prior to implant removal and/or at final follow‐up with minimum 1‐year clinical follow‐up. Results: A total of 25 extremities in 22 patients (10 female) underwent simultaneous IMGG and MPFL reconstruction. The mean age at surgery was 12.6 ± 1.7 years. The mean duration of implant retention was 18.6 ± 11.3 months. Nineteen extremities (76%) underwent implant removal by final follow‐up. Preoperative HKA corrected from a mean of 5.8 ± 2.3° to −0.8 ± 4.5° at implant removal or final follow‐up (p < 0.001), with mLDFA and MAD similarly improving (both p < 0.001). HKA corrected a mean of 0.7 ± 0.9° per month, while mLDFA and MAD corrected a mean of 0.5 ± 0.6°/month and 2 ± 3 mm/month, respectively. At the time of implant removal or final follow‐up, 88% of patients demonstrated alignment within 5° of neutral. Only one extremity experienced subsequent PFI (4%). For 14 patients who underwent implant removal with further imaging at a mean of 7.8 ± 4.9 months, only one patient (7%) had a valgus rebound to an HKA > 5°. Conclusion: Simultaneous MPFL reconstruction and IMGG provided successful correction of lower extremity malalignment with only one recurrence of PFI. This approach is a reliable surgical option for skeletally immature patients with genu valgum and PFI. Level of Evidence: Level 4 case series. [ABSTRACT FROM AUTHOR]

Purpose: The success of medial patellofemoral ligament (MPFL) reconstruction is closely linked to the precise positioning of the femoral tunnel. Intraoperative fluoroscopy is commonly utilized to identify the MPFL footprint. This study aimed to ascertain the most accurate fluoroscopic method among the five previously described methods used to determine the MPFL femoral footprint. Materials and methods: Using 44 well-preserved dry femur bones, the MPFL femoral insertion site was demarcated using anatomical bony landmarks, namely the center of the saddle sulcus between the medial epicondyle, adductor tubercle and gastrocnemius tubercle. Fluoroscopic true lateral knee images were acquired and measurements taken, referencing established methods by Schottle et al., Redfern et al., Wijdicks et al., Barnett et al., and Kaipel et al. The distance between anatomic and fluoroscopic MPFL footprints was then measured on digital fluoroscopic images. The accuracy of the locations was compared using a margin of error of 5 and 7 mm. Results: The Schottle method consistently emerged superior, showcasing the smallest mean distance (3.2 ± 1.2 mm) between the anatomic and radiographic MPFL footprints and a high in-point detection rate of 90.9% under 5 mm criteria. While the Redfern method displayed perfect accuracy (100%) within the 7 mm criteria, the Schottle method also performed 97.7% accuracy. Conclusions: For intraoperative identification of the MPFL footprint using fluoroscopy, the Schottle method is the most consistent and accurate among the assessed methods. Thus, its accuracy in detecting the MPFL footprint makes it recommended for MPFLR to ensure optimal outcomes. Level of evidence: Level IV, cadaveric study. [ABSTRACT FROM AUTHOR]

Introduction: Numerous indices for patella height measurement are described in the literature; however, there is not a universally accepted 'gold standard'. Choice of indices varies depending on personal preference and previous experience, making it difficult to compare results between studies. The aims of this study were to assess the correlation between different patella height indices and generate statistically derived formulae that can be used to predict the value of one patella height ratio when another is known. Materials and Methods: Patients with patellofemoral instability were radiologically evaluated using both X-ray and Magnetic Resonance Imaging (MRI) of the knee. Two observers measured six validated patella height indices at two separate time intervals. All measurements were aggregated together and a mean average for each patella height ratio was calculated. These results were then statistically analysed using Pearson product-moment correlation and linear regression tests. Results: Forty-four patients were included in the study. A statistically significant correlation was found between the majority of patella height ratios. On X-ray, the strongest correlation (r = 0.92, p < 0.001) and regression (R2 = 0.85, p < 0.001) coefficients were between the Blackburne-Peel and Caton-Dechamps ratios, with the formula; CD = 0.20 + (0.95xBP). On MRI, the strongest correlation (r = − 0.84, p < 0.001) and regression (R2 = 0.71, p < 0.001) coefficients were between the Patellophyseal index and Patellotrochlear index, with the formula; PP = 1.02-(1.10xPT). Conclusion: The formulae produced in this study can predict the value of one patella height ratio when the results of another are known. This could facilitate systematic reviews and meta-analyses by allowing the pooling together of data from many studies. [ABSTRACT FROM AUTHOR]

Purpose: There are limited studies that have reported the middle- to long-term outcomes of combined procedures consisting of more than two procedures for patellofemoral instability. The current study aims to investigate and report the middle- to long-term outcomes of a combination procedure of tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release for patellofemoral instability in patients aged 18 years and below. Methods: In the cohort study, all patients aged 18 years old or younger who underwent a combination procedure of tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release for recurrent patellofemoral instability were included. Results: A total of 21 patients were included in the study. All patients had no further patellofemoral dislocation, pain and apprehension following the 4-in-1 surgery (p < 0.01). There was a significant improvement in the Kujala score from 36.1 (SD 12.9) pre-operatively to 93.1 (SD 3.6) post-operatively (p < 0.001). The patients also had a statistically significant improvement in their radiological factors, including the patellar tilt angle (p < 0.001), sulcus angle (p = 0.001), trochlear groove depth (p = 0.041), tibial tubercle-trochlear groove distance (p < 0.001) and Caton–Deschamps index (p = 0.001). Conclusion: A combination procedure of tibial tubercle transfer, medial patellofemoral ligament reconstruction, trochleoplasty and lateral release leads to good middle- to long-term subjective, functional and radiographic outcomes for patients with recurrent patellofemoral instability and underlying predisposing factors of increased TT-TG distance of more than 20 mm, Dejour B or D trochlear dysplasia and medial patellofemoral ligament rupture. Level of evidence: IV. [ABSTRACT FROM AUTHOR]

Background: Tibial tubercle osteotomy (TTO) is a well-established surgical treatment option for patellofemoral instability and pain. TTO with distalization (TTO-D) is indicated for patients with patellofemoral instability, patellar malalignment, and patella alta. The current literature demonstrates several complications that may be associated with TTO, with reportedly higher rates of complications associated with TTO-D. Purpose: To analyze and compare complication rates after TTO without distalization (TTO-ND) and TTO-D and assess risk factors associated with complications. Study Design: Cohort study; Level of evidence, 3. Methods: All skeletally mature patients who underwent TTO with or without distalization by a single surgeon between September 2014 and May 2023 with a minimum of 6 months of clinical follow-up were retrospectively reviewed. Patient factors, surgical indications, perioperative data, and complications were collected via a retrospective review of electronic medical records. Concomitant procedures were categorized as intra-articular, extra-articular, and osteotomies. Results: A total of 251 TTOs (117 TTO-D, 134 TTO-ND) were included in the study group. Postoperative complications were observed in 15 operations (6%), with arthrofibrosis as the most common complication (10 operations [4%]). TTO-D and TTO-ND had similar rates of complication (5% vs 7%; P =.793). Clinical nonunion was observed in 3 operations (3%) in the TTO-D cohort and 1 operation (1%) in the TTO-ND cohort. In the TTO-D cohort, concomitant intra-articular procedures were significantly associated with an increased likelihood of complications in a univariate model. In the TTO-ND cohort, an increased tourniquet time was significantly associated with an increased likelihood of complications in a univariate model. For all TTOs as well as the TTO-D and TTO-ND cohorts, there were no significant associations between patient or surgical variables in a multivariate model. Conclusion: TTO with and without distalization is a safe procedure with low rates of complication. TTO-D was not associated with a higher rate of complications compared with TTO-ND. There was no association between complications and surgical variables for TTO procedures. [ABSTRACT FROM AUTHOR]

Instabilities and dislocations of the patella are highly debilitating. They lead to injuries of the joint cartilage, osteochondral fractures, recurrent instability, pain, loss of sports ability, reduced daily activity, and finally to patellofemoral osteoarthritis. Dysplasia of the patellar groove, other bony deformities, and damage to the ligaments stabilizing the patella are important causes of this progressive disease. The knowledge and therapeutic options surrounding this topic have significantly expanded in recent years. Both in acute situations and in cases of chronic recurrence, good diagnostics are essential to enable appropriate conservative or surgical treatment. Surgically, it is important to address relevant findings in terms of a „à la carte“ surgery. The most important procedures include bony corrections of the patellar groove, or trochleoplasties, as well as several other bony correction procedures. Equally important are reconstructions of the medial patellofemoral ligament, which is often damaged and represents the main band stabilizer of the patella. This CME article describes the essential diagnostic steps, different therapeutic concepts, and the results. [ABSTRACT FROM AUTHOR]

Objective: We aimed to evaluate the effectiveness of modified Aberdeen Weight-Bearing Test (Knee) (AWT-K) and KSS (Knee Society Score) comparing their correlations with the Tegner Lysholm (TL) score in patellar instability patients. Methods: Patients treated for patellar dislocation were divided into two groups. The first group consisted of patients operated on for patellar instability and the second group patients followed by conservative means. Duration of follow-up, age, gender, Caton-Deschamps in)dex, and type of surgical interventions were recorded. Since the TL scoring system was previously validated in the follow-up of patellar instability treatment, the compatibility of KSS and modified AWT-K scoring systems with the TL scoring system was evaluated and their effectiveness in the follow-up of patellar instability was examined. Results: A moderate correlation was found between TL and total KSS scores.However, when the relationship between KSS subgroups ES, SS, OKS, FAS and TL is examined; a weak and moderate correlation was found between the TL scoring system and OKS, SS, and FAS. When weak and non-correlated ES and SS were excluded, there was a strong correlation between TL score and mtKSS.There was a low correlation between TL scores and AWT-K 60-second average load difference and there was a low correlation between FA and AWT-K 60-second mean load difference and ratios. Conclusion: The weak correlation of the AWT-K test for weight-bearing on the knee with findings of KSS and the TL scoring system reveals that may not be an adequate follow-up instrument for patients with patellar instability in short-term follow ups. [ABSTRACT FROM AUTHOR]

Purpose: Patellofemoral instability (PFI) is a common condition that can be caused from multiple factors, including lower limb rotational malalignments. Determining precise criteria for performing corrective torsional osteotomy can be a daunting task due to the lack of consensus on normal and excessive values and the limited evidence‐based data in the postoperative results. The purpose was to assess the clinical, functional and imaging outcomes following derotational distal femoral osteotomy (DDFO) in patients with PFI and/or anterior knee pain (AKP) associated with lower limb rotational malalignments. Methods: Searches were conducted on PubMed, EMBASE and Web of Science databases up to October 2023. Studies reporting outcomes after DDFO in patients with PFI and/or AKP were eligible for the systematic review. The primary outcome was imaging metrics, especially femoral anteversion. Secondary outcomes included the patient‐reported outcome measures (PROMs) (clinical and functional). Quantitative synthesis involved the use of weighted averages to calculate pre‐ to postoperative mean differences (MD) and compare them against the minimal clinically important difference (MCID). Results: Ten studies (309 knees) were included with a mean follow‐up of 36.1 ± 11.7 months. Imaging outcomes consistently indicated the correction of femoral anteversion (MD = −19.4 degrees, 95% confidence interval: −20.1 to −18.7) following DDFO. PROMs showed significant improvements in most studies, exceeding the MCID. Patient satisfaction with the DDFO was high (93.3%). Conclusions: The DDFO was an effective treatment option for correcting excessive femoral anteversion in patients with PFI associated with clinically relevant functional and clinical improvement and a high satisfaction rate. Level of Evidence: Level IV, systematic review of level II–IV studies. [ABSTRACT FROM AUTHOR]

Abstract Purpose Patellofemoral joint instability (PFJI) can surgically be treated with a multitude of approaches, depending on the underlying pathology. In the presence of increased femoral anteversion, some authors have reported good results with a derotational distal femoral osteotomy (DeDFO). The purpose of the study was to investigate the indications, outcomes and complication rate of DeDFO for PFJI. Methods A systematic review was performed according to the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta‐analyses) by searching Medline, Embase, Web of Science and Cochrane Library databases through 1 December 2023. Included were levels 1–4 clinical studies of skeletally mature patients undergoing a DeDFO for PFJI irrespective of concomitant procedures. Study characteristics, indications, radiological and clinical outcomes, surgical technique and concomitant procedures, re‐dislocation and complication rate were all analysed, as was methodological quality. Results A total of 12 studies including 310 patients (325 knees) were included. Three studies were cohort studies, all others were case series. The mean patient age across the studies was 22 years, and the mean follow‐up was 29.4 months. Femoral anteversion cut‐off was between 20° and 30°. Every study included at least one concurrent soft tissue, bony or combined procedure. Across all studies, one case of re‐dislocation was reported (0.3%) and four implant or osteotomy‐related complications (1.2%) were reported. All studies reported a statistically significant increase in clinical scores. Conclusion This systematic review of DeDFO for patellofemoral instability in the presence of increased femoral anteversion demonstrates promising clinical results and an extremely low dislocation and complication rate. The heterogeneity of the cut‐off in anteversion and concomitant procedures, especially tibial tubercle osteotomy with seemingly identical results, indicates the need for high‐quality evidence for treating patellofemoral instability. Based upon this systematic review, we strongly recommend that DeDFO be added to the ‘menu à la carte’ of PFJI. Level of Evidence Level III Systematic Review.

Purpose: There are various anatomic risk factors for patellofemoral instability (PFI) that help guide surgical treatment, including the tibial tubercle to trochlear groove (TT‐TG) distance. However, no study has analysed the temporal changes in TT‐TG prior to surgical intervention. This study sought to understand the variations in TT‐TG over time for pediatric patients suffering from PFI prior to surgical intervention. The authors hypothesised that the TT‐TG would substantially change between time points. Methods: Patients undergoing medial patellofemoral ligament (MPFL) reconstruction between 2014 and 2019 by one of two fellowship‐trained orthopaedic surgeons were identified. Patients were included if they had two preoperative magnetic resonance imaging (MRI) performed on the same knee within 7.5 months of each other prior to any surgical intervention and had an initial TT‐TG greater than 10 mm. Results: After considering 251 patients for inclusion, 21 patients met the final inclusion criteria. The mean age was 14.5 ± 2.5 years and 61.9% were female. TT‐TG was initially noted to be 15.1 ± 1.8 mm. At mean time after sequential MRIs of 5.0 ± 1.9 months, TT‐TG was noted to be 16.7 ± 3.2 mm. The differences between initial and subsequent TT‐TG ranged from a 21.2% decrease to a 61.1% increase, with a mean difference of an 11.3% increase. Comparison between initial and subsequent TT‐TG values demonstrated a significant difference (p = 0.017). Change in tibiofemoral rotation ranged from −9.2° to 7.5°. When comparing the change in TT‐TG to change in tibiofemoral rotation, a significant correlation was found (p = 0.019). Conclusion: Despite only a mean time between MRIs of 5 months, variations in TT‐TG ranged from a decrease of 21.2% to an increase of 61.1%. The significant relationship between the changes in TT‐TG and changes in tibiofemoral rotation between MRIs suggest that TT‐TG measurements may vary due to variations in tibiofemoral rotation at the time of individual MRIs. Level of Evidence: Level IV. [ABSTRACT FROM AUTHOR]

Background: Distalization tibial tubercle osteotomy (TTO) is an effective treatment for improving patellar height in patients with patella alta associated with patellofemoral instability and cartilage lesions. The addition of a patellar tendon tenodesis has been suggested; nonetheless, concerns exist regarding possible increased patellofemoral cartilage stresses. Purpose: To evaluate pre- and postoperative patellar tendon length and alignment parameters on magnetic resonance imaging (MRI), as well as patient-reported outcome measures (PROMs) after distalization TTO without patellar tendon tenodesis. Study Design: Case series; Level of evidence, 4. Methods: Twenty skeletally mature patients who underwent distalization TTO with or without anteromedialization at our institution between December 2014 and August 2021 were included. All patients underwent pre- and postoperative MRIs of the affected knee. The Caton-Deschamps index (CDI), the axial and sagittal tibial tubercle–trochlear groove (TT-TG) distances, the distances from the tibial plateau to the patellar tendon insertion and the tibial tubercle, and the patellar tendon length were assessed. PROMs included the International Knee Documentation Committee Subjective Knee Evaluation Form, the Knee injury and Osteoarthritis Outcome Score–Quality of Life subscale, the Kujala Anterior Knee Pain Scale, and the Veterans RAND 12-Item Health Survey mental and physical component scores. Results: The mean patient age at surgery was 27.4 years (range, 14-42 years). Radiographic parameters demonstrated improved patellar height (CDI decreased from 1.36 to 1.11; P <.001) after distalization TTO. The distance from the tibial plateau to the patellar tendon insertion significantly decreased from 20.1 mm preoperatively to 17.9 mm postoperatively (P <.020), and the patellar tendon length decreased from 53.4 mm preoperatively to 46.0 mm postoperatively (P <.001). The patellar tendon insertion was not distalized after distalization TTO, likely because of scarring of the patellar tendon proximal to the osteotomy site. Patients demonstrated significant pre- to postoperative improvements on all PROMs (P ≤.024 for all). There were 4 (20%) complications—2 cases of arthrofibrosis, 1 postoperative infection, and 1 osteotomy delayed union. Conclusion: Distalization TTO without patellar tendon tenodesis was associated with improved radiographic outcomes and PROMs. It provides an additional tool for surgical management of patellofemoral pathology with associated patella alta. [ABSTRACT FROM AUTHOR]

Because kinematic alignment (KA) aligns femoral components in greater valgus and with less external rotation than mechanical alignment (MA), the trochlear groove of an MA design used in KA is medialized, which can lead to complications. Hence, a KA design has emerged. In this study, our primary objective was to quantify differences in trochlear morphology between the KA design and the MA design from which the KA design evolved. The KA and MA designs were aligned in KA on ten 3D femur-cartilage models. Dependent variables describing the morphology of the trochlea along the anterior flange, which extends proximal to the native trochlea, and along the arc length of the native trochlea, were determined, as was flange coverage. Along the anterior flange, the KA groove was significantly lateral proximally by 10 mm and was significantly wider proximally by 5 mm compared to the MA design (p < 0.0001). Along the arc length of the native trochlea, the KA groove was significantly lateral to the MA design by 4.3 mm proximally (p ≤ 0.0001) and was significantly wider proximally by 19 mm than the MA design. The KA design reduced lateral under-coverage of the flange from 4 mm to 2 mm (p < 0.0001). The KA design potentially mitigates risk of patellofemoral complications by lateralizing and widening the groove to avoid medializing the patella for wide variations in the lateral distal femoral angle, and by widening the flange laterally to reduce under-coverage. This information enables clinicians to make informed decisions regarding use of the KA design. [ABSTRACT FROM AUTHOR]

Patellofemoral instability (PFI) is a common disorder in children and adolescents. Surgical stabilization of the patella poses challenges in skeletally immature patients due to anatomical peculiarities at this stage, leading to the absence of an established standard reconstruction technique. Recently, there has been a notable interest in the medial patellofemoral complex (MPFC), encompassing the medial patellofemoral ligament (MPFL) and the medial quadriceps tendon femoral ligament (MQTFL), owing to their role in restricting lateral patellar displacement. This paper aims to describe the surgical technique employed by the author for reconstructing the medial patellofemoral complex with allograft in skeletally immature patients with patellofemoral instability. Study design: surgical technique. [ABSTRACT FROM AUTHOR]

Purpose: Trochlear dysplasia (TD) is one of the several factors that predispose to recurrent instability and long-term morbidity. Subclassification can aid in risk stratification with surgery and comparing case-cohort outcomes. The inter- and intra-observer agreement of the Oswestry-Bristol Classification (OBC) for TD has previously been demonstrated in adults but not in children. We aim to assess the inter- and intra-observer reliability of the OBC in skeletally immature patients. Methodology: This was a retrospective review of magnetic resonance imaging scans performed in children presenting with patellofemoral instability or recurrent dislocation. A total of 34 scans were graded according to the OBC by seven orthopedic surgeons in two rounds 6 weeks apart. All reviewers were blinded and scans were randomized. The observations from both rounds were compared for inter- and intra-rater reliability. Results: First-round observations showed low–moderate agreement between raters (mean kappa = 0.39). Second-round observations showed moderate agreement (mean kappa = 0.42). However, subanalysis using S statistics found good reliability. There was no statistically significant difference between the two agreement values. Category-wise agreement was excellent for normal trochlea (OBC 1) and moderate to good for severe dysplasia (OBC 4). Reliability was low moderate to poor for mild (OBC 2) or moderate (OBC 3) dysplasia. Intra-observer reliability was good to excellent (mean kappa = 0.73). Conclusion: The OBC is reliable in categorizing a normal or severely dysplastic trochlear in skeletally immature children although it fails to adequately differentiate between mild and moderate dysplasia. [ABSTRACT FROM AUTHOR]

Understanding all the technical features and functions associated with medial patellar ligament reconstruction (MPFL) with autograft will make restoration more effectual, limiting complications associated with its non-anatomical placement. We describe in this study the cases of two girls aged seven and thirteen who underwent successful MPFL reconstruction after failed proximal and distal patellofemoral realignment surgeries they had previously undergone to treat recurrent patellar dislocation. The modified Cincinnati and Kujala score were used for the preoperative and postoperative clinical evaluation of the two girls. In the final reassessment of the two girls, seven years post-operatively for the seven-year-old girl, and three years post-operatively for the thirteen-year-old girl, the modified Cincinnati score and the Kujala score were increased significantly. The restoration of the MPFL is a justified surgical method for an effective outcome of the reestablishment of patellar stability in skeletally immature patients who underwent less successful surgeries in the past. [ABSTRACT FROM AUTHOR]

Background: There has been recent debate regarding the optimal surgical management strategy for recurrent patellofemoral instability in the presence of an increased tibial tuberosity–trochlear groove (TT-TG) distance. In particular, performing a combined tibial tuberosity osteotomy (TTO) and medial patellofemoral ligament reconstruction (MPFLR) for patients with a TT-TG >20 mm has been questioned, with the hypothesis that an isolated MPFLR (iMPFLR) would be just as effective. Purpose: To pool and compare outcomes after MPFLR+TTO versus iMPFLR in patients with a TT-TG >20 mm. Study Design: Systematic review; Level of evidence, 4. Methods: PubMed-MEDLINE, Embase, Web of Science, and Cochrane Central were searched, and a systematic review was performed. Included were studies that reported postoperative redislocation rates and/or functional outcome scores for patients with recurrent patellar instability and a TT-TG >20 mm who underwent either MPFLR+TTO or iMPFLR and had minimum 2-year follow-up data. Methodologic quality was assessed using the modified Coleman Methodology Score (mCMS). A proportional meta-analysis comparing redislocation, subjective instability, and total complication rates was performed, and mean postoperative functional outcome scores were pooled using a random-effects model with a restricted maximum likelihood estimator. Results: In total, 1548 studies were screened, from which 13 were included for analysis. Of the 386 included patients (406 knees), 276 underwent MPFLR+TTO and 110 underwent iMPFLR. The mean mCMS was 61.3 ± 10.5 (range, 48-77). The pooled postoperative redislocation rate was 1.22% (95% CI, 0.22%-7%), with no significant difference between the study groups (P =.9995). The pooled complication rate was 10.17% (95% CI, 6.2%-16.3%) with no difference between groups (P =.9275), although the MPFLR+TTO group had higher heterogeneity in complication rates (I 2 = 79.4%) compared with iMPFLR (I 2 = 0%). There was no group difference in the pooled postoperative Lysholm scores (P =.5177), but patients who underwent iMPFLR had significantly higher postoperative Kujala scores compared with those who underwent MPFLR+TTO (P =.0283). Conclusion: Even in the presence of previously indicative anatomic factors (TT-TG >20 mm), TTO combined with MPFLR does not seem to confer additional benefit compared with iMPFLR. This finding could be advantageous in minimizing the burden of additional surgery with its associated risks. The study findings should, however, be interpreted with caution given the heterogeneity of the studies. [ABSTRACT FROM AUTHOR]

Background: The tibial tuberosity–trochlear groove (TTTG) distance is used to assess patellofemoral instability (PFI) and the likelihood of the development of patellofemoral disorders. The current gold standard in the assessment of the TTTG is computed tomography (CT) or magnetic resonance imaging (MRI). The current image software used for viewing these CT images does not allow for easy assessment of the TTTG. Aims: This study presents a simple method to measure the TTTG on any image software, utilizing easily available and affordable stationary. Methods: Four consecutive patients with no known knee pathologies were selected from recent studies at our institution. Their TTTGs were measured using this study's method and validated using the standard, freely available image analysis software Fiji. Pre-defined anatomical landmarks were located and marked using adhesive pieces of paper. The TTTG was defined as the distance between parallel lines through the apex of the tibial tuberosity and trough of the trochlear groove, where each of these lines is perpendicular to the Dorsal Condylar Line. Results: The TTTG measured using this study's method was found to be in agreement with the measurements made using Fiji software. Conclusions: This study demonstrates that the TTTG can be simply and quickly assessed using readily available and affordable stationery, without the need for expensive or complex secondary analysis software. This could allow for the assessment of PFI in the outpatient clinic whilst the patient is present, offering valuable assistance to the orthopaedic surgeon in clinical decision making. [ABSTRACT FROM AUTHOR]

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