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Objective: To compare MRI features of medial and lateral patellar stabilizers in patients with and without patellar instability., Methods: Retrospective study of 196 patients (mean age, 33.1 ± 18.5 years; 119 women) after diagnosis of patellar instability (cohort-1, acute patellar dislocation; cohort-2, chronic patellar maltracking) or no patellar instability (cohort-3, acute ACL rupture; cohort-4, chronic medial meniscus tear). On MRI, four medial and four lateral stabilizers were evaluated for visibility and injury by three readers independently. Inter- and intra-reader agreement was determined., Results: Medial and lateral patellofemoral ligaments (MPFL and LPFL) were mostly or fully visualized in all cases (100%). Of the secondary patellar stabilizers, the medial patellotibial ligament was mostly or fully visualized in 166 cases (84.7%). Other secondary stabilizers were mostly or fully visualized in only a minority of cases (range, 0.5-32.1%). Injury scores for all four medial stabilizers were higher in patients with acute patellar dislocation than the other 3 cohorts (p < .05). Visibility inter- and intra-reader agreement was good for medial stabilizers (κ 0.61-0.78) and moderate-to-good for lateral stabilizers (κ 0.40-0.72). Injury inter- and intra-reader agreement was moderate-to-excellent for medial stabilizers (κ 0.43-0.90) and poor-to-moderate for lateral stabilizers (κ 0-0.50)., Conclusion: The MPFL and LPFL were well visualized on MRI while the secondary stabilizers were less frequently visualized. The secondary stabilizers were more frequently visualized medially than laterally, and patellotibial ligaments were more frequently visualized compared to the other secondary stabilizers. Injury to the medial stabilizers was more common with acute patellar dislocation than with chronic patellar maltracking or other knee injuries., (© 2023. The Author(s), under exclusive licence to International Skeletal Society (ISS).)

Aims: The aim of this study was to establish consensus statements on medial patellofemoral ligament (MPFL) reconstruction, anteromedialization tibial tubercle osteotomy, trochleoplasty, and rehabilitation and return to sporting activity in patients with patellar instability, using the modified Delphi process., Methods: This was the second part of a study dealing with these aspects of management in these patients. As in part I, a total of 60 surgeons from 11 countries contributed to the development of consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered unanimous., Results: Of 41 questions and statements on patellar instability, none achieved unanimous consensus, 19 achieved strong consensus, 15 achieved consensus, and seven did not achieve consensus., Conclusion: Most statements reached some degree of consensus, without any achieving unanimous consensus. There was no consensus on the use of anchors in MPFL reconstruction, and the order of fixation of the graft (patella first versus femur first). There was also no consensus on the indications for trochleoplasty or its effect on the viability of the cartilage after elevation of the osteochondral flap. There was also no consensus on postoperative immobilization or weightbearing, or whether paediatric patients should avoid an early return to sport., Competing Interests: S. L. Sherman reports royalties or licenses from CONMED Linvatec, consulting fees from Arthrex, BioVentus, JRF Ortho, Kinamed, Smith & Nephew, Vericel, CONMED Linvatec, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Arthex, Joint Restoration Foundation, Kinamed, Smith & Nephew, and Vericel, and stock or stock options from Epic Bio, Reparel, Sarcio, and Vivorte, all of which are unrelated to this study. J. Chahla reports consulting fees from Arthrex, CONMED Linvatec, Ossur, and Smith & Nephew, and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Smith & Nephew, all of which are unrelated to this study. M. J. Alaia reports consulting fees from BodyCad, JRF Ortho, and Mitek, institutional grants from Orcosa, and royalties from Springer, all of which are unrelated to this study. M. J. Tanaka reports grants or contracts from FujiFilm, royalties or licenses from Verywell, and consulting fees from Depuy Synthes, all of which are unrelated to this study. J. L. Pace reports consulting fees from Arthrex and JRF Ortho, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Arthrex, and stock or stock options from OutcomeMD, all of which are unrelated to this study. L. M. Jazwari reports grants or contracts from Arthrex, Mitek, Smith & Nephew, and Wolters Kluwer Health, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Wolters Kluwer Health, and stock or stock options from Lazurite, all of which are unrelated to this study., (© 2023 The British Editorial Society of Bone & Joint Surgery.)

Aims: The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach., Methods: A total of 60 surgeons from 11 countries were invited to develop consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest within patellar instability. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered to be unanimous., Results: Of 27 questions and statements on patellar instability, three achieved unanimous consensus, 14 achieved strong consensus, five achieved consensus, and five did not achieve consensus., Conclusion: The statements that reached unanimous consensus were that an assessment of physeal status is critical for paediatric patients with patellar instability. There was also unanimous consensus on early mobilization and resistance training following nonoperative management once there is no apprehension. The statements that did not achieve consensus were on the importance of immobilization of the knee, the use of orthobiologics in nonoperative management, the indications for MPFC repair, and whether a vastus medialis oblique advancement should be performed., Competing Interests: D. Dejour reports royalties or licenses from Corin, Arthrex, and SBM and consulting fees from Smith & Nephew, all unrelated to this study. M. K. Mulcahey reports consulting fees from Arthrex, unrelated to this study. J. R. Wittstein reports consulting fees from Geistlich, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Arthrex and Vericel, stock or stock options from ViewFi Health, all unrelated to this study. L. M. Jazwari reports grants or contracts from Arthrex, Mitek, Smith & Nephew, and Wolters Kluwer Health, both related and unrelated to this study, royalties or licenses and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Wolters Kluwer Health, and stock or stock options from Lazurite, all unrelated to this study., (© 2023 The British Editorial Society of Bone & Joint Surgery.)

Patellofemoral pain and instability are common indications for imaging that are encountered in everyday practice. The authors comprehensively review key aspects of patellofemoral instability pertinent to radiologists that can be seen before the onset of osteoarthritis, highlighting the anatomy, clinical evaluation, diagnostic imaging, and treatment. Regarding the anatomy, the medial patellofemoral ligament (MPFL) is the primary static soft-tissue restraint to lateral patellar displacement and is commonly reconstructed surgically in patients with MPFL dysfunction and patellar instability. Osteoarticular abnormalities that predispose individuals to patellar instability include patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Clinically, patients with patellar instability may be divided into two broad groups with imaging findings that sometimes overlap: patients with a history of overt patellar instability after a traumatic event (eg, dislocation, subluxation) and patients without such a history. In terms of imaging, radiography is generally the initial examination of choice, and MRI is the most common cross-sectional examination performed preoperatively. For all imaging techniques, there has been a proliferation of published radiologic measurement methods. The authors summarize the most common validated measurements for patellar malalignment, trochlear dysplasia, and tibial tubercle lateralization. Given that static imaging is inherently limited in the evaluation of patellar motion, dynamic imaging with US, CT, or MRI may be requested by some surgeons. The primary treatment strategy for patellofemoral pain is conservative. Surgical treatment options include MPFL reconstruction with or without osseous corrections such as trochleoplasty and tibial tubercle osteotomy. Postoperative complications evaluated at imaging include patellar fracture, graft failure, graft malposition, and medial patellar subluxation. © RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Patellar instability is one of the most prevalent knee disorders, with dislocations occurring in 5 to 43 cases per 10,000 annually. Traumatic patellar dislocation can result in significant morbidity and is associated with patellofemoral chondral injuries and fractures, medial soft tissue disruption, pain, and reduced function, and can lead to patellofemoral osteoarthritis. Chronic and recurrent instability can lead to deformation and incompetence of the medial soft tissue stabilizers. Despite recent gains in understanding the pathoanatomy of this disorder, the management of patients with this condition is complex and remains enigmatic., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Background: The relationship between the medial patellofemoral ligament (MPFL) and the distal femoral physis has been reported in multiple studies., Purpose: To determine the distance from the MPFL central origin on the distal femur to the medial distal femoral physis in skeletally immature participants., Study Design: Systematic review., Methods: A systematic review was performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Multiple databases were searched for studies investigating the anatomic origin of the MPFL on the distal femur and its relationship to the medial distal femoral physis in skeletally immature participants. Study methodological quality was analyzed with the Anatomical Quality Assessment tool, with studies categorized as low risk, high risk, or unclear risk of bias. Continuous variable data were reported as mean ± SD. Categorical variable data were reported as frequency with percentage., Results: Seven articles were analyzed (298 femurs, 53.7% male patients; mean age, 11.7 ± 3.4 years). There was low risk of bias based on the Anatomical Quality Assessment tool. The distance from the MPFL origin to the distal femoral physis ranged from 3.7 mm proximal to the physis to 10.0 mm distal to the physis in individual studies. Six of 7 studies reported that the MPFL origin on the distal femur lies distal to the medial distal femoral physis in the majority of specimens. The MPFL originated distal to the medial distal femoral physis in 92.8% of participants at a mean distance of 6.9 ± 2.4 mm., Conclusion: The medial patellofemoral ligament originates distal to the medial distal femoral physis in the majority of cases at a mean proximal-to-distal distance of 7 mm distal to the physis. However, this is variable in the literature owing to study design and patient age and sex.

Chondral lesions of the patellofemoral joint are common, and when symptomatic they can be difficult to manage. Not only are there various degrees of injury with multiple etiologies, but patellofemoral anatomy is complex and the patient's lower extremity alignment may contribute to the pathology. Treatment depends on the location, size, and depth of the lesion and may require realignment or concomitant stabilizing procedures. Tibial tubercle osteotomy can be performed in isolation or combined with various cartilage-based treatments, including marrow stimulation techniques, autologous chondrocyte implantation, osteochondral autograft, and osteochondral allograft. End-stage lesions, failed primary patellofemoral cartilage restoration with diffuse involvement, or isolated primary patellofemoral arthritis may be amenable to treatment with patellofemoral arthroplasty. Recent investigations in properly indicated patients using advanced techniques have shown that management of patellofemoral cartilage disease is now more effective and predictable than in the past.

Patellofemoral instability is a common pathology especially in the adolescent female population. 1 , 2 Based on this, the provider needs to consider these risk factors and the possibility of initial surgical management in these patient populations following a first-time patellar dislocation. Surgical options for management of patellar instability and cartilaginous injury include medial patellofemoral ligament repair, medial patellofemoral ligament reconstruction, tibial tubercle osteotomy, and various cartilaginous repair/restoration procedures. It is important to be knowledgeable about the clinical and anatomic/radiographic risk factors associated with patients presenting with patellar instability, the algorithm for treatment, the indications and surgical technique for medial patellofemoral ligament reconstruction and tibial tubercle osteotomy, and management of cartilaginous injury to the patellofemoral joint.3 , 4 More recent evidence has shown patients with specific risk factors such as skeletal immaturity, an incompetent medial soft-tissue sleeve, family history of patellar dislocation, elevated tibial tubercle to trochlear groove distance, patella alta, and high-grade trochlear dysplasia experience high rates of re-dislocation after initial nonsurgical management. 4 - 9 Based on this, the provider needs to consider these risk factors and the possibility of initial surgical management in these patient populations following a first-time patellar dislocation. Surgical options for management of patellar instability and cartilaginous injury include medial patellofemoral ligament repair, medial patellofemoral ligament reconstruction, tibial tubercle osteotomy, and various cartilaginous repair/restoration procedures. It is important to be knowledgeable about the clinical and anatomic/radiographic risk factors associated with patients presenting with patellar instability, the algorithm for treatment, the indications and surgical technique for medial patellofemoral ligament reconstruction and tibial tubercle osteotomy, and management of cartilaginous injury to the patellofemoral joint.

Background: Many surgical options for treating patellofemoral (PF) cartilage lesions are available but with limited evidence comparing their results., Purpose: To determine and compare outcomes of PF cartilage restoration techniques., Study Design: Systematic review and meta-analysis., Methods: PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines were followed by utilizing the PubMed, EMBASE, and Cochrane Library databases. Inclusion criteria were clinical studies in the English language, patient-reported outcomes after PF cartilage restoration surgery, and >12 months' follow-up. Quality assessment was performed with the Coleman Methodology Score. Techniques were grouped as osteochondral allograft transplantation (OCA), osteochondral autograft transfer (OAT), chondrocyte cell-based therapy, bone marrow-based therapy, and scaffolds., Results: A total of 59 articles were included. The mean Coleman Methodology Score was 71.8. There were 1937 lesions (1077 patellar, 390 trochlear, and 172 bipolar; 298 unspecified). The frequency of the procedures was as follows, in descending order: chondrocyte cell-based therapy (65.7%), bone marrow-based therapy (17.2%), OAT (8%), OCA (6.6%), and scaffolds (2.2%). When compared with the overall pooled lesion size (3.9 cm 2 ; 95% CI, 3.5-4.3 cm 2 ), scaffold (2.2 cm 2 ; 95% CI, 1.8-2.5 cm 2 ) and OAT (1.5 cm 2 ; 95% CI, 1.1-1.9 cm 2 ) lesions were smaller ( P < .001), while chondrocyte cell-based therapy lesions were larger (4.7 cm 2 ; 95% CI, 4.1-5.3 cm 2 ; P = .039). Overall, the instability pool was 11.9%, and the anatomic risk factors pool was 32.1%. Statistically significant improvement was observed on at least 1 patient-reported outcome in chondrocyte cell-based therapy (83%), OAT (78%), OCA (71%), bone marrow-based therapy (64%), and scaffolds (50%). There were no significant differences between any group and the overall pooled change in International Knee Documentation Committee score (30.2; 95% CI, 27.4-32.9) and Lysholm score (25.2; 95% CI, 16.9-33.5). There were no significant differences between any group and the overall pooled rate in minor complication rate (7.6%; 95% CI, 4.7%-11.9%) and major complication rate (8.3%; 95% CI, 5.7%-12.0%); however, OCA had a significantly greater failure rate (22.7%; 95% CI, 14.6%-33.4%) as compared with the overall rate (6.8%; 95% CI, 4.7%-9.5%)., Conclusion: PF cartilage restoration leads to improved clinical outcomes, with low rates of minor and major complications. There was no difference among techniques; however, failures were higher with OCA.

Tibial tubercle osteotomy (TTO) is a procedure that may be used to address a wide array of patellofemoral joint pathology. The most common indications for TTO include (1) patellar instability, including either a lateralized force vector or abnormal patellar alta, and (2) patellar focal cartilage defects or chondromalacia. Customization of the TTO can effectively address the patellofemoral joint pathology by modifying patellar tracking in the trochlear groove and/or altering the contact pressures experienced by the patellofemoral cartilage. TTO may be most successful when performed in conjunction with soft-tissue stabilization and/or biological augmentation of chondral injuries. Specifically, isolated anteromedialization is recommended for focal, distal lateral patellar lesions; combined anteromedialization and cartilage restoration are recommended for medial, central, and/or panpatellar cartilage pathology; medialization with soft-tissue stabilization is recommended for a lateralized tubercle position (elevated tibial tubercle-trochlear groove distance); and distalization with soft-tissue stabilization is recommended for patella alta. Clinical studies have shown good to excellent results at long-term follow-up when a TTO is performed for patellar instability, whereas TTO performed for chondral defects has shown good to excellent outcomes that correlate strongly with the size and location of the chondral defect. With appropriate patient selection, TTO is a valuable tool for the treatment of patellofemoral joint pathology., (Copyright © 2019 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.)

Purpose: The medial patellotibial ligament (MPTL), the medial patellofemoral ligament (MPFL), and the medial patellomeniscal ligament (MPML) support the stability of the patellofemoral joint. The purpose of this systematic review was to report the surgical techniques and clinical outcomes of the repair or reconstruction of the MPTL in isolation or concomitant with the MPFL and/or other procedures., Methods: A systematic review of the literature was conducted. Inclusion criteria were articles in the English language that reported clinical outcomes of the reconstruction of the MPTL in isolation or in combination with the MPFL and/or other procedures. Included articles were then cross-referenced to find additional journal articles not found in the initial search. The methodological quality of the articles was determined using the Coleman Methodology Score., Results: Nineteen articles were included detailing the clinical outcomes of 403 knees. The surgical procedures described included hamstrings tenodesis with or without other major procedures, medial transfer of the medial patellar tendon with or without other major procedures and the reconstruction of the MPTL in association with the MPFL. Overall, good and excellent outcomes were achieved in > 75% of cohorts in most studies and redislocations were < 10%, with or without the association of the MPFL. An exception was one study that reported a high failure rate of 82%. Results were consistent across different techniques. The median CMS for the articles was 66 out of 100 (range 30-85)., Conclusion: Across different techniques, the outcomes are good with low rates of recurrence, with one article reporting a high rate of recurrence. Quality of the articles is variable, from low to high. Randomized control trials are needed for a better understanding of the indications, surgical techniques, and clinical outcomes. This systematic review suggests that the reconstruction of the MPTL leads to favorable clinical outcomes and supports the role of the procedure as a valid surgical patellar stabilization procedure., Level of Evidence: IV: systematic review of level I-IV studies.

For lateral retinaculum (LR) tightness, release or lengthening is the indicated surgical correction. LR release (LRR) or lengthening (LRL) may be a primary treatment for painful lateral compression syndrome or as an adjunct treatment in the setting of patellofemoral instability. Although it is challenging, assessment of the soft-tissue balance between the medial restraint (the medial patellofemoral ligament) and the lateral restraint (the lateral retinaculum) is fundamental to a good outcome. LRR and LRL are effective in the treatment of patellofemoral disorders in which lateral tightness is part of the pathology. Understanding the indications for treatment is essential. Although both procedures have standard postoperative complications, LRL as an alternative to LRR maintains lateral soft-tissue integrity and avoids iatrogenic medial patellar laxity, which is a serious complication with LRR. For these reasons, we recommend using LRL to address LR tightness in patellofemoral disorders., Competing Interests: Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article.

Tibial tuberosity osteotomy (TTO) is a well-described treatment option for a broad range of patellofemoral joint disorders, including patellofemoral instability, patellar and trochlear focal chondral lesions, and patellofemoral arthritis. The purpose of this article is to review the evolution of the TTO procedure, from the original Hauser procedure to the current anteromedialization procedure, as well as discuss the pertinent anatomy and radiographs that accompany this procedure. The article highlights the surgical techniques for some of the more commonly performed TTO procedures and discusses the outcomes of the various TTO techniques. Complications, as well as clinical pearls to avoid these complications, are also included., (© 2013 The Author(s).)

Patellofemoral disorders are common. There is a broad spectrum of disease, ranging from patellofemoral pain and instability to focal cartilage disease and arthritis. Regardless of the specific condition, abnormal anatomy and biomechanics are often the root cause of patellofemoral dysfunction. A thorough understanding of normal patellofemoral anatomy and biomechanics is critical for the treating physician. Recognizing and addressing abnormal anatomy will optimize patellofemoral biomechanics and may ultimately translate into clinical success., (Copyright © 2014 Elsevier Inc. All rights reserved.)