Diduch, David R.

Background: Acute traumatic patellar dislocations may cause intra-articular derangements of the knee in the setting of acute and chronic instability which may not always be appropriately identified on magnetic resonance imaging (MRI). Purpose: To determine the rates of coexisting intra-articular pathology in patients with patellar instability requiring medial patellofemoral ligament (MPFL) reconstruction and to report discrepancies between preoperative magnetic resonance imaging (MRI) findings and diagnostic arthroscopy results. Study Design: Cohort study (Diagnosis); Level of evidence, 3. Methods: Patients who underwent MPFL reconstruction at a single institution between 2010 and 2023 were identified. Operative reports and preoperative MRIs were reviewed. Records without full MRI reports as read by a radiologist or cases in which a diagnostic arthroscopy was not conducted were excluded. Intra-articular pathologies noted on MRI and confirmed by arthroscopy were documented. MRI findings were considered to be discordant from arthroscopic findings if a lesion was identified on diagnostic arthroscopy that was not present in the full MRI report and that lesion resulted in additional surgical procedures. Results: There were 331 arthroscopic procedures conducted within the study population of 508 patients who underwent diagnostic arthroscopy at the time of their patellar stabilization procedures. These procedures included 180 loose body removals, 95 osteochondral lesions treated via a variety of interventions including open reduction and internal fixation (26 cases), particulated allograft chondral grafting (30 cases), osteochondral allograft transplantation (9 cases), and microfracture (30 cases), and 39 meniscal tears resulting in 33 partial meniscectomies and 6 meniscal repairs. Among these 508 patients, 105 (21%) demonstrated discordance of preoperative MRI and arthroscopic findings that necessitated additional procedures. This discordance was responsible for a total of 109 (33%) of the 331 arthroscopic procedures. These included 75 loose body removals, 2 osteochondral fracture fixation procedures, 2 microfractures for full-thickness cartilage loss, 16 partial meniscectomies, and 2 meniscal repairs, among others. Conclusion: Among patients undergoing patellar stabilization, 21% had intra-articular lesions not identified on preoperative MRI detected at the time of diagnostic arthroscopy that resulted in surgical intervention. This study, representing the largest cohort to date of patellar stabilization surgeries with both MRI and arthroscopy findings, underscores the importance of diagnostic arthroscopy for improving diagnostic accuracy and addressing associated intra-articular pathology.

Background: In skeletally immature patients, alternative surgical approaches should be undertaken for the treatment of patellofemoral instability that respect the open physis. Remaining growth can be exploited for correction of genu valgum, a known anatomic risk factor of patellofemoral instability. Indications: A skeletally immature 14-year-old boy with bilateral genu valgum and patella alta presented with symptomatic, recurrent left knee patellar instability precluding sports participation and causing dysfunction in his activities of daily living. Technique Description: A midline approach to the knee was used. Medial patellofemoral ligament reconstruction (MPFL-R) was completed up until the point of femoral-sided allograft fixation. The socket for femoral-sided graft fixation was reamed with an all-epiphyseal technique. Next, growth modulation with temporary hemiepiphysiodesis of the medial distal femoral physis was undertaken with an 8-plate bilaterally. Patellar tendon shortening was completed. Femoral-sided graft fixation for the MPFL-R was then completed. Results: There were no acute complications associated with surgery. Surgical management led to resolution of the patient’s patellar instability. The patient is being followed for timing of hemiepiphysiodesis plate removal. Discussion/Conclusion: In skeletally immature patients, a physeal-sparing MPFL-R is a viable treatment option to address recurrent patellar instability. Other anatomic risk factors, such as genu valgum and patella alta, may be concomitantly addressed using techniques that are respective of the open physis. 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.

Objectives: While uncommon, acute traumatic patellar dislocations can lead to recurrent symptoms of patellar instability in 15% to 45% of patients. Patellar stability is an interplay of bony and soft tissue restraints as well as anatomic factors, however, a mainstay of treatment remains reconstruction of the medial patellofemoral ligament (MPFL). Instability events can lead to intra-articular derangements of the knee, both in the acute and chronic patellar instability setting. These findings may not always be appropriately identified on magnetic resonance imaging (MRI). The incidence of these “surprise” injuries have not been previously reported. The purpose of this study is to determine the rates of coexisting intra-articular pathology in patients with patellar instability requiring MPFL reconstruction and elucidate any discordance between preoperative MRI findings and diagnostic arthroscopy findings. Methods: All patients undergoing MPFL reconstruction at a single institution between 2010 and 2023 were identified and preoperative MRI reports, defined as the most recent MRI report to the date of surgery with no interval traumatic events, were queried. Records without full MRI reports as read by a radiologist or cases in which a diagnostic arthroscopy was not conducted were excluded. MRI findings were discordant from arthroscopic findings if a lesion identified on diagnostic arthroscopy was not present in the full MRI report. Procedures that were undertaken because of these missed pathologies on MRI were recorded. Results: A total of 640 patients were identified during the study period, and 507 complete records were ultimately included. Preoperative MRI identified patellar osteochondral lesions or cartilage fissures in 333 patients (66%), loose bodies in 119 patients (24%), lateral femoral condyle osteochondral lesions or fissures in 97 patients (19%) and meniscus tears in 47 patients (9%). Among these patients, 172 (34%) had a diagnosis at the time of arthroscopy which was not identified on the preoperative MRI. These arthroscopic findings resulted in 75 loose body removals, 74 patellar shaving chondroplasties, 16 partial meniscectomies, 3 microfractures, 3 osteochondral lesion open reduction internal fixation, and 2 meniscal repairs which would have been missed without diagnostic arthroscopy due to discordant MRI findings. Conclusions: Over one-third of patients at a single institution who underwent diagnostic arthroscopy in the setting of patellar instability surgery had pathology identified which required surgical intervention that was not reported on a preoperative MRI. A comparison of MRI and diagnostic arthroscopy has been extensively reported on for other knee pathologies including ACL tear and lateral meniscal tear; however, there has been no similar investigation of the reliability of MRI for identification of concomitant pathology in the setting of patellar instability to date. The findings of this study highlight the importance of diagnostic arthroscopy in the treatment of patellar instability, the frequency with which this altered treatment, and the high preponderance of discordant MRI findings.

Abstract Osteochondritis dissecans of the elbow is a rare but debilitating pathology typically found in the adolescent repetitive overhead athlete. In the setting of unstable lesions, mechanical symptoms, or deteriorating function despite appropriate conservative management, surgical osteochondral allograft transplantation of the capitellum is a viable option for even large lesions (>10 mm), with minimal morbidity and good return of function. We describe a technique for performing a large osteochondral allograft transplantation of the capitellum. Technique Video video See video under supplementary data.