Stein, Beth E. Shubin

Objectives: Current standard of care after a First-Time patellar instability event is non-operative management, with exceptions for patients with osteochondral fracture or loose body requiring immediate surgical intervention, patients with significant pathoanatomy, or contralateral patellar instability. For recurrent patellar instability, there is controversy as to when isolated medial patellofemoral ligament reconstruction (MPFL-R) is enough. The purpose of this study is to determine (1) the comparative outcomes of isolated MPFL-R after first-time patellar instability (FTPI) and recurrent patellar instability (RPI) and (2) the impact of osteochondral injury on outcomes after surgical treatment of FTPI. Methods: A prospective, multicenter cohort study (JUPITER: Justifying Patellar Instability Treatment by Results) database was queried for patients who underwent patellar stabilization surgery (PSS) between December 2016 and September 2022. Patients were included if they underwent a medial patellofemoral ligament reconstruction (MPFL-R) for FTPI or RPI. Those with less than 2 years of clinical follow-up, revision PSS, or concomitant bony procedures at the time of MPFL-R were excluded. Independent t-tests were performed to compare means for continuous variables, and chi-squared tests were performed to compare frequency for categorical variables, between groups. Results: A total of 739 patients met inclusion criteria with a mean age of 15.6 ± 3.3 years, and 59.9% female sex. FTPI occurred in 216 (27.2%) patients, and of these 104 (48.1%) sustained an operative chondral or osteochondral lesion. Those with FTPI had a significantly greater trochlear depth (2.9 mm vs. 2.6 mm; P = .048), but a significantly lower rate of pathological trochlear bump > 5 mm (52.3% vs. 67.8%; P = .008) than those with RPI (Table 1). Among the FTPI cohort, those with treatment of a chondral lesion were less likely to have patella alta (Caton-Deschamps Index > 1.3) (14.9% vs. 41.3%, P = .006), and less frequently had a mild or severe J-sign (25.0% vs. 42.7%, p = .016) than those without a chondral intervention (Table 2). Postoperatively, there were no differences with rates of recurrent instability (8.3% vs. 12.3%; P = .130) or return to sport (90.4% vs. 94.5%; P = .182) between FTPI and RPI, respectively (Table 3). There were no differences with rates of recurrent instability (7.6% vs. 9.1%; P = .807) or return to sport (89.1% vs. 91.7%; P = .755) between those with or without a chondral intervention, respectively (Table 4). Conclusions: This study demonstrates no difference in rates of recurrent post-operative instability between FTPI and RPI with rates consistent with the current literature. MPFL reconstruction remains as a durable surgical treatment option for patients presenting with either FTPI or RPI with relatively low rates of recurrent instability. In this patient population, patella alta was found to be protective of osteochondral injury which is also consistent with existing literature. Continued, long-term investigation is needed to understand outcomes for First-Time patellar instability and to better define the indications for surgical interventions in this population.

Background: Particulated juvenile articular cartilage (PJAC) implantation has demonstrated promising early results in the treatment of symptomatic articular cartilage defects of the patella. However, some uncertainty exists regarding the stability of this cell-based technique in lesions that are not well contained or shouldered. Purpose: To compare clinical and magnetic resonance imaging (MRI) outcomes of PJAC treatment in shouldered versus unshouldered full-thickness cartilage defects of the patella. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective review of prospectively collected data from an institutional knee registry was conducted to identify patients treated with PJAC for full-thickness symptomatic patellar cartilage lesion between January 2009 and August 2017. Cartilage defects were graded arthroscopically according to the Outerbridge classification and characterized as shouldered or unshouldered. For the primary outcome, postoperative MRI studies were read by a musculoskeletal fellowship-trained radiologist who characterized the percentage of fill based on both coronal and sagittal images. Patient-reported outcome measures (PROMs) were obtained at baseline and 2-year follow-up. MRI and PROM results were compared between the shouldered and unshouldered cohorts. Results: A total of 64 knees in 60 patients (mean age, 26.3 ± 7.6 years) were identified, of which 62 (97%) knees underwent a concomitant patellar stabilization or offloading procedure. There were 32 (50%) shouldered and 32 (50%) unshouldered defects. On postoperative MRI, 68.8% of shouldered lesions demonstrated 67% to 100% fill, compared with 59.4% of unshouldered lesions; 12.5% of shouldered lesions and 15.6% of unshouldered lesions demonstrated 34% to 66% fill; and 18.8% of shouldered lesions and 25.0% of unshouldered lesions demonstrated 0% to 33% fill ( P = .604). At 2 years, significant improvements were observed in Knee Injury and Osteoarthritis Outcome Score (KOOS) Quality of Life (QOL) (23.1 to 65.3; P < .001), International Knee Documentation Committee (IKDC) (41.2 to 76.0; P < .001), KOOS Physical Function Shortform (PS) (34.8 to 13.9; P < .001), Kujala (52.0 to 87.5; P < .001), 12-Item Short Form Survey (SF-12) Physical Health (39.5 to 51.5; P < .001), Veterans Rand 12 Item Health Survey (VR-12) Physical Health (40.7 to 52.8; P < .001), Veterans Rand 6D (0.66 to 0.79; P < .001), SF-12 Mental Health (48.9 to 53.4; P = .015), and VR-12 Mental Health (49.4 to 54.0; P = .019) values. No significant change was observed in Pediatric Functional Activity Brief Scale score (9.1 to 10.3; P = .384). All PROMs were equivalent between shouldered and unshouldered defects at the 2-year follow-up ( P = .318-.980). There was a greater improvement in both KOOS PS (27.2 vs 10.7; P = .015) and Kujala (44.3 vs 26.9; P = .039) values from baseline to the 2-year follow-up in the shouldered group. Conclusion: PJAC implantation with concomitant patellar stabilization led to significantly improved PROMs for both shouldered and unshouldered patellar cartilage lesions over time. Additionally, minimal differences were observed between shouldered and unshouldered defects treated with PJAC at the 2-year follow-up.