Effect of Cartilage Injuries on Medial Patellofemoral Ligament Reconstruction Outcomes at Midterm Follow-up

Patellofemoral instability most commonly affects young patients and is often associated with concomitant chondral injury, the incidence of which increases with each dislocation event. The impact of these chondral injuries on the function and pain levels of patients who undergo isolated medial patellofemoral ligament (MPFL) reconstruction without bony realignment remains unclear.

The purpose of this study was to compare patient-reported outcome measures (PROMs) between individuals who underwent isolated MPFL reconstruction with concomitant cartilage restoration versus those patients who did not require a concomitant cartilage procedure at the time of their MPFL reconstruction. It was hypothesized that cartilage injury that required intervention in patients with patellofemoral instability would be associated with worse preoperative PROMs compared with patients without chondral injury and that these differences would be mitigated by concomitant surgical intervention to address chondral damage performed in addition to their MPFL reconstruction.

Cohort study; Level of evidence, 3.

Patients with recurrent patellar instability were collected in an institutional registry beginning March 2014. All patients underwent primary, unilateral, isolated MPFL reconstruction regardless of their bony anatomic features. PROMs, episodes of recurrent instability, and return to sport (RTS) data were obtained at baseline and annually. Patients were retrospectively assigned to the cartilage intervention group if they underwent concomitant particulated juvenile cartilage allograft, osteochondral allograft, open reduction internal fixation, microfracture, or removal of loose body. Those without intervention or isolated chondroplasty comprised the comparison group. PROMs were assessed at baseline and at 2 and 5 years after surgical intervention.

A total of 138 patients underwent MPFL reconstruction without bony correction between March 2014 and December 2019. Two patients were excluded for concomitant anterior cruciate ligament reconstruction. A total of 22 patients underwent concomitant cartilage restoration, whereas 114 patients underwent chondroplasty or no concomitant cartilage intervention. In total, 50 patients were evaluated at ≥5 years, of whom 40 (80%) completed follow-up PROMs. A total of 119 patients were evaluated at ≥2 years, of whom 89 (75%) completed follow-up PROMs. All PROMs improved significantly over time except for the Pediatric Functional Activity Brief Scale (Pedi-FABS) (P = .095). Baseline PROMs were significantly lower for the concomitant cartilage injury group compared with the MPFL-only group for Knee injury and Osteoarthritis Outcome Score (KOOS) Quality of Life subscale (P = .0075), KOOS Pain Score (PS) (P = .0138), and Kujala score (P = .0481). However, at 2 years after surgery, no statistically significant difference in PROMs was found between the cartilage and no-cartilage intervention groups, a finding that was maintained at 5 years after surgery. Patients in the cartilage intervention group displayed a lower overall RTS than patients in the no-intervention group (64.29% vs 92.41%; P = .0103). The patients who achieved RTS had a shorter time to RTS after cartilage intervention compared with no intervention (7.55 vs 9.46 months; P = .0461).

The treatment of cartilage lesions in addition to MPFL reconstruction for recurrent patellar instability was associated with similar improvement in PROMs compared with isolated MPFL reconstruction without cartilage intervention at 2 and 5 years after surgery, despite lower preoperative PROMs in the group requiring cartilage intervention. Patients who underwent cartilage intervention had lower overall RTS rates. Future work will seek to confirm the durability of these results with longer term follow-up.