Summary

This study compared patient reported outcomes in individuals with recurrent patellofemoral instability who underwent isolated medial patellofemoral ligament (MPFL) reconstruction with concomitant cartilage restoration to patients who did not require a concomitant cartilage procedure at the time of their MPFL reconstruction.

Abstract

Background

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 MPFL reconstruction without bony realignment remains unclear. The purpose of this study is to compare Patient Reported Outcome Measures (PROMs) between individuals who underwent isolated MPFL reconstruction with concomitant cartilage restoration to those patients who did not require a concomitant cartilage procedure at the time of their MPFL reconstruction. We hypothesized that cartilage injury that required intervention in patients with patellofemoral instability would result in worse preoperative PROMs compared to 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.

Methods

Patients with recurrent patellar instability were collected in an institutional registry beginning in March 2014. All patients underwent primary, unilateral, isolated MPFL reconstruction regardless of their bony anatomy. 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 (PJAC), osteochondral allograft (OCA), open reduction internal fixation (ORIF), microfracture, or removal of loose body. Those without intervention or isolated chondroplasty comprised the comparison group.  PROMs were assessed at baseline, 2 and 5 years after surgical intervention.

Results

138 patients underwent MPFL reconstruction without bony correction between March 2014 and December 2019. 22 subjects underwent concomitant cartilage restoration, while 114 subjects underwent chondroplasty or no concomitant cartilage intervention. 50 patients reached ≥ 5-years, of which 40 (80%) completed follow-up PROMs. 119 patients reached ≥2-years, of which 89 (75%) completed follow-up PROMs. All PROMs improved over time except for Pedi-FABS which had no change (P=0.095). Baseline PROMs were significantly lower for the concomitant cartilage injury group compared to the MPFL-only group for KOOS QL (p = 0.0075), KOOS PS (p = 0.0138), and Kujala scores (p = 0.0481). However, at 2 years after surgery, there was no statistically significant difference in PROMs between the cartilage and no-cartilage intervention groups which was maintained at 5 years after surgery.  Patients in the cartilage intervention group displayed a lower overall return to sport than patients in the no-intervention group (64.29% vs 92.41%; p = 0.0103), with a shorter time to RTS following cartilage intervention compared to no intervention (7.55 vs. 9.46 months; p = 0.0461).

Conclusion

The treatment of cartilage lesions in addition to MPFL reconstruction for recurrent patellar instability resulted in similar improvement in PROMs when compared to 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 rates of return to sport. Future work will seek to confirm the durability of these results with longer term follow-up.