Summary

Following MPFL reconstruction, approximately 42% of patients RTS at lower activity levels compared to pre-injury level, especially in older patients and patients who undergo concomitant TTO. Many patients do not RTS due to fear of re-injury, knee dysfunction or other life factors not related to the successful result of their MPFL reconstruction.

Abstract

Introduction

The purpose of this study is to examine the ability of patients to return to sport (RTS), their activity levels and determine reasons patients do not resume preoperative activities following medial patellofemoral ligament (MPFL) reconstruction surgery.

Methods

A retrospective chart review was performed to identify patients who underwent primary MPFL reconstruction by one of three surgeons. The following information was extracted from each chart: age at surgery, gender, surgery-side, concomitant procedures, graft tendon type and graft processing method. At a minimum one year follow-up, patients were contacted to complete a survey that included preoperative and postoperative SF-12 Physical (SF-12 P) and Mental (SF-12 M), Norwich Patellar Instability (NPI) and Tegner activity level. Student’s t-tests and multivariate analyses were used to determine predictors of worse patient-reported outcomes at time of follow-up.

Results

Thirty-eight patients (44 knees) completed the survey (71.1% female). Mean follow-up was 3.3 ± 2.0 years. Mean age at surgery was 23.3 ± 7.6 years. Significant improvements were achieved in the mean NPI score, the mean SF-12 M score (p<0.0001) and the mean SF-12 P score (p=0.03). The preoperative Tegner significantly increased from 2.3 ± 2.0 to 5.7 ± 2.4 postoperatively (p<0.0001), however, the postoperative Tegner score was significantly lower than pre-injury (7.1 ± 2.1; p=0.005). Of the 41 knees (93.2%) who played a sport, 17 knees (41.5%) did RTS and had significantly better postoperative Tegner scores (p=0.008) compared to the 24 knees (58.5%) who did not RTS. Reasons for not RTS (n=43) included: fear of re-injury (16 knees; 37.2%), knee dysfunction (10 knees; 23.3%), other life factors (10 knees; 23.3%) and lack of interest (7 knees; 16.3%). As a result, 13 knees (54.2%) changed their primary sport/activity. In multivariate analysis, for every year increase in age, the mean improvement in Tegner score decreased significantly (p=0.03). Knees (n=32) without tibial tubercle osteotomy (TTO) had significantly better postoperative Tegner scores (p=0.03) compared to knees with TTO (n=12). No associations were found between graft processing method, graft type, and any outcome score. There were no recurrent dislocations, 2 (4.5%) subjective sensation of subluxation (MPFL intact on MRI) and 1 (2.3%) patellar subluxation during examination under anesthesia requiring MPFL repair at 2.3 years postoperatively. Two (4.5%) knees required injections for DJD. Overall, 8 (18.2%) knees had any subsequent procedure, including: 1 (2.3%) knee arthroscopy for symptomatic plica, 1 (2.3%) repair for proximal pole patella fracture, 1 (2.3%) open autogenous bone grafting for nonunion after TTO, 1 (2.3%) TTO, and 4 (9.1%) hardware removals after TTO. Of these, one patient also had the above mentioned (2.3%) subsequent MPFL repair and ultimately, (2.3%) patellofemoral arthroplasty.

Conclusion

Following MPFL reconstruction, approximately 42% of patients RTS at lower activity levels compared to pre-injury level, especially in older patients and patients who undergo concomitant TTO. Subjective outcomes of MPFL reconstruction are not influenced by graft type or processing method. Many patients do not RTS due to fear of re-injury, knee dysfunction or other life factors not related to the successful result of their MPFL reconstruction.