Background: No studies exist about the long-term correlation of patellofemoral osteoarthrosis to poor outcome after traditional realignment surgery for chronic patellofemoral instability. The objective of this study was to evaluate the recurrent instability and symptomatic osteoarthrosis over a long follow-up period.

Methods: Fifty-two patients underwent distal realignment surgery for chronic patellar instability, 28 with Roux-Goldthwait procedure and 24 with Krogius procedure. A follow-up evaluation was performed at a mean 12 years (range, 8 to 22 years) after surgery, in which 39 of 52 patients participated. Recurrent instability and osteoarthrotic characteristics were evaluated by plain radiographs and magnetic resonance images obtained at follow-up. The original hospital data were reviewed to assess patients’ background. Subjective symptoms were assessed with patellofemoral scores.

Results: Of the 39 controlled patients, 10 had chronic patellar instability, including 4 patients who underwent reoperation during follow-up. The mean patient age at follow-up was 33 years (range, 26 to 43). Patellofemoral full-thickness cartilage lesions were found on MRI in 29 (75%) of patients and all of the patients had mild lesions. A joint space narrowing was present in 6 cases in plain radiographs indicating severe patellofemoral osteoarthrosis. Only 48% of the patients reported satisfaction with the patellar stability and anterior knee symptoms and the unsatisfactory result was associated with patellofemoral osteoarthrosis (P=0.05). The mean Kujala score was 83 (range 52–100) points. The surgical technique employed did not affect the overall outcome.

Conclusion: The long-term outcome of traditional realignment surgery for chronic patellofemoral instability seemed to be strongly associated with patellofemoral osteoarthrosis. Despite the relatively rare occurrence of recurrent instability, less than half of patients achieved a satisfactory result. Patellofemoral osteoarthrosis seems to be the long-term consequence in patients treated with traditional surgical procedures for patellar instability. In future studies focusing on patellar stability, preventive methods against the development of patellofemoral osteoarthrosis should be emphasized.