Patellofemoral Osteoarthritis 15 Years After Anterior Cruciate Ligament Injury--a Prospective Cohort Study

Objective: Prevalence and clinical relevance of patellofemoral (PF) osteoarthritis (OA) after anterior cruciate ligament (ACL) injury.

Method: Prospectively we studied 94 out of 100 consecutive patients 15 years after acute ACL injury. ACL reconstructions were only performed late if recurrent "give way" persisted or a secondary meniscal injury suitable for repair occurred. The subjects, mean age 42 years, had knee radiographs including skyline PF view taken, which were graded according to the atlas of the Osteoarthritis Research Society International. Knee-related symptoms and function were assessed by questionnaires.

Results: PF OA was present in 12/75 knees (16%). Of 94 patients 22 (23%) have had their ACL reconstructed during follow-up. Meniscal injury and ACL reconstruction had occurred more often in knees with PF OA than in knees without PF OA (P=0.004 and P=0.002, respectively). Seven of 15 ACL reconstructed knees showed radiographic PF OA at follow-up. Knees with PF OA had more extension and flexion deficit than knees without PF OA. Subjects with PF OA maintained a higher activity level from injury to follow-up, but did not differ significantly from those without PF OA regarding patient-relevant symptoms and knee function. However, there was a trend for worse outcome in subjects with PF OA.

Conclusion: We found a relatively low prevalence of mild PF OA after ACL injury treated non-operatively, and it had limited impact on knee symptoms and patient-relevant knee function. At follow-up PF OA was associated with higher activity level, meniscal injury, extension and flexion deficit, and ACL reconstruction.