Adolescent patellofemoral pain: implicating the medial patellofemoral ligament as the main pain generator

Abstract

Purpose: The purpose of this study is to define the clinical presentation of adolescent patellofemoral pain.

Methods: A review was completed of all patients with patellofemoral pain at a children's hospital sports clinic over a 3-year period.

Results: One hundred and one patients (91 female) with 136 symptomatic knees were identified. Mean age was 14.4 years. Knee pain was localized to the anteromedial or anterior region of the knee in 96% of patients and was typically produced with running (94%), jumping (92%) and stair use (69%). On physical examination there was usually a non antalgic gait (99%), no patellofemoral crepitation (98%), normal lower extremity angular (84%) and rotational alignment (94%), with no foot malalignment (>97%). The medial patellofemoral ligament (MPFL) was the most palpably tender area of the knee in 98% of patients. During "lateral apprehension" testing, 89% had pain at the MPFL, but not true apprehension. A "J-sign" was present at terminal knee extension in 65%. Mean Q-angle was 18.7 degrees . Means of all radiographic measures were within normal ranges.

Conclusion: The prototypical patient had anterior/anteromedial knee pain of insidious onset during running and jumping. The most consistent physical findings were focal tenderness at the MPFL, positive terminal J-sign, and an elevated Q-angle. Most patients required only nonsurgical treatments, but 18% underwent surgical interventions for persistent pain.

Fig. 1

Drawing of the medial patellar restraints. The MPFL is usually localized at the mid-point of the patella and can be traced to the medial epicondyle