Methods

Seventeen consecutive patients (19 knees) with patellar instability secondary to trochlear dysplasia underwent trochleoplasty, of which 12 knees (12 patients) were radiologically evaluated pre- and post surgery using axial CT and MRI imaging. Their mean age at time of surgery was 28.1 years (15 to 44). The mean follow-up was 2.2 years (0.5 to 5). The following four radiological outcomes were used: trochlear depth (TD), transverse patellar shift (TPS), lateral patellar inclination angle (LPIA) and sulcus angle (SA). All knees were assessed post-operatively using MRI. The axial CT images were reformatted which allowed for direct comparison with MRI. Each knee was radiologically evaluated twice by a senior musculoskeletal radiology consultant to increase data accuracy and assess for intra-observer reliability using the intraclass correlation coefficient (ICC). Functional outcomes consisted of the KOOS, Lysholm, Kujala and Tegner scores.