Abstract
Purpose of Study
To identify the degree of morphological change achievable following the Bereiter trochleoplasty and to establish whether these results are comparable with functional outcomes.
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.
Results
The ICC for all four radiological outcomes revealed high intra-observer reliability (0.89-0.92) suitable for clinical application. The results clearly show an increase in TD and TSP with median differences of 4mm (0.5-5) and 5.5mm (1.75-10) respectively. Decreases in SA and LPIA were observed with median differences of 14° (12.75-23) and 10.5° (7-21.75) respectively. These morphological changes resulted in improved patellar stability as exemplified by no re-dislocations and excellent functional outcomes: KOOS score 89.59 (81.97 to 93.36), Lysholm 97.5 (91.75 to 100), Kujala 93 (88.75-96.5) and Tegner Activity Scale increased from level 1 to 4 (p = 0.0002).
Conclusion
This evaluation has shown the Bereiter trochleoplasty improves the radiological appearance of trochlear dysplasia close to normal in the proximal trochlea leading to improved patellofemoral congruency and excellent functional outcomes.
