[Retro-trochlear wedge reduction trochleoplasty for the treatment of painful patella syndrome with protruding trochleae. Technical note and early results].

PURPOSE OF THE STUDY: Patients with painful patella syndrome without objective instability are often treated by section of the lateral retinacular of the patella or advancement osteotomy of the tibial tuberosity with less than satisfactory mid-term results. One explanation of the persistent pain could be hyperpression within the femoro-patellar joint due to excessive protrusion of the trochleae (>=7 mm). We propose retro-trochlear wedge resection to achieve reduction trochleoplasty. The wedge is cut with a superior base so the trochlear angle remains unchanged. We describe here the operative technique and report early results at more than two years follow-up. MATERIAL AND
METHOD: We reviewed retrospectively 12 knees treated with trochleoplasty for painful patella syndrome. Eleven of these knees had had previous operations for objective (n=9) or potential (n=2) patellar instability. Mean follow-up was 4 years (range 2-6). A complete pre- and postoperative radiological work-up was obtained for all knees including 30 degrees flexion femoropatellar views and computed tomography measurements of TA-GT value at 30 degrees flexion. Functional outcome was studied with the Arpege scale. Trochleoplasty was performed via an anterolateral approach and was associated with frontal translation of the tibial tuberosity if the preoperative TA-GT was not in accord with the trochlear angle.
RESULTS: Functional outcome improved during the first two postoperative years then stabilized. Improvement in pain and instability was statistically significant. Functional outcome was scored good or very good for nine knees. The two failures occurred in the oldest patients whose knees had had several operations. Mean trochlear protrusion was 8 mm preoperatively and 3 mm postoperatively. All trochleoplasties healed; there was no trochlear necrosis. DISCUSSION: The described trochleoplasty has an advantage over classical reduction trochleoplasty because it does not modify the trochlear angle. In addition, it is quantifiable. It is biomechanically more logical than advancement of the tibial tuberosity. In our patients, the trochlear protuberance was reduced to 3 mm. Associated with correction of mechanical femoro-patellar anomalies in the frontal plane, this trochleoplasty can provide good relief even in patients with persistent pain in previously operated knees treated for objective or potential patellar instability or for simple patellar pain.