Modified Elmslie-Trillat procedure for instability of the patella.

The purpose of this study was to determine whether or not the modified medial transfer of the ligamentum patellae in case of objective instability of the patella is an adequate therapy and if it is possible to improve the patellar congruence angle by this method. Between October 1987 and April 1993, 41 operations were performed in 37 patients with medialization of the medial third of the ligamentum patellae with the corresponding part of the tibial tubercule. Four patients needed a bilateral operation; the two interventions were not performed at the same time. Thirty-six operated knees (88%) were examined at a median clinical and radiological follow-up of 62.8 months (+/- 15.8 SD). For evaluation, the objective and subjective Turba score was used, and pre- and postoperative X-rays were compared. The patients' average age at the time of intervention was 23.2 years (+/- 7 years SD). The operation was performed 39 times for recurrent dislocation or subluxation, for patella alta with cartilage tissue damage, and for first time traumatic dislocation. The only postoperative complication was a temporary peroneal paresis. There were no redislocations seen at the follow-up. One patient with repeated subluxations underwent an additional lateral release combined with a repair of the medial retinaculum. In all other cases, the Turba score showed good or excellent results (subjective 1.9; objective 0.8), the patellar congruence angle was significantly improved (P < 0.001), and there were no medial subluxations. We conclude that the transfer of the medial third of the ligamentum patellae for objective instability of the patella is a minimally invasive and adequate technique to improve significantly a pathological patellar congruence angle.