The three-in-one procedure for recurrent dislocation of the patella in skeletally immature children and adolescents

Introduction: Recurrent patellar dislocations are common injuries in children and adolescents. This prospective cohort study evaluates clinically and functionally a selected group of skeletally immature individuals patients who underwent the 3-in-1 procedure for chronic patellar instability. Materials and Methods: Twenty-five skeletally immature patients (age, 13.5 ± 3.8 years), without any anatomic predisposing factors, who were suffering from recurrent unilateral patellar dislocation were included in the study and followed until skeletal maturation. The 3-in-1 procedure is an extensor mechanism realignment of the knee combining lateral release, vastus medialis obliquus muscle advancement, and transfer of the medial third of the patellar tendon to the medial collateral ligament. The patients were regularly followed-up postoperatively at 2, 4, 8, 12, and 24 weeks, and then annually. Evaluation included the modified Cincinnati and the Kujala scores, anthropometry, plain radiography, and isokinetic dynamometry. Results: The average follow-up was 3.8 years (2.5-6). The mean modified Cincinnati score increased from 51.7 to 94.3 (P < .02), while the mean Kujala scores increased from 52.4 to 93.8 (P < .02). The muscle volume of the thigh of the operated limb increased with time, but remained significantly less well developed than the muscle volume of the thigh of the nonoperated limb (P = .03). The Insall-Salvati index remained essentially unchanged, being 1.04 preoperatively and 1.02 at latest follow-up. Significant differences were found between the operated and the contralateral limb in the various isokinetic strength variables at all angular velocities measured at the latest follow-up (.05 < P < .0042). Only 1 patient suffered a patellar redislocation. Discussion: The minimum follow-up of 2.5 years and until skeletal maturation is long enough to consider that the results of surgery had stabilized. In a prospective randomized study, Palmu et al. observed that most of the first redislocations occurred within 2 years after surgery. Side-to-side differences in isokinetic strength and in anthropometric indices persist despite subjective success of the procedure. It is possible that heavy resistance training may have to be implemented to overcome these findings. Correct indications and a careful preoperative evaluation are of fundamental importance for successful long-term outcome. The 3-in-1 procedure does not preclude further surgical stabilization, as do the Elmslie-Trillat procedure or reconstruction of the medial patellofemoral ligament, when failure occurs after skeletal maturity. Conclusion: The 3-in-1 procedure is a safe, reliable management option for recurrent patellar dislocation in skeletally immature patients. Long-term evaluation is necessary, particularly to monitor the possible development of patellofemoral osteoarthritis.