Persistent Patellar Dislocation Following Correction of a Lower Limb Length Discrepancy: A Case Report.

Lower limb length discrepancy is common, but only a small proportion of cases are clinically significant. Distraction osteogenesis allows correction at any age without reducing final height, though long-term biomechanical consequences may arise. We report the case of a young patient who underwent femoral lengthening for a 4.5 cm discrepancy and, five years later, developed chronic patellar instability with persistent dislocation. Imaging revealed trochlear dysplasia, lateralization of the tibial tuberosity, medial patellofemoral ligament (MPFL) insufficiency, and increased quadriceps tension. A combined surgical approach was performed, including open trochleoplasty, distalization and medialization osteotomy of the tibial tuberosity, MPFL reconstruction, and quadriceps lengthening using a V-Y technique. At one-year follow-up, the patient achieved a pain-free range of motion of 0°-85°, with no recurrent instability and Lysholm and Kujala scores of 71 and 65, respectively. This case illustrates the importance of long-term follow-up after lengthening procedures and highlights the effectiveness of tailored, multimodal surgery in managing complex patellar instability.