Complete Trochlear Aplasia in the Knee—An Extreme Form of Trochlear Dysplasia

Case: A 39-year-old healthy woman without known genetic condition presented with bilateral patellar dislocations. Imaging demonstrated complete absence of the trochlear groove, defined as trochlear aplasia. Surgical treatment was initially performed on the left knee with refixation of an osteochondritis dissecans lesion, medial patellofemoral ligament reconstruction, and medializing tibial tubercle osteotomy. Intraoperative confirmation of the absence of trochlear groove made trochleoplasty unfeasible. At the 1-year follow-up, VAS was 0/10 without patellar dislocation. Conclusion: Trochlear aplasia represents an extreme form of trochlear dysplasia and poses diagnostic and surgical challenges because conventional measurements and trochleoplasty cannot be applied.