Surgical technique

A surgical technique was used as previously described by Koëter et al. [32] and slightly differs from the lateral facet elevating trochlear osteotomy as described by Albee and Weiker [33, 34]. In brief, the patient was placed supine on the table. Antibiotics were admitted preoperatively. No tourniquet was used. A lateral parapatellar incision was made and extended distally along the lateral femoral condyle. The retinaculum was opened in the direction of the femur. To visualize the osteotomy, two Kirschner wires were placed in the direction of the osteotomy till they were visible through the cartilage (halfway between the medial and lateral femoral facet). With the use of a small osteotome, an incomplete lateral trochlear osteotomy was carried out (Fig. ​(Fig.1).1). The curved osteotomy extended from the beginning of the trochlea proximally to the sulcus terminalis distally. Subsequently, the lateral articular surface of the trochlea was levered. In most cases, it was possible to raise the lateral articular surface by 4–6 mm. A wedge-shaped autograft was created with a part of the ipsilateral iliac crest to secure the elevation of the osteotomy; this graft was changed to a tricalcium phosphate (TCP) wedge during the study period (Fig. ​(Fig.2).2). Fixation of the osteotomy with osteosynthesis material was not needed. After performance of the osteotomy, the synovium was closed over while the lateral retinaculum was left open. Postoperatively, patients were placed on a continuous passive motion device (CPM) to stimulate a full passive range of motion until knee flexion was at least 60°. Patients were recommended the following training schedule: partial weight bearing for the first 6 weeks, without flexion limitation. After 6 weeks, full weight bearing was allowed. Patients were only referred to a physical therapist if restoration of normal gait was needed.

The osteotomy is performed with osteotomes; the proximal is further advanced medially than the distal osteotome

A triangular bone graft or tricalcium phosphate wedge is used to hold the achieved correction