We have prospectively followed 18 patients having an opening wedge high tibial osteotomy for medial compartment osteoarthritis of the knee using the Puddu plate and autologous bone graft. The purpose was to assess the learning curve involved in the introduction of a new procedure and to follow its long-term success. Ethics committee approval was obtained.

Eighteen consecutive patients (4 female, 13 male, 1 bilateral, average age 47), operated on by 5 different surgeons were assessed pre-operatively using the American Knee Society knee and function scores and SF-36 health questionnaires. Radiographs were assessed using the Ahl-bach grading system for severity of degenerative change and the long-leg mechanical axis was measured as a percentage of total joint surfaces from the medial side.

Pre-operatively patients had an average Ahlbach score of 1.8 (range 1–3, mode 2). The long-leg mechanical axis average was 14.7% (range 3.75–27.5%), American Knee Society knee score average was 49.2 (range 28–64) and function score average 58.4 (range 40–70). By six weeks post-operatively all patients had at least 90 degrees of flexion and pain of less than 2 out of 10. There have been five complications: 1 deep infection requiring admission for intravenous antibiotics, 2 superficial infections requiring oral antibiotics only, and 2 intra-operative fractures, both internally fixed at the time of surgery. At follow-up of minimum 12 months the average mechanical axis was 50.6% (range 32–64%), Knee Society score 79 and function score 82.

These early results suggest that despite some complications this procedure is weII tolerated and gives good functional results.