Objective: Deceleration of the progression of medial gonarthritis via transfer of the mechanical load axis from the medial to the lateral femorotibial compartment and by reduction of compressive stresses in the medial compartment.
Indications: Isolated early-stage unicompartmental medial gonarthritis. Symptomatic varus deformity. Adjustment of the mechanical load axis in reconstructive surgery such as autologous chondrocyte transplantation. Correction of posttraumatic varus deformities.
Contraindications: Concomitant patellofemoral arthritis, lateral femorotibial arthritis, or other painful conditions of the knee. Limited range of motion. Knee instabilities, since a rapid development of a tricompartmental gonarthritis is likely to occur. Advanced osteoporosis. Poor peripheral circulation with an absent foot pulse. Lateral meniscectomy.
Surgical technique: Lateral approach. Subcapital osteotomy of the fibula. Preparation of the lateral tibial head. Partial osteotomy of the proximal one third of the tibial tuberosity. Marking of the joint line. A semitubular plate is placed over a guide wire parallel to the joint line, 1.5 cm distal to it, and is gently hammered into the tibial head with just the last hole seen outside. The lateral end of the plate is bent downward. Ascending osteotomy of the tibial head in an inferolateral to craniomedial direction. The osteotomy starts 2.5 cm distal to the plate and ends directly below the guide wire. The medial cortex remains intact. Excision of a lateral-based bone wedge according to the preoperative planning. The osteotomy is gently closed under valgus stress. A 4.5-mm cortical screw is aimed through the lateral hole of the plate into the distal fragment of the tibia and tightened until the osteotomy is brought under compression.
Postoperative management: During hospitalization, there is a periodic treatment with continuous passive motion without any limitation of range of motion and isometric training is taken up. Mobilization is permitted with partial load of 15 kg with two crutches during 6 weeks postoperatively. Ambulatory physical training with active and passive motion exercises. After 6 weeks, the load can be increased stepwise depending on the consolidation as seen on the control radiographs. Full weight bearing is generally reached after 10 weeks. During this time, thromboembolism prophylaxis with low-molecular-weight heparin is necessary.
Results: A retrospective analysis of the own patients treated with the described surgical technique was performed. On the basis of Kaplan-Meier survival analysis, it could be demonstrated that there is a correlation between the patients' level of activity and the long-term survival rate 10-15 years after the osteotomy. Moreover, the extent of correction has a direct influence on the long-term result.