COMPUTER-ASSISTED DOUBLE OSTEOTOMY FOR MAJOR GENU VARUM: PRELIMINARY RESULTS IN 11 KNEES

Abstract

Purpose of the study: The purpose of this study was to assess radiological outcome of double (femoral and tibial) osteotomy for severe genu varum. Between August 2001 and November 2004, eleven double osteotomies were performed amoung a series of 157 knee osteotomies (7%).

Material and methods: The series included four women and seven men, mean age 48.5 years (range 20–62 years). The right knee was involved in seven. One femal patient presented a particularly serious deformity but without oseoarthritic degeneration of the knee joint. The ten other patients all presented overtly degenerative knees. According to the Ahlback modified classification there were six grade III knees, three grade IV and one grade V. Mean preoperative radiological varus was 167.5±2.1° (ange 164–170°°. Orthopilot® was used in all cases. The first step was to insert percutaneously rigid bodies, one into the distal femur and the other into the proximal tibia. Kinematic acquisitions of the hip, the knee and the tibiotalar joint yielded the HKA for the lower limb. The second step was to perform the closed wedge lateral femoral osteotomy (5–6°) which was stabilized with an AO T-plate. The final step was to perform an open-wedge medial tibial osteotomy. After checking the desired alignment (182±2°) on the monitor, the osteotomy was fixed with Biosorb® and plated with an AO LCP.

Results: There were no complications. The mean intraopeartive HKA was 168.1±2.21° (range 164–170°), identical with the preoperative findings. After osteotomy, the mean angle provided by the computer system was 182.7±1.1° (range 182–184°). Three months after surgery, the mean alignment on the standing x-ray was 180.8±1.6° (range 177–182°). The preoperative objective was achieved for all knees but one (91% success). There were no x-rays with an oblique joint space.

Conclusion: Computer-assisted double osteotomy for major genu varum is a reliable accurate and reproducible technique. Use of a navigation simplifies a generally difficult procedure known to require much surgical skill to achieve the preoperative goal. This technique can be considered as an important development since it can help avoid an oblique joint space which can give rise to further problems and the need for a subsequent prosthesis.