EUROPEAN JOURNAL OF MEDICAL RESEARCH 447

Objective: High tibial osteotomy (HTO) is one treat-ment option for young and active patients with uni-compartmental osteoarthritis. The success of this pro-cedure substantially depends on the degree of correc-tion of the mechanical axis. Computer-assisted naviga-tion systems are believed to improve the precision of axis correction through intraoperative real-time moni-toring. This study investigates the accuracy of limb alignment measurements with a navigation system on a cadaver specimen. Materials and methods: The measurements were per-formed on a well-preserved cadaver specimen with a mechanical leg axis of 4 ° varus. Data was collected during the HTO workflow. Repeated serial measure-ments were undertaken by four different surgeons. After these measurements, different landmarks were deliberately set at the wrong place to examine the in-fluence of mistakes during registration. Results: There was a high intra- and interobserver reli-ability with a mean mechanical leg axis of 3.9 ° ± 0.7° and a mean error of 0.6°. The grossly incorrect place-ment of landmarks for knee and ankle center resulted in an incorrect mechanical leg axis of 1 ° valgus up to 10 ° varus. Conclusion: The computer-assisted navigation system provided precise information about the mechanical leg axis, irrespective of the observer's experience