Number of patients willing to participate in the study too low

50 patients are randomized to two groups who receive a navigated knee prosthesis. Aim of the study is a comparison between a minimally invasive and a conventional approach. In both groups OrthoPilot computer assisted-navigation will be used. Pain intensity as well as concomitant pain medication are monitored during the first 20 postoperative days and will be compared for the two groups. Various scores are surveyed.

Accuracy of implant positioning and reconstruction of the mechanical leg axis are major requirements for achieving good long-term results in total knee arthroplasty (TKA). A minimally invasive approach might compromise the accuracy due to lacking intraoperative oversight. The purpose of this study is to compare a minimally invasive TKA approach that was performed under control of a navigation system with a standard navigated approach, with respect to patient pain and range of motion.

All patients receive a Columbus knee prosthesis and in both groups an OrthoPilot navigation system is used to control the alignment. Pain intensity using the Visual Analogue Scale (VAS) and concomitant pain medication intake are documented daily during the first 20 days after operation. As long as the patient is hospitalized the Range of Motion will also be documented daily. Knee society score, oxford score, as well as the WOMAC score are monitored pre- and postoperatively.

Inclusion Criteria:

• Indication for elective TKA
• agreement to participate in this study

Exclusion Criteria:

• Body Mass Index (BMI)>40kg/m²
• varus or valgus deformity >20°
• Range of Motion (ROM) <75° flexion/extension
• concomitant diseases like: rheumatoid arthritis osteoporosis intake of cortisone diabetes former operations on the concerned knee
• infections in the operated joint during the follow-up period
• Thromboses during the follow-up period