Influence of Residual Varus Deformity on Clinical, Functional, Radiological and Dynamometric Outcomes of Total Knee Arthroplasty

Purpose of the study - to evaluate the influence of residual varus deformity of the lower leg on clinical, functional and dynamometric outcomes of TKR. Material and methods. In the period from September 2014 till May 2015 951 total knee replacement surgeries were performed in Ural clinical and rehabilitation center in 933 patients with initial varus deformity of lower limb. However, in 52 cases (5.5%) residual varus deformity of > 3 degrees persisted. The main group included 36 patients with mean residual varus deformity of lower leg of 3.9 degrees +/- 0.74 degrees (from 3.1 degrees to 5.6 degrees), the control group included 34 patients with neutral mechanic axis of the lower leg. Evaluation of treatment outcomes was performed on average 14.2 +/- 1.8 months after the procedure using functional assessment of the patients according to KSS (Knee Society Score), subjective assessment of life quality (SF36), as well as evaluation of the static- dynamic function of the lower leg on diagnostic and treatment complex Biodex Systems 4 Quick Set and assessment of stability of components fixation by F. C. Ewald scale in modification of O. A. Kudinov et al. Results. Functional assessment of the patients according to KSS (Knee Society Score) for the main group was 84.0 +/- 4.6, in control group -82.2 +/- 4.1 points (p> 0.05). Subjective assessment of life quality (SF36) in the main group was 162.6 +/- 6.4 points, in control group - 164.3 +/- 8.1 points (p> 0.05). In terms of flexion and extension of lower leg there were no significant differences between two groups when assessing static and dynamic function by treatment and diagnostic complex Biodex Systems 4 Quick Set >> on average in 14.2 +/- 1.8 months after procedure: neither isometric nor isokinetic parameters in both groups demonstrated statistically significant differences (p> 0.05). Based on X-rays evaluation there were no abnormalities in components fixation in both groups. There were no statistically significant differences identified in KSS and SF36 scales, dynamometry results and X- ray findings for stability of prosthesis (p> 0.05). Conclusion. The residual varus deformity in the knee of 3.9 degrees +/- 0.74 (from 3.1 degrees to 5.6 degrees) after total knee replacement in the patients with initial varus deformity of lower leg did not affect clinical, functional, X-ray and dynamometric outcomes in 14.2 +/- 1.8 months after the replacement.