Navigation assisted total knee arthroplasty - Evaluation of correction of clinico - Radiololgical parameters in substantial varus deformity

Abstract

Background: In the present scenario arthritis of knee joint is inevitable. Total- knee replacement is the final solution in severely deformed joints for pain free mobility. Longevity of the replaced joint is mainly dependent on good mechanical alignment. The navigation system was introduced with a claim to achieve near normal parameters of weight bearing axis thereby increasing the life of implanted knee. Material and Method: This was a prospective study from January 2012 to August 2015 done in Department of Orthopaedics at our institute. A cohort of 20 patients were taken with varus deformity more than 15 degree and operated with the help of navigation system. The result were compared with a cohort of 20 patients suffering from more than 15 degree varus deformity and operated without navigation. Informed consent was taken. Clearance from ethical committee of the institute was taken. Patients were evaluated pre operatively and post operatively at 1, 3, 6 and12 months post operatively with the help of knee society knee score and function score and radiographically. Results: Using computer assisted navigation and measured resection technique of ligament balancing in total knee replacement, mean tibio-femoral angle of 16.40 degrees varus preoperatively (range, 15degrees -24 degrees) was corrected to 2.4 degrees varus (range 5 degree valgus- 4 degree varus) postoperatively. Mean Knee Society score improved from 23.4 (range 0-44) to 86 (range 72 -98), and function score from 21 (range, 0-46) to 98.50 (range 55-100) at 12 months (range 12 month -34 months).No patient reported significant instability. Correction of severe varus deformity by the technique reported can successfully restore alignment, pain free motion, and stability. Conclusion: Substantial Varus knee deformity is very well corrected when total knee arthroplasty is done with the help of navigation system. Here, in our study, either no varus or residual varus deformity was 1-2 degree. Navigation system assisted surgery produces good functional outcome and near normal radiological parameters.