Post operative correlation of femoral tibial components with knee alignment using roentgenographic index in patients undergoing total knee arthroplasty in a tertiary referral centre

Abstract

Total knee arthroplasty is the leading surgical treatment for advanced osteoarthritis of the knee. Despite its efficiency, approximately twenty percent of the cases are dissatisfied with the outcome. Mal positioning of components results in loosening, which has long-term consequences. As a result, proper sizing and placement are important for optimal functional and long-term outcomes. Achieving limb alignment, good soft tissue balance and pain relief are the primary goals of the surgeon upon completion of total knee replacement (TKA). The aim of this study was to determine the accuracy of placement of femoral and tibial components post-operatively in relation to knee alignment using a roentgenographic index. This is a prospective study conducted in a tertiary care referral hospital, we included a total of fifty cases who underwent total knee arthroplasty from the year 2019 to 2020. Post-operative radiographic parameters were measured using digital software and compared using roentgenographic indexes as described by Lotke et al. Out of the fifty Total Knee Arthroplasty cases, twenty-eight knees had perfectly positioned tibial and femoral prosthesis, fifteen cases had good position of both the components. Tibial component alignment angle (β = 90°) in relation to mechanical axis in coronal plane was seventy six percent; fourteen percent of the cases were in native knee varus. Femoral component alignment angle (α) with acceptable anatomical valgus (0-7°) were more than eighty percent of the cases. 85.5 was the mean roentgenographic index which was strongly correlatable with other similar studies. With good clinical acumen and using conventional alignment system, near to normal knee alignment in total knee arthroplasty is achievable.