Publication:

Impact of post-operative hip-knee-ankle angle changes on functional outcome of total knee arthroplasty: a prospective longitudinal study

Background Coronal malalignment as residual varus may have deleterious effects on functional outcomes of total knee arthroplasty. This study aimed at highlighting the impact of postoperative hip-knee-ankle (HKA) angle changes on the functional outcome of total knee arthroplasty.

Methods 689 total knee arthroplasty (TKA) knees (from 386 patients) with varus postoperative HKA angle were included. HKA angle was measured on standing orthoscanograms. The knees were divided into 5 subgroups according to postoperative HKA angle as: neutral (0±3.0 degrees); mild (3.1-6.0 degrees); moderate (6.1-10.00 degrees); severe (10.1-5.0 degrees); very severe (>15.0 degrees). Functional outcome of TKA in these subgroups was observed by knee society score (KSS), knee society pain score (KSS-P), Oxford knee score (OKS), lower extremity functional scale (LEFS) at 6 months, 1 year, 2 years, 3 years. Statistical analysis was done by statistical package for social sciences (SPSS) version 16; Spearman’s correlation coefficient and Kruskall Wallis test was used to compare the functional outcome of TKA between COHORTs.

Results 69 knees were present in the mild varus cohort (mean: -1.92), 223 knees in the moderate varus COHORT (mean: -4.77), 260 knees in the moderate varus COHORT (mean: -7.86), 121 knees in the severe varus COHORT (mean: -11.60) and 16 knees in the very severe varus COHORT (mean: -16.54). Mild to moderate varus knees were maximum, but no significant difference in functional outcome between these COHORTs was found by correlation analysis and Kruskall Wallis test.

Conclusions Changes in postoperative HKA angle (coronal alignment) has no significant impact on functional outcome of TKA.