Effect of Coronal Alignment on 10-Year Survivorship of a Single Contemporary Total Knee Arthroplasty

Debate remains regarding the utility of mechanical axis alignment as a predictor of durability after total knee arthroplasty (TKA). Our study aimed to assess the effects of coronal alignment on implant durability, clinical outcomes, and radiographic results with a single fixed-bearing TKA design. All patients undergoing primary cemented TKA of a single design (Stryker Triathlon) from 2005-2007 with >10 years of follow-up and available pre-operative and post-operative hip-knee-ankle radiographs were included (n = 89). Radiographs were measured to determine coronal alignment and assessed for loosening. Mean preoperative mechanical axis alignment was -6 degrees +/- 6.7 degrees (varus, range, -16 degrees-23 degrees), while mean post-operative alignment was -1 degrees +/- 2.7 degrees (varus, range, -3 degrees-15 degrees). The aligned group was defined as knees with a post-operative mechanical axis of 0 degrees +/- 3 degrees (n = 73) and the outlier group as those outside this range (n = 16). No patients underwent revision. Ten-year survivorship free from any reoperation was 99% and 100% in the aligned and outlier groups, respectively (p = 0.64). Knee Society scores improved significantly in both groups (p < 0.001) and did not differ at final follow-up (p = 0.15). No knees demonstrated radiographic evidence of loosening. Post-operative mechanical axis alignment within 3 degrees of neutral was not associated with improved implant durability, clinical outcomes, or radiographic results at 10 years following primary TKA.