Perceived Leg-Length Discrepancy After Primary Total Knee Arthroplasty: Does Knee Alignment Play a Role?

Leg length discrepancy (LLD) is common after total knee arthroplasty (TKA) although its incidence has not been well documented. The purpose of this study was to determine the incidence of perceived LLD before and after primary total knee arthroplasty as well as to determine the correlation between mechanical axis of the knee and perceived LLD. The incidence and time frame of resolution of postoperative LLD was also assessed. Seventy-three patients were prospectively enrolled. Evaluation included patient surveys regarding perceived LLD preoperatively, and at 3- to 6-week, 3-month, 6-month, and 1-year visits. Mechanical axis radiographs were obtained and the relationship of mechanical axis in patients with and without perceived LLD, both before and after surgery, was determined. Analysis was also performed for separate varus and valgus deformities. The effect of surgery on patients' perception of LLD was also determined. Fifty-three patients did not perceive a LLD preoperatively and 18 perceived a LLD preoperatively. Sixty-four patients did not perceive a LLD postoperatively and 7 patients perceived a LLD postoperatively. There was a significant difference in patients who perceived LLD preoperatively and those who perceived LLD postoperatively (P = .035). Of the 7 patients with a perceived LLD postoperatively, all noted resolution of LLD at a mean of 8.5 weeks. There were no statistically significant correlations of knee alignment to perceived LLD in any patient groups. Body mass index and age did not demonstrate any statistical differences between patient groups. Perceived LLD is common in patients undergoing TKA; however, perceived LLD decreases after surgery. Although approximately 10% of patients perceive a LLD after surgery, the vast majority resolve within 3 months. Our study did not show any relationship between mechanical knee alignment and perception of LLD.