Predictors and Functional Implications of Change in Leg Length After Total Knee Arthroplasty.

BACKGROUND: Leg lengthening occurs in 83% of primary total knee arthroplasty (TKA). The effects of leg length discrepancy (LLD) on THA patients are well established. However, patient function and satisfaction associated with LLD after primary TKA has not been analyzed. This study aimed to quantify the magnitude of limb lengthening, identify radiographic and perceived LLD, and correlate these with predictive factors and functional outcomes in a series of TKA patients.

METHODS: Patients undergoing primary TKA who met inclusion criteria were prospectively enrolled in this study. Leg length measurements were measured on standardized preoperative and postoperative long leg radiographs. Patients completed preoperative and 6-month postoperative Knee Society Score and functional Knee Injury and Osteoarthritis Outcome Score, as well as a postoperative satisfaction and customized leg length-specific functional questionnaire.

RESULTS: Ninety-one patients undergoing TKA surgeries were included. Mean overall lengthening was 3.5 mm (range, -31.0 to 21.4 mm; SD, 8.4) with 77% of limbs lengthened; 89% of patients had no LLD (defined as ≥10 mm) after TKA. Postoperative radiographic LLD was associated with increased preoperative LLD (P < .001). Perceived postoperative LLD was associated with female gender (P = .02), decreased satisfaction (18% vs 84%; P < .001), and poorer functional score changes. Perceived LLD was not associated with radiographic LLD.

CONCLUSION: Radiographic lengthened LLD is uncommon after primary TKA (11%) and does not correlate with perceived LLD. Patients with perceived LLD have decreased satisfaction and functional score improvements after TKA surgery.