Leg-Length Discrepancy After Total Hip Arthroplasty: Comparison of Robot-Assisted Posterior, Fluoroscopy-Guided Anterior, and Conventional Posterior Approaches.

Total hip arthroplasty (THA) effectively provides adequate pain relief and good long-term outcomes in patients with hip osteoarthritis. However, leg-length discrepancy (LLD) remains the most common cause of patient dissatisfaction and malpractice litigation in hip arthroplasty. We conducted a study to compare LLD in patients who underwent THA performed with a robot-assisted posterior approach (RTHA), a fluoroscopy-guided anterior approach (ATHA), or a conventional posterior approach (PTHA). We reviewed all RTHA, ATHA, and PTHA cases performed by Dr. Domb between September 2008 and December 2012. Patients included in the study had a primary diagnosis of hip osteoarthritis and proper postoperative anteroposterior pelvis radiographs available. Two blinded observers calibrated and measured all radiographs twice. After exclusions, 67 RTHA, 29 ATHA, and 59 PTHA cases remained in the study. There were strong interobserver and intraobserver correlations for all LLD measurements (r > 0.9; P < .001). Mean (SD) LLD was 2.7 (1.8) mm (95% CI, 2.3-3.2) in the RTHA group, 1.8 (1.6) mm (95% CI, 1.2-2.4) in the ATHA group, and 1.9 (1.6) mm (95% CI, 1.5-2.4) in the PTHA group (P = .01). When LLD of more than 3 mm was set as an outlier, percentage of outliers was 37.3% (RTHA), 17.2% (ATHA), and 22% (PTHA) (P = .06-.78). When LLD of more than 5 mm was set as an outlier, percentage of outliers was 10.4% (RTHA), 6.9% (ATHA), and 8.5% (PTHA) (P = .72 to > .99). No patient in any group had LLD of 10 mm or more. RTHA, ATHA, and PTHA did not differ in obtaining minimal LLD. All 3 techniques are effective in achieving accuracy in LLD.