Robotic-Assisted Total Hip Arthroplasty Is Associated With Lower Prosthetic Complications in Patients With Lumbar Fusion or Stiff Spine: A Propensity-Matched Cohort Study

BACKGROUND: Patients with spinopelvic risk factors such as lumbar fusion or stiff spine exhibit a 5- to 10-fold increased risk of dislocation following total hip arthroplasty (THA), primarily due to altered spinopelvic mechanics that influence cup positioning. The utilization of robotic-assisted THA facilitates personalized planning, enhancing component placement in this high-risk population. This study aims to compare rates of implant-related and medical complications between robotic-assisted and manual THA in these high-risk patients. METHODS: Data were retrospectively obtained from the TriNetX Research Network. Patients with prior lumbar fusion or spinal conditions associated with stiffness or malalignment, and who subsequently underwent THA, were identified using ICD-10 and CPT codes. Procedure codes defined robotic-assisted and manual THA. After 1:1 propensity score matching for age, sex, body mass index, smoking status, and other comorbidities, outcomes were compared at 3, 6, 12 months and 2 years. A subgroup analysis compared both groups in spinal fusion (SF) and nonfusion (no-SF/stiff spine) patients. RESULTS: After 1:1 propensity score matching, each cohort included 2,147 patients. At 3 months, robotic THA was associated with lower prosthetic complications (1.4 vs 2.7%; odds ratio [OR]: 1.86, 95%; P = 0.01) and postoperative blood transfusion (0.9 vs. 1.8%; OR: 2.02, P = 0.01). At 1 year, dislocation was reduced (0.9 vs. 1.8%; OR: 2.07; P = 0.01). Revisions were also lower at 1 and 2-year follow-up in the robotic group (1.7 vs. 2.7%, OR: 1.61; 2.0 vs 3.7%, OR: 1.86; all P < 0.05; respectively), and the manual group had 1.9 times the hazard of having revision surgery at 2 years (HR: 1.9, 95%; P = 0.02). In no-SF patients, robotic THA was associated with markedly lower rates of prosthetic complications and revision surgery. CONCLUSION: Robotic-assisted THA was associated with fewer complications than manual THA in patients with lumbar fusion or clinically relevant spinal stiffness, a population at elevated risk for instability after THA. Precision-based implant positioning may improve outcomes in patients with altered spinopelvic mobility, including those without spinal fusion.