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BACKGROUND: Patient obesity is a risk factor for poor acetabular cup positioning in total hip arthroplasty (THA). OBJECTIVE: To assess the impact of using a novel, fluoroscopy-based robotic THA system on acetabular cup placement in obese versus non-obese patients. METHODS: A review of 105 consecutive manual unassisted (mTHA) (47 Obese/58 Non-obese) and 102 robotic-assisted (RA-THA) (50 Obese/52 Non-obese) primary, direct anterior approach THA procedures was conducted. All cases were performed by a single surgeon, for a pre-operative diagnosis of osteoarthritis, avascular necrosis, or rheumatoid arthritis. Obesity was defined as a Body Mass Index (BMI) ⩾ 30 kg/m2. Outcomes included acetabular cup inclination and anteversion, and the proportion of cups within the Lewinnek safe-zone. RESULTS: Obese patients in the mTHA cohort had larger cup inclination angles on average compared to non-obese patients (44.82∘ ± 6.51 vs. 41.39∘ ± 6.75; p = 0.009). Obese mTHA patients were less likely to have cup placement within the Lewinnek zone compared to non-obese mTHA patients (0.48 vs. 0.67; p = 0.027). Obesity had no effect on the accuracy of RA-THA. CONCLUSION: Obesity affects the placement of the acetabular component in manual THA. The novel, fluoroscopy-based robotic THA system in this study demonstrated accurate cup placement regardless of obesity status. [ABSTRACT FROM AUTHOR]

BACKGROUND: Robotic assistance in total hip arthroplasty (RA-THA) has been shown to minimize laterality-based differences in acetabular cup positioning. OBJECTIVE: To determine if the use of a novel, fluoroscopy-based RA-THA system mitigates differences in acetabular cup placement between left (L) and right (R) side hip procedures, when compared to manual, fluoroscopic-assisted technique. METHODS: We conducted a retrospective review of 106 consecutive mTHA (40 L/66 R) and 102 RA-THA (48 L/54 R) primary direct anterior approach procedures. All cases were performed by a single right-hand-dominant surgeon, for a pre-operative diagnosis of osteoarthritis, avascular necrosis, or rheumatoid arthritis. Outcomes included acetabular cup inclination and anteversion, and the proportion of cups within the Lewinnek safe-zone. RESULTS: The average inclination of mTHA L cases was smaller than that of mTHA R cases (41.10∘ ± 7.38 vs. 43.97∘ ± 6.27; p = 0.04). For RA-THA, L and R cup angles were similar. There were fewer overall mTHA hips within the Lewinnek safe-zone compared to RA-THA (0.59 vs. 0.78; p = 0.003), as well as fewer mTHA R cases than RA-THA R cases (0.59 vs. 0.80; p = 0.03) within safe zone. CONCLUSION: Use of a novel, fluoroscopy-based robotic system mitigates laterality-based differences in acetabular cup placement that were observed in a manual, fluoroscopic-assisted cohort. [ABSTRACT FROM AUTHOR]