Total Hip Arthroplasty in Patients with BMI ≥ 30 kg/m2: BMI Evolution, Planning Accuracy, Restoration of Anthropometric Parameters and Clinical Outcomes

Background: Obesity is increasingly prevalent among patients undergoing total hip arthroplasty (THA). While outcomes are well reported, fewer studies assess postoperative BMI trends, digital templating accuracy, and biomechanical restoration. Purpose: To evaluate BMI evolution, templating accuracy, restoration of limb length and femoral offset, and clinical outcomes after primary THA in obese patients, compared with normal-weight controls. Methods: Retrospective comparative cohort including 75 obese patients (BMI ≥ 30 kg/m2) undergoing primary THA between July 2021 and December 2024. BMI was recorded preoperatively and at last follow-up. OrthoView™ 7.1 digital templating guided preoperative planning; accuracy was defined as implanted versus planned component sizes. Radiographic assessment of limb length and femoral offset was performed in 60 obese patients and 60 normal-weight controls. Clinical outcomes included Harris Hip Score (HHS), Oxford Hip Score (OHS), and EQ-5D-5L. Postoperative complications were recorded in the obese cohort. Results: BMI remained stable postoperatively (33.68 ± 2.57 vs. 34.06 ± 2.78 kg/m2; p = 0.138). Templating accuracy within ±1 size was high (femoral stem 80.2%; acetabular cup 94.7%). Limb-length discrepancy was low and comparable between obese and normal-weight patients (3.55 vs. 3.78 mm; p = 0.687). Femoral offset restoration was similarly comparable. Patient-reported outcomes improved significantly in both groups, with no significant differences in postoperative scores. Conclusions: In obese patients, THA provides reliable digital planning accuracy, satisfactory biomechanical reconstruction, and substantial functional improvement comparable to normal-weight patients. BMI remains essentially unchanged after surgery, indicating THA does not substantially influence postoperative weight trajectory in this population.