Minimally Invasive Hip Arthroplasty via SuperPath Approach in Obese Patients - A Prospective Study

The use of minimally invasive techniques for total hip arthroplasty (THA) in at-risk patients is still debated. The purpose of this prospective study was to determine the clinical and radiographic results of obese patients undergoing THA compared with those of normal-weight patients. Material and methods: A total of 476 patients of the 516 patients who underwent THA via the minimally invasive SuperPath approach between January 2016 and December 2019 attended the 1-year follow-up. Based on the WHO criteria for obesity, 22 patients were underweight, 147 were normal-weight, 186 were overweight, 73 were grade 1 obese, 25 grade 2 obese and 22 grade 3 obese. The clinical outcomes were evaluated using the Forgotten Joint Score (FJS). Radiographic analysis was performed with the digital software tool mediCad (HECTEC, Landshut, Germany).

The mean operating time was significantly longer at 81 min (55-96) in grade-3 obese patients than in underweight patients with 67 min (52-79; p = 0.01), normal-weight patients with 71 min (34-105; p = 0.04) and overweight patients with 70 min (50-100; p = 0.04). There were no significant differences between the six groups with regard to the hemoglobin drop between the preoperative state and the 2nd and 4th postoperative day. The mean "time to stairs" did not differ significantly (p > 0.05) between the six study groups. Normal-weight patients had a significantly lower inclination with 38.6° compared to overweight patients (40.3°; p = 0.04) and patients with grade 1 obesity (41.2°; p = 0.02). The inclination angles of patients with grade 2 (42.5°) and grade 3 obesity (42.6°) were highly significantly higher (p < 0.01) than in normal-weight patients. The mean anteversion angle of underweight patients (16.2°) was significantly lower than in normal-weight patients (17.6°; p = 0.03), overweight patients (17.8°, p = 0.02) and patients with grade 2 obesity (17.4°; p = 0.04). The mean anteversion angles in patients with grade 1 (18.3°) and grade 3 (18.1°) obesity were highly significantly higher than in underweight patients. The mean FJS-12 did not differ significantly (p > 0.05) between the six cohorts. Five patients had complications in the early postoperative period, three of whom were normal-weight.

The current study shows that obese patients undergoing THA via the minimally invasive SuperPath approach have equivalent complication rates and clinical and radiographic outcomes at the 1-year follow up compared with normal-weight and overweight patients.