Preservation of the lateral femoral circumflex artery in total hip arthroplasty using the bikini-type direct anterior approach : effect on muscle status and clinical outcomes.

Aims: The direct anterior approach (DAA) is increasing in popularity as a minimally invasive technique for total hip arthroplasty (THA). DAA-THA involves ligation of the ascending branch of the lateral femoral circumflex artery (a-LFCA), considered to contribute to the blood supply of the tensor fasciae latae (TFL) muscle. To determine the morbidity of these surgical steps, periarticular muscle status and clinical outcomes were assessed after bikini-type DAA-THA with a-LFCA preservation versus ligation. Methods: We evaluated the surgical records of 140 patients undergoing DAA-THA with continuous attempt of a-LFCA preservation from May to October 2021. A total of 92 patients were eligible and 46 consented to study participation (n = 20 preservation, n = 26 ligation). Preoperative and six-week clinical and radiological data were retrospectively extracted from patient files, and patient-reported outcome measures (PROMs) from the institutional registry. Clinical and MRI examinations were performed two years postoperatively to analyze volume and fatty infiltration of the TFL, gluteus medius, and gluteus minimus relative to the contralateral hip. A total of 13 patients underwent contralateral THA and were excluded from the analysis of muscle status. Results: Coxa valga morphology and less muscular habitus were more frequent in a-LFCA preservation. After a-LFCA preservation, less anterolateral soft-tissue swelling was described at six weeks (p < 0.001) and TFL local pain at two years (p = 0.034) postoperatively. PROMs did not differ between groups. Mean TFL volume side-difference was not significantly different after a-LFCA preservation (p = 0.276), but it was significantly different after ligation (11.6% smaller (SD 15.5); p = 0.022). TFL fatty infiltration side-difference was larger after a-LFCA ligation (p = 0.010). Muscle status of the gluteus medius and minimus did not differ between sides and groups. Conclusion: a-LFCA preservation had a minor effect on TFL muscle status. Since preservation was primarily feasible in hips with simpler morphology, it remains uncertain whether differences were due to preserved vascularity or reduced TFL injury. Hence, a-LFCA preservation does not appear essential. However, until further evidence becomes available, attempting a-LFCA preservation may be advisable.