The classical longitudinal incision used for the direct anterior approach (DAA) does not follow the relaxation tension lines of the skin and can lead to impaired wound healing and poor scar cosmesis. The purpose of this study was to determine patient functional and radiographic outcomes of a modified skin crease “bikini” incision used for the DAA in THR.

964 patients (51% female; 59% longitudinal, 41% bikini) completed 2 to 4 years after surgery a follow-up questionnaire including the Oxford Hip Score (OHS), the University of North Carolina 4P scar scale (UNC4P), and two items for assessing aesthetic appearance and symptoms of numbness. Implant position, rates of radiographic heterotopic ossification and required revision were assessed.

UNC4P total (p<0.001) and OHS (p=0.013) scores were better in the bikini compared the longitudinal group. The proportion of aesthetically very satisfied patients was higher (p<0.001) in the bikini group. The proportion of patients reporting numbness in the scar was higher (p<0.001) in the longitudinal (14.5% versus 7.5%, respectively). Radiographic cup abduction angles, stem position and ectopic ossification rates did not differ between the groups. No differences in the revision rates of both groups being 2.1% in the longitudinal and 1.5% in the Bikini group. Although differences were not huge, Bikini incision resulted in better patient-related outcomes and satisfaction related to the scar. Our study showed that a short oblique “bikini” skin crease incision for the DAA can be performed safely without compromising implant positioning or increasing symptoms suggesting lateral femoral cutaneous nerve dysesthesia. As it is less extensile it should be used after having gained significant experience with the classic longitudinal incision.