[Comparison of early effectiveness between different approaches in primary total hip arthroplasty]

To compare the early effectiveness between by anterior approach via Bikini incision and by OCM approach in the primary total hip arthroplasty (THA).

Between June 2015 and March 2016, 60 patients with ischemic necrosis of the femoral head who accorded with the inclusion criteria were chosen in the study, who were divided into 2 groups according to different surgical approaches. THA was performed on 30 patients by anterior approach via Bikini incision (group A), and on 30 patients by OCM approach (group B). There was no significant difference in age, gender, body mass index, side of affected hip, Steinberg stage of ischemic necrosis of femoral head, preoperative hemoglobin, preoperative Harris score, and preoperative visual analogue scale (VAS) between 2 groups ( P>0.05). The operation time, length of incision, intraoperative blood loss, transfusion rate, starting time of straight leg raising exercise, starting time of active abduction of hip, hospitalization time, the incidence of limb length discrepancy, postoperative Harris score and VAS score were recorded and compared between 2 groups. Anteroposterior pelvic X-ray films were taken to measure acetabular abduction and acetabular anteversion.

Primary healing of incision was obtained in all patients of 2 groups, and there was no significant difference in complication between 2 groups ( χ²=0.144， P=0.704). All the patients of 2 groups were followed up 3 to 12 months, averaged 6 months. There was no significant difference in operation time, length of incision, intraoperative blood loss, transfusion rate, hospitalization time, and starting time of straight leg raising exercise between 2 groups ( P>0.05). Group A was significantly shorter than group B in starting time of active abduction of hip ( t=-4.591, P=0.000), and was significantly lower than group B in the incidence of limb length discrepancy ( χ²=5.455, P=0.020). After operation, neither Harris score at 2 weeks, 6 weeks, 3 months, and 6 months nor VSA score at 24 hours and 6 weeks showed significant difference between 2 groups ( P>0.05). The anteroposterior pelvic X-ray films showed that all the prostheses were in good position, and there was no femoral prosthesis subsidence, acetabular cup displacement or dislocation. No significant difference was found in acetabular abduction and acetabular anteversion at 2 days after operation between 2 groups ( t=0.887, P=0.379; t=0.652, P=0.517).

Both of two approaches in THA can avoid muscle damage and achieve favorable short-term effectiveness. But, anterior approach via Bikini incision is superior to OCM approach in starting time of active abduction of hip and the incidence of limb length discrepancy.