[Surgical technique and early clinical outcomes of direct anterior approach to total hip arthroplasty].

Objective: To describe the surgical technique of direct anterior approach to total hip arthroplasty and to report the early clinical outcomes.
Methods: A series of 100 consecutive, unselected patients who had 116 primary total hip arthroplasty surgeries (16 bilateral) done through direct anterior approach from March 11 2015 to June 21 2016 was reviewed. There were 50 male patients and 50 female patients. The average patient age was 51 years, and the average body mass index was 24.69 kg/m ² . The preoperative diagnosis included avascular necrosis of femoral head, hip osteoarthritis, osteoarthritis secondary to acetabular dysplasia, sequelae of hip old infection, ankylosing spondylitis, rheumatoid arthritis and avascular necrosis of femoral head after cannulated screws fixation of femoral neck fracture. There were 7 hips which had surgical history prior to the index hip arthroplasty, including 3 cases with bone graft treatment for avascular necrosis of femoral head through Smith-Peterson approach, 2 cases with acetabular shelf procedures for acetabular dysplasia through Smith-Peterson approach, and 2 cases with cannulated screws fixation for femoral neck fracture (internal fixation residual). All were uncemented hips. The stems used in this study included 67 Triloc stems (DePuy company, USA), 45 Corail stems (DePuy company, USA), 2 Accolade stems (Stryker company, USA), 1 Synergy stem (Smith-Nephew company, USA) and 1 Polarstem (Smith-Nephew company, USA).
Results: The average follow up period was 8.5 months, the average incision scar length was 10 cm, and the average postoperative Harris score was 93.62. There was 95% postoperative leg length discrepancy within 3 mm. The average cup inclination angle was 38.7° with 94.8% in the range of 30° to 50°. The average cup anteversion angle was 14.3° with 94.2% within the target range of 5° to 25°.The were 15 (12.9%) operative complications, including two femoral perforations (changing stem from Triloc to Corail), three calcar fractures (treated with cerclage wires), four greater trochanter fractures (2 were treated wire tension band, and 2 nondisplaced fractures untreated), one deep infection (debridement and retaining of the prothesis), one superficial infection (debridement), one hematoma and three wound healing complications (debridement). All the complications were successfully treated without any sequelae at the end of the latest follow-up. There was no postoperative dislocation. There was no major nerve and vascular injuries. There were 35 cases (30.2%) reporting symptoms of lateral femoral cutaneous nerve palsy.
Conclusion: Direct anterior approach to total hip arthroplasty allows accurate and reproducible cup orientation positioning and leg length restoration and decreases the risk of postoperative dislocation, which is helpful for early rapid postoperative recovery.