Abstract
Background
Total Hip Arthroplasty (THA) using the Direct Anterior Approach (DAA) is a muscle sparing approach which promotes early mobilisation of patients. It is a technically challenging approach shown to have a high rate of complications, especially during the learning curve. Here we present the results of 157 cases of THA via a DAA on a standard theatre table, with a minimum of 6 months follow-up.
Materials & Methods
The authors conducted a prospective study on a group of 149 consecutive patients undergoing 157 cementless primary THAs for coxarthrosis, 8 bilateral. The same surgical technique was used in all patients, performed by the senior author WLW at a single centre. The average age of the patients at time of surgery was 69 years, 78% were female and 57% were right sided. All implants were uncemented, with bearings being ceramic on ceramic or Ceramic on highly cross-linked polyethylene. Patients were assessed clinically and radiographically pre- and post-operatively at 6 weeks, 6 months, 1 and 2 years. Intra-operatively, navigation was used to guide cup position and assess offset and leg length.
Results & Discussion
At the time of the latest follow-up, 1 patient had died of unrelated cause and 8 (5%) were lost to follow-up Clinically, the mean Harris Hip Score was 91 points with 88% reporting a good or excellent result, with 5% reporting moderate to severe pain. Radiographically all patients assessed had evidence of stable bony ingrowth. There was subsidence of 2–5mm in 9 stems (6%). Osteolysis was reported adjacent to one cup and one stem. There were no dislocations. The complication rate was 4.5%. This included 2 intra-operative femoral fractures, one a minor greater trochanteric fracture not requiring fixation, the other a calcar fracture treated at time of surgery. There were 3 femoral fractures occurring on average 4 weeks after surgery all requiring revision and one stem subsidence of 10mm following a heavy fall, subsequently requiring revision for leg length discrepancy. Other complications included one non-fatal PE, a haematoma that required evacuation. We report 20 (12%) episodes of lateral femoral cutaneous nerve palsy of any severity, most of which had or were resolving at the 6 month follow-up. Kaplan Mieir survival analysis was 97.2% at minimum 6 months
Patients mobilised day of surgery or day 1 post-op, and were discharged on average day 4 post-op. Neither the intra- or post-operative fractures could be attributed to the learning curve. Similarly episodes of stem subsidence and LFCN palsy occurred spread out over the 3 years of the study. This study supports the existing orthopaedic literature reporting the benefits of the DAA for THA with reduced soft tissue damage, reduced blood loss and early mobilisation with a low incidence of dislocation. Other authors however have reported a high incidence of complications attributing them to the early learning curve.
This early study of DAA using a standard theatre table has identified that complications of fracture, stem subsidence and LFCN injury can occur at any time and bear no relationship to a learning curve.
