RANDOMIZED TRIAL OF ABG II BIPOLAR HIP ARTHOPLASTY VIA A LESS INVASIVE ANTERIOR VS A WATSON JONES APPROACH

Abstract

Introduction: Less invasive surgical technique in THA is expected to minimize soft tissue damage and expedite rehabilitation. Due to this, it is now in widespread use in elective THA. The large geriatric patient population suffering a fractured neck of femur thereby would also benefit of this technique. Aim of this study was to evaluate if this technique is feasible in the non-elective setting of geriatric patients and if there are benefits regarding clinical and social outcome.

Patients and Methods: Study setup is a prospective randomized trial with a positive Ethical Committee vote. Included were patients under legal care of a third party. Inclusion criteria were the indication for bipolar hip arthroplasty including grade ASA 4; exclusion criteria included neoplastic disease and rheumatoid arthritis. Setting is a large university hospital. After biometrical evaluation, each arm was set as 30 patients. Primary end point was the modified Barthel index. 48 patients were female. Mean age for female patients was 85.5, for male 82.9 years. There was no detectable difference in the groups regarding age, sex and BMI. As a less invasive approach, the well described „Direct Anterior Approach-DAA”(modified Smith-Petersen approach) was chosen. In the other arm the Watson-Jones approach was used. The ABG II stem with a bipolar UHR head (Stryker) were used in both groups. To minimize the learning curve, 10 cadaver- and 15 clinical procedures were performed with the DAA approach before the study. The pre- and postoperative regimen was identical in both arms. The modified Barthel index and other clinical parameter were determined preoperatively and at 4 postoperative intervals up to 40 days.

Results: There were no statistical differences between both groups for intra- and postoperative complications. The mean theatre time was 4.8 minutes longer for the DAA group, in the first 10 patients this difference was measured with 16 minutes. The Barthel Index was only statistically different at 40 days, at this time the DAA patients had reached their preoperative mobility level whilst the conventional approach patients (with a pre-operative level of 42.5) were measured with 25 points. The hemoglobin levels on day 5 and 16 were significantly different with a higher Hb for the DAA group. All other parameters showed no significant difference.

Conclusion: The DAA approach has a clear learning curve. Once this has passed, the theatre time is only slightly longer. There is a detectable benefit regarding early rehabilitation and a slight but significantly reduced blood loss.