The direct anterior minimal invasive approach in total hip replacement: a prospective departmental study on the learning curve

Introduction: Introduction of new surgical techniques is normal, but seldom monitored in real time. The purpose of this study was to monitor the learning curve when introducing a new surgical technique to a department. We did a prospective evaluation of the learning curve when introducing the minimally invasive direct anterior approach in total hip arthroplasty. We wish to investigate whether there is a learning curve for the direct anterior minimal invasive approach in total hip replacement and what are the early complications to this approach. Methods: The department changed from the direct lateral approach to the minimally invasive direct anterior approach. We monitored the first 522 patients operated using this approach with regards to patient outcome scores and complications 6 months postoperatively. Results: The last 250 patients operated all had significantly better results with regard to patient outcome scores and cup placement. We investigated 100 patients at a time and compared them with the rest of the patient and found the same pattern. This pattern ends when we reach patients somewhere between 200-300. Discussions: We established the learning curve on a departmental level with regards to introduction of the minimal invasive direct anterior approach. We see a steady improvement in scores with regards to patient outcome scores and cup positioning until we reach a steady-state. The learning curve here flattens out. Departments must understand that one should expect early complications and somewhat less than optimal results at first when introducing this new surgical technique.