Abstract
A 10° deviation from the ideal cup orientation in Metal on Metal (MoM) bearing couples leads to increased wear and the subsequent risk of early revision surgery. We assessed the accuracy of orthopaedic trainees and consultants in achieving optimal acetabular cup orientation.
49 trainees and 18 consultants were asked to orientate an acetabular component to 40° inclination and 20° anteversion in 3 consecutive pelvic models:
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osteoarthritic (OA),
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OA with anterior pelvic tilt,
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OA with soft tissue cladding, the task most realistic of a surgical scenario.
The trainee group experience in performing hip arthroplasty procedures ranged from novice to expert (> 100 procedures performed). Performance was measured using an image based navigation system.
Average angular error in all tasks was less than 10°, but the range in anteversion or inclination was up to 65°. Eighteen percent of trainees were +/− 10° of the target orientation in Station A, 29% in B and 2% in C. Forty four percent of consultants achieved the safe zone in A, 16% in B and 0% in C. There was no significant difference in accuracy between the two groups in any of the tasks (p> 0.01). There was no correlation between experience and angular accuracy.
We have been unable to demonstrate trainees have the ability to achieve the optimal cup orientation in a clinically relevant safe zone. A similar range of error is found in experienced surgeons. Focused training or intra-operative computer assistance may provide the solution to improving accuracy in this core orthopaedic skill.
Correspondence should be addressed to Mr K Deep, Consultant Orthopaedic Surgeon, Golden Jubilee National Hospital NHS Trust, Beardmore Street, Clydebank, Glasgow G81 4HX, Scotland. Email: caosuk@gmail.com
