Abstract
Aims: To determine the precision of conventional versus computer assisted techniques for positioning the acetab-ular component in total hip arthroplasty (THA). Methods: Using a lateral approach, 150 cups were placed by 10 different surgeons in 10 identical plastic pelvis models. Only the immediate operating þeld was visible. Preoperative planning was performed with a computerized tomographic scan. Fifty cups were placed free hand, 50 others with the standard cup ancillary, and the remaining 50 cups using computer-assisted orthopaedic surgery. The accuracy of cup abduction and ante-version was assessed with an electromagnetic system. Results: Using conventional techniques, free hand placement revealed a mean precision of cup anteversion and abduction of 10¡ [range: 5.5–14] and 3.5¡ [2.5–5] respectively. With the cup positioner, these angles measured 8¡ [5–10.5] and 4¡ [3–5.5] respectively, and using the computer assisted method, the mean cup anteversion precision was 1.5¡ [1–2] and mean cup abduction measured 2.5¡ [2–3.5]. Conclusions: Computer assisted cup placement is a very accurate and reproducible technique during THA. It is clearly more precise than either of the two traditional methods of cup positioning, even for well-trained surgeons.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
