Inaccuracies in the assessment of femoral anteversion in proximal femoral replacement prostheses.

Accurately judging anteversion of proximal femoral replacement prostheses (PFRPs) during insertion can be difficult and may affect performance/stability. We designed a gravity goniometer jig, which attaches directly to the prosthesis, to improve rotational placement. Our hypotheses were that surgeons cannot accurately estimate anteversion in the context of a PFRP and that our jig would improve rotational placement. In our model, a 15-centimeter PFRP was placed in a saw-bones femur set in a lateral position. The prosthesis could rotate into anteversion/retroversion while the femur was fixed. Orthopedic residents and surgeons made 2 attempts to place the prosthesis into 15 degrees of anteversion; first without, then with the jig. Each attempt was recorded by photograph and angle-measuring jig. Nineteen surgeons and 28 residents participated. Without the jig, the mean PFRP anteversion was 18.3 degrees (range, 1 degrees -50.5 degrees ; SD, 9.6) compared to 14.3 degrees (range, 12.5 degrees -15.5 degrees ; SD, 0.7) using the jig (P = .006). Without a jig, the mean anteversion of resident-placed endoprosthesis was 18.4 degrees (range, 3 degrees -36 degrees ; SD, 8.1) compared to 18.1 degrees (range, 1 degrees -50.5 degrees ; SD, 12.1) (P = .91) recorded for attending physicians. The angle measurements from the jig and photographs were statistically equal. The placement of the PFRP into proper anteversion was more accurate with the aid of the jig. Simple jigs, such as the one developed for this study, may improve rotational placement of PFRPs.