WHO NEEDS NAVIGATION? A COMPARISON OF POSITION OF FEMORAL COMPONENT IN RESURFACING HIP ARTHROPLASTY

Abstract

Aim: The purpose of the study was to compare the position of the femoral guide wire for during hip resurfacing, computer navigation and an alignment device.

Materials and Methods: 26 cadaver specimens divided in 3 randomly selected groups and 25 patients were used to evaluate the position of the femoral guide wire in resurfacing hip arthroplasty. In two groups of cadavers the Computer Navigation was used to register and template the position of the implant. The position of the guide wire was compared to the one achieved using the alignment device. In the third group of cadaver specimens only the alignment device was used to implant the guide wire. Version was determined from the transversely cut sections of the cadaver specimens. Pre operative and post operative radiographs were used for analysis. In the patient group after registration and templating the guide wire was passed using the alignment device.

Results: There was no notching of the superior femoral neck in either of the groups. The mean and standard deviation of the anatomic neck-shaft angles was 124.91? ? 14.25?. The wire-shaft angle in the Navigation group was 131.46? ? 5.27? and in the alignment device group 134.08? ? 3.80?. In the navigation group the wire was in 0.85? ? 2.15? of retroversion as compared to 1.38? ? 4.19? of anteversion in Jig group. The position of the wires at the narrowest cross section of the femoral neck is shown in figure. The wire shaft angle as per navigation was 134.44(±5.55) as compared to 134.74 (±5.11).

Conclusion: The alignment device consistently positioned the wire more valgus and anteverted than Computer aided navigation. In all cases, the wire position was well within acceptable limits. Computer aided navigation does not seem to offer distinct advantages in resurfacing hip replacements.