Estimation of Femoral Version During Total Hip Arthroplasty: Surgeon Visual Assessment versus Robotic-Arm Assisted...

Malposition of THA implants can lead to many complications, some of which may necessitate reoperation. Thus, proper implant placement is critical for optimizing patient outcomes. In addition, intraoperative visual estimation of stem position has been shown to be unreliable. Therefore, the purpose of this study was to compare a surgeon's visual estimation of femoral version to the actual version captured using a three-dimensional robotic-arm assisted platform.

A prospective study of 25 THAs performed by a single surgeon was performed. The mean version, as estimated by intraoperative visual assessment, was compared to that measured by the robotic-arm assisted technology software using a two-sided t-test. Outliers were evaluated for the following intervals: 1 to 5°, 6 to 10°, and greater than 10°. A separate analysis was performed for anteverted versus retroverted stems.

The mean version, as estimated by intraoperative visual assessment, was 9.16 ± 4.02° (range, 3 to 18°) compared to 3.52 ± 8.66° (range, -12 to 19) as measured by the robotic-arm assisted software (P=0.005). The surgeon's estimates of broach version and those measured by the robotic-arm assisted software were identical in three cases (12%). The evaluation methods differed by 1 to 5° in six cases (24%), 6 to 10° in 10 cases (40%), and greater than 10° in six cases (24%). Larger differences between methods were noted for cases in which the stem was found to be in anteversion by the robotic-arm assisted software.

Visual estimation of femoral implant version differed significantly from measurements captured by three-dimensional robotic-arm assisted imaging. This suggests that estimating stem position intraoperatively by eye is not reliable, even when done by an experienced surgeon. The use of robotic-arm assisted technology may be recommended for determining femoral stem version intraoperatively.