Implantation of Femoral Stem of Total Hip Arthroplasty Using a Mini-Robot

Shon, Hyun Chul; Won, Chung Hee; Kim, Yong Min; Kim, Dong Soo; Park, Kyung Jin; Kim, Tae Hoon

Abstract

PURPOSE
To evaluate the feasibility and accuracy of the simple robotic surgical system to rasp the femoral canal in total hip arthroplasty, we investagated the fitness error and alignment error.
MATERIALS AND METHODS
Femoral canals of six human cadaveric bones, 12 pig bones, and 18 sawbones were reamed using the author's robot system. Radiographs and axial CT images were obtained after the operation. The fitness error(gap between the femoral stem and the surface of the femoral canal) and the alignment error(the angle between the longitudinal axis of femoral canal and the distal part of the stem) were measured. The anteversion was measured in axial view of CT scan.
RESULTS
The errors were measured at 3 levels; level A, in the upper third, level B, in the middle third and level C, in the lower third of the proximal part of the stem. The mean value of fitness error was 0.12 mm at level A, 0.20 mm at level B, and 0.29 mm at level C. In cadaveric femurs, the average alignment errors were 0.02 degrees in anteversion, 0.98 degrees of valgus in coronal plane, and 0.51 degrees of flexion in sagittal plane. The errors were -0.03 degrees, 0.31 degrees, and -0.36 degrees respectively in pig bones. The errors were 0.13 degrees, 0.14 degrees, and -0.27 degrees respectively in sawbones.
CONCLUSIONS
This robot system is relatively simple and cheap compared with ROBODOC system. It can be utilized for the rasping of the femoral canal during total hip arthroplasty.