Robotic assisted total hip arthroplasty using the MAKO platform

Abstract

Surgeons want to perform a perfect total hip replacement (THR) with every operation. Human performance has limitations, especially when performing a mechanical operation in a biological environment. Recent suggested changes to improve outcomes have been large femoral heads and anterior incisions, but unfortunately neither has resulted in any scientific data that change has been effected. The scientific data does tell us that poor component positions and impingement are the source of increasing mechanical complications. Therefore, attempts to improve the surgeon's performance by precise quantitative knowledge in the operating room have been used. We discuss robotic guided navigation as a solution. This technology provides predictable and reproducible results.

Figures

Fig. 1

a The acetabulum is reamed with robotic guided navigation with the reamer constrained by a virtual haptic tunnel which prevents the surgeon from going off-line or too deep. The reamer stops if human error is made. The computer screen shows the angle of the reamer which only needs to be within 10° of desired numbers to create the correct hemisphere. The COR superiorly, medially, and anterior-posteriorly is defined and when the reamer achieves the correct COR the robot stops reaming. The robot is seen on the right-hand side of the figure and the surgeon’s hands hold the reamer. b The cup is connected to the robot and directed to the correct inclination and anteversion through a virtual haptic tunnel created by the robot. The computer screen will give the numbers achieved for inclination and anteversion and the haptic tunnel will not allow more than 5° variation from the plan

Fig. 2

a Preoperative planning of the acetabular cup position on the CT scan allows restoration of the COR of the hip with the cup. Any difference between the COR of the cup (green dot) and the native hip (magenta dot) can be factored into the reconstruction of the femur. The depth of reaming is determined to create the COR position. The acetabular anteversion can be adjusted after the femoral anteversion is known (femur is prepared first). The CT planned cup position is then superimposed on the x-ray as seen in the lower left corner. The acetabular bony geometry of the CT scan is confirmed intraoperatively by registration as seen in the lower right hand corner. b The femoral neck cut is determined by restoring the femoral head center for the stem implant used. Differences between the stem COR and the bony femoral COR can be factored into the leg length and offset. The modular head desired can be selected according to any differences needed to correct leg length and offset. A defined level of neck cut (green line), with the stageline of the stem implanted at this level, will restore the leg length and offset the surgeon chooses during preoperative planning

Fig. 3

The final screen at completion of the reconstruction shows all the quantitative numbers for component position and biomechanical reconstruction with the final numbers compared to the preoperative plan