Computer-assisted orthopaedic surgery: minimally invasive hip and knee reconstruction

Abstract

Conventional surgical techniques for joint reconstruction require large surgical exposures and extensive soft tissue dissection to visualize, access, and prepare the bone surfaces. Surgeons and researchers lack accurate measurement tools to assess the actual orientation of the implants, intra- and postoperatively [ 1 ]. Modern surgical interventions try to minimize the postoperative complications by maintaining high accuracy and safety standards during surgery and aim to increase technical reproducibility. Less and minimally invasive surgery (L/MIS) for joint reconstruction is an important development that promises significant changes in partial and total joint replacement. Eventually this would lead to the improvement of patient outcomes and possible long-term cost reduction of the treatment. There are also drawbacks that have emerged with the introduction of these new techniques, however, such as the prolonged learning curve, increased cost of equipment and disposable instruments, and longer operating times. There is a special concern about the accuracy of implant positioning and the possible additional complications when using small approaches. Performing total hip or knee replacement through 8–10-cm incisions is a more challenging task than conventional wide approaches. The surgeons have to perform precise bone cuts and correctly align the acetabular, femoral, or tibial components in a smaller workspace and without the usual landmarks. Some studies have proven the relationship between the alignment of the cup and polyethylene wear [ 2 , 3 ]. An inclination angle greater than 50° seems to increase polyethylene wear and subsequent pelvic osteolysis. Hip stability also is considered to be related to implant alignment. Morrey [ 4 ] and others consider cup orientation as a “critical variable” related to instability. Incorrect positioning or orientation of implants during total knee replacement surgery, poor soft tissue balancing, and improper alignment of the limb can lead to accelerated implant wear, loosening, and decreased overall performance [ 5 , 6 ]. An alignment error greater than 3° was shown to be associated with more rapid failure of total knee arthroplasties [ 7 ].