Unicompartmental knee arthroplasty with use of novel patient-specific resurfacing implants and personalized jigs

This paper describes the surgical technique with a patient-specific resurfacing unicompartmental knee arthroplasty. The patient-specific implant is currently designed on the basis of data from preoperative computed tomography. The implant is provided with a set of patient-specific, disposable cutting jigs. Biomechanical and anatomic axes are factored into jigs from a scan obtained through the hip, knee, and ankle, effectively achieving pre-navigation of the cut planes without the need for a navigation system. The surgical technique is reduced to five simple, reproducible steps. After removing the articular cartilage, the knee is balanced to determine the correct amount of tibial resection; this is followed by femoral preparation, verification of balancing and tibial preparation, and trial and cementing of the implant. The introduction of personalized three-dimensional image-derived resurfacing implants, as well as personalized single-use instrumentation, has the potential to change the common surgical practice of unicompartmental knee arthroplasty. Patient-specific resurfacing implants enable a femoral bone-preserving approach and enhance cortical bone support on the tibia, overcoming critical design limitations of commercial off-the-shelf implants. Patient-specific resurfacing implants can restore normal anatomy, the position of the joint line, and normal joint function, with the potential to result in more normal knee kinematics.