Active_comparator: Manual Total Knee Arthroplasty

This group will receive a conventional manual Triathlon (Stryker) TKA with a cruciate retaining polyethylene insert. The surgeon will then make bone cuts using a manual jig and a hand held saw to prepare the bone surfaces for the implant. A measured resection technique will be employed with a three degree tibial slope. The surgeon will use a conventional jig alignment technique for intramedullary referencing for the femur and extra medullary referencing for the tibia. Once the implant is in position the knee is then balanced by the feel though a range of movement and soft tissue releases will be performed as required to balance the knee in flexion and extension.

Experimental: Robotic Assisted Unicompartmental Knee Arthroplasty

This group will receive the cemented Restoris MCK (Mako, Stryker) with a highly crossed linked (X3) polyethylene insert through a less invasive to the knee joint. Instead of using a manual jig and a hand held burr will be used to prepare the bone surfaces for the implant, the MAKO robotic arm will be used by the surgeon to cut the bone at the required alignment. The information from the CT scan will be used to create a 3D model of the patient's bony anatomy and will used to plan the positioning of the implant. Once the trackers are in place registration of the knee joint surface is performed. The specified bone cuts are then performed using the robotic arm, aiming to gap balance the knee through a full range of movement.