Author(s): Charles Wallace


Background: Robotic arm assisted Total Knee Arthroplasty (TKA) is associated with improved accuracy of achieving the planned femoral and tibial implant positioning, joint line restoration, limb alignment, and posterior tibial slope compared with conventional jig-based TKA. Conversion of a unicompartmental knee arthroplasty (UKA) to TKA can potentially be challenging due to the bone loss involved. This often requires an augment on the medial side to ensure restoration of the joint line to the primary level. We report a technique using robotic arm assisted surgery to revise uni-compartmental knee arthroplasty to total knee arthroplasty. This has not been presented in meetings to date.

Case Presentation: We present 4 cases where medial UKA were converted to TKA.In order to register the patient’s’ anatomy intra – operatively, an accurate bony model is generated from a CT scan. The CT-scan is taken according to a specific CTprotocol which yields a very accurate 3D reconstruction of the knee. Bone registration was performed by mapping osseous landmarks displayed on the computer screen to verify the anatomy and establish the bony geometry with the UKA implant in-situ. Intraoperative kinematic data were used to further fine-tune bone resection and implant positioning using the robotic computer software. An intraoperative surgeon-controlled robotic arm (Mako Surgical,
Kalamazoo, Michigan) with visual, tactile, and audio feedback was then used to execute the planned femoral and tibial bone resections.

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