Robotic Arm Assisted Total Knee Arthroplasty in Patients with Flexible versus Fixed Deformities

Introduction: A total knee arthroplasty aims to achieve a stable, well aligned, and balanced knee through range of motion. Arthritic knees with rigid alignment can be challenging to balance reliably by both measured resection and gap balancing techniques. Titration of soft tissue releases can be difficult to reproducibly assess, resulting in over- or under-releases. The robotic arm platform has recently introduced a novel concept of knee balancing by implant manipulation. Materials and methods: We illustrate the use of robotic arm technology to address flexible deformities and present a “skim cut protocol” to correct rigid deformities. The protocol proposes a preliminary proximal tibia cut, as well as distal femur and posterior femur cuts for a component one size larger than the planned implant. The knee is then balanced as in flexible deformities and final cuts are made to achieve normal alignment. Conclusion: The skim cut protocol effectively restores alignment of rigid knees while minimizing soft tissue releases.