Determining optimal medial-lateral resection angle for varus patients undergoing a total knee arthroplasty

Soft tissue and ligament imbalancing has been documented as a contributor to excessive wear in total knee arthroplasty (TKA). Conventional surgical techniques realign the varus proximal tibia to a neutral angle with the anatomical axis of the tibia during TKA. This modification can require additional operative procedures, including rebalancing of the ligaments and intraoperative alignment. David Scott, our collaborative surgeon, stated that he has "little to no need" to re-balance the ligaments when resecting a varus patient to 2° of varus during a primary TKA. Although an apparent clinical advantage, little was known as to how this resection technique might affect the properties of the cancellous bone, which are important since failure of bone can lead to instability and failure of the implant fixation. A collaborative study was conducted with Institutional Review Board (IRB) approval. The general hypothesis tested that resecting the proximal tibia of a varus patient at a 2° varus angle would not affect bone strength or trabecular orientation compared to a neutral resection angle. The study tested the compressive strength of cancellous bone as well as examined trabecular orientation/degree of anisotropy of the cancellous bone to determine if there were differences. Mechanical testing used a penetration method to measure compressive strength. Bone specimens were cut from the proximal tibia of the patient and sent from WA to UT