Mechanical Bone Strength of the Tibial Resection Surface at Increasing Distance From the Joint Line in Total Knee Arthroplasty

Few articles have addressed the bone strength of the proximal tibia. This study attempts to quantify the compressive strength of bone in the proximal tibia of human cadaveric knees at increasing distance from the joint surface. Sixteen fresh-frozen human cadaveric knees were tested. The proximal tibia was sequentially sectioned into 1-cm slices, starting 2 mm below the chondral surface of the medial tibial plateau. Four slices were obtained from each knee. Each slice was then loaded to failure under an axial load. The proximal slice of bone had a significantly higher average maximum load to failure  than the more distal slices. The second, third, and fourth slices of bone withstood 77%, 61%, and 73% of the average load of the proximal slice, respectively. This study was designed to simulate how the proximal tibia is loaded under an uncemented tibial base plate after total knee arthroplasty. The results are in agreement with previous studies that have shown the proximal 1 cm of tibial bone to have the highest resistance to compressive loads. Previous studies on the bone strength of the proximal tibia have focused on more proximal portions of bone than the current study. This study demonstrates that the load to failure of tibial resection surface decreases significantly with increasing distance from the joint line until the 4th cm of bone beneath the joint line is encountered. This information may play a role in surgical decision making and implant design. (Journal of Surgical Orthopaedic Advances 13(4):195–198, 2004)