Analysis of the bone surface area in resected tibia. Implications in tibial component subsidence and fixation.

Anterior subsidence of the tibial component is still a clinical complication requiring revision in total knee replacement. Using the scanning electron microscope, a quantitative 3-dimensional stereoscopic and digitizing study was conducted on the cortical and cancellous bone surface area from 10 resected human cadaveric tibia. The data demonstrated that the cortical bone surface area covered an average of 6% of the total tibial surface area, cancellous bone 18%, and bone marrow space 76%. By conducting anatomic regional analysis, the data showed significantly higher (p < or = 0.05) bone quantities in the posteromedial and medial regions as compared with the anterior and anterolateral regions. These data help to explain why tibial component subsidence occurs anteriorly in total knee replacement. The data also suggest that if long-term component subsidence and loosening is to be limited, either biologic cement or bone cement would be required to increase the surface attachment between the tibial component and resected cancellous bone.