| Description |
Revision of total knee replacement (TKR) is more difficult and less successful than primary TKR. Surgeons claim that a decrease in bone from proximal to distal levels of the upper tibia is a major cause for the discrepancy between primary and revision TKR results. This research first outlined the anatomy, history, and current methods in total knee replacement, which are similar for primary and revision TKR. Important differences between primary and revision TKR were noted in this section. Then, through careful measurement and analysis of ten tibias at 5 levels, 1 level relevant to primary TKR, and the other relevant to revision TKR, the differences in total, cancellous, and cortical bone at these levels were determined. The results of this study showed that there is a significant difference in total cross-sectional area between levels of primary TKR (6 mm) and revision (12mm-30mm) TKR between 12 mm and 18 mm below the lowest articulating surface of the tibial plateau. The total area continued to decrease through 30 mm. Cancellous bone also began to decrease significantly between 12 mm and 18 mm and continued to do so through 30 mm. Cortical bone area decreased significantly between 6 mm and 12 mm because the posterior cruciate ligament insertion skewed the cortical bone area at 6mm. Cortical bone area then increased from 12 mm to 24 mm to 30 mm. The decrease in total area supported the suggestion that revision TKR is more difficult than primary TKR because of a decrease in bone in the proximal tibia. The increase in cortical bone suggested that for revision TKR especially, it is important that the tibial component of TKR cover the entire cortical rim. |
