Abstract
Today controversy exists whether restoration of neutral mechanical alignment should be attempted in all patients undergoing TKA. The restoration of constitutional rather than neutral mechanical alignment may in theory lead to a more physiological strain pattern in the collateral ligaments, and could therefore potentially be beneficial to patients.
It was therefore our purpose to measure collateral ligament strains during three motor tasks in the native knee and compare them with the strains noted after TKA in different postoperative alignment conditions. Six cadaver specimens were examined using a validated knee kinematics rig under physiological loading conditions. The effect of coronal malalignment was evaluated by using custom made tibial implant inserts in order to induce different alignment conditions.
The results indicated that after TKA insertion the strains in the collateral ligaments resembled best the preoperative pattern of the native knee specimens when constitutional alignment was restored. Restoration to neutral mechanical alignment was associated with greater collateral strain deviations from the native knee.
Based upon this study, we conclude that restoration of constitutional alignment during TKA leads to more physiological periarticular soft tissue strains during loaded as well as unloaded motor tasks.
