A Repeatable Method for in-situ Joint Alignment of Disarticulated Human Knees During in-vitro Mechanical Testing

Accurate kinematic alignment is crucial for in-vitro biomechanical testing of human joints in a laboratory setting. Misalignment of knee joints leads to significant errors in joint kinematics and resultant forces, with joint alignment variations causing a 2-3 times increase in kinematic errors. For example, minor positional changes due to alterations in testing procedures, such as removing the joint from the testing apparatus, have been shown to cause significantly larger forces during position-control testing. Further, in total knee arthroplasty (TKA), joint misalignment can cause component loosening, increased wear, and early failure. For these reasons, accurate positioning of the knee joint is critical.

 

While previous in-vitro studies have developed methods to accurately align whole human knee joints prior to biomechanical testing, no such study has developed a method to re-establish natural alignment for disarticulated knees. Joint disarticulation, where soft tissue restraints are removed prior to testing, can be a necessary step in research that requires early access to the joint capsule. For example, meniscus and cartilage experiments may require imaging of these tissues prior to testing. Therefore, the objective of the current study is to define and quantify a method to repeatedly position disarticulated knees to their natural intact alignment (in-situ position).