A Novel Method for Calculation of Knee Deformation Angles in Clinical and Sport Biomechanics

Biomechanical analyses seek to improve understanding of the mechanisms of knee injury and to find ways to reduce knee injury incidence. Many clinical biomechanics researchers use a standard kinematic adopted from Newington Children’s Hospital. Biomechanical studies include the knee joint configurations, where joint architecture immutably constrains and guides movement outcomes. Investigators will default to reporting resultant joint deformation without considering the influence of joint architectural configurations on kinematic responses. The purpose of this study was to develop a new joint angular kinematic method that accounts for influence of dynamic joint architectural configuration on deformation values. Twenty subjects performed unloaded dynamic flexion/ extension and 45° cutting maneuver. The knee deformation angles obtained with the new method proposed were compared with the values that obtained using the standard method. One way repeated measurement ANOVA’s was used to compare knee deformation angles values from the standard method that uses a static trial and the new method that uses a dynamic trial. The proposed method distinguishes between dynamic joint architectural configuration and joint deformation. Loaded standard abduction/adduction (β) and rotation (γ) angles were 3.4 ±1.8° and 11.2 ±3.8°, respectively. Using the new method, the β and γ angles decrease to 1.5 ±1.4° (<0.05) and 7.1 ±1.8° (<0.05) during cutting. The new method accounted for dynamic joint architectural configuration produced loaded β and γ angles that had smaller magnitudes than the standard method, suggesting that previous studies may have overestimated β and γ angles. Injury management strategies could be influenced by a consideration for dynamic joint architectural configuration. Such a consideration could influence ligament repair strategies. Future studies should account for dynamic configuration when establishing the influence of joint deformation on graft design and appropriate isometry values during reconstruction.