Higher knee hypertension in patients with hemiplegia correlates lower lateral and medial meniscus volume in the paretic leg

Stroke is a disease with high morbidity and disability rate. After stroke, slower walking velocity, shorter step length, higher cadence, larger step width, and longer stance phase duration can be apparently observed. Additionally, these abnormal gait parameters eventually lead to knee hyperextension, known as genu recurvatum. Walking with such knee hyperextension usually induces knee pain and joint lesions, leading to cumulative damage and degenerative changes and further decreasing the standing phases stability. However, do higher angles of knee hyperextension have any correlation between the gait parameters, the kinematics, the kinetic parameters, the meniscus volume, and the water content of meniscus in paretic and non-paretic legs? This study attempted to answer these questions. The results revealed that 1) longer time since hemiplegia led to larger angles of knee hyperextension, 2) larger angles of knee hyperextension led to more tears in medial/lateral meniscus, and 3) larger angles of knee hyperextension decreased water content of the lateral meniscus in the non-paretic leg but increased water content of the medial meniscus. This was the first study to demonstrate these three above-mentioned observations through magnetic resonance imaging and motion capture system. These results suggested that 1) the knee hyperextension needed to be diagnosed and treated as early as possible; 2) the time since hemiplegia could be an indicator of sign of knee hyperextension; and 3) it might be not effective to identify the knee hyperextension by using spatial-temporal gait parameters.