Correlation Between In Vivo Knee Contact Forces and External Measures During Gait

Researchers have sought to explain the development and progression of knee osteoarthritis using in vivo estimates of knee contact forces. Unfortunately, it is not possible to measure knee contact forces in a clinical environment. Thus, studies often estimate knee contact forces using a variety of external measures. For example, inverse dynamics knee loads such as the adduction moment and superior force are frequently used as surrogate measures of medial and total knee contact force, respectively. Contraction of muscles spanning the knee is believed to increase knee contact force, and hence muscle electromyographic (EMG) signals are another external measure that may be indicative of internal contact force. The recent development of instrumented knee implants, such as the eTibia design [1], has provided access to in vivo knee contact force data during gait and other activities. However, few studies have correlated inverse dynamics loads, and none have correlated EMG signals, with total, medial, and lateral in vivo knee contact forces.