Functional evaluation of the TKA patient using the coordination and variability of rising.
A kinematic analysis of the knee function is important for the evaluation of total knee arthroplasties (TKA). We used the coordination and variability of rising from a chair as functional knee parameters. Twelve knee patients were measured prior to surgery (=pre-TKA group) and one year after surgery (=post-TKA group). A group of 15 healthy, age-matched subjects was selected as control group. The WOMAC questionnaire, frequently used by orthopaedic surgeons, was administered prior to the test. The test consisted of 10 times rising from a low chair and 10 times from a high chair. Knee and hip angles and angular velocities were measured with electrogoniometers. The relative phase (=MRP) between hip and knee was a measure for the coordination of rising and the standard deviation of the relative phase of the 10 trials (=SRP) was a measure for the variability. The coordination and variability of rising of the TKA patients were compared to the control group, and the relationship with the WOMAC questionnaire was calculated. The coordination of rising from a high chair and the variability of rising from both chair heights were significantly different for the pre-TKA group compared to the control group (p<0.05). The post-TKA group showed no significant differences with the control group, which indicates a functional recovery after TKA implantation. The functional parameters correlated adequately with the subjective WOMAC questionnaire. This study showed that our method is an objective measure of functionality and it will be worthwhile to use it as an additional evaluation tool.