Robotic knee laxity testing: Reliability and normative data

Purpose: To evaluate the reliability of the GeNouRoB knee arthrometer and present normative values of knee anterior laxity using this device on young females. Methods: Anterior laxity in both knees was tested in two groups of young, uninjured females using the hamstrings electromyography biofeedback feature of the device. There were 13 participants in the group tested for reliability and 23 for the normative study. Laxity (mm of movement of the proximal tibia in the anterior direction relative to the femur) was calculated at test forces of 134. N and 250. N with values presented for the unstandardised and standardised (relative to stabilisation force) conditions. Results: The relative reliability (95% limits of agreement) of the device for laxity at a test force of 134. N was 2 to 3. mm. Left knee anterior laxity was almost 1. mm greater than the right. Conclusions: The relative reliability of the GeNouRoB arthrometer is comparable to the KT device. In agreement with previous work on the nonrobotic KT arthrometer, the knee anterior laxity values found with the GeNouRoB are greater in the left as compared to the right knee.