Whiteboard Cleaning Task Realization with HOAP-2

The controller has a motion feedback control loop for the four arm joints and a force feedback control loop for the ankle joint. The desired motion/force trajectories are obtained via kinesthetic teaching by a human, followed by a learning phase. During skill demonstration, the arm joints are made compliant while the robot balances using ankle/hip strategies. Experimental data demonstrate the feasibility of the method

Biomechanical considerations in the pathogenesis of osteoarthritis of the knee

Osteoarthritis is the most common joint disease and a major cause of disability. The knee is the large joint most affected. While chronological age is the single most important risk factor of osteoarthritis, the pathogenesis of knee osteoarthritis in the young patient is predominantly related to an unfavorable biomechanical environment at the joint. This results in mechanical demand that exceeds the ability of a joint to repair and maintain itself, predisposing the articular cartilage to premature degeneration. This review examines the available basic science, preclinical and clinical evidence regarding several such unfavorable biomechanical conditions about the knee: malalignment, loss of meniscal tissue, cartilage defects and joint instability or laxity

The computer-assisted sequential lateral soft-tissue release in total knee arthroplasty for valgus knees

Soft-tissue management is a critical factor in total knee arthroplasty, especially in valgus knees. The stepwise release has been based upon surgeon’s experience. Computer-assisted surgery has gained increasing scientific interest in recent times and allows the intraoperative measurement of leg axis and gap size in extension and flexion. We therefore aimed to analyse the effect of sequential lateral soft-tissue release and the resulting change in the a.p. limb axis on the one hand and the tibiofemoral gaps on the other hand in extension as well as in flexion in eight cadaveric knees. Measurements were obtained using a CT-free navigation system. In extension the highest increase compared to the previous release step was found for the first (iliotibial band, P = 0.002), second (popliteus muscle, P = 0.0003), third (LCL, 0.007) and the sixth (entire PCL, P = 0.001) release step. In 90° flexion all differences of the lateral release steps were statistically significant (P < 0.004). Massive progression of the lateral gap in flexion was found after the second (popliteus muscle, P = 0.004) and third (LCL, 0.007) release step. Computer-assisted surgery allows measurement of the effect of each release step of the sequential lateral release sequence and helps the surgeon to better assess the result

Preoperative laxity in osteoarthritis patients undergoing total knee arthroplasty

A preoperative quantitative evaluation of soft tissues is helpful for planning total knee arthroplasty, in addition to the conventional clinical examinations involved in moving the knee manually. We evaluated preoperative coronal laxity with osteoarthritis in patients undergoing total knee arthroplasty by applying a force of 150 N with an arthrometer. We examined a consecutive series of 120 knees in 102 patients. The median laxity was 0° in abduction and 8° in adduction. The femorotibial angle on non-weight-bearing standard anteroposterior radiographs was 180° and correlated with both abduction (r = −0.244, p = 0.007) and adduction (r = 0.205, p = 0.025) laxity. The results of a regression analysis suggested that the femorotibial angle is helpful for estimating both laxities. Considering the many reports on how to obtain well-balanced soft tissues, stress radiographs might help to improve the preoperative planning for gaining the optimal laxity deemed appropriate by surgeons