Abstract
Knee mechanics - Knee forces during ADL and sports activities in TKA patients
Background
Tibiofemoral forces are important in the design and clinical outcomes of TKA. Knee forces and kinematics have been estimated using computer models or traditionally have been measured under laboratory conditions. Although this approach is useful for quantitative measurements and experimental studies, the extrapolation of results to clinical conditions may not always be valid. We therefore developed a tibial tray combining force transducers and a telemetry system to directly measure tibiofemoral compressive forces in vivo.
Methods
Tibial forces were measured for activities of daily living, athletic and recreational activities, and with orthotics and braces, for 4 years postoperatively. Additional measurements included video motion analysis, EMG, fluoroscopic kinematic analysis, and ground reaction force measurement. A third-generation system was developed for continuous monitoring of knee forces and kinematics and for classifying and identifying unsupervised activities outside the laboratory using a wearable data acquisition hardware.
Results
Peak forces measured for the following activities were: walking (2.6±0.2xBW); jogging (4.2±0.2)xBW; stationary bicycling (1.3±0.15)xBW; golfing (4.4±0.1)xBW; tennis (4.3±0.4)xBW; skiing (4.3±0.1)xBW; hiking(3.2±0.3)xBW; StairMaster exercise (3.3±0.3)xBW; Elliptical machine exercise (2.3±0.2)xBW; leg press machine (2.8±0.1)xBW; knee extension machine (1.5±0.03)xBW, rowing machine (0.9±0.1)xBW.
Conclusions
In vivo measured knee forces can be used to enhance existing in vitro models and wear simulators and to improve prosthetic designs and biomaterials as well as guide physicians in their recommendations to patients of “safe” activities following TKA.
