Validation of a novel biomechanical test bench for the knee joint with six degrees of freedom

Abstract

A novel biomechanical test bench has been developed for in-vitro evaluation of the knee joint. The test bench allows the kinematics of the knee joint to be studied in all six degrees of freedom. Flexion-extension knee movements are induced by quadriceps and hamstring muscle forces simulated by five pneumatic cylinders. The kinematics of the knee and the actively applied muscle forces are measured simultaneously. The aim of this study was to validate the sensitivity and reproducibility of this novel test bench. Four fresh frozen human knees were tested three times, each with seven flexion-extension cycles between 5° and 60°. After the native knees had been tested, the posterior cruciate ligament and then the lateral collateral ligament were dissected. The injured knees were tested in identical conditions [3×(7×5°-60°)] in order to evaluate whether the test bench is capable of detecting differences in knee kinematics between a native state and an injured one. With regard to reproducibility, the novel test bench showed almost perfect agreement for each specimen and for all states and flexion angles. In comparison with the native knees, the injured knees showed significant differences in knee kinematics. This validated novel test bench will make it possible to investigate various knee pathologies, as well as current and newly developed treatment options.

Modified Lemaire tenodesis reduces anterior cruciate ligament graft forces during internal tibial torque loading

“…This axis approximates the flexion–extension axis in the knee joint. It was used for standardised embedding and positioning inside the test bench [ 17 ]. The femur was cut at a distance of 150 mm and the tibia was cut at a distance of 110 mm from the inserted mediolateral pin.…”

“…Testing of the different states was conducted on a customised validated test bench with six degrees of freedom (Fig. 2 ) [ 17 ]. Moving the tibia allowed knee flexion to be adjusted to 0°, 30°, 60°, and 90° relative to the fixed femur.…”

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Fig. 2 The biomechanical knee joint test bench [ 17 ] with a knee specimen fixed at 30° of flexion. Anterior tibial translation force (red arrow) is induced by a pulley-and-weight system.

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German Society of Biomechanics (DGfB) Young Investigator Award 2019: Proof-of-Concept of a Novel Knee Joint Simulator Allowing Rapid Motions at Physiological Muscle and Ground Reaction Forces

“…Horizontal knee joint simulators are particularly characterised by the horizontal position of the knee joint specimens (Blankevoort et al, 1988; Hirokawa et al, 1991; Torzilli et al, 1994; Bach and Hull, 1995; Dürselen et al, 1995; Omori et al, 1997; Ahmad et al, 1998; Kiguchi et al, 1999; Stukenborg-Colsman et al, 2002b; Hofer et al, 2011). Typically, the femur or the tibia is fixed to the simulator base or to a moveable swing arm, which is responsible for the flexion and extension movements, whereas the opposite side provides all necessary degrees of freedom (Heinrichs et al, 2017). Robotic arm systems (Rudy et al, 1996; Livesay et al, 1997; Li et al, 1999; Lo et al, 2008; Diermann et al, 2009; Goldsmith et al, 2013) are comparable to horizontal simulators, but the knee joint is moved along a previously determined passive motion path in which all external forces and moments acting on the knee joint are minimal (Lorenz et al, 2013).…”

“…This is realised by weights or actuators and steel cables, which are connected to the bone at the anatomical insertion sites or directly to the muscles by special clamps. Typically, the quadriceps muscle, the two-headed gastrocnemius muscle or the hamstring muscles are simulated (Hirokawa et al, 1991; Shoemaker et al, 1993; Bach and Hull, 1995; Dürselen et al, 1995; Ahmad et al, 1998; Li et al, 2002; Gill et al, 2003; Hofer et al, 2011; Heinrichs et al, 2017). However, in most cases the applied muscle forces are relatively low and attain only values of up to 200 N (e.g., simulating the quadriceps muscle; Dürselen et al, 1995; Withrow et al, 2006).…”