Novel Synthetic Biolubricant Reduces Friction in Previously-Worn Cartilage Evaluated by Long-Duration Torsional Friction Test

During osteoarthritis (OA), the lubricity of synovial fluid (SF) decreases. Therefore, we synthesized a novel, 2MDa polymer biolubricant (“2M TEG”) designed to augment the lubricating properties of SF in OA. This study’s aims were 1) to compare the abilities of 2M TEG and bovine synovial fluid (BSF) to reduce the coefficient of friction (COF) for previously “worn” cartilage specimens during a long-duration, torsional, wear test, and 2) using the same regimen, examine the “reversibility” of 2M TEG’s lubricity relative to BSF. For both aims, each wear test consisted of subjecting mated, bovine osteochondral plug pairs to 10,080 rotations. To accomplish Aim 1, plug pairs were subjected to three sequential wear regimens (Wear 1-3). Wear 1&2 were used to progressively “wear” the cartilage, and Wear 3 was used to test the efficacy of either BSF (n=4) or 2M TEG (n=4) on “worn” cartilage. For Aim 2, three pairs were subjected to four sequential wear regimens, where the lubricants were BSF, BSF, 2M TEG, and BSF, respectively. The relative percent reduction in COF between Wear 3 and Wear 2 in Aim 1 was greatest for 2M TEG, followed by BSF. For Aim 2, the mean percent reduction in COF for Wear 3 relative to Wear 2 was almost exactly the same as the mean increase in COF for Wear 4 relative to Wear 3. By reducing the COF for worn cartilage in OA joints, synthetic biolubricants such as 2M TEG could help minimize further cartilage wear and ameliorate the progression of OA.
Listed In: Biomechanical Engineering, Biomechanics, Biotribology, Orthopedic Research

Are static and dynamic squatting activities comparable?

Background: Numerous studies have described 3D kinematics, 3D kinetics and electromyography (EMG) of the lower limb during quasi-static or dynamic squatting activities. However there is only little information on the comparison of these two squatting conditions. Only one study compared these activities in terms of 3D kinematics, but no information was available on 3D kinetics and EMG. The purpose of this study was to compare simultaneous recordings of 3D kinematics, 3D kinetics and EMG of the lower limb during quasi-static and fast dynamic squats. Methods: Ten subjects were recruited. 3D knee kinematics was recorded with a motion capture system, 3D kinetics was recorded with a force plate, and EMG of 8 muscles was recorded with surface electrodes. Each subject performed a quasi-static squat and several fast dynamic squats from 0° to 70° of knee flexion. Findings: Mean differences between quasi-static and dynamic squats were 1.6° for rotations, 1.8 mm for translations, 38 N ground reaction forces (2.1 % of subjects’ body weight), 6 Nm for torques, 13.0 mm for center of pressure, and 7 µV for EMG (6.3% of the maximum dynamic electromyographic activities ). Some significant differences (P < 0.05) were found in anterior-posterior translation, vertical forces and EMG. Interpretation: All differences found between quasi-static and fast dynamic squats can be considered small. 69.5% of the compared data were equivalent. In conclusion, this study show for the first time that quasi-static and dynamic squatting activities are comparable in terms of 3D kinematics, 3D kinetics and EMG.

Listed In: Biomechanical Engineering, Biomechanics, Gait, Orthopedic Research, Posturography