MICHAUD, F. | bioRxiv Science

bioRxiv2024

A SENSORIZED 3D-PRINTED KNEE TEST RIG FOR EXPERIMENTAL VALIDATION OF PATELLAR TRACKING AND CONTACT SIMULATION AFTER TOTAL KNEE REPLACEMENT

Total knee arthroplasty aims to relieve pain and restore function in the affected joint through artificial implants. Despite advances in design and surgical techniques, there are complications associated with surgery, especially concerning the patella. The use of musculoskeletal models in orthopedic surgery allows for objective prediction of postoperative function and optimization of results for each patient. To ensure that simulations are trustworthy and can be used for predictive purposes, comparing simulation results with experimental data is crucial. Although progress has been made in obtaining 3D bone geometry and estimating contact forces, validation of these predictions has been limited due to the lack of direct in vivo measurements and the economic and ethical constraints associated with available alternatives. In this study, an existing commercial surgical training station was transformed into a sensorized test bench. The use of 3D-printed models and sensors allowed low-cost and reproducible experimental validation of computer simulation (patellar movement and forces) while avoiding ethical issues.

bioengineering↗

bioRxiv2019

DO MUSCLE SYNERGIES IMPROVE OPTIMIZATION PREDICTION OF MUSCLE ACTIVATIONS DURING GAIT?

Determination of muscle forces during motion can help to understand motor control, assess pathological movement, diagnose neuromuscular disorders, or estimate joint loads. Difficulty of in vivo measurement made computational analysis become a common alternative in which, as several muscles serve each degree of freedom, the muscle redundancy problem must be solved. Unlike static optimization (SO), synergy optimization (SynO) couples muscle activations across all time frames, thereby altering estimated muscle co-contraction. This study explores whether the use of a muscle synergy structure within a static optimization framework improves prediction of muscle activations during walking. A motion/force/EMG gait analysis was performed on five healthy subjects. A musculoskeletal model of the right leg actuated by 43 Hill-type muscles was scaled to each subject and used to calculate joint moments, muscle-tendon kinematics and moment arms. Muscle activations were then estimated using SynO with two to six synergies and traditional SO, and these estimates were compared with EMG measurements. SynO neither improved SO prediction of experimental activation patterns nor provided SO exact matching of joint moments. Finally, synergy analysis was performed on SO estimated activations, being found that the reconstructed activations produced poor matching of experimental activations and joint moments. As conclusion, it can be said that, although SynO did not improve prediction of muscle activations during gait, its reduced dimensional control space could be beneficial for applications such as functional electrical stimulation (FES) or motion control and prediction.

neuroscience↗