Intervertebral reaction force prediction using an enhanced assembly of OpenSim models

Abstract

OpenSim offers a valuable approach to investigating otherwise difficult to assess yet important biomechanical parameters such as joint reaction forces. Although the range of available models in the public repository is continually increasing, there currently exists no OpenSim model for the computation of intervertebral joint reactions during flexion and lifting tasks. The current work combines and improves elements of existing models to develop an enhanced model of the upper body and lumbar spine. Models of the upper body with extremities, neck and head were combined with an improved version of a lumbar spine from the model repository. Translational motion was enabled for each lumbar vertebrae with six controllable degrees of freedom. Motion segment stiffness was implemented at lumbar levels and mass properties were assigned throughout the model. Moreover, body coordinate frames of the spine were modified to allow straightforward variation of sagittal alignment and to simplify interpretation of results. Evaluation of model predictions for level L1-L2, L3-L4 and L4-L5 in various postures of forward flexion and moderate lifting (8 kg) revealed an agreement within 10% to experimental studies and model-based computational analyses. However, in an extended posture or during lifting of heavier loads (20 kg), computed joint reactions differed substantially from reported in vivo measures using instrumented implants. We conclude that agreement between the model and available experimental data was good in view of limitations of both the model and the validation datasets. The presented model is useful in that it permits computation of realistic lumbar spine joint reaction forces during flexion and moderate lifting tasks. The model and corresponding documentation are now available in the online OpenSim repository.

Fusion angle affects intervertebral adjacent spinal segment joint forces—Model‐based analysis of patient specific alignment

“…For the range of motions (ROM) investigated in the present study, the predictive performance of the base model for normalized and absolute compressive joint forces was within an accuracy of 10% compared to reported in vivo intradiscal pressure measurements and biomechanical model predictions. The force development during simulated dynamic movement (forward–backward flexion) could furthermore be predicted with good agreement to measured in vivo implant loads …”

“…Bushing elements placed in each joint mimic overall rotational joint stiffnesses as expected from passive elements such as discs and ligaments. The calibration of bushing and details about joint implementation can be found in a separate publication on the musculoskeletal model …”

Cervical Spine Injuries: A Whole-Body Musculoskeletal Model for the Analysis of Spinal Loading

“…Further modelling developments will include the replacement of neck kinematic constraints with contact models [28, 83] and the inclusion of EMG driven simulations [84] for the estimation of muscle forces. Future application of the models will firstly include the simulation of injurious events, and the analysis of neck muscle contribution to cervical spine loading during rugby activities, such as scrummaging and tackling.…”

Apportionment of lumbar L2–S1 rotation across individual motion segments during a dynamic lifting task

“…If true, this would further imply that, deploying a pelvic restraint, as done by Harada et al and others (Okawa et al, 1998;Teyhen et al, 2007;Wu et al, 2014), might not significantly alter lumbar motion profiles, although it obviously precludes an accounting of the pelvic contribution, which, as Tafazzol et al have shown, can be significant. The flexed spine also experiences the largest compressive forces compared to other postures (Anderson et al, 1986;Han et al, 2012;Schultz et al, 1982;Senteler et al, 2015;Tafazzol et al, 2014;Wilke et al, 1999). Overloading has particularly been shown to be a prominent biomechanical risk factor for L5-S1 disk disorders (Waters et al, 1993).…”

“…In both cases, an accurate description of dynamic, threedimensional (3D) vertebral kinematics is necessary (Waters et al, 1993). This is because (a) normal functional motion benchmarks are mainly based on kinematic measures, and (b) given the infeasibility of direct measurement, in vivo forces experienced by lumbar tissue structures are estimated from biomechanical models (Cholewicki et al, 1991;de Zee et al, 2007;Han et al, 2012;Senteler et al, 2015;Stokes and Gardner-Morse, 1995;Waters et al, 1993;Zhu et al, 2013), the process of which is highly sensitive to the quality of kinematic input.…”