A Probabilistic Model of Glenohumeral External Rotation Strength for Healthy Normals and Rotator Cuff Tear Cases

The reigning paradigm of musculoskeletal modeling is to construct deterministic models from parameters of an “average” subject and make predictions for muscle forces and joint torques with this model. This approach is limited because it does not perform well for outliers, and it does not model the effects of population parameter variability. The purpose of this study was to simulate variability in musculoskeletal parameters on glenohumeral external rotation strength in healthy normals, and in rotator cuff tear case using a Monte Carlo model. The goal was to determine if variability in musculoskeletal parameters could quantifiably explain variability in glenohumeral external rotation strength. Multivariate Gamma distributions for musculoskeletal architecture and moment arm were constructed from empirical data. Gamma distributions of measured joint strength were constructed. Parameters were sampled from the distributions and input to the model to predict muscle forces and joint torques. The model predicted measured joint torques for healthy normals, subjects with supraspinatus tears, and subjects with infraspinatus–supraspinatus tears with small error. Muscle forces for the three conditions were predicted and compared. Variability in measured torques can be explained by differences in parameter variability.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44005/1/10439_2005_Article_9045.pd

A Biomechanical Musculoskeletal Model of Human Upper Limb for Dynamic Simulation

. In this paper, we provide the biomechanical model of human upper limb we have designed and applied to the three-dimensional left human arm reconstructed from the Visible Human imaging Dataset. This model includes the mechanical properties for bones, joints and muscles lines of action. This work has been done as a part of the European Esprit Project CHARM. Its objective is to develop a Comprehensive Human Animation Resource Model allowing the dynamic simulation of complex musculoskeletal systems, including finite element deformation of soft-tissues and muscular contraction. In our approach, simplifications have been done so as to ensure the feasibility of the project while preserving the biomechanical validity of the model. Animations: http://ligwww.epfl.ch/~maurel/EGCAS96.html 1 Introduction The European Esprit Project CHARM involving several universities proposes the development of a comprehensive human resource data base, allowing the dynamic simulation of complex muscu..