Research Article: Joint axes of rotation and body segment parameters of pig limbs

Date Published: September 6, 2007

Publisher: BioMed Central

Author(s): Vivi M Thorup, Frede Aa Tøgersen, Bente Jørgensen, Bente R Jensen.


To enable a quantification of net joint moments and joint reaction forces, indicators of joint loading, this study aimed to locate the mediolateral joint axes of rotation and establish the body segment parameters of the limbs of pigs (Sus scrofa). To locate the joint axes of rotation the scapulohumeral, humeroradial, carpal complex, metacarpophalangeal, coxofemoral, femorotibial, tarsal, and metatarsophalangeal joints from 12 carcasses were studied. The joints were photographed in three positions, bisecting lines drawn at fixed landmarks with their intersection marking the joint axes of rotation. The body segment parameters, i.e. the segment mass, center of mass and moment of inertia were measured on the humerus, radius/ulna, metacarpus, forepastern, foretoe, femur, tibia, metatarsus, hindpastern, and hindtoe segments from five carcasses. The segments were weighed, and their center of mass was found by balancing them. The moments of inertia of the humerus, radius/ulna, femur and tibia were found by rotating the segments. The moments of inertia of the remaining segments were calculated. Generally, the joint axes of rotation were near the attachment site of the lateral collateral ligaments. The forelimb, with segments taken as one, was significantly lighter and shorter than the hindlimb (P < 0.001). In all segments the center of mass was located 31 to 50% distal to the proximal segment end. The segment mass decreased with distance from the trunk, as did the segment moment of inertia. The results may serve as reference on the location of the joint axes of rotation and on the body segment parameters for inverse dynamic modeling of pigs.

Partial Text

Net joint moments and joint reaction forces can be quantified using inverse dynamic modeling [1,2], provided that knowledge of the body segment parameters (BSPs) and the locations of the joint axes of rotation (JARs) exists. BSPs are required as input for the inverse dynamic model, and JARs define the boundaries of the model segments. To the best of our knowledge neither BSPs nor JARs have been studied in pigs, therefore this study aimed to locate the mediolateral JARs and establish the BSPs of segments from fore- and hindlimbs of healthy pigs.

The author(s) declare that they have no competing interests.

VMT participated in the study design, carried out the experiments and drafted the manuscript. FAT calculated the JAR locations. BJ and BRJ designed the experiments and helped drafting the manuscript. All authors read and approved the final manuscript.




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