JOINTS - NATURE'S HIGH-TECH? - Biomechanical Methods, Instruments and Models for the Analysis of Load and Strain Imposed on Human Joints by Participation in Sport Activities

Abstract

Are joints nature's high-tech development? Are they anatomical marvels moved and steadied by muscles, cartilage and tendons, incomparable in their precision and durability? Or are they - due to a phylogenetic development from quadrupedal to bipedal locomotion - rather more to be viewed as faulty constructions whose complicated mechanisms are highly injury-prone and whose structures fairly rapidly begin to show signs of war and tear caused by the stress of everyday usage or sport activities? In this contribution the dynamic aspects of the functional anatomy of the large joints (shoulder, elbow, hand, hip, knee and ankle, as well as the vertebral column) are briefly presented, along with an overview of biomechanical methods, instruments and models for the analysis of loads and strains imposed on human joints by participation in sports. Special methods for the calculation of the forces and torques of human joints were developed using SDS software (Solid Dynamic System. France) employing 39 anthropometric measurements of each athlete. These were processed using the program ANT, which we developed for general use. ANT calculates the 15 segments of the Hanavan model by using the mass density given by Dempster et al. (1967), whereby X-ray-kinematographic and magnetic-resonance tomographic studies of the knee joint (15 subjects in vivo, 3 joints in vitro), ankle joint (20 subjects in vivo) and vertebral column (5 subjects in vivo) supplemented the model parameter for anthropometry. As examples analyses of trampoline gymnasts (see graphics) and runners are presented, carried out with the assistance of the 30 Peak Performance System and supplemented by measurements made using Kistler measurement platforms and the Novel- Pedar System (pressure distribution). Clinical and X-ray-genological long-term studies of the vertebral columns of trampoline gymnasts, along with comparative studies by other authors, provide a concluding overview of the effects of strain on human joints.