Tibial bone acceleration and Ground Reaction Force parameters during running

Abstract

s-International Society of Biomechanics XII Congress 1989 1021 TIBIAL BONE ACCELERATION AND GROUND REACTION FORCE PARAMETERS DURING RUNNING Ewald M. Hennig, Mario A. Lafortune l Spottmedizinisches lnstitut Essen e.V., Universitat Essen, W-Germany Australian Institute of Sport, Canberra, Australia ’ Using data from six male subjects this study compared Ground Reaction Force and tibia1 acceleration parameters from running (4.5 m/s). A bone (tibia) mounted triaxial accelerometer, a force platform, and two LOCAM cameras were employed for data collection. Low peak values were found for the axial acceleration (5.32 g) and a time shift towards the occurence of the first peak in the vertical force data was present. The time to peak axial acceleration differed significantly from the time to the first force peak, and the peak values of force and acceleration demonstrated only a moderate correlation (r=0.76). However, a high negative correlation (r=-0.89) was obvious for the comparison of the peak axial acceleration with the time to peak vertical force. These findings indicate a substantially different behavior of tibia1 acceleration and vertical ground reaction force. A high correlation of r=0.94 was found between the peak braking force and the AP-acceleration peak. This finding may be explained by a strong muscular stabilization of the body during impact. MEASUREMENTS OF MUSCLE FIBER CONDUCTION VELOCITY AT THE M. BICEPS AND M. TRICEPS BRACHII UNDER ISOMETRIC LOAD G.O. Hering, E.M. Hennig* and H.I. Riehle Univ. Konstanz,Univ. Essen*, F.R.G. By means of the surface EMG cross-correlation technique, the muscle fiber conduction velocity (MFCV) was measured during static and dynamic isometric force development. On three different days measurements were carried out on 8 subjects at identical EMG electrode sites of the M. biceps and M. triceps. Results: 1. The MFCV at the M. triceps was significantly higher than at the M. biceps brachii in the isometric as well as in the d namic load conditions. 2. The MFCV increased with t f! e level of force production and both quantities were highly correlated (r = 0.98). 3. For both muscles significantly reduced MFCV values were found for the dynamic force development. 4. MFCV proved to be a highly reproducibel parameter. The intra-individual coefficient of variability from day to day was found to be only 6.1 % (M. biceps isom.dyn.). THREE-DIMENSIONAL GEOMETRIC ANALYSIS OF HUMAN FEMURS FOR DESIGN OF TOTAL HIP ENDOPROSTHESES Herndl G, Siebels W,* Gerhard T,* MAN Technologie GmbH, Munich, West-Germany * Institutefor Experimental Surgery, Technical University Munich, West-Germany To obtain an accurate 3-dimensional surface-model of the inner and outer shape of human femurs, 81 specimens, representatively selected, were embedded in plaster, transversely cut into slices of 3,55 mm thickness and all contours digitized resulting in a wire-frame model of the complete femur (CAD-System CATIATM). For comparison of the data and classification of the individual femurs, three out of 12 analized geometrical parameters were adequate to describe the inner surface required for implantion of cementless total hip endoprostheses.26 different groups were filled with at least one specimen. 30 % of the femurs could be collected in three main groups were again the strongest group gathered 14 % of all femurs. The design criterion was that at least 4 mn bone thickness should be left after insertion and that the kinematics for insertion is easy and does not requiretoo much extra space. The design has also taken into consideration, that the best fit is required in the medial/proximal region. The analysis for the obtainable contactarea bone/prostheses has shown that at least 70 % of the prostheses surface are serving as a real contact area.