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Biomedical subjects

N Berme

Publications and source records attributed to N Berme.

31 records · Page 2Linked to original sources
PubMed1988

The dynamics of quadrupedal locomotion.

This paper presents a dynamical analysis of quadrupedal locomotion, with specific reference to an adult Nubian goat. Measurements of ground reaction forces and limb motion are used to assess variations in intersegmental forces, joint moments, and instantaneous power for three discernible gaits: walking, running, and jumping. In each case, inertial effects of the torso are shown to dominate to the extent that lower-extremity contributions may be considered negligible. Footforces generated by the forelimbs exceed those exerted by the hindlimbs; and, in general, ground reactions increase with speed. The shoulder and hip dominate mechanical energy production during walking, while the knee plays a more significant role in running. In both cases, however, the elbow absorbs energy, and by so doing functions primarily as a damping (control) element. As opposed to either walking or running, jumping requires total horizontal retardation of the body's center of mass. In this instance, generating the necessary vertical thrust amounts to energy absorption at all joints of the lower extremities.

Animals↗
PubMed1987

Femoral cement removal in revision total hip arthroplasty. A biomechanical analysis.

A technique of femoral cement removal in revision total hip arthroplasty is described and biomechanically evaluated. Two 9-mm holes are drilled anteriorly through the proximal femoral cortex before cement is removed. These holes permit direct visualization of the medullary canal and help to prevent eccentric reaming or inadvertent perforation with the power drill. They also provide portals for enhanced irrigation, illumination, and cement removal. For assessment of the effect of cortical perforations on bone strength, 12 cadaveric femurs containing cemented prosthetic stems were analyzed. The femurs were stressed at various loads on the Instron Materials Testing Machine (Instro Engineering Corporation, Kenton, MA) under conditions simulating single-limb stance. The stress concentrations were significantly higher about laterally drilled holes than about those located anteriorly. When loaded to failure, all fractures occurred at or below the prosthetic stem tip. No fractures occurred in the proximally placed drill holes. A finite element model showed that two holes kept at least two hole diameters apart did not cause cumulative stress concentration.

Biomechanical Phenomena↗
PubMed1984

Kinematic and force data collection in biomechanics by means of sonic emitters--I: Kinematic data collection methodology.

In this paper, first, the principles of sonic digitizing are presented. Next, a description of quantitative determination of the relative motion between two body segments by utilization of sonic emitters is provided. A new kinematic data collection methodology and data analysis is proposed to check continuously the accuracy of the data collected by means of the sonic emitters. The first part of the paper is terminated by establishment of an accuracy criteria and selection of the most accurate data set and associated error analysis. Quantitative results based upon the kinematic data collection methodology of Part I were obtained for the forced kinematic motion of the human shoulder complex and are presented in Part II.

Arm↗
PubMed1984

Kinematic and force data collection in biomechanics by means of sonic emitters--II: Force data collection and application to the human shoulder complex.

In multisegmented mathematical models of the human body the most difficult and the least successful modeling of a major articulating joint has been the shoulder complex because of the lack of appropriate biomechanical data as well as the anatomical complexity of the region. In this paper, quantitative results on the variability of the stiffness of the shoulder complex dependent upon orientation of the upper arm are presented by applying the principles and theory developed in Part I. The paper starts with a description of a multiple-axis force and moment transducer and its utilization with sonic emitters in determining direction as well as location of the general force and moment vectors applied on a body segment. The numerical results which are presented for three subjects are in the form of plots showing the passive resistance of the shoulder complex as functions of drawer displacements of the upper arm along its long bone axis. Exponential and power curve fitting of the numerical results are also provided to establish intra-subject variations and similarities of the behavioral patterns of the axial stiffness characteristics of the human shoulder complex.

Arm↗
PubMed1980

Resultant finger joint loads in selected activities.

The intersegmental loads transmitted by the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints of the index finger are presented in activities involving application of a twisting moment by the hand. Twenty normal subjects, ten males and ten females were included in the studies. A six component load transducer was incorporated in each of the two fixtures representing a water tap and a jar cap 70mm in diameter and the maximal loading on the fingers was monitered in applying an isometric twisting moment to these structures. Two different hand configurations were studied for each activity: the spatial position and orientation of the finger segments were determined using two orthogonally positioned still cameras, and specially designed stick markers were utilized to highlight anatomical landmarks. The results confirm the use of the finger in a complex three-dimensional manner with no significant differences between the male and female subjects. Forces recorded in the jar cap activity were larger than those applied in the tap activity, the maximum being around 100 N and in general the abduction/adduction moments developed at both joints were of comparable magnitude to flexion/extension. Torques as high as 0.6 Nm and 1.0 Nm were calculated at the PIP and MCP joints respectively.

Adult↗
PubMed1979

Load actions transmitted by implants.

The authors consider the mechanics of load transmission between a "conventional" femoral head replacement prosthesis and the shaft of the femur. The three dimensional loading pattern is now well known and the changes of interface stressing through a load cycle is considered. The actual stress situation depends on features of the implantation technique, the mechanical properties of all the materials involved in the relevant friction coefficient. From analysis of systems at the extreames of these limits, the authors suggest probable service conditions.

Femur↗
PubMed1978

Measurement of prosthetic alignment.

An essential part of alignment description is the position and orientation of the socket relative to the rest of the limb. Repeatable measurements of these parameters is hindered by the non-geometrical shape of the socket. A unique axis system has already been defined to enable such measurements to be carried out. The method however, employs an iterative technique and is time consuming. A simple device to facilitate these measurements has been developed and is reported.

Amputation Stumps↗
PubMedDate not supplied

Measurement of angular displacements using Hall effect transducers.

Hall effect transducers were studied as an alternative to limited-wear precision potentiometers and optical encoders in measuring angular displacements. Various design parameters are identified, and the optimum Hall effect transducer configuration is presented. Using this configuration, it was possible to measure an angular rotation of 140 degrees with a standard deviation of 0.5 degrees. Within the +/- 35 degrees mid-range of the total 140 degrees, the standard deviation improved to 0.1 degrees.

Biomechanical Phenomena↗