Hip joint contact forces in normal subjects and subjects with total hip prostheses: walking and stair and ramp negotiation.
OBJECTIVE
To calculate the hip joint contact force in normal subjects and subjects with total hip replacements.


METHODS
An observational study of age matched normal subjects and subjects with hip joint replacements.


BACKGROUND
Hip joint contact forces have been calculated using musculo-skeletal models and measured in vivo using instrumented hip prostheses. There are few examples of studies performed on subjects in the 40-60 year age range. This study characterises the forces in both normal subjects and subjects with hip joint replacements for these 'young' subjects.


METHODS
Motion analysis and force plate data were used as input to a three-dimensional model of the leg. Five male and six female normal subjects and five male subjects with hip prostheses were studied. Each subject was observed walking and negotiating stairs and a ramp.


RESULTS
Hip joint contact forces in both thigh and pelvic-based co-ordinate systems are presented. Subjects cadence, speed and stride length are given.


CONCLUSIONS
In general subjects with hip replacements exhibited lower hip joint contact forces than age matched normal subjects. It is suggested that this was the results of the lower speeds, stride lengths and cadences adopted by the subjects with hip replacements.


CONCLUSIONS
The characterisation of hip joint contact forces provides essential information for prosthetic joint design and testing. The comparison of hip joint contact forces in normal subjects with those in subjects with prosthetic joints provides evidence of, not only actual use of joints, but also of possible levels of force that might be applied to hip prostheses if subjects returned to normal use.
Stansfield
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BW
Bioengineering Unit, University of Strathclyde, Wolfson Centre, 106 Rottonrow, Glasgow, G4 0NW, Scotland, UK. benedict.stansfield@strath.ac.uk
Nicol
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AC
D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D016138:Walking / Q000502:physiology*