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Triaxial force transducer for investigating stresses at the stump/socket interface
R B Williams1, D Porter, V C Roberts
1Department of Medical Engineering & Physics, King's College School of Medicine, London, UK.
Medical & Biological Engineering & Computing
|January 1, 1992
Summary
Investigating shear and normal stresses at the prosthetic socket interface is crucial for amputee comfort. A new miniature transducer measures these stresses, revealing differences in prosthetic feet that impact fit and potentially reduce tissue damage.
Area of Science:
- Biomechanics
- Biomedical Engineering
- Prosthetics and Orthotics
Background:
- Normal pressures at the lower-limb amputee stump socket interface are understood, but shear stresses are not.
- Combined shear and normal stresses can worsen discomfort and cause tissue damage.
- Accurate measurement of both stress types is needed to improve prosthetic fit.
Purpose of the Study:
- To develop a method for simultaneously measuring normal and shear stresses at the stump socket interface.
- To investigate the interface stress variations during the gait cycle.
- To compare stress patterns between different prosthetic feet.
Main Methods:
- Development of a miniature triaxial force transducer (4.9 x 16 mm diameter) for socket integration.
- Description of the transducer's operating principle, construction, performance, and limitations.
- Preliminary measurement of interface stresses in a supra-condylar PTB socket during gait.
Main Results:
- The developed miniature triaxial force transducer successfully measured interface stresses.
- Preliminary data revealed variations in stress patterns over the gait cycle.
- Distinct differences in stress patterns were observed between two tested prosthetic feet.
Conclusions:
- A novel miniature transducer enables simultaneous measurement of normal and shear stresses at the prosthetic socket interface.
- Interface stress patterns vary during gait and are influenced by prosthetic foot selection.
- This technology can aid in optimizing prosthetic fit and reducing patient discomfort and tissue damage.