Article

The term 'sock ply' may be a source of confusion in prosthetics
practice because there may not be a consistent relationship between sock ply and sock thickness.
The purpose of this study was to characterize how
sock ply related to sock thickness for different sock materials commonly used in
limb prosthetics. We also evaluated how sock thickness changed under loading
conditions experienced while wearing a lower limb prosthesis compared with
unstressed conditions. STUDY DESIGN: Experimental. Mechanical assessment.
METHODS: Seven sock materials of varying ply and sheaths were tested using a
custom instrument. Sock thickness under eight different compressive stress
conditions and two different biaxial in-plane tensile strain conditions were
measured. RESULTS: For socks woven from a single material, thickness under
walking stance phase conditions averaged 0.7, 1.2 and 1.5 mm for 1, 3 and 5-ply,
respectively. For socks woven from several materials, the corresponding results
were 0.4, 0.7 and 0.8 mm, respectively. Sock ply did not sum, e.g. a 3-ply sock
was not three times the thickness of a 1-ply sock. CONCLUSIONS: Sock thickness
and compressive stiffness are strongly dependent upon sock material, interface
pressure, and in-plane biaxial strain.

Langue : ANGLAIS