A finite element model to assess transtibial prosthetic sockets with elastomeric liners

Area of Science:

• Biomechanics
• Biomedical Engineering
• Prosthetics and Orthotics

Background:

• Transtibial amputation often leads to residual limb skin breakdown.
• High pressures and shear stresses at the limb-socket interface are primary causes.
• Understanding these interface mechanics is crucial for prosthetic design.

Purpose of the Study:

• To develop a finite element model (FEM) of a transtibial prosthesis.
• To analyze stress and pressure distributions at the residual limb-socket interface.
• To identify critical areas prone to skin breakdown.

Main Methods:

• Created transtibial FEMs using MRI scans of three distinct residual limb shapes.
• Incorporated socket geometry, frictional interactions, and an elastomeric liner.
• Evaluated models under two loading profiles simulating the stance phase.

Main Results:

• Identified five specific locations of peak stress on residual limbs.
• These peak stress locations corresponded to previously reported sites of skin breakdown.
• Peak contact pressure reached 98 kPa and maximum shear stress reached 50 kPa.

Conclusions:

• The developed FEM accurately predicts high-stress areas linked to skin breakdown.
• This model can inform the design of prosthetic sockets to mitigate mechanical stress.
• Future work can explore material properties and limb volume changes using this FEM.