Quantification of Shear Stresses Within a Transtibial Prosthetic Socket

Area of Science:

• Biomechanics
• Prosthetics
• Rehabilitation Engineering

Background:

• Limited objective data exists on weightbearing distribution in transtibial prosthetic sockets.
• Current understanding relies heavily on finite element analysis (FEA) computer models.

Purpose of the Study:

• To objectively measure weightbearing distribution within prosthetic sockets for transtibial amputees.
• To validate a clinical model for assessing prosthetic socket loading patterns.

Main Methods:

• Four high-functioning transtibial amputees were fitted with custom prosthetic sockets containing three load cells.
• Dynamic loading was recorded during sit-to-stand, step-off, and walking initiation.
• Anterior/posterior shear, superior/inferior shear, and end weightbearing forces were measured.

Main Results:

• Consistent load patterns were observed across all four subjects during the tested functional activities.
• Negligible load transmission occurred at the distal end of the residual limbs.
• High correlation coefficients (.82–.98) indicated linear relationships in loading among subjects.

Conclusions:

• The experimental model accurately recorded transtibial prosthetic socket loading, aligning with FEA predictions.
• This clinical model enables objective measurement and comparison of weightbearing in different prosthetic socket designs.