National Physical Therapy Examination (NPTE) Practice Exam

What is the likely outcome when a transtibial prosthesis has an excessively firm heel wedge?

1. Insufficient knee flexion at loading response

2. Premature knee flexion at late midstance

3. Excessive knee flexion at loading response

4. Excessive knee flexion at late midstance

The correct answer is: Excessive knee flexion at loading response

When assessing the impact of an excessively firm heel wedge in a transtibial prosthesis, the focus should be on how it affects the timing and degree of knee flexion during the gait cycle. A firmer heel wedge provides less shock absorption and a dampened response, which can lead to altered mechanics during the loading response phase. With a firm heel wedge, as the prosthetic foot hits the ground, it does not allow for adequate compression and cushioning. This can result in increased resistance against the natural bending of the knee. Consequently, the prosthetic knee may exhibit excessive flexion as the limb absorbs the body's weight, especially during loading response. The lack of appropriate heel compression can force the knee into a more flexed position earlier in the gait cycle, leading to what is described as excessive knee flexion at this stage. Understanding this concept highlights the importance of optimizing the mechanical properties of the prosthetic components. Ensuring that the heel wedge is tailored to the individual's needs can promote a more natural gait and optimal knee motion throughout the walking cycle.