What issue may arise from a too soft DF bumper in a TF prosthetic?

When a transfemoral (TF) prosthesis has a too soft dorsiflexion (DF) bumper, it can lead to insufficient resistance when the patient walks. This lack of firmness in the bumper may fail to provide adequate control during the initial contact and loading response phases of gait, resulting in a knee flexion moment. The knee may flex excessively at heel strike, leading to instability and increasing the risk of a fall or a loss of balance. Proper control of the knee flexion is crucial for maintaining a stable and efficient walking pattern.

While other issues like inadequate hip movement, increased socket discomfort, or extreme knee extension can relate to issues with the prosthetic fit, alignment, or suspension, the direct correlation with a too soft DF bumper particularly affects knee flexion stability during gait. Therefore, the primary concern regarding a soft DF bumper in a TF prosthetic is knee flexion resistance.