What is a likely cause for a socket appearing to drop away from the residual limb in TT prostheses during preswing?

In the context of transfemoral (TT) prostheses during the preswing phase, when the socket appears to drop away from the residual limb, a likely cause is that the socket is too loose. A loose socket can fail to maintain adequate contact with the residual limb, leading to movement that creates a sense of separation between the limb and the prosthetic socket.

During the preswing phase of gait, the residual limb undergoes a change in position as the weight shifts and the knee begins to flex in preparation for the swing phase. If the socket is not snugly fit, this movement can cause a lack of stability and control, allowing the socket to move away from the residual limb instead of maintaining contact. This off-fit can impact the individual's ability to walk efficiently and may also lead to skin issues due to excess movement or friction.

While factors such as tight suspension, incorrect foot placement, or misconfigured socket alignment can all contribute to gait abnormalities, they do not directly result in the socket appearing to drop away in the same manner as a loose socket. The most direct and immediate cause of the perceived separation during preswing is related to the fit of the socket.