title: Ideas on the suspension of the below-knee prosthesis.
abstract: Comparative studies with the PTB-suction prosthesis and the ordinary PTB prosthesis have provided opportunities to analyze and understand some functional differences in the suspension of below-knee prostheses. In a roentgenological study of the stump-socket contact signficantly less vertical displacement in the PTB-suction prosthesis has been shown. A study of the pressure variations in the suction socket verified the theory of the necessary pressure gradient in the PTB-suction socket. Added negative pressure by muscle action was also observed. An electromyographic study suggested a muscular activity pattern in the suction prosthesis similar to that of a normal leg, as a contrast to the ordinary PTB prosthesis where simultaneous contractions of antagonistic muscles seemed to be the usual pattern. The latter is interpreted as a defence reaction. An optimal prosthesis has been deduced. It shall have a soft prosthetic socket with a perfect fit, a suction, adhesion and friction fixation and a pressure gradient between the skin and the socket wall with minimum compression distally. The plaster casting shall be done in a downward modelling manner making available space for soft tissue without compression.
mesh_terms: D000671:Amputation, Surgical; D000672:Amputation Stumps; D001186:Artificial Limbs; D001696:Biomechanical Phenomena; D001794:Blood Pressure; D005260:Female; D006801:Humans; D007717:Knee / Q000601:surgery*; D008297:Male; D009119:Muscle Contraction; D011474:Prosthesis Design