Prosthetic socket design for transfemoral (above-knee) amputations
A primary goal in transfemoral socket design is to maintain the residual hip joint in adduction, which maintains the hip abductors' length and their to produce force. Sockets have evolved from quadrilateral designs toward shapes that prosthetists refer to using acronyms like IC (ischial containment), narrow ML (alluding to their distinctive shape), and NSNA (normal shape-normal alignment) and CAT-CAM (Contoured Adducted Trochanteric-Controlled Alignment Method).
Pritham, C.H. (1989). Workshop on teaching materials for above-knee socket variants. Journal of Prosthetics and Orthotics, 1, 50-67.
Professionals disagree whether AK socket design actually influences the position of the residual femur. For a discussion, see:
Gottschalk, F.A., Kourosh, S. , Stills, M., McClellan, B., & Roberts, J. (1989). Does socket configuration influence the position of the femur in above-knee amputation? Journal of Prosthetics and Orthotics, 2, 94-102.