Abstract: An improved prosthesis construction in a femoral-side hip joint replacement device of the type having an elongate curved stem held within an intramedullary cavity in a femur, and a neck supporting a ball-like joint member at the femur's proximal end. The construction includes an elongate polymer core containing continuous-filament fibers oriented substantially along the length of the core. The core contains the neck, an elongate distal stem whose cross-sectional area is less than about one-quarter that of the neck, and a tapered sections which mates the neck to the stem. A polymer skin fused to and covering the stem and tapered section of the core is shaped and dimensioned to conform to and fill the bone cavity. A braided sheath encases the stem and tapered sections of the core and it embedded in the polymer skin adjacent the core.