Threaded femoral shank for hip prosthesis - has threads reducing in depth while retaining their thickness towards distal end of shank for improved retention

摘要

The threaded femoral shank for a hip prosthesis, having each of its generating surfaces curved in an arc with a radius of about one metre for a good engagement with the medullary canal of the femur, has the depth of its thread reducing towards the distal end (2a) of the shank, while the width of the thread increases in the same direction to give a constant thickness at the edges of the thread. The thread spirals are asymmetrical in cross-section, having a flat rear face (14) and a sloping front face (15). The proximal end (2b) of the shank has a truncated conical boss (5) to receive and retain the neck (3), which is equipped with a spherical head (4). The boss (5) has a threaded hole (13) to receive a fixing screw (11) which passes through a hole (12) in the neck to engage with it. ADVANTAGE - Improved shank retention and less discomfort.