Abstract: A ratchet tool, including a shaft defining a longitudinal axis; a handle coaxial to the shaft; a first gear immovably fixed to the shaft and disposed in the handle; a second gear rotatably and longitudinally movable with respect to the shaft, where the second gear engages the first gear to limit torque transfer from the handle to the shaft in a first direction and provides substantially zero torque transfer in a second direction; a first spring disposed between the second gear and the handle; a third gear rotatably and longitudinally movable with respect to the shaft, where the third gear engages the first gear to limit torque transfer from the handle to the shaft in the second direction and provides substantially zero torque transfer in the first direction; and a second spring disposed between the third gear and the handle.

Abstract: A ratchet tool, including a shaft defining a longitudinal axis; a handle coaxial to the shaft; a first gear immovably fixed to the shaft and disposed in the handle; a second gear rotatably and longitudinally movable with respect to the shaft, where the second gear engages the first gear to limit torque transfer from the handle to the shaft in a first direction and provides substantially zero torque transfer in a second direction; a first spring disposed between the second gear and the handle; a third gear rotatably and longitudinally movable with respect to the shaft, where the third gear engages the first gear to limit torque transfer from the handle to the shaft in the second direction and provides substantially zero torque transfer in the first direction; and a second spring disposed between the third gear and the handle.

Abstract: A polyaxial tool, including an elongate body defining a first end, a second and a longitudinal axis extending therebetween; the elongate body defining a cavity at the first end; a plurality of arcuate gear teeth circumferentially arranged in the cavity and movable with respect to the elongate body; a socket coupled to the housing and coaxial with the plurality of gear teeth; and a handle coupled to the second end, where an angular position of at least one of the elongate body and handle is adjustable with respect to the plurality of gear teeth.

Abstract: A polyaxial driver system for inserting and setting the angular orientation of an implant includes an elongated component and a distal component. The elongated component extends along a main axis and includes an elongated tubular sheath and an elongated shaft disposed within the tubular sheath. The distal component is pivotally connected to a distal end of the elongated shaft and includes a tubular body extending along the main axis and a spherical head dimensioned to fit and move freely within the tubular body. A proximal end of the elongated shaft includes a first set of outer threads and a proximal end of the elongated tubular sheath includes inner threads shaped and dimensioned to engage the first set of outer threads of the elongated shaft. Rotating the elongated tubular sheath clockwise or counter-clockwise moves the elongated shaft forward or backward along the main axis, respectively.

Abstract: A method of casting a hollow hip prosthesis head comprises forming a wax pattern of a femoral head including two cores. The first is a central socket-forming core and the second a ceramic hollow-forming core. The wax pattern is coated with a ceramic slurry to form a shell in which core extensions are captivated. The wax is melted and evacuated and the shell is fired to form a mould. Metal is cast and, when cool, the shell and cores are removed and each aperture formed in the head by the hollow-forming core is sealed.