Harrington Arthritis Research Center

Orthotic Limited Partnership

Allan M Weinstein

James B Koeneman

Thomas M Hansen

Roger H Johnson

Mark Phillips

Thomas P Murray

Joseph A Longo

Ron Yapp

A femoral-side hip-joint prosthetic device for use in hip-joint replacement. The device includes an elongate stem whose surface defines maximally spaced infero-medial and supero-lateral surface curves, and which is characterized by a surface rotation which carries the supero-lateral surface curve about 15.degree.-30.degree. forward with respect to the infero-medial surface curve, on progressing upward along the upper surface portion of the stem, with the device in operative position. The rotation of the stem surface produces a close approximation to the cavity formed in the proximal femur by removal of the cancellous bone in the natural cavity formed by a wall of densified cancellous bone. A 3.degree.-15.degree. proximal anteversion of the neck is adapted to place a hip-joint ball carried on the stem at a position closely approximating that of the head in the natural femur. In the method of the invention, the cavity which receives the prosthesis stem is formed by a rasp/broach-type tool whose surface conforms closely to that of the stem.

Femoral-joint prosthetic device

A unilateral external fixation device comprises a distal frame and a proximal frame interconnected by a hinge formed of mating, partially spherical-shaped surfaces which permits relative movement of the distal frame and proximal frame. Each of the frames includes one or more pin clamps which mount half pins inserted with the proximal or distal segments of a fractured bone to immobilize the bone segments and permit reduction of the fracture. The focal point of the partially spherical-shaped surfaces of the hinge is positioned in direct alignment with the fracture, preferably in a vertical plane passing through the fracture transverse to the longitudinal axis of the bone, so that manipulation of one or both of the distal and proximal frames permits a relatively slight and precise movement of the bone segments connected thereto by the half pins to ensure proper reduction of the fracture.

Unilateral external fixation device

A pin clamp particularly adapted for use in an external skeletal fixation device to clamp pins inserted in the distal segment and/or proximal segment of a fractured bone for positioning and immobilizing the bone segments to reduce the fracture. The pin clamp employs a wedge lock construction including a block having a tapered, hollow interior which receives a wedge element having opposed, tapered sidewalls connected to a slotted top wall. The pins are inserted between the sidewalls of the wedge element into the slot, and are clamped therebetween as the wedge element is moved into the block. A screw carried by the block threads into a bore in the top wall of the wedge element to move the wedge element in and out of the block. Both the block and wedge element are formed of a composite material and the sidewalls of the wedge element which contact the pins are preferably coated with a grit material having a high coefficient of friction.

Pin clamp

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. The filaments which made up the braid in the sheath encircle the core in a helical pattern extending along the stem and tapered section provided resistance to torsional stresses on the stem. Also disclosed are novel methods for making the prosthesis construction.

Beam construction and method

A unilateral external fixation device for closed reduction of simple or comminuted long bone fractures includes a frame formed of composite materials which mounts a proximal carriage at one end and a distal carriage at the other end. The proximal carriage is adapted to mount half pins inserted in the proximal segment, and is supported on the frame by support arms which are movable with respect to the frame for adjusting the position of the proximal segment. The distal carriage includes a clamping member adapted to mount half pins inserted in the distal segment, which is pivotal about the fracture to permit precise adjustment of the distal segment for alignment with the proximal segment. A fragment support, mounted to one of the side rails of the support arm for the proximal carriage, is adapted to clamp a half pin inserted within a central fragment positioned between the proximal and distal segments of a comminuted fracture.

External fixation device

A femoral-side hip-joint prosthetic device for use in hip-joint replacement. The device includes an elongate stem whose surface defines maximally spaced infero-medial and supero-lateral surface curves, and which is characterized by a surface rotation which carries the supero-lateral surface curve about 18.degree.-30.degree. forward with respect to the infero-medial surface curve, on progressing upward along the upper surface portion of the stem, with the device in operative position. The rotation of the stem surface produces a close approximation to the cavity formed in the proximal femur by removal of the cancellous bone in the natural cavity formed by a wall of densified calcellous bone. A 3.degree.-15.degree. proximal anteversion of the neck is adapted to place a hip-joint ball carried on the stem at a position closely approximating that of the head in the natural femur. In the method of the invention, the cavity which receives the prothesis stem is formed by a rasp/broach-type tool whose surface conforms closely to that of the stem.

Growing community of inventors

Paradise Valley, AZ, United States of America

Allan M Weinstein