University of Michigan

Other

Larry S Matthews

Steven A Goldstein

Herbert Kaufer

David Ansel Sonstegard

An improved prosthesis interface surface is incorporated on any implantable component where stable long lasting bone fixation is needed. The surface achieves immediate stabilization of the prosthetic component and promotes bony tissue ingrowth by either making the surface of a porous metal or ceramic or coating the surface of the interface surface with a porous metal or ceramic. In the preferred embodiment, the surface includes a large number of conical protrusions which are specifically designed to resist shear and torsional disruptive forces while accommodating the compression loads that occur during motion of a joint prosthesis. By utilizing a series of conical protrusions, the surface contact area of the interface surface is much greater than interface surfaces now in use and this large surface contact area improves stability and provides a large area for secure bony ingrowth fixation. The improved prosthesis interface surface of the present invention may be used in hip, knee, ankle and shoulder joint replacement components as well as in any other implant component which is to be secured in trabecular bone. Additionally, the interface surface may be used to implant artificial dentures and for bony insertions of artificial ligaments and tendons. In another aspect of the present invention, a method of implanting artificial joints utilizing the improved prosthesis interface surface includes in one embodiment the use of a drill guide and in another embodiment a pilot driver.

Prosthesis interface surface and method of implanting

This invention provides a means of measurement tissue pressure in muscle compartments and other regions in humans and other animals. An appropriate length, for example, 6 to 12 inches of thin plastic tubing, typically less than 3 mm outside diameters, is prepared as a working part of the tissue pressure transducer. A portion of the plastic tubing including the thin wall section such as a bubble is inserted into the muscle tissue for which pressure measurement is desired to be made. A fluid is circulated through the tubing at a constant flow rate. When the internal pressure of the tubing is greater than the external pressure, the bubble expands and there is no increase in the flow resistance of the system. When the pressure on the outside exceeds the normal system operating pressure, the thin wall section or bubble contracts, resistance to flow increases, and the system pressure increases. This increase in system pressure is directly proportional to tissue pressure.

Tissue pressure measurement transducer system

Disclosed herein are embodiments of a flexible connecting shaft for an intramedullary reamer. In each embodiment, several short segments or links are attached together to form an elongated flexible shaft which shaft is designed, due to the specific attachment means for the links, to bend along its longitudinal axis while transmitting torque without any lag in such transmission. A link at one end of the flexible shaft as made by a plurality of the links includes means provided for attachment to a torque providing device such as an electric motor. At the opposite end of the shaft, the last link includes structure thereon enabling connection to a drill bit. The various embodiments disclose different ways of interconnecting the links.

Flexible connecting shaft for intramedullary reamer

An improved prosthesis interface surface is incorporated on any implantable component where stable long lasting bone fixation is needed. The surface achieves immediate stabilization of the prosthetic component and promotes bony tissue ingrowth by either making the surface of a porous metal or ceramic or coating the surface of the interface surface with a porous metal or ceramic. In the preferred embodiment, the surface includes a large number of conical protrusions which are specifically designed to resist shear and torsional disruptive forces while accommodating the compression loads that occur during motion of a joint prosthesis. By utilizing a series of conical protrusions, the surface contact area of the interface surface is much greater than interface surfaces now in use and this large surface contact area improves stability and provides a large area for secure bony ingrowth fixation. The improved prosthesis interface surface of the present invention may be used in hip, knee, ankle and shoulder joint replacement components as well as in any other implant component which is to be secured in trabecular bone. Additionally, the interface surface may be used to implant artificial dentures and for bony insertions of artificial ligaments and tendons. In another aspect of the present invention, a method of implanting artificial joints utilizing the improved prosthesis interface surface includes, in one embodiment, the use of a drill guide, and in another embodiment, a pilot driver.

An intramedullary reamer comprising a tapered cylindrical body member, a groove extending along the opposite sides and across the small end of the body member, a plurality of longitudinally disposed valleys disposed in advance of the groove to facilitate removal of cutting chips and a replaceable blade adapted to fit into the groove in the body member, the cutting edge of the blade being exposed above said groove, the open end of the blade being provided with locking means to secure the blade to the body member.

Intramedullary reamer

An universally applicable biopsy needle includes two counter-rotating tubes having oppositely facing sawteeth formed on the distal ends thereof. A gear system transmits a driving force to the tubes, causing the counter-rotation which permits the sawteeth to act in a sawing manner for penetration of bone samples and in a cutting manner for soft tissues. Use of an outer cannula allows safe insertion of the needle to the location of the desired sample, and various grasping means are used to extract the sample core. The concentric, telescoping needles provide a sample preserving the natural architecture and orientation of the tissue or cell types, while minimizing harming and maceration of the same.

Counter rotating biopsy needle

A knee joint prosthesis of the type described in U.S. Pat. No. 3,868,730 has a pair of inwardly sloped radially merging extensions of its condyle runners forming a patella-guiding trough above and between the runners. The extensions merge smoothly into each other at an angle of about 150.degree.. The center of curvature of the base of the trough is about 1.25 inches about a center located a little behind and somewhat above the center of movement of the femoral component. The extension narrows towards its upper portion. The patellar component, which rides in the base of the trough, is made of ultra-high molecular weight polyethylene and has a circular cross section with two bearing surface facets on both sides of a concave arcuate ridge which tracks in the base of the trough, for substantially complete contact between the patellar component and the trough substantially over their full range of movement. The patellar component is retained in a metal holder which has fixation lugs for connecting it under the patella.

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Ann Arbor, MI, United States of America

Larry S Matthews