Orthopaedic Research Laboratories

Other

A Seth Greenwald

Majid Rashidi

Paul D Postak

Derek S Porritt

Alon Katz

Steven P Combs

Mary-Blair Matejczyk

John J Brems

Jack M Geiger

Nathaniel C Narten

A testing apparatus for exposing an associated specimen(s) to motions along multiple axes is provided. The testing apparatus includes a test chamber and first, second, third, and fourth devices that impose different kinematic motions or forces on the specimen. A drive mechanism is connected to the first, second, third, and fourth devices so that motion from a single axis is conveyed by the first, second, third and fourth devices to deliver the desired kinematic motions and/or forces to the test chamber(s). At least one of the first, second, third, and fourth devices includes an adjustment mechanism to modify at least one of the devices.

Adjustable testing apparatus for an orthopaedic specimen such as a knee implant prosthesis

A testing apparatus is provided for exposing an associated specimen to movement along multiple axes. A test chamber is dimensioned to receive the associated specimen. A first device is operatively connected to the test chamber to impose a first, rotational movement on the associated specimen, a second device is operatively connected to the test chamber to impose a second, rotational movement different than the first movement on the associated specimen, a third device is operatively connected to the test chamber to impose a generally planar movement or linear translation on the associated specimen, and a fourth device is operatively connected to the test chamber to impose a load force on the associated specimen. A drive mechanism is operatively connected to the first, second, third, and fourth devices so that the movements and forces imposed by respective ones of the devices are commonly driven by the drive mechanism.

Testing apparatus for an orthopaedic specimen such as a knee implant prosthesis

A single drive shaft simulator and method is disclosed that allows up to four independent actions to be imposed on a test specimen such as an artificial joint specimen. These motions about mutually orthogonal axes are provided, and a constant compressive force and/or dynamic force may also be applied. The mechanical simulator is simple, accurate, and robust. The simulator assures synchronous movement where amplitude and profiles of the motion can be independently adjusted.

Simulator for evaluating artifical joint specimens and associated method

The suction lavage system of this invention incorporates a pulsatile water lavage in combination with a suction system to improve the interface between a prosthesis, such as a hip replacement, and the interdigitating network of cancellous bone in which it is secured with acrylic cement. The water lavage effectively evacuates the medullary fat and hematopoietic tissue from the trabecular interstices of cancellous bone. The suction irrigation system comprises a probe having two configurations which assist in impinging water on cancellous bone for evacuating fat and tissue along with water to improve the interface between the bone and cement. It has been found that weakening of the interface through stress may result in loosening of a prosthesis. The probe consists of a water conduit generally located on the outside of a suction conduit. The suction opening is located below the aperture for the pulsatile jet a distance large enough to insure that the apertures are not immersed in irrigating fluid; the apertures may be displaced to the side or down, or some combination of the two. The water jet pulses at about 2100 pulses per minute. In order to operate to maximum advantage, the pulsatile jet must function in an air environment. This is insured by the fact that the suction outflow is greater than the fluid inflow. The method of this invention, then, relates to preparing cancellous bone to secure a prosthesis, which is achieved by reaming out of the cancellous bone to fit the prosthesis; suction lavaging the cavity with a probe which includes a pulsatile jet of water to evacuate the water, fat and tissue; and securing the acrylic bone cement to the prepared cancellous surface. In the method of this invention, it is possible to increase the interface shear strength of the lavaged preparation by 162%, which is significant in terms of a control which normally uses saline solution.

Method of suction lavage

A prosthetic joint of the type used to replace dysfunctional non-weight bearing joints such as the knuckle, wrist, elbow or shoulder. The preferred embodiment comprises a radial component connected by a concavo-convex socket component to a metacarpal component. The radial component has an intramedullary stem terminating in a cup having a plurality of inwardly extending pins. The concavo-convex socket component is retained in the cup by the articulation of the pins with a plurality of flats which communicate with slots which terminate in apertures. The concavo-convex component includes an opening extending inwardly from one end thereof which defines two communicating bearing surfaces, with the innermost surface being spherical and the outer surface being frusto-conical and having an elliptical cross-section. The metacarpal component includes a ball, a neck area and an intramedullary stem. The ball articulates with the spherical surface of the concavo-convex member component and the neck, which also has an elliptical cross-section, articulates with the frusto-conical surface. The intramedullary stem which is connected to the cup is offset volarly by an amount equal to the offset in the metacarpal component thereby providing a greater moment arm for the weaker tendons of the wrist.

Growing community of inventors

Cleveland Heights, OH, United States of America

A Seth Greenwald