Reduction-based joint replacement apparatus and methods

Details Reduction-based joint replacement apparatus and methods Reduction-based joint replacement apparatus and methods

1998-07-15

2001-03-27

Willse, David H. (Department: 3738)

Surgery

Instruments

Orthopedic instrumentation

C623S022120

Reexamination Certificate

active

06206884

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to the field of arthroplasty and, in particular, to methods and apparatus associated with joint replacement, including total hip replacement, using joint reduction as a means to determine optimum positioning of the prosthesis.
BACKGROUND OF THE INVENTION
In total hip replacement, that is, wherein both the ball and socket portions of the hip are replaced with prosthetic components, it is now conventional to use an implant having an intramedullary stem on the femoral side. This stem transitions into a neck and terminates into the ball portion, which engages with acetabulum of the pelvis.
For many reasons, it is difficult to align the components associated with total hip replacement prior to fixation. As a result, the surgical protocol used in conjunction with such procedures often resorts to considerable trial-and-error positioning steps, freehand trimming of host bone, and other time-consuming imprecise steps based largely on the skill and experience of the attending physician. Although modular implants are now used which permit incremental changes in leg length through tapered head attachment to the neck of the stem, many complications have arisen out of such modularity, including dissociation, wear, osteolysis, and implant fracture. Without question any process or instrumentation capable of bringing about more predictable results and accurate alignment in a shorter period of time would be welcome by the medical community.
SUMMARY OF THE INVENTION
This invention resides in methods and apparatus associated with the installation of a properly oriented prosthetic component of the type having an articulating surface adapted to co-act in a joint. The preferred apparatus includes an anchoring unit rigidly connectable to the bone, and a trialing component attachable to the anchoring unit. The trialing component includes an articulating surface corresponding to that of the final implant, enabling a desired orientation of the implant to be established through trial reduction. A cutting guide is provided which is physically indexed to the trialing component, such that when the bone is modified using the guide, a desired implant orientation and joint function may be automatically achieved when the prosthetic component is ultimately installed.
The invention is applicable to a variety of joint situations, particularly ball-and-socket type joint characteristic of the hip and shoulder. In such situations, the anchoring unit is preferably coupled to the bone through implantation within an intramedullary canal. Indeed, the anchoring unit may take the form of a tool of the type typically used to prepare the canal, such as a reamer, broach, or trial stem.
In one configuration, the inventive apparatus further includes means for locking the trialing component into place upon establishing a desired implant orientation and/or joint function, with the anchoring unit being rigidly coupled to the anchoring unit bone through attachment to the trialing component in a locked position. In a different configuration, the bone-cutting guide is coupleable to the anchoring unit through direct attachment to the connection point.
Based upon such apparatus, a method of modifying a bone to receive a prosthetic component according to the invention preferably includes the steps of:
connecting an adjustable trialing component to the bone;
reducing the bone with the trialing component attached to test the joint;
adjusting the position of the trialing component during the trial reduction to achieve a desired orientation;
installing a cutting guide which is physically indexed to the desired orientation established with the trialing component;
modifying the bone using the cutting guide to provide a seating surface; and
installing the prosthetic component such that when at least a portion of the component engages with the seating surface, the prosthetic component assumes the desired orientation


REFERENCES:
patent: 3814089 (1974-06-01), Deyerle
patent: 5690637 (1997-11-01), Wen et al.
patent: 5885297 (1999-03-01), Matsen
patent: 2 737 848 A1 (1997-02-01), None

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