Rotary mill

Abstract

A rotary mill is disclosed comprising a body portion (4) having a milling surface (10) and a central bore (20) extending along an axis of rotation (18) of the body portion (4); and a guide portion (6) having a guide body (22) and a guide peg (24) extending from the guide body (22), the guide peg (24) operable to be received in the central bore (20) of the body portion (4), the guide body (22) having at least one alignment feature (28, 30) which is the same as that of a prosthesis component. A method of implanting a unicondylar femoral component is also disclosed, the method comprising, a) reaming the femoral condylar surface to accept the unicondylar femoral component; b) drilling peg holes for affixing the unicondylar femoral component; c) affixing a guide portion of a rotary mill onto the prepared condylar surface using the drilled peg holes; d) reaming a portion of bone anterior to the affixed guide portion; e) removing the guide portion from the bone; and f) affixing a unicondylar femoral component to the prepared condylar surface.

Description

[0001]The present invention relates to rotary mills and similar rotary cutting devices and particularly but not exclusively relates to rotary mills for use in preparing a bone for total or partial joint replacement surgery.BACKGROUND[0002]It is known to replace all or part of a knee joint in which the joint surfaces have deteriorated, for example as a result of osteoarthritis. Such deterioration usually starts in only one of the tibeo-femoral compartments and may spread to the other at a later stage. Replacement of only one compartment of the joint can therefore be sufficient to provide prolonged relief from symptoms. Damaged bearing surfaces are replaced by a unicompartmental prosthesis which comprises a femoral implant and a tibial implant (usually metallic), which interface through a (polyethylene) bearing component disposed between the two implants.[0003]A unicompartmental or partial knee replacement (PKR) helps to conserve undamaged bone and restores more natural movement to th...

AI Technical Summary

Benefits of technology

The patent describes a guide body for bone removal that has several advantages. Firstly, it can be fixed on the bone surface without needing to remove any additional bone. Secondly, it has alignment features that match those of a prosthesis component, so it can fit into existing recesses in the bone. This eliminates the need for a separate guide rod. The guide body also has nodules that act as depth stops to ensure precise bone removal. Thirdly, the guide peg can be adjusted on the guide body to allow for flexibility in determining the area to be removed. Fourthly, the guide body can be connected to additional surgical tools for reference or for additional bone removal steps. Lastly, the guide body has a biasing element that damps the motion of the guide shaft, providing better control for surgical operations.

Problems solved by technology

However, the design requirements for partial knee replacement prostheses are more demanding than those for total knee replacement prostheses.

Such impingement of the polyethylene bearing component onto the bone can lead to post operative pain, damage to the bearing, increased wear and eventual failure.

However, such a manual procedure can easily be forgotten during surgery and, even when carefully completed, results in an undesirable non uniform bone edge and in the removal of an uncertain and varying amount of bone.

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