Rotary mill

Abstract

A rotary mill (2) comprising a body portion (4) having a milling surface (10) for milling a first bone, a guide portion (6) having a guide body (22), and inter-engageable guide formations (20, 24) formed on the body portion (4) and guide portion (6), the guide body (22) having a projection (7) which is adapted to hold a second bone (11) away from the rotary mill during the milling operation.

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

[0010]The arm may be provided with a recess on a first side which is adapted to accommodate the milling surface without impingement. An opposite side of the arm may be polished chamfered or otherwise shaped such that it does not damage the second bone.

[0011]The guide body may include at least one nodule, protruding from a surface of the guide body and operable to abut a corresponding abutment surface on the body portion. The nodules may thus act as depth stops to ensure a precise amount of bone is removed and avoid excessive bone removal.

[0015]The guide body may be operable to be connected to additional surgical tools, thus facilitating and providing reference for additional bone removal steps.

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.

If the leg is insufficiently flexed or the anatomy of the patient is such that the tibia projects more than is normal, it is possible that the rotary could contact tibia, during milling of the femoral condyle, thereby causing undesirable milling of the surface of the tibia.

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