WO2021110704A1

WO2021110704A1 - Surgical planers, methods of manufacturing surgical planers and methods for planing bones

Info

Publication number: WO2021110704A1
Application number: PCT/EP2020/084168
Authority: WO
Inventors: Kathiresan RAMU; Bharathiraj PANDIARAJ; Duncan Beedall; Dipumon Ayyanchira Mani; James Naylor
Original assignee: Depuy Ireland Unlimited Company
Priority date: 2019-12-02
Filing date: 2020-12-01
Publication date: 2021-06-10

Abstract

A planer comprising: a housing (10) encasing a drive (150) and a plane (100); the drive defining a drive axis, a drive first end (152) and a drive second end (154), the drive first end arranged to receive a torque and the drive second end coupled to the plane; wherein the housing holds the plane in such a way that a torque applied to the drive causes the plane to oscillate linearly along a translation axis that is offset relative to the drive axis.

Description

SURGICAL PLANERS, METHODS OF MANUFACTURING SURGICAL PLANERS AND METHODS FOR PLANING

BONES

FIELD OF THE INVENTION

[0001] The present invention relates to surgical planers for planing, methods of planing bone and methods of manufacturing surgical planers.

BACKGROUND TO THE INVENTION

[0002] Human and animal bodies have various joints, such as ankles, knees, hips, shoulders and elbows. Joints are formed where two or more skeletal bones meet. Many joints permit movement between them.

[0003] Cartilage is found between the joints that permit motion. Cartilage provides lubrication for the motion and also absorbs some of the forces to which a joint is subjected.

[0004] The cartilage may wear down over time. As a consequence, the bones making up a joint may come into contact leading to pain and reduced joint function.

[0005] Other causes of joint damage is arthropathy. Arthropathy, such as arthritis, is a disease of the joint that may lead to conditions such as pain, stiffness and swelling.

[0006] A hip joint is one of the joints that may experience degradation or disease.

[0007] The hip joint is a ball and socket arrangement formed where the femoral head of a femur meets the acetabulum of the pelvis. The femoral head, which is the ball part of the joint, and the acetabulum, which is the socket part of the joint, are coated with cartilage for allowing the femur to articulate relative to the pelvis.

[0008] Other joints commonly afflicted include those of the spine, knee, shoulder, elbow, carpals, metacarpals and phalanges of the hand.

[0009] An option to treat damaged joints is to replace the parts of the joint that are degraded or diseased with a prosthesis. A commonly used prosthesis is a total joint prosthesis. The total joint prosthesis is used to replace native or natural joint parts with an artificial joint. For example, in a total hip replacement procedure, a natural hip joint may be treated with a total hip replacement prosthesis. The total hip replacement prosthesis includes an artificial femoral part and an artificial acetabular part. [0010] During a total hip replacement procedure, the hip is prepared using specialized instrumentation. One such instrument is a calcar planer. Planers are an instrument used to prepare a part of a femur to receive a part of a total hip replacement prosthesis.

[0011] Typically, during the surgical procedure, a physician takes steps to expose the intramedullary canal of the femur of a patient. The physician prepares the canal to receive the femoral part of the total hip replacement prosthesis. A rasp or broach may be used in said preparation. The broach may be left temporarily implanted in the canal during part of the procedure and a calcar planer engaged with part of the broach.

[0012] Conventional calcar planers include a straight, rigid shaft directly connected at one end to a cutting head. The other end of the shaft is arranged to be coupled rotatably to a power tool.

[0013] During an exemplary surgical procedure, such as a hip replacement procedure, the femur is prepared to receive a femoral part of a total hip replacement prosthesis. Part of the procedure involves planing a surface of the femur. In this part of the procedure a calcar planer is coupled to a power tool and, typically, engaged with a protruding part of a broach. The power tool is driven to rotate the shaft and the cutting head of the planer. The shaft is typically uncovered and may be difficult to grip.

SUMMARY OF THE INVENTION

[0014] According to a first aspect of the present invention, there is provided a planer. The planer may be a surgical planer and be suitable for planing a bone. The surgical planer has a housing encasing a drive and a plane. The drive has a drive axis, a drive first end arranged to receive a torque and a drive second end coupled to the plane. The housing holds the plane in such a way that a torque applied to the drive causes the plane to oscillate linearly along a translation axis. The translation axis may be offset relative to the drive axis.

[0015] The oscillating motion may cause the plane to plane or file a bone in order to true, smooth, flatten or otherwise prepare a part of a bone to have a desired surface profile. The desired surface profile may be a profile suitable for the bone to receive a joint replacement prosthesis. The oscillating motion may minimize jarring of the planer upon contact with a bone.

[0016] Preferably, the housing has a housing first end and a housing second end. The housing second end may hold the plane in such a way that a torque applied to the drive causes the plane to oscillate. [0017] The plane may have a planing arrangement capable of planing or filing a surface. The planing arrangement may include a plurality of ridges. The plurality of ridges may feature blades arranged to plane or file a bone to true, smooth, flatten or otherwise prepare a part of a bone to have a desired surface profile.

[0018] The housing may conceal the drive except for the drive first end and the plane except for the planing arrangement.

[0019] The concealment of the majority of the drive and the majority of the plane may minimize interaction of the moving part of the surgical planer with soft tissues, since the rotating shaft is in a concealed housing.

[0020] Preferably, the housing defines a channel running between a first opening in a or the housing first end and a second opening in a or the housing second end. The drive may be arranged in the channel so that the drive first end is located near the first opening and can receive a torque and the drive second end is located near the second opening.

[0021] Preferably, the housing provides a grip enabling an operator to control the application of the planer to a surface to be planed.

[0022] Preferably, the housing has a first housing portion and a second housing portion that are conjoined to hold the drive shaft and the plane.

[0023] Preferably, the drive and the plane are coupled such that a rotational motion of the drive causes a linear oscillation of the plane in a direction that is parallel to the translation axis.

[0024] Preferably, the drive and the plane are coupled by a slotted link mechanism. For example, the drive and the plane may be coupled by a scotch yoke.

[0025] Preferably, the plane comprises a slot. The drive second end may include a pin. The pin may have a pin axis. An eccentric portion of the pin may extend along the pin axis. The pin axis may be parallel to and eccentric from the drive axis. The pin may be engaged with the slot in such a way that the eccentric portion is arranged to convert a rotating motion of the drive about the drive axis into linear oscillation of the plane along the translation axis.

[0026] The housing may have a housing first end and a housing second end. The housing second end may define a holding area in which the plane is held.

[0027] Preferably, the holding area has an inner wall. The inner wall may have a first elongate side spaced apart from an opposed second elongate side. The first and second elongate sides may be elongate along the translation axis. The plane may be held between the first and second elongate sides. The first and second elongate sides may guide the linear oscillation of the plane relative to the translation axis.

[0028] The planer may have a guide. The guide may be arranged to direct the linear oscillation of the plane relative to the translation axis.

[0029] Preferably, the guide has a ridge and groove arrangement. A ridge and a groove of the ridge and groove arrangement may be elongate in a direction that is parallel to the translation axis.

Abutment of the ridge with the groove may hold the plane in the housing and direct the linear oscillating motion of the plane relative to the translation axis.

[0030] The housing may include the ridge and the plane may include the groove. The ridge and groove arrangement may comprise a first ridge and a second ridge. The first ridge may be located on the first elongate side of the inner wall of the holding area located in the second housing end of the housing.

The second ridge may be located on the second elongate side of the inner wall. The ridge and groove arrangement may comprise a first groove and a second groove located in the plane.

[0031] The plane may have a body that is elongate in a direction that is parallel to the translation axis. The body may include a pair of inner wall facing side faces. The pair of inner wall facing side faces may be located on opposed sides of the body and be arranged to face the inner wall of the holding area. The pair of inner wall facing side faces may include a member of the ridge and groove arrangement. Each face of the pair of inner wall facing side faces may feature a groove capable of receiving a ridge of the ridge and groove arrangement.

[0032] The plane may have a rectangular parallelepiped shaped body. The shape may be defined by a plurality of side faces spacing apart first and second end faces.

[0033] Preferably, the plurality of side faces are elongate in a direction that is parallel to the translation axis. The pair of inner wall facing side faces may be planar and may be parallel with respect to each other. The pair of inner wall facing side faces may be spaced apart from each other by the first and second end faces and by the other pair of side faces. The first and second end faces and the other pair of side faces may space apart the inner wall facing side faces along a transverse axis that is perpendicular to the drive axis and the translation axis.

[0034] The other pair of side faces may include a drive engaging face and a bone engaging face. Preferably, the drive engaging face and bone engaging face are spaced apart in a direction that is parallel to the drive axis. The slot formed in the plane may be defined by a channel connecting an opening in the drive engaging face to an opening in the bone engaging face.

[0035] Preferably, the guide has a guide surface. The guide surface may space apart the surfaces of the inner wall, the guide surface may be arranged to abut the drive engaging face of the plane to thereby guide the oscillation of the plane.

[0036] Preferably, the guide includes the ridge and groove arrangement and the guide surface. [0037] Preferably, the guide surface features an aperture though which the drive, particularly the pin of the drive, passes to form the coupling that coverts a torque applied to the drive into a linear oscillating motion of the plane.

[0038] Preferably, the drive includes a drive shaft aligned with the drive shaft axis, the drive shaft spacing apart the drive first end and the drive second end.

[0039] In a second aspect of the present invention, there is provided a method of planing a bone. The method includes: providing a surgical planer of the first aspect of the present invention; coupling a drive of the surgical planer to a torque applicator; arranging the surgical planer to plane a bone; applying a torque to the drive such that a torque applied to the drive causes the plane to oscillate linearly along a translation axis; and planing a bone using the linearly oscillating plane.

[0040] In a third aspect of the present invention the is provided a surgical planer for planing a bone.

The surgical planer includes a housing, a drive shaft and a file. The housing holds the drive shaft and the file. The drive shaft is elongate along a drive shaft axis and is coupled to the file. The file is configured to plane a bone. A torque may be applied to the surgical planer that is transmitted to the file by the drive shaft. The torque transmission causes the file to reciprocally translate relative to the drive shaft axis along a translation axis that is offset from the drive shaft axis.

[0041] Preferably, the translation axis is perpendicular to the drive shaft axis.

[0042] Preferably, the file extends in a first direction which is parallel to the translation axis and in a second direction which parallel to a transverse axis. Preferably, transverse axis is perpendicular to the drive shaft axis and the translation axis.

[0043] Preferably, the file is elongate along the translation axis.

[0044] Preferably, the file has a plurality of ridges, each ridge having a tip configured to shave a bone. Preferably, each tip is arranged in the same plane that extends in a first direction and a second direction. The first direction may be parallel to the translation axis and offset from the drive shaft axis. The second direction may be parallel to a transverse axis and perpendicular to the drive shaft axis. The transverse axis may be perpendicular to both the drive shaft axis and the translation axis.

[0045] Preferably, the drive shaft has a first end and a second end. The first end may be arranged to be coupled to a drive mechanism. The second end may be coupled to the file. The file may have a filing arrangement configured to shave a bone. The housing may conceal the drive shaft and the file except for the first end and the filing arrangement.

[0046] Preferably, the housing has an external surface defining a grip.

[0047] Preferably, the housing may include a first portion and a second portion. The first portion may be coupled to the second portion to hold the drive shaft and the file in position in the housing.

[0048] Preferably, a scotch yoke-like coupling connects the drive shaft to the file.

[0049] According to a fourth aspect of the present invention, there is provided a method of manufacturing a surgical planer. The method may include the steps of: providing a first and a second housing member; providing a drive shaft having a first end spaced apart from a second end relative to a drive axis, the first end configured to be coupled to a drive mechanism; providing a file having a filing arrangement configured to shave a bone; arranging the file in a first housing member; arranging the drive shaft in the first housing and coupling a second end of the drive shaft to the file; arranging the second housing member to cover the drive shaft and the file; and fixing the first and second housing members together to form a housing that holds the drive shaft and the plane.

[0050] The drive shaft and the file may be held in the housing in such a way that the housing conceals the drive shaft except for the first end and the file except for the filing arrangement.

[0051] The drive shaft and the file may be held in the housing in such a way that a torque applied to the drive shaft causes the file to oscillate linearly in a direction that is offset from the drive axis.

[0052] According to a fifth aspect of the present invention, there is provided a surgical planer. The surgical planer is capable of planing a bone. The surgical planer includes a body housing a drive shaft and a plane. The drive shaft may have a drive shaft axis, a shaft first end arranged to receive a torque and a shaft second end coupled to the plane. The body may hold the plane in such a way that a torque applied to the shaft first end is transmitted to the plane by the shaft second end and causes the plane to reciprocally translate relative to the drive shaft axis in a plane extending out from the drive shaft axis. [0053] Preferably, the body has a body first end and a body second end, the body second end configured to hold the plane in such a way that a torque applied to the shaft first end causes the reciprocal translation of the plane.

[0054] Preferably, the body defines a channel running between a first opening in a or the body first end and a second opening in a or the body second end. The drive shaft may be arranged in the channel so that the shaft first end is located near the first opening and can receive a torque and the shaft second end is located near the second opening.

[0055] Preferably, the body defines a grip zone between a or the body first end and a or the body second end.

[0056] Preferably, the body is divided into a first body portion and a second body portion that are conjoined to hold the drive shaft and the plane.

[0057] Preferably, a scotch yoke-like drive mechanism couples the second end to the plane member. [0058] Preferably, the plane has a slot. The second end of drive shaft has a pin extending parallel to and offset from the drive shaft axis. The pin may be engaged with the slot to couple the drive shaft to the plane.

[0059] Preferably, the plane reciprocally translates relative to the plane in a translation direction. The body second end may define a holding area in which the plane is held. The holding area may have a perimeter comprising a first side spaced apart in the translation direction from an opposed second side. The plane may reciprocally translates within the holding area between the first side and the second side. [0060] Preferably, the plane has a first edge spaced apart in the translation direction from an opposed second edge by a length LP. When measured in the translation direction, the first side of the holding area may be displaced from the second side by a length LH. The distance the plane reciprocally translates in a revolution of the drive shaft may be less than or equal to result of the calculation LH - LP such that the plane reciprocally translates within the holding area between the first side and the second side. [0061] Preferably, relative to the plane the plane reciprocally translates a displacement which is twice the radius measured from the drive shaft axis to a point on a or the pin used to couple the drive shaft to the plane that is the maximum distance from the drive shaft axis.

A BRIEF DESCRIPTION OF THE DRAWINGS

[0062] For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description taken in connection with the following drawings, in which:

[0063] Fig. 1 shows a perspective view a surgical planer of an embodiment of the present invention;

[0064] Fig. 2 shows an exploded, perspective view of the surgical planer shown in Fig. 1;

[0065] Fig. 3 shows an exploded view of a coupling of the surgical planer shown in Fig. 1;

[0066] Fig. 4 shows a sectional view of an end of the surgical planer shown in Fig. 1;

[0067] Fig. 5 shows a view of the distal end of the surgical planer shown in Fig. 1 in different phases of operation; and

[0068] Fig. 6 shows an illustrative view of the surgical planer shown in Fig. 1 coupled to a power tool;

[0069] Fig. 7 shows an illustrative view of the surgical planer of Fig. 1 in use planing a surface of a bone; and

[0070] Fig. 8 shows an illustrative view of the surgical planer of Fig. 1 being griped for use in planing a surface of a bone.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0071] The present invention is a surgical planer. The surgical planer has a plane. The plane is held by the surgical planer in such a way that it can reciprocally translate. The forwards and backwards motion of the plane is used by, for example, a physician during a surgical procedure to true, smooth, flatten or otherwise prepare a part of a bone to have a desired surface profile, for example, a planar surface.

[0072] The plane is oscillated, or reciprocally translated, by a drive shaft. The reciprocal motion may file the bone. Due to the reciprocal translation, the plane may file the bone's surface without becoming jarred or stuck upon contact with a bone.

[0073] The plane and the drive shaft can be considered as being movable parts of the surgical planer. The housing holds the plane and the drive shaft. The housing may conceal the majority of the plane and the drive shaft. This concealment by the housing may minimize interaction in use of the movable parts with, for example, soft tissue of a person whose bone is being planed.

[0074] Referring to Fig. 1, the surgical planer 1 has a housing 10, a plane 100 and a drive 150.

[0075] The housing 10 holds the plane 100. The housing 10 houses a major portion of the drive 150. [0076] The housing 10 has a distal end 12 and a proximal end 14.

[0077] The plane 100 is located in a distal end 12 of the housing 10.

[0078] From the distal end 12, the housing 10 extends along a central axis CA to the proximal end 14. [0079] The housing 10 has a holder 16 and a grip 18. The holder 16 is located at the distal end 12. The grip 18 extends from the holder 16 to the proximal end 14.

[0080] The grip 18 is provided by an external surface of the housing 18 that extends from the holder 16. [0081] The holder 16 holds the plane 100.

[0082] The grip 18 encases the major portion of the drive 150. The grip 18 may facilitate manipulation of the surgical planer 1 by an operator. The manipulation may facilitate easier location of the plane 100 at a desired location on a bone.

[0083] The arrangement of the drive 150 in the housing 10 allows an operator to conveniently grip the plane 1 whilst the drive 150 is rotated.

[0084] The operator may grip the housing 10 to position the plane in a desired location relative to a bone and use the planer 1 to prepare the bone.

[0085] The operator may grip the grip 18 whilst a torque is applied to the drive 150 by a power tool and the bone is being planed.

[0086] The ability of an operator to grip the planer 1 may facilitate improved control when compared to a conventional planer in which the drive shaft is not encased in a housing 10.

[0087] The housing 10 holds the components 100, 150 in position so that the plane 1 can be used to plane a bone.

[0088] The plane 100 has a cutting arrangement 102. The cutting arrangement 102 is located on a bone engaging face 103 of the plane 100. The cutting arrangement 102 can be used to plane a bone. [0089] The cutting arrangement 102 has a series of plane ridges 104. Each ridge of the series of plane ridges 104 defines a blade 106 capable of shaving a layer of bone. As a person of skill in the art would understand, other cutting arrangements are of course possible. For example, the cutting arrangement 102 could include a plurality of small teeth arranged to file a part of a bone in preparation for receipt of a joint replacement prosthesis.

[0090] Each plane ridge 104 and its corresponding blade 106 runs parallel to a transverse axis TRA. The transverse axis TRA is perpendicular to the central axis CA. The transverse axis TRA is perpendicular to the translation axis TLA.

[0091] The plane ridges 104 along with the respective blades 106 are parallel to each other.

[0092] As a person of skill in the art would understand, ridges and blades can be orientated in any manner suitable for cutting bone.

[0093] Each plane ridge 104 has the same height such that each one of the blades 106, or tips, are arranged in a plane. The plane is perpendicular to the central axis CA in a direction that is parallel to the translation axis TLA and in a direction that is parallel to the transverse axis TRA. Arranging the blades 106, or tips, in the same plane results in the planer 1 capable of preparing a flat surface.

[0094] The drive 150 is coupled to the plane 100 so that a torque applied to the drive 150 causes the plane 100 to oscillate.

[0095] The drive 150 extends through the housing 10 concentrically with the central axis CA. The drive extends from a trailing end 152 to a leading end 154.

[0096] The trailing end 152 extends externally from the housing 10. The trailing end 152 extends through and away from the proximal end 14. The trailing end 152 is configured to be coupled to a power tool, such as a power tool P shown in Fig. 7. [0097] Referring again to Fig. 1, the leading end 154 is arranged through a slot 110 in the plane 100.

The arrangement of the leading end 154 through the slot 110 forms a slotted link, or scotch yoke, coupling.

[0098] The plane 100 is held by the housing 10 in such a way that a torque applied to the drive 150 by the drive tool causes the plane 100 to oscillate in a direction that is perpendicular to the central axis CA and parallel to a translation axis TLA.

[0099] The slotted link, or scotch yoke, coupling connects the drive 150 to the plane 100. The coupling 110, 154 coverts a rotating motion of the drive 150 about the central axis CA into a linear oscillating motion of the plane 100 in a direction that is parallel to the translation axis TLA.

[0100] It is of course possible that in other embodiment of the present invention, the plane 100 may be oscillated, or reciprocally translated, relative to a central axis in other angular orientations, as person of skill would understand.

[0101] With reference to Fig. 2, the housing 10 has a first housing member 10A and a second housing member 10B. The first and second housing members 10A, 10B have connectors 42. The connectors 42 are arranged about the perimeter of the housing members 10A, 10B.

[0102] The first and second housing members 10A, 10B may be pressed together causing the connectors 42 to couple the first housing member 10A to the second housing member 10B. The connectors 42 may be a pair of male and female connectors arranged to receive one another.

[0103] Except for the connectors 42, the first housing member 10A is a mirror image of the second housing member 10B.

[0104] The first and second housing members 10A, 10B are coupled by pressing them together. The first and second members 10A, 10B are pressed together to form the housing 10 that holds the plane 100 and the drive 150.

[0105] The holder 16 of the housing 10 holds the plane 100.

[0106] The grip 18 of the housing 10 holds the drive 150.

[0107] For simplicity and with reference to Fig. 2, features of the planer 1 will be described as though first and second housing members 10A, 10B have been pressed together.

[0108] The housing 10 has an inner wall 11. The inner wall 11 has a channel 32 defined in the grip 18. [0109] When the housing 10 is formed by pressing the housing members 10A, 10B together, the channel 32 encases the majority of the drive 150.

[0110] The channel 32 has a first opening 34 into the holder 16. The first opening 34 is gap in a first collar 34A through which a portion of the drive 150 fits. The first collar 34A marks the transition between the holder 16 and the grip 18.

[0111] The channel 32 extends along the central axis CA from the first opening 34 to a second opening 36. The first opening 34 is spaced apart from the second opening 36 relative to the central axis CA by a grip body 38.

[0112] The second opening 36 is formed at a point where the width of the channel 32 narrows to form a second collar 36A. The second collar 36A defines the second opening 36 and is circular in shape.

[0113] The second collar 36A is formed where the channel 32 narrows from a first width to a second, narrower width. The second collar 36A abuts a portion of the drive 150 where it narrows from the drive shaft 156 to form the trailing end 152. The second collar 36A serves to hold the shaft 150 in the housing 10 after the planer 1 has been assembled. [0114] The holder 16 is configured to hold the plane and to guide the oscillations of the plane relative to the translation axis TLA.

[0115] The holder 16 is elongate in a direction that is parallel to the translation axis TLA.

[0116] The inner wall 11 defines a holding area 20 of the holder 16 in which the plane 100 is held. [0117] The holding area 20 includes a portion of the inner wall 11 and has a shoulder 20A.

[0118] The shoulder 20A is located adjacent the first collar 34.

[0119] The shoulder 20A is located distally from the first collar 34 relative to the central axis CA.

[0120] The holding area 20guides the oscillations of the plane 100.

[0121] The holding area 20extends in a direction that is parallel to the central axis CA distally from the shoulder 20A to the distal end 12.

[0122] The holding area 20 surrounds the central axis CA.

[0123] With reference to Fig. 5, the holding area 20 defines a rectangular shaped recess 22. The rectangular shaped 22 recess has curved corners. Of course, any shaped recess could be used as a person of skill in the art would understand.

[0124] The holding area 20 is elongate in a direction that is parallel to the translation axis TLA. The holding area 20 is longer than the plane 100 in a direction that is parallel to the translation axis TLA such that the plane 100 can oscillate, or translate reciprocally, between opposed ends of holding area 20 .

[0125] Referring again to Fig. 2, the holding area 20 has first and second elongate sides 21A, 21B spaced apart in a direction that is perpendicular to the translation axis TLA. The first and second elongate sides 21A, 21B are elongate in a direction that is parallel to the translation axis TLA.

[0126] the shoulder 20A extends inwardly from the holding area 20 in a direction that is parallel to the translation axis TLA and perpendicular to the central axis CA.

[0127] The holding area 20 provides a guide arrangement for guiding the oscillation of the plane 100. [0128] The shoulder 20A provides a guide surface of the guide arrangement.

[0129] The first and second elongate sides 21A, 21B provide guide surfaces of the guide arrangement. [0130] The combination of the guide surfaces 20A, 21A, 21B provided by the holding area 20 provides the guide arrangement 20A, 21A, 21B.

[0131] The guide arrangement 20A, 21A, 21B guides the plane 100 as it moves backwards and forward linearly relative to the translation axis TLA.

[0132] A further part of the guide arrangement is provided by a set of guide ridges 44 located in the holding area 20 and grooves 114 located in the plane 100.

[0133] Referring to Fig. 4, the guide ridges 44 are located on the elongate sides 21A, 21B. A first guide ridge 44A is located on the first elongate side 21A. A second guide ridge 44B is located on the second elongate side 21B. The guide ridges 44A, 44B are elongate in a direction that is parallel to the translation axis TLA (not shown in Fig. 4).

[0134] The guide ridges 44A, 44B extend inwardly a short distance from the holding area 20 in a direction that is perpendicular relative to the central axis CA. The guide ridges 44A, 44B are located distal from the shoulder 20A and proximal to the distal end 12. That is, the guide ridges 44A, 44B are positioned on the holding area 20 in between the shoulder 20A and the distal end 12.

[0135] As well as guiding the direction in which the plane 100 oscillates, the guide ridges 44A, 44B are used to hold the plane 100.

[0136] The plane 100 is held between the first and second elongate sides 21A, 21B. [0137] Referring again to Fig. 2, the plane 100 has a body 101 that is elongate in a direction that is parallel to the translation axis TLA.

[0138] The body 101 has a rectangular parallelepiped shape.

[0139] The body 101 has four major faces 101A, 101B, 101C, 101D and two minor faces 101E, 101F.

The faces define the shape of the body 101.

[0140] The four major faces 101A, 101B, 101C, 101D are a plurality of side faces that are elongate in a direction that is parallel to the translation axis.

[0141] The two minor faces are a pair of end faces 101E, 101F.

[0142] A first pair of major faces 101A, 101B are located on opposed sides of the body 101. A second of pair of opposed major faces 101C, 101D extends between and spaces apart the first pair of major faces 101 A, 101B.

[0143] The transition between the first pair of major faces 101A, 101B and the pair of end faces 101E, 101F is curved. The curved corners result in the body 101 having a curved rectangular shape when viewed from the distal end.

[0144] When held in the housing 10, the first pair of major faces 101A, 101B are aligned with the elongate sides 21A, 21B.

[0145] With reference to Fig. 4, the first pair of major faces 101A, 101B each have a groove 114A, 114B of the grooves 114 forming a part of the guide arrangement.

[0146] Each groove 114A, 11B is elongate in a direction that is parallel to the translation axis (not shown in Fig. 4). Each groove 114A, 114B is arranged to receive a ridge 44A, 44B. Each groove 114A, 11B is longer than a corresponding ridge 44A, 44B so that the plane 100 is able to oscillate back and forth as the drive shaft 150 is rotated.

[0147] The ridges 44A, 44B ridge and grooves 114 constitute a ridge and groove arrangement 44A, 44B, 114.

[0148] The ridge and groove arrangement 44A, 44B, 114A, 114B and the holding area 20 form a guide arrangement for guiding the oscillation of the plane 100 perpendicular to the central axis CA and parallel to the translation axis TLA.

[0149] A face 101C of the second pair of major faces is a drive engaging face.

[0150] A face 101D of the second pair of major faces is a bone engaging face. The bone engaging face 101D includes the cutting arrangement 102.

[0151] The drive engaging face 101C and bone engaging face 101D are spaced apart in a direction that is parallel to the central axis CA.

[0152] The slot 110 is formed in the plane 100. The slot 110 is a channel connecting an aperture in the drive engaging face 101C to an aperture in the bone engaging face 101D.

[0153] The leading end 154 is arranged through the slot 110 to provide the slotted link, or scotch yoke, coupling.

[0154] Referring again to Fig. 2, the leading end 154 features a protrusion 158. The protrusion 158 extends from the shaft 156. The protrusion 158 is coupled to the plane 100. The protrusion 158 transmits a torque applied to the trailing end to the plane 100.

[0155] The protrusion 158 has a first portion 159 and a second portion 160.

[0156] The first portion 159 extends from the shaft concentrically with the central axis CA. [0157] The second portion 160 extends from the shaft 156 concentrically with a protrusion axis PA.

The protrusion axis PA extends parallel to the central axis CA. The protrusion axis PA is eccentric relative to the central axis CA.

[0158] Due the second portion 160 being eccentric relative to the central axis, a coupling is formed that converts a rotating motion of the drive 150 into a linear, oscillating motion of the plane 100.

[0159] Of course, as a person of ordinary skill would understand, any coupling capable of converting a rotating motion into a linear motion may be suitable for use a coupling of an embodiment of the present invention.

[0160] When the body portions 10A, 10B are pressed together to form the housing 10, the majority of the drive 150 is concealed in the housing 10.

[0161] The leading end 154 is spaced apart from the trailing end 152 by the shaft 156. The leading end 154 is coupled to the plane 100, particularly the slot 110 of the plane. The shaft 156 is housed by the channel 32. The trailing end 154 extends from the housing proximally from the housing 10.

[0162] The shaft 156 is arranged concentrically to the central axis CA. The central axis CA passes through the trailing end 152 and the leading end 154.

[0163] The trailing end 152 is shaped to enable coupling of the drive 150 to a drive or power tool. The shape of the trailing end 152 enables a power tool to rotate the drive about the central axis CA. The trailing end 152 may be shaped to receive any form of coupling. For example, the trailing end 152 may be shaped to receive a Hudson coupling or an AO coupling. As a person of skill in the art would understand, other suitable couplings may be used.

[0164] With reference to Fig. 3, for simplicity, the plane 100 and portion of the drive 150 that is to be coupled to the plane 100 is shown.

[0165] The slot 110 is configured to receive the protrusion 158 and is configured to covert a rotating motion of the drive 150 into a linear motion of the plane 100. The protrusion 158 is arranged in the channel 110 to form a scotch yoke-like coupling. This type of coupling enables conversion of a rotating motion of the drive shaft 150 into a linear motion of the plane 100. As person of skill in the art would understand, other forms of coupling, such as an appropriately configured rack and pinion coupling, are of course possible.

[0166] In use, the plane 100 reciprocally translates, or oscillates, upon application of a torque to the drive 150. A physician, or other operator, may apply the oscillating plane 100 to a bone. The forwards and backwards motion of the plane gradually cuts the bone to true, smooth, flatten or otherwise prepare a part of a bone to have a flat or relatively smooth surface.

[0167] The slot 110 is shaped and dimensioned to receive the protrusion 158. The shape of the slot 110 is selected so that the second, eccentric portion 160 causes the plane 100 to oscillate as the drive 150 is rotated.

[0168] The slot 110 has a curved rectangular shape.

[0169] The slot 110 is elongate in a direction that is perpendicular to the translation axis TLA.

[0170] The slot 110 runs parallel to the central axis CA.

[0171] Referring again to Fig. 4, the slot 110 is formed by openings 111A, 111B on the bone engaging and the drive engaging faces 101C, 101D of the plane 100 that are connected by a channel 111C.

[0172] The channel 111C is defined by an internal side wall that, when viewed in cross-section, has a curved rectangular shape. [0173] The plane 100 is held in the housing 10 by the holder 16.

[0174] The cutting arrangement 102 extends a short distance from the distal end 14 of the housing 10. [0175] The ridge and groove arrangement 44A, 44B, 114A, 114B holds the plane 100 in place in the housing 10.

[0176] A first ridge 44A engages a first groove 114A. A second ridge 44B engages a second groove 114B.

[0177] When the housing members 10A, 10B are pressed together to form the housing 10, the first and second ridges 44A, 44B are engaged with the first and second grooves 114A, 114B. The engagement of the ridges 44A, 44B with the grooves 114A, 114B holds the plane 100 in the housing 10.

[0178] With reference to Fig. 5, an oscillation cycle will now be described.

[0179] In use, the plane 100 is oscillated in a direction that is parallel to the translation axis TLA and may be brought into contact with a surface. During each oscillation, the plurality of plane ridges 104 are moved forwards and backwards to thereby remove a layer from said surface. This forwards and backwards motion can be thought of as a filing motion. In this way, the plane 100 may be described as a file and the plurality of ridges 104 may be described as a filing arrangement that incrementally removes a layer from the surface with each oscillation.

[0180] The plane or file 100 may be applied to a surface and used by an operator to file the surface. With each oscillation, the plane or file 100 incrementally removes a thin layer of material from the surface. The removal of thin layers in increments may result in more gradual and controlled removal of material from the surface to which it is applied.

[0181] Moving from the leftmost image, labelled Step 1, to the rightmost image, labelled Step 4, an oscillation of the plane 100 can be seen.

[0182] Relative to the first protrusion 159 which is concentric to the central axis CA (not shown), the drive 150 is rotated to transition the eccentric portion 160 from a north position to a west position (Step 1 to Step 2), from a west position to a south position (Step 2 to Step 3) and from a south position to an east position (Step 3 to Step 4). As a person of ordinary skill would understand, the drive 150 continues to be rotated thereby causing the eccentric portion 160 to return to the north position (Step 1)·

[0183] When the eccentric portion 160 is in the north position, as shown in the leftmost image, labelled Step 1, the end face 101E of the plane 100 is arranged at one end of the holder 16. As the eccentric portion 160 transitions to the south position, as shown by the middle right image, labelled Step 3, the plane 100 is moved linearly relative to the translation axis to an opposed end of the holder 16. When the eccentric portion is in the south position, labelled Step 3, the other end face 101F of the plane 100 is arranged at the opposed other end of the holder 16.

[0184] To complete the oscillation, the eccentric portion 160 is returned to the north position, which moves the plane 100 to the position shown in the leftmost image, labelled Step 1.

[0185] The oscillations are continued cyclically until the operator is satisfied that the plane, or file, 100 has filed or planed a surface with desired surface profile.

[0186] To control placement of the planer 1, the first, central portion 159 of the protrusion 158 has a circular recess 162. The circular recess 162 is dimensioned to receive a part of a femoral trial stem or broach (not shown) and provides a central point about which the plane 100 can be oscillated.

[0187] The portion 20 of the inner wall 11 that forms the holder 16 has a length L_H of 40mm and a width W_Hof 25mm. [0188] The plane 100 has a length L_Pof 12mm and a width W_Pof 25mm.

[0189] With reference to Fig. 6, the planer 1 is typically coupled to a drive or power tool P for use in part of a surgical procedure in which a portion of the femur is planed or filed.

[0190] The trailing end 152 (not shown in Fig. 6) is coupled to a coupling C of the power tool P to configure the planner 1 for use.

[0191] The planer 1 is provided to an operator for use in planing a bone.

[0192] With reference to Fig. 7, the operator arranges the planer at a desired location on the bone.

For example, when the planer 1 is used to plane a surface of a femur F, the plane is located at an appropriate point on a femur F.

[0193] The power tool P is used to apply a torque to the trailing end 152.

[0194] The torque is transmitted to the plane 100 by the shaft second end 154. Consequentially, the plane 100 reciprocally translates, or oscillates, relative to the central axis CA in a direction that is offset from the drive shaft axis.

[0195] The plane 100 is pressed against the bone and oscillated until the operator is satisfied that the desired surface has been prepared.

[0196] Before pressing the planer 1 against the bone, the operator may first have arranged the planer 1 to be engaged with a protrusion extending from a broach (not shown), or a trial femoral stem (not shown). In order to so arrange the planer 1, the circular recess 162 is positioned over and engaged with the protrusion. The central recess 162 may be used to align the planer 1 with a desired planing location. [0197] Each oscillation of the plane 100 removes a smaller layer of bone incrementally from the surface of the femur F.

[0198] Once the operator is satisfied that the planer 1 has prepared the bone to have a desired surface profile, the operator moves on to the next step in the joint replacement procedure.

[0199] With refence to Fig. 8, the plane 100 is oscillated in a direction that is parallel to the translation axis TLA.

[0200] In the embodiment shown, the plane 100 is offset by 90 degrees relative to the central axis CA. Flowever, as a person of ordinary skill would understand the angle of the translation axis TLA could be varied to be offset at other angles.

[0201] The planer 1 may be gripped by an operator O. The operator O may guide and hold the planer 1 through manipulation of the grip 18.

[0202] Referring again to Fig. 2, the body parts 10A, 10B of the housing 10 are made of polyacrylamide. An example of a suitable polyacrylamide is known as IXEF^®. The body parts, or housing members, 10A, 10B are made through a plastics injection molding process.

[0203] The plane 100 is made of a suitable metal material. For example, the plane may be made from Type 17-4 PH stainless steel stainless steel. The plane 100 may be made through a metal injection molding process.

[0204] The drive shaft 150 may be made of ultra-high-molecular-weight polyethylene through injection molding process

[0205] The planer 1 is assembled by coupling the drive 150 to the plane 100.

[0206] The combination of the plane 100 and the drive 150 is positioned in a first of the housing members 10A. [0207] The plane 100 is positioned in the holder 16 so that the ridge 44A engages with the groove 114A.

[0208] The drive 150 is positioned so that it extends along the central axis CA in the grip 18.

[0209] The ridge 44B of the second housing member 10B is located in the groove 114B of the plane 100.

[0210] The produce the surgical planer 1, the housing members 10A, 10B are pressed together to engage the connectors 42 with each other.

[0211] The surgical planer 1 provides a grip 18 that can be conveniently gripped to manipulate it during a surgical procedure 1. The grip 18 is part of the housing 10 that encases the majority of the plane 100 and the drive 150. This encasement results in a surgical instrument that can be operated with minimal interaction of the moving parts 100, 150 with surrounding tissue. The oscillation of the plane, or file, 100 within the housing provides a controlled way of planing a surface.

[0212] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. [0213] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0214] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0215] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0216] Although preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made without departing from the scope of the invention as defined in the claims.

[0217] In this specification, the terms "comprise", "comprises", "comprising" or similar terms are intended to mean a non-exclusive inclusion, such that a system, method or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed. [0218] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

[0219] It will of course be understood that this description is by way of example only; alterations and modifications may be made to the described embodiment without departing from the scope of the invention as defined in the claims.

Claims

1. A planer comprising: a housing encasing a drive and a plane; the drive defining a drive axis, a drive first end and a drive second end, the drive first end arranged to receive a torque and the drive second end coupled to the plane; wherein the housing holds the plane in such a way that a torque applied to the drive causes the plane to oscillate linearly along a translation axis that is offset relative to the drive axis.

2. The planer of claim 1, wherein the housing has a housing first end and a housing second end, the housing second end may hold the plane in such a way that a torque applied to the drive causes the plane to oscillate.

3. The planer of claim 1, wherein the plane has a planing arrangement capable of filing a surface.

4. The planer of claim 3, wherein the planing arrangement comprises a plurality of ridges, each one of the plurality of ridges comprising a blade arranged to file a bone.

5. The planer of claim 3 or claim 4, wherein the housing encases the drive and the plane so as to conceal the drive except for the drive first end and the plane except for the planing arrangement.

6. The planer of any one of claims 1 to 5, wherein the housing defines a channel running between a first opening in a or the housing first end and a second opening in a or the housing second end; the drive is arranged in the channel so that the drive first end is located near the first opening and can receive a torque and the drive second end is located near the second opening.

7. The planer of any one of claims 1 to 6, wherein the housing provides a grip.

8. The planer of any one of claims 1 to 7, wherein the housing has a first housing portion and a second housing portion that are conjoined to hold the drive shaft and the plane.

9. The planer of any one of claims 1 to 8, wherein the drive and the plane are coupled such that a rotational motion of the drive causes a linear oscillation of the plane in a direction that is parallel to the translation axis.

10. The planer of any one of claims 1 to 8, wherein the drive and the plane are coupled by a slotted link mechanism capable of converting a rotational motion of the drive to a linear oscillation of the plane in a direction that is parallel to the translation axis.

11. The planer of any one of claims 1 to 8, wherein the drive and the plane are coupled by a scotch yoke arranged to convert a rotational motion of the drive to a linear oscillation of the plane in a direction that is parallel to the translation axis. For example, the drive and the plane may be coupled by a scotch yoke.

12. The planer of any one of claims 1 to 9, wherein: the plane comprises a slot; and the drive second end comprises a pin; wherein the pin has a pin axis and an eccentric portion that extends along the pin axis; wherein the pin axis is parallel to and eccentric from the drive axis; and wherein the pin is engaged with the slot in such a way that the eccentric portion is arranged to convert a rotating motion of the drive about the drive axis into linear oscillation of the plane along the translation axis.

13. The planer of any one of claims 1 to 13, wherein the housing has a housing first end and a housing second end; wherein the housing second end defines a holding area in which the plane is held.

14. The planer of claim 13, wherein the holding area has an inner wall having a first elongate side spaced apart from an opposed second elongate side, the first and second elongate sides being elongate along the translation axis; wherein the plane is held such that the first and second elongate sides guide the linear oscillation of the plane relative to the translation axis.

15. The planer of any one of claims 1 to 14, wherein the planer a guide arranged to direct the linear oscillation of the plane relative to the translation axis.

16. The planer of claim 15, wherein the guide has a ridge and groove arrangement; wherein a ridge and a groove of the ridge and groove arrangement may be elongate in a direction that is parallel to the translation axis; and wherein abutment of the ridge with the groove holds the plane in the housing and directs the linear oscillating motion of the plane relative to the translation axis.

17. The planer of claim 16, wherein: the housing comprises the ridge, and the plane comprises the groove.

18. The planer of claim 16 or claim 17, wherein the ridge and groove arrangement comprises a first ridge and a second ridge and a first and a second groove; wherein the first ridge is matingly located in the first groove and the second ridge is matingly located in the second groove.

19. The planer of any one of claims 16 to 17 when dependent on claim 13, wherein the ridge and groove arrangement comprises a first ridge and a second ridge and a first and a second groove; wherein the first ridge is matingly located in the first groove and the second ridge is matingly located in the second groove; wherein the first ridge is located on the first elongate side of the inner wall and the second ridge is located located on the second elongate side of the inner wall; and wherein the first groove and the second groove are located in the plane.

20. The planer of any one of claims 1 to 19 when dependent on claim 13, wherein the plane comprises a body that is elongate in a direction that is parallel to the translation axis; wherein the body comprises a pair of inner wall facing side faces located on opposed sides of the body, each face of the pair arranged to face the inner wall of the holding area.

21. The planer of claim 20 when dependent on any one of claim 16 to 19, wherein the pair of inner wall facing side faces may include a member of the ridge and groove arrangement.

22. The planer of claim 21, wherein each face of the pair of inner wall facing side faces comprises a groove capable of receiving a ridge of the ridge and groove arrangement.

23. A method of planing a bone, the method comprising: providing a surgical planer comprising: a body housing a drive shaft and a plane; the drive shaft comprising a drive shaft axis, a shaft first end arranged to receive a torque and a shaft second end coupled to the plane; coupling the drive shaft to a torque applicator; arranging the surgical planer to plane a bone; and applying a torque to the shaft first end that is transmitted to the plane by the shaft second end to thereby cause the plane to reciprocally translate relative to the drive shaft axis in a plane extending out from the drive shaft axis.

24. A surgical planer for planing a bone comprising: a housing, a drive shaft and a file; the housing holding the drive shaft and the file; the drive shaft is elongate along a drive shaft axis and is coupled to the file; the file arranged to plane a bone; wherein a torque applied to the surgical planer is transmitted to the file by the drive shaft to thereby causes the file to oscillate relative to the drive shaft axis along a translation axis that is offset from the drive shaft axis.

25. The surgical planer of claim 24, wherein the translation axis is perpendicular to the drive shaft axis.

26. The surgical planer of claim 24 or claim 25, wherein the file is elongate along the translation axis.

27. The surgical planer of any one of claims 24 to 26, wherein the file has a plurality of ridges, each ridge having a tip configured to shave a bone.

28. The surgical planer of claim 27, wherein each tip is arranged in the same plane; wherein the plane extends in a first direction and a second direction, the first direction is parallel to the translation axis and offset from the drive shaft axis, and the second direction is parallel to a transverse axis and perpendicular to the drive shaft axis; and wherein the transverse axis is perpendicular to both the drive shaft axis and the translation axis.

29. The surgical planer of any one of claims 24 to 28, wherein the drive shaft has a first end and a second end, the first end arranged to be coupled to a drive mechanism, the second end coupled to the file; wherein the file has a filing arrangement configured to shave a bone; and wherein the housing conceals the drive shaft and the file except for the first end and the filing arrangement.

30. The surgical planer of any one of claims 24 to 29, wherein the housing has an external surface defining a grip.

31. The surgical planer of any one of claims 24 to 29, wherein the housing comprises a first portion and a second portion; wherein the first portion is coupled to the second portion to hold the drive shaft and the file in position in the housing.

32. The surgical planer of any one of claim 24 to 31, wherein a scotch yoke-like coupling connects the drive shaft to the file.

33. A method of manufacturing a surgical planer, the method comprising the steps of: providing a first and a second housing member; providing a drive shaft having a first end spaced apart from a second end relative to a drive axis, the first end configured to be coupled to a drive mechanism; providing a file having a filing arrangement configured to shave a bone; arranging the file in a first housing member; arranging the drive shaft in the first housing and coupling a second end of the drive shaft to the file; arranging the second housing member to cover the drive shaft and the file; and fixing the first and second housing members together to form a housing that holds the drive shaft and the plane.

34. The method of claim 33, wherein the housing conceals the drive shaft except for the first end and the file except for the filing arrangement.

35. The drive shaft of claim 33 or claim 34, wherein the drive shaft and the file are held in the housing in such a way that a torque applied to the drive shaft causes the file to oscillate linearly in a direction that is offset from the drive axis.

36. A surgical planer for planing a bone comprising: a body housing a drive shaft and a plane; the drive shaft comprising a drive shaft axis, a shaft first end arranged to receive a torque and a shaft second end coupled to the plane; wherein the body holds the plane in such a way that a torque applied to the shaft first end is transmitted to the plane by the shaft second end and causes the plane to reciprocally translate relative to the drive shaft axis in a plane extending out from the drive shaft axis.

37. The surgical planer of claim 38, wherein the body has a body first end and a body second end, the body second end configured to hold the plane in such a way that a torque applied to the shaft first end causes the reciprocal translation of the plane.

38. The surgical planer of claim 38 or claim 39, wherein the body defines a channel running between a first opening in a or the body first end and a second opening in a or the body second end; and wherein the drive shaft is arranged in the channel so that the shaft first end is located near the first opening and can receive a torque and the shaft second end is located near the second opening.

39. The surgical planer of any one of claims 38 to 40, wherein the body defines a grip zone between a or the body first end and a or the body second end.

40. The surgical planer of any one of claims 38 to 41, wherein the body is divided into a first body portion and a second body portion that are conjoined to hold the drive shaft and the plane.

41. The surgical planer of any one of claims 38 to 42, wherein a scotch yoke-like drive mechanism couples the second end to the plane member.

42. The surgical planer of claim 43, wherein the plane comprises a slot, and the second end of drive shaft comprises a pin extending parallel to and offset from the drive shaft axis; and wherein the pin is engaged with the slot to couple the drive shaft to the plane.

43. The surgical planer of any one of claims 38 to 44, wherein the plane reciprocally translates relative to the plane in a translation direction; wherein the body second end defines a holding area in which the plane is held, the holding area has a perimeter comprising a first side spaced apart from an opposed second side in the translation direction; and wherein the plane reciprocally translates within the holding area between the first side and the second side.

44. The surgical planer of claim 45, wherein the plane has a first edge spaced apart in the translation direction from an opposed second edge by a length LP; wherein when measured in the translation direction the first side of the holding area is displaced from the second side by a length LH; wherein the distance the plane reciprocally translates in a revolution of the drive shaft is less than or equal to result of the calculation LH - LP such that the plane reciprocally translates within the holding area between the first side and the second side.

45. The surgical planer of any one of claims 38 to 46, wherein relative to the plane the plane reciprocally translates a displacement which is twice the radius measured from the drive shaft axis to a point on a or the pin used to couple the drive shaft to the plane that is the maximum distance from the drive shaft axis.