WO1998046152A1

WO1998046152A1 - Long bone reamer

Info

Publication number: WO1998046152A1
Application number: PCT/US1997/006138
Authority: WO
Inventors: Allan S. Frieze; David Nalepa
Original assignee: Case Medical, Inc.
Priority date: 1997-04-14
Filing date: 1997-04-14
Publication date: 1998-10-22
Also published as: AU2667097A

Abstract

A long bone reamer apparatus (10, 100) is assembled from a plurality of blades (18, 150) that interlink with each other. According to a first embodiment (10), six long cutting blades (18) are held in position by a plurality of disks (20), each having six blade receiving slots (60) spaced at 60° with respect to each other. The longitudinal axis (64) of each of the blade receiving slots (60) is slightly offset from the center (62) of the disk (20) so that tabs (30a, 30b, 42a, 42b, 54a, 54b) on opposing blades (22a, 22b, 34a, 34b, 46a, 46b) contact and are welded to each other. According to a second preferred embodiment (100) of the invention, four blades are connected together in a boxlike arrangement having a long rod-like (140, 150) means in the center thereof for support. A first set of said blades (110a, 110b) includes an interior aperture (112a, 112b) with a plurality of tabs (120a, 120b) which engage with a plurality of tab receiving slots (138a, 138b) in the second set of blades (130a, 130b). Both sets of reamers (10, 100) have a head (12, 102) with blade portions (26a, 26b, 38a, 38b, 50a, 50b, 114a, 114b, 132a, 132b) arranged to lie along the surface of a semi-circle and, moreover, both embodiments (10, 100) have longitudinal sidewalls (14, 104) having cutting edges (24a, 24b, 36a, 36b, 48a, 48b, 116a, 116b, 134a, 134b), which lie in the plane of a cylinder.

Description

TITLE: LONG BONE REAMER

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to surgical long bone reamers formed from a plurality of interlocking blades.

2. Descnption of Related Art

The pπor art patent literature discloses a small group of reamers and cutters for removing bone and tissue from joints that may be relevant to the state of the art Many of those reamers are for shallow bone applications. For example, U.S. Patent 4,621,637 entitled "SURGICAL DEVICE FOR REMOVING BONE AND TISSUE FROM JOINT MEMBERS" teaches a slotted, surgical device including a hemispheric housing that supports one or more cutting blades for bone and/or tissue cutting. Two and three blade embodiments are described. In both cases, the blades abut centrally of the device and interlock with the base at discrete points.

French Patent 1,031,888 descπbes a plurality of cutting blades which are radially disposed, eq angularly spaced atop a supporting plate and locked to the plate by fasteners The resulting tool is used for cutting the acetabular portion of a hip prior to joint replacement Similarly, French Patent 1,041,311 descπbes a bone cavity forming tool which employs multiple blades in a hemispheπc array.

Soviet Union Patent 1225-543-A entitled "BONE CUTTING TOOL FOR SURGERY" descπbes a cutter compπsmg multiple arcuate cutting elements extending from a central rod outwardly in an umbrella-like fashion. French Patent 2,233,972 entitled "ARTIFICIAL HIP JOINT FITTING

EQUIPMENT" descπbes another multi-blade, round headed milling cutter for acetabular applications.

U.S. Patent 5,222,959 entitled "REMOVAL OF TISSUE" describes a soft tissue cutter having an oval, rather than hemispheπc, shape. U.S. Patent 5,192,291 entitled "ROTATIONALLY EXPANDABLE

ATHERECTOMY CUTTER ASSEMBLY" descπbes another soft tissue cutter in which the blades define a cylindrical, not hemispheric, structure. U.S. Patent 5,100,267 entitled "DISPOSABLE ACETABULAR REAMER CUP" describes a hemispheric, cup-shaped hip reamer With regard to this structure, note also U S Patents 5,116,165 and 5,376,092.

The following U.S Patents descπbe prior art shallow bone reamers of possible interest, using multi-blade configurations, but for non-hip applications 3,554,192, 5,122,134,

5,180,384 and 5,318,576.

In addition to shallow bone reamers, the prior art also discloses a few possibly relevant references to long bone reamers. For example, note U S Patent 4, 473,070 entitled

INTRAMEDULLARY REAMER That device includes a circular, replaceable blade that fits onto a grooved body member There does not appear, however, to be any suggestion of interlinking or cross over blades.

U.S Patent 314,086 entitled BUNG CUTTER is of possible interest even though it does not relate to bone surgery. That references describes a structure including a mortised disk which rotates into position and includes a plurality of longitudinally extending cutters which seat in the disk via notches or mortises F on the periphery thereof The structure, however, appears to relate primarily to cutting a bung hole in a barrel rather than reaming a hole therethrough

The following patents are all cited as being of general interest only and are essentially the same in that they descπbe a reamer head for a long bone The blades appear to generally radiate from a central portion and do not appear to be interlinked 3,554,192, 4,706,659,

5,122,134; and, 5,190,548.

Lastly, U.S. Patent 3,633,583 entitled ORTHOPEDIC SINGLE-BLADE BONE CUTTER and U.S. Patent 5,211,645 entitled DEVICE FOR GUIDING AN INTERNAL SAW FOR LONG TUBULAR BONE OSTEOTOMY are cited as being as general relevance only.

While a few long and shallow joint reamers are known m the pπor art, they tend to be expensive, or hard to construct, or both. There clearly appears to be a need for a safe, easy to assemble, inexpensive and effective reamer especially for the femur or tibia Insofar as understood, none of the pπor art known to the inventor, whether taken individually or m combination, hints, teaches or suggests the novel long bone reamer disclosed herein

SUMMARY OF THE INVENTION Briefly descπbed, the invention compπses a long bone reamer including a plurality of interlinking cutting blades which, when assembled, has a cutting head or tip with a cutting edge which lies in a hemispheπcal plane According to a first embodiment of the invention, the reamer compπses six blades each having a straight, long side and a curved tip. The six blades are held in position by a plurality of disks each having six blade receiving slots therein. Each blade also includes an inside surface having a plurality of tabs which, when assembled on the disks, overlap each other. The six blades actually compπse three sets of two blades each wherein the tabs of each of the three sets are offset so that they don't interfere with each other When properly assembled, each of the tabs of the three sets of blades overlap each other and may be welded in that position.

According to a second embodiment of the invention, four blades are assembled m a boxlike structure to form the long bone reamer Two sets of blades include a hollow aperture with inwardly facing tabs thereon, which mate with coπespondmg slots in the second set of blades A rod or similar structure is located in the hollow interior of the boxlike structure for additional support.

When properly assembled, each of the two embodiments has edges which when rotated, all he in a semi-circular surface. Moreover, when each of the embodiments is rotated, the longitudinal cutting edges of each of the blades he in a cyhndπcal plane The resulting structure is safe, easy to assemble, inexpensive and effective as a long bone reamer

The invention may be more fully understood by reference to the following drawings BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of a large diameter, long bone reamer according to a first embodiment of the invention.

Fig. 2 is an exploded perspective view of the large diameter, long bone reamer of Fig 1.

Fig. 3 A is a front view of the large diameter, long bone reamer of Fig. 1 Fig. 3B is a rear view of the large diameter, long bone reamer of Fig. 1

Fig. 3C is a side view of the large diameter, long bone reamer of Fig. 1. Fig. 3D is a cross sectional view of the large diameter, long bone reamer of Fig 3C as seen from perspective 3D - 3D.

Fig 4A illustrates one blade of the first set of blades of the large diameter, long bone reamer of Fig. 1.

Fig. 4B illustrates one blade of the second set of blades, of the large diameter, long bone reamer of Fig. 1.

Fig. 4C illustrates one blade of the third set of blades of the large diameter, long bone reamer of Fig. 1. Fig. 5 is a front view of one of the supporting disks of the large diameter, long bone reamer of Fig. 1 showing the six blade receiving slots therein.

Fig. 6 is a perspective view of a small diameter, long bone reamer according to the preferred second embodiment of the invention. Fig. 7 is an exploded view of the small diameter, long bone reamer of Fig. 6

Fig. 8A is a front view of the small diameter, long bone reamer of Fig. 6. Fig. 8B is a rear view of the small diameter, long bone reamer of Fig. 6 Fig. 8C is a side elevational view of the small diameter, long bone reamer of Fig 6 Fig. 9A is a top plan view of one of the two blades of the first set of blades included in the small diameter, long bone reamer of Fig. 6.

Fig. 9B is a top plan view of one of the two blades of the second set of blades included in the small diameter, long bone reamer of Fig 6.

Fig. 10 illustrates the supporting and locking rod having a round cross section which goes down the center of the small diameter, long bone reamer. Fig. 11 illustrates an alternative supporting and locking rod having a square cross section.

Fig. 12 illustrates a cylindrical reamer having cutting teeth on the leading edge thereof

DETAILED DESCRIPTION OF THE INVENTION During the course of this descπption, like numbers will be used to identify like elements according to the different figures that illustrate the invention.

A large diameter long bone reamer 10 according a first embodiment of the invention is illustrated in Fig. 1. Each reamer 10 includes a rounded, hemispheπcal head 12, a plurality of blade edges 14 which e in a cylmdπcal plane and a rear portion 16. Six long blades 18 are held in assembled position by disks 20. The six blades 18 are formed from three sets of two matching blades each. The first blade pair compπses blades 22a and 22b; the second blade pair comprises blades 34a and 34b and the third pair of blades compnses blades 46a and 46b. Details of the blades are shown in Figs. 4A, 4B and 4C.

Fig. 4A illustrates blade 22a of pair 22a and 22b. Blade 22b is substantially identical to 22a Blades 22a and 22b each include a straight, longitudinal cutting edge 24a and 24b, a rounded cutting tip 26a and 26b, an inside edge 28a and 28b; tabs 30a and 30b located on the mside edges 28a and 28b; and a rear edge 32a and 32b. Likewise, blade 34a is illustrated m Fig 4B but is substantially identical to its mating blade 34b Blades 34a and 34b are similar, but not identical, to blades 22a, 22b, 46a and 46b. In particular, blades 34a and 34b each include a straight, longitudinal cutting edge 36a and 36b, a rounded cutting tip 38a and 38b, an mside edge 40a and 40b; tabs 42a and 42b located on the mside edge 40a and 40b, and a rear edge 44a and 44b Note that tabs 42a are offset with respect to the relative position of tabs 30a on blade 22a as shown in Fig. 4A. Lastly, blade 46a of blade pair 46a and 46b, is illustrated in Fig. 4C. Blade 46a is substantially identical to blade 46b Both blades 46a and

46b each include a straight, longitudinal cutting edge 48a and 48b; a rounded cutting tip 50a and 50b; an mside edge 52a and 52b; tabs 54a and 54b located on the mside edges 52a and 52b, respectively; and, a rear end 56a and 56b. Tabs 54a and 54b are aligned to match with each other but are offset so that they do not align with tabs 42a and 42b of the first pair of blades 34a and 34b; nor do they align with tabs 30a and 30b of the first pair of blades 22a and

22b

Blades 18 (22a, 22b, 34a, 34b, 46a and 46b) are received in slots 60 of the disks 20 illustrated in Fig 5 Disks 20 have a center point 62 and each of the slots 60 has a major axis 64 Each axis 64 is slightly offset from disk center 62 so that tabs 30a, 30b, 42a, 42b, 54a and 54b overlap but do not interfere with each other.

When the apparatus 10 is assembled, the front tip 12 appears as shown in Fig 3a and the rear end 16 appears as shown m Fig. 3B. Fig 3D is a cross-sectional view of the assembled reamer 10 as illustrated in Fig. 3C and as seen from perspective 3D - 3D Note that tabs 54a and 54b of blades 46a and 46b overlap and touch each other They are preferably welded in this position. In a similar fashion, tabs 30a and 30b of blades 22a and

22b overlap each other as do tabs 42a and 42b of blades 34a and 34b To achieve this structure, slots 60 have a long access 64 that when extended slightly misses the center 62 of the disks 20 so that the tabs 30a, 30b, 42a, 42b and 54a and 54b slightly overlap each other and do not interfere Tabs 30a, 42a, 54a are preferably welded respectively to tabs 30b, 42b and 54b

When the apparatus 10 is assembled, the cutting tips 26a, 26b, 38a, 38b and 50a and 50b have edges which he essentially the same rounded, hemispheπcal plane so that the reamer 10 is rotated it cuts smoothly and evenly into the bone. Likewise, the sidewall 14 compπses the exteπor long, straight cutting edges 24a, 24b, 36a, 36b, 48a and 48b all of which he m the same, round cylindrical plane so that the reamer 10 is rotated, it cuts smoothly The tabs may be welded to each other and/or disks 20 in order to keep the device m a permanent, assembled state. The foregoing reamer is especially useful for large diameter, long bones The interlinking of the blades gives the structure additional πgidity In addition, it is relatively easy to manufacture and assemble and, therefore, it is inexpensive to distribute to the public

Fig 6 illustrates the second or preferred embodiment 100 of a small diameter, long bone reamer The small diameter, long bone reamer 100 includes a cutting head 102, a cutting sidewall 104 and a rear end 106

Fig 7 illustrates the small diameter, long bone reamer 100 in an exploded view Reamer 100 includes a group of four blades 150 divided into two sets or pairs The first pair of blades m the group 150 compπse elements 110a and 110b, the second pair of blades in the group 150 comprise elements 130a and 130b A central rod 140 is received in the boxlike cavity formed by the blades and serves to give additional πgidity to the resulting structure

Blade 110a is illustrated m detail in Fig 9 A Blade 110a is substantially identical to blade 110b and lies on the opposite side of the apparatus 10 from blade 110a Blade 110a includes an inteπor cavity 112a, a rounded cutting tip 114a, a straight, longitudinal cutting edge 116a, a rear end 118a, and a plurality of inward facing tabs 120a along the two long edges 122a of the inteπor cavity 112a

Fig 9B illustrates blade 130a in detail Blade 130a is substantially identical to blade 130b and includes a partially rounded cutting tip 132a, a long, straight, cutting edge 134a, a rear end 136a, and a plurality of tab receiving slots 138a Slots 138a receive the tabs 120a and 120b of blades 110a and 110b of the first set

The small diameter, long bone reamer 100, as seen in profile in Fig 8C, is assembled in the following manner First, the two blades 110a and 110b are placed side by side Second, blade 130a is placed between the two blades 110a and 110b in such a way that tabs 120a and 120b engage the tab receiving slots 138a Third, blade 130b is placed between blades 110a and 110b and has its slots 138a engaged with the remaining tabs 120a Fourth, rod 140 is placed down the middle of the structure to keep the blades 130a and 130b in position with respect to the tabs on blades 110a and 110b When properly assembled, the cutting head 102 appears as shown in Fig 8 A and the rear 106 of the device appears as shown in Fig 8B The central rod 140 is illustrated in Fig 10 When the small diameter, long bone reamer 100 is assembled as shown in Figs 6, 7 and 8C, the tips 114a, 114b, 132a and 132b have points which define a rounded, semi-circular form such that when the reamer 100 is rotated it cuts evenly and smoothly Similarly, the cutting edges 116a, 116b, 134a and 134b define eight cutting edges which he in a generally cy ndπcal plane such that when the reamer 100 is rotated it cuts smoothly The small diameter, long bone reamer 100 is somewhat different in structure from the large diameter, long bone reamer 10 because the dynamics of the cutting operation in a small bone are different from the dynamics of the cutting operation in a long bone Four cutting blades 110a, 110b, 130a and 130b are required for the small diameter, long bone reamer because there isn't room to fit additional blades. In contrast, the large diameter, long bone reamer 10 has more room and, therefore, can accommodate six blades 18, namely blades 22a, 22b, 34a, 34b, 46a and 46b.

The small diameter, long bone reamer 100 according to the preferred embodiment of the invention is very strong, especially given the central support of rod 140; is relatively easy to manufacture; and, relatively inexpensive to distπbute.

Long bone reamer 100 can be modified to achieve different performance characteπstics. First of all, the round rod 140 shown in Fig. 10 can also have a square cross section as shown by rod 150 in Fig 11. A square rod 150 produces a more rigid reamer 100 and also helps to keep debris out of the middle channel of the apparatus. It has also been found that if the square rod is welded at just one location to the blade package that the reamer apparatus 100 becomes relatively flexible - a characteristic that is desirable if a femur or tibia is curved. It is also possible to replace the metal rod 140 or 150 with a high temperature plastic rod for additional flexibility and ease of cleaning.

The four blade second embodiment 100 is preferred over the six blade first embodiment 10 because it is easier to construct the four blade embodiment 100 m smaller diameter sizes. While the small diameter reamer 100 preferably has four blades it would be possible to use the same interlocking concept to construct a reamer 100 with 4, 6, 8, 10 blades, etc

Lastly, it may be desirable to add teeth to the leading edge of reamer 10 (or reamer 100) so that the reamer 10 can both drill and ream. Fig 12 illustrates such a reamer 200 having teeth 202 on its leading edge 12.

While the invention has been descπbed with respect to the preferred embodiment thereof, it will be appreciated by those of ordinary skill in the art that various modifications can be made to the structure and function of the invention without departing from the spiπt and scope thereof.

Claims

WE CLAIM:

1. A long bone reamer apparatus (10, 100, 200) comprising: a plurality of N long blades (18, 150), each blade, (22a, 22b, 34a, 34b, 46a, 46b, 110a, 110b, 130a, 130b) having a long, relatively straight cutting edge (24a, 24b, 36a, 36b, 48a, 48b, 116a, 116b, 134a, 134b) and a partially rounded leading cutting tips (26a, 26b,

38a, 38b, 50a, 50b, 114a, 114b, 132a, 132b); and, holding means (20, 120a, 120b, 138a, 138b, 140) for holding said blades (22a, 22b, 34a, 34b, 46a, 46b, 110a, 110b, 130a, 130b) together, wherein said reamer apparatus (10, 100) when assembled has a head portion (12, 102) with cutting tips (26a, 26b, 38a, 38b, 50a, 50b, 102a, 102b, 132a, 132b) that e in a semi-circular plane, and a side portion (14, 104) with said cutting edges (24a, 24b, 36a, 36b, 48a, 48b, 116a, 116b, 134a, 134b) that he in a cylindrical plane.

2 The apparatus of claim 1 wherein N equals at least three.

3. The apparatus of claim 2 wherein N equals at least four 4. The apparatus of claim 3 wherein said holding means comprises a plurality of disks (20) each having a plurality of blade receiving slots (60) therein

5. The apparatus of claim 4 wherein each blade (22a, 22b, 34a, 34b, 46a, 46b) has a plurality of tabs (30a, 30b, 42a, 42b, 54a, 54b) on side of said blade (28a, 28b, 40a, 40b, 52a, 52b) opposite from said side long, relatively straight cutting edge (24a, 24b, 36a, 36b, 48a, 48b), wherein said tabs (30a, 30b, 42a, 42b, 54a, 54b) of opposing blades contact and support each other.

6 The apparatus of claim 5 wherein N equals 6 and said blade receiving slots

(60) in said disk are spaced approximately 60° with respect to each other 7. The apparatus of claim 6 wherein said blade receiving slots (60) have a long axis (64) that bypasses the center (62) of said disks (20) so that said tabs (30a, 30b, 42a, 42b, 54a, 54b) can overlap without interfeπng with each other

8. The apparatus of claim 3 wherein said apparatus further compπses- a first set of blades (110a, 110b) each including an aperture (112a, 112b) therein, a pair of long opposing internal sides (122a, 122b), each internal side (122a, 122b) including a plurality of tabs (120a, 120b) thereon; and, a second set of blades (130a, 130b) having a plurality of tab receiving slots (138a, 138b) therein; wherein said first (110a, 110b) and second (130a, 130b) set of blades have cutting edges (116a, 116b, 134a, 134b) on the sides thereof.

9. The apparatus of claim 8 further including a rod (140) means locatable on the mside of said reamer apparatus (100) for keeping said blades (110a, 110b, 130a, 130b) in an assembled condition.

10. The apparatus of claim 9 wherein said rod (140) has a round cross section

11. The apparatus of claim 9 wherein said rod (150) has a square cross section

12 The apparatus of claim 9 wherein said rod (140, 150) is formed by high temperature resistant plastic. 13 The apparatus of claim 9 wherein said rod (140, 150) is welded in at least one location to at least one of said blades (110a, 110b, 130a, 130b).

14. The apparatus (200) of claim 3 wherein said partially rounded cutting tips include teeth (202) thereon.

AMENDED CLAIMS

[received by the International Bureau on 8 August 1997 (08.08.97) original claim 4 cancelled; original claims 1,5,8 and 14 amended; new claim 15 added; remaining claims unchanged (2 pages)]

1. A long bone reamer apparatus (10, 200) comprising: a plurality of N long blades (18), each blade, (22a, 22b, 34a, 34b, 46a, 46b) having a long, relatively straight cutting edge (24a, 24b, 36a, 36b, 48a, 48b) and a partially rounded leading cutting tip (26a, 26b, 38a, 38b, 50a, 50b); and, holding means (20) for holding said blades (22a, 22b, 34a, 34b, 46a, 46b) together, said holding means comprising a plurality of disks (20) each having a plurality of blade receiving slots (60) therein. wherein said reamer apparatus (10, 200) when assembled has a head portion (12) with cutting tips (26a, 26b, 38a, 38b, 50a, 50b) that lie in a semi-circular plane, and a side portion (14) with said cutting edges (24a, 24b, 36a, 36b, 48a, 48b) that lie in a cylindrical plane.

2. The apparatus of claim 1 wherein N equals at least three.

3. The apparatus of claim 2 wherein N equals at least four.

5. The apparatus of claim 3 wherein each blade (22a, 22b, 34a, 34b, 46a, 46b) has a plurality of tabs (30a, 30b, 42a, 42b, 54a, 54b) on side of said blade (28a, 28b, 40a, 40b, 52a, 52b) opposite from said side long, relatively straight cutting edge (24a, 24b, 36a, 36b, 48a, 48b), wherein said tabs (30a, 30b, 42a, 42b, 54a, 54b) of opposing blades contact and support each other.

6. The apparatus of claim 5 wherein N equals 6 and said blade receiving slots (60) in said disk are spaced approximately 60° with Tespect to each other.

7. The apparatus of claim 6 wherein said blade receiving slots (60) have a long axis (64) that bypasses the center (62) of said disks (20) so that said tabs (30a, 30b, 42a, 42b, 54a, 54b) can overlap without interfering with each other.

8. A long bone reamer apparatus (100) comprising: a plurality of N long blades (150), where N equals at least four, each blade (110a, 110b, 130a, 130b) having a long, relatively straight cutting edge (116a, 116b, 134a, 134b) and a partially rounded leading cutting tip (114a, 114b, 132a, 132b), said plurality of N long blades including a first set of blades (HOa, 110b) each including an aperture (112a, 112b) therein, a pair of long opposing internal sides (122a, 122b), each internal side (122a, 122b) including a plurality of tabs (120a, 120b) thereon, and, a second set of blades (130a, 130b) having a plurality of tab receiving slots (138a, 138b) therein, wherein said first (110a, 110b) and second (130a, 130b) set of blades have cutting edges (116a, 116b, 134a, 134b) on the sides thereof; and, holding means (120a, 120b, 138a, 138b, 140) for holding said blades (110a, 110b, 130a, 130b) together, wherein said reamer apparatus (100) when assembled has a head portion (102) with cutting tips (102a, 102b, 132a, 132b) that lie in a semi-circular plane, and a side portion (104) with said cutting edges ( 116a, 116b, 134a, 134b) that lie in a cylindrical plane.

9. The apparatus of claim 8 further including a rod (140) means locatable on the inside of said reamer apparatus (100) for keeping said blades (110a, 110b, 130a, 130b) in an assembled condition.

10. The apparatus of claim 9 wherein said rod (140) has a round cross section.

11. The apparatus of claim 9 wherein said rod (150) has a square cross section.

12. The apparatus of claim 9 wherein said rod (140, 150) is formed by high temperature resistant plastic.

13. The apparatus of claim 9 wherein said rod (140, 150) is welded in at least one location to at least one of said blades (110a, 110b, 130a, 130b).

14. The apparatus (200) of claim 1 wherein said partially rounded cutting tips include teeth (202) thereon.

15. The apparatus ( 100) of claim 8 wherein said partially rounded cutting tips include teeth thereon.