Apparatus for distracting or compressing longitudinal bone segments

Abstract

An orthopedic apparatus for selectively distracting or compressing contiguous longitudinal bone segments comprising a first and second support member each of which can be placed longitudinally coextensively adjacent respective bone segments. A first longitudinal bore extends within the first support member for receiving and threadably engaging one portion of a threaded driving rod, and a second longitudinal bore, axially aligned with the first longitudinal bore, extends within the second support member for receiving and threadably engaging another portion of the threaded driving rod. Upon rotation of the threaded driving rod the first and second support members are longitudinally simultaneously adjusted. The apparatus can be inserted into the limb according to standard orthopedic surgical procedures and then mounted adjacent the bone segments after which the support members are periodically adjusted to stimulate the growth of new bone matter between the distracted bone segments. A method for distracting longitudinal bone segments by insertably mounting an adjustable distracting apparatus adjacent longitudinal bone segments and periodically adjusting the apparatus to stimulate a build up of new bone growth between the bone segments.

Description

BACKGROUND OF THE INVENTION

This invention relates to an orthopedic apparatus for distracting or compressing contiguous longitudinal bone segments whereby the apparatus is releasably mounted immediately adjacent the bone segments within the limb. Reference may be made to the following U.S. patents: U.S. Pat. Nos. 1,997,466, 2,024,325, 2,101,889, 2,204,266, 2,238,869, 2,250,417, 2,317,519, 2,391,537, 2,393,694, 2,393,982, 2,687,720 and 3,547,113.

There are known orthopedic surgical procedures, see for example, U.S. Pat. No. 3,547,113, for lengthening a bone, such as the tibia, whereby one of two bone fixation pins is inserted through the limb and bone on either side of the desired bone breaking point. The bone is broken between the pins and a support member is attached to the ends of each fixation pin outside the limb. The support members are then periodically adjusted by means of a threaded connecting rod until the desired distracted bone length is attained. A cast is applied around the limb and pins to hold the bone segments in a substantially axially aligned position and the outside support members are then detached from the pins.

The prior art devices cause many surgical and post operative problems because of their inherent structural deficiencies. None of the prior art devices presently in use or previously mentioned adequately hold the distracted bone segments in rigid axial alignment, because the rigidity of the connection between the support apparatus is dependent upon the rigidity of the bone fixation pins. Thus, not only is angulation and rotation of the bone segments difficult to control when these prior art devices are used, but there is also an increased chance of infection in the open wounds surrounding the pins and pressure necrosis of the skin adjacent the pins. The use of a cast has the disadvantages of causing the patient general discomfort and delaying the time within which the distracted limb may be therapeutically exercised to alleviate muscular tightening, muscle atrophy, and joint stiffness.

SUMMARY OF THE INVENTION

According to the present invention, an apparatus is provided of a size for implantation within a limb in direct contact with a bone for selectively positioning, i.e., distracting or compressing contiguous longitudinal bone segments, comprising a first elongated support member and a second elongated support member, each having means for placement longitudinally coextensively adjacent a respective bone segment. The first and second support members are operatively connected together for adjusting the longitudinal displacement between each support member and for preventing rotational movement of the first and second support members during the longitudinal movement thereof and each have means for releasable attachment immediately adjacent their respective bone segments.

The apparatus is surgically placed within the limb and mounted immediately adjacent the bone segments. The support members may then be periodically adjusted to distract or compress the bone segments.

The invention not only prevents angulation and rotation of the bone segments, but also eliminates the need for a post operative cast, since the bone segments are rigidly held in place by the support members in an axially aligned position. Therefore, there is no chance of infection due to pin tract wounds in the limb, and rehabilitation of the limb may be commenced soon after the operation. The apparatus is lightweight and simple in design, and may be constructed to accommodate almost any bone size.

Other advantages of the invention will become apparent to those skilled in the art upon reading and understanding the further detailed description of this invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the preferred apparatus embodiment of the invention in a closed position and mounted on illustrated bone segments within a limb;

FIG. 2 is a top view of the apparatus of FIG. 1 shown in the partially opened position with new bone growth formed between the bone segments;

FIG. 3 is an end sectional view along line 3--3 of FIG. 1 with the limb shown in phantom lines;

FIG. 4 is a front sectional view along line 4--4 of FIG. 2;

FIG. 5 is a perspective view of a second apparatus embodiment of the invention in an opened position;

FIG. 6 is an end sectional view along line 6--6 of FIG. 5;

FIG. 7 is a rear sectional view along line 7--7 of FIG. 6;

FIG. 8 is a front view of a third apparatus embodiment of the invention in a closed position;

FIG. 9 is an end sectional view along line 9--9 of FIG. 8;

FIG. 10 is a top view of the apparatus of FIG. 8;

FIG. 11 is a perspective view of the apparatus of FIG. 8 in an open position;

FIG. 12 is a front sectional view along line 12--12 of FIG. 11 showing the pawl mechanism in a closing position;

FIG. 13 is a front sectional view along line 12--12 of FIG. 11 showing the pawl mechanism in an opening position; and,

FIG. 14 is an exploded perspective view of the pawl mechanism.

DETAILED DESCRIPTION adaptable

Referring initially to FIGS. 1-4, the preferred apparatus embodiment of the invention is shown generally at 5 and is releasably mounted to bone 4 within a limb (see FIG. 3), comprising a first or proximal longitudinal bone segment 18, and a second or distal longitudinal bone segment 22. For purposes of example, reference will be made to the distraction of the femur bone although it will become apparent to those skilled in orthopedic surgery that the invention is adaptable to be used on any relatively long bone and for either distraction or compression, as desired.

As shown in FIGS. 1-4, the apparatus includes a pair of elongated support members 6 and 8. Each support member comprises a rectangular block of stainless steel that has a concave rear surface 52 which permits each support member to lie immediately adjacent to each respective bone segment.

Screws or pin members 14 may be used to releasably mount the apparatus to femur bone 4 through a plurality of screw holes or apertures 15 in support members 6 and 8. Although the size of the screws may vary according to the size of the apparatus and bone, screws having a diameter of 0.164 inches and a suitable length are recommended so that the apparatus is firmly secured to each of the femur bone segments. Other means for mounting the support members may be utilized, as long as each support member is securely mounted to the bone segments.

Support members 6 and 8 are rigidly adjustably connected together by driving rod 10 and guiding rod 12. Driving rod 10 not only imparts longitudinal movement to the support members but also maintains substantial longitudinal alignment of the first and second support members. Driving rod 10 comprises oppositely threaded and axially aligned sections 40 and 43, which are engageable with similarly oppositely threaded bores 44 and 46, extending within support members 6 and 8. Bore 44 has an internal left-handed thread corresponding to section 40 of rod 10, and bore 46 has an internal right-handed thread corresponding to section 42 of rod 10. This feature permits second support member 8 to move or impart bone segment 22 a longitudinal distance in the direction of arrow 1 in response to the rotational movement of driving rod 10.

Smooth guiding rod 12 is mounted or fixed within bore 48 in support member 6, and the opposite portion of guiding rod 12 is slidably engageable or mounted within bore 50 in support member 8. Guiding rod 12 gives the apparatus rigidity as it is adjustably opened or closed by preventing rotational movement of the first and second support members during the longitudinal movement thereof and maintains each support member in constant axial alignment, thereby eliminating angulation and rotation of the bone segments. Fluid drainage holes 56 are interspaced along the top of each support member.

Small threaded pin or screw 9 is threadably screwed into bore 11, in socket head 26, of rod 10 and is then screwed into bone segment 18 after the apparatus is adjusted to insure that the distracted distance remains constant.

In use as a distraction device, the apparatus is inserted into the limb adjacent the bone segments and distraction is accomplished in periodic adjustments to position the bone segments as desired, thereby enabling the formation of new bone growth 54 between the bone segments. The method of distracting the bone segments is hereinafter described in more detail.

FIGS. 5-7 show a second apparatus embodiment of the present invention, comprising first and second elongated support members 60 and 62 that are rigidly adjustably connected by means of threaded driving rod 58 and smooth guiding rod 82. Guiding rod 82 is connected to support members 60 and 62 in the same manner as shown in the previously described preferred apparatus embodiment and prevents rotational movement of the support members during the longitudinal movement of second support member 62. An internally threaded bore 64 extends within support member 62 for engagement with one end portion of driving rod 58; and smooth bore 66, axially aligned with threaded bore 64, extends within support member 60 for receiving another end portion of rod 58.

End 71 of driving rod 58 is mounted to beveled gear 72 for engagement with beveled gear 74 which is rotatably mounted in, bushing 76 within support member 60 (see FIGS. 6 and 7). When gear 74 is rotated gear 72 rotates which in turn moves or imparts longitudinal movement to support member 62 in the direction of arrow 61.

FIGS. 8-14 show a third embodiment of the invention wherein support members 91 and 93 comprise first portions, 92 and 94 and L-shaped second portions 96 and 98, respectively, extending a distance b from bone 4 (see FIG. 9). Second portions 96 and 98 are slidably connected to each other and are operatively connected to each other by means of a rack and pinion mechanism. The interconnection of second portions 96 and 98 inherently prevents support members 91 and 93 from rotating during the longitudinal movement thereof. The rack and pinion mechanism comprises a driving gear pinion 108 having a wrench receiving aperture 111. Arms 96 and 98 have slots 107 and 109 for first and second gear racks 103 and 105, respectively. Thus, as shown in FIG. 8, pinion 108 is locked within arms 96 and 98 and is simultaneously operatively engageable with gear racks 103 and 105. Support member 94 will longitudinally move or impart in the direction of arrow 117 (see FIG. 11) when pinion 108 is rotated in the direction of arrow 115.

A pawl and gear rack mechanism is shown in FIGS. 12-14 which restricts the longitudinal displacement of the support members in a first set of opposed directions while preventing longitudinal movement in a second set of opposed directions opposite the first set. The pawl mechanism comprises a pawl 118 having a flange 120 and a shank 122. The shank is inserted into spring 124. Cylindrical housing 126 contains slots 128 and 129 for receiving flange 120, and is threaded at 127 for insertion into bottom surface 113 of housing 112. Gear rack 119 is machined out of the bottom surface of arm 98 (see FIGS. 12 and 13). Thus, pawl 118 is held in a biased position against rack 119 when housing 126 is screwed into position within housing 112. FIGS. 12 and 13 respectively show the adaptability of the pawl mechanism to be mounted in housing 126 in a first position in which the biased engagement of pawl 118 against rack 119 permits converging longitudinal movement of the support members while preventing diverging longitudinal movement therof, and in a second position in which the biased engagement of pawl 118 against rack 119 prevents converging longitudinal movement while permitting diverging longitudinal movement thereof.

In FIG. 12, flange 120 is inserted into slot 129 so that the support members may simultaneously converge towards pinion 108. FIG. 13, shows flange 120 inserted and, in slot 128 thus permitting the support members to simultaneously diverge away from pinion 108.

Adaptable with all of the embodiments is a follower apparatus 28, as shown in use with the third apparatus embodiment in FIG. 10 and 11, that may be used to increase the rigidity of the coupled bone segments. Follower plate 28 is attached to the medial side of the bone by using longer screws 95. If the follower is used, onlay graft 24 may be placed on the top of the bone, as shown in FIGS. 8, 10, and 11.

It is to be noted that all of the apparatus embodiments may be used to reduce fractures by simply closing the support members until the fractured segments of bone are joined by compression.

Referring, for example, to the preferred embodiment of FIGS. 1-4, the method of using the invention for distraction comprises the steps of attaching the proximal or first support member 6 to proximal bone segment 18. Onlay graft 24 is not mounted to the bone until after the bone is broken and both support members are in place. Bone 4 is then cut in a step-cut fashion or may be drilled in a transverse direction, and then fractured. Care is taken while fracturing the bone to prevent the tearing of the periosteum. The periosteum is split longitudinally and incised circumferentially at the distal end of the incision to form a split sleeve of periosteum; thus, periostial growth of new bone is not endangered. The distal or second support member 8 is clamped to the distal bone segment after the bone is broken, and the bone segments are then manually axially aligned to correct angulation and rotation of the bone segments which occurs after the bone is broken. Once the bone segments are aligned, the second support member is mounted to distal bone segment 22 in the same manner as the first support member was mounted to proximal bone segment 18.

To insure complete and rapid ossification of bone segments 18 and 22, an onlay graft 24 is taken from the fibula and/or ileum during the operation and is loosely affixed to bone segment 4 by using longer screw 20 (see FIG. 3). The onlay graft is mounted on the medial side of bone 4 bridging gap 3 between bone segments 18 and 22 after the apparatus is adjusted. The onlay graft will become incorporated into new bone growth 54 as the bone ends are completely joined by callus. Screw 20 may be placed in any of the pin receiving apertures 15, but is preferably placed in the second opening of support member 6.

After onlay graft 24 is affixed to the bone, the apparatus is adjustably opened by rotating rod end 26 with a screwdriver or the like, until the apparatus and bone segments are distracted approximately three/fourths inch to 1 inch. Onlay graft 24 will slide along the medial side of the bone as shown in FIG. 2. The wound in the limb is then closed according to standard surgical techniques. After a week to ten days, a small incision is made in the limb over the rod end and rod 10 is rotated again, thereby opening the apparatus another one/fourth inch to one/eight inch. This procedure may be repeated about every 10 days over a period of 3 to 6 weeks until a maximum distraction of approximately 2 inch to 2 1/2 inch is effectuated. The purpose of this periodic adjustment is to insure that the gradual build up of callus or new bone growth 54 will be maintained between the bone segments. Each time the apparatus is adjusted, the newly formed callus is broken up and new callus growth is stimulated. There are some cases, however, in which it may be desirable, in addition to using an onlay graft(s), to fill the gap between the bone segments with cancellous bone grafts in the form of chips.

After the initial operation, the patient may be placed in traction because a cast need not be used. The traction relieves the pressure that the lengthened bone exerts against the knee and hip socket. Note, however, that the apparatus is suitable for use even if a cast is used. While in traction, the patient may exercise the lower portion of the leg in order to further alleviate the socket pressure and to stretch the tight muscles. After the patient is taken out of traction, the limb is placed within a brace until complete ossification of the bone has occurred. The brace will relieve any undue stress on the apparatus and on the new bone before complete bone union occurs. The bone ends will be completely joined after six months to one year. The apparatus and brace may then be removed as soon as a new medullary canal forms.

It is to be noted that the present invention is susceptible to dimensional change depending upon the size of the bone to be distracted. It will be understood that the particular embodiments illustrated and described represent the best form of the invention presently known, and that the invention is not intended to be limited to the particular details so illustrated and described, but encompasses all embodiments falling within the scope of the appended claims.

Claims

What is claimed is:

1. An orthopedic apparatus of a size for implantation within a limb in direct contact with a bone for selectively positioning contiguous longitudinal bone segments, said apparatus comprising:

a first elongated support member;

a second elongated support member;

means on said first support member for placement longitudinally adjacent one of said bone segments in direct contact therewith;

means on said second support member for placement longitudinally adjacent another bone segment contiguous to said one bone segment and in direct contact therewith and substantially longitudinally aligned with said first support member;

means for releasably mounting said first and second support members to said bone segments;

a manually operable adjusting member;

means on said first and second support members for imparting longitudinal movement to one of said support members in response to operation of said adjusting member and for maintaining substantial longitudinal alignment of said first and second support members; and,

means for preventing rotational movement of said first and second support members during said longitudinal movement thereof.

2. An orthopedic apparatus as set forth in claim 1, wherein said placement means on said first and second support members comprises a concave contoured surface on each of said support members.

3. An orthopedic apparatus as set forth in claim 1, wherein said releasable-mounting means on said first and second support members comprises:

a plurality of pin members for placement within said bone segments; and,

a plurality of apertures in said first and second support members for receiving said pin members.

4. An orthopedic apparatus as set forth in claim 1, and comprising:

means mounting said adjusting member for rotational movement in response to operation thereof; and,

said movement-imparting means includes means for imparting longitudinal movement in respective opposed directions to said first and second support members in response to rotational movement of said adjusting member.

5. An orthopedic apparatus as set forth in claim 4, wherein:

each support member includes a first portion and a second portion;

said first portion having means for placement longitudinally adjacent a respective bone segment; and,

said rotation-preventing means comprises means on each second portion for slidably connecting the second portion of one support member to the second portion of the other support member.

6. An orthopedic apparatus as set forth in claim 5, wherein:

said adjusting member includes driving gear means; and,

said movement-imparting means comprises first and second gear means on the respective second portions of the first and second support members for simultaneous engagement with said driving gear means.

7. An orthopedic apparatus as set forth in claim 6, and further including movement-restricting means for permitting longitudinal movement of the support members in a first set of opposed directions while preventing longitudinal movement in a second set of opposed directions opposite of said first set.

8. An orthopedic apparatus as set forth in claim 7, and comprising:

means for mounting said movement-restricting means in a first position in which said movement-restricting means permits diverging longitudinal movement of the support members while preventing converging longitudinal movement thereof; and,

means for mounting said movement-restricting means in a second position in which said movement-restricting means prevents diverging longitudinal movement of the support members while permitting converging longitudinal movement thereof.

9. An orthopedic apparatus as set forth in claim 7, wherein said movement-restricting means includes:

a gear on one of said support members;

a pawl;

means for mounting said pawl in a first position on said one support member for a first biased engagement with said gear; and,

means for mounting said pawl in a second position on said one support member for a second biased engagement with said gear.

10. An orthopedic apparatus as set forth in claim 4, wherein said rotation-preventing means comprises:

a first bore extending longitudinally within said first support member;

a second bore extending longitudinally within said second support member and axially aligned with said first bore;

a rod having opposed end portions;

means for fixing one end portion of said rod to said first bore; and,

means for slidably mounting another end portion of said rod to said second bore.

11. An orthopedic apparatus as set forth in claim 10, wherein said adjusting member comprises a threaded second rod including first and second oppositely threaded sections.

12. An orthopedic apparatus as set forth in claim 11, wherein said rotational-movement mounting means comprises:

a third bore extending longitudinally within said first support member; and,

a fourth bore extending longitudinally within said second support member and axially aligned with said third bore.

13. An orthopedic apparatus as set forth in claim 12, wherein said movement-imparting means comprises:

means on said third bore for threadably engaging said first threaded section; and,

means on said fourth bore for threadably engaging said second threaded section.

14. An orthopedic apparatus as set forth in claim 10 wherein said movement-imparting means further includes means for imparting longitudinal movement to one of said support members in response to rotational movement of said adjusting member.

15. An orthopedic apparatus as set forth in claim 14, wherein:

said adjusting member comprises a threaded second rod including first and second opposed end portions;

said rotational-movement mounting means comprises:

a. a third bore extending longitudinally within said first support member; and,

b. a fourth bore extending longitudinally within said second support member and axially aligned with said third bore; and,

said movement-imparting means comprises:

a. means on said fourth bore for threadably engaging said first end portion of said threaded second rod;

b. a first gear;

c. means mounting said first gear to said first support member for rotational movement of the first gear; and,

means mounting said second end portion of the threaded second rod within said third bore for imparting longitudinal movement to said second support member in response to rotational movement of said first gear.