GB2076657A

GB2076657A - Apparatus for external fixation of part of the human or animal skeletal structure

Info

Publication number: GB2076657A
Application number: GB8116744A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-05-31
Filing date: 1981-06-01
Publication date: 1981-12-09

Abstract

Apparatus for the external fixation of part of the human or animal skeletal structure particularly for a long bone such as a tibia without the use of plaster or of penetration into the interior of the bone and usable for applying traction to a bone, such as a tibia, and for arthrodesis of the ankle or knee joint comprises a pair of collars 1 through which the limb of a patient is passed and spacing rods 2 interconnecting the collars. The rods 2 carry swivellable and axially- adjustable clamps 3 which are fitted with pins 4 which penetrate the limb and engage the outer surface of a bone to be set. The pins 4 are slidable with respect to the clamps and together hold the bone or fractured parts firmly in the required position for setting. By appropriately inclining the pins 4 and sliding the clamps 3 on the rods 2 traction may be applied to the bone. <IMAGE>

Description

SPECIFICATION Apparatus for external fixation of part of the human or animal skeletal structure The invention relates to apparatus for the external fixation of part of the human or animal skeletal structure and is particularly, but not exclusively, for the external fixation of a tibia.

Hitherto it has been the practice to fix a fracture of a tibia or other long bone of a limb either by encasing the limb in plaster and/or by penetration of the fractured bone by pins passed transversely through the bone. The penetration of the bone is undesirable as it could lead to infection or damage to the structure of the bone or both. An object of the invention is to provide apparatus whereby the bone can be held rigid during the joining and healing of the fracture without the need to penetrate the bone or the encasing of the limb in plaster.

According to the invention, the apparatus comprises at least a pair of collars through which a limb is passed, the collars being spaced apart longitudinally of the limb by a plurality of elongate spacers extending between the collars longitudinally of the limb, and spaced apart circumferentially of the collars, each of the spacers carrying a plurality of clamps slidable, when loosened, to selected positions in the length of the respective spacer and each clamp carrying a pin extending inwardly towards the longitudinal axis of the collars, the pins being adjustable in the respective clamps to adjust the effective lengths of the pins inwardly of the clamps, to enable the pins to be inserted into the limb to engage against the outside of a bone or bones to be fixed and hence to grip the or each bone firmly between a plurality of pins.

Where a fractured bone is to be supported the pins would support the bone at each side of the fracture and, where necessary, some of the pins would be used to support portions of bone at the site of the fracture.

Preferably there are three spacers spaced apart at substantially equal circumferential distances around the collars, whereby at each transverse plane at which the bone is gripped, the bone will be supported at three points spaced apart circumferentially around the bone.

The pins are preferably pointed at the ends which, in use, are inserted into the limb and engage the bone, whereby the pointed ends of the pins can be located in locating holes made in the outer surface of the bone.

The spacers are conveniently cylindrical rods and the clamps can be swung around the rods, as well as being slidable along them, thereby to enable the angles of inclination of the pins in planes parallel to the collars to be altered.

The clamps may also have swivel joints to enable the pins to be set at inclinations toward one or other of the collars, whereby the pins can be used to impart a component of thrust longitudinally of the bone. In this way traction or extension of a bone can be effected without using conventional traction methods requiring pins to be passed transversely through the bone and then pulled by weights in the longitudinal direction of the bone. The clamps carrying pins used in accordance with this invention, to effect traction or extension of a bone may be provided with calibrated adjusting devices to effect adjustment of the clamps longitudinally of the spacers to produce a required extension or rate of extension.

By way of example, apparatus for the external fixation of a skeletal fracture of a long bone of a limb is now described with reference to the accompanying perspective sketch of the apparatus, showing how the apparatus is used to grip a long bone, such as a tibia.

The apparatus comprises a pair of collars 1 which are held apart in a rigid structure by three spacer rods 2, each parallel to the longitudinal axis of the collars and spaced apart at substantially equal circumferential spacings around the collars.

Although two collars and three rods are shown, more than two collars and more than three rods may be employed. Each rod 2 has a plurality of clamps 3 thereon. Five clamps are shown on each rod but any desired number can be employed provided there are sufficient clamps to support pins to grip the bone, as hereinafter described. The clamps 3 are slidable, when loosened, along the respective rods 2 and also they can be swung around the rods. The clamps are secured in positions to which they have been set by clamping screws or bolts. Each clamp 3 carries a pin 4 at a position offset transversely from the axis of the respective rod 2 which extends inwardly towards a central region of the apparatus. The pins 4 are adjustable in the clamps 3 to enable the effective lengths of the pins inwardly of the clamps to be altered.The effective lengths of the pins 4 may be adjusted by means of screw-threaded outer portions of the pins engaging screw-threaded holes in the clamps and are secured by lock-nuts or they may be slidable and secured by clamping screws. The inner ends of the pins 4 are pointed to engage in holes made in the outer surface of the bone, as hereinafter described. As the pins will, in use, penetrate the limb to engage against the outer surface of the bone to be fixed, they are made of stainless steel or alloy permissible for such use.

The apparatus is used to fix a fractured long bone such as a tibia, by inserting the limb of the patient through the collars 1 so that the fractured bone is in a substantially central position like that shown for the bone 5 in the Figure. A X-ray photograph of the bone will have been made and the surgeon will position the limb with the fracture in the region of the intermediate transverse sets of pins 4. The pins 4 of at least the two end sets of pins, that is the sets adjacent the collars 1 will be adjusted in angular position, effective length and position axially of the respective rods 2 so that they can be inserted into the limb to grip against the bone in respective transverse planes one at each side of the fracture and at three positions spaced apart circumferentially around the bone, or a greater number of positions where there are more than three rods 2.The inner sets of pins are similarly adjusted and are inserted into the limb to engage the bone. These pins 4 may be used to support broken pieces of bone at the site of the fracture in the case of a compound fracture. In order to provide for firm location of the bone small surface holes may be made in the outer surface of the bone in which the inner pointed ends of the pins 4 can be located.

The apparatus is left in position on the limb with the pins 4 in the positions to which they have been set until the fracture has healed, which may be as long as several weeks. The apparatus therefore, in effect, forms a splint. When the fracture has healed, the pins are withdrawn from the limb and the apparatus is removed. The apparatus therefore effects fixation of the bone in an external or non-invasive manner, that is there is no penetration of the bone structure, except for the surface pin location holes, where these are formed. The apparatus therefore decreases the risk of infection and damage to the structure of the bone and also avoids the use of plaster. The described method of setting a fracture by using the apparatus provided by this invention, is particularly applicable to the treatment of fractures in a long bone of a child.

Although the apparatus is primarily intended for fixing a fractured long bone, such as a tibia, it could be used for arthrodesis of the ankle or knee joint by placing the apparatus in the manner of a cage around the lower part of the leg and ankle or around the knee and securing the appropriate bones with the pins 4 in a similar manner to that described hereinbefore. An end attachment forming an extension at one end of the apparatus may be required to secure the foot when the ankle is to be immobilised.

In a modified form of the apparatus which is not illustrated, some or all of the clamps 3 may be provided with swivel joints to enable the pins to be set in positions inclined towards one or other of the collars 1 instead of being set perpendicularly to the axes of the rods 2, that is in planes parallel to the collars 1, as in the illustrated example. By inclining pins 4 towards one or other of the collars 1 a component of thrust in directions longitudinally of the bone can be imparted to the bone. For example by inclining the pins 4 of the set adjacent one collar 1 towards that collar and by inclining the pins 4 of the set adjacent the other collar 1 towards that collar a bone can be placed in tension without need for the conventional traction apparatus requiring pins to be passed transversely through the bone. Similarly a bone can be extended in this way. For example a bone to be extended in a child could be cut through and extension applied between the two portions of the cut bone by using the apparatus in this way. The clamps could be provided with calibrated adjustment devices so that the two portions of the cut bone could be separated by a controlled distance each day by moving apart the sets of inclined pins 4 until the bone is of the correct length and can be allowed to heal and rejoin.

The apparatus formed by the assembled structure comprising the collars 1, rods 2, clamps 3 and pins 4 may be placed in a container or tray, when not in use, to enable it to be sterilised in an autoclave and kept in a sterilised container or wrapping until it is ready to be used.

Claims

1. Apparatus for the external fixation of part of the human or animal skeletal structure comprising at least a pair of collars through which a limb is passed, the collars being spaced apart longitudinally of the limb by a plurality of elongate spacers extending between the collars longitudinally of the limb, and spaced apart circumferentially of the collars, each of the spacers carrying a plurality of clamps slidable, when loosened, to selected positions in the length of the respective spacer and each clamp carrying a pin extending inwardly towards the longitudinal axis of the collars, the pins being adjustable in the respective clamps to adjust the effective lengths of the pins inwardly of the clamps, to enable the pins to be inserted into the limb to engage against the outside of a bone or bones to be fixed and hence to grip the or each bone firmly between a plurality of pins.

2. Apparatus as claimed in Claim 1 comprising three spacers spaced apart at substantially equal circumferential distances around the collars, whereby at each transverse plane at which the bone is gripped, the bone will be supported at three points spaced apart circumferentially around the bone.

3. Apparatus as claimed in Claim 1 or 2 in which the pins are pointed at the ends which, in use, are inserted into the limb and engage the bone, whereby the pointed ends of the pins can be located in locating holes made in the outer surface of the bone.

4. Apparatus as claimed in any preceding claim in which the spacers are cylindrical rods and the clamps can be swung around the rods, as well as being slidable along them, thereby to enable the angles of inclination of the pins in planes parallel to the collars to be altered.

5. Apparatus as claimed in any preceding claim in which the clamps have swivel joints to enable the pins to be set at inclinations toward one or other of the collars, whereby the pins can be used to impart a component of thrust longitudinally of~ the bone.

6. Apparatus as claimed in Claim 5 in which the clamps are provided with calibrated adjusting devices to effect adjustment of the clamps longitudinally of the spacers to produce a required extension or rate of extension.

7. Apparatus for the external fixation of part of the human or animal skeletal structure constructed and arranged substantially as described herein and shown in the accompanying drawing.