FIELD OF THE INVENTION

The present invention relates generally to bone distraction, and more specifically to system and methods for performing distraction in bone in cost effective, secure, and versatile manner.

BACKGROUND OF THE INVENTION

Distraction is a technique by which two segments of a bone after cutting are gradually separated from each other to allow new bone to be formed between the two segments. As the techniques of distraction have evolved, the devices of distraction are also being modified and developed to suit the ever challenging demands of difficult bone anatomy. Many distractors have been developed for clinical distraction having varying assembly and mechanisms of action but all have the common design of fixation to the bone using two pin holes, often in the same axis.

This provision for only two pins on the pin holding clamp in one axis often makes them difficult to apply in situations where the bone stock is limited and asymmetrically distributed on either side of the osteotomy. It is clear that there is need of a better design of distractor which allows it to be fixed securely to the underlying bone to facilitate satisfactory distraction.

SUMMARY OF THE INVENTION

The invention creates a bone distractor which has multiple slots for holding the pins on the clamp arranged in a triangular geogetry. This particular arrangement allows a better grip on the bone segments than the conventional unidirectional distractors which have slots for only The addition of multiple pin slots on the clamp affords many unique advantages to this invention. In many clinical situations the bones on either side of the osteotomy are frequently of different topography and physical shape which sometimes makes the application of the conventional distractor difficult in these circumstances. Moreover the pin slots of the conventional distractor are in the same axis so in these situations there may not be enough bone stock available in this particular axis to allow stable fixation of the conventional distractor. This invention with multiple pins arranged in a triangular manner at an angle of 60° allows the placement of the pins according to the best bone geometry available in that particular situation thus allowing this distractor to be securely applied even on asymmetrical and uneven bony contour on either side of the osteotomy. At any given time the alternative axes provided by this arrangement allows placement of atleast two pins using any two of the available multiple holes for fixation of the distractor. If three pins slots on the clamp are used then it conjures up a very stable fixation of this distractor. All the multiple pin slots are individually controlled by internal headless screws which can be used to tighten the Schanzscrew / K wire which helps in attaching the distractor to the bone. Additionally the two pin holding clamps of the distractor can swivel to full 360 degrees of motion along the distraction rod which allows maximum versatility in terms of 'lie' of this invention while applying this distractor on to the bone.

A millimeter scale is given on the distraction rod which helps in ready measurement of the amount of distraction done as calculated by increasing distance between the moveable and fixed pin holding clamps. The threads on the distraction rod allow unobstructed and free movement of the nut-moveable clamp assembly over the rod.

A patient activation screwdriver with arrow marking allows comfortable and controlled activation-distraction of the moveable pin holding clamp on the threaded rod. The screwdriver is constructed to allow good grip in the palm of the hand so that smooth movement is maintained. One complete turn of the screwdriver advances the moveable clamp by one mm. The device activation screwdriver allows tightening of the various internal headless screws which in turn hold the pins onto the clamps. The same screwdriver is also used to tighten the fixed and mobile clamps on the distraction rod. Once the distraction is complete, the mobile clamp can also be tightened and fixed in a particular position for the purpose of consolidation of the regenerate.

The distractor of this invention hence is more versatile, stable and patient friendly than the conventional two pin hole distractors. The patient, after discharge from the hospital is educated and instructed to turn the screwdriver periodically, once in the morning and night in the appropriate direction. By application of this slow gradual force the bone elongates and this expansionary force also helps in expanding the soft tissue envelope.

This distractor permits elongation of bones of the craniofacial skeleton without the use of bone grafts or procedures of osteosynthesis or intermaxillary fixation. It reduces the overall morbidity, operative time and also days of hospitalization for the patient. The mandible which can be deficient due to various reasons like congenital deformity, post-traumatic or post-surgical resection can be easily and reliably elongated and reconstructed without using autografts or synthetic substitutes. This distractor can also be used for distraction of the monobloc for fronto-orbital advancement. The unique design and stability of this distractor come in optimum use for this particular indication.

This distractor has application for bone regeneration and elongation in the limbs for treating bone shortening. Thus metacarpal, metatarsal or the phalanges of upper or the lower limb when deficient due to traumatic loss, post-surgical resection or congenital disease can be easily lengthened by this invention. The multiple pin design comes in handy in these situations as the bone stock is frequently deficient on either side of the osteotomy in the limb skeleton.

This invention together with its various indications thereof, will be more fully explained by the attached drawings and the following descriptions. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Figure 1 is the side view of a system for bone distraction, according to an exemplary embodiment of the present invention;

Figure 1A is an alternative embodiment of the clamp design of the system for bone distraction, according to an exemplary embodiment of the present invention;

Fig. IB is an alternative embodiment of the design of the system for bone distraction showing multiple holes in the clamps for passing the Schanz screws / K wires, according to an exemplary embodiment of the present invention;

Figure 2 is the top view of the system for bone distraction, according to an exemplary embodiment of the present invention;

Figure 2A is enlarged view of a part of the top of distraction rodof the system for bone distraction, according to an exemplary embodiment of the present invention;

Figure 2B is the endon view of the fixed screw holding clampcapable of full 360 ⁰ rotation on the distraction rod and controlled by a headless screwof the system for bone distraction, according to an exemplary embodiment of the present invention;

Figure 2C is the endon view of the moveable screw holding clampcapable of full 360 ⁰ rotation on the distraction rod and controlled by a headless screw of the system for bone distraction, according to an exemplary embodiment of the present invention;

Figure 2D is the view of the nutof the system for bone distraction, according to an exemplary embodiment of the present invention;

Figure 2E is the view of the patient activation screwdriverof the system for bone distraction, according to an exemplary embodiment of the present invention; Figure 2F is the view of the device activation screwdriverof the system for bone distraction, according to an exemplary embodiment of the present invention;

Figure 3 is a view of the invention being used to elongate the mandible, according to an exemplary embodiment of the present invention;

Figure 4 is a view of the invention being used to elongate a portion of the cranium, according to an exemplary embodiment of the present invention; and

Figure 5 is a view of the invention being used to elongate the proximal phalanx of hand, according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Fig. 1 which is a side view of a system for bone distraction, according to an exemplary embodiment of the present invention. The distractor uses two clamps 1A and IB which are connected to each other by a threaded distraction rod 2. Clamp 1A is fixed at one end of the distraction rod at its end 3. Clamp IB is moveable along the distraction rod. Both these clamps are capable of 360 degree swivel movement around the distraction rod. This swivel movement is controlled by a headless screw in each of these clamps. Both these clamps in the lower half have atleast3 holes each 6-11 which are used for anchoring pins or screws to the clamp. These holes are designed in a triangular orientation with each other. Each hole is traversed by a headless screw which helps in tightening the pins/ screws to the clamp. The upper part of the clamp has a smooth unthreaded hole through which the distraction rod passes. ClampslAand IB can be tightened to the rod 2 by a headless screw 5 while the clamp IB is moveable along the length of the rod 2 by the help of a nut 4. This nut engages to the threaded rod on one side while its other part slides into the side of the clamp IB. The holes are so arranged that hole 7,9 are nearer to the distraction rod and holes 6,8,10,11 are farther from the distraction rod. This design embodies a square shaped central midline cut in the lower half of the clamp with holes arranged on three sides of the cut. Referring to Fig. 1A which is an alternative embodiment of the design of the clamps 1A and IBas 1C, according to an exemplary embodiment of the present invention. In this design, instead of a central midline square cut, there is a central square shaped projection in the midline at the lower end of the clamp which is away from the clamp end harbouring the distraction rod. The same design of three holes is made in this clamp with two holes 9A and 10A at the lower part and a single midline holel lA in the square projection. This alternative design also carries the same versatility and functionality as the clamp design. All these holes are also controlled independently by headless screws.

Referring to Fig. IB which is an alternative embodiment of the design of the invention showing multiple holes in the clamps for passing the Schanz screws / K wires.

Referring to Fig. 2 which is a top view of the system for bone distraction, according to an exemplary embodiment of the present invention. Clamp 1A is fixed to the distraction rod 2 at end 3. This fixation is controlled by headless screw 5. Clamp IB slides on the distraction rod. Each of these clamps can swivel to 360 degree around the distraction rod and can be tightened into a particular position using the headless screw 5. The scale on the distraction rod 2 helps in measurement of the distraction distance. Nut 4 engages on the threads of the distraction rod and its flange slides into a slot in clamp IB. This nut 4 is activated by a patient activation screwdriver which can be activated by either the surgeon, patient or the third party.

Referring to Fig. 2A which is an enlarged view of a part of the top of a distraction rod 2, according to an exemplary embodiment of the present invention. This threaded rod has markings in form of complete lines 2A and incomplete lines 2B at regular distance. The distance between 2A and 2B equals 2 mm and hence distance between 2A's is 4 mm.

Referring to Fig. 2B which is an endon view of the Clamp 1A when looking from the side of the free end of the distraction rod 2, according to an exemplary embodiment of the present invention. The upper part has a smooth hole 12 through which the distraction rod passes. Referring to Fig. 2C which is an endon view of the Clamp IB when looking from the side of the free end of the distraction rod, according to an exemplary embodiment of the present invention. The upper part has a smooth hole 12 through which the distraction rod passes. In addition to this, this clamp has an additional socket 13 which is cut out so that it accepts the flange 15 (Fig. 2C) of the nut 4.

Referring to Fig. 2D which is a view of the nut of the system for bone distraction, according to an exemplary embodiment of the present invention. The wider part 14 with threads on the inner aspect engages with the distraction rod while the flange 15 slides onto a matching slot 13 (Fig. 2C) onto the Clamp IB.

Referring to Fig. 2E which is a view of the patient activation screwdriver of the system for bone distraction, according to an exemplary embodiment of the present invention. It has a hollow shaft 16 which accommodates and slides over the distraction rod 2 and the end of this shaft 17 engages with the nut 4. This end has a marking line 17A which denotes the amount of rotation of the screwdriver. The arrow 17B denotes the direction of movement of the screwdriver to the patient or caregiver which leads to separation between the clamps and thus causing distraction. One full turn of 360° as confirmed by the mark 17A moves the clamp to a distance of 0.5 mm. This is also indicated on the body of the screwdriver 19A for the ready reference of the patient. The end on view of the hollow shaft 18 is shown in the inset which shows the hexagonal configuration of the internal surface. The surface of the handle of this screwdriver is made flat 19 so as to allow a comfortable grip between the fingers and thumb.

Referring to Fig. 2F which is a view of the device activation screwdriver of the system for bone distraction, according to an exemplary embodiment of the present invention. It has a solid shaft 20 which engages in the internal screws of the clamps to help in tightening and assembly of the device. The endon view of this shaft 21 is shown in the inset.

Referring to Fig. 3 which is a view of the invention being used to elongate the mandible, according to an exemplary embodiment of the present invention. In these illustrations, the created on the mandible in the area desired to be elongated. The completeness of the osteotomy is confirmed before proceeding with fixation of the distractor. The distractor is then fixed onto the mandible with the help of Schanz screws. First the line of osteotomy is marked as per the operative plan and screw locations (3) on both the sides of osteotomy are predetermined and marked. The screws (3 on each side) are drilled bicortically into the bone on both the sides of the marked osteotomy site keeping adequate distance from the line of osteotomy. After drilling of each screw the fit of the distractor is checked. Once all the screws are drilled, the osteotomy is completed and the distractor is fixed with these screws on clamps 1A and IB with the help of internal headless screws. Rotation- activation of the distraction rod 2 causes the clamps to move apart as indicated by the arrow 23 and expand thus causing distraction of the mandible. This stimulates new growth at the site of the osteotomy and thus regenerates the mandible.

Referring to Fig. 4 which is a view of the invention being used to elongate a portion of the cranium, according to an exemplary embodiment of the present invention. In the fronto- orbital advance, an osteotomy 24 is performed on the medial-lateral walls and on the base of orbit after placing three monocorticalSchanz screws at predetermined sites on either side of the line of osteotomy. The osteotomy 24 continues to the frontal bone more or less parallel and infront of the coronal suture. Once the osteotomy is completed the distractor is applied by securing it to the screws by the clamps 1A and IB at the level of the temporal fossa. The same procedure is done on the other side of the head. The distractor hence is placed externally so that activation is easier and device malfunction is avoided which is not an infrequent occurrence in submerged devices.

Referring to Fig. 5 which is a view of the invention being used to elongate the proximal phalanx of the hand, according to an exemplary embodiment of the present invention. Osteotomy 25 has been done and clamps 1A and IB have been applied on either side of the osteotomy. Schanz screws have been used to fix the bone ends with these clamps. The same invention can also be used to elongate the metacarpal, metatarsal or any other phalanx of the upper or lower limb following shortening of loss of the bone. In general for all of the listed uses, the distractor is activated so it permits elongation at a rate of 1 mm a day. This elongation is continued till the desired end point after which a period of consolidation is allowed.

The invention is made of stainless steel; but those of ordinary skill in the art readily recognize that this distractor can be manufactured from hardened silicone, hardened plastic, titanium or any number of other materials.

It is clear that the present invention creates a stable yet effective distractor which permits the regeneration of bone even in situations where the bone anatomy is difficult for stable fixation of conventional distractors. The addition of multiple pin slots on the clamps is the reason for enhanced stability and versatility of this invention.

CLAIM

What is claimed is:

1. A system for bone distraction, comprising:

atleast a pin holding clamp with a plurality of holes configured to allow secure fixation of a distraction device in situations where the underlying bone stock is uneven, asymmetrical and of different contour on either side of the osteotomy,

wherein the pin holding clamp is in the shape of a rectangle which has a square cut out at one end, wherein the square cutout is directly opposite to a third pin hole which is also a middle pin hole on atleast a side of the square cut out, wherein the square cut out is adapted for providing a space for housing a headless screw for control of the middle pin hole, wherein a plurality of pin holes on the sides are also independently activated by headless screws which are housed on either side of the square cut out at the same end of the clamp;

wherein the holes on the pin holding clamp are adapted in the shape of a triangle so that flexibility and versatility in placement of bone fixation screws in these holes is maintained to accommodate all possible geometry and configuration of the bones being treated with this invention,

wherein each holes is independently controlled by a headless screw which helps in tightening a bone holding screw in the holes, wherein atleast a headless screw is activated by a clockwise screw action of a device activation screwdriver,

wherein alternative design of the pin holdingclamp having atleast one of a square cut in the clamp, a square shaped projection in the midline or any combination thereof, wherein the square shaped projection is adapted to houses atleast a hole and the other two holes are located in a lower part of the pin holding clamp,

wherein any alternative design of the pin holding clamp having more than 2 holes placed in such a manner which would allow secure placementof this device on the bone, wherein the pin holding clamps have been so designed that they can be swiveled / rotated along the axis of the distraction rod so that the clamps may be fixed at any desired position with respect to the distractor and the underlying bone.