A DEVICE FOR BONE SUPPORT WITH IMPROVED ROTATIONAL STABILITY

• US 20160256202A1
• Filed: 10/21/2014
• Published: 09/08/2016
• Est. Priority Date: 10/22/2013
• Status: Active Grant

• Current Assignee: General Surgical Company (India) Pvt Ltd.
• Original Assignee: General Surgical Company (India) Pvt Ltd.
• Inventors: HALDER, Subhash Chandra
• Granted Patent: US 9,936,989 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: A61B 17/725 with locking pins or screws of special form
• CPC Class Codes: A61B 17/7266 with fingers moving radially outwardly
• CPC Class Codes: A61B 17/7283 with special cross-section of the nail
• CPC Class Codes: A61B 17/744 the longitudinal elements coupled to an intramedullary nail

Abstract

A bone support fixating device with a longitudinally slotted hip screw which permits operative compression of the fracture and holds this compression yet allows sliding as further compression of the fracture occurs under forces of weight bearing; comprising a hollow cylindrical shaft with a screw portion at its upper proximal end and four equally spaced longitudinal grooves at its lower distal end, having three equally distant angled holes between the ends, through which three wires can be inserted, the three ‘elastic’ proximally curved wires, welded, glued or crimped distally, can be inserted into the hip screw collectively called the ‘tri-wire’; The proximal end has the wires curved outward, with all three wires equally spaced; upon pushing the tri-wire into the hip screw, the wires goes through the angle holes in the hip screw and provides three projections equally spaced; which improves the rotational stability of the proximal fracture fragment.

Claims

1. A bone support fixating device comprising of an hollow intramedullary rod with a smooth anterior medial curve;

an extended hip screw;

a set screw;

an elongate device collectively called the ‘

tri-wire’

;

a locking screw 6;

the intramedullary rod comprising an upper cylindrical proximal portion and lower distal portion;

the upper end of the proximal portion having a threaded hole through which a threaded set screw passes in order to secure the hip screw towards the bottom of the proximal portion;

the length of which is approximately ⅓

of the total length of the rod;

an upwardly inclined hip screw receiving hole to fix the hip screw through the hole with a threaded part of the hip screw entering the hip bone;

the edges of the inclined hole at the proximal portion having a ‘

C shaped surface;

having a narrow bore formed through the lower part of the proximal portion of the rod and through the complete distal portion of the rod to minimise the use of materials to provide a fixating device which is light;

an end cap receiving threaded portion through which an end cap travels through;

the end cap receiving threaded portion having a larger diameter than the set screw receiving female thread;

having three openings at the proximal end for easy griping;

the distal end having a conical section with a smoothly rounded end;

having horizontal oblong slots with smoothly curved surfaces, formed through the distal cross section;

three equally spaced elongated V-grooves with smoothly formed curved surfaces, formed along the exterior face of the distal portion 8 of the rod resulting in a cloverleaf like cross section;

a hip screw comprising a hollow shaft having a self-tapping threaded portion at its proximal end and four equally spaced longitudinal grooves at its distal end;

the grooves having variable heights at different points to aid in dynamisation;

provided with a narrow longitudinal bore from one end of the screw to save on materials and weight;

having two co-axial bores;

provided with a substantially flat distal end face with a mild chamfering or rounding, in such a manner that any possibility of post-operative perforation of the cortex of the femoral head is minimised;

the distal end of the hip screw having four cruciate slots and wide threaded bore;

an end cap at the distal end over the ball of the tri-wire to prevent distal migration of the tri-wire;

the end cap comprising of a shaft with a hole to take the ball of the elongate device in such a manner that the elongate device is extractable;

the end cap further comprising of a hexagonal head and a threaded portion

with a step down at the end, easing the entry into the distal thread bore in the hip screw, the hip screw being located within the inclined fixing hole;

the set screw being located within the threaded bore in such a manner that the smoothly rounded lower end of the set screw is located within one of the four grooves of the proximal end of the hip screw;

ensuring that the fixating device is fitted to a patient with the hip screw located in the ideal position with respect to the fixing hole;

the set screw comprising of a solid shaft having a threaded upper end and smoothly rounded ball-nose lower end, there being a hexagonal hole formed through the top face of the shaft to receive an Allen key;

the locking screw comprising a threaded shaft portion, an enlarged head portion with a hexagonal hole formed through the top face to receive an Allen key and a self-tapping threaded end;

being long enough such that the head projects outside the shaft of the femur and the self tapping portion cuts a path into the opposing wall of the femur;

the elongate device is constructed by welding together three stainless steel wires of equal length with rounded or chamfered tips;

the said wires are pre-sprung, flared and strong;

comprising of a rod having three holes into which the stainless steel wires are inserted and welded, brazed, soldered, crimped or press-fit;

the said rod consisting of an enlarged head, a ball-ended tip with a flat milled for easy manipulation as the axis of the ball is directly on the longitudinal axis of the rod, thereby at the centre of the axis of the elongate device;

being positioned to move through the three tear drop slots in the hip screw;

in such a manner as to enable these projections to penetrate the bone surrounding the leading end of the bone support to prevent rotation;

the nail end cap comprising of a solid shaft, threaded portion, an enlarged head flat top surface and an Allen key receiving hexagonal hole, being secured to the intramedullary rod through the threaded hole;

the projections being guided out of the elongated tear drop holes on the hip screw;

the elongated tear drop holes being placed on a tapered neck at a forward angle on the tapered neck of the hip screw with a wedge shaped leading edge;

the tips of the wires moving along the rod in the direction of the hip screw;

the wedge shaped leading edge bringing about the guiding;

the back edge of the wedge also angled to enable minimal stress concentration at pivot point of the wires with respect to the back edge;

the length of each slot proportioned in such a manner as to provide a greater constraint to each of the wires as they emerge from the rod to engage the bone;

providing maximum control over movement between wire and the hip-screw, resulting

in faster bone healing;

the tri-wire not only stablises the intertrochanteric fractures but also maintains the rotational stability of the intracapsular fractures of the neck of femur, widening the indication to the intracapsular fractures by closed intrameduallry method.

2. The openings as claimed in claim 1, located at the distal end of the intramedullary rod being circular, formed through the distal cross section, wherein the edges are formed with smoothly curved surfaces.

3. The openings as claimed in claim 1, located at the distal end of the intramedullary rod, being a combination of circular and oblong, formed through the distal cross section, wherein the edges are formed with smoothly curved surfaces.

4. The axis of the upper proximal portion over rod as claimed in claim 1 is at an angle of 4°

.

5. The tapered neck of the hip screw as claimed in claim 1 substituted with a straight neck.

6. The elongate slot as claimed in claim 1 located in the walls of the hip screw rod having a length ‘

L’

facing radially with simple square ends;

the slot length L being of length sufficient to provide a guiding means, allowing the end of the associated projection to be pushed through the slot and into the surrounding bone;

the fit between the projection and slot be snug as possible with minimum clearance.

7. The tri-wire as claimed in claim 1 having a forward angle leading edge and a straight square back edge.

8. The slots as claimed in claim 1, formed by machining and are shorter;

the leading edge of each slot is swaged inward radially, thereby providing more effecting guiding means;

resulting in the leading edge of each wire finding the guiding means through the slot and the slot dimensions being closer to the wire diameter.

9. The wall of the hip screw as claimed in claim 1, being cut in such a manner that no significant material is removed by this incision to the wall of the rod;

the leading side of the incision is the swaged inwards leading a longitudinally facing window in through which the wire emerges;

the guiding means being provided by the shaped leading end of the wire and the inwardly deformed edge of the exit window.

10. The hip screw as claimed in claim 1, being provided with an annular member fitted within the hip screw;

the said annular member has shaped surface arranged to cooperate with the wires;

the said annular member projects inwardly of the hip screw such that the leading edges of the wires engage the annular member before reaching the opening in the wall of the hip screw;

a tunnel is created which gives further support to the emerging wire, minimising movement relative to the hip screw in all directions;

a precise plug fitted into the end of the hip screw accomplishes this.

11. The plug as claimed in claim 15, substituted with an annular member comprising a sleeve welded inside the rod.

12. The plug as claimed in claim 15, substituted with separate inserts, fitting the machine slots being separately welded, brazed, soldered or snug fit into place.

13. The tear drop shaped hole as claimed in claim 1, substituted with a straight hole.

14. The tear drop shaped hole as claimed in claim 1, substituted with a slot.

15. The tri wire as claimed in claim 1, offering superior manipulation in direct proportion to the large flat surface area.

16. The elongate device as claimed in claim 1 comprising of two flat pre-sprung flats projecting through the hip screw;

the separate flat pre-sprung flats not being welded to each other but welded only at the hip screw, which consist of a single hole or slot.

17. The elongate device as claimed in claim 1, comprising of a plurality of square cross-section wires with corresponding number of slots or holes.

18. The elongate device as claimed in claim 1 comprising of plurality of round cross section wires with corresponding number of slots or holes.

19. A bone support fixating device as substantially described herein with reference to the accompanying drawings.