WO2007036954A1

WO2007036954A1 - Forearm interlocking apparatus

Info

Publication number: WO2007036954A1
Application number: PCT/IN2006/000372
Authority: WO
Inventors: Himanshu Bansal
Original assignee: Himanshu Bansal
Priority date: 2005-09-29
Filing date: 2006-09-19
Publication date: 2007-04-05

Abstract

An interlocking nailing system of -forearm bones with closed reduction is disclosed. The nail (1) has broad proximal end of 4.5 to 6.5 mm to engage proximal screw of 2.5 mm diameter. It has distal hole (5) of 0.5 mm to 2 mm where locking clip of 0.5 to 2 mm is introduced. The clip locks the nail to bone preventing rotation since construct of clip can be made as low as 0.5 mm diameter, nails up to 2 mm in diameter can be used successfully. The clip has a U-shaped arm (10) which is attached to the short arm of a L- shaped arm (11).

Description

FOREARMINTERLOCKING APPARATUS

This invention relates to a forearm interlocking apparatus which is an improvement in the techniques of closed reduction and internal fixation of fracture of forearm bones (radius and ulna) and in all other indications of fixation like deformity correction, tumour resection etc.

With this technique closed technique closed reduction (no incision around fracture) with adequate fixation can be performed, otherwise open reduction (means opening of fractures site by incision) and internal fixation with a dynamic compression plate is a gold standard and is still the treatment of choice in forearm fractures for last few decades.

The problems with this procedure are big skin incision and subsequent scar, increased operative time, as plate takes some space so problems in skin closure especially with both bones fractures, increased chances of infection, bone lyses beneath plate, increased risk of fracture after plate removal, more expensive implant plus increased cost of antibiotics.

Whereas in closed reduction only stitch incision at the entry point of nail and one stitch incision at both proximal and distal locking sites.

Surgeons in various places are now fixing forearm fractures with good results by closed reduction and internal fixation with square nail or other shape of nails. The only disadvantage is that this nail can not control rotation of fractured fragments which increases non union rates significantly. To avoid rotation a Plaster of Paris cast to be applied till union occurs and this causes stiffness, disuse osteoporosis etc. Moreover in fractures of proximal third in ulna (Montaggia fracture dislocation) and distal third in radius (Galezzi fracture dislocation) these nails cant even maintain length and thus lead to overriding, angulations and radioulnar joint subluxation.

The concept of interlocking has revolutionized the treatment of long bone fractures Tibia and Femur fractures in lower limb and humerus fractures in upper limb. With the advent of interlocking in these bones the earlier treatment modalities like open reduction and internal fixation with dynamic compression plate and screws and closed reduction with nails have become obsolete.

In long bones the diameter of medullary cavity is big and can allow the nails from 8mm to 1 1mm to negotiates easily so the screw holes for locking and screws of 4.5 mm diameter does not decrease the strength of construct. But till now no appropriate interlocking system for forearm fractures could be evolved because of small medullary cavity diameter of and no construct was stable in diameters of less than 3.5mm i.e. a screw of less than 2 mm will not be strong in forearm and to have a hole of 2mm in the nail the minimum diameter of nail to withstand hole of 2 mm should be at least 3.

These thick nails can not be introduced in the bones with small medullary cavity (in Indian and most of world population the majority of patients allow passage of 2.5 to 3mm nail by closed reduction.

These problems are overcome by the present invention which provides interlocking system in the nail with small diameters up to 2 mm. insertion is entirely by closed surgical technique, minimizing blood loss and infection potential cut out. Accordingly, A forearm interlocking apparatus comprising of a nail component and clip component in which the nails has threaded entry tip, broadened to with proximal hole and a distal hole to receive specially designed clip lock which has a straight arm of L portion to engage in bone and nail and another arm broadly shaped as U to snugly fit the bone curvature.

• closed stable reduction can be achieved without opening fracture in almost all patients with small medullary cavity

• secures rotation of fractured fragments

• avoids big skin incision and subsequent scar (in closed reduction only stitch incision at the entry point of nail and one stitch incision at both proximal and distal locking sites • decreases operative time

• eliminates the problem of skin closure as sometimes encountered with plate which takes some spaces especially with both bones fractures,

• decreased chances of infection

• problem of bone lyses beneath plate is avoided • No risk of fracture after nail removal

• Less expensive implant plus cost of antibiotics reduced drastically

• No need of pop immobilization postoperatively. Proximal one third fractures even in olecranon fractures, middle and distal third fractures of radius and ulna.

Severely comminuted fractures

Spiral and segmental fractures Osteoporotic bones

Comminuted fractures with small medullary canals

Treatment of non-union, mal union and bone lengthening and shortening

Open fractures

Congenital deformed bones After osteotomy correction of curved bones e.g. Sikkabab osteotomy

Pathological fractures

SHAPE-square in crossection for better torsional stability

Can have other shapes as well. Some other optional shapes are-smooth round, triangular, diamond etc. MATERIAL-stainless steel (or any other bioinert material e.g. titanium)

SIZES - from 2mm to 4.5mm diameter, the length from 20 cm to 30 cm. Length can be increased or decreased in specific cases,

This interlocking nail comprises of -

Broadened top is smooth round in shape (can be square or of any other shape) of 4.5- 6.5 mm in diameter and 5 yo 7 cm in length.

Proximal locking hole of 2.5mm to 3.5mm

Proximal hole can be 2cm, 3cm and 4 cm beneath entry tip in different set of ulnar nails so as to place the proximal screw beneath coronoid.

In children with open growth plates the location of proximal hole is 1 cm below the entry tip because we make entry point distal to the growth plate

In radial nails 1.5 to 2 cm distance from entry tip is sufficient.

Proximal hole is straight but it is made oblique antegrade of 145 degree hole in some ulnar nails which are to be used in cases associated with fracture olecranon also.

Entry tip is threaded from inside to engage the introducing Jig. Positive lock provides secure instrument fit for accurate proximal and distal targeting.

Entry tip can be threaded in outer diameter also. Entry tip can be capped also.

Distal locking hole of Range 0.5mm to 2mm depending on thickness on nail (0.5mm in 2-2.5mm nail, 1 mm in 3 -mm nail) lcm to 3.0 cm above the distal pointed tip in ulnar nails.

5-7 cm beneath the distal pointed tip in ulnar nails.

5-7 cm beneath the distal tip in radial nails.

The distal hole can be made more distal or proximal in some nails to complete the inventory for some atypical fractures geometry

Cold work expansion of distal hole for increased strength

Position of holes can be anterior-posterior or mediolateral-

Anterior to posterior transfixation distal hole in ulna otherwise usually medial to lateral transfixation hole in proximal ulna and for both the holes of radius One can have two proximal and two distal screws as well.

In ulnar nail the tip is pointed and in radial nail it is bevelled (like R)

Tip can also be blunt or r shaped or fluked end, fluted.

Clip Lock

The main feature is specially designed clip to engage distal hole and then lock the nail to bone with additional clip locking to bone. Bicortical fixation along with clip fit on curvature reduces the possibility of back out and can be used to help maintain length and prevent rotation.

This clip is made up of stainless steel from 0.5 mm to 2 mm in diameter.

This clip design makes it possible to lock the distal end at such low width. (Screws of upto 1.5 mm diameter will not be strong enough) interlocked forearm nailing is difficult in low medullary cavity diameters.

The clip has long arm with blunt/pointed tip to fit into the hole. It is a combination of

L and U arms. U arm gets joint with short arm of L (approx 4-6 mm) at one end.

Long arm (size depends on the length measured after drilling) goes inside the bone, traverses the hole of nail and locks the nail to bone. It can be threaded. Then rotate the U arm of clip so that U gets snugly fit into the curvature of bone

The size of U arm is made in few mm increments so as to pick the best snugly fitting clip. Their can be alteration of U shape of the clip.

INSTRUMENTATION It precise and easily reproducible

Instruments are basically for introducing the nail and extracting the nail if required

It consists of a hammer, nail drill guide bolt or supine driver and a forearm nail driver/extractor tube. Hammer is cannulated to slide over forearm nail driver.

Nail drill guide bolt has an expanded base which has a hole of 1.5 mm which is threaded to engage forearm nail driver. The bolt tapers gradually and then it is joint by a 3 cram long rod the outer core is threaded at its tip to engage the entry tip of the nail.

Forearm nail driver is a long rod with threads at outer core of one end to engage in the bolt and the other end is broad and thick so as to face the force of hammer during extraction. We have also developed an instrument called as Jig which enables us to put proximal and distal screws in their respective holes with precision.

The jig is different for right and left side. Proximal insertion of screws is 100% accurate. Distal insertion is 90-98% accurate. Carm is required at times but the jig makes it easy to locate the distal hole. One may locate the holes with free hand technique under Carm image intensifier also.

Design of jig is also unique.

Distal jig comprises of one long L shaped arm (guide bar) for locating distal hole and one small L shaped arm for proximal hole. Both these arms are at 90 degree to each other. Long portion of long L is 35 cm long it has holes at every cm and the small portion is

5 cm.

Small L has big arm of 10 cm which has three holes for proximal locking. The short arm is 4-5 cm in length which is joint to the short arm of big L arm. At this junction there is a cannulated tube into which nail drill guide bolt enters. Distal jig can be made up of steel, iron, aluminium, titanium or any radiolucent material.

Drawing Description- Fig. 1 shows forearm interlocking nail according to invention

Fig. 2 shows instrumentation for insertion and extraction Fig. 3 shows the jig for both proximal and distal holes

Fig. 4-11 describes the technique of its use

Referring to Fig.l can be seen that the forearm interlocking nail according to the invention comprises of A square shaped nail (1) square nail of stainless steellt has rounded top (2) of 4.5-in diameter with a proximal hole(3) of 2.5 mm to 3.5 mm and 2cm, 3cm and 4 cm ^■ beneath entry tip (4) which is threaded from inside to engage the introducing Jig...

One distal hole (5) of lmm, approx 1.5 cm above the distal pointed tip (6). Nail for radius has the same features except bevelled distal end (7), the proximal hole

(8) is very near the entry tip and distal hole (9) is quite away from distal tip

The clip lock is very peculiar in its design. It has a U shaped arm (10) which is attached to short arm of L (11) and the long arm of L(12) is approximately 3cm long.

Fig.4. shows assembly of nail with instrumentation and jig Fig.5 shows application of the nail to a fracture of ulna

Fig.6 shoes application of nail to fracture of radius

Fig. 7 shows Pt positioning and pt preparation

Fig. 8 shows Entry point location

Fig. 9 shows Nail insertion Fig. 10 shows proximal interlocking

Fig. 11 shows distal interlocking a-Use carm image intensifier to verify placement in the centre of perfect circle b-After making an incision to bone and placing the kwire on bone centre the kwire within perfect circle with long axis of kwire perpendicular to long axis of nail. c-keep on verifying concentric positioning of k wire in the hole of nail alternatively can use two opaque rings. Drill thru bone d-After drilling, slide the straight marked kwire to read correct length of L arm of clip. e-insert clip and then rotate the U portion of clip to snugly fit it on the curvature of bone

Claims

I, Claim :

1. A forearm interlocking apparatus comprising of a nail component and clip component in which the nails has threaded entry tip, broadened to with proximal hole and a distal hole to receive specially designed clip lock which has a straight arm of L portion to engage in bone and nail and another arm broadly shaped as U to snugly fit the bone curvature.

2. The forearm interlocking apparatus as claimed in claim 1 wherein the shape of nail may vary from square, smooth, round, triangular or cloverleaf type and can be made of any Bioinert material such as stainless steel, titanium.

3. The forearm interlocking apparatus as claimed in claim 1 wherein broadened top can vary in size from 4.5 mm to 6.5 mm.

4. The forearm interlocking apparatus as claimed in claim 1 wherein proximal hole can vary in diameter from 2.5 mm to 3.5 mm and the distance of proximal hole from entry tip can vary from 2 cm to 4 mm for Ulnar nail and 1.5 cm for radial nail.

5. The forearm interlocking apparatus as claimed in claim 1 wherein the entry tip may be threaded on outer core and may have an end cap also.

6. The forearm-interlocking apparatus as claimed in claim 1 wherein the entry tip of nail may have a positive lock for secure fixation of nail to driver.

7. The forearm interlocking apparatus as claimed in claim 1 wherein distal hole can be anetroior posterior or mediolateral.

8. The forearm interlocking apparatus as claimed in claim 1 wherein the tip of nail may be pointed, bevelled, fluted of threaded.

9. The forearm interlocking apparatus as claimed in claim 1 wherein the clip lock may have sizes of 0.5 mm to 2 mm with a shape of L and broad U joint at short arm of L in which shape of U can be altered for better fitting on the curvature of bone.

10. The forearm interlocking apparatus as claimed in claim 1 wherein a jig made of any radiolucent material is present which comprises of one long L shaped arm wand on small L shaped arm jointed at 90 degree to each other and long portion of long L has holes at every cm and long portion of small L has 3 holes which corresponds to proximal holes of nail