WO2017037733A1

WO2017037733A1 - External fixator for trauma management of limb

Info

Publication number: WO2017037733A1
Application number: PCT/IN2016/000218
Authority: WO
Inventors: Kumar Kanojia Rajendra
Original assignee: Kumar Kanojia Rajendra
Priority date: 2015-08-28
Filing date: 2016-08-26
Publication date: 2017-03-09
Also published as: WO2017037733A4

Abstract

The fixator of the present invention comprises multiple plates which are triangular in shape and can be assembled and de-assembled any time anywhere making fixation and removal of this fixator quite easy. The plates are of different lengths and widths with threaded holes at multiple positions. The inventor has also provided threaded rods of varying length which can be inserted in the threaded holes of triangular frame to make it stable. The proposed fixator is simpler in design and eliminates the need of change of wire for tensioning and re tensioning, tightening of nut and bolts or ring. Rods in the present invention can be threaded at any threaded hole in the plate as per the requirement. Changing of pin position is easy in plate and rod design of the present invention. For the distraction and compression, one distraction and compression device would be applied between the site corticotomy.

Description

EXTERNAL FIXATOR FOR TRAUMA MANAGEMENT OF LIMB

FIELD OF THE INVENTION

The present invention relates to orthopedic medical devices. More particularly the invention pertains to an external fixator for trauma management of limb, suitable to treat a myriad of bone and soft tissue pathologies.

BACKGROUND OF THE INVENTION

Fixators are biomedical devices comprising of pins and rods which help in fixing or lengthening of limbs.

In order to understand the invention better, one has to distinguish between internal fixators and external fixators and types of these fixators.

Interna] Fixator is an operation in orthopedics that involves the surgical implementation of implants for the purpose of repairing a bone. An internal fixator may be made of stainless steel or titanium.

Open Reduction Internal Fixation (ORIF) involves the implementation of implants to guide the healing process of a bone as well as the open reduction or setting of the bone itself.

Closed Reduction Internal Fixation (CRIF) is reduction without any open surgery, followed by internal fixation.

External fixation is a surgical treatment used to stabilize bone and soft tissues at a distance from the operative or injury focus. External fixators provide unobstructed access to the relevant skeletal and soft tissue structures for their initial assessment and also for secondary interventions needed to restore bony continuity and a functional soft tissue cover.

External fixation has evolved from being used primarily as a last resort fixation method to becoming a main stream technique used to treat a myriad of bone and soft tissue pathologies. Techniques in limb reconstruction continue to advance largely as a result of the use of these external devices. A thorough understanding of the biomechanical principles of external fixation is useful for all orthopedic surgeons as most of them occasionally mount a fixator throughout their career.

We limit our discussion to External Fixators only. USEFULNESS OF EXTERNAL FIXATORS:

1. Stabilization of severe open fractures

2. Stabilization of infected nonunion

3. Correction of extremity mal-alignments and length discrepancies

4. Initial stabilization of soft tissue and bony disruption in poly trauma patients (damage control orthopaedics)

5. Closed fracture with associated severe soft tissue injuries

6. Severely comminuted diaphyseal and periarticular lesions

7. Temporary transarticular stabilization of severe soft tissue and ligamentous injuries

8. Pelvic ring disruptions

9. Certain pediatric fractures

10. Arthrodesis

1 1. Ligamentotaxis

12. Osteotomies

Already available external fixators and their limitations

Various types of external fixators and their common clinical applications are described with a focus on unilateral and circular frames. The biomechanical principles that govern bony and fixator stability are reviewed as well as the recommended techniques for applying external fixators to maximize stability.

Method of use

Installation of the external fixator is performed in an operating room, normally under general anesthesia. Removal of the external frame and bolts usually requires special wrenches and can be done without anesthesia. In this kind of reduction, holes are drilled into uninjured areas of bones around the fracture and special bolts or wires are screwed into the holes. Outside the body, a rod or a curved piece of metal with special ball-and-socket joints joins the bolts to make a rigid support. The fracture can be set in the proper anatomical configuration by adjusting the ball-and-socket joints. Since the bolts pierce the skin, proper cleaning to prevent infection at the site of surgery must be performed.

External fixation is also used in limb lengthening. People with short limbs can have, for example, legs lengthened. In most cases the thigh bone (femur) is cut diagonally in a surgical procedure under anesthesia. External fixator pins or wires (as above) are placed each side of the 'man made fracture' and the external metal apparatus is used to very gradually push the two sides of the bone apart millimeter by millimeter day by day and week by week. Bone will gradually grow into the small gap created by this 'distraction' technique. Such a process can take many months.

In most cases it may be necessary for the external fixator to be in place for many weeks or even months. Most fractures heal in between 6 and 12 weeks. However, in complicated fractures and where there are problems with the healing of the fracture this may take longer still. It is known that bearing weight through fracture by walking on it, for example, with the added support of the external fixator frame actually helps fractures to heal.

(Ref: Wikipedia)

Types of external fixators:

External fixators are presently used in orthopedics and in plastic surgery. These can be categorized into unilateral and circular frames.

Unilateral frames are positioned on one side of the limb. Unilateral frames allow the limb to remain functional, avoid complications, and provide bony stability.

When we consider unilateral frames, the two most common designs are:

a) The bulkier monobody designs (EBI, Parsippany, NJ, USA, and Orthofix, Verona, Italy)which have considerable intrinsic stability owing to their heavy and rigid design and

b) The trauma type pin-to-bar fixators which use multiple lightweight carbon fiber rods to provide stability.

c) Hybrid external fixators with a ring attached and behave like monobody designs. The stability of all unilateral frames is improved by the use of larger-diameter half pins with more points of fixation, decreasing the distance between the frame and the bone, and placing pins out- of-plane to one another. Circular frames are spatial in nature and cover the bone in a circular manner. Some of the commonly used circular frames are

• Ilizarov apparatus

• Taylor Spatial Frame

• Hoffmann external fixation system

· Rail external fixator

The classic circular frame is the Ilizarov external fixator that has now been integrated with the newer Taylor Spatial Frame (TSF; Smith and Nephew, Memphis, TN, USA). The basic components of this frame are rings, connecting rods, and struts. Varieties of Ilizarov rings include full (closed) rings, partial (open) rings, or arches. A full ring provides the most stability, and arches the least. However, partial rings and arches are helpful near joints and in areas where a closed ring would prevent normal extremity function or positioning. A partial ring is commonly used around the proximal knee to allow for improved knee flexion. Open rings and arches are also used around the shoulder and proximal femur where a full ring would not fit comfortably. Limitations of existing fixators

Since external fixator needs schanz pin, connecting rods and Clamps inserted in the patient's body, infections in the limb are a common problem. Most common complications are:

Pin site infection which responds well to aggressive local pin care and empiric oral antibiotics or culture-specific antibiotics are used. At times, advanced infections are aggressively treated with removal of the pin or wire. Rarely, operative intervention is needed for pin infections to replace an important pin or debride osteomyelitic bone.

Malunion has been a commonly reported complication for fracture treatment with fixators. Septic arthritis may complicate any patient being treated with fixators. Deep vein thrombosis is a complication that accompanies any lower extremity surgery.

Although the fixator protects the bone that it spans, it creates a stress riser in the adjacent bone that is not within the frame. This situation can lead to fractures around the frame. Often, this occurs through the most proximal or most distal screw hole. Once the frame has been removed, stress fractures may occur through any of the screw holes before they have had a chance to remodel.

Stiffness of adjacent joints occurs if the joint has been spanned for some time and during lengthening procedures. The ankle joint tolerates this immobility far better than the knee joint. When trauma fixators are used to stabilize tibia fractures, strong consideration should be given to initially including the foot (spanning the ankle joint) to prevent the development of an early equinus contracture. Once the patient is more mobile and pain-free, the foot ring is removed, allowing for ankle motion and easier weight bearing. INNOVATIVE SOLUTION PROPOSED BY THE INVENTOR

We restrict our invention to open fractures that have significant soft tissue disruption (e.g., type II or III open fractures) such as soft tissue injury (e.g., burns) , Acetabular and pelvic fractures or severely comminuted and unstable fractures, fractures that are associated with bony deficits Limb- lengthening procedures or fractures associated with infection or nonunion. The inventor being a doctor himself, has developed and designed an external fixator which is more stable, surgeon and patient friendly and is low cost also. Keeping in mind the fact that more the number of pins being inserted into the limb, more are the chances of infection , the inventor has developed an external fixator which needs very less insertion of pins and screws inside the body of the patient . Maximum stability to the fixator is provided using components at the body of the fixator and not within the body of the patient.

The fixator of the present invention comprises three L shaped slotted plates (with 60° bend) comprising numerous holes with threading for adjusting height and adjustable clamps with pins. These plates can be assembled and de-assembled any time anywhere making fixation and removal of this fixator quite easy. The inventor has also provided threaded rods of varying length which can be inserted in the threaded holes of triangular frame to make it stable. Thereby number of pins and screws which needed to be inserted inside the body of the patient to stabilize the fixator is very less as compared to circular fixator of any kind. Chances of vascular injury are few as the rod is not crossing the surface of the limb between the neurovascular structures.

Triangular frame is more stable as compared to circular frame. Placing the limb on bed with a triangular frame is easier than with a circular fixator.

The proposed fixator is simpler in design and eliminates the need of change of wire for tensioning and re tensioning, tightening of nut and bolts or ring. Need for long rods for construction of equally long frame for one ring is also eliminated as rods in the present invention can be threaded at any threaded hole in the plate as per the requirement. Changing of pin position is easy in plate and rod design of the present invention.

For the distraction and compression, one distraction and compression device would be applied between the site corticotomy.

Further to this, since the fixator is very stable due to its triangular shape and very few components are inserted inside the limb, during the process of recovery or in long follow ups, chances of frame deformation are reduced.

As is obvious now, the external fixator of the present invention finds application in:

1. Patient with compromised immune system

2. Non-compliant patient who would not be able to ensure proper wire and pin care

3. Pre-existing internal fixation that prohibits proper wire or pin placement

4. Bone pathology precluding pin fixation

PRIOR ART PATENTS

S.No. Prior Patent Present invention

1. Tenxor external fixation system The present invention does not contain (STRYKER): Describes an External complex attachments as mentioned in Fixator for peri and intra-articular prior art rather it disclose a simple, fractures. It comprises wires, Half Pins, small and compatible three L shaped wire post, pin post, Hoffmann II clamp slotted plates (with 60° bend) and a circular carbon ring with a comprising numerous holes with unilateral or modular frame fixation. threading for adjusting height and adjustable clamps with pins.

2.

Large External Fixator -Delta Frame The present invention disclose a Ankle Bridge: Describes delta shaped triangular shaped fixator for bones with fixator for distal tibia comprising clamps, slots for height adjustment. It consists Steinmann pin, screws, multi-pin clamp of three L shaped slotted plates (with with rod attachment, carbon fiber rods. It 60° bend) comprising numerous holes is very complicated having many with threading for adjusting height and components and require fixation adjustable clamps with pins. It is instruments. simple, patient friendly and does not require complicated fixation aids.

3. AO ASIF Fixator: Describes a tubular The present invention disclose a fixator which includes tubular triangular shaped fixator which does connecting rod, half pins, long thread not comprise rods as suggested in prior and short thread, single adjustable art rather it includes three L shaped clamp, universal clamp and a slotted plates (with 60° bend) compression apparatus. comprising numerous holes with threading for adjusting height and adjustable clamps with pins.

4. TransFx® External Fixation System The present invention disclose a a Large and Intermediate Surgical circular toroid shape as mentioned in Technique: Describes an external prior art rather it comprise a triangular fixation system which includes pins (self- shaped fixator which includes three L drilling, self-tapping, trocar tip, central shaped slotted plates (with 60° bend) threaded), rods (8mm diameter, 1 1mm comprising numerous holes with diameter), clamps (pin-to-rod clamps, threading for adjusting height and adjustable clamps and transition clamp), adjustable clamps with pins.

multi-pin clamps and carbon fiber rods

with rounded ends.

US8177818 B2: Describes a fixation The present invention does not disclose plate with a base section including merely a fixation plate rather it disclose apertures for fixation to one bone a three L shaped slotted plates (with 60° segment and a leg section extending from bend) comprising numerous holes with the base section and including threading for adjusting height and apertures for fixation to another bone adjustable clamps with pins.

segment.

US4784125 A: Describes a partial or full The present invention does not disclose circular toroid external fixation device a circular toroid shape as mentioned in which includes spacing web connecting prior art rather it comprise a triangular opposed inner and outer polygonal- shaped fixator which includes three L shaped clamping rims , two opposed and shaped slotted plates (with 60° bend) symmetrical polygonal portions, joined comprising numerous holes with by a web serving to connect and space threading for adjusting height and apart the polygons. The polygonal adjustable clamps with pins.

portions are preferably triangular

portions.

US5776132A: Describes an external The present invention does not disclose fixation assembly comprising two rods and ring like structure rather it connecting rods, ring-like arcuate having disclose a triangular shaped fixator a plurality holes therethrough, pins and which includes three L shaped slotted wires. plates (with 60° bend) comprising numerous holes for adjusting height and adjustable clamps with pins.

8. CN203425013 U: Describes Ring type The present invention does not disclose triangular synchronous control extender Ring type triangular synchronous for thigh bone composed of an extender control composed of an extender frame frame body, a steel needle fixing clip body, extending rods rather it disclose connected onto the extender frame body a triangular shaped fixator which and steel needles clamped in the steel includes three L shaped slotted plates needle fixing clip. The bone extender (with 60° bend) comprising numerous frame body comprises a bone lower hole holes for adjusting height and ring, a bone upper hole ring arranged adjustable clamps with pins

above the bone lower hole ring and a

plurality of fast drawing extending rods

connected between the bone lower hole

ring and the bone upper hole ring.

PRIOR PUBLICATIONS:

A lot of articles as below have been reviewed to find out if a similar solution as proposed by the inventor is suggested or is available. 1. Rozbruch SR, llizarov S, Blyakher A (2005) Knee arthrodesis with simultaneous lengthening using the llizarov method. J Orthop Trauma 19:171-179

2. llizarov GA (1992) The Apparatus: components and biomechanical principles of application. In: Green S (Ed) Transosseus osteosynthesis. Theoretical and clinical aspects of the regeneration and growth of tissue. Springer-Verlag Berlin, pp 63-136Goodship AE, Watkins PE, Rigby HS, et al (1993) The role of rigid frame stiffness in the control of fracture healing. An experimental study. JBiomech 26:1027-1035

3. Rozbruch SR, Helfet DL, Blyakher A (2002) Distraction of hypertrophic nonunion of tibia with deformity using Ilizarov/T aylor spatial frame. Arch Orthop Trauma Surg 122:295—298 [PubMedJ Thus, none of the patents or patent applications or publications in the prior art describes the fixator of the present invention which can be said to anticipate the present invention.

OBJECTS OF THE INVENTION

It is an object of the invention to disclose a novel external fixator for fixation and reconstruction of the fractures of limbs or lengthening of limbs which needs only a few pins and rods to be inserted in the patient's body and is still very stable.

One more object is to disclose a novel external fixator which can overcome the drawbacks of existing available fixators, is doctor friendly as well as patient friendly. Yet another object of the invention is to disclose an external fixator which eliminates the need of change of wire for tensioning and re tensioning, tightening of nut and bolts or ring.

One more object of the invention is to disclose an external fixator which eliminates the need for long rods for construction of equally long frame and in which changing of pin position in plate is easy. Yet another object of the present invention is to disclose an external fixator which uses a single device for distraction and compression between the site corticotomy.

SUMMARY OF THE INVENTION

The fixator of the present invention comprises three L shaped slotted plates (with 60° bend) comprising numerous holes with threading for adjusting height and adjustable clamps with pins. These slotted plates can be assembled and de-assembled any time anywhere making fixation and removal of this fixator quite easy. The inventor has also provided threaded rods of varying length which can be inserted in the threaded holes of triangular frame to make it stable.

The proposed fixator is simpler in design and eliminates the need of change of wire for tensioning and re tensioning, tightening of nut and bolts or ring. Rods in the present invention can be threaded at any threaded hole in the plate as per the requirement. Changing of pin position is easy in plate and rod design of the present invention. For the distraction and compression, one distraction and compression device would be applied between the site corticotomy. Further to this, since the fixator is very stable due to its final triangular shape instead of circular and very few components are inserted inside the limb, during the process of recovery or in long follow ups, chances of frame deformation are reduced.

Such a fixator with all the components described above has not been described anywhere in the prior art, to the best of knowledge of the inventor.

DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig. la: Schematic diagram depicting a prior art plate (Tenxor external fixation system (STRYKER))

Fig. lb: Schematic diagram depicting a prior art plate (Large External Fixator -Delta Frame Ankle Bridge)

Fig. lc: Schematic diagram depicting a prior art plate (AO ASIF Fixator)

Fig. 2a: Schematic diagram depicting a prior art plate (TransFx® External Fixation System Large and Intermediate Surgical Technique)

Fig. 2b: Schematic diagram depicting a prior art plate (US8177818 B2)

Fig. 2c: Schematic diagram depicting a prior art plate (US4784125 A)

Fig. 2d: Schematic diagram depicting a prior art plate (US. Pat. No. US5776132A)

Fig. 3a: Combination of assembly of the fixator of present invention

A: Screw hole

B: One rod

C: Hole

D: Another rod Fig 3 bl: View 1 of one unit of fixator of present invention

PI: Plate 1

P2: Plate 2

P3: Plate 3

C: Connecting rod Fig 3 b2: View 2 of one unit of fixator of present invention

A: One assembly

B: Three plates in triangular assembly

PI: Plate 1

P2: Plate 2

P3: Plate 3

C: Connecting rod

Fig 3c: Plates with threaded holes, threaded rod, threaded connecting bolt and different Length plates

A: Threaded rod

B: Plate with holes

C: Threaded bolt

D: Fixator assembly with multiple plates

Fig 3 d: Triangular structure and plates

A: Stable triangular construction of fixator

B: Different sized flat plates Fig 3e: Compression and Depression Unit

Fig 3f: Views of L shaped plate with 60° bend and final fitting on limb

A: View 1 of L shaped plate with 60° bend

B: View 2 of L shaped plate with 60° bend

C: View of Stable triangular construction of fixator on limb

DETAILED DESCRIPTION OF THE INVENTION

The invention is now described in detail with reference to its various elements and also supporting drawings. It comprises:

I) Three L shaped slotted plates with 60° bend (B of Fig 3c) comprising threaded screw holes (A, B, C of Fig 3a). II) Threaded rods (A of Fig 3c) for height and length adjustment.

II) Normally used adjustable clamps with pins (Fig 3 c).

These slotted plates (B of Fig 3c) can be assembled and de-assembled any time anywhere making fixation and removal of this fixator quite easy. The inventor has also provided threaded rods (A of Fig 3c) of varying length which can be inserted in the threaded holes (A, B, C of Fig 3a).

All the three L shaped slotted plates are fixed in a triangular manner (Fig 3a) with the help of threaded rods which pass through threaded screw holes of L shaped slotted plates with 60° bend (B of Fig 3c) and are tightened using normally available adjustable clamps and pins so that these together make an equilateral triangular shaped frame along the limb.

The fixator of present invention is simpler in design and eliminates the need of change of wire for tensioning and re tensioning, tightening of nut and bolts or ring. Rods in the present invention can be threaded at any threaded hole in the plate as per the requirement. Changing of pin position is easy in plate and rod design of the present invention. For the distraction and compression, one distraction and compression device would be applied between the site corticotomy.

Further to this, since the fixator is very stable due to its final triangular shape instead of circular and very few components are inserted inside the limb, during the process of recovery or in long follow ups, chances of frame deformation are reduced.

For the application of external fixator between the fracture ends, in open fractures of different grades of fractures according to various classifications, when old conventional fixators were used, the first step is to make a frame for the fixator. But while using the fixator of the present invention, one has just to choose three long plates (B of Fig 3 c) according to the length of the limb where fixator has to be applied. No frame making is to be done before hand. Second step in the present invention is to fix the plates with threaded rods inside the plane of bone, at right angle. Final and third step is to apply the frame of plates along the limb.

For the application of external fixator in lengthening purpose corticotomy, it will be done at the proximal and distal half of the limb between two rods. First step is to apply one distraction compression unit (CD unit) between two rods and the rest fixing of the frame remains the same as above. Compression and distraction may be done as per need at the speed of one millimeter per day. Normally practiced follow-up would be at every fifteen days, radiographs will be taken, once the union is seen as the callus formation, union is present as patient could walk normally, radiological union when patients radiograph is showing bony union.

The factors relating to novelty aspect, inventive step and also industrial application of the invention are duly elaborated below.

Novelty aspect of the invention: The present invention discloses a novel, external fixator, the like of which has not been described in the prior art. The currently available fixators are difficult to use and cause various complications in the patient due to insertion of multiple pins and screws in the patient body. The available structures being circular are not stable and positioning the limb on the bed is very painful owing to the circular shape of the fixator. The fixator of the present invention is triangular in shape, has lesser number of components which need to be inserted in the body of the patient and thus reduces the risk of infections.

Inventive step: The inventive step lies in the unique manner in which the circular fixator is replaced by a triangular fixator. This has been achieved by inventing plates are of different lengths and widths with threaded holes at multiple positions. The inventor has also provided threaded rods of varying length which can be inserted in the threaded holes of triangular frame to make it stable. The inventor being an orthopedic surgeon has taken care of every aspect of fixator including the device used to fix and remove it.

Industrial application: The plate is capable of manufacture at industrial level as all its elements are well-defined and capable of reproduction in a scientific manner.

In the preceding detailed description, the invention has only been described in an exemplary manner. Various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than in restrictive sense. Thus, without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

I CLAIM:

1. An external fixator for trauma management of limb consisting :

Three L shaped slotted plates with 60° bend (B of Fig 3c) in each and each plate having threaded screw holes (A, B, C of Fig 3a);

Threaded rods (A of Fig 3c) for height and length adjustment and

Normally used adjustable clamps with pins (Fig 3 c)

WHEREIN

- The plates with threaded holes and rods (Fig 3 c) are fixed inside the plane of bone, at right angles;

- All the three L shaped slotted plates are fixed in a triangular manner (Fig 3a) with the help of threaded rods which pass through threaded screw holes of L shaped slotted plates with 60° bend (B of Fig 3c) and are tightened using normally available adjustable clamps and pins so that these together make an equilateral triangular shaped frame along the length of limb;

- Number of pins and rods passing through the limb is minimal and

Stability to the fixator is provided by fixing components such as clamps and connecting rods, at the body of the fixator itself and not within the body of the patient.

2. The external fixator for trauma management of limb as claimed in claim 1 WHEREIN the need of change of wire for tensioning and re tensioning, tightening of nut and bolts or ring is eliminated.

3. The external fixator for trauma management of limb as claimed in claim 1 WHEREIN at rest position on bed, the limb rests on plain surface in a natural manner after fixing the fixator due to one surface of the equilateral triangular shaped frame resting horizontally on bed.

4. An external fixator for lengthening of limb WHEREIN: - One distraction and compression device is applied between the proximal and distal half of the limb between two threaded rods;

- Number of pins and rods passing through the limb is minimal and

1. The external fixator for trauma management of limb as claimed in claim 1 WHEREIN the number of threaded screw holes and threaded rods varies as per the size of the fixator.

2. The external fixator for trauma management of limb as claimed in claim 1 WHEREIN the number of pins and rods passing through the limb varies as per the requirement to achieve maximum stability of the frame with minimum invasion in limb.