GB2431109A - Mouldable surgical pin protector - Google Patents

Abstract

An end protection cap 2 for a surgical pin, wire or screw 1 which is moulded in situ around the exposed end of the pin 1 and sets rigidly. Preferably the cap 2 may be formed from any mouldable or settable material and may be remoulded by applying heat. A locking device such as a washer or screw may be embedded within the mouldable material. The cap 2 may be used with a dressing retention device 7 or skin pressure protection device. The mouldable material may incorporate drug release agents, pH modifying agents or degradable materials and may also be made into novelty shapes. A protective cover may be attached to the moulded cap 2. The cap 2 may be used with any surgical pin.

Description

Surgical Pin Protector and system

Summary

The present invention relates to a mouldable cover used to protect the end of surgical wires, pins or screws.

Background

US3 809075 1974 MATLES A. Describes a formed retainer with split halves US4688560 1987 SCHULTZ ROBERT J. Describes a cap with a coned metal spring W09305736 1993 GORDON DONN M. Describes a cylindrical cap from metal sheet with longitudinal split FR2 707863 1995 CLAUDE BARBA JEAN. Describes a cap for threaded pin.

EP078 7467 1997 KEHYAYAN. Describes an elastic cover with internal push on lockable element.

US5752952 1998 ADAMSON PAUL H. Describes a surgical pin shield contoured to fit to the patients limb or digit.

US5766005 1998 CASEY KEVIN M. Describes a cap assembly for twisted oral ligature wire.

US20020071 85 2002 AGHION MICHAEL. Describes a spherical pin ball with threaded hole and grub screw.

US2003018333 2003 KOKESH FRITZ C. Describes a rigid pin cover with deformable lower portion that contacts patient skin.

US200321 5307 2003 MARKIEWITZ ANDREW. Describes a cylindrical push fit cap with internal shaft retention washer.

WO03028565 2003 ALAN WARWICK. Describes a surgical pin guard with adhesive coated opposable wings that can be snapped around the bent end of a pin.

DE60200489T 2005 DELMI MARINO. Describes a surgical pin with protective plug with locking device A range of covers (detailed above) have been used to protect the ends of surgical pins, wires and screws that may protrude through the skin when they are used in percutaneous mode to stabilise fractures or bone fusion sites. The majority of these prior devices have been pre-fabricated caps, covers or sleeves specifically tailored for an individual type of surgical wire or pin. Where used as a generic cover to fit smooth pins of different diameters then locking mechanisms have been incorporated within the cover to engage with the cut- offend of the surgical pin. These mechanisms have commonly been grub screws, flanged retention washers or coned springs.

These devices are all pre-fabricated and suffer from either being specific to one type of surgical pin or have to be made in a range of sizes when used with pins of different diameters. The high cost involved with the manufacture of a single use disposable device has limited their widespread adoption in clinical practice. Because of this more traditional techniques such as covering the pin end with soft bandaging, rubber bungs or elastoplast strapping are still commonly employed. These caps tend to be dislodged and fall off or become soiled.

Statement of Invention

There is a need therefore to develop a versatile, adaptable and economic solution to the problem of providing cover of percutaneous surgical pins in their common modes of application. This invention solves this problem.

The proposed invention employs a pin cover system based upon a thermoplastic polymer material that can be custom moulded to any shape, form or diameter and thus be used universally with any surgical pin. Embodiments of the invention incorporate conformable skin protectors that shield pressure from migrating pin heads, locking devices that are moulded within polymer to gain attachment to the shaft of surgical pins and mouldable forms to hold dressing materials and such like.

Introduction to Drawings

An example of the invention will now be described by referring to the accompanying drawings: FIGURES 1 to 6 show the surgical pin cover designs and incorporated retention mechanisms.

FIGURES 7 to 9 illustrate the use of the pin cover systems applied to pins stabilising a forearm fracture.

FIGURE 10 illustrates the 3 dimensional configuration of the pin cover system

Detailed Description of Invention

The pin cover system is founded on the principle of embedding the surgical pin end within a polymer that may be moulded into any desirable shape or form. Retention devices applied to the surgical pin during the moulding stage help lock the pin cover in place.

The particular nature of the polymer or polymer composite employed should preferentially have the following properties.

1) It should be hand mouldable into a variety of forms to complement the size and shape of surgical pin devices.

2) Once moulded on surgical pins it should become rigid.

3) When rigid it should possess necessary mechanical properties to remain firmly attached to surgical pins 4) It should be chemically and thermally stable at room temperatures and in normal environments.

5) It should be non-toxic and non-allergenic.

A suitable polymer is polycaprolactone, a thermoplastic made from the polymerisation of epsilon caprolactone. This polymer satisfies the above properties, becomes translucent and easily mouldable over 60 degrees centigrade. It is a rigid opaque solid at ambient room temperature. Homopolymer preparations have tensile strengths of between 3500-6000 MPa and Shore hardness of 55D. It has low acute oral toxicity (LD50> 8000mg/kg) and low dermal toxicity (LD5O >1600 mg/kg) and has been widely used in in vivo implantable situations. It is degraded by soil bacteria thus if dislodged and lost should degrade by natural means.

In a typical clinical situation the exposed end of a fixation wire, pin or screw is left proud of the skin or percutaneous site. An appropriate amount of polymer is moulded around the exposed end of the surgical pin, is shaped and allowed to rigidly set adhering to the end of the pin. The smooth nature of the surface of the rigid polymer will minimise snagging on clothes, shoeware or other objects. Trauma to adjacent skin, digits or limbs will be lessened. The chances of pin migration, deep penetration beneath skin surface or accidental removal will be lessened. The shape, size and form of the applied polymer is infinitely variable and determined mainly by the site of pin application.

In its simplest design and mode of application the polymer is moulded around the bent end of the pin 1 to form a smooth roughly spherical pinball 2. The shape, size and surface profile can be custom moulded to suit the particular clinical application, body region or size of patient.

Locking retention devices (3, 4, 5) to promote fixation of the polymer cover to the shaft of a pin 1 can first be applied to the pin 1 and then embedded within polymer 2.

One such device consists of an internal shaft retention washer 3 or washers 4 applied over the shaft of the pin 1. The washer teeth engage with the surface of the pin shaft.

During moulding of the polymer cover 2 around the retention washer 3, manual compression helps to deform the teeth of the washer 3 promoting engagement with the pin shaft 1.

Another device incorporates a set screw 5 moulded within the polymer cover 2. Once polymer is solid the set screw 5 can be manually tightened, the pitch of the screw 5 allowing its tip to engage with the shaft of the pin I helping to lock the polymer cover 2 in place.

Another device incorporates a set screw S engaged within a threaded sleeve 6. Both set screw 5 and sleeve 6 are moulded within the polymer cover 2. The shaft of the surgical pin passes through a hole in this sleeve 6. The rigid threaded walls of the sleeve increase the security of the grip of the set screw 5.

Another component of the pin protector system employs custom mouldable polymer sheets, pads or surfaces 7 beneath the polymer cover 2. These can be conformed to match the contour of the underlying skin 8 or body surface in order to control the distribution of pressure from the cover 2. This reduces the risk of pressure necrosis should pins be driven further into the body. It also allows the facility to control and stabilise skin and pin site dressing materials and wound dressings 9.

Another embodiment of the pin protector system employs mouldable polymer plates contoured to conform to the body surface that can be moulded onto the polymer covers 2. These can serve to jointly protect, connect and cover adjacent surgical pins I, to provide support for wound dressings 9. This system can either protrude through or support overlying plaster casts or orthotic splints.

In all of the above embodiments the moulded polymer cover 2 has sufficient mechanical strength and hardness to resist breakage, fracture and remain firmly attached to the end or shaft of the surgical pin 1. Furthermore once the pin I has served its purpose the attached cover 2 can facilitate manual extraction or removal.

In case of covers 2 being accidentally broken, detached or wrongly sited then the polymer material can be reapplied or easily remoulded by the application of heat from a heat gun or immersion in warm saline or water.

In a further embodiment the covers 2, surfaces 7 and plates 10 may be colour encoded, date stamped or marked with implant identification tags.

In a further embodiment the mouldable polymer cover 2, polymer sheet or wound dressing retaining plate 7 may incorporate materials that provide controlled release of drug agents such as topical antibiotics, wound dressing agents or chemicals that modify the pH of the adjacent skin surface. The mouldable cover 2 itself may also be shaped to capture or hold such a dressing material around the base of the surgical pin or stabilise the dressing material against skin or wound surface 10.

This invention is not limited to the use of a specific polymer. The principles of the invented system can be extended to use other mouldable thermoplastics or plastics composites. Chopped carbon fibre or particulate materials may be incorporated with polymer. These may enhance the structural properties of the pin covers or promote material degradation once discarded. Coloured dyes may also be introduced.

In a final embodiment that may be particularly suited for children the mouldable polymer may be provided in the form of motifs, cartoon characters, animal shapes and such like.

It will be apparent to those skilled in the art from the foregoing description and accompanying drawings that additional modifications and/or changes of the disclosed embodiments may be made without departure from the invention. Accordingly, it is expressly intended that the foregoing description and accompanying drawings are illustrative of preferred embodiments only, not limiting, and that the true spirit and scope of the present invention be determined by reference to the appended claims.

Claims (1)

1) A system consisting of a material that can be moulded to conformably attach and set rigidly to the exposed end or shaft of a surgical pin, wire or screw that is positioned in-situ within a patient.

2) The device claimed in Claim 1 is formed from any type of mouldable or

settable material

3) The device claimed in Claim I is formed from any material that can be remoulded by the application of heat.

4) The device claimed in Claim 1 incorporates a locking device set within the mouldable material 5) The locking device of Claim 4 being an internal retention washer or washers.

6) The locking device of Claim 4 being a set screw.

7) An embodiment in which the device of claim 1 is used with a dressing retention device made from the same material as claim 1.

8) An embodiment in which the device of claim 1 is used with a pressure protection component made from the same material as claim 1.

9) An embodiment in which protective covers can be attached to the mouldable material of claim 1.

10) An embodiment in which the mouldable material of claim I can incorporate drug release agents.

11) An embodiment in which the mouldable material of claim I can incorporate pH modifying agents.

12) An embodiment in which the mouldable material of claim 1 can incorporate degradable particulate materials or fillers.

13) An embodiment in which the mouldable material of claim I can be conformed into a novelty shape.