AU2021245111A1 - Hard Wire Locking System Orthopaedic Frame - Google Patents

Abstract

This Hard Wire Locking System Orthopaedic Frame invention in the field of orthopaedic surgery discloses a system for attachment of an external frame to wires embedded in the bone. Attachment of pins to an external frame during surgery is a time consuming process and the thin wires used are subject to deformation. This invention discloses methods that decrease time in surgery and enhance the bone-wire-frame interface. The invention discloses hollow sleeves, with or without perforations, that clamp a thick wire. The resulting sleeve to wire join results in a strong union that enhances anchoring of wire pins to an external frame. The advantages are faster surgery and improved adjustment of the frame that results in enhanced bone healing. 1/3 Drawing 1 Cross Section View Aperture for wire pin End View

Description

1/3

Drawing 1 Cross Section View

Aperture for wire pin

End View

INVENTION TITLE: Hard Wire Locking System Orthopaedic Frame

INVENTORS: Gordon L. Slater Robert A. McPherson

APPLICANT: Integrant Pty Ltd, Double Bay, NSW, Australia

1 TECHNICAL FIELD

[001] External frames are used in the field of orthopaedic surgery. There are 2 pressing needs in the application of external frames, i. to simplify the application of the frame. ii. to prevent injury to the patient from exposed pins after application. This invention, as set out in the claims, addresses both these needs by the use of modified pins and end pieces for said pins.

2 BACKGROUND

[002] External frames are used in orthopaedic surgery to repair bone damage, correct deformities and allow bone and cartilage to rebuild (Antonios et al. (2019);Spiegelbergetal.(2010)). The frame is outside the body, hence "external", attached to the bone by thin metal pins. The external frame has the advantage over traditional methods in that it is a relatively non invasive procedure with less pain for the patient than open surgery. After application, the frame will stay on several weeks as the patients goes about their normal life. Gradual adjustment of the frame over this time achieves the desired correction to the bone.

[003] The procedure for applying the frame firstly drills metal pins through the bone of the patient. The pins are then attached to an external metal frame constructed around the limb. The frame design will vary greatly according to the defect being repaired. After surgery, the frame can then be slowly adjusted over weeks to gradually repair the underlying defect. As the frame is adjusted, the bone pins attached to the frame will also move. So the bone can be moved in the desired direction. As a gradual process it allows more controlled correction and less pain for the patient than open surgery.

[004] However it is a time consuming process to apply the frame. Thus there is a need for new inventions to increase the speed of application while maintaining control over bone modifications. The prior art outlines several pin clamps and other methods to improve external frame application (Cleveland et al, 2021; , but none provide a strong fusion between the wire and the clamp. Here we offer a new invention that further enhances the field of external frame application in patient care.

3 SUMMARY 3.1 TECHNICAL PROBLEM

[005] Applying an external frame in orthopaedic surgery is a complex and time consuming operation. But it has many advantages over invasive surgery, primarily it causes less pain for the patient than open surgery. Secondary, it means bone can be adjusted to repair by the surgeon as the patient goes about their normal life, giving finer control over the healing process. Therefore inventions that improve the application and performance of external frames are keenly sought.

[006] Pins that go through the bone are thin and deformable. So they have to be placed under high tension to prevent deformation. This takes time and specialised tools to create the tension. And the thin wires can cut into tissue as the frame is adjusted post operatively.

[007] As it is difficult to adjust fixed pin length precisely to the fixed size of the frame, one result of the operation can be sharp pin ends that can protrude from the apparatus. Both pin and frame are a fixed size, and rarely a perfect match. These sharp ends can damage clothing and cause skin damage. Clamps have been devised to hold and cover the pin end (Zandona et al. 2007; Chreene and Austin 2011; Murner al el. 2010) but the only solution prior to this invention was to cut the pins either before or after application of the external frame. Cutting the pin makes fitting more difficult and can leave an even sharper end from the cut.

3.2 SOLUTION TO PROBLEMS

[008] The solution to a thin pin that is deformable and requires tension is to use a thicker pin of at least 2 mm diameter. Thus tension is not required and there are significant time savings during surgery.

[009] Sharp pin ends can be covered by application of a hollow metal sleeve over the end of the pin. The sleeve can fit through holes n the frame that exist to aid construction of the frame. If the hollow sleeve has openings in the side, then the pin can be held in place by use of a bolt placed through a threaded hole in the external frame. The pressure of the bolt on the pin holds the pin in place through a friction mechanism, analogous to a Morse taper used in precision engineering. This taper forms a 3 point cold metal weld between pin, sleeve and bolt.

3.3 ADVANTAGEOUS EFFECTS OF INVENTION

[010] The advantages of this invention are

[011] i) time savings during surgery resulting in a) lower costs and b) reduced time that the patient is under anaesthesia.

[012] ii) reduced post operative skin damage as there are no sharp pin ends.

[013] iii) improved anchoring of the pin end and therefore post-operative adjustment of the frame is facilitated.

[014] iv) enhanced adjustment of the damaged bone due to the thicker wires and improved anchoring.

4 DESCRIPTION OF DRAWINGS

[015] Drawing 1. A cylindrical hollow wire sleeve for holding the bone pin on an external frame.

[016] Drawing 2. A hollow wire sleeve that has an opening on one side. The opening allows insertion of a bolt to hold the pin fixed on an external frame inside the sleeve.

[017] Drawing 3. A hollow wire sleeve with an opening on two sides. The opening allows insertion of a bolt to hold the pin on an external frame.

5 DESCRIPTION OF EMBODIMENTS

5.1 EXAMPLES

[018] Example A patient presents with a compound fracture of the tibia which has failed to heal with normal corrective procedures. Often failure to heal may be due to a complicating condition, such as diabetes. The patient undergoes surgical procedure under anaesthesia to apply an external frame. During the procedure thick metal pins (this invention) are placed through the tibial bone, such that they extend outside the lower leg on both sides. A circular frame is constructed around the lower leg, held together by bolts and adjustable "struts". Hollow sleeves (this invention) are placed over the ends of the pins. The sleeves are then attached to the external frame by bolts in the frame though holes in the sleeve. The 3 point cold weld of pin, sleeve and bolt form a close taper and hold the pin securely. Over several weeks after surgery the adjustable "struts" are extended or shortened, this causes the thick pins move and to shift the bone into a more normal position. The thick pins and cold weld of the sleeves enable the bone to be moved with more ease than current state of the art. Eventually the bones are correctly aligned and begin to heal so the frame and pins can be removed.

6 CITATION LIST 6.1 PATENT LITERATURE

[019] Chreene and Austin (2011) Aust Patent App 2011282634 Double action external fixation clamp

[020] Cleveland et al. (2021) Aust. Patent App. 2020203734 Prosthetic implants including a frame for fixation to bone and related methods.

[021] Murner et al., (2010) Aust Patent App 2010203309 External fixation component

[022] Mullaney (2020) Aust Patent App 2020200044 External Bone Fixation Systems.

[023] Zandona et al. (2011) Aust Patent App 2011358377 Clamp for temporary or definitive external orthopaedic fixation, and external fixation system comprising said clamp

6.2 NON-PATENT LITERATURE

[024] Antonios, T. et al. (2019). A Systematic Review of Patient-reported Outcome Measures Used in Circular Frame Fixation. Strategies Trauma Limb Reconstr 14, 34-44.

[025] Spiegelberg, B. et al. (2010). Ilizarov principles of deformity correction. Ann R Coll Surg Engl 92, 101-105.

Claims (1)

1. Claim 1 A cylindrical hollow wire sleeve for holding the bone pin on an external frame as illustrated in Drawing 1.

   Claim 2 A hollow wire sleeve of any external shape for holding the bone pin on an external frame similar to that as illustrated in Drawing 1. For example a rectangular or hexagonal external shape but not limited to these shapes.

   Claim 3 A hollow wire sleeve that has an opening on one side for insertion of a bolt to hold the pin fixed on an external frame inside the sleeve as illustrated in Drawing 2

   Claim 4 A hollow wire sleeve of any external shape that has an opening on one side. The opening for insertion of a bolt to hold the pin fixed on an external frame inside the sleeve, similar to that illustrated in Drawing 2. For example a rectangular or hexagonal external shape but not limited to these shapes.

   Claim 5 A hollow wire sleeve with an opening on two sides that allows insertion of a bolt to hold the pin on an external frame fixed as illustrated in Drawing 3

   Claim 6 A hollow wire sleeve of any external shape with an opening on two sides. The openings allow insertion of a bolt to hold the pin on an external frame fixed, similar to that illustrated in Drawing 3. For example a rectangular or hexagonal external shape but not limited to these shapes.

   Claim 7 A hollow wire sleeve for holding the bone pin on an external frame as illustrated in Drawing 1. With any number of holes or perforations in the sleeve.

   Claim 8 Use of a thicker wire of at least 2 mm diameter to insert through bone and attached to an external frame.