IE43291B1 - Orthopaedic staples - Google Patents

Description

Orthopaedic staples in current surgical usage are of a conventional fiprffl consisting of an elongate metal member having a generally ll-shape with the free end portions of its arms uniformly tapered. Such staples are employed for various purposes, one purpose being to secure adjacent fragments of a fractured bone in a desired relationship while the fragments re-unite. However, these staples do not, in themselves, exert any compressive forces between the bone fragments in a transverse direction relative to the staple arms. This is disadvantageous insofar as bone fragment union is speeded by compression and there is an increasing recognition of this factor in fracture fixation techniques.

According to the present invention there is provided an orthopaedic staple comprising an elongate member of biocompatible metal formed to a generally U-shape with parallel arms, the free end portions of said arms being tapered predominantly on their mutually facing surfaces, said arms being formed with retraction-resisting barbs by notches in said facing surfaces, and the staple being of sufficiently greater rigidity relative to bone to be substantially unyielding in shape when penetrated into bone to bridge a fracture, whereby such penentration exerts compressive force across said fracture to reduce the same by the action of said tapering, and bone material is urged into said notches by said force.

Normally the free end portions of both arms will be tapered only on their mutually facing surfaces and wholly across their respective widths.

One embodiment of an orthopaedic staple according to the invention is illustrated, hy way of example, in the accompanying drawings.

The illustrated staple comprises a length of stainless steel of chrome-cobal t-molybdertum alloy rod 10 having a circular cross-section and formed to a U-shape. This shape has two parallel arms 11 of equal length bridged at one pair of ends by a base 12 extending substantially perpendicularly to the arms. The free end portions of the arms 11 have their mutually facing surfaces tapered by planar chamfers 13 extending wholly across the widths of the arms to provide cutting edges 14 at the free ends.

IB The remaining feature of the Illustrated staple is the provision of a respective V-shaped notch IB in each arm. These notches are located in the mutually facing surfaces of the arms adjacent the free end portions and are inclined similarly to their respective chamfers 13 to provide barbs 16.

Use of the illustrated staple is indicated relative to two fragments 17 of a bone fractured at 18. The fragments are reduced to the desired positional relationship and then the staple is located as shown to bridge the fracture and driven into the bone with the staple arms penetrating respective fragments. As the free end portions of the staple arms enter 2B the bone, the chamfers are effective to force the fragments together at the fracture and so the staple secures the fragments in the desired relationship under compression. The compressive forces cause bone material to enter the notches 15, and the barbs 16 serve to inhibit undesired retraction of the staple from the bones.

While the invention has been described with more particular reference to the illustrated embodiment, which represents a preferred form of the invention for many specific applications in orthopaedic surgery, other forms may be used. For example, it may be advantageous for the base of the U-shape to be of non-symmetrical, inclined disposition relative to the arms or of stepped configuration, these different forms being suited to application to an inclined bone surface such as may arise in arthrodesis.

Claims (5)

1. An orthopaedic staple comprising an elongate member of biocompatible metal formed to a generally U-shape with parallel arms, the free end portions of said arms being tapered predominantly on their mutually facing surfaces, said arms being formed with retraction-resisting barbs by notches in said facing surfaces, and the staple being of sufficiently greater rigidity relative to bone to be substantially unyielding in shape when penentrated into bone to bridge a fracture, whereby such penetration exerts compressive force across said fracture to reduce the same by the action of said tapering, and bone material is urged into said notches by said force.

2. A staple according to Claim 1 wherein said arms are tapered only on their mutually facing surfaces.

3. A staple according to Claim 2 wherein said tapers extend wholly across each of said arms to provide cutting edges at the free end thereof.

4. A staple according to any preceding claim wherein the base of said U-shape is of hon-symmetrical inclined disposition relative to said arms, or is of stepped configurative to said arms.

5. A staple substantially as herein described with reference to the accompanying drawing.