TECHNIQUE

External Skeletal Fixation in Birds (Disease Investigation & Control - Treatment and Care)

Summary Information
Type of technique Health & Management / Disease Investigation & Control / Treatment & Care / Techniques:
Synonyms and Keywords External Fixators, Kirschner-Ehmer Splint, Biphase Splint
Description Detailed descriptions of the principles of external skeletal fixation and of the use of this procedure for fracture repair are given in general orthopaedic surgery texts. Further information on application to avian fractures are given by Bennett & Kuzma (J2.23.w2), Harcourt Brown (B11.16.w13) Simpson (B11.17.w14), Bennett (B12.42.w5), Martin and Ritchie (B13.42.w15), and Coles (B14); the following notes are intended as an indication of their potential use.

Type I fixator: (half-pin) Pins go through the skin, through the cortex on one side of the bone, and penetrate the cortex of the bone on the other side.

Type II fixator: (full-pin) Pins go through the skin, through both cortices of the bone and out through the skin on the other side. Stronger than type I.

Type III fixator: Type II in one direction plus type I perpendicular to this, with the external connecting bars connected to one another. Stronger than Type II

Type I modified biplanar fixator: Two sets of half-pins, placed at ninety degrees to one another , the external connecting bars being attached to one another by stabilising bars. Increased stabilisation for fractures in which a connecting bar cannot be placed on the medial aspect, e.g. humerus or femur.

Pins should be placed:

  • Avoiding open wounds
  • Avoiding nerves and major blood vessels
  • Avoiding large muscle bodies (to minimise loosening)
  • Avoiding tendons

N.B.

  • Strength is maximised if the collecting bar is as close as possible to the skin (but allowing for soft tissue swelling, and for cutting pins if necessary for removal).
  • At least two pins should be placed either side of the fracture - more are suggested as being preferred, e.g. three to four pins on either side.
  • Pins should be placed through stab-incisions of intact skin (not through open wounds).
  • Positive profile threaded pins provide a stronger bone-pin interface.
  • Pins should normally be placed with at least one pin on either side of the fracture at an angle to the bone (35-55% suggested) to decrease slippage: this is less important with positive profile threaded pins.
  • May be combined with an intramedullary polymer rod (e.g. formed from the plunger of a disposable hypodermic syringe)

Examples of use:

Type II fixator : tibio-tarsal, tarsometatarsal, ulnar, carpometacarpal fractures.

Type I fixator or type I modified biplanar fixator: humeral or femoral fracture.

An external fixator may also be used to stabilise a luxated elbow.

(J2.23.w2, B11.16.w13, B11.17.w14, B12.42.w5, B13.42.w15, B14)

Appropriate Use (?)
  • Treatment of some Impact Injuries, Crushing.
  • When recovery with a normal range of movement (full function) is desired.
  • Open fractures in which access for wound management is required.
  • Comminuted fractures.
  • Corrective osteotomies.

(B11.16.w13, B11.17.w14, B13.42.w15)

Notes
  • Provide good alignment and stability, thus promoting fast healing and minimal callus formation.
  • Properly applied, provide stabilisation against bending, shear and rotation forces.
  • Allow early return to function.
  • Allow free movement of adjacent joints.
  • Do not damage articular or periarticular structures.
  • Allows fracture stabilisation at the same time as soft tissue treatment for e.g. contaminated wounds.
  • Produce minimal intraoperative soft tissue damage.
  • Avoids the interference with the development of endostial callus which would occur if intramedullary pins were used. (J4.171.w14)
  • Lightweight.
  • Generally well tolerated by birds.
  • Simple to remove, often without anaesthesia (if bird is calm).
  • No permanent implants involved.
  • Strength is maximised if the collecting bar is as close as possible to the skin (but allowing for soft tissue swelling.
  • At least two pins should be placed either side of the fracture - more are suggested as being preferred, e.g. three to four pins on either side.
  • Pins should be placed through stab-incisions of intact skin (not through open wounds).
  • Positive profile threaded pins provide a stronger bone-pin interface.
  • Pins should normally be placed with at least one pin on either side of the fracture at an angle to the bone (35-55% suggested) to decrease slippage: this is less important with positive profile threaded pins.

(J2.23.w2, B11.16.w13, B11.17.w14, B12.42.w5, B13.42.w15, P7.1.w5)

Complications/ Limitations / Risk
  • Traditional systems with bars and clamps are relatively heavy and difficult to align.
  • Risk of iatrogenic fractures at the sites where the pins are inserted.
  • If methylmethacrylate is used to connect the bars, heat production during curing may cause burns: cooling e.g. with water may be required.
  • Methylmethacrylate takes a relatively long time to harden.
  • Pins may loosen prematurely (particularly with Type I fixators).
  • Potential risk of infection reaching bone via pins.

(J2.23.w2, B11.16.w13, B11.17.w14, B12.42.w5, B13.42.w15, B14, P7.1.w5)

Equipment / Chemicals required and Suppliers
  • Pins, e.g. Kirschner wires, Ellis pins, Steinmann pins.
  • Suitable means to insert pins, e.g. appropriate drill.
  • Connecting tubes (plastic tubing, Penrose drain, plastic syringe cases or syringe barrels, plastic slide transport cases).
  • Methylmethacrylate, Araldite, dental acrylic or similar material to fill tubes.

(J2.23.w2, B11.16.w13, B11.17.w14, B12.42.w5, B13.42.w15, B14, P3.8.w1, P7.1.w5)

Expertise level / Ease of Use Procedure should only be undertaken by an individual with appropriate clinical training and practical experience; this would usually be a veterinarian.
Cost/ Availability
  • Traditional systems with bars and clamps are relatively expensive.
  • Other equipment is generally cheap and readily available.
  • Cost of general anaesthetic and time of operators must also be considered.

(J2.23.w2, B12.42.w5, B13.42.w15)

Legal and Ethical Considerations In some countries there may be legislation restricting the use of this type of technique to licensed veterinarians. For example in the UK: "The Veterinary Surgeons Act 1966 (Section 19) provides, subject to a number of exceptions, that only registered members of the Royal College of Veterinary Surgeons may practice veterinary surgery."(see: LCofC1 - RCVS Guide to Professional Conduct 2000 - Treatment of Animals by Non-Veterinary Surgeons).).
Author Debra Bourne
Referee  
References J2.23.w2, B11.16.w13, B11.17.w14, B12.42.w5, B13.42.w15, B14, P3.8.w1, P7.1.w5

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