Authors of section

Author

Cassio Ferrigno

Executive Editor

Amy Kapatkin

General Editor

Noel Moens

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External fixator

1. Principles

General considerations on the external fixator can be found here.

In the tibia, the type 1 fixator should be placed medially. Type 1 a, 1b, 2 and 3 frames can be used in the tibia.

Illustrations of fracture types

A) Comminuted, unreduced fracture
B) Comminuted fracture aligned biologically
C) Fracture aligned and biologically stabilized

plate and rod

2. Preparation and approach

This procedure is performed with the patient in dorsal recumbency.

external fixator

The fixator pins must be placed in the center of the bone. Two hypodermic needles or palpation can be used to locate the bone during closed application of the fixator.

external fixator

A stab incision is performed at the desired location of pin placement. It is preferred to incise between muscles mass.

external fixator

3. Pin placement and insertion

Pin selection

The pin diameter should be 20-25% of the bone diameter. Positive profile pins should be used.

external fixator

Predrilling

Pre-drilling the hole is strongly recommended prior to pin insertion. The diameter of the drill bit should be 1mm smaller than the pin diameter.

external fixator

Pin insertion

A drill is used to insert the pin. Only slow rpm speeds (<150 rpm) should be used to avoid bone necrosis.
external fixator

The illustration shows the appropriate pin placement centered in the bone.

external fixator

The illustration shows the appropriate pin placement centered in the bone protruding 2mm through the trans cortices.

external fixator

Safe corridors for the tibia

In the illustration, the green, yellow and red zone show the low, mild, and high morbidity respectively.

external fixator

Note: In the proximal tibia the cross section remains a triangular shape. Therefore, placing the pins caudally is preferable for better bone purchase.

external fixator

4. Placement of clamps and connecting rods

The first pins inserted are the ones furthest from the fracture.

external fixator

The frame is used to align the fracture. Alternatively a distractor device can be used for this purpose.

approaches for minimally invasive osteosynthesis mio

The remaining pins are inserted.

Note: One pin in each segment needs to be placed near the fracture line.

external fixator

Note: The clamps and connecting bars should be approximately 1cm away from the skin. The soft tissues will swell and be in contact with the fixator if placed any closer.

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5. Case example

3 month old mix breed dog with a 42-A1 fracture.

external fixator

The fracture was repaired with a type 1b external fixator.

external fixator

Postoperative radiographs at 20 days.

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Postoperative radiographs at 20 days (implant removal).

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6. Aftercare

Phase 1: 1-3 day after surgery

The aim is to reduce the edema, inflammation and pain. Integrative medical therapies, anti-inflammatory and analgesics medications are indicated.

In order to avoid the contact between the skin and the connecting bars, sterile sponges should be placed in between.

The pin-skin interface should be cleaned and adequately protected.

In most cases, 10-20 minutes of ice therapy is recommended every 8 hours.

Phase 2: 4-10 days after surgery

The aim is to resolve the hematoma, the edema and control the pain, as well as to prevent muscle contracture. Anti-inflammatory and analgesic medications may still be needed. Rehabilitation and integrative medical therapies can be used.

If the dog is not starting to use the limb within few days after surgery, a careful evaluation is recommended.

10-14 days after surgery the sutures are removed.

Phase 3: 10 day-bone healing

Radiographic assessment is performed every 4-8 weeks until bone healing is confirmed.

Patients with external fixators should be checked every 7-10 days. The pin track infection and fixator stability should be assessed.

Disassembly or staged disassembly

When there is evidence of good callus formation, staged disassembly of the construct can be considered.

Complete removal of ESF is indicated once the fracture is healed.