Authors of section

Author

Anton Fürst

Executive Editor

Jörg Auer

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Plate fixation

1. Principles

Anatomical reduction of the outer part of the orbit is crucial for correct function of the eye.

plate fixation

It is important to palpate the inner surface of the orbit to identify and remove any bone fragments that can damage the eye.

plate fixation

2. Preparation and approach

This procedure is performed with the patient placed in lateral recumbency through the approach to the orbit.

approach to the orbit

3. Reduction

After wound debridement has been achieved and the trauma assessed, the fracture is reduced.
The outer parts of the orbit (frontal, temporal and zygomatic bones) are typically displaced inwardly. They must be reduced to their normal position cautiously using one of several methods.
Periosteal elevators or Langenbeck retractors can be effectively applied for fracture reduction.

plate fixation

In addition, a specially designed reduction instrument, manufactured in two sizes (2.4 mm and 3.5 mm), has recently become available. It consists of a horizontal cross handle, connected to a tap-like rod that is twisted into the bone fragment.

Of all the various instruments that are available, these are best suited for the use in horses. Depending on the size of the fragment a 1.8 or 2.4 mm drill hole is prepared and the instrument inserted into the bone fragment.

plate fixation

Occasionally it is necessary to trim the bone fragments to facilitate correct anatomic repositioning and fracture reduction.

plate fixation

4. Fixation

Plate selection and preparation

2.7-mm or 3.5-mm reconstruction plates are suitable for fixation because they are easily adapted to the shape of the bones.
If several bones are fractured, a long (12-16 holes) plate becomes necessary.

The plate needs to be bent and twisted to fit the shape of the bone with the help of a template.

plate fixation

Screw length

Screws of only 8-10 mm length should be used to avoid damage to the eye.

plate fixation

The plate needs to be positioned so that each fragment is fixed with at least two screws.
Not every plate hole needs to be filled with screws.

Note: Remember to protect the nerves which run close to the fracture.

plate fixation

Different types of plates were used in this case.

plate fixation

5. Closure

The skin incision is closed routinely.

plate fixation

6. Reduction of the inner orbital fracture

If the globe is displaced into the maxillary sinus, reduction needs to be performed after the outer orbital fracture has been stabilized.

After the skin over the maxillary bone has been incised, an osteotomy of that bone has to be made to gain access to the inner part of the orbit. This bone flap has a size of 3-4 cm and allows introduction of at least 2 fingers.

plate fixation

The inner part of the orbit is carefully reduced into normal position by digital pressure.

facial skull orbital region

7. Closure

The sinus is flushed and the blood removed. The flap is brought back into normal position and the skin is closed.

8. Aftercare

A head bandage and padded head protection are applied to the patient during recovery from anesthesia.

The horse is maintained in stall rest for about two weeks followed by small paddock exercises for another two weeks.

Depending on the healing progress, nonsteroidal anti-inflammatory drugs and antibiotics are given for 3 to 5 days, or longer if required.

In most cases implants do not need to be removed provided that wound healing is normal and no persistent draining tracts develop.