Association of Avian Veterinarians

Alternative IM PinsAuthor(s): James GainesSource: AAV Today, Vol. 2, No. 2 (Summer, 1988), p. 101Published by: Association of Avian VeterinariansStable URL: http://www.jstor.org/stable/30134429 .

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Orthopedic Suggestions The primary considerations in avian

orthopedic surgery for prevention of nonunions and/or large callous for- mation at the fracture site are maintenance of bone apposition and prevention of rotation. During nor- mal healing, the bone first resorbs at the interface before new bone is laid down. K-E devices hold the bone ends apart once this resorption has taken place, so you lose the apposi- tion. Because of this, I have no con- fidence at all with K-E devices in birds, especially in the humerus. Besides, they are heavy, the birds don't like them, and the pins tend to wiggle.

The humerus is unique in avian applications because we have a situa- tion of a very "puny" bone in the avian brachium supporting a very heavy limb, and, unlike the legs, where the force is supported by the floor or perch, gravity provides a powerful distracting force. In addi- tion, the carrying angle of the elbow lends itself to torsional disturbances and accidents.

Along with a small intramedullary pin, we apply tiny pins at oblique angles, one distal and one proximal to the fracture. Each pin has a hook on the end to hold a rubber band which traverses the hooks. Because of the constant impacting of the rubber band, the oblique pins are driven deeper and the bone ends are kept in apposition. The rubber bands should be checked every 3-4 days; if they are too tight, necrosis of the ends may Occur.

If either the radius or the ulna is broken with substance loss, a normal intramedullary pin also holds the op- posing ends apart. Although the bone may heal over time, callous for- mation produces swelling which may impair nerve, tendon and vessel func- tion. An osteotomy can be made on the opposite bone to shorten it slightly, and the rubber band techni- que employed for better healing.

Similarly, with a gunblast injury, where a section of the ulna must be removed, one can remove a piece of radius on a vascular pedicle, trim it with a bone burr and telescope it in-

to the ulna for bone to bone align- ment of the ulna. Thus, one transfers a piece of the radius into the ulna to substitute for ulnar substance loss.

Another major problem in avian orthopedic surgery is the common use of pins (both metal and plastic) that are too large. It is very difficult to maintain the integrity of the bone if the trabeculae of the medullary canal has been totally destroyed by a tight- fitting pin. Because the trabeculae of bones provide the intrastructure that gives bones great strength at low weight (by maintaining the distance between cortices), significant damage

Rhonda Sayle (left) assists Michelle Curtis, DVM in a lab to develop avian microsurgical skills.

to this network from pin insertion weakens the bone in areas other than the fracture site itself. When a bone fails, it doesn't burst; it implodes or collapses inward on the concave side of the flexion deformity. Although the bird may "apparently" heal and fly away, sometime later in life, he may go into a strenuous maneuver and experience a spontaneous in- flight bone failure.

A very small pin can be delicately woven through the trabeculae. As lit- tle as 1/4 filling of the medullary canal is sufficient for the femur and aerated bones. With the assistance of a mini-pin driver, the surgeon can place the pin just barely through the cortex. As soon as the pin can be pushed on through the cortex by hand, one stops using the mini-pin driver to prevent loosening the pin more than necessary. The pin is then retrograded into the other cortex.

In humeral and ulnar fractures, whenever possible, work from the volar or ventral surface of the wing.

If you interfere with the suspensory ligaments of the feathers dorsally, you've wasted your time because the bird won't fly well. - l-James Doyle, M.D., Arlington, Texas

Alternative IM Pins We use 20 gauge spinal needles

from human hospitals as in- tramedullary pins in birds. They are sharp-pointed, non-reactive, lightweight, hollow, and inexpensive. Because they are flexible, they can be maneuvered around. We may use 2 or 3 in a single fracture repair. - James Gaines, DVM, Chantilly, Virginia

Orthopedic Technique to Avoid Joint Involvement

In order to avoid penetration of a joint and prolonged joint immobiliza- tion for repair of an oblique midshaft tibiotarsal fracture in a goose, a 1/16" pin was advanced proximally through the lateral cortex into the medullary space of the distal tibiotar- sal fragment at about a 300 angle. The pin was flexible enough to deflect off of the medial cortex and was passed into the proximal tibiotar- sal fragment after open reduction. The leg was placed in a schroeder- Thomas splint for one week and the intramedullary pin was removed in four weeks. The goose had no lameness after pin removal. In retrospect, leaving the schroeder- Thomas splint on for two weeks may have prevented some bending of the intramedullary pin, which did occur. - Bruce Lund, DVM and Norma

Ceccardi, AHT, Grass Valley, California

Use of Physical Therapy (From The Wildhlfe Center of Virginia Progress Report, Fall, 1987)

A major problem associated with the treatment of avian fracture repair is a stiffening of the immobilized joints and muscles. The more severe fractures requiring surgical treatment

VOL.2 NO.2 1988 101

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