Traumatic fractures in birds are common and frequently occur in the mid to distal third of the humerus.1 Fracture repair in birds has historically relied on external fixation or external coaptation; although subjective assessments have indicated good outcomes, the devices can limit function and require daily care and a second anesthetic episode for removal. There is a paucity of information available on avian bone plating, and it is suggested the practice is not common because of the unique morphological shape of avian bones, thin cortices, the necessity to allow flight, and the cost and technical difficulties associated with use of plating equipment.1,2 With technological advancements for plating techniques, many of these hurdles may be overcome. Plates currently are available in sizes appropriate for smaller species, can be conformed to bones in multiple dimensions, and can have locking screws, which may be beneficial in bones with thin cortices. Also, plates can allow early return to function and may not require removal after healing.
Successful plate fixation has been described in a few reports. For example, plates were applied relatively easily and rapidly to the ulna of pigeons (Columba livia).2 In that study,2 a dorsally placed 1.3-mm, stainless steel 11-hole adaption plate designed for human phalanges was placed on the ulnas and resulted in good flight ability at 28 days in all of the birds.
Biomechanical testing is frequently performed on bones of humans and small mammals and provides valuable information about the use of a given construct before placement in vivo. Previous biomechanical testing of avian bones has been limited to 1 study3 in which the investigators focused on optimization of a single external fixation technique in raptors. Avian species may provide a unique opportunity for evaluating the application of new locking plates because of the reduced cortical mass and dimension of their bones. Biomechanical evaluation of avian bones may form the basis for use of these systems in avian species or, potentially, in other small bones with reduced cortical dimensions.
The specific objectives of the study reported here were to evaluate the stiffness, strength, and strain energy of intact avian humeri and humeri with a 1-mm ostectomy gap stabilized by use of a titanium locking plate construct or stainless steel nonlocking plate construct. We hypothesized that the intact humeri would possess the highest strength and stiffness in both bending and torsion and that no significant biomechanical differences would exist between the repaired ostectomized humeri.
Supported by the Companion Animal Fund at the University of Tennessee College of Veterinary Medicine and by Kyon AG.
The authors thank Sun Xiaocun for statistical assistance and Misty Bailey for technical assistance.
Dynamic compression plate
Mini (3.5/4) advanced locking plate system (ALPS), Kyon AG, Zurich, Switzerland.
DCP, Veterinary Orthopedic Implants, St Augustine, Fla.
Smooth-On 300Q, Smooth-On Inc, Macungie, Pa.
Instron ElectroPuls E1000, Illinois Tool Works Inc, Norwood, Mass.
MTS 858, MTS Systems Corp, Eden Prairie, Minn.
Valspar Micromist spray (Flat), The Valspar Corp, Wheeling, Ill.
SAS for Windows, version 9.4, SAS Institute Inc, Cary, NC.
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