Holding power of different pin designs and pin insertion methods in avian cortical bone.
OBJECTIVE
To measure pullout strength of four pin types in avian humeri and tibiotarsi bones and to compare slow-speed power and hand insertion methods.


METHODS
Axial pin extraction was measured in vitro in avian bones.


METHODS
Four cadaver red-tailed hawks and 12 live red-tailed hawks.


METHODS
The pullout strength of four fixator pin designs was measured: smooth, negative profile threaded pins engaging one or two cortices and positive profile threaded pins. Part 1: Pins were placed in humeri and tibiotarsi after soft tissue removal. Part 2: Pins were placed in tibiotarsi in anesthetized hawks using slow-speed power or hand insertion.


RESULTS
All threaded pins, regardless of pin design, had greater pullout strength than smooth pins in all parts of the study (P < .0001). The cortices of tibiotarsi were thicker than the cortices of humeri (P < .0001). There were few differences in pin pullout strengths between threaded pin types within or between bone groups. There were no differences between the pullout strength of pins placed by slow-speed power or by hand.


CONCLUSIONS
There is little advantage of one threaded pin type over another in avian humeri and tibiotarsi using currently available pin designs. There were few differences in pin pullout strengths between humeri and tibiotarsi bones. It is possible that the case of hand insertion in thin cortices minimizes the potential for wobbling and therefore minimizes the difference between slow-speed drill and hand insertion methods.


CONCLUSIONS
Threaded pins have superior bone holding strength in avian cortices and may be beneficial for use with external fixation devices in birds.
Degernes
L A
LA
Department of Companion Animals and Special Species Medicine, College of Veterinary Medicine, NCSU, Raleigh 27606, USA.
Roe
S C
SC
Abrams
C F
CF
D000818:Animals; D000835:Animals, Wild; D001696:Biomechanical Phenomena; D001717:Birds / Q000293:injuries / Q000502:physiology / Q000601:surgery*; D001858:Bone Nails / Q000592:standards / Q000662:veterinary*; D016267:External Fixators / Q000662:veterinary; D005592:Fracture Fixation / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D006811:Humerus / Q000293:injuries / Q000502:physiology / Q000601:surgery; D013314:Stress, Mechanical; D013639:Tarsal Bones / Q000293:injuries / Q000502:physiology / Q000601:surgery; D013977:Tibia / Q000293:injuries / Q000502:physiology / Q000601:surgery