Ex Vivo Biomechanical Comparison of Titanium Locking Plate, Stainless Steel Nonlocking Plate, and Tie-in External Fixator Applied by a Dorsal Approach on Ostectomized Humeri of Pigeons (Columba livia).

To compare the bending strength of a locking plate (LP), nonlocking plate (NLP), and an external skeletal fixator intramedullary pin (ESF-IM) tie-in fixation applied by a dorsal approach in an avian humerus fracture model, 5 left humeri obtained from pigeon (Columba livia) cadavers were randomly assigned to each repair technique (n = 15). The ESF-IM group was repaired with a 0.062-inch intramedullary pin tied-in with two 0.035-inch positive profile transfixation pins using acrylic filled plastic tubing. The LP group was repaired with a dorsally applied titanium 1.6-mm screw 7-hole locking plate (1 bicortical and 2 monocortical screws in each segment). The NLP group was repaired with a dorsally applied 6-hole stainless steel 1.5-mm dynamic compression plate (all bicortical screws). All constructs were applied before complete ostectomy to allow perfect reconstruction. Constructs were cyclically tested nondestructively for 1000 cycles in four-point bending before being tested to failure. Outcome measures included stiffness, strength, and strain energy. All specimens cycled without failure. The ESF-IM specimens were significantly stiffer and stronger than the plated repair groups. Plated constructs had significantly higher strain energies than ESF-IM. LP and NLP were of equal stiffness, strength, and strain energies. This study demonstrated that bending biomechanical properties of the ESF-IM configuration were superior to those of the dorsal plate fixation. Exact properties of fixation required to facilitate avian fracture healing are largely unknown. Further study, including assessments of optimal plate position and configuration, and torsional and in vivo studies in avian species are warranted.

Histologic Evaluation of Critical Size Defect Healing With Natural and Synthetic Bone Grafts in the Pigeon ( Columba livia ) Ulna.

Fracture and bone segment loss are major clinical problems in birds. Achieving bone formation and clinical union in a fracture case is important for the survival of the bird. To evaluate the efficacy of bone grafts for defect healing in birds, 2 different bone grafts were investigated in the healing of a bone defect in 24 healthy pigeons ( Columba livia ). In each bird, a 1-cm critical size defect (CSD) was created in the left ulna, and the fracture was stabilized with external skeletal fixation (ESF). A graft of hydroxyapatite (HA) alone (n = 12 birds) or demineralized bone matrix (DBM) combined with HA (n = 12 birds) was implanted in the CSD. The CSD healing was evaluated at 3 endpoints: 3, 6, and 12 weeks after surgery. Four birds were euthanatized at each endpoint from each treatment group, and bone graft healing in the ulna CSD was evaluated by histologic examination. The CSD and graft implants were evaluated for quality of union, cortex development, and bone graft incorporation. Results showed no graft rejection in any bird, and all birds had connective tissue formation in the defect because of the bone graft application. These results suggest that bone defect healing can be achieved by a combination of osteoinductive and osteoconductive bone graft materials for clinical union and new bone regeneration in birds. The combination of DBM and HA resulted in a better quality bone graft (P < .05) than did HA alone, but there was no significant differences in cortex development or bone graft incorporation at 3, 6, or 12 weeks. From the results of this study, we conclude that HA bone grafts, alone or in combination with DBM, with external skeletal fixation is suitable and safe for bone defect and fracture treatment in pigeons.

Evaluation of three miniplate systems for fracture stabilization in pigeons (Columba livia).

Bone plates are rarely used in avian fracture management for several reasons, and until recently, there was no plating system considered appropriate for use in birds with a body mass less than 500 g. To evaluate 3 different miniplate systems in avian fracture repair, 3 groups (A, B, and C) of 6 pigeons (Columba livia) each were used. The left ulna and radius of the pigeons were transected, and the ulna was stabilized. In group A, a 1.3-mm adaption plate was used. In group B, a limited contact system was created with washers that were placed between a 1.3-mm adaption plate and the bone. The intention was to reduce the compression of the periosteum and vascular damage to the bone. In group C, a 1.0-mm maxillofacial miniplate was used. Healing was evaluated with radiographs after 14 and 28 days. A flight test was conducted on day 28; the birds were then euthanatized, and the wing was dissected. Birds in group A with the adaptation plate achieved the best flight results (100%). In group B birds, no effect of the limited contact concept was visible at necropsy, and a high percentage of the screws had loosened, leading to failure (33%). The maxillofacial miniplates of group C birds were too weak and bent (100%). These results indicate that the adaption plate 1.3 met the desired requirements. To improve the system, further trials, with smaller drill bits and with screws having a smaller thread pitch, are recommended.

Ultrasound therapy for the prevention and correction of contractures and bone mineral loss associated with wing bandaging in the domestic pigeon (Columba livia).

Figure-of-eight wing bandaging is widely used to treat wing injuries, to immobilize wings before and after fracture repair, and during transient wing paralysis. However, prolonged bandaging can lead to bone loss and to contractures and reduced range of joint motion. Studies evaluating the efficacy of therapeutic ultrasound to reverse and prevent bandaging-associated contractures in pigeons (Columba livia) showed a significant increase in elbow and carpal extension after 10 twice weekly ultrasound treatments when started either 4 or 11 days after bandage placement. In addition, after 42 days of wing bandaging, three ultrasound treatments stimulated a faster reversal of carpal wing rotation loss than removal of the bandage over the 10-day treatment period. Finally, bone loss in response to 28 days of bandaging was significant, progressed at 2.8% per week, and was not affected by ultrasound treatment twice weekly during this period. Therefore, therapeutic ultrasound prevented and reversed loss of wing extension associated with figure-of-eight bandaging but did not lessen the disuse osteoporosis created by bandaging in these birds.

Impact injuries and probability of survival in a large semiurban endemic pigeon in New Zealand, Hemiphaga novaeseelandiae.

The New Zealand Pigeon or kereru (Hemiphaga novaeseelandiae) frequently collides with windows and vehicles. In this study of 146 kereru collected from 1996 to 2009, we used 118 radiographs and 91 necropsies to determine skeletal and soft tissue injuries. Vehicle collisions resulted in more damage to the extremities (wing and femur), whereas collisions with windows resulted in trauma to the head, fractures/dislocations of the coracoids and clavicles, and ruptured internal organs. Soft tissue injuries included damage to the flight muscles and heart ruptures caused by fractured coracoid bones, as well as extensive bruising of pectoral muscles and hemorrhaging of the lungs. Rehabilitation time was not related to number of skeletal injuries sustained, nor was the time until death for those that did not survive. In general, kereru with greater numbers of injuries were less likely to survive rehabilitation. Flight speed and force calculations suggest that a 570-g kereru would collide with 3-70 times the force of smaller birds (5-180 g); this may explain the discrepancies between the injuries characterized here and those reported for North American passerines. The differences in injuries sustained from collisions with windows and cars can be used to inform rehabilitators about the possible nature of injuries if the source of impact is known.

[The use of collagen fasciae and fibrin adhesive for supporting wound healing in skin defects with large surfaces]. / Einsatz von Kollagenfaszien und Fibrinkleber zur Unterstützung der Wundheilung bei grossflächigen Hautdefekten.

In 50 domestic pigeons, two circular pieces were removed from the skin to the right and left of the crista sterni, and the wounds were treated in different ways: A. with a collagen membrane dampened with a sodium chloride solution, B. with a fibrin glue, C. with a combination of A) and B). The wounds of group D were left untreated. Scab formation could be seen in all cases, also under the transparent membrane. The collagen membrane had no protective function in the experiment, however, it contributed to the acceleration of re-epithelialisation and the reduction of the wound diameter. The additional application of fibrin glue improved wound healing even further.

Fracture healing after stabilization with intramedullary xenograft cortical bone pins: a study in pigeons.

OBJECTIVE: To investigate the effectiveness of intramedullary xenograft cortical bone pins compared with stainless steel Kirschner wire for the repair of a standardized avian humeral fracture. STUDY DESIGN: Prospective randomized study. SAMPLE POPULATION: Thirty mature pigeons (Columba livia). METHODS: Birds were randomly assigned to 3 groups. Transverse mid-diaphyseal humeral fractures were created in 1 humerus in each bird. Fractures were stabilized with intramedullary ostrich or canine xenograft cortical bone pins or Kirschner wire. Radiographic, histological, and biomechanical assessments were used to compare fracture healing 6 weeks after fracture stabilization. The contralateral humerus of each bird was used as a control. RESULTS: All fractures healed regardless of intramedullary pin type. There were no statistically significant biomechanical differences among groups or within groups. Xenograft cortical bone pins induced a mononuclear inflammatory reaction that did not impair bone healing. Bones stabilized with intramedullary cortical bone pins had more periosteal callus and inflammation at the fracture site than bones stabilized with stainless steel Kirschner wires. CONCLUSIONS: Intramedullary xenograft cortical bone pins, derived from mammalian or avian sources, appear to represent an alternative for the repair of avian humeral fractures. CLINICAL RELEVANCE: Intramedullary xenograft cortical bone pins are biodegradable and may reduce the need for additional surgery to remove implants after fracture healing.