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Coracoid fractures in wild birds: a comparison of surgical repair versus conservative treatment.

Abstract: Medical records of wild bird admissions to the Australian Wildlife Health Centre at Healesville Sanctuary were analyzed for cases of unilateral coracoid fractures with known final outcomes. Forty-seven birds, comprising 13 species, fit these criteria. Of those birds, 18 were treated conservatively with analgesia and cage rest without coaptation bandaging, and 29 were treated with surgical correction of the fracture. Of the conservatively managed birds, 89% (16 of 18) were released back into the wild. Conversely, 34% (10 of 29) of the surgically managed birds were released. Treatment success for release differed significantly between treatment groups (P < .001). Intraoperative death from concurrent trauma was the major reason that surgically treated birds were not released. Given the high risks associated with surgical treatment and the high success rate of conservative management, cage rest without surgery appears prudent when managing coracoid injuries in birds.

Key words: trauma, coracoid, surgery, cage rest, rehabilitation, release, avian

Introduction

The thoracic girdle of birds comprises the coracoid and the scapula bones as well as the fused clavicles. (1,2) The coracoid bones act as supporting struts for the pectoral limbs by connecting them to the sternum. (2) This buttressing prevents collapse of the thoracic wall that would otherwise occur during contraction of the pectoral muscles during downward strokes of the wings. (1) Additionally, the coracoids help to suspend the sternum during gliding, which supports the viscera. (1)

Coracoid injuries commonly occur when birds crash into solid objects, such as walls, windows, or cars. (3,4) They are more likely to occur with frontal collisions when the wings are fanned. (4) Affected birds are unable to gain lift, and diagnosis is confirmed by palpation of the pectoral girdle and radiography. (5)

Much debate surrounds the management strategies for coracoid injuries in birds, with some authors advocating surgical correction (5-8) and others recommending conservative treatment. (9,10) This article describes the clinical outcomes of birds with coracoid injuries treated both conservatively and with surgical intervention.

Materials and Methods

The medical records of 2523 birds of common species admitted to the Australian Wildlife Health Centre (AWHC), Healesville Sanctuary, between January 2007 and June 2013 were examined. Inclusion criteria were birds with unilateral coracoid trauma and a known final outcome. Birds with evidence of other trauma were excluded from analysis. Birds were selected to treatment groups based on clinician preference for surgical or nonsurgical management. No consideration was given to species, weight, extent of injury, or clinical signs in selection for treatment group.

Birds were assessed for concurrent injuries by results of a combination of routine physical examination and test flying, examination under general anesthesia, and whole body radiographs. For birds treated conservatively for coracoid injuries, general anesthesia was induced by facemask with 5% isoflurane at the time of initial examination, and the injury was confirmed by radiography (Fig 1). An intravenous bolus of compound sodium lactate (2% of body weight; Baxter Healthcare Pty Ltd, Toongabbie, NSW, Australia) was then administered, and analgesia was provided with a combination of tramadol (5-30 mg/kg [dependent on species] IM; Tramal 100, CSL Biotherapies Pty Ltd, Parkville, VIC, Australia) and meloxicam (1 mg/kg IM). Analgesics with the same drug combination were continued for 3 days after presentation but given orally twice daily. Birds were confined to a small cage for 3 weeks with no bandaging or physiotherapy and fed species-specific diets. All birds in this treatment group were managed without regard to variables of patient size, wing loading ratio, or degree of fracture displacement. For surgical correction of coracoid injuries, initial triage was identical to that of the conservative treatment group. Birds were then stabilized for 2 days after presentation at which time surgery was performed by the methods described by Holz. (5) Postsurgical care was then identical to that of conservatively treated birds.

After 3 weeks of convalescence, each bird was anesthetized and radiographed to determine the extent of callus formation and to assess fracture stability (Fig 2). For surgically managed birds, the intramedullary pin was removed at this stage, provided adequate healing had occurred. Each bird in both treatment groups then entered a period of flight training and rehabilitation before release to the wild. Birds were considered fit for release if they could complete 10 laps of a 10-m wind tunnel with their respiratory rate returned to the resting rate within 30 seconds. (11)

Treatment outcomes were analyzed by the Fisher's exact test. The [alpha] level of statistical significance was set at P [less than or equal to] .05. Comparisons between species were not possible because of low individual numbers.

Results

Forty-seven birds satisfied these inclusion criteria. Species included in this study were laughing kookaburra (Dacelo novaeguineae; n = 11), rainbow lorikeet (Trichoglossus haematodus; n = 6), musk lorikeet (Glossopsitta concinna; n = 1), crimson rosella (Platycercus elegans; n = 9), eastern rosella (Platycercus eximius; n = 1), galah (Eolopirns roseicapilla; n = 3), yellow-tailed black cockatoo (Calyptorhynchus funereus; n = 1), Australian magpie (Cracticus tibicen\ n = 4), tawny frogmouth (Podargus strigoides, n = 7), southern boobook owl (Ninox novaeseelandiae; n = 1), Australian hobby (Falco longipennis; n = 1), peregrine falcon (Falco peregrinus; n = 1) and brown goshawk (Accipiter fasciatus; n = 1).

Of the 47 birds, 38% (18) were treated conservatively, whereas the remaining 62% (29) were treated surgically (Table 1). Of the birds treated conservatively, 89% (16 of 18) were released. The 2 birds (11%) that were not released died within 24 hours after presentation, despite triage. On postmortem examination, both birds had extensive free blood in the coelomic cavity and contusions to both lungs.

Of the birds treated surgically, 34% (10 of 29) were released, 14% (4 of 29) were not released because of an inability to fly appropriately, and 52% (15 of 29) died intraoperatively. Postmortem examinations of deceased birds revealed a range of soft tissue traumatic injuries that were the probable cause of intraoperative death. These soft tissue lesions were consistent with those of birds that had been treated conservatively and with those other birds admitted to the AWHC, but not included in this study, that died because of thoracic trauma. Therefore, these lesions were not considered a direct result of surgical intervention.

For all species examined, 3 weeks was adequate time for stable callous to form, and no birds required further cage rest. Birds treated conservatively were more likely to be released than were surgically treated birds (P < .001). The average duration of rehabilitation was 26 days ([+ or -] 4.6 days) for all birds, and there was no difference in duration of rehabilitation between treatment groups {P = .75). Duration of rehabilitation between species could not be compared because of low individual numbers.

Discussion

The surgical technique for repair of coracoid injuries in birds has been well described and is generally recommended for birds >300 g in body weight. (1,4,12) In smaller birds, coaptation with a figure-of-eight bandage to immobilize the wing to the body wall may result in adequate healing. (4,12) However, prolonged immobilization of wings in this manner may result in patagial contraction and a decrease in elbow function. (13) In this investigation, external coaptation was not applied to any patient. Absence of external coaptation did not increase fracture-healing time nor did it result in a loss of function or hinder return to the wild. This method of treatment, without coaptation, combined with 3 days of multimodal analgesia, resulted in rapid return to natural behavior in wild birds in this study, as evidenced by normal body posture and good appetite. Although some clinicians recommend bandaging and regular physiotherapy for coracoid injuries, in this author's experience, that method does not necessarily improve return to function for this type of injury. The large muscle mass surrounding the coracoid bones in avian patients likely provides enough stability to negate the need for external coaptation. The results of this study indicate that analgesia and cage rest without bandaging appear to be adequate methods of managing coracoid injuries in a variety of avian species. Future research should focus on the benefits of coaptation bandaging versus nonbandaging in management of coracoid injuries in birds.

Body size has been suggested (5) to be an inaccurate predictor of the success of conservative treatment for coracoid injuries in birds, whereas aspect ratio and wing loading have been suggested (5) as better indicators. The results of this investigation do not support the first part of this hypothesis because 4 of the species treated conservatively (yellow-tailed black cockatoo, Australian magpie, tawny frogmouth, and laughing kookaburra) had mean body weights >300 g. (14-16) Wing loading was not considered in managing any of the cases in this study, and many clinicians do not consider it important. (9)

Surgical correction of coracoid injuries can be difficult because patients are often further compromised by substantial soft tissue injuries, (3) which may increase the anesthetic risk. These traumatic injuries include large volumes of free blood in the coelomic cavity, punctures or tears to the heart, lung contusions, and free blood in the respiratory system (AWHC postmortem records). Other potential complications associated with surgical correction are advancing intramedullary pins into the coelomic cavity and penetrating important soft-tissue structures, damage to the shoulder joint resulting in periarticular fibrosis, shoulder joint ankylosis, and impaired shoulder function. (17) Although similar complications have been reported to occur in cases of coracoid injuries managed without surgery, these sequelae were not observed in any of the cases in this investigation.

In this investigation, the natural history of individual species was not taken into account for rehabilitation. Ideally, species-specific training regimes that accurately mimic wild flight patterns and encourage birds to develop natural behaviors, such as prey apprehension, should be used. However, given the myriad of species that are presented to the AWHC each year for rehabilitation, this was not practical. Therefore, a standard approach to rehabilitation, which has proven effective for 2 different avian species, was used." Further research, such as postrelease monitoring of rehabilitated birds, is required to ascertain whether such practices result in good survivorship for all species.

Given the propensity of coracoid injuries in birds to be accompanied by other traumatic injuries and the risks that those injuries pose to prolonged general anesthesia, recommending that coracoid injuries be managed conservatively would seem prudent. Standard principles of emergency medicine should be used for all birds that have acute traumatic injuries and should include fluid support, analgesia, antibiotic therapy when appropriate, and warmth. (18-20) If birds survive the first 48 hours after traumatic coracoid injury, the results of this investigation indicate that the prognosis for rehabilitation and release are excellent when birds are treated with cage rest and pain management alone, without coaptation bandaging or surgical intervention.

References

(1.) Orosz SE, Ensley PK, Haynes CJ. Avian Surgical Anatomy--Thoracic and Pelvic Limbs. Philadelphia, PA: WB Saunders; 1992.

(2.) King AS, McLelland J. Birds: Their Structure and Function. Eastbourne, UK: Bailliere Tindall; 1984.

(3.) Cousins RA, Battley PF, Gartrell BD, Powlesland RG. Impact injuries and probability of survival in a large semiurban endemic pigeon in New Zealand, Hemiphaga novaeseelandiae. J Wildl Dis. 2012; 48(3):567--574.

(4.) Martin H, Ritchie BW. Orthopedic surgical techniques. In: Ritchie BW, Harrison GJ. Harrison LR, eds. Avian Medicine: Principles and Application. Lake Worth, FL: Wingers Publishing Inc; 1994: 1137-1169.

(5.) Holz PH. Coracoid fractures in wild birds: repair and outcomes. Aust Vet J. 2003;81 (8):469--471.

(6.) Sanchez-Migallon D, Bubenik LJ, Lauer SK, et al. Repair of a coracoid luxation and a tibiotarsal fracture in a bald eagle (Haliaeetus leucocephalus). J Avian Med Surg. 2007;21 (3): 188-195.

(7.) Bennett RA, Kuzma AB. Fracture management in birds. J Zoo Wild! Med. 1992;23(1):5-38.

(8.) MacCoy DM. Treatment of fractures in avian species. Vet Clin North Am Small Anim Pract. 1992;22(1):225--238.

(9.) Redig PT, Francisco ON, Froembling M, Martinez LC. Coracoid fracture management in raptors: assessment of the conservative approach. Proc Annu Conf Assoc Avian Vet. 2009:351.

(10.) Orosz SE, Ponder JB. Cutting to the chase--part 1: wing fractures. Proc North Am Vet Conf. 2012: 1306-1308.

(11.) Mason PF. Indicators of Rehabilitative Success in Hospital Admissions of Kookaburras and Crimson Rosellas [master's thesis]. Parkville, Australia: University of Melbourne; 2006.

(12.) Orosz SE. Clinical considerations of the thoracic limb. Vet Clin North Am Exot Anim Pract. 2002; 5(1):31--48.

(13.) Redig PT. The use of an external skeletal fixatorintramedullary pie tie-in (ESF-IM fixator) for treatment of longbone fractures in raptors. In: Lumeij JT, Remple JD, Redig PT, et al, eds. Raptor Biomedicine III Including Bibliography of Diseases of Birds of Prey. Lake Worth, FL: Zoological Education Network; 2000:239-253.

(14.) Marchant S, Higgins PJ. Raptors to lapwings. In: Marchant S, Higgins PJ, ed. Handbook of Australian, New Zealand and Antarctic Birds. Vol 2. South Melbourne, Australia: Oxford University Press; 2007:21-320.

(15.) Higgins PJ. Parrots to dollarbird. In: Higgins PJ, Peter JM, Cowling SJ, eds. Handbook of Australian, New Zealand and Antarctic Birds. Vol 4. South Melbourne, Australia: Oxford University Press; 2006:25-646.

(16.) Higgins PJ, Peter JM, Cowling SJ. Boatbills to starlings. In: Higgins PJ, Peter JM, Cowling SJ, eds. Handbook of Australian, New Zealand and Antarctic Birds. Vol 7. South Melbourne, Australia: Oxford University Press; 2006:396-772.

(17.) Bennett RA. Orthopedic surgery. In: Altman RB, Clubb SL, Dorrestein GM, Quesenberry K, eds. Avian Medicine and Surgery. Philadelphia, PA: WB Saunders; 1997:733-767.

(18.) Bowles H, Lichtenberger M, Lennox A. Emergency and critical care of pet birds. Vet Clin North Am Exot Anim Pract. 2007;10(3):345-394.

(19.) Graham J, Heatley JJ. Emergency care of raptors. Vet Clin North Am Exot Anim Pract. 2007;10(2): 395-418.

(20.) de Matos R, Morrisey JK. Emergency and critical care of small psittacines and passerines. Semin Avian Exot Pet Med. 2005; 14(2):90-105.

T. Franciscus Scheelings, BVSc, MVSc, MANZCVSc (Med Aust Wildl), Dipl ECZM

From the Australian Wildlife Health Centre, Healesville Sanctuary, Healesville, VIC 3777, Australia.

Table 1. Outcomes of wild birds with coracoid injuries treated at the
Australian Wildlife Health Centre (Healesville, VIC, Australia) from
2006-2013.

                             Conservative              Surgical
                            treatment. No.           treatment. No.

Species                  Released       Not      Released       Not
                                     released                released

Australian hobby             1          --          --          --
Australian magpie            2          --           1           1
Brown goshawk               --          --           1          --
Crimson rosella              3           2          --           4
Eastern rosella              1          --          --          --
Galah                       --          --           1           2
Laughing kookaburra          2          --           5           4
Musk lorikeet                i          --          --          --
Peregrine falcon            --          --           1          --
Rainbow lorikeet             2          --          --           4
Southern boobook owl        --          --          --           1
Tawny frogmouth              3          --           1           3
Yellow-tailed black          1          --
  cockatoo
Total (%)                16 (89%)     2 (11%)    10 (34%)    19 (66%)
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Article Details
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Author:Scheelings, T. Franciscus
Publication:Journal of Avian Medicine and Surgery
Article Type:Report
Geographic Code:8AUST
Date:Dec 1, 2014
Words:2398
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