As discussed previously in part one of this series, the approach to fracture management is different in wild birds compared to companion birds. The goal must always be to release the patient as soon as possible with as minimal stress as possible. Fractures can be managed conservatively or surgically. If a fracture cannot be repaired and the patient cannot be released, then careful consideration must be made into whether it is ethical to allow the patient to survive.
In some simpler fractures, basic confinement and cage rest may be all that is indicated. Conservative fracture management requires less time, costs less and can be utilised by veterinarians with less experience. If used correctly, conservative management can result in less stress for the patient, as well as eliminating the risk of post-surgical complications. It is important to note, however, that poorer outcomes have been associated with the use of external coaptation without surgical repair (Ponder and Redig, 2016).
For simple, non-displaced fractures of the coracoid, clavicle or scapula, birds weighing less than 1kg can be confined for 2.5 weeks in an enclosed area that they can move within but not flap their wings (Forbes, 2016). A retrospective study by Cracknell et al. (2018) showed that coracoid fractures managed in this way with no external coaptation resulted in a release rate of 75 percent of all birds and a 97 percent release rate of raptors alone. It is important to note that the Animal Welfare Act 2006 states that a bird must not be kept in an enclosure that does not allow for extension of the wings in all three dimensions; however, a short-term confinement is permitted when the bird is under the treatment of a veterinary surgeon.
If this is unacceptable, then in cases where minimal stabilisation of a thoracic limb fracture is required, the tips of the primaries can be taped together (Figure 1). This restricts the movement of the thoracic limbs without completely immobilising (Calvo Carrasco, 2019). A combination of cage rest and taping of the primaries can be useful in post-surgical cases, or in cases where the injured bone may already be stabilised, such as fractures where the ulna is fractured but the radius is intact (Forbes, 2016) or fractures of the minor metacarpal where the major metacarpal is intact.
External coaptation can be used for long-term management of fractures where the joints proximal and distal can be immobilised (Harasen, 2003). These techniques are never indicated for the humerus or femur. Figure-of-eight bandages are commonly used in practice to immobilise the distal wing (Figure 2), although several rules should be followed to ensure they do not cause iatrogenic trauma to the patient. Bandages should not be placed along the leading edge of the propatagium as pressure necrosis can occur (Forbes, 2016), which can be catastrophic for release. Figure-of-eight bandages should be changed approximately every three days to avoid contracture of the wing muscles and to identify any iatrogenic trauma that may have occurred from the bandage (Calvo Carrasco, 2019).
Aluminium foam-backed splints and Altmann’s tape splints can be used to immobilise the distal pelvic limb. Altmann’s tape splints are lightweight and useful in smaller birds weighing less than 300g to immobilise fractures of the tibiotarsus or tarsometatarsus (Ponder and Redig, 2016). A retrospective study by Wright et al. (2018) of birds weighing less than 200g with tibiotarsal fractures treated with tape splints resulted in a successful outcome in 97 percent of cases. In larger birds, aluminium foam-backed splints can be used to treat tibiotarsal fractures where surgery is not an option, as their malleable nature means they can be moulded to the shape required with ease (Calvo Carrasco, 2019). These splints can be secured in place using a cotton wool layer and a conforming bandage layer, ideally with external layers being changed every five to seven days to monitor for any iatrogenic damage from the bandage to the thin avian skin.
Fractures of the toes can be treated with a ball bandage, which keeps the digits in a semi-extended position (Calvo Carrasco, 2019). A ball of cotton wool is placed on the plantar aspect of the foot and the toes positioned around “grasping” the cotton wool. It is important to monitor the contralateral foot for any evidence of pododermatitis during the use of this technique.
Surgical fracture repair
In cases where conservative treatment is not feasible or appropriate then surgical repair can be performed. Fixation of long bone fractures is often carried out with hybrid type II external skeletal fixators (ESF). This technique utilises an intramedullary (IM) pin which exits the bone and is “tied in” to the ESF pins to stabilise the fracture in three dimensions (Figure 3). This technique is commonly used as the materials are lightweight, versatile and cost effective and it allows the patient to stand in a physiologically normal position (Calvo Carrasco, 2019). This technique is limited in that the IM pin needs to exit the long bone to allow it to attach to the ESF pins, and so cannot be used in bones where the joint space cannot be compromised, for example the tarsometatarsal joint of the pelvic limb. It has, however, been used with success in humeral, ulnar, metacarpal, femoral and tibiotarsal fractures and was associated with an 84 percent successful healing rate in wild raptors with tibiotarsal fractures (Bueno et al., 2015). Placing two ESF pins proximal and distal to the fracture has been reported to increase stiffness and safe load in torque and compression (Van Wettere et al., 2009), resulting in improved fracture reduction.
External skeletal fixators can also be used to varying degrees in avian long bones, as seen in Figures 4 and 5. Placement of the ESF pins depends on the location of the fracture, the length of the fractured bone and the pins available. IM pins can be used in some cases; however, these need to be chosen carefully as on their own they do not prevent rotational forces. They are often used in combination with an ESF, cerclage wire or external coaptation such as wing taping or figure-of-eight bandaging.
The use of bone plates is uncommon, due to their size compared to that of avian patients, the anatomy of avian bones, having generally thinner cortices compared to mammalian bones, and technical surgical skill required (Calvo Carrasco, 2019). Recent studies have shown that smaller plates can be used to successfully immobilise pectoral limb fractures in pigeons (Gull et al., 2012; Darrow et al., 2017); however, the use of bone plates is unlikely to be feasible when treating wild birds.
Amputation is not feasible for wild birds as it would prevent their release to the wild, which is always the main goal of treatment. In cases where fractures are catastrophic or fracture healing has failed, wild avian patients should be humanely euthanised.
A number of fixation methods are available for wild birds suffering from fractures. Fracture evaluation should occur in a similar method to that of our companion species and a fixation method chosen based on the fracture biomechanics as well as the technical skills of the veterinary surgeon. Any wild bird ready for release following fracture repair should be thoroughly flight tested for readiness to return to the wild to ensure optimum ability to survive.