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Wing Injuries

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Wing Injuries Wing Injuries Kimberly A McMunn MS MPH DVM – Anatomy Review – Radiological Positioning – Patient Evaluation – Approaches to Fracture Management – Physical Therapy – Monitoring Healing – Complications – Treatments for Specific Injuries Anatomy of the Wing Proctor and Lynch 1993 Wing Musculature- Ventral Proctor and Lynch 1993 Wing Musculature- Dorsal Proctor and Lynch 1993 Wing Musculature- Flight Proctor and Lynch 1993 Flight bones Scott 2016 Wing Vasculature Proctor and Lynch 1993 Bird bones vs mammal bones – Bone cortices thin and brittle but very strong, with high calcium content – Any defect in wall greatly reduces their strength – Less holding power (compared to mammals) for fixation hardware – Limited soft tissue over many long bones, very thin skin, bone fragments exteriorize easily Bird bones vs mammal bones – Pneumatic bones- humerus, and ulna in some species (Pelicans and CA condors) – Majority of callus tissue in healing is derived from the periosteal surface, and blood supply to the periosteum from surrounding soft tissues is very important. The IM circulation appears to be of less significance in avian bone healing than in mammals Radiographic Positioning 2 Orthogonal Views!! Scott 2016 Evaluation of the Patient – Evaluate signalment, history, and physical and orthopedic exams – Hands-off observation for mentation, posture, respiration and general appearance – Consider anesthesia or sedation for exam – Consider co-morbidities, including eye, head or intracoelomic trauma in wild birds, or malnutrition and associated poor bone condition in companion birds Differential Dx for Wing Droop/Fractures – Infectious: Bacterial, Fungal (Aspergillosis) – Metabolic: Gout – Nutritional: Ca deficiency, Ca/P imbalance, Vit D deficiency, excess protein – Toxicosis: Lead, Zinc – Physical: TRAUMA, brachial plexus avulsion – Neoplastic Clinical signs of fractures – Wing droop – Local swelling – Apparent loss of limb function – Localized pain – Altered limb positioning – Inability to elevate wing above the horizontal plane (key clinical finding in coracoid fractures) Factors contributing to Fractures – Poor bone integrity, especially in captive birds- malnutrition (inadequate calcium), lack of exercise (loss of bone mass), lack of vitamin D – Reproduction in female birds- calcium deficit – Underlying bone disease- neoplasia, osteomyelitis Basic Orthopedic Principles – Establish early and complete rigidity – Maintain normal longitudinal and axial alignment, as well as bone length – Promote load-sharing with the bone when possible – Return the limb to normal function and ROM ASAP – Reduce morbidity – Promote patient mobility and comfort Approaches to Fracture Management – Confinement/Cage Rest – External Coaptation – Surgical Fixation – Instances occur where all three are used simultaneously or successively – Regardless of method, Fx require active management to ensure optimal outcome Prognosis and choosing best approach – Goal of repair (flight?) – Simple vs comminuted – Site of fracture – Open vs closed, infection – Size of the bird – Comorbidities – Acute vs chronic – Age of the bird Prognosis – Companion and aviary birds rarely require full mobility, generally excellent prognosis – Wild birds must have near perfect wing function to survive in the wild. Any slight rotation in the distal wing can alter flight. If synostosis occurs, the bird may not be able to fly. – Suggestions that pneumatic bones heal slower than medullary bones – Clinical stability may precede radiographic evidence that the bone is healed Prognosis – Open fractures- exposed bone readily separates from blood supply, high risk of bone infection, poorer prognosis- if there is ANY skin wound present, assume open – High-energy forces are more likely to shatter a bone, resulting in comminuted fracture, often with significant soft tissue damage, fractured bone cannot contribute to load-sharing, poorer prognosis – Low-energy forces (collision with stationary object) often results in simple transverse or oblique fracture, often easier to repair, with better prognosis – Proximity to a joint- if flight is required, fractures involving elbow or carpus have poor prognosis Amputation – Federally protected species- cannot amputate above elbow – Companion birds- may be an option – Ability of bird to adapt depends on their size, demeanor and required return to function – Amputation through bone is preferred to disarticulation, the bone end will atrophy and maintain adequate soft tissue coverage – Parrots do learn to adapt to wing amputation at the proximal 1/3 of humerus Approaches to Fracture Management Ponder and Redig 2016 Cage Rest – Suitable in a very small number of situations – Very small birds – Injuries not amenable to bandaging or surgery Coaptation – Requires less skill/experience than surgical fixation – Most common for initial or temporary immobilization – Preferred method for shoulder girdle fractures and metacarpal fractures Coaptation may be considered if – Full return to function is not required – Fx are pathologic as a result of metabolic bone diseases – Bones are too soft to hold hardware – The patient is too small for internal fixation alternatives – The surgical or anesthetic risk is judged to be too great Coaptation- warnings – Monitor carefully for tissue abrasions, swelling, slipping – Pad well to prevent pressure necrosis – Higher incidence of synostosis especially in distal third of radius/ulna – Prolonged use can decrease ROM or patagial contracture – Chances of achieving and maintaining functional alignment are generally poor when managed by coaptation alone Coaptation- Body wrap – With or without Figure-of-8 bandage – Temporary stabilization of wing fractures – Treatment of shoulder girdle problems such as coracoid Fx or luxations – Stabilization of radius OR ulna fracture (increased risk of synostosis and non-union relative to surgical repair) – With metacarpal splint for treatment of distal wing fractures – Careful to allow respiratory movements Coaptation- Body Wrap Ponder and Redig 2016 Coaptation- Figure-of-8 Wrap – Stabilize wing Fx distal to elbow, or on reduced elbow luxations – Longer term use (>7-10 days) increases risk of complications- fibrosis and decreased ROM due to hyperflexion of carpus, fibrosis and contracture of patagium – Keep lightweight with minimal bulk – PT at least twice a week, more frequently if any decrease in ROM noted Coaptation- Figure-of-8 Wrap with Body Wrap Mitchell and Tully 2009 Coaptation- Curved Edge Splint – Moldable thermoplast or SAM Splint – Support for metacarpal Fx – Placed on ventral surface and curved up along the leading edge of the wing, sandwiched with tape, body wrap – Lateral edge bent up at 90 degrees, does not extend above the plane of the dorsal surface of the wing (does not wrap around the carpus) – Monitor for soft tissue swelling Coaptation- Curved Edge Splint Ponder and Redig 2016 Coaptation- Robert Jones – NOT recommended for wing injuries – Difficult to apply, uncomfortable for patient – Too heavy for the wing Coaptation- Tape Splint – Used in small birds for leg fractures Surgical Fixation – Usually better functional alignment – Increased capacity for normal use of limb during healing, preventing loss of range of motion due to soft tissue or tendon contracture, as well as improve facture healing Surgical Fixation – Fixation device should – Be rigid, lightweight, versatile, and removable – Stabilize the forces that apply tension, torsion, shearing, and bending movements to bone – Provide load-sharing with the fracture where possible, load- bearing when not Surgical Fixation Types – Intramedullary (IM) pin – External skeletal fixator (ESF) – Hybrid fixator ESF-IM – Plates and nails – Cerclage wires – Shuttle Pins Surgical Fixation- IM Pin – Provides excellent opposition to bending forces of a long bone and good alignment, applied relatively easily – Does NOT provide resistance to torsional, compressive and tensile forces, therefore typically used with coaptation or with ESF – Must secure pin so it does not fall out, or patient does not pull it out – Most common use of single pin is in radial fracture – Single pins should fill ½ to 2/3 of medullary cavity Surgical Fixation- IM Pin Bennett 1992 Surgical Fixation- ESF – Resists rotational movement, compressive and tensile forces, moderate bending; difficult to get good end-to-end alignment of the bone fragments – Critical to ensure that each ESF pin engages both bone cortices – Used alone when an IM pin cannot be used due to joint impingement, or in highly comminuted fractures with significant soft tissue compromise – If used alone, requires 2 ESF pins in each fracture segment, one close to the end of the bone and the other as close to the fracture as possible – Often used for metacarpal or ulnar fractures Surgical Fixation- ESF Bennett and Kuzma 1992 Surgical Fixation- Hybrid Fixator (ESF-IM tie-in) – Inexpensive, easily learned, lightweight, adaptable, and often very effective – Incredible strength and integrity, resisting all forces on bone, allows for good bone alignment – Consists of an IM pin, 2 ESF pins, and an external connector to join them – Additional ESF pins can be used if load-bearing needs to be handled by the fixator – Sequential dismantling of the fixator allows transfer of load-bearing to the bone, promoting bone healing ESF-IM tie-in Ponder and Redig 2016 Intra-Op Notes – Verify pin placement with intra-op radiographs – Check rotational alignment of fracture with comparison to other wing – Check length of bone is correct,
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