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tvpjournal.com | July/August 2015 | TodAy's VeTerinAry PrAcTice A PrAcTiTioner's Guide To FrAcTure MAnAGeMenT Peer reviewed 19 The 5 main forces that act on bone are listed in Table 1. • Tensile (tension) forces act to lengthen the bone, while compressive forces shorten the bone. • Shearing forces are typically parallel or tangential to the bone, while torsional forces act to twist bone about its long axis. • Bending forces create a convex side of the bone (bone loaded in tension on the convex side) and a concave side (bone loaded in compression on the concave side). Bending forces are typically referred to as moments. FRACTURE DIAgNOSIS & ClASSIFICATION Patient Stabilization Because most fractures result from trauma, it is important to ensure patient stability prior to focusing on the fracture. Ideally, for any patient that presents after a traumatic event: 1. Check and stabilize vitals (temperature, pulse quality and heart rate, respiration rate, blood pressure, pulse oximetry), if needed. 2. Perform thorough physical, orthopedic, and neurologic examinations. 3. Pursue initial diagnostics, including blood analysis, thoracic and abdominal radiographs, and an AFAST ultrasound. 4. Resolve any life-threatening issues, which means that surgery may need to be delayed for several days due to conditions, such as pulmonary contusions or hypovolemia. 5. Administer proper analgesia as soon as possible: Ideal analgesics are pure mu opioids, such as: • Morphine: Dogs, 0.5 to 2 mg/kg; cats, 0.05 to 0.4 mg/kg; IV or IM Q 6 to 8 H • Hydromorphone: Dogs/cats, 0.05 to 0.2 mg/kg IV or IM Q 6 to 8 H • Oxymorphone: Dogs/cats, 0.05 to 0.2 mg/kg IV or IM Q 6 to 8 H • Methadone: Dogs, 0.05 to 0.3 mg/kg; cats, 0.1 up to 0.3 mg/kg; IV or IM Q 6 to 8 H • Fentanyl: Dogs/cats, 2 mcg/kg loading dose followed by 2 to 10 mcg/kg/H CRI (caution with cats). Other opioids, such as butorphanol, do not typically provide adequate analgesia. Post Stabilization Diagnostics Once the patient is deemed stable: 1. Obtain a thorough history: It is important to separate traumatic from pathologic fractures by determining the cause of the fracture, such as hit by car or fall from a height. 2. Evaluate physical examination fndings: Signs of fractures include pain, swelling, reluctance to bear weight, crepitus, and/or angulation deformities. 3. If the patient is nonambulatory on the affected limb, perform a complete neurologic examination to rule out any neurologic defects, such as: » Radial nerve damage—seen with distal humeral fractures » Sciatic nerve damage—seen with ilial fractures. Radiographs are the mainstay for determining fracture type and location. Key radiographic projections are orthogonal views, including lateral, craniocaudal, and oblique (if needed) views. If only a lateral view is taken, some fractures, such as T-Y humeral fractures that involve both the articular surface of the distal humeral condyle and the supracondylar region, will be missed (Figure 1). Fracture Classifcation To improve communication between veterinarians and clients, and between veterinarians themselves, bone is stronger when loaded rapidly versus slowly, and when loaded longitudinally versus transversely. therefore, bone is stiffer and stronger when loaded rapidly and longitudinally. FIGURe 1. Lateral radiograph of the antebrachium in a young dog presenting for right forelimb lameness; this radiograph does not reveal any evidence of fracture or pathology (a). Craniocaudal radiograph of the same right forelimb, revealing a Salter Harris IV fracture of the distal humeral condyle (b). a b