Evaluation of Canine Orthopedic Trauma

Chapter 17


Evaluation of Canine Orthopedic Trauma



Clinical evaluation of the trauma patient for orthopedic injury is multifaceted. Although outward injuries such as fractures may be apparent, an awareness of more insidious threats is also of critical importance. Cardiovascular stability and the identification of associated injuries should be prominent considerations inasmuch as mortality rates for trauma patients are reported at 7% to 12.5% (from spontaneous death or euthanasia). Additionally, between 39% and 60% of small animals that present with fractures have recognizable thoracic trauma. This chapter emphasizes the diagnostic approach to the dog with orthopedic trauma (see Chapter 18).


Recognition and stabilization of life-threatening conditions may delay a thorough orthopedic evaluation. Also, key components of a typical orthopedic evaluation such as gait assessment can be especially challenging and may require support with a sling or harness. Other barriers to a complete examination include bandages and splints that may have been placed due to lacerations, abrasions, or fractures. Therefore completion of a thorough orthopedic examination may need to be performed over time.


Historical information helps clarify the cause of injury and expected associated injuries. For example, patients with gunshot wounds have a higher incidence of additional penetrating injuries to the abdomen or thorax, whereas patients who suffer vehicular trauma have a high incidence of pelvic trauma. These incidence and risk factors impact the diagnostic workup and treatment performed. Preexisting conditions should not be overlooked because they may become especially relevant following trauma and are often forgotten in the excitement of patient stabilization.



Orthopedic Examination


Although a complete gait and mobility workup may not be feasible immediately following trauma, standing weight-bearing assessment remains an important tool for appraising a patient’s neurologic and orthopedic functions. The position of the limbs with the patient in a standing position allows the clinician to assess muscle strength, girth, and tone and search for any neurologic injury such as radial nerve injury or brachial plexus trauma. If functional changes are noted in the limb, further neurologic evaluation should be pursued including spinal reflexes and sensation.


Additional assessment involves lifting each limb to determine the amount of weight placement, proprioception, and weight balance between limbs. Further neurologic evaluation is indicated if weakness or conscious proprioceptive deficits are found. Limbs should be compared for differences in symmetry. The vertebral column should be examined for any derangement. Weight distribution, posture, weight bearing, and limb positioning should be assessed from multiple perspectives (from both sides, front, and back). Many orthopedic injuries have characteristic postural changes easily recognized in a standing position (as with coxofemoral luxation). A systematic approach or checklist is likely to improve efficiency and accuracy of diagnosis. The standing examination provides the most direct and specific assessment of weight bearing, symmetry, and function.



Palpation


Starting with the cervical spine, one can manipulate and palpate the osseous and muscular structures to detect discomfort. The clinician should flex and extend the neck through full range of motion, including lateral, dorsal, and ventral flexion. The spine should be palpated throughout its extent. In addition to the spine, pelvis, forelimbs, and hind limbs should be assessed carefully and systematically to include palpation of bone, ligament, and muscles and evaluation of nervous system function.



Examination of the Forelimbs


Palpation of the forelimbs should include palpation of each scapula for normality and symmetry. The spine of the scapula serves as an excellent barometer for assessing forelimb muscle atrophy, an indicator of preexisting forelimb lameness. It is useful to compare both muscular tone and development especially near osseous landmarks such as the spine, acromion process, and the greater tubercle of the humerus.


The examiner should flex and extend all forelimb joints, including the shoulder, elbow, and carpus and each phalange. The latter also should be assessed carefully for swelling. Each forelimb joint should be evaluated for stability, displacement, or increased joint laxity. Shoulder luxations often demonstrate displacement, but subluxations are more subtle and require stress maneuvers to reveal instability. Elbow luxations are predominantly displaced laterally, with observable and palpable displacement of the radial head. Injuries to the carpus commonly produce hyperextension of the joint, which often requires stressed-view radiographs to document fully.


Limb fractures (of the humerus, radius, or ulna) often produce mechanical instability and displacement. Mechanical integrity of many of the long bones can be assessed through torsional stress. This is done by stabilizing the proximal aspect and rotating the distal aspect of the bone. The distal joint can be used as a lever when the limb is in flexion. For example, humeral integrity is evaluated by palpating the greater tubercle, which stabilizes the proximal humerus. By rotating the elbow to 90 degrees the antebrachium is used as a lever to apply controlled torsional stress to the humeral shaft. Rotation of the distal aspect of the humerus should produce proportional torsional rotation at the greater tubercle.


Palpation of osseous structures is performed not only to detect displacement but also to identify discomfort (osteodynia) caused by bone contusion, “greenstick” fracture, or nontraumatic preexisting disorders such as neoplasia or panosteitis.



Shoulder


While assessing shoulder range of motion, the clinician should stabilize the scapula. To test shoulder integrity the acromion process is stabilized while the joint is placed in extension. Assessment for medial shoulder stability is complex due to contributions of the collateral ligaments and the additional support of regional muscles. Sedation is advantageous, with the patient in lateral recumbency. With the scapula stabilized and the shoulder in extension, valgus stress is applied on the limb by lifting the limb upward (in abduction) to determine medial stability. Normal glenohumeral abduction angles are less than 30 degrees and using the opposite shoulder for comparison is helpful. Assessment of lateral collateral stability is more difficult due to interference of the thorax and is done with varus stress applied. The shoulder range of motion, degrees of varus and valgus freedom, and rotation movement should be compared with the contralateral limb. Many shoulder joints pop or click without significance, but any translation of the humeral head in relationship to the acromion process is abnormal.

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Jul 18, 2016 | Posted by in PHARMACOLOGY, TOXICOLOGY & THERAPEUTICS | Comments Off on Evaluation of Canine Orthopedic Trauma

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