Assessment and management of pelvic fractures in dogs and cats (Proceedings)
Pelvic fractures are common, representing 20-30% of fractures in small animals. They are most commonly seen in young, healthy dogs and cats subsequent to being hit by car. Concurrent injuries to vital organs are very common, and should be addressed before definitive fracture management. Not all fractures require surgical correction, and many can heal well with conservative management. Appropriate assessment and management of pelvic fractures requires an understanding of the anatomy and biomechanics of the pelvis.
Presentation and Physical Examination
Patients with pelvic fractures may present with a mild to non weightbearing lameness. In some cases, they may be non-ambulatory. They typically present with a trauma history and almost always have a second injury, whether orthopedic or soft tissue. While pelvic fractures are painful and can result in significant blood loss, their stabilization comes second to treatment of immediately life-threatening injuries.A thorough physical examination to rule out thoracic and abdominal injury is imperative. A minimum database of thoracic radiographs, complete blood count, serum chemistry, and urinalysis are also indicated. Some concurrent injuries are obvious on initial presentation. Others may be more insidious and may not be diagnosed until later in the hospitalization and recovery period, when they become more apparent. These include pulmonary contusions, diaphragmatic hernia, and urinary tract trauma. Urinary tract trauma is particularly common with pelvic fractures, and has been reported in over ⅓ of cases. A palpable bladder on physical examination or a visible bladder on abdominal radiographs do not necessarily rule out urinary tract trauma. If physical signs, urinalysis or serum chemistry suggest urinary tract compromise, further imaging by contrast studies or ultrasound may be indicated.
Physical examination of the pelvis should include assessment of pelvic symmetry, of the patient's ability to stand, of sacroiliac instability, and of pain on direct palpation. A rectal examination should be performed to assess for rectal perforation or pelvic canal narrowing. The hindlimbs should be evaluated for concurrent fractures, and the stifle and tarsus assessed for palpable instability. This is especially true for any animal that is non-ambulatory.
A complete neurologic examination is indicated, as peripheral nerve and nerve root injuries are common with pelvic fractures. Intact cutaneous sensation to the medial and lateral digits can help confirm integrity of the femoral and sciatic nerves and their spinal nerve roots. Use caution when interpreting myotactic reflexes and proprioceptive testing in pelvic trauma patients. Apparent deficits may musculoskeletal rather than neurologic injury. Trauma to sacral nerve roots may cause urinary incontinence. While incontinence may not be immediately apparent on examination, evaluation of perineal sensation, perineal reflex, and tail tone can help to evaluate sacral and caudal nerve roots. Fortunately, most neurologic deficits seen with pelvic fractures are transient. However loss of perineal sensation, anal tone, or hindlimb deep pain sensation are cause for cause for concern over recovery. This should be conveyed to the owner at initial evaluation.
Anatomy and Fracture Appearance
In conjunction with the sacrum, the pelvis forms a 'box-like' structure. It consists of the paired bones of the ilium, acetabulum, ischium, and pubis. Single pelvic fractures are rare; damage and displacement at one point of this structure usually requires displacement at a second point. The exceptions to this are: fractures of the medial acetabular wall, certain pelvic fractures in young animals, and ischial tuberosity fractures.
The decision to treat pelvic fractures surgically or medically is based on a combination of radiographic evaluation, physical examination findings, and client/patient factors. Because it is surrounded by a significant muscle mass, the pelvis is a good biological environment for fracture healing. Even displaced fractures that are managed medically rarely proceed to non-union. Nonetheless, in many cases surgery is indicated to maximize functional outcome, relieve discomfort, and accelerate return to activity.
A systematic review of radiographs is important for planning treatment. Ventrodorsal and lateral radiographs typically are sufficient, but cross-sectional imaging may be helpful, especially in examining the acetabulum and sacrum. When evaluating radiographs, particular attention should be paid to the weight bearing segment- the path that transfers weight bearing forces form the hindlimb to the spinal column. The weight bearing segment includes the femoral head/neck, acetabulum, ilium, sacroiliac joint, and sacrum. Fractures in the weight bearing segment are candidates for surgical repair. Those for which surgery is especially indicated are: