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.
Treatment Planning
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:
- acetabular fractures
- significantly displaced ilial fractures
- sacroiliac luxations which are unstable or are displaced >50%
- fractures with significant narrowing of pelvic canal
- weightbearing segment fractures in dogs with multiple limb fractures or bilateral pelvic fractures
