Fractures of the pelvis are very common in dogs and cats, especially in younger animals. They are most often caused through trauma from road traffic accidents. Exceptions to this are stress fractures of the acetabulum, occasionally seen in racing Greyhounds, minimally displaced fractures in immature animals, as well as pathological fractures due to neoplasia.

The pelvis is composed of the paired ilium, ischium and pubis. These three bones are fused together to form the acetabulum to articulate with the femur. The ilial bones articulate on either side with the sacrum forming the tight bilateral sacroiliac joints. During walking the weight is transferred through the sacroiliac joints over the ilium to the acetabulum. This so-called weightbearing axis is important to consider when assessing pelvic fractures. Due to the box-like shape of the pelvis, fractures (or luxations) most commonly occur in more than one place. The joints are frequently involved when there is trauma to the pelvis and may complicate the method of treatment and the animal's prognosis.

Clinically, dogs and cats with pelvic fracture most often present severely lame; bilaterally affected animals might even be unable to bear weight on the hindlimbs at all, depending on the extent and severity of injuries.

Because most pelvic fractures result from severe trauma, concurrent injuries are frequent. In the short term the soft tissue injuries are more significant than the fractures and need to be treated before fracture repair should be attempted. A thorough physiological, orthopaedic and neurological examination is mandatory before a decision for further treatment can be made. The following points especially need to be considered in trauma patients with pelvic fractures:

 Thoracic radiographs should be taken to detect thoracic injuries commonly found in trauma patients.

 The incidence of urinary tract trauma secondary to pelvic fractures is nearly 40%, with bladder and urethral ruptures being the most common injuries. The presence of a palpable bladder and the ability of the patient to urinate do not preclude injuries to the lower urinary tract. In addition to plain lateral abdominal radiographs, further diagnostics including a retrograde urethrocystogram and intravenous pyelogram may be indicated.

 Ultrasonography can help to detect other underlying abdominal injuries.

 A rectal examination should also be included in the routine work-up to rule out rare, but potentially fatal, rectal perforation.

 Peripheral nerve injury is common in patients with pelvic fractures, although they are, fortunately, frequently not permanent. Injury to the sacrococcygeal nerve roots can manifest in bladder paralysis and urinary incontinence. Bladder function will often return, but the owners need to be warned that this may take up to several months and cannot be guaranteed.

 Absent deep pain in the hindlimbs and an absent anal reflex are bad prognostic signs and must not be overlooked.

 Lateral and ventrodorsal radiographs of the pelvis should be taken to assess the pelvic injuries.

Depending on the specific fracture type, location and age of the animal, pelvic fractures may be managed conservatively or surgically. Various pelvic fractures can be successfully managed conservatively, but there are clear indications for some fractures, which should be surgically repaired in order to avoid long-term complications such as severe osteoarthritis with articular fractures or constipation due to pelvic canal narrowing. Additionally there is a group of pelvic fractures which ideally should be treated surgically, because surgery will nearly always help to reduce the hospital stay, decrease nursing requirements and alleviate pain. Financial restraints or other severe injuries making the patient not suitable for anaesthesia are possible reasons that these cases are nonetheless treated conservatively, often even with comparable long-term results.

It is important to evaluate every patient in its entirety. Inappropriate case management, inadequate surgical stabilisation, or poor aftercare can lead to complications such as non-unions or malunions, which can result in narrowing of the pelvic canal leading to constipation, osteomyelitis, osteoarthritis of the hip joint, or even a non-functional leg.

Indications for conservative treatment of pelvic fractures are:

 Minimally displaced ilial fractures

 Minimally displaced sacroiliac luxations

 Most pubic and ischial fractures

The pelvis cannot be adequately immobilised in a cast or splint to allow proper healing. Therefore conservative management always entails strict cage rest for 4-8 weeks depending on the age of the animal and the severity of injuries. Ambulation should be restricted to short lead walks only, supported by an abdominal sling. Soft padded bedding should be provided to avoid pressure sores. The patient's urination and defecation need to be closely monitored and assisted as needed. Appropriate analgesia forms a central part of the treatment. Most often combinations of opioids and non-steroidal antiinflammatory drugs will be helpful to provide an adequate level of pain relief, especially during the first time after trauma.

Indications for surgical repair of pelvic fractures are:

 Most ilial fractures with unstable acetabular fragment

 Bilateral fracture luxation

 Fractures resulting in significant narrowing of the pelvic canal of 50% or more

 Acetabular fractures

 Fractures in working dogs or breeding females

 Multiple limb fractures

Repair of the fractures becomes difficult after 7-10 days due to initial fibrosis at the fracture and muscle contraction. Postoperative management includes strict cage rest for usually 4-6 weeks. The recommendations given for conservative management of pelvic fractures regarding pain relief, monitoring and assisting in urination and defecation, controlling exercise are also true for postoperative considerations.

In the lecture recommendations regarding specific fracture scenarios will be given and nursing requirements preventing possible complications will be discussed in detail.

References

1.  Innes J, Butterworth S. Decision making in the treatment of pelvic fractures in small animals. In Practice 1996; May: 215-221.

2.  Miller A. Decision making in the management of pelvic fractures in small animals. In Practice 2002; February: 54-61.

3.  Tomlinson JL. Pelvic fractures. In: Slatter, DH. ed. Textbook of small animal surgery (third edition). Philadelphia: WB. Saunders, 2003; 1989-2001.