42. Fractures of the pelvis. Diagnosis and therapy.

What is the pelvis?

The bony structure that forms the posterior part of the trunk and connects the spine to the hind limbs

What are the three main bones that make up the pelvis?

Ilium, ischium, and pubis

What is the ilium?

Largest & most cranial part of pelvis, extends forward & upward. Forms "wings" of pelvis & articulates with the sacrum at sacroiliac joint

What is the ischium?

Located caudally, forming the lower part of the pelvis. Provides attachment points for several muscles & forms bony prominence known as ischial tuberosity.

What is the pubis?

Smallest of three bones, located ventrally. Pubic bones from both sides meet at pubic symphysis, a fibrous-cartilaginous joint in the midline.

What is the acetabulum?

The deep socket formed by the ilium, ischium, and pubis, which articulates with the caput femoris, forming the hip joint

What are the joints associated with the pelvis?

1. Sacroiliac joint

2. Hip joint

Which joint connects the sacrum to the ilium?

Sacroiliac joint

Which joint is formed between the acetabulum and the femoral head?

Hip joint

What are some functions of the pelvis?

1. Supports weight of body during movement & when standing.

2. Protects organs like bladder, rectum, & reproductive organs.

3. Provides attachment sites for muscles of hind limbs & trunk.

How common are pelvic fractures in small animals?

Relatively common (20-30%)

What is a common characteristic of pelvic fractures?

Most are multiple, involving three or more bones.

What is the effect of the many muscles surrounding the pelvis?

Open fractures are less common, as muscle helps stabilise it → heal fast → malunion (common)

What are some common causes of pelvic fractures?

Motor vehicle accidents, gunshot injuries, animal fights, falls.

What are the six anatomical areas used to categorise pelvic fractures?

1. Sacroiliac fracture/luxation: Lux of sacroiliac joint, fracture of sacral wing, partial sacroiliac luxation w/ partial fracture of sacral wing

2. Iliac wing fracture: Fracture of cranial non-weight bearing & non-articular portion of iliac wing

3. Ilial body fracture: Ilial fracture between sacroiliac joint & acetabulum

4. Acetabular fracture: Any fracture involving articular surface, may extend into ilium & ischium

5. Ischial fracture: Fracture of ischial body or ramus or fracture/avulsion of tuber ischium

6. Pelvic floor fracture: Fractures of pelvic symphysis, pubic body or ramus, & ischial ramus.

What is a stable pelvic fracture?

One that does not involve the main joints (iliosacral, acetabular).

What are the types of non-stable fractures?

1. Segmental fractures: body of ilium, pubis & ischium are fractured, or fracture of symphysis & ilio-sacral junction

2. Acetabular fractures: one or more fracture lines, weight bearing on limb is faulty

What are complications of pelvic fractures?

1. DJD (acetabular fractures → change articular congruity)

2. Concurrent injuries to vital organs (should be addressed before definitive fracture management)

What are some clinical signs of pelvic fractures?

Lameness, limb weakness, haematomas, inability to walk/stand.

How are pelvic fractures diagnosed?

1. Physical exam of entire body

   1. Focus on complicating injuries (traumatic lung injuries, myocarditis, pneumothorax, rupture of bladder or urethra, fractures of femoral head or neck, fracture of spine with neurological deficits)

   2. Palpation of pelvic bones

2. Neurological exam (test reflexes, proprioception, withdrawal, perineal reflex etc)

3. Imaging diagnostics: CT, X-ray.

What are some differential diagnoses for pelvic fractures?

Growing dog growth plates.

What are the treatment options for pelvic fractures?

Conservative (75%) or surgical.

What are examples of conservative treatments for pelvic fractures?

1. Cage rest, limitation of activity (Well-padded kennel to prevent decubital ulcers)

2. Ensure urination (catheterisation) & defecation

3. Physical rehabilitation

4. NSAIDs (meloxicam, carprofen)

5. Supportive therapy (vitamins, calcium)

When is conservative treatment indicated for pelvic fractures?

Stable, non-displaced or minimally displaced iliac fractures, sacroiliac fracture-separation.

When is surgical treatment indicated for pelvic fractures?

Non-stable fractures, dislocations, multiple fractures, fractures involving other organs.

What types of surgical methods are used for treatment of pelvic fractures?

Repaired according to location, with use of bone plates, lag screws, & Kirschner wires

What is the most common type of iliac fracture?

Long oblique fracture of the midbody.

What are the methods of fixation for ilial body fractures?

1. Lateral bone plate placement

2. Bone forceps & rotational movement to counteract overlap of oblique fragments

What are some types of acetabular fractures?

Transverse, oblique, comminuted.

Which acetabular fractures are considered unrepairable?

Those with severe medial wall fracture and significant femoral head displacement.

What are the treatment options for unrepairable acetabular fractures?

1. Femoral head and neck excision

2. Total hip replacement (at later date)

Which type of sacroiliac fracture is most common?

Unilateral separation.

What is the first-choice treatment for sacroiliac fracture?

Conservative.

What are some methods of fixation for ischial fractures?

Small plates, lag screws, K-wires.

When is internal fixation indicated for symphysis pelvis fractures?

When associated with abdominal rupture.

In which age group are symphysis pelvis fractures most common?

Young animals.

When is only a conservative treatment indicated for treatment, not surgery?

When the fracture is stable and none of the important ligaments are involved and if the animal is young and healthy.

Why is surgical treatment of pelvic fractures generally avoided?

Strong muscles can compensate

What structures are also commonly affected with pelvic fractures?

Bladder.

How is bladder rupture diagnosed?

Cystography with contrast.

What would be used to treat an ileosacral break?

Screws or pins.

What are examples of the main muscles of the pelvis?

1. Muscles of the Pelvic Girdle (External Pelvic Muscles)

   • M. gluteus superficialis

   • M. gluteus medius

   • M. gluteus profundus

   • M. tensor fasciae latae

2. Muscles of the Hip (Lateral Rotators of the Femur)

   • M. piriformis

   • M. obturatorius externus

   • M. obturatorius internus

   • M. gemelli

   • M. quadratus femoris

3. Muscles of the Pelvic Floor (Internal Pelvic Muscles)

   • M. coccygeus

   • M. levator ani