Pelvic fractures

Overview

The pelvis is a strong ring of the sacrum and two innominate bones, held together at the pubic symphysis in front and the powerful posterior sacroiliac ligaments behind. Large forces are needed to break it, so pelvic ring fractures usually come with other major injuries and can cause life-threatening bleeding.

The ring usually breaks in two places; if you see one fracture, look for the second (often posterior, at the sacroiliac joint or sacrum).

Anatomy relevant to injury

• Stability depends mainly on the posterior sacroiliac complex (posterior SI, sacrospinous and sacrotuberous ligaments). Anterior injuries alone (symphysis, rami) leave the ring stable.
• Vessels: the presacral venous plexus and the internal iliac vessels (especially the superior gluteal and internal pudendal arteries) lie against the bone and are torn by displacement.
• Nerves: lumbosacral trunk and sacral roots cross the sacroiliac joint (sciatic nerve palsy with SI disruption or sacral fractures); femoral and obturator nerves; pudendal nerve.
• Viscera: bladder, urethra (membranous part fixed at the urogenital diaphragm), rectum, vagina.
• The retroperitoneal space can hold several litres of blood (over 3 L); haematoma can spread up to the mediastinum or down into the thigh when the pelvic floor is torn.

Types of pelvic fracture

Isolated (stable) fractures

• Avulsion fractures in young athletes: anterior superior iliac spine (sartorius), anterior inferior iliac spine (rectus femoris), ischial tuberosity (hamstrings). Rest.
• Isolated pubic ramus fractures in elderly osteoporotic patients after a simple fall: stable; analgesia and mobilisation. (In frail patients even low-energy fractures can bleed significantly.)
• Iliac wing fracture from a direct blow (Duverney): painful but the ring is intact.
• Stress fractures of the rami or sacrum (osteoporosis, long-distance runners).

Pelvic ring fractures: mechanism (Young-Burgess)

APC grades: APC I (symphysis widening under about 2.5 cm, stable); APC II (wider, anterior SI ligaments torn, rotationally unstable); APC III (anterior and posterior SI ligaments torn, hemipelvis disconnected, completely unstable). Apley quotes under 2 cm for APC I; definitions vary slightly between sources.

LC grades: LC I (rami + sacral compression, stable); LC II (plus iliac wing/crescent fracture); LC III ("windswept pelvis": LC on one side, open book on the other, e.g. run over).

Tile classification (stability)

Clinical assessment

Primary survey (ATLS)

• A pelvic fracture with hypotension and no other bleeding source = unstable ring until proved otherwise; apply a binder immediately.
• Unexplained hypotension in a trauma patient may be the only sign of pelvic bleeding.
• Mortality: about 1 in 6 for all pelvic fractures, about 1 in 4 with closed fracture and hypotension, about 50% with open pelvic fractures (ATLS).
• A haemodynamically unstable patient with a severe pelvic fracture has a very high rate of associated injuries, including intra-abdominal bleeding (Bailey quotes about 90% and 30%).

Examination

• Signs: pain, inability to stand, leg-length discrepancy and rotation (vertical shear shortens the leg without a hip injury), bruising of the flanks, scrotum, labia, perineum or thigh.
• Gentle palpation of the iliac crests, symphysis and SI joints once only. Do not repeatedly "spring" or rock the pelvis; it dislodges clot and worsens bleeding. Bailey advises against mechanical testing altogether: diagnose it on imaging.
• Perineum, rectum and vagina: look for lacerations (an open pelvic fracture), blood in the rectum, a high-riding prostate.
• Urethral meatus: blood suggests urethral injury.
• Neurology: sciatic (foot drop), femoral, obturator; perineal sensation and sphincter tone.

Imaging

Management of the bleeding pelvis

Where the blood comes from

• About 85% venous: the presacral venous plexus and cancellous fracture surfaces. Controlled by reducing pelvic volume and compression (binder, external fixator, packing).
• Arterial (branches of the internal iliac, e.g. superior gluteal, internal pudendal, obturator): less common overall, but more likely in the patient who stays unstable despite a binder. Controlled by angioembolisation.

Steps

1. ATLS resuscitation: airway, breathing, circulation; two large-bore cannulae; blood products early (massive transfusion protocol, balanced ratio), tranexamic acid, avoid excessive crystalloid; keep the patient warm.
2. Pelvic binder or folded sheet wrapped round the hips over the greater trochanters (not the iliac crests). It closes the open book, reduces pelvic volume and tamponades venous bleeding. Internally rotate and tie the legs together to help.
3. Look for other bleeding sources (chest, abdomen, long bones, external).
4. If still unstable:
   • Angioembolisation for arterial bleeding (if available quickly).
   • Preperitoneal (extraperitoneal) pelvic packing when angiography is delayed or unavailable, often with external fixation.
   • Laparotomy only if there is intra-abdominal bleeding (positive FAST); opening the peritoneum does not stop pelvic bleeding.
   • External fixator (anterior frame) or C-clamp (posterior) to stabilise the ring.
   • REBOA in some centres as a bridge.
5. Vertical shear: longitudinal skeletal traction on the affected leg helps restore position and stability.
6. Early transfer to a trauma centre if these facilities are not available.

Associated urogenital injuries

Urethral injury

• Almost always in men; the membranous (posterior) urethra is torn at the urogenital diaphragm, typically with anterior ring disruption (symphysis, bilateral rami: "straddle" fracture).
• Occurs in a small proportion of pelvic fractures (Bailey: about 1-2%).
• Signs: blood at the external meatus, inability to pass urine (retention, palpable bladder), perineal or scrotal bruising, high-riding (or impalpable) prostate on rectal examination.
• Do not insert a urethral catheter blindly; it may convert a partial tear into a complete one.
• Retrograde urethrogram (ATLS: mandatory if unable to void, a binder is needed, or there is blood at the meatus, scrotal haematoma or perineal bruising).
• Divert urine with a suprapubic catheter (percutaneous, often ultrasound-guided).
• Later: urethral stricture/disruption is repaired by delayed excision and end-to-end anastomosis (urethroplasty) after about 3-6 months. Long-term problems: stricture, erectile dysfunction, incontinence.

Bladder injury

Other associated injuries

• Rectal and vaginal tears make the fracture open: debridement, diverting colostomy, broad-spectrum antibiotics.
• Bowel and mesenteric injury, diaphragm rupture (Tile B and C), head, chest and long-bone injuries.
• Lumbosacral plexus / sciatic injury with SI disruption or sacral fractures (usually neurapraxia).

Definitive treatment of the pelvic ring

Acetabular fractures

• The femoral head is driven into the acetabulum: a blow on the side of the hip (fall from height) or on the front of the knee (dashboard, often with posterior hip dislocation and a posterior wall fracture).
• Columns: the anterior column shows as the iliopectineal line; the posterior column as the ilioischial line on the AP X-ray. Judet views (obturator oblique and iliac oblique) and CT define the pattern.
• Letournel classification: elementary (posterior wall commonest, posterior column, anterior wall, anterior column, transverse) and associated (e.g. both-column, T-shaped).
• Examine the sciatic nerve (especially with posterior wall fractures and dislocation) before and after treatment.
• Treatment:
  • Emergency: resuscitate; reduce any hip dislocation urgently; skeletal traction.
  • Non-operative: minimal displacement (under about 3 mm in the weight-bearing dome), fractures not involving the roof, elderly or unfit patients.
  • Operative (open reduction and internal fixation, ideally within days, in a specialist centre): displaced fractures of the weight-bearing area, unstable hip, incongruent joint, trapped fragments.
• Complications: post-traumatic osteoarthritis (the commonest long-term problem), avascular necrosis of the femoral head, sciatic nerve palsy, heterotopic ossification (prophylaxis with indomethacin or radiotherapy), venous thromboembolism.

Complications of pelvic ring fractures

• Early: haemorrhagic shock and death, urethral and bladder injury, bowel injury, nerve injury, infection (open fractures), DVT/PE (high risk; thromboprophylaxis).
• Late: persistent sacroiliac pain, leg-length discrepancy and malunion, urethral stricture, erectile dysfunction, incontinence, dyspareunia and obstetric problems in women.

Quick revision

• Ring breaks in two places; posterior SI complex decides stability.
• About 85% of bleeding is venous; arterial bleeding (internal iliac) in persistent shock → embolise.
• Hypotension + pelvic fracture → binder at the greater trochanters, transfusion, tranexamic acid.
• Still unstable: angioembolisation or preperitoneal packing ± external fixator; laparotomy only for abdominal bleeding.
• APC = open book (heavy bleeding); LC = commonest, bladder/urethra injury; VS = fall from height, completely unstable.
• Tile A stable; B rotationally unstable; C rotationally and vertically unstable.
• Blood at meatus + retention + high-riding prostate = membranous urethral rupture → no blind catheter, RUG, suprapubic catheter.
• Bladder rupture with pelvic fracture is usually extraperitoneal → catheter drainage.
• Acetabulum: iliopectineal (anterior column), ilioischial (posterior column); late OA, AVN, sciatic palsy, heterotopic bone.

Written by The House Job from standard references (Apley; Bailey & Love; ATLS).

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