Pelvic Ring Injuries

A pelvic ring injury disrupts the osteoligamentous ring formed by the sacrum, sacroiliac joints, innominate bones and symphysis pubis. Because the pelvis is a ring, a visible anterior fracture should prompt a deliberate search for a posterior fracture, SI ligament injury or occult instability.

This is the general pelvic-ring page, covering all mechanisms (lateral compression, anteroposterior compression, vertical shear and combined). The anteroposterior-compression "open-book" pattern - symphyseal diastasis with its specific binder, haemorrhage-control and fixation priorities - has a dedicated deep-dive on the Open Book Pelvis page.

Who. High-energy pelvic ring injuries are uncommon compared with other fractures, but they carry disproportionate risk because they occur in polytrauma and can be associated with major haemorrhage. A second important population is the older patient with an osteoporotic fragility fracture, where the immediate problem is often pain, immobility and loss of independence rather than exsanguination.

Why it matters. Early deaths are usually haemorrhagic. Stable injuries can mobilise, while rotational and vertical instability need mechanical control and often operative fixation. Urethral, bladder, rectal, vaginal, neurological and Morel-Lavallee injuries change timing, fixation and complication risk.

The first principle. Pelvic ring injuries are not managed by naming the fracture first. They are managed by deciding whether the patient is bleeding, whether the posterior ring is unstable, and whether contamination or associated injuries change the sequence.

The posterior ring. The posterior SI complex is the main posterior tension band and gives vertical stability, so its complete disruption usually needs posterior fixation. The sacrospinous and sacrotuberous ligaments resist external rotation and vertical shear; their failure separates APC-1 from APC-2 and contributes to instability.

The anterior ring. The anterior ring and symphysis control rotational opening. A symphyseal plate closes the front but cannot stabilise posterior vertical failure alone.

Where the blood comes from. The pelvis bleeds from cancellous bone, the venous plexus and internal iliac arterial branches. The presacral venous plexus and cancellous bone are the major venous and bone sources, and they respond to binder, packing and mechanical stability. The internal iliac branches are the arterial source: a CTA blush or persistent shock may require angioembolisation.

Nerves and viscera. The lumbosacral trunk and sacral roots carry motor, sensory and sphincter function, so neurology must be documented before and after reduction or screw fixation. Injury to the urethra, bladder, rectum or vagina changes catheterisation, contamination control and operative sequencing.

Young-Burgess is a mechanism classification. Its value is that it predicts direction of force, likely ligament failure, bleeding risk and initial fixation direction. Lateral compression (LC) is an internal rotation injury that closes the ring; anteroposterior compression (APC) is an external rotation injury that opens it; vertical shear (VS) displaces one hemipelvis vertically. Treatment by pattern is set out under Definitive Treatment.

APC: the symphysis is visible, the SI joint decides. Symphyseal diastasis is the obvious finding, but posterior SI disruption decides severity. An APC-3 injury is not a symphysis-only injury.

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LC: the label is not enough. The key question in any LC injury is whether the posterior sacral injury is incomplete, complete, displaced or dynamically unstable. An LC-1 is often stable, but sacral completeness, displacement, dynamic instability and the ability to mobilise all matter.

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VS: the posterior ring has failed. Cranial migration of the hemipelvis indicates posterior ring failure and the need for posterior mechanical control.

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Tile is a stability classification. It is especially useful when explaining why an anterior-only construct may be inadequate: Tile B rotates, Tile C rotates and translates.

• Type A - stable ring. Avulsion, isolated iliac wing or minimally displaced stable ring injury; usually non-operative.
• Type B - rotationally unstable, vertically stable. APC-2 and some LC injuries; anterior fixation often matters, and the posterior ring still needs assessment.
• Type C - rotationally and vertically unstable. Vertical shear, complete SI disruption or an unstable sacral fracture; posterior fixation is essential and anterior fixation supports the construct.

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Fragility fractures of the pelvis are low-energy injuries in osteoporotic bone. The treatment goal is pain control, restoration of mobility and prevention of loss of independence as well as union.

Sacral fractures

Denis zones. Classify every sacral fracture by Denis zone. The zone predicts both the deficit to examine for and the fixation corridor, and neurological risk rises from lateral to central:

• Zone I (alar, lateral to the foramina) - the commonest zone. Neurological injury is uncommon (roughly 6%), but an upward-driven ala can trap the L5 nerve root against the L5 transverse process.
• Zone II (transforaminal, through the neural foramina) - intermediate neurological risk (roughly 28%), typically L5, S1 or S2 radiculopathy. Vertical shear through this zone is unstable.
• Zone III (central, involving the spinal canal) - the highest neurological risk (roughly 57%), characteristically bowel, bladder and sexual dysfunction (cauda equina) from canal compromise.

Document perianal sensation, anal tone and sphincter and voiding function, especially in Zone III. Foraminal comminution (Zone II) and canal involvement (Zone III) change iliosacral screw safety and may mandate decompression; Zone III with cauda equina symptoms is the one that may need decompression as well as stabilisation.

Spinopelvic dissociation. Here the spine is mechanically separated from the pelvis. Bilateral vertical (transforaminal) sacral fractures are connected by a transverse fracture, producing a U-, H-, lambda- or T-shaped sacrum. The classic mechanism is an axial load (fall or jump from height), hence the association with calcaneal and thoracolumbar fractures.

Why it is dangerous. The upper sacrum and spine flex forward on the lower sacrum and pelvis, causing kyphotic sacral deformity and canal narrowing with a high rate of cauda equina or sacral root injury (often Denis Zone III). It is frequently missed because the AP pelvis looks deceptively intact: look for a paradoxical inlet appearance of the upper sacrum on the AP film and confirm with CT and sagittal reconstructions.

How it is fixed. It is a posterior tension-band failure that iliosacral screws alone may not control. Highly displaced or kyphotic patterns, and those with progressive neurology, are stabilised with lumbopelvic ("triangular") fixation - pedicle screws into L5/sacrum connected to iliac screws - with sacral laminectomy or decompression if there is cauda equina compromise.

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Physiology. Hypotension, tachycardia, transfusion need, lactate, a falling base excess and the response to the binder decide between CT and urgent haemorrhage control. A shocked patient with a pelvic fracture has pelvic bleeding until another major source is proven, and needs a binder, blood products, a senior trauma call and the haemorrhage-control pathway.

Mechanism. Motorcycle crash, side impact, crush, fall from height, pedestrian impact or an elderly low-energy fall. The mechanism predicts LC, APC, VS, open injury and associated trauma.

Skin and perineum. Look for a perineal wound, scrotal or labial swelling, a Morel-Lavallee lesion, degloving, and rectal or vaginal blood. An open pelvis or soft tissue injury changes antibiotics, debridement and fixation staging.

Urology. Blood at the meatus, gross haematuria, inability to void and suprapubic pain change catheter and imaging decisions: a retrograde urethrogram or CT cystogram may be needed before a catheter strategy is chosen.

Neurology. L5 weakness, foot drop, sacral sensory loss, saddle symptoms, and anal tone when indicated. Recording them documents any lumbosacral plexus or sacral root injury and protects against a missed iatrogenic change.

Examination. Inspect for leg length asymmetry, rotational posture, pelvic and flank bruising, open wounds, genital swelling and abdominal distension. Do not repeatedly compress, distract or spring the pelvis: if the mechanism, pain pattern, deformity or physiology suggests a pelvic ring injury, clinical suspicion is enough to bind, image and move to resuscitation. Before transfer or fixation, document binder position, distal pulses, lower-limb neurology, perineal signs, urology signs and skin condition.

Differential diagnosis of the painful or injured pelvis

The key decision is response to resuscitation. A non-responder needs haemorrhage control, not a perfect classification. The open pelvic fracture has its own sequence, set out in its own section below.

The tools. Angioembolisation treats arterial bleeding; it does not close pelvic volume or stabilise the posterior ring.

Non-operative care is appropriate for stable patterns. It must still include analgesia, a mobilisation plan, VTE prevention, repeat imaging when symptoms demand it, and treatment of osteoporosis in fragility injuries.

Operative care is indicated for unstable patterns, unacceptable displacement, failure of mobilisation in selected injuries, open fracture needs and associated injuries that require surgical control.

These are practical operative principles. Exact implants and sequence depend on patient physiology, fracture morphology, local trauma resources and surgeon experience.

These must be actively searched for. Do not pass a urethral catheter blindly when there is blood at the meatus, perineal bruising or high suspicion of posterior urethral injury.

A different risk profile. An open pelvic fracture communicates with a perineal, rectal, vaginal or major soft tissue wound, and combines haemorrhage, contamination, soft tissue loss, urogenital injury and possible rectal or vaginal injury. Early death is usually bleeding; later death is often sepsis and organ failure.

The sequence. Senior multidisciplinary coordination from the start:

1. Give broad antibiotics and tetanus prophylaxis early.
2. Control haemorrhage with blood products and binder, packing, external stability or angio as required.
3. Inspect the perineum, rectum and vagina; involve colorectal, urology and gynaecology when relevant.
4. Debride devitalised tissue and control the wound and contamination. Faecal diversion is considered for rectal injury or major perineal contamination.
5. Use staged fixation if definitive implants would cross contaminated or compromised tissue.

Fixation. Temporary stability is often needed early. Definitive internal fixation should respect the contaminated zone and soft tissue viability.

How it fails. Delayed haemorrhage control, missed rectal injury, inadequate debridement, pelvic sepsis and poorly planned implants through contaminated tissue.

The same follow-up applies after operative and non-operative treatment.

Weight bearing. Base it on posterior ring stability, fixation strength, bone quality and associated injuries. One rule does not fit LC-1, APC-2, APC-3 and VS injuries.

Neurology. Repeat the lower-limb and perineal neurological examination after reduction or fixation. A new deficit may indicate a screw, reduction or haematoma problem.

Wounds. Inspect binder pressure areas, pin sites, Morel-Lavallee lesions and open fracture wounds, because soft tissue failure drives infection and delayed reconstruction.

VTE prevention. Pelvic trauma has a high thromboembolic risk. Use mechanical and pharmacological prophylaxis when bleeding risk allows.

Function. Early sitting, transfers, chest care and progressive mobilisation with physiotherapy. Outcome depends on whole-trauma rehabilitation, not only radiographic union.

Fragility care. Osteoporosis treatment, falls assessment and geriatric rehabilitation prevent recurrent fractures and loss of independence.

Better prognosis goes with early haemorrhage control, accurate posterior reduction, stable fixation, recognised urology and neurology issues, and effective rehabilitation.

Worse prognosis goes with open pelvic fracture, prolonged shock, pelvic sepsis, vertical instability, neurological injury, severe associated trauma and malunion.

Global epidemiology

Side-by-side guidance

Registry and resource-setting notes