Lateral Compression Pelvic Fracture

Lateral compression (LC) pelvic fracture is a pelvic ring injury from a lateral force that internally rotates the hemipelvis. It is the most common pattern of pelvic ring fracture. It follows a side impact road traffic collision or a fall from height in young adults, and a low energy fall in older adults with osteoporosis.

The Young-Burgess classification grades the injury. LC I: sacral compression (impaction) fracture with transverse pubic rami fractures on the same side, stable. LC II: a crescent (iliac wing) fracture with anterior and posterior sacroiliac ligament disruption on the impact side, rotationally unstable and vertically stable. LC III: an LC injury on the impact side with an opposite side external rotation injury (windswept pelvis), unstable.

Internal rotation reduces the pelvic volume, so haemorrhage is generally less than with the open book pattern, but LC II and LC III can bleed heavily. Associated injuries are bladder rupture, urethral injury, intra-abdominal organ injury, head and chest injury, and sacral plexus injury (L5 and S1 roots).

Complications are malunion (internal rotation, leg length discrepancy), nonunion, chronic pain, sacral insufficiency fracture, venous thromboembolism, urinary and sexual dysfunction, and, in older adults, loss of independence and mortality.

Pathophysiology.

The lateral force drives the hemipelvis medially, impacting the sacrum (LC I), fracturing the iliac wing (LC II), or crushing the sacrum with opposite hemipelvis opening (LC III). In older adults, osteoporotic bone fails at low energy and the sacral component is often missed on radiographs.

Pelvic and groin pain, inability to bear weight, and tenderness over the pubic rami and sacroiliac joints. Pain with gentle lateral compression of the iliac wings. Bruising over the flank or perineum. Examine the abdomen, urethral meatus, perineum and the lower limb neurology.

Assess haemodynamic status at once. In older patients with a low energy fall, look for anticoagulant use and for the cause of the fall.

• Anteroposterior pelvic radiograph, inlet and outlet views. The inlet view shows sacral impaction and internal rotation.
• CT of the pelvis (arterial phase when haemodynamics are unstable) is needed because sacral fractures are often occult. MRI in older adults with persistent pain and negative CT.
• Examination under anaesthesia with fluoroscopic manual internal rotation stress distinguishes LC I from LC II (over 1 cm of displacement indicates instability).
• Blood tests: haemoglobin, lactate, coagulation, creatinine; and urinary assessment when there is blood at the meatus.

Differential diagnosis.

• Open book and vertical shear pelvic fractures.
• Acetabular fracture and isolated pubic ramus fracture.
• Femoral neck fracture and hip dislocation.
• Sacral insufficiency fracture and intra-abdominal injury.

Resuscitation and haemorrhage control (unstable or shocked patients).

• Apply a pelvic binder centred on the greater trochanters (not the iliac crests) to any patient with a suspected unstable pelvic injury and shock. Keep the legs internally rotated with the feet taped together.
• Keep the binder on until definitive control in theatre. Do not spring the pelvis or log roll repeatedly. A binder may over compress an LC injury, so check the position on imaging.
• Two large bore intravenous lines (or intraosseous access). Permissive hypotension (systolic 80 to 90 mmHg) until bleeding is controlled, unless there is a head injury.
• Massive haemorrhage plan: red cells, plasma and platelets in a ratio of 1:1:1, adjusted to thromboelastography and laboratory results.
• Tranexamic acid 1 g intravenously over 10 minutes within 3 hours of injury, then 1 g intravenously over 8 hours (maximum 2 g in 24 hours). Reduce the dose in renal impairment (creatinine over 120 micromol/L). Monitor for seizures and thrombosis.
• Calcium chloride 10% 10 mL intravenously slowly after the first 4 units of red cells, then as needed to keep ionised calcium over 1.1 mmol/L. Use a central or large proximal vein, and monitor ionised calcium.
• Continued bleeding: preperitoneal pelvic packing, angioembolisation for arterial bleeding (CT arterial blush or persistent shock), and resuscitative endovascular balloon occlusion of the aorta (zone III) in selected patients.
• Anticoagulant reversal, warfarin: four factor prothrombin complex concentrate 25 units/kg (INR 2 to under 4), 35 units/kg (INR 4 to 6) or 50 units/kg (INR over 6), with vitamin K 5 mg intravenously slowly.
• Anticoagulant reversal, apixaban or rivaroxaban: andexanet alfa where available, or four factor prothrombin complex concentrate 50 units/kg.
• Anticoagulant reversal, dabigatran: idarucizumab 5 g intravenously.

By type.

• LC I (stable): non-operative. Mobilise within 24 to 48 hours with a walking aid and weight bearing as tolerated, with analgesia and physiotherapy. Admit older adults for pain control and rehabilitation.
• LC II and LC III, or over 1 cm of displacement on stress testing: fixation.
• Fixation of the posterior injury: iliosacral screws (7.0 mm cannulated) or sacroiliac plating. Use lag screws or plates for a crescent fracture. Fix the rami anteriorly by external fixator, internal subcutaneous fixator or plate.
• Weight bearing on the affected side is restricted (toe touch) for 6 to 8 weeks after fixation, then progressed.
• Open injury (perineal, vaginal or rectal wounds): debridement and faecal diversion for rectal injury, with antibiotic cover as for open pelvic injury.

Open pelvic injury (wounds communicating with the perineum, vagina or rectum).

• Intravenous co-amoxiclav 1.2 g every 8 hours with metronidazole 500 mg intravenously every 8 hours (or cefazolin 2 g every 8 hours with metronidazole). Start within 1 hour of injury. Continue for 24 hours after definitive wound control and for no more than 72 hours.
• Maximum co-amoxiclav 3.6 g daily. Give every 12 hours at creatinine clearance 10 to 30 mL/min. Check liver tests, and reduce the metronidazole dose in severe hepatic impairment.
• For gross contamination add gentamicin 5 mg/kg intravenously once daily for up to 72 hours. Check creatinine daily and a level before the second dose. Avoid or extend the interval at eGFR under 60 mL/min/1.73 m2.
• With severe penicillin allergy use clindamycin 600 mg intravenously every 8 hours (maximum 2.7 g daily) with gentamicin.
• Tetanus booster 0.5 mL intramuscularly if the last dose was over 10 years ago. Add tetanus immunoglobulin 250 units intramuscularly (500 units if over 24 hours since injury or heavily contaminated) when immunisation is incomplete or unknown.

Operative antibiotic prophylaxis. Cefazolin 2 g intravenously (3 g when weight is 120 kg or over) within 60 minutes before incision as a single dose. Repeat after 4 hours or blood loss over 1500 mL. With severe penicillin allergy, give vancomycin 15 mg/kg intravenously starting 90 to 120 minutes before incision as a single dose. Check levels and creatinine in prolonged cases.

Thromboprophylaxis. Enoxaparin 40 mg subcutaneously once daily. Start within 24 to 48 hours once bleeding is controlled and haemoglobin is stable. Continue for at least 28 days or until the patient is mobile.

Give 20 mg once daily at creatinine clearance under 30 mL/min. Adjust by anti-Xa level in obesity and renal impairment. Check the platelet count on days 5 to 14 for heparin induced thrombocytopenia. Use mechanical prophylaxis until then.

Analgesia.

• Paracetamol 1 g orally or intravenously every 6 hours (maximum 4 g daily; 3 g daily when weight is under 50 kg, with chronic alcohol use or hepatic impairment).
• Oral morphine 2.5 to 5 mg every 4 hours as needed for severe pain in older adults, and 5 to 10 mg in younger adults, for up to 5 days.
• Avoid exceeding 60 mg of morphine in 24 hours without senior review. Start 2.5 mg with age over 75 or eGFR under 30 mL/min/1.73 m2. Monitor sedation and respiration, and prescribe a laxative.
• Ibuprofen 400 mg orally every 8 hours with food for up to 5 days (maximum 1200 mg daily) once bleeding is excluded. Avoid with eGFR under 30 mL/min/1.73 m2, peptic ulcer, heart failure or anticoagulant use.

Secondary prevention after a fragility fracture.

• Alendronate 70 mg orally once weekly, taken fasting with a full glass of water and kept upright for 30 minutes, for 5 years then reassess (maximum 70 mg weekly).
• Check calcium, 25-hydroxyvitamin D and creatinine before starting and yearly. Avoid alendronate with eGFR under 35 mL/min/1.73 m2, uncorrected hypocalcaemia or oesophageal stricture.
• Zoledronic acid 5 mg intravenously over at least 15 minutes once yearly (for 3 years, then reassess) when oral therapy is not tolerated and eGFR is 35 mL/min/1.73 m2 or over. Check creatinine and calcium before each dose.
• Colecalciferol 800 to 2000 IU orally daily with dietary calcium to a total of 1000 to 1200 mg daily (maximum total 2000 mg daily). Correct vitamin D deficiency first.

Monitoring. Haemodynamics and haemoglobin in the first 24 hours for LC II and LC III. Radiographs after fixation, at 2 weeks, 6 weeks, 3 months and 12 months. Repeat imaging at 1 to 2 weeks when treated without surgery to detect displacement. Pain, mobility and function at each visit. Urinary function and leg length at follow up.

Referral and escalation. Refer every pelvic ring fracture beyond an isolated stable ramus fracture to orthopaedics the same day. Emergency escalation for shock, expanding perineal or flank haematoma, open wounds, or urethral injury. Early geriatric input for older adults.

Special groups.

• Older adults: low energy LC I fractures cause prolonged immobility. Mobilise early, treat pain, assess bone health, and investigate the fall.
• Pregnancy: left lateral tilt of 15 degrees, early obstetric input, and anti-D immunoglobulin in rhesus negative women with a Kleihauer test.
• Children: associated abdominal injuries are common.
• Kidney impairment: reduce tranexamic acid dose, avoid ibuprofen and bisphosphonates at eGFR under 35 mL/min/1.73 m2, and extend gentamicin intervals.