Well-Leg Compartment Syndrome

Well leg compartment syndrome is compartment syndrome in the contralateral (non-operative) leg, typically the leg placed in the lithotomy or hemilithotomy position for a long procedure (urological, colorectal, gynaecological, vascular), or on a leg support during lateral surgery.

Epidemiology. It is rare, with an estimated incidence of about 1 in 3,500 lithotomy procedures longer than 4 hours (some reports 1 in 8,700), and a mortality of up to 2% to 10% with limb loss in about 5%. About half need long term disability care.

Risk factors. Operative time over 4 hours, lithotomy with Trendelenburg, obesity, male sex, peripheral vascular disease, hypotension, vasopressors, muscular legs, concurrent leg compression sleeves, and leg height over heart level.

Pathophysiology.

Elevated legs reduce perfusion pressure at the calf, and leg support presses on the calf (compression). Reperfusion after lowering leads to oedema and raised compartment pressure.

Pain (calf or foot) out of proportion on waking or after ambulation, swollen tense calf, pain on passive dorsiflexion, numbness of the first web space (deep peroneal nerve) and weakness. Neuraxial block and opioids mask symptoms. Rhabdomyolysis and renal failure follow.

Red flags.

• Escalating pain or analgesic need after lithotomy.
• Tense, shiny calf.
• Foot drop or sensory loss.
• Dark urine.

Clinical diagnosis, supported by compartment pressure measurement (delta pressure under 30 mmHg or absolute pressure over 30 mmHg). Creatine kinase (over 1,000 units/L), potassium, creatinine, myoglobinuria and lactate. Do not rely on pulses.

Differential diagnosis.

• Deep vein thrombosis.
• Arterial occlusion.
• Cellulitis.
• Nerve compression (common peroneal).
• Block effect.
• Rhabdomyolysis without compartment syndrome.

Lower the leg to heart level, remove compression and call the surgical team. Perform emergency four compartment fasciotomy as soon as the diagnosis is made (ideally within 6 hours).

Rhabdomyolysis care:

• Crystalloid: 1 to 2 L IV in the first hour, then 200 to 300 mL/h to keep urine output 1 to 2 mL/kg/h; monitor creatine kinase, potassium, calcium, creatinine and urine pH; reduce in heart failure.
• Hyperkalaemia treatment: calcium chloride 10% 10 mL IV, insulin 10 units with 25 g glucose IV, salbutamol 10 to 20 mg nebulised; monitor ECG and glucose hourly.
• Haemodialysis or haemofiltration for refractory hyperkalaemia, acidosis or anuria.

Delayed wound closure at 48 to 72 hours, with rehabilitation. Disclose the event.

Prevention. Limit lithotomy time under 4 hours with release of legs every 2 hours in long procedures, avoid excessive head down tilt, use padded boots without calf compression, keep legs near heart level where possible, avoid hypotension, and monitor for symptoms in recovery and after epidural.

Monitoring. Limb examination every hour for 6 hours then every 4 hours for 24 to 48 hours, serial creatine kinase and renal function.

Referral and escalation. Orthopaedic or vascular surgery immediately; nephrology and critical care for renal failure.