Chronic Exertional Compartment Syndrome

Chronic exertional compartment syndrome (CECS) is a reversible condition in which exercise raises pressure inside a closed muscle compartment beyond the level that supports blood flow. It causes recurrent pain, tightness and sometimes numbness that settle with rest. It is not an emergency, in contrast to acute compartment syndrome.

It is most frequent in runners, military recruits, cyclists and field athletes in their teens to thirties, and affects men and women equally. Most cases are in the anterior and deep posterior compartments of the lower leg (about 40% each), and less often in the lateral, superficial posterior, thigh, foot or forearm compartments. It is bilateral in 70 to 80% of cases.

It is a cause of exercise related leg pain, alongside medial tibial stress syndrome, stress fractures, popliteal artery entrapment and nerve entrapment. Complications are chronic limitation of exercise, nerve entrapment (the superficial peroneal nerve emerging through the lateral compartment fascia), muscle hernia, and, rarely, progression to acute compartment syndrome.

Pathophysiology.

During exercise, muscle volume increases by up to 20%. A noncompliant fascia, hypertrophied muscle, reduced venous outflow or thickened fascia causes a rise in pressure that exceeds the capillary perfusion pressure, which leads to relative ischaemia and pain. The pressure takes longer to normalise after exercise.

Typical history is a tight, cramping or aching pain in the leg that begins at a reproducible point of exercise (after a certain distance or time). It builds as exercise continues, forces the athlete to stop, and settles in 10 to 30 minutes of rest. Other symptoms are numbness and paraesthesia in the foot (deep posterior or superficial peroneal nerve involvement) and foot drop with severe anterior compartment pressure.

Examination at rest is usually normal. Examine after exercise for tense compartments, muscle herniae, tenderness, and sensory changes. Check pulses (before and after exercise, with ankle plantar flexion for popliteal artery entrapment), foot posture and running mechanics.

• The diagnosis is made from the typical history and confirmed by intracompartmental pressure measurement before and after exercise. Diagnostic criteria (Pedowitz): pre-exercise pressure of 15 mmHg or more, 1 minute post-exercise pressure of 30 mmHg or more, or 5 minute post-exercise pressure of 20 mmHg or more.
• Radiographs and MRI to exclude stress fracture, bone lesion and medial tibial stress syndrome. Bone scan if stress fracture is suspected.
• Dynamic MRI and near infrared spectroscopy (limited availability) support the diagnosis.
• Ankle brachial pressure index before and after exercise, and duplex ultrasound in plantar flexion for popliteal artery entrapment syndrome.
• Nerve conduction studies for nerve entrapment, and lumbar spine assessment.

Differential diagnosis.

• Medial tibial stress syndrome (shin splints) and tibial stress fracture.
• Popliteal artery entrapment syndrome and claudication.
• Superficial peroneal nerve or common peroneal nerve entrapment.
• Lumbar radiculopathy, tendinopathy and deep vein thrombosis.

Conservative treatment (3 to 6 months, success low at 20 to 30%).

• Activity modification: reduce running distance, change to low impact exercise (swimming, cycling), and soft surfaces.
• Gait retraining: switching from a heel strike to a forefoot strike pattern reduces the anterior compartment pressure.
• Orthoses for pes planus or pes cavus, stretching, soft tissue massage and strengthening. Footwear review.
• Botulinum toxin injection into the anterior and lateral compartments is used in some centres (an off label use that requires ultrasound direction and specialist care).

Surgery (failure of conservative treatment). Open or endoscopic fasciotomy of the affected compartments. Success rates are 80 to 90% for anterior and lateral compartments and lower (about 50 to 65%) for the deep posterior compartment. The deep posterior compartment is released through a medial incision and includes the tibial periosteal attachments of the fascia.

• Postoperative: early mobilisation with weight bearing as tolerated, calf and ankle exercises from day 1, return to walking at 2 weeks, light jogging at 4 weeks, and full sport at 6 to 12 weeks.
• Complications: haematoma, wound infection, nerve injury (superficial peroneal, saphenous), recurrence (from scarring or incomplete release) and lymphoedema.

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, vancomycin 15 mg/kg intravenously starting 90 to 120 minutes before incision as a single dose, with levels and creatinine checked in prolonged cases.

Analgesia.

• Paracetamol 1 g orally every 6 hours as needed for up to 5 to 7 days (maximum 4 g daily; 3 g daily when weight is under 50 kg, with chronic alcohol use or hepatic impairment).
• Ibuprofen 400 mg orally every 8 hours with food for up to 5 days (maximum 1200 mg daily); avoid with eGFR under 30 mL/min/1.73 m2, peptic ulcer, heart failure or anticoagulant use.
• Oral morphine 5 to 10 mg every 4 hours as needed for severe pain for up to 3 days (start 2.5 to 5 mg with age over 75 or eGFR under 30 mL/min/1.73 m2; avoid exceeding 60 mg in 24 hours without senior review). Monitor sedation and respiration and prescribe a laxative.

Monitoring. Symptoms with exercise, pain free distance and running mechanics at 6 weeks and 3 months. Wound, haematoma and nerve function at 2 weeks after surgery. Recurrence at 6 and 12 months, with repeat pressure testing if symptoms return.

Referral and escalation. Refer typical exertional leg pain that fails 3 months of conservative treatment to sports medicine or orthopaedics for pressure testing. Urgent referral for pain at rest, a tense swollen leg, severe numbness or foot drop (acute compartment syndrome), or reduced pulses.

Special groups.

• Athletes and military recruits: early diagnosis protects performance; surgery results are good for the anterior compartment.
• Women: equally affected; check for relative energy deficiency and stress fractures.
• Adolescents: assess growth and apophysitis before surgery.
• Kidney impairment: avoid ibuprofen and reduce morphine doses.