Chronic Exertional Compartment Syndrome

The clinical pattern is the most important diagnostic clue. Patients describe tight, aching, cramping, or bursting pain in a specific compartment - the anterior compartment (anterolateral leg) most commonly. Symptoms are reproducibly exercise-induced: pain begins at a predictable time or distance, this reproducibility is the key discriminator. Symptoms worsen with continued activity and may force the athlete to stop, then resolve rapidly after stopping (typically within 5-30 minutes). Between episodes the patient is often completely asymptomatic, and symptoms recur reliably at the same point next session.

Neurological symptoms during exercise are common and follow the nerve within the affected compartment - anterior: first web space numbness, dorsiflexion weakness; lateral: dorsal foot numbness, eversion weakness; deep posterior: medial plantar numbness. These resolve after stopping. Bilateral symptoms are common. No symptoms at rest in typical CECS - rest pain should prompt consideration of other diagnoses.

Always ask about sport and training history, exact reproducibility of symptoms, bilateral involvement, anabolic steroid use, and previous leg surgery.

Examination at rest is often normal - a key teaching point. A normal resting examination does NOT exclude CECS. Palpate for fascial defects or herniation at rest - a soft tissue bulge at the junction of the middle and distal thirds of the anterolateral leg (where the superficial peroneal nerve perforates the fascia) is a strong clinical clue. Post-exercise examination (performed immediately after reproducing symptoms) is the most useful clinical assessment: the affected compartment may feel firm and tense, and neurological deficit may be demonstrable. Check distal pulses to assess for PAES and consider post-exercise ABPI if vascular pathology is suspected. Assess biomechanics: foot posture, ankle dorsiflexion, gait.

Differentials: MTSS (diffuse posteromedial tibial bone tenderness at rest), tibial stress fracture (focal bone point tenderness, progression to rest pain), PAES (exercise-induced calf pain with vascular features and ABPI drop on provocation), nerve entrapment (superficial peroneal at the fascial perforation, common peroneal at the fibular head), lumbar radiculopathy, and DVT.

The diagnosis is primarily clinical, supported by specialist testing where needed.

Intra-compartmental pressure (ICP) testing is the most widely used confirmatory test. The Pedowitz criteria are widely used: resting pressure 15 mmHg or more, OR 1-minute post-exercise pressure 30 mmHg or more, OR 5-minute post-exercise pressure 20 mmHg or more. Any one criterion met in a clinically symptomatic compartment supports the diagnosis. These thresholds have recognised limitations and a notable false-positive rate, so results should always be interpreted alongside clinical history. Many UK specialist centres are moving toward continuous dynamic ICP monitoring during treadmill exercise.

Dynamic MRI is increasingly used in some UK centres. Standard MRI is often normal at rest; dynamic MRI performed immediately after provocative exercise may show increased T2 signal in the affected compartment. Not yet universally available.

Near-infrared spectroscopy (NIRS) is an emerging non-invasive measurement of tissue oxygenation. Duplex USS or MR angiography with functional provocation is the standard pathway to exclude PAES, with post-exercise ABPI as the first-line objective vascular test. Plain radiographs and standard MRI do not diagnose CECS but exclude stress fracture, MTSS, and bone tumour. Bloods are not diagnostic; CK may be considered if rhabdomyolysis is a concern.

Management options are conservative (activity modification) or surgical (fasciotomy).

Conservative management is typically trialled for 3-6 months. Activity modification reduces or modifies the provocative activity, with switching to lower-impact activities to avoid provocation. Biomechanical optimisation addresses gait abnormalities and excessive pronation. Forefoot running patterns may reduce anterior compartment loading in selected runners - but transitioning from rearfoot to forefoot strike reduces anterior compartment pressure while increasing load on the posterior compartments, which must be considered when the posterior compartment is involved. Massage and stretching have limited evidence. Botulinum toxin injection has been reported in small studies, primarily for anterior and lateral compartments - not recommended for the deep posterior compartment due to complex anatomy and risk to deeper structures. Temporary effect (3-6 months), not standard first-line treatment.

Conservative management often plateaus at a fixed exercise threshold, which leads to consideration of fasciotomy.

Surgical management is subcutaneous fasciotomy of the affected compartment(s), the definitive treatment when conservative management has failed. Performed as a day-case procedure. Outcomes: anterior and lateral compartment fasciotomy generally has better reported outcomes than deep posterior release, which is technically more challenging due to fascial sub-compartmentalisation and produces less predictable results. Risks include haematoma, infection, nerve injury (particularly superficial peroneal during lateral compartment release), incomplete release, recurrence, and wound complications. Return to sport typically 6-12 weeks.

Refer to SEM specialist or orthopaedic surgeon with compartment-syndrome expertise for ICP testing, PAES exclusion, and surgical management. Do NOT delay referral for suspected acute compartment syndrome.

Conservative rehabilitation: activity modification to stay below the symptom threshold. Maintain fitness with non-provocative activities (cycling, swimming, aqua jogging). Address biomechanical contributors: calf strengthening, ankle dorsiflexion optimisation, hip and core strengthening. Gait retraining may be trialled for anterior compartment CECS in selected runners - but forefoot strike increases posterior compartment loading.

Post-fasciotomy rehabilitation:

• •Weeks 0-2: wound care, compression, weight-bearing as tolerated, gentle range-of-motion, ice and elevation, quadriceps and calf activation.
• •Weeks 2-4: progressive ROM, progressive weight-bearing, scar mobilisation, low-resistance cycling, progressive calf and lower-limb strengthening.
• •Weeks 4-8: progressive strengthening (single-leg calf raises, squats, lunges, step-ups), light jogging may be introduced (surgeon-dependent), continue cross-training.
• •Weeks 8-12: graduated return to running with a walk-run programme progressing to continuous running, sport-specific drills, progressive intensity.

Return to sport is typically 6-12 weeks and criteria-based: pain-free running at target distance and intensity, adequate lower-limb strength, and completion of the graduated programme.

If symptoms recur post-operatively, consider incomplete fascial release, a missed compartment, or alternative pathology (PAES, nerve entrapment).

• •Pedowitz et al. (1990, AJSM) - The Pedowitz ICP criteria (resting 15+, 1-min 30+, 5-min 20+ mmHg) remain the most widely used confirmatory test, though false-positive rates are recognised and clinical correlation is essential.
• •BJSM exercise-induced leg pain reviews - Reproducible time- or distance-dependent symptoms resolving within minutes of stopping are the most reliable diagnostic clue; standard MRI is usually normal between episodes.
• •Aweid et al. (2012, Clin J Sport Med) - Systematic review confirming fasciotomy of the anterior or lateral compartment has more predictable outcomes than deep posterior release.
• •NICE CKS: Leg pain - PAES must be excluded in any patient with exercise-induced calf pain and reduced pulses or claudication features; post-exercise ABPI is first-line.
• •IOC consensus on overuse injuries - Biomechanical and load modification first; surgery for symptoms that persist at a fixed exercise threshold despite 3-6 months of conservative care.

• •The reproducible exercise-induced pattern is the most important diagnostic clue: symptoms begin at a predictable time/distance, worsen with continued activity, resolve within minutes of stopping, and recur reliably.
• •Anterior compartment is the most commonly affected - deep peroneal nerve (first web space numbness, dorsiflexion weakness during symptoms).
• •Resting examination is often normal; a normal resting examination does not exclude CECS. Post-exercise examination is the most useful clinical assessment; check for fascial defects at rest.
• •Pedowitz ICP criteria: resting 15+, 1-min 30+, 5-min 20+ mmHg. Widely used but diagnostic validity is imperfect - interpret alongside clinical findings.
• •CECS is NOT acute compartment syndrome. CECS is chronic and reversible; acute compartment syndrome is a surgical emergency. MTSS has diffuse posteromedial tibial tenderness at rest; CECS typically has a normal resting examination.
• •Forefoot running may reduce anterior compartment loading but INCREASES posterior compartment loading - a classic exam trap. Deep posterior fasciotomy has less predictable outcomes than anterior or lateral release because the compartment is fascially subdivided.