Populations and Risk Factors
- Acute (ACS): Major trauma patients, crushing injuries, long bone fractures (especially tibial shaft), tight casts or circumferential dressings, burns, reperfusion after vascular surgery
- Chronic exertional (CECS): Runners, jumpers, athletes training on hard surfaces, military recruits
- Anterior compartment of the lower leg most commonly affected in both forms
- Males more commonly affected by CECS, likely due to greater muscle volume and higher-intensity training patterns
- Anticoagulant therapy increases bleeding risk into compartments after minor trauma
Causes and Pathophysiology
- Fascial anatomy: Muscles are enclosed within strong, inelastic fascial compartments (deep fascia of the leg has four: anterior, lateral, superficial posterior, deep posterior); these compartments have limited expansion capacity
- Pressure cascade (ACS): Tissue pressure rises above capillary perfusion pressure (typically > 30 mmHg) → blood cannot enter the compartment → ischemic cells release proinflammatory chemicals and free radicals → increased capillary permeability and further swelling → vicious cycle of rising pressure and decreasing perfusion
- Irreversible damage timeline: If pressure persists more than a few hours, permanent loss of muscle function and nerve damage occur; myonecrosis releases myoglobin and potassium into the circulation, risking acute kidney injury and cardiac arrhythmias
- CECS mechanism: Exercise increases muscle volume by up to 20%; in individuals with non-compliant fascia, this volume increase transiently raises compartment pressure above perfusion thresholds; symptoms resolve when exercise stops and muscle volume decreases
- Key distinction: ACS is caused by external force or internal bleeding raising pressure in a resting compartment; CECS is caused by normal exercise physiology in an anatomically tight compartment
Signs and Symptoms
Acute Compartment Syndrome ("6 Ps")
- Pain out of proportion to the apparent injury — the earliest and most reliable sign
- Paresthesia — numbness and tingling in the distribution of the nerves within the compartment (deep peroneal nerve in anterior compartment: web space between 1st and 2nd toes)
- Paresis/Paralysis — weakness progressing to inability to move (late sign)
- Pulselessness — loss of distal pulses (very late sign; absence does not rule out compartment syndrome)
- Pallor — pale, shiny, tense skin over the compartment
- Passive stretching of the muscles within the compartment is extremely painful
- Area feels hard and tense on palpation; rapid onset of numbness and paralysis
Chronic Exertional Compartment Syndrome
- Pain and cramping that begins during a specific activity and subsides completely when activity stops — this is the defining feature
- May involve tingling or numbness (not found in medial tibial stress syndrome / shin splints)
- Foot drop or "steppage gait" if the anterior compartment is involved (deep peroneal nerve compression)
- No symptoms at rest between episodes
Assessment Profile
Subjective Presentation
- Chief complaint: ACS: "My leg is killing me and the pain keeps getting worse even though I'm not moving it"; CECS: "My shins cramp up every time I run and the pain goes away when I stop"
- Pain quality: ACS: deep, unrelenting, burning, disproportionate to visible injury; CECS: aching, cramping, predictable with activity
- Onset: ACS: follows trauma, fracture, or tight cast; CECS: reproducible at a consistent point during exercise
- Aggravating factors: ACS: passive stretching of the compartment muscles, elevation (reduces arterial inflow); CECS: specific exercise intensity and duration
- Easing factors: ACS: nothing relieves the pain — this is a red flag; CECS: cessation of activity provides relief within minutes
- Red flags: ACS: pain out of proportion, paresthesia, hard tense compartment — emergency referral for fasciotomy; do NOT treat, do NOT apply PRICE
Observation
- Local inspection: ACS: tense, shiny skin; possible swelling over the compartment; CECS: compartment may appear swollen during exercise but normal at rest
- Posture: Not typically affected unless gait is compromised
- Gait: Foot drop (steppage gait) indicates deep peroneal nerve compression in the anterior compartment — present in both ACS and advanced CECS
Palpation
- Tone: ACS: compartment feels extremely hard and tense, "wooden" to palpation; CECS: increased firmness during symptomatic episodes, normal at rest
- Tenderness: ACS: diffuse tenderness over the entire compartment, not a single point; CECS: tenderness during and shortly after activity
- Temperature: ACS: may be warm from inflammation or cool distally from ischemia; CECS: normal
- Tissue quality: ACS: tissue feels board-like, unyielding; CECS: may feel swollen and tight during symptoms but returns to normal pliability at rest
Motion Assessment
- AROM: ACS: active dorsiflexion increases pain in anterior compartment (muscle contraction further increases compartmental pressure); CECS: pain reproduced with activity
- PROM / end-feel: ACS: passive plantar flexion (stretching the anterior compartment) produces intolerable, disproportionate pain — this is the key clinical test; CECS: normal passive range at rest
- Resisted testing: ACS: weakness of compartment muscles (late sign); CECS: may show weakness during symptomatic episodes
Special Test Cluster
| Test | Positive Finding | Purpose |
|---|---|---|
| Passive stretch test (CMTO) | Passive stretching of compartment muscles produces deep, burning, disproportionate pain | Confirm — positive in ACS is a surgical emergency |
| Sensation map — web space (CMTO) | Loss of sensation between 1st and 2nd toes | Confirm deep peroneal nerve compression (anterior compartment) |
| Distal pulse check (CMTO) | Diminished or absent dorsalis pedis pulse | Red flag screen — late sign; do not wait for pulse loss to refer |
| Compartment pressure measurement (supplementary — medical) | > 30 mmHg at rest or within 30 mmHg of diastolic pressure | Confirm — gold standard medical test; MT uses clinical signs for referral |
ACS can occur in any fascial compartment. If symptoms involve the forearm after supracondylar fracture, apply the same assessment principles to the forearm compartments.
Differential Assessment
| Condition | Key Distinguishing Feature |
|---|---|
| Medial tibial stress syndrome (shin splints) | Diffuse tenderness along medial tibial border; no numbness or tingling; pain resolves with rest |
| Stress fracture | Focal point tenderness on bone; positive percussion test; no compartment tension |
| Deep vein thrombosis | Calf swelling, warmth, positive Homan sign; no compartment tension or nerve symptoms |
| Peripheral artery disease | Claudication pattern; absent pulses at rest; older population |
CMTO Exam Relevance
- CMTO Appendix category A1 (MSK conditions)
- Red flag condition: ACS requires immediate ER referral for fasciotomy
- Key differential: compartment syndrome vs. shin splints (numbness/tingling suggests compartment syndrome, not shin splints)
- The "6 Ps" are high-yield exam content — know them in order of appearance (pain → paresthesia → paresis → paralysis → pulselessness → pallor)
- Understand that PRICE protocol is contraindicated in ACS because compression, ice, and elevation further reduce perfusion to an already ischemic compartment
Massage Therapy Considerations
- Primary therapeutic target: CECS only — reduce fascial restriction and muscle tension in the affected compartment to improve compliance and reduce transient pressure buildup during exercise
- Sequencing logic: For CECS, treat only when the client is asymptomatic (not during or immediately after an episode); begin with general lower leg circulation, then specific fascial work to the compartment boundaries
- Safety / contraindications: ACS is an immediate ER referral for fasciotomy — do NOT treat; never use compression, ice, or elevation (PRICE) for suspected ACS as these further reduce already compromised circulation; any client with unrelenting leg pain, numbness, and a hard compartment must be sent to the emergency department immediately
- Heat/cold guidance: For CECS between episodes, moist heat pre-treatment to improve fascial pliability; cold post-treatment to reduce any reactive inflammation; for ACS, no hydrotherapy — refer immediately
Treatment Plan Foundation
Clinical Goals
- Reduce fascial restriction in the affected compartment to improve exercise tolerance (CECS)
- Decrease hypertonicity in compartment muscles that contribute to pressure buildup
- Restore normal lower leg biomechanics that may be contributing to compartment overload
Position
- Supine with knee slightly flexed for anterior and lateral compartment access
- Prone for posterior compartment access
Session Sequence
- General effleurage to the entire lower leg to assess tissue state and encourage circulation
- Broad petrissage to the gastrocnemius-soleus complex to reduce posterior compartment tension
- Myofascial release along the anterior compartment fascial boundaries — slow, sustained pressure following tissue response
- Deep longitudinal stripping along the tibialis anterior and extensor digitorum longus within the anterior compartment
- Sweeping cross-fiber strokes across the compartment to encourage fascial mobility and fluid movement
- Peroneal compartment work — effleurage and gentle stripping of the peroneus longus and brevis if the lateral compartment is involved
- Reassessment of tissue firmness and AROM
Adjunct Modalities
- Hydrotherapy: Moist heat pre-treatment (15 min) to improve fascial pliability; cold pack post-treatment (10 min) over the treated compartment
- Remedial exercise (on-table): Active dorsiflexion-plantarflexion pumping to encourage compartment fluid movement; gentle calf stretching (gastrocnemius and soleus) to reduce posterior chain contribution to anterior compartment pressure
Exam Station Notes
- Demonstrate the ability to differentiate ACS from CECS using history and clinical signs
- If the scenario describes ACS, the correct action is referral, not treatment
- Show the passive stretch test and explain its significance
- Demonstrate bilateral comparison of compartment firmness
Self-Care
- Gradual training progression (10% rule) to prevent CECS flare-ups
- Self-massage with a foam roller along the anterior and lateral compartments after training
- Proper footwear assessment and consideration of orthotic support for biomechanical contributors
- Activity modification: running on softer surfaces, reducing impact intensity
Key Takeaways
- Acute compartment syndrome (ACS) is an immediate ER referral for fasciotomy; do NOT treat, and never apply compression, ice, or elevation (PRICE), as these further reduce already compromised circulation
- The "6 Ps" of ACS are high-yield: Pain out of proportion, Paresthesia, Pulselessness, Paresis, Paralysis, Pallor
- If a client reports numbness or tingling with leg pain, suspect compartment syndrome over shin splints
- For chronic exertional compartment syndrome (CECS), avoid soft-tissue manipulation while symptoms are active; once subsided, use broad longitudinal gliding and sweeping cross-fiber strokes
- Permanent tissue necrosis and loss of function can occur if ACS pressure persists more than a few hours
- Passive stretch of the compartment muscles producing disproportionate pain is the key clinical sign of ACS