High Yield Overview
CHRONIC EXERTIONAL COMPARTMENT SYNDROME
Exercise-Induced | ICP Measurement | Fasciotomy | Athletes
30mmHgDiagnostic threshold at 1 min post
15mmHgResting pressure threshold
95%Return to sport after fasciotomy
Bilateral85% bilateral cases
LEG COMPARTMENTS AFFECTED
Anterior
PatternMost common (45%)
TreatmentRelease anterior compartment
Lateral
PatternCommon (35%)
TreatmentRelease lateral compartment
Deep Posterior
PatternLess common (15%)
TreatmentRelease deep posterior
Superficial Posterior
PatternRare (5%)
TreatmentRelease superficial posterior
Critical Must-Knows
- Aching pain during exercise that resolves with rest - distinguishes from acute compartment syndrome
- ICP measurement is gold standard - pre-exercise, 1 min post, 5 min post
- Diagnostic thresholds: over 15mmHg rest, over 30mmHg at 1 min, over 20mmHg at 5 min
- Fasciotomy is definitive treatment - excellent outcomes in most
- Rule out other causes: stress fracture, MTSS, popliteal entrapment, nerve entrapment
Examiner's Pearls
- "Anterior compartment most common (45%), often with lateral (35%)
- "Symptoms reproducible with specific exercise intensity and duration
- "Neurological symptoms (paresthesias, foot drop) often present
- "Bilateral in 85% - if unilateral, reconsider diagnosis
Clinical Imaging
Imaging Gallery
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Clinical Imaging
Leg Compartment Anatomy
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ICP Measurement Technique
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Critical CECS Points for Exams
Distinguish from Acute
CECS: Aching during exercise, relieved by rest, reproducible, no tissue necrosis risk. Acute CS: Severe pain at rest, progressive, emergency, tissue death imminent.
ICP Thresholds
Pedowitz criteria: Resting over 15mmHg OR 1 min post over 30mmHg OR 5 min post over 20mmHg. Any ONE criterion positive = diagnostic.
Bilateral Pattern
85% are bilateral - if truly unilateral, strongly reconsider differential diagnosis. May need to measure and release both legs.
Exclude Other Causes
Must rule out: stress fracture (bone scan), MTSS (diffuse pain), popliteal artery entrapment (ABI), nerve entrapment (EMG), vascular claudication.
At a Glance: Quick Decision Guide
| Scenario | Key Finding | Action |
|---|---|---|
| Athlete with exercise leg pain, resolves with rest | Reproducible, tight compartments | ICP measurement pre/post exercise |
| ICP meets Pedowitz criteria | Over 30mmHg at 1 min post | Diagnose CECS, consider fasciotomy |
| Point tenderness over tibia | Positive bone scan | Think stress fracture, not CECS |
| Unilateral symptoms only | Single leg affected | Reconsider diagnosis, exclude other causes |
| Foot drop with exercise | Anterior compartment CECS | Indicates nerve involvement, needs release |
| Conservative treatment failed | Activity modification, orthotics failed | Proceed to fasciotomy |
Mnemonic
15-30-20ICP Measurement Thresholds
15
Resting
Pre-exercise threshold over 15mmHg
30
1 minute post
Immediately post-exercise over 30mmHg
20
5 minutes post
At 5 min post-exercise over 20mmHg
Memory Hook:15-30-20: The Pedowitz criteria numbers in sequence!
Mnemonic
ALDSLeg Compartments
A
Anterior
Most common (45%) - TA, EHL, EDL, peroneal nerve
L
Lateral
Second most (35%) - peroneals, superficial peroneal nerve
D
Deep posterior
Less common (15%) - TP, FHL, FDL, tibial nerve
S
Superficial posterior
Rare (5%) - gastroc, soleus, sural nerve
Memory Hook:ALDS compartments - Anterior and Lateral most common in CECS!
Mnemonic
ACHINGSymptoms Pattern
A
Aching pain
Dull ache during exercise
C
Consistent trigger
Same activity/duration triggers symptoms
H
Heaviness/tightness
Feeling of swollen, tight compartment
I
Improving with rest
Resolves within minutes of stopping
N
Neurological symptoms
Paresthesias, foot drop
G
Getting worse
Progressive with continued activity
Memory Hook:ACHING during exercise that gets better with rest = CECS pattern!
Mnemonic
STAMPSDifferential Diagnosis
S
Stress fracture
Point tenderness, positive bone scan
T
Tibial nerve entrapment
Tarsal tunnel syndrome
A
Artery entrapment
Popliteal artery entrapment syndrome
M
MTSS
Medial tibial stress syndrome (shin splints)
P
Peroneal nerve
Common peroneal entrapment at fibular neck
S
Superficial vein
Venous claudication
Memory Hook:STAMPS out the differential diagnosis for exercise leg pain!
Overview and Epidemiology
What is CECS?
Chronic Exertional Compartment Syndrome (CECS) is a condition where:
- Exercise induces elevated intracompartmental pressure
- Muscles swell within non-compliant fascial boundaries
- Blood flow is impaired during activity
- Symptoms develop predictably with specific exercise
- Symptoms resolve with rest (no tissue necrosis)
Key Distinction from Acute CS
CECS: Reversible, chronic, no tissue necrosis, not an emergency
Acute CS: Progressive, irreversible without treatment, tissue death, EMERGENCY
Anatomy and Compartments
Leg Compartment Anatomy
Leg Compartments
| Compartment | Contents | Nerve | Function Lost if Affected |
|---|---|---|---|
| Anterior | TA, EHL, EDL, peroneus tertius | Deep peroneal | Dorsiflexion, toe extension |
| Lateral | Peroneus longus and brevis | Superficial peroneal | Eversion, sensory first web |
| Deep Posterior | TP, FHL, FDL, popliteus | Tibial nerve | Toe flexion, inversion |
| Superficial Posterior | Gastrocnemius, soleus, plantaris | Sural nerve (sensory) | Plantarflexion |
Pathophysiology
The Pressure-Ischemia Cycle
CECS develops through a predictable sequence of events during exercise:
Step 1: Muscle Expansion
- Exercise increases muscle blood flow by up to 10-fold
- Active muscle volume increases by 20% due to hyperemia
- Metabolic demands require increased tissue perfusion
Step 2: Fascial Constraint
- The fascia surrounding leg compartments is non-compliant
- Cannot stretch to accommodate increased muscle volume
- Creates a closed space with rising pressure
Step 3: Pressure Rise
- Normal resting pressure: 8-10 mmHg
- Exercise increases pressure to 30-80+ mmHg in CECS patients
- Critical threshold: when pressure exceeds capillary perfusion pressure
Step 4: Ischemia
- Elevated tissue pressure compresses capillaries
- Arterial inflow maintained but venous outflow impaired
- Relative tissue ischemia develops
- Pain and neurological symptoms ensue
Step 5: Recovery
- Cessation of exercise reduces metabolic demand
- Muscle volume decreases over 10-15 minutes
- Pressure normalizes and symptoms resolve
- No permanent tissue damage (unlike acute compartment syndrome)
Why Anterior Compartment Most Common
The anterior compartment is affected in 45% of CECS cases because:
- It has the smallest fascial envelope relative to muscle mass
- Contains muscles with high activity during running (tibialis anterior)
- Experiences the greatest percentage volume change with exercise
- Less fascial compliance than other compartments
Classification Systems
Compartment-Based Classification
CECS by Compartment Location
| Type | Frequency | Key Features | Nerve at Risk |
|---|---|---|---|
| Anterior CECS | 45% | Most common, dorsiflexion weakness | Deep peroneal |
| Lateral CECS | 35% | Often combined with anterior | Superficial peroneal |
| Deep Posterior CECS | 15% | Medial symptoms, harder to diagnose | Tibial nerve |
| Superficial Posterior CECS | 5% | Rare, calf cramping | Sural nerve |
| Combined CECS | 60%+ | Multiple compartments involved | Multiple nerves |
Clinical Pearl
Anterior and lateral compartments are often affected together. When releasing one, always assess the other. Over 60% of patients have multiple compartment involvement.
History
History Taking
Classic Presentation:
- Aching, cramping pain with exercise
- Develops after predictable duration/intensity
- Relieved within minutes of rest
- Bilateral in 85% of cases
Key Questions:
- "How long into exercise does pain start?"
- "How quickly does it resolve with rest?"
- "Is it the same every time?"
- "Any numbness or tingling?"
- "Any weakness (foot drop)?"
Red Flags (Not CECS):
- Pain at rest
- Pain that doesn't resolve with rest
- Point tenderness (stress fracture)
- Night pain
Proper technique and attention to detail ensure optimal outcomes.
Examination
Physical Examination
At Rest (Usually Normal):
- Compartments soft
- Normal neurology
- No tenderness typically
Immediately Post-Exercise:
- Compartment tightness/firmness
- May have temporary neurological deficit
- Muscle herniation possible through fascial defects
- Symptoms reproducible
Neurovascular Exam:
- Assess motor function per compartment
- Sensory assessment (first web space = deep peroneal)
- Pulses (usually normal, but check)
Proper technique and attention to detail ensure optimal outcomes.
Investigations
Intracompartmental Pressure Testing
Gold Standard for Diagnosis
Technique:
- Slit catheter or Stryker needle
- Measure at rest (pre-exercise)
- Measure at 1 minute post-exercise
- Measure at 5 minutes post-exercise
- Insert perpendicular to leg, into compartment bulk
Pedowitz Diagnostic Criteria
| Timing | Threshold | Interpretation |
|---|---|---|
| Pre-exercise (resting) | Over 15 mmHg | Positive |
| 1 minute post-exercise | Over 30 mmHg | Positive |
| 5 minutes post-exercise | Over 20 mmHg | Positive |
Interpretation
Any ONE criterion positive = diagnostic for CECS. Most helpful is the 1 minute post-exercise reading - should be elevated significantly above baseline.
Differential Diagnosis
Differential Diagnosis Comparison
| Condition | Key Feature | Investigation | Distinguishing Factor |
|---|---|---|---|
| Stress fracture | Point tenderness | MRI or bone scan | Focal pain, positive imaging |
| MTSS (shin splints) | Diffuse medial tibial pain | Bone scan (diffuse) | Longer recovery, not exercise-limited |
| Popliteal artery entrapment | Claudication with exercise | ABI post-exercise, angio | Reduced pulses, vascular symptoms |
| Deep vein thrombosis | Calf swelling, tenderness | Duplex ultrasound | Constant symptoms, swelling |
| Nerve entrapment | Neurological symptoms dominant | EMG/NCS | Specific nerve distribution |
| Muscle strain | Acute onset | Clinical, possibly MRI | History of specific injury |
Key Differentiating Factor
CECS: Predictable, reproducible, exercise-induced, resolves with rest
Other conditions: May have pain at rest, variable patterns, don't follow exercise intensity reliably
Management
📊 Management Algorithm
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Non-Operative Management
First-Line Options (May help but often fail):
- Activity modification (reduce intensity/duration)
- Gait retraining (forefoot vs heel strike)
- Stretching and massage
- Orthotics (theoretical benefit)
- Cross-training (swimming, cycling)
- NSAIDs (limited evidence)
Success Rate:
- Low for return to full activity (under 50%)
- May be adequate if willing to modify sport
- Athletes usually require surgery
Conservative Trial
Conservative management should be tried first, but in dedicated athletes with confirmed CECS, fasciotomy is usually needed for return to sport.
Surgical Technique
Anterior Compartment Fasciotomy
Positioning:
- Supine with leg externally rotated
- Tourniquet optional (many prefer no tourniquet)
- Pad bony prominences
Approach:
- Single lateral incision, 2-3cm anterior to fibula
- Length: 10-15cm for adequate release
- Identify subcutaneous fat and crural fascia
Fasciotomy:
- Incise anterior compartment fascia longitudinally
- Extend proximally and distally with scissors
- Release must be complete from tibial plateau to ankle
- Visualize muscle bulging through fasciotomy
Key Points:
- Ensure complete release
- Identify anterior intermuscular septum
- Check lateral compartment if symptomatic
Proper technique ensures adequate decompression.
Complications
Intraoperative Complications
Intraoperative Risks
| Complication | Risk | Prevention | Management |
|---|---|---|---|
| Superficial peroneal nerve injury | Most common nerve injury | Identify and protect | Observation if neuropraxia |
| Incomplete release | Commonest cause of failure | Full visualization | Revision surgery |
| Vascular injury | Rare | Know anatomy | Direct repair or ligation |
| Wrong compartment | Rare | Confirm anatomy | Release correct compartment |
Nerve Injury
Superficial peroneal nerve injury during lateral release is the most common nerve complication. It causes numbness over the dorsum of the foot but does not affect motor function. Most are neuropraxias that recover.
Complication Summary
| Complication | Incidence | Risk Factor |
|---|---|---|
| Recurrence | 5-10% | Incomplete release |
| Wound complications | 3-5% | Hematoma, poor technique |
| Nerve injury | 1-3% | Superficial peroneal at risk |
| DVT | Under 1% | Immobility |
| Infection | 1-2% | Standard surgical risk |
Postoperative Care
Immediate Postoperative (0-2 weeks)
Day of Surgery:
- Compression dressing
- Elevate leg
- Ankle ROM exercises begin same day
- Weight-bearing as tolerated
First 2 Weeks:
- Wound checks at 5-7 days
- Remove sutures at 10-14 days
- Active ankle dorsiflexion/plantarflexion
- Ice for swelling
- Gentle calf stretches
Goals:
- Wound healing
- Maintain ankle ROM
- Control swelling
- Prevent DVT
Early mobilization is key to successful recovery.
Outcomes and Prognosis
Surgical Results
Fasciotomy Outcomes
| Outcome | Rate | Notes |
|---|---|---|
| Return to sport | 90-95% | Most return to pre-injury level |
| Patient satisfaction | 85-95% | High satisfaction rates |
| Recurrence rate | 5-10% | Usually due to inadequate release |
| Complication rate | Under 5% | Wound and nerve issues rare |
Prognostic Factors
Favorable
- Clear diagnosis (positive ICP)
- Anterior/lateral compartment
- Complete surgical release
- Younger patients
- Single sport athlete
Less Favorable
- Atypical presentation
- Deep posterior involvement
- Previous failed surgery
- Military personnel (higher demands)
- Coexisting conditions
Evidence Base
Pedowitz Diagnostic Criteria
Pedowitz RA, Hargens AR, Mubarak SJ, Gershuni DH • Am J Sports Med (1990)
Key Findings:
- Established the diagnostic thresholds for CECS: pre-exercise over 15mmHg, 1 minute post over 30mmHg, or 5 minutes post over 20mmHg. Any one positive is diagnostic.
Clinical Implication: These criteria remain the gold standard for diagnosing CECS. ICP measurement is essential for confirming the diagnosis before surgical intervention.
Fasciotomy Outcomes Meta-Analysis
Winkes MB, Hoogeveen AR, de Bie RA • Am J Sports Med (2012)
Key Findings:
- Meta-analysis of fasciotomy outcomes showed 84-95% successful return to sport. Success rates higher for anterior/lateral compared to deep posterior release.
Clinical Implication: Fasciotomy is highly effective for CECS. Anterior and lateral releases have the best outcomes. Deep posterior syndrome is more challenging.
Bilateral Involvement
Blackman PG, Simmons LR, Crossley KM • Br J Sports Med (1998)
Key Findings:
- Bilateral involvement in 85-95% of CECS cases. Unilateral presentation should prompt reconsideration of diagnosis and investigation of other causes.
Clinical Implication: Bilateral symptoms are the norm. Consider alternative diagnosis if presentation is truly unilateral. May need to measure and release both legs.
Conservative vs Surgical Management
Micheli LJ, Solomon R, Solomon J, et al • Clin J Sport Med (1999)
Key Findings:
- Conservative management success rate is low (under 50%) for athletes wanting to return to full sport. Fasciotomy provides reliable return to activity for most patients.
Clinical Implication: While conservative management should be tried first, most athletes with confirmed CECS require surgical release for return to sport.
Deep Posterior Compartment Syndrome
Schepsis AA, Gill SS, Foster TA • Am J Sports Med (1993)
Key Findings:
- Deep posterior CECS is often underdiagnosed and has lower success rates with surgery compared to anterior/lateral. The soleal bridge must be released for complete decompression.
Clinical Implication: Be aware of deep posterior involvement, especially with medial symptoms. Release soleal bridge for adequate decompression.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
Classic CECS Presentation
EXAMINER
"A 22-year-old long-distance runner presents with bilateral anterior leg pain that starts 20 minutes into running and forces her to stop. Pain resolves within 5-10 minutes of rest. She describes tightness and occasional numbness on the dorsum of her foot. Examination at rest is normal."
EXCEPTIONAL ANSWER
This is a classic presentation of chronic exertional compartment syndrome (CECS). The key features are: bilateral presentation (85% are bilateral), exercise-induced symptoms with a consistent trigger point (20 minutes), rapid resolution with rest, and neurological symptoms (numbness in deep peroneal nerve distribution). The anterior compartment is most commonly affected (45%). My approach would be: First, examine immediately post-exercise to feel the compartment tightness and assess for neurological changes. I would then arrange intracompartmental pressure measurement using the Pedowitz criteria: measure at rest, 1 minute post-exercise, and 5 minutes post-exercise. Diagnostic thresholds are: resting over 15mmHg, 1 minute post over 30mmHg, or 5 minutes post over 20mmHg. I would also obtain X-rays to rule out stress fracture and consider MRI if diagnosis unclear. If CECS is confirmed and conservative management fails (activity modification, gait retraining), I would recommend fasciotomy of the anterior compartment bilaterally. This has over 90% success rate for return to sport.
KEY POINTS TO SCORE
Recognize classic CECS pattern
Bilateral involvement is typical (85%)
Pedowitz criteria for diagnosis
Anterior compartment most common
Fasciotomy is definitive treatment
COMMON TRAPS
✗Missing the diagnosis by not measuring ICP
✗Not recognizing bilateral pattern
✗Confusing with acute compartment syndrome
✗Not ruling out stress fracture
LIKELY FOLLOW-UPS
"What are the Pedowitz criteria numbers?"
"How do you perform ICP measurement?"
"What surgical approach would you use?"
VIVA SCENARIOChallenging
Unilateral Presentation
EXAMINER
"A 28-year-old male soccer player presents with unilateral right leg pain with exercise. He describes cramping in the calf that starts after 30 minutes of training. He has no numbness. His pain sometimes persists for hours after stopping."
EXCEPTIONAL ANSWER
This presentation raises red flags for CECS. While the exercise-induced nature is consistent, there are atypical features: unilateral presentation (CECS is bilateral in 85%), calf location (superficial posterior is rare at 5%), and prolonged symptoms after stopping (CECS typically resolves within minutes). My differential diagnosis would include: stress fracture (but usually more point tender), popliteal artery entrapment syndrome (PAES - claudication pattern), medial tibial stress syndrome, deep vein thrombosis, or nerve entrapment. I would investigate with: careful examination for point tenderness, ankle-brachial index at rest and post-exercise (if reduced, suggests PAES), X-ray and possibly MRI/bone scan for stress fracture, and Doppler ultrasound if DVT suspected. If I still suspect CECS, I would perform ICP measurement. However, with atypical features, other diagnoses are more likely. If PAES is diagnosed, management is surgical release of the popliteal artery; if stress fracture, protected weight-bearing and activity modification.
KEY POINTS TO SCORE
Recognize atypical features
Unilateral presentation should prompt reconsideration
Consider popliteal artery entrapment syndrome
Prolonged symptoms atypical for CECS
Broad differential needed
COMMON TRAPS
✗Assuming CECS without considering alternatives
✗Missing popliteal artery entrapment
✗Not investigating unilateral pattern further
LIKELY FOLLOW-UPS
"How do you diagnose popliteal artery entrapment?"
"What if ABI drops post-exercise?"
"How would you manage PAES?"
VIVA SCENARIOCritical
Failed Fasciotomy
EXAMINER
"A 25-year-old triathlete had anterior compartment fasciotomy for CECS 6 months ago. She has returned to training but symptoms have recurred. ICP measurement shows elevated pressures in the anterior compartment."
EXCEPTIONAL ANSWER
This represents recurrent CECS after fasciotomy, which occurs in 5-10% of cases. The most common cause is incomplete fascial release at the initial surgery. My approach: First, confirm the diagnosis with repeat ICP measurement (which has been done and shows elevated pressures). Review the operative note from the first surgery - was the release truly complete from proximal to distal? Was the lateral compartment also assessed? Consider whether there is involvement of additional compartments not addressed initially, particularly the lateral compartment which is often affected with anterior (35% of cases). Examination post-exercise should assess all compartments. Management would be revision fasciotomy. Key principles: ensure complete release of the anterior compartment fascia from the tibial plateau to the anterior ankle, consider releasing the lateral compartment if not previously done, use a more extensile approach if needed, and consider the role of scar tissue requiring excision. I would counsel the patient that revision surgery has slightly lower success rates than primary surgery but is still worthwhile. Following revision, same rehabilitation protocol applies.
KEY POINTS TO SCORE
Recurrence usually due to incomplete release
Confirm with repeat ICP measurement
Consider additional compartments involved
Review original operative findings
Revision fasciotomy indicated
COMMON TRAPS
✗Not investigating the cause of failure
✗Assuming nothing more can be done
✗Missing lateral compartment involvement
LIKELY FOLLOW-UPS
"What is the most common cause of recurrence?"
"How would your approach differ at revision?"
"What if all compartments have been released?"
MCQ Practice Points
ICP Criteria Question
Q: What are the Pedowitz criteria for diagnosing CECS?
A: 15-30-20: Pre-exercise over 15mmHg, 1 min post over 30mmHg, 5 min post over 20mmHg. Any ONE positive is diagnostic.
Compartment Question
Q: Which compartment is most commonly affected in CECS?
A: Anterior compartment (45%), followed by lateral (35%), deep posterior (15%), and superficial posterior (5%). Anterior and lateral are often affected together.
Bilateral Question
Q: What percentage of CECS cases are bilateral?
A: 85% are bilateral. If truly unilateral, strongly reconsider the diagnosis and investigate other causes such as popliteal artery entrapment or stress fracture.
Nerve Question
Q: What nerve is at risk during lateral compartment release for CECS?
A: The superficial peroneal nerve emerges through the lateral compartment and is at risk during fasciotomy. It must be identified and protected.
Return to Sport Question
Q: What is the expected return to sport rate after fasciotomy for CECS?
A: 90-95% of patients return to their previous level of sport after fasciotomy. Success is highest for anterior and lateral compartment releases.
Australian Context
Sports Medicine Setting
- Common in elite athletes (AFL, athletics)
- Sports medicine physicians often first contact
- Multidisciplinary approach with physio
- Return to play decisions important
Investigation Access
- ICP measurement at tertiary sports centers
- MRI widely available
- Vascular studies if PAES suspected
- Bone scan for stress fracture exclusion
Medicare Funding
Fasciotomy of leg procedures covered under Medicare. Multiple compartment releases may need separate items. Private health insurance covers most surgical costs.
Consent Points
95% return to sport expectation. 5-10% recurrence rate. Nerve injury risk (superficial peroneal). Wound complications possible. May need bilateral surgery.
CHRONIC EXERTIONAL COMPARTMENT SYNDROME
High-Yield Exam Summary
Definition
- •Exercise-induced elevated intracompartmental pressure
- •Symptoms with exercise, resolve with rest
- •Reversible, no tissue necrosis (unlike acute CS)
- •85% bilateral
Pedowitz Criteria (15-30-20)
- •Resting (pre-exercise) over 15mmHg
- •1 minute post-exercise over 30mmHg
- •5 minutes post-exercise over 20mmHg
- •Any ONE positive = diagnostic
Compartment Frequency
- •Anterior: 45% (most common)
- •Lateral: 35% (often with anterior)
- •Deep posterior: 15%
- •Superficial posterior: 5% (rare)
Treatment
- •Conservative: Usually fails in athletes
- •Fasciotomy: Definitive treatment
- •95% return to sport post-op
- •Complete release essential
Differential (STAMPS)
- •Stress fracture - point tenderness
- •Tibial nerve entrapment
- •Artery entrapment (popliteal)
- •MTSS (shin splints)
- •Peroneal nerve entrapment
Surgical Pearls
- •Protect superficial peroneal nerve
- •Complete release proximal to distal
- •Consider releasing lateral with anterior
- •Soleal bridge for deep posterior