29 - Compartment Syndrome Flashcards
Objectives
- Compartmental anatomy of the lower extremity (foot and lower leg)
- Etiologies and pathophysiology of acute compartment syndrome
- Diagnosis and management of acute compartment syndrome
Anatomic compartments of the leg (Hayden system ***)
- Anterior
- Lateral
- Superficial posterior
- Deep posterior
Anterior leg
o Tibialis anterior
o Extensor halluces longus
o Extensor digitorum longus
o Peroneus tertius
Lateral leg
o Peroneus longus
o Peroneus brevis
Superficial posterior leg
o Soleus
o Gastrocnemius
o Plantaris
Deep posterior leg
o Tibialis posterior
o Flexor hallucis longus
o Flexor digitorum longus
Anatomic compartments of the foot (Myerson system ***)
NOTE: This is the BEST classification system so MEMORIZE THIS
- Central
- Medial
- Interosseous
- Lateral
Central foot
o Flexor digitorum brevis
o Lumbricals
o QP
o Adductor halluces
Medial foot
o Abductor halluces o Flexor halluces brevis o Flexor halluces longus tendon o Peroneus longus tendon o Posterior tibial tendon
Interosseous
o Interosseous muscles
Lateral foot
o Abductor digiti minimi
o Flexor digiti minimi
Flexor stabilization (STANCE PHASE – MOST COMMON)
o Seen with flexible pes valgus, STJ pronation and MTJ supination (unlocked)
o FDL and FDB fire earlier and longer in order to attempt to stabilize the foot
o The flexors therefore overpower the interosseous muscles
o FDL and FDB insert at the bases of the distal and middle phalanges
o During the stance phase of gait, the flexors plantarflex the digits, causing dorsiflexion at the MPJ (reverse buckling)
o Interosseous muscles insert on the base of the proximal phalanx – they act to plantarflex the MPJ during stance phase, which balances the reverse buckling of the flexors
o Can be due to weak QP, more medial pull of long flexors, medial abduction
Flexor substitution (SWING PHASE)
o Weak triceps surae
o Deep posterior and lateral groups attempt to “substitute” for the lack of plantarflexory force
o The flexors therefore fire earlier and longer and therefore overpower the interosseous muscles
o Least common type, seen in supinated feet and tends to appear as straight contracture of all lesser toes
Extensor substitution (SWING PHASE)
o EDL acts to dorsiflex the MPJ (via tightening of the extensor sling and extended the IPJs during swing
o Lumbricals act to plantarflex the MPJ while also extending the IPJs (via extensor wing)
o Flexors have a passive pull on toes during swing
o Lumbricals counteract the dorsiflexion caused by the passive pull of the flexors and the EDL during swing
o Starts as a flexible deformity that reduces completely during weight bearing, but may become rigid
Manoli and Weber – DO NOT MEMORIZE THIS
- Just another classification system
- Involves 9 compartments of the foot (one for each interossei muscle)
Clinical findings for acute compartment syndrome – KNOW FOR EXAM ***
- Recalcitrant pain
- Compartmental tenseness
- Sensory deficits following nerve distribution
- Motor deficits
- Pain on passive stretch
Compartmental pressure measurement – KNOW FOR EXAM ***
- Wick catheter
- Slit catheter
- Injection
- Infusion
- Stryker system
Compartment pressures – KNOW FOR EXAM ***
- Normal resting pressure: 0-8 mmHg
- Monitoring zone: 30-40 mmHg
- Pathologic pressure: 40 mmHg in the presence of clinical symptoms
Additional studies to consider doing ***
- ECG
- Urinalysis (routine and myoglobin analysis)
- Blood work (CBC with diff, electrolytes, BUN/creatinine, creatinine kinase)
Pathophysiology and causes of acute compartment syndrome ***
- Bleeding and interstitial edema occur after injury
- Compartmental interstitial pressures increase
- Increases local venous pressure
- Reduces local arteriovenous gradient
- Collapse of veins and loss of blood flow
- Results in microvascular compromise and myoneural damage
Causes of compartment syndrome ***
- Exertional
- Trauma ***
- Bleeding ***
- Burns
- Infiltration
- Major vascular injury
- Surgical closure ***
- External pressure
- Snake bites
- Infection
Study on surgical management ***
- Matsen reported 91% of extremities decompressed 12 hours after clinical onset had neuromuscular deficits
- Published principles of decompression
Principles of decompression
o Foot: dorsal vs plantar medial vs lateral vs combined approach
o Leg: parafibular vs two incisional approach
o Intraoperative pressures
o Avoid use of tourniquet
o Minimal debridement of muscle
o Greater than two compartments involved, decompress all compartments
Post-op management ***
- Monitor compartmental pressures
- Patman-Thompson technique
- Splinting
- Passive range of motion
- Delayed closure or grafting
