Acute Compartment Syndrome

• Occurs when increased pressure within a compartment compromises circulation and tissue function, leading to neuromuscular ischemia and potentially irreversible neuromuscular deficits.
• Muscle groups of the extremities are divided into sections or compartments, which are held together by fascial membranes.

Anatomic Compartments

• Leg compartments include superficial posterior, anterior, lateral, and deep posterior.
• Forearm compartments include anterior, posterior, and lateral.
• Other locations include hand (interosseous compartment), upper arm, foot, gluteal region, and abdomen.
• It can occur anywhere in the body where skeletal muscle is surrounded by fascia and bone.
• 80% of cases occur within the leg, most commonly in the anterior compartment of the lower leg.

Acute Compartment Syndrome Pathogenesis

• Intracompartmental pressure (within the enclosed fascia/bone) has a fixed volume.
• As compartment pressure rises, venous outflow is reduced, leading to a rise in venous pressure and a decrease in the arteriovenous pressure gradient.
• Eventually, the blood is shunted away from intra-compartmental tissues due to insufficient arteriolar pressure to overcome compartment pressure.
• Capillaries collapse, reducing oxygen supply to the muscles.
• Decreased oxygen (hypoxia) triggers the release of vasoactive substances.
• Serotonin and histamine, allow capillaries to release more fluid into the already tight compartment.

Ischemia

• Nerve Ischemia:
  • Normal conduction can continue for 1 hour
  • Reversible damage lasts 1-4 hours
  • Irreversible damage can occur after 8 hours
• Muscle Ischemia:
  • Reversible damage can last for 4 hours
  • Damage can be variable for 4-8 hours
  • Irreversible damage can occur after 8 hours

Etiology

• Trauma:
  • Fractures, particularly of long bones in the lower leg or forearm, account for 75% of the cases
  • Penetrating or minor trauma
• Nontraumatic Causes:
  • Ischemia-reperfusion injury
  • Coagulopathy
  • Animal envenomation and bites
  • Extravasation of IV fluids
  • IV drug use
  • Prolonged limb compression
  • Burns

Symptoms

• Pain that is disproportionate to the observed injury, often described as deep, throbbing, burning, or tightness.
• Paresthesia secondary to nerve ischemia.

Signs

• Classic signs (5 P's) are not reliable:
  • Pain
  • Pallor
  • Paralysis
  • Pulselessness
  • Paresthesia

Physical Examination

• Pain during passive stretching of muscles in the compartment (early sign).
• Tense compartment
• Decreased light touch and two-point discrimination.
• Weakness of muscles in the compartment.
• Paralysis (late sign), where sensory nerves are affected before motor nerves.

Diagnosis

• Based on clinical findings.
• Measurement of compartment pressures.
• Lab values are not necessary.
• Treatment should not be delayed if obtained.
• Radiographs should be taken to assess for fractures.

Measurement Techniques

• Stryker Device is the most common
• Simple Needle Manometer System
• The Wick
• Slit Catheter Technique

Tissue Pressure

• Normal tissue pressure is 0-8 mm Hg.
• Indications for Fasciotomy:
  • Absolute Pressure Theory: tissue pressure >30-45mm Hg, may lead to unnecessary fasciotomies.
  • Pressure Gradient Theory: tissue pressure within 20 mm Hg of Diastolic Blood Pressure, pressure necessary for injury varies depending upon clinical circumstances (HTN vs Normo/Hypotensive).

Treatment

• Remove any dressing, splint, cast, or other restrictive coverings
• Do not raise or lower the extremity, keep it at heart level
• Maintain hydration and urine output
• Analgesics
• Hyperbaric Oxygen
• Serial exams
• Decompress compartments if indicated

Fasciotomy as Definitive Treatment

• It fully decompresses involved compartments
• May not be necessary
  • Based on history, physical exam, symptoms, and compartment pressures
• Contraindicated with muscle death

• 80% successful for the anterior compartment

• ~60% successful for the deep posterior compartment

Fasciotomy Techniques

• Single Incision
• Two Incision

Poor Outcomes Due to Delayed/Missed Diagnosis

• Damaged nerves and paralysis
• Muscle necrosis and fibrosis
• Muscle contracture
• Release of myoglobin
• Kidney Damage
• Rhabdomyolysis
• Fracture nonunion and possible limb amputation

Chronic Exertional Compartment Syndrome (CECS)

• An overuse injury that typically affects young endurance athletes
• Results from increased pressure within the muscle compartments of the lower leg

Pathogenesis

• Exercise increases blood flow to active muscles, causing them to expand and swell.
• Swelling within surrounding noncompliant fascia increases pressure within the muscle compartment.
• Increased pressure reduces blood flow, leading to muscle ischemia and pain when metabolic demands can not be met.

Symptoms

• Gradually increasing pain in a specific muscle region during physical exertion.
• Pain is described as aching, squeezing, cramping, or tightness.
• Pain completely resolves with rest within 10-12 minutes.
• Often occurs bilaterally.
• Paresthesia, numbness, and foot-drop can occur.

Physical Exam

• Often unremarkable and can be misdiagnosed
• Helpful to examine after exercise, as the involved compartment may be tender
• Relative muscle weakness compared to pre-exercise evaluation may be noted
• Abnormal distal pulses are uncommon

Differential Diagnosis

• Medial Tibial Stress Syndrome (MTSS)
• Stress Fracture and Tendinopathy
• Deep Vein Thrombosis (DVT)
• Lumbar Radiculopathy and Nerve Entrapment
• Periostitis
• Intermittent Claudication
• Myopathy and Bone Tumor

Diagnosis

• Compartment pressure measurements with the following criteria:
  • Pre-exercise pressure ≥ 15 mm Hg
  • 1 minute post-exercise pressure of ≥ 30 mm Hg
  • 5 minute post-exercise pressure of ≥ 20 mm Hg

Imaging Studies

• Imaging to rule out other potential etiologies:
  • X-ray, Bone Scan, MRI, and Ultrasound

Conservative Treatment

• Reduce Training Volume
• Running on softer surfaces
• Orthotics
• Physical Therapy
• Ice
• OMT to address trigger points and improve venous/lymphatic return.

Prognosis

• Conservative treatment is poor without cessation of symptom-inducing activities.
• Surgical treatment appears to have better outcomes, with >90% showing significant pain relief and functional improvement.
• Return to play postoperatively varies but generally occurs between 8-12 weeks.