A condition in which interstitial tissue pressures within an osteofascial compartment are elevated to sustained, nonphysiologic pressures.
Compartment syndrome may be considered as incipient, acute, late (delayed diagnosis), chronic/exertional, or from extrinsic compression such as from a constricting cast or splint.
In general, increasing pressure within a confined space will compromise the circulation and function of its contents.
The law of Laplace determines the equilibrium about the vessel wall:
Pi – Po = T/R
where Pi is the pressure inside vessel
Po is the pressure outside vessel
T is the vessel wall tension
R is the radius of vessel
Local blood flow (LBF) is determined by the following equation:
LBF = (Pa – Pv)/R
where Pa is the arterial pressure
Pv is the venous pressure
R is the local vascular resistance
Progressive pathologic alteration in compartmental physiology is described below:
Increased compartment pressure
Venous outflow obstruction
Increased capillary permeability
Increased intracompartmental pressure
Decreased arterial perfusion
Decreased tissue oxygenation
III. Pertinent Anatomy
Multiple osteofascial compartments have been described for the upper extremity (below); however, subcompartmentalization of these compartments, such as the flexor digitorum profundus within the volar forearm compartment, has been observed clinically.
Brachium/arm (Fig. 27.1)
Deltoid (anterior, middle, and posterior subcompartments)
Antebrachium/forearm (Fig. 27.2)
Dorsal compartment (superficial & degs)
Volar compartment (superficial & degs)
Hand (Fig. 27.3)
Carpal tunnel/distal ulnar tunnel
Dorsal and palmar interosseous compartments
IV. Compartment Syndrome: Etiology
There are many potential etiologies for the condition of compartment syndrome, including
Fracture or soft tissue injury (trauma)
Prolonged limb compression
Iatrogenic: excessive tourniquet ischaemia
Closure of fascial defects
Complications of intraoperative positioning
Intermittent, exercise induced
Remember: Compartment syndrome can develop in the presence of an open wound.
Figure 27.1 Cross-sectional illustration demonstrating the compartments of the upper arm. (Reprinted with permission. Copyright 2009: Leversedge FJ, Goldfarb CA, and Boyer MI.)
Figure 27.2 Cross-sectional illustration demonstrating the compartments of the forearm. (Reprinted with permission. Copyright 2009: Leversedge FJ, Goldfarb CA, and Boyer MI.)
V. Diagnostic Considerations
History of injury
Consider both intrinsic (intracompartmental bleeding/swelling) and extrinsic (tight cast or dressing) factors, which may elevate intracompartmental pressures.
External compression, such as from a constricting cast or splint, can contribute to the elevation of intracompartmental pressure.
Compartment syndrome, or an incipient condition, is primarily a clinical diagnosis although objective testing may be confirmatory.
Six “P”s are considered in the diagnostic evaluation of compartment syndrome:
Pain with passive stretch
Increased pressure of the affected compartment on palpation