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DIAGNOSIS CHRONIC COMPARTMENT SYNDROME
the fascia. Qvarfordt et al., in a study of 15 patients with CCS, showed that there was a pronounced increase in lactate concentration immediately post-exercise in the same patients before fasciectomy (4.9 +/- 0.6 mmol/ kg) compared with post-exercise after fasciotomy (3.1 +/- 0.7 mmol/kg) (14). They also observed an increase in post-exercise water content both before and after fasciectomy, confirming understood physiology in exercising muscle. Wallensten and Eriksson also showed an increase in muscle water content in the anterior compartment following exercise but reported no obvious increase in the lactate concentration (15). n Externally applied pressure, eg. taping, bracing and casts.
Tissue perfusion There are several theories that attempt to explain how the rise in intramuscular pressure causes a compromise in tissue perfusion: n Arterial spasm: this is thought to be mediated by a non-sympathetic antidromic reflex. n Critical closure theory: if tissue pressure rises significantly or if arteriolar perfusion pressure drops, then the gradient across the vessel wall drops below the critical closing pressure necessary to keep the vessel patent (law of Laplace). n Microvascular occlusion theory: rising tissue pressure causes passive collapse of soft-walled capillaries, resulting in a reduced flow. n AV gradient theory: increase in tissue pressure increases the local venous pressure, reducing the local AV gradient. This results in reduced blood flow and oxygenation, which impairs muscle function and viability. Whiteside et al. published the results of a large series, using a dog as a model for CCS. They showed that tissue injury increased as the duration of ischaemia increased (16). As the pressure within a closed
compartment rises, the perfusion of tissue within that compartment declines progressively until it becomes significantly hampered at a level about 10–20 mmHg below the diastolic pressure. When the pressure within the closed compartment rises equals the diastolic pressure, tissue perfusion ceases, even though distal pulses may still be present. When the pressure
approaches systolic pressure, there is no tissue perfusion and the distal pulses disappear. Heppenstall et al. put forward the concept of perfusion index (Delta-P) (17). This was the difference between mean arterial blood pressure and ICP. Heppenstall et al. proved that the patient’s blood pressure was an important factor and that ICP was only an indirect indicator of muscle viability.
Summary of pathophysiology Increased tissue pressure is a prerequisite for the development of both the acute and chronic forms of compartment syndrome. The syndromes differ only in their degree of severity. In susceptible individuals, the fascial compartment is too small to accommodate the 20% increase in size of the muscle mass that typically occurs with heavy exercise.
AETIOLOGY Chronic compartment syndrome commonly affects young, active individuals who participate in endurance and high-impact sports. The symptoms are often related to running and it is therefore seen in many sports, as running forms part of many training programmes. Beckham et al. compared the anterior compartment pressure in asymptomatic competitive runners and cyclists (18). The results showed that there was no significant difference in the resting pressures, but the pressures were significantly higher in runners after maximal exercise (P=0.016). Unaccustomed increase in activity
or symptoms occurring at the start of the season was reported by Allen and Barnes (12) as being relevant and significant.
Others have reported symptoms occurring after: n an increase in activity, training and intensity n a change of training or playing surface n a change of footwear n a combination of some of the above. Abnormal biomechanical factors are considered widely to be predisposing factors.
The exact aetiology and the reason why some individuals are susceptible to CCS remain unknown, but a pattern is emerging as larger series are reported.
Figure 3: Online dynamic intracompartmental pressure (ICP) tracing of bilateral anterior and deep posterior compartments
ON EXERTION THAT IS RELIEVED WITH REST
CLINICAL SYMPTOMS The cardinal feature of CCS is pain on exertion that is relieved with rest. Wallensten and Eriksson described this pain as “claudication-like” (15). Mavor described his patients’ symptoms as “tightness” rather than a cramp, increasing in severity with exercise and always forcing them to rest (6). The description of the symptoms, however, is not consistent, as shown by Reneman, whose subjects used the terms “piercing”, “contracting”, “cramp- like” and “burning” (7). Medial-sided tibial pain is usually
described as “soreness” or a “dull ache”, often as deep pain in the calf. The lateral-sided tibial pain may be more aching and cramping in quality
THE CARDINAL FEATURE OF CCS IS PAIN
Figure 2: Bilateral anterior and deep posterior compartments cannulated, catheterised and linked to pressure transducers
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