Biomechanical, Muscle Activation and Clinical Characteristics of Chronic Exertional Compartment Syndrome

Abstract

Chronic exertional compartment syndrome (CECS) is a common problem within both military and athletic populations that can be difficult to diagnose. Furthermore, it is unclear what causes the development of CECS, particularly in the military population, as personnel undertake a variety of activities that can cause pain with CECS such as fast walking, marching and running. Chronic exertional compartment syndrome has been hypothesised to develop due to excessive muscle activity, foot pronation and abnormal biomechanics predominantly at the ankle. Treatment of CECS through running re-education to correct these abnormalities has been reported to improve symptoms. However no primary research has been carried out to investigate the biomechanical, muscle activation and clinical characteristics of military patients with CECS. The purpose of this thesis was to provide an original contribution to the knowledge through the exploration of these characteristics; and the development of insights into the development of CECS, with implications for prevention and treatment.

Study one investigated the clinical characteristics of 93 service personnel with CECS. Plantar pressure variables, related to foot type and anterior compartment muscle activity, and ankle joint mobility were compared during walking between 70 cases and 70 controls in study two. Study three compared three-dimensional whole body kinematics, kinetics and lower limb muscle activity during walking and marching between 20 cases and 20 controls. Study four compared kinematics and lower limb muscle activity during running in a separate case-control cohort (n=40). Differences in electromyography (EMG) intensity during the gait cycle were compared in the frequency and time domain using wavelet analysis. All studies investigated subject anthropometry.

Cases typically presented with bilateral, ‘tight’ or ‘burning’ pain in the anterior and lateral compartments of the lower leg that occurred within 10 minutes of exercise. This pain stopped all cases from exercising during marching and/or running. As such subsequent studies investigated the biomechanics of both ambulatory and running gaits.

Cases in all case-control studies were 2-10 cm shorter; and were typically overweight resulting in a higher body mass index (BMI) than controls. There was strong evidence from study 3 that cases had greater relative stride lengths than controls during marching gait. This was achieved through an increase in ankle plantarflexion during late stance and a concomitant increase in the gastrocnemius medialis contraction intensity within the medium-high frequency wavelets. Given the differences in height observed, this may reflect ingrained alterations in gait resulting from military training; whereby all personnel are required to move at an even cadence and speed. These differences in stride length were also observed in walking and running gaits although to a lesser extent.

There was no evidence from the EMG data that cases had greater tibialis anterior activation than controls during any activity tested, at any point in the gait cycle or in any frequency band. In agreement, there was also no evidence of differences between groups in plantar pressure derived measures of foot type, which modulate TA activity. Toe extensor - related plantar pressure variables also did not differ between groups. In summary, contrary to earlier theories, increased muscle activity of the anterior compartment musculature does not appear to be associated with CECS.