The effects of elevated compartment pressure on tibial arteriovenous flow and relationship of mechanical and biochemical characteristics of fascia to genesis of chronic anterior compartment syndrome

Abstract

The purpose of this study is to evaluate the effects of increased compartment pressure on anterior tibial arteriovenous flow patterns and to determine whether mechanical and biochemical properties of fascia are responsible for compartment pressure abnormalities. Twenty patients with chronic anterior compartment syndrome (CACS) and 20 age-matched control subjects had compartment pressure measurements and analysis of tibial arterial and venous flow before and after fasciectomy. Fascia specimens were evaluated for thickness, stress failure, structural stiffness, and total collagen content and prevalence of collagen cross-linkage. Pressures were significantly elevated in patients with CACS versus control subjects (23.8 mm Hg vs 6 mm Hg). No significant difference in tibial arterial flow could be detected in either group (43 cm/sec mean vs 41.9 cm/sec mean). Venous drainage was severely impaired in patients with CACS but not in control subjects. CACS fascia was thicker and stiffer than control fascia specimens (0.35 mm +/- 0.12 mm, 109 +/- 65 MN/mm; versus 0.22 mm +/- 0.06 mm; 60.3 +/- 22 MN/mm). Fasciectomy normalized postoperative compartment pressures and improved venous drainage. Collagen content per unit mass was similar for both CACS and control fascia specimens, although collagen cross-linking was significantly lower in the CACS fascia than in the controls. Tibial venous drainage is impaired, but arterial flow is not in patients with CACS. Fascia thickness and structural stiffness can account for increased pressure in CACS compartments. Collagen content and cross-linkage are unrelated to fascia stiffness or thickness. Postoperative improvement in vascular hemodynamics and reduction in compartment pressure is caused by increased capacitance in the compartment after fasciectomy.