Biochemical composition and histologic structure of the forearm interosseous membrane.

Abstract

The purpose of this study was to determine the structure and composition of the forearm interosseous membrane (IOM). The IOM of 12 cadaver forearms was fixed in formalin. After fixation 5 individual IOM fiber bundles per arm were separated by dissection, excised, and processed with hematoxylin-eosin, trichrome, and Verhoff-vanGeison stains. Nine additional fresh forearms were dissected and 5 IOM fiber bundles per arm were analyzed using the hydroxyproline assay. Bundles were evaluated at ulnar, central, and radial locations. Histologic analysis of the IOM bundles obtained from the 12 fixed forearms showed an abundance of collagen in the main bundle central location (84% +/- 7.8%). A progressive increase in collagen was noted from distal to proximal bundles (r =.72). The hydroxyproline assay of collagen content of the main IOM bundle's central location from the 9 additional fresh forearms was 99.3% +/- 16.5%. There was no difference between bundles or location (power = 0.25 and 0.46). We found that the IOM possesses a large collagen content arranged in fibrillar structures surrounded by elastin. Collagen was abundant in the proximal bundles and decreased in the distal bundles.