Presence of modified fibroblasts in ischemic contracture of the intrinsic musculature of the hand.

Biopsies of fibrotic interosseous muscles were obtained from three patients with ischemic contracture of the intrinsic muscles of the hand. Control biopsies were taken from normal contralateral interossei and from normal interossei crushed three weeks earlier. Examination of the specimens from the affected muscles under the electron microscope demonstrated large numbers of modified fibroblasts with ultrastructural features of both fibroblasts and smooth muscle cells. The atypical fibroblasts observed resembled myofibroblasts seen in contracting wounds, Dupuytren's contracture, stenosing tenosynovitis, and idiopathic carpel tunnel syndrome. Biopsies from normal muscle and crushed normal muscle contained normal fibroblasts and smooth muscle cells but no modified fibroblasts. Active contraction of modified fibroblasts could be responsible for progressive muscle shortening seen in intrinsic contracture.