Pathological Changes of Human Ligament After Complete Mechanical Unloading

Abstract

To investigate the pathologic changes with a time sequence among patients with injured ligaments after complete mechanical unloading, based on a human anterior cruciate ligament (ACL) model. Pathologic examinations were done on remnants of completely ruptured ACLs at various times up to 14 wks after injury on 31 patients and on normal ACLs from five cadaver donors. Testing variables included fibroblast density, crimp amplitude, and crimp nuclear shape. Sequential changes were observed: Fibroblast density significantly increased within 5-6 wks of unloading. By 7-8 wks, crimp amplitude significantly decreased, accompanied by formation of irregular fiber patterns and fragments. This was followed by crimp wavelength and nuclear shape change within 9-14 wks. These pathologic findings suggest that the ACL undergoes significantly deleterious changes from 5 to 6 wks after mechanical unloading. This study may emphasize the important concept of early implementation of mechanical force in rehabilitation programs for patients with injured ligaments.