ABSTRACT
PURPOSE: We investigated the association between aging-induced apoptosis and cell proliferation in the anterior cruciate ligament (ACL) of aged patients. MATERIALS AND METHODS: Twenty patients with osteoarthritis who underwent total knee replacement arthroplasty were enrolled in the study. They were divided into three groups according to age: group A ( or =76 years). The ACL tissue was obtained intraoperatively and subjected to terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and immunohistochemistry to quantify the apoptosis and cell proliferation indices. RESULTS: Apoptosis occurred in all groups, with the highest apoptosis index found in group C, followed by that in groups B and A. A statistically significant positive linear correlation was observed, with a 1-year increase in age resulting in an average increase of 1.49 in the apoptotic index. The lowest cell proliferation index was observed in group C, followed by that in group B and group A, with a 1-year increase in age resulting in an average decrease of 1.0 in the cell proliferation index, which was a statistically significant negative linear correlation. Consequently, a statistically significant negative correlation was confirmed between the apoptosis and cell proliferation indices, whereby an increase of 1.0 in the apoptosis index was concurrent with a decrease of 0.45 in the cell proliferation index. CONCLUSION: Apoptosis occurred in the ACL of human knee joint. With increasing age, apoptosis increased and cell proliferation decreased.