Histology and Type I Collagen, Tenascin and Elastin Expression in Autologous and Allogeneic Anterior Cruciate Ligamentoplasties.

Abstract

Background. Ligamentization has been accepted in Anterior Cruciate Ligament (ACL) surgery. The purpose of this study is to evaluate ligamentization of different allografts and autografts used as plasties through histological and type I collagen (COL1), tenascin (TEN) and elastin (ELA) expression analysis. Methods. Prospective study of patients who underwent ACL reconstruction with at least 1-year follow-up. Biopsies were taken by arthroscopy and tissue sections were stained with hematoxilin-eosin and Masson’s trichrome. Relative COL1, TEN and ELA expression was studied by RT-PCR. Hamstring tendon and intact ACL biopsies were used as controls. Results. Eleven patients with a mean age of 36.6 ± 12.0 years were included. In 9 cases, ACL reconstruction was carried-out with autologous hamstring tendons while in the 2 remaining patients ACL was reconstructed using an achilles allograft. COL1, TEN and ELA expression of plasties was significantly different to ACL but similar to hamstring tendon. Histological analysis showed a dense fibroconnective tissue with cells similar to tenocytes, which could not be classified neither as a tendon nor as a ligament. Conclusions. An ACL plasty, independently of its origin (autologous hamstring or allogeneic achilles) does not become a ligament, at least in our study period (5 years) but it does maintain ACL functionality.