Crosslinking characteristics of an epoxy-fixed porcine tendon: effects of pH, temperature, and fixative concentration

Injury to the anterior cruciate ligament (ACL) often results in functional instability within the knee joint and may induce a severe articular deterioration. Clinically, these patients may require an ACL reconstruction. In an attempt to develop an improved ligament prosthesis, a prototype xenograft--an epoxy-fixed porcine Achilles tendon--was developed. The study was intended to investigate the crosslinking characteristics of the epoxy-fixed porcine tendons fixed at different pHs (4.0, 7.4, 9.0, and 10.5), temperatures (4, 25, and 37 degrees C), and fixative concentrations (1, 2, or 4%). Samples of each group were taken out at various elapsed fixation periods. The crosslinking characteristics-fixation index, denaturation temperature, and moisture content-of each sample were determined. Additionally, the stiffness of the epoxy-fixed tendons under various fixation conditions was qualitatively compared. In the study it was noted that the color of porcine Achilles tendons remained natural after epoxy fixation. With increasing pH, temperature, or fixative concentration, the fixation indices and denaturation temperatures of the epoxy-fixed tendons increased. However, the fixed porcine tendons tended to be stiffer at a higher pH, temperature, or fixative concentration. The moisture contents of the epoxy-fixed tendons were relatively lower than the fresh ones, while they were approximately the same at different pHs, temperatures, and fixative concentrations. The implications of these findings for the epoxy-fixed porcine tendons in ACL reconstruction require further investigation.