The effect of remnant preservation on patterns of gene expression in a rabbit model of anterior cruciate ligament reconstruction.

BACKGROUND: Anterior cruciate ligament (ACL) reconstruction with remnant preservation technique had been thought to be a more favorable milieu for graft reinnervation, revascularization, and ligamentization. However, the influence of preserving tibial residual fibers on mRNA expression during the graft remodeling process has never been investigated.

MATERIALS AND METHODS: Healthy mature New Zealand white rabbits were randomly assigned to one of four groups: remnant dissected, remnant preserved, sham operated, and normal control. Ligament tissue was dissected at 2, 6, and 12 wk after surgery, and real-time PCR was performed using primers for VEGF, TGF-β1, COLlAl, COL3A1, GAP-43, and NT-3.

RESULTS: In the remnant preservation group, mRNA levels for matrix components COL l Al, COL3A1, growth factor TGF-β1, and nerve-related genesGAP-43 all increased 6 wk after surgery, compared with the remnant dissection group (P < 0.05). An increased level of VEGF mRNA was also detected in the remnant preservation group 12 wk after operation (P < 0.05). An increased level of NT-3 mRNA was also observed in the remnant preservation group 2 and 12 wk after operation (P < 0.05).

CONCLUSIONS: Our results suggest that there is a time dependent alteration of angiogenesis-promoting, repair-related, and nerve-related gene expression after ACL reconstruction during the process of graft remodeling. Furthermore, they demonstrate that remnant preservation in ACL reconstruction determines the different molecular profiles of these target genes, especially during the early stages of graft remodeling, which perhaps explains the potential role in promoting revascularization, reinnervation, and ligamentization.