Surface Modification of Extrasynovial Flexor Tendon Graft: an Experimental Study in a Canine Model in Vivo

INTRODUCTION: A tendon graft is indicated when a flexor tendon repair fails, or when tendon rupture or tendon transfer requires prolongation of the muscle-tendon unit. The effect of hyaluronic acid (HA) on flexor tendon repair has been investigated in many animal and clinical studies. Exogenously applied HA may prevent adhesion formation between the flexor tendon and surrounding tissue following tendon repair, without affecting tendon healing. Recent reports of carbodiimide modified HA(cd-HA) on the surface of extrasynovial tendon noted decreased gliding resistance between the tendon and its pulley system during repeated flexion/extension motion over 500 cycles in a canine model in vitro. Our recent in vivo studies demonstrated that cd-HA-gelatin treatment for graft tendon decreased digit work of flexion, adhesion formation, and tendon gliding resistance (manuscript in press by JBJS). However, this chemically modified HA would alter the tendon mechanical and biological properties are unknown. Therefore, in this study we investigate if cd-HA modification would induce some side effects on tendon to bone healing, tendon mechanical properties, and graft cellularity compared with saline treatment control using canine in vivo model.