Supplementary Core Sutures Increase Resistance to Gapping for Flexor Digitorum Profundus Tendon to Bone Surface Repair – An in vitro Biomechanical Analysis

We evaluated the effects of two types of supplementary core sutures on the tensile properties and resistance to gap formation of flexor digitorum profundus (FDP) tendon-bone repairs. Forty-five human cadaver FDP tendons were sharply released from their insertion sites and repaired to bone utilizing one of three repair techniques: four-strand modified Becker core suture (Becker only), modified Becker plus a figure-of-eight supplementary core suture (Becker plus figure-of-eight), and modified Becker plus a supplementary core suture using a bone anchor (Becker plus anchor). Ultimate (maximum) force did not differ between repair groups. However, addition of a supplementary suture significantly increased repair-site stiffness and the 1, 2 and 3 mm gap forces, while decreasing the gap at 20 N compared to the Becker only suture ( P<0.05). The only difference between the two supplementary suture groups was that the Becker plus anchor group had increased stiffness compared to the Becker plus figure-of-eight group. In conclusion, a supplementary figure-of-eight suture and a supplementary suture using a bone anchor provide enhanced resistance to gap formation for FDP tendon–bone repairs.