Successful tendon repairs are reliant on the suture material having high tensile strength, no or little tissue response, good handling characteristics and little elastic/plastic deformation. Plastic deformation contributes to gap formation at a tendon repair site. Previous research has shown a gap greater than 4mm is likely to fail. Pre-tensioning is a commonly used method to improve the handling properties of sutures. This study investigates whether the plastic deformation demonstrated by two suture materials used in flexor tendon repair is affected by manual pre-tensioning. Twenty lengths of 3/0 Prolene (Ethicon, UK) and 3/0 Ethibond Excel (Ethicon, UK) were selected. Half of the sutures in each group were manually pre-tensioned (longitudinal stretch of 15N for 3s) prior to knot tying (standard surgical knot with six throws) and half were knotted without pre-tensioning. The suture lengths were measured before and after a standardised cyclical loading regime on a tensile tester. The regime was designed to represent the finger flexion forces produced in an active rehabilitation programme after tendon repair. All sutures were subsequently tested to their ultimate tensile strength.Introduction
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