Abstract: Ex-Vivo Biomechanical Study Comparing the Cross-Locked Cruciate Repair with a Continuous Suture Repair for Oblique Flexor Tendon Lacerations

INTRODUCTION: Flexor tendon injuries remain a contentious issue in hand surgery as reflected in the multitude of differing techniques. A significant proportion of tendon transections are oblique and they are typically managed in a similar fashion to straight transections, using a multi-strand technique. In our practice, we have observed that there is significant bunching at the repair sites when standard techniques are used to repair oblique lacerations, leading to impaired gliding through the intricate pulley system. We hypothesized that a simple running suture repair for oblique tendon transections would have a reduced cross-sectional area (CSA) at the repair site compared to a traditional repair yet would have a similar tensile strength. METHODS: 60 porcine tendons were completely transected to create oblique lacerations for repair. Tendons were randomly assigned to one of three repair groups: one cross-locked cruciate repair group with a 3-0 core polyester (Ethibond™) suture and 5-0 polypropylene (Prolene™) epitendinous repair, and two running repair groups with a 3-0 polyester or a 3-0 polytetrafluorethylene (PTFE, Seramon™) suture. No epitendinous repair was performed on the running repair groups. Biomechanical testing was carried out with a tensiometer. RESULTS: The running polyester and PTFE groups had similar ultimate strengths to the one cross-locked cruciate repair (89.9 ± 12.3 N, 80.7 ± 9.3N and 77.2 ± 16.4N respectively). No significant difference was found in the 2mm gap formation force between the groups. The percentage change in CSA post-repair was significantly less in the polyester and PTFE running suture groups compared to the cross-locked cruciate repair group (5.5 ± 2.9%, 4.9 ± 2.1% and 20.2 ± 5.3% respectively). CONCLUSION: We have shown that a running suture provides similar tensile strength when compared to traditional techniques for oblique lacerations. The running technique is not as intricate to perform or as difficult to master as a traditional multi-strand technique but it is simple to learn and produces equally solid repairs. Furthermore, the running repair with a reduced CSA at the repair site may facilitate better gliding in zone II injuries. Oblique tendon lacerations are a distinct clinical entity and should be managed accordingly.