American Association for Hand Surgery
Theme: Beyond Innovation

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Beyond Adding The Cord Suture: An Entirely New Approach to Tendon Repair
Weifeng Zeng, MD; Ruston J Sanchez, MD; Samuel O. Poore, MD, PhD; Aaron M. Dingle, PhD
University of Wisconsin - Madison, Madison, WI

Introduction: The methods of Zone II flexor tendon repair in fingers remains limited, and the outcomes unpredictable. Decades of research have focused on applying stronger suture material and increasing the number of core sutures, ultimately creating a bulky repair site, prone to external adhesions, core suture rupture or suture pull out and ultimately repair failure. Despite the increased strength and number of core sutures, unpredictable outcomes remain.
This study utilizes the discarded or not-repaired tendon tissue and novel suture techniques to enhance the strength and redistribute the forces to a regeneration tendon, to ultimately prevent adhesion formation and rupture.
Materials and Methods:
Pieces of flexor digitorum superficialis tendons (FDS) in zone II otherwise resected or not repaired were utilized to repair flexor digitorum profundus tendons (FDP) with two novel techniques: 1) Circumferential repair (CR): a whole segment of the FDS is wrapped around the repaired tendon. Five sutures anchor points are placed through the segment of FDS and FDP either side of the repair site, to secure the segment of FDS and provide strength. 2) Asymmetric repair (AR): ulnar/radial side of the FDS is resected and secured across the repair site by eight interrupted anchor points; 4 either side of the repair site, that pass through the FDS pieces and FDP.
Results: We applied circumferential repair and asymmetric repair in 10 pig's feet, as the structure of flexor tendon of the second and third digitorums are similar to human. In Zone II, all the FDS can provide a complete segment for CR (where FDS is completely severed), or a piece of FDS from ulnar/radial side for AR (where FDS is partially severed). The transverse 5-anchor-points suture technique and the transverse 4-anchor-points suture technique can be performed simply through the FDS pieces and FDP in either side of the repair site. The preliminary test shows the native reclaimed FDS tissue is intended to take the brunt of the force, redistributing the force away from the repair site. The FDS pieces covering the repair site will act as isolation to prevent adhesion forming between the regenerating tendon and the surrounding tissues.
Conclusions: The FDP injury in Zone II usually combines with the FDS complete/partial injury. These entire new approaches using the autologous tendon tissue from FDS are achievable. Both CR and AR are currently undergoing qualitative static linear strength testing and cyclical testing to compare the novel methods with conventional methods.


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