Flexor tendon repair with a knotless barbed suture: a comparative biomechanical study.

Purpose To test the hypothesis that a flexor tendon repair with only a knotless barbed suture technique provides a repair with a greater maximal load to failure and 2-mm gapping resistance than a traditional technique using a 4-strand core plus a running-locking epitendinous suture. Methods We assigned 41 fresh-frozen cadaveric flexor digitorum profundus tendons for repair by either a traditional technique using a 4-strand core (Tajima and horizontal mattress) plus a running-locking epitendinous suture (n = 20) or a bidirectional barbed suture technique using a knotless, 4-strand core secured with 3 transverse passes (n = 21). A biomechanical study was performed on each tendon–suture construct and the tendons were linearly distracted to failure at 100 mm/min. The maximal tensile load to failure, 2-mm gapping tensile load, and mode of failure were determined and statistically compared. Results The average maximal load to failure was not significantly different between the traditional repair (48 ± 12 N) and the barbed suture repair (50 ± 14 N). The average 2-mm gapping load was also insignificantly different between the traditional repair (42 ± 12 N) and the barbed suture repair (32 ± 9 N). The traditional repair failed by knot unraveling and suture rupture 35% and 65% of the time, respectively. The barbed suture repair failed by suture pull-out and rupture 67% and 33% of the time, respectively. The average load to failure by suture rupture was insignificantly different between the traditional repair (51 ± 13 N) and the barbed suture repair (63 ± 16 N). The average load to failure by knot unraveling using the traditional repair was 43 ± 11 N, whereas the average load to failure by suture pull-out using the barbed suture repair was 43 ± 8 N. Conclusions The barbed suture repair did not demonstrate a significant difference in maximal load to failure and 2-mm gapping resistance compared with the traditional method of repair. Clinical relevance This study examines the biomechanical differences between 2 types of flexor-tendon repair, which can help guide the surgical management for these injuries.