Knotless Tendon Repair with a Resorbable Barbed Suture: An In-vivo Comparison in the Turkey Foot.

Background: Un-knotted barbed suture constructs are postulated to decrease repair bulk and improve tension loading along the entire repair site resulting in beneficial biomechanical repair properties. Applying this repair technique to tendons has shown good results in ex-vivo experiments previously but thus far no in-vivo study could confirm these. Therefore, this current study was conducted to assess the value of un-knotted barbed suture repairs in the primary repair of flexor tendons in an in-vivo setting. Methods: Two groups of 10 turkeys (Meleagris gallapovos) were used. All turkeys underwent surgical zone II flexor tendon laceration repairs. In group one, tendons were repaired using a traditional four-strand cross-locked cruciate (Adelaide) repair, while in group two, a four-strand knotless barbed suture 3D repair was used. Postoperatively repaired digits were casted in functional position, and animals were left free to mobilise and full weight bear, resembling a high-tension post-op rehabilitation protocol. Surgeries and rehabilitations went uneventful and no major complications were noted. The turkeys were monitored for 6 weeks before the repairs were re-examined and assessed against several outcomes, such as failure rate, repair bulk, range of motion, adhesion formation and biomechanical stability. Results: In this high-tension in-vivo tendon repair experiment, traditionally repaired tendons performed significantly better when comparing absolute failure rates and repair stability after 6 weeks. Nevertheless, the knotless barbed suture repairs that remained intact demonstrated benefits in all other outcome measures, including repair bulk, range of motion, adhesion formation and operating time. Conclusions: Previously demonstrated ex-vivo benefits of flexor tendon repairs with resorbable barbed sutures may not be applicable in an in-vivo setting due to significant difference in repair stability and failure rates. Level of Evidence: Level IV (Therapeutic).

Midcarpal Arthrodesis Biomechanics: Memory Staples versus Cannulated Screws.

BACKGROUND: Midcarpal arthrodesis is a treatment of choice in patients with midcarpal arthritis. Traditionally a four corner fusion has been favoured, however recent research has shown improved results when the triquetrum and scaphoid are excised. There is no clear evidence as to which remaining bones should be fused or which implants should be used. The purpose of this study is to compare the biomechanics of midcarpal arthrodesis after scaphoid and triquetrum excision, using memory staples or cannulated screws, in recognised construct patterns. METHODS: 36 identical sets of carpal bones were 3D printed from acetyl butyl styrene. Midcarpal arthrodeses were performed in three configurations with shape memory alloy staples or headless compression screws. This gave 6 treatment groups; lunocapitate single staple or screw, lunocapitate with 2 staples or screws, three corner fusion with 2 staples or screws. Peak torque to distraction was measured and analysed. RESULTS: The peak torque to distraction was significantly greater in almost all constructs utilizing screws compared to staples, with two lunocapitate screws having the highest peak torque at both 1 and 3 mm distraction with 244 Nmm and 749 Nmm respectively (p < 0.05). CONCLUSIONS: Constructs utilizing screws have a peak torque to distraction significantly higher when compared to staples. Our recommendation when performing a midcarpal arthrodesis after scaphoid and trapezium excision is to fuse the midcarpal joint with 2 headless compression screws.

Influence of locking stitch size in a four-strand cross-locked cruciate flexor tendon repair.

PURPOSE: The 4-strand cross-locked cruciate technique (Adelaide technique) for repairing flexor tendons in zone II is a favorable method in terms of strength and simplicity. The purpose of this study was to investigate the effects of varying the cross-lock stitch size in this repair technique. Outcomes measured were load to failure and gap formation. METHODS: We harvested 22 deep flexor tendons from adult pig forelimbs and randomly allocated them into 2 groups. After cutting the tendons at a standard point, we performed a 4-strand cross-locked cruciate repair using 3-0 braided polyester with either 2-mm cross-locks (n = 11) or 4-mm cross-locks (n = 11). All repairs were completed with a simple running peripheral suture using 6-0 polypropylene. Repaired tendons were loaded to failure and the mechanism of failure, load to failure, stiffness, and load to 2-mm gap formation were determined. RESULTS: All repairs failed by suture breakage; we noted no suture pullout. There was no difference in load to failure (71.7-71.1 N; p = .89) or stiffness (4.1-4.6 N/mm; p = .23) between the 2-mm cross-lock and the 4-mm cross-lock groups. There was a trend toward higher resistance to 2-mm gap formation with the 4-mm cross-locks (55-62.2 N; p = .07). CONCLUSIONS: Four-strand cross-locked cruciate repairs with cross-lock sizes of 2 and 4 mm provide high tensile strength and are resistant to pullout. Repairs with 4-mm cross-locks tend to provide a more central load distribution and better gapping resistance than repairs with 2-mm cross-locks.