The modified Nice knot has improved mechanical performance compared to the cinch stitch for meniscal root repair.

PURPOSE: According to previous biomechanical studies, the success of meniscus root repair depends on the suture-meniscus interface and optimisation of this procedure seems to be critical. A progressive, reliable and adjustable knot has numerous advantages in meniscal repair since the surgeon can adapt and meticulously tune the final strength of the fixation. We hypothesised that a single passage of one tape at two different points of the posterior meniscal root with a modified Nice knot configuration may allow similar or superior fixation for root repair compared to the cinch stitch suture technique. METHODS: Posterior root repair of medial and lateral meniscus was performed on 26 porcine knees. In group (A), two simple cinch stitches were applied, and in group (B), a modified Nice knot was used in a crossmatch configuration. For both groups, two passages through the meniscus with a 2-mm braided tape were used, and a single transosseous tibial tunnel technique was performed and tested in pull-out conditions. RESULTS: The modified Nice knot showed an improved biomechanical performance considering the maximum failure load for both the medial (600.7 ± 77.5 N) and lateral (686.1 ± 83.5 N) (p = 0.006) posterior root fixation when compared to a double cinch stitch (558.0 ± 123.9 N) and (629.0 ± 110.2 N) (p = 0.178) for medial and lateral fixation, respectively. The maximum stiffness was also higher for the modified Nice knot configuration for both medial (17.1 ± 1.5 vs. 13.3 ± 1.6 N/mm) and lateral meniscus (20.0 ± 2.6 vs. 13.8 ± 2.3 N/mm), being this difference statistically significative (p = 0.001). CONCLUSIONS: The modified Nice knot allowed better adaptation in the pull-out tests and presented higher fixation strength, stiffness and reproducibility, with lower standard deviation, being at the same time economically advantageous, since only one tape is needed. LEVEL OF EVIDENCE: Level III.

Abrasiveness of high-strength sutures used in rotator cuff surgery: are they all the same?

BACKGROUND: The suture-tendon interface remains the most common point of failure in rotator cuff repairs via suture pullout. Several high-strength braided sutures are available for rotator cuff surgery and are more abrasive than monofilaments. However, a comparison of these sutures has not been performed in a tissue model. METHODS: Ninety infraspinatus sheep tendons were randomized among 9 groups of sutures (n = 10), including FiberWire (Arthrex, Naples, FL, USA), Collagen Coated FiberWire (Arthrex), Orthocord (DePuy Mitek, Raynham, MA, USA), MaxBraid (Biomet, Warsaw, IN, USA), Force Fiber (Teleflex, Research Triangle Park, NC, USA), ULTRABRAID (Smith & Nephew, Memphis, TN, USA), Phantom Fiber BioFiber (Tornier, Bloomington, MN, USA), and Ti-Cron (Syneture, Mansfield, MA), with Surgipro (Syneture) monofilament as a control. Each suture was cycled 50 times through the tendon, which was fixed to a mechanical testing system under a constant load in saline solution. The distance cut through the tendon was measured and divided by the distance of suture sliding to determine displacement (mm/cm). Twist angle and picks per inch of each suture were measured using digital photography. One-way analysis of variance was used to compare the displacement and twist angle between sutures. RESULTS: Collagen Coated FiberWire was the most abrasive of the high-strength sutures. Four of the sutures (Collagen Coated FiberWire, Phantom Fiber BioFiber, FiberWire, Ti-Cron) had a mean displacement rate greater than 0.150 mm/cm. The remainder of the sutures had a mean displacement rate less than 0.050 mm/cm (Orthocord, Force Fiber, MaxBraid, ULTRABRAID). The difference in the displacement rates between these 2 groups was significant (P < .0001) and was related to both the twist angle and the picks per inch. CONCLUSION: Significant differences in suture abrasiveness were identified among high-strength braided sutures and correlated with lower twist angle and lower picks per inch.

The effect of barbed suture tendon repair on work of flexion.

PURPOSE: To compare the work of flexion, ultimate strength, and gap resistance of a conventional 4-strand tendon repair to a knotless barbed-suture 4-strand tendon repair. METHODS: Tendon repairs were performed on 16 cadaver flexor digitorum profundus tendons using either a 4-strand double Kessler repair or a similar but knotless 4-strand repair with a unidirectional barbed suture. Work of flexion, gap resistance during cyclical loading, and ultimate strength of both techniques were determined and their means compared. RESULTS: There was no difference in mean maximum load and gap formation between the 2 techniques. Work of flexion was higher for the barbed-suture repair group compared with the traditional repair group (39 N·mm vs 31 N·mm). CONCLUSIONS: The higher work of flexion in the barbed-suture group suggests that barbed suture may negatively affect tendon gliding within the flexor tendon sheath. CLINICAL RELEVANCE: Knotless barbed-suture tendon repair leads to increased work of flexion compared with traditional flexor tendon repairs, which may result in an increased rupture incidence.

A Mechanical Evaluation of Zone II Flexor Tendon Repair Using a Knotless Barbed Suture Versus a Traditional Braided Suture.

PURPOSE: To determine repair site bulk, gliding resistance, work of flexion, and 1-mm gap formation force in zone II flexor tendon lacerations repaired with knotless barbed or traditional braided suture. METHODS: Transverse zone II lacerations of the flexor digitorum profundus (FDP) tendon were created in 36 digits from 6 matched human cadaveric pairs. Repair was performed with 2-0 barbed suture (n = 18) or 3-0 polyethylene braided suture (n = 18). Pre- and postrepair cross-sectional area was measured followed by quantification of gliding resistance and work of flexion during cyclic flexion-extension loading at 10 mm/min. Thereafter, the repaired tendons were loaded to failure. The force at 1 mm of gap formation was recorded. RESULTS: Repaired FDP tendon cross-sectional area increased significantly from intact, with no difference noted between suture types. Gliding resistance and work of flexion were significantly higher for both suture repairs; however, we identified no significant differences in either nondestructive biomechanical parameters between repair types. Average 1-mm gap formation force with the knotless barbed suture (52 N) was greater than that of the traditional braided suture (43 N). CONCLUSIONS: We identified no significant advantage in using knotless barbed suture for zone II FDP repair in our primary, nondestructive mechanical outcomes in this in vitro study. CLINICAL RELEVANCE: In vivo studies may be warranted to determine if one suture method has an advantage with respect to the parameters tested at 4, 6, and 12 plus weeks postrepair and the degree of adhesion formation. The combined laboratory and clinical data, in additional to cost considerations, may better define the role of barbed knotless suture for zone II flexor tendon repair.

Biomechanical Testing of a Novel Device for Sutureless Nerve Repair.

Suboptimal nerve end alignment achieved with conventional nerve repair techniques may contribute to poor clinical outcomes. In this study, we introduce Nerve Tape®, a novel nerve repair device that integrates flexible columns of Nitinol microhooks within a biologic backing to entubulate, align, and secure approximated nerve ends. This study compares the repair strength of Nerve Tape with that of conventional microsuture repairs. Thirty small (2 mm) and 30 large (7 mm) diameter human cadaveric nerves were transected and repaired utilizing Nerve Tape or appropriate microsuture technique. Biomechanical testing was performed using a horizontal tensile tester. The repaired nerves were loaded until failure at a distraction rate of 40 mm/min, and the maximum failure load was determined. In the small nerve groups, the load-to-failure for Nerve Tape repairs (2.33 ± 0.66 N) was significantly higher than for suture repairs (1.22 ± 0.52 N; p < 0.05). In the large nerve groups, no significant difference in load-to-failure was found between Nerve Tape (7.45 ± 2.66 N) and suture repairs (5.82 ± 1.59 N: p = 0.12). Suture repairs tended to fail by rupture, whereas Nerve Tape failures resulted from microhook pullout. Nerve Tape is a novel nerve coaptation device that provides mechanical repair strength equal or greater to clinically relevant microsuture repairs.

The consistency and reliability of six-strand and four-strand flexor tendon repairs: a comparative porcine cadaveric study.

The aim of this study was to compare the consistency and reliability of the six-strand Gan modification of the Lim-Tsai flexor tendon repair with the four-strand Adelaide repair, both with 3-0 sutures and with eight to ten runs of simple 5-0 running peripheral suture as well as the influence of the surgeons' level of experience on the strength of the repair in a cadaveric animal setup. Thirty-nine surgeons repaired 78 porcine flexor digitorum profundus tendons with either the Adelaide technique (39 tendons) or the modified Lim-Tsai technique (39 tendons). Each repaired tendon was tested in a material testing machine under a single cycle load-to-failure test. The forces were recorded when the gap between the two tendon stumps reached 1 and 2 mm and when irreversible elongation or total rupture occurred. We found no significant differences in gap formation force and yielding strength of the tendons between the two methods. The surgeon's previous experience in tendon repairs did not improve the consistency, reliability or tensile strength of the repairs. We conclude that if a strong peripheral suture is added, the modified Lim-Tsai repair has the same technical reliability and consistency as the Adelaide repair in term of ultimate loading strength in this test setup.

Investigations into flexor tendon repair: a research journey over three decades.

In this article, I review how my team and I addressed clinical concerns in Zone 2 flexor tendon repair, and how major findings in each step of our research were translated into clinical practice. The focus of the article is on the thought processes behind each new investigation, the interpretation of research findings and conclusions drawn from the basic and clinical studies.

Comparison of the strength of two multi-strand tendon repair configurations in a chicken model.

We sought to investigate the strength of two multi-strand tendon repair configurations in a chicken model. Fifty-six chicken flexor tendons were repaired with one to two different four-strand configurations: 1) a four-strand repair consisting of a two-strand core modified Kessler suture with a circle loop repair and 2) a four-strand core Kessler suture repair with three separate peripheral suture points. The strength of the repaired tendons were measured 2, 3 and 4 weeks after the surgical repair and were analyzed statistically. The strength of the two repair methods was not statistically different 2 weeks after surgery. The tendons repaired with the four-strand core Kessler suture repair and three separate peripheral suture points were significantly stronger than those repaired with a two-strand core modified Kessler suture and a circle loop repair at 3 weeks (P = 0.033) and 4 weeks (P = 0.039). The four-strand repair with three separate peripheral suture points had greater strength than a two-strand repair with one circle loop suture based on an in vivo chicken flexor tendon model.

Delayed Lateral Row Anchor Failure in Suture Bridge Rotator Cuff Repair: A Report of 3 Cases.

Compared to single row repair, use of lateral row anchors in suture bridge rotator cuff repair enhances repair strength and increases footprint contact area. If a lateral knotless anchor (push-in design) is inserted into osteoporotic bone, pull-out of the lateral row anchor can developed. However, failures of lateral row anchors have been reported at several months after surgery. In our cases, even though complete cuff healing occurred, delayed pull-out of the lateral row anchor in the suture bridge repair occurred. In comparison to a conventional medial anchor, further biomechanical evaluation of the pull-out force, design, and insertion angle of the lateral anchor is needed in future studies. We report three cases with delayed pull-out of lateral row anchor in suture bridge rotator cuff repair with a literature review.

Recent developments in flexor tendon repair techniques and factors influencing strength of the tendon repair.

Over the last decade, both basic researchers and surgeons have sought to identify the most appropriate techniques to be applied in flexor tendon repairs. Recent developments in experimental tendon repairs and clinical outcomes of newer repair techniques have been reviewed in an attempt to comprehensively summarize the most critical mechanical factors affecting the performance of tendon repairs and the surgical factors influencing clinical outcomes. Among them, attention to annular pulleys, the purchase and tension of the core suture, and the direction and curvature of the path of tendon motion have been found to be determining factors in the results of tendon repair.

Evaluation of shear bond strength of repair acrylic resin to Co-Cr alloy.

PURPOSE: The purpose of this study was to investigate the impact of different surface treatment methods and thermal ageing on the bond strength of autopolymerizing acrylic resin to Co-Cr. MATERIALS AND METHODS: Co-Cr alloy specimens were divided into five groups according to the surface conditioning methods. C: No treatment; SP: flamed with the Silano-Pen device; K: airborne particle abrasion with Al2O3; Co: airborne particle abrasion with silica-coated Al2O3; KSP: flamed with the Silano-Pen device after the group K experimental protocol. Then, autopolymerized acrylic resin was applied to the treated specimen surfaces. All the groups were divided into two subgroups with the thermal cycle and water storage to determine the durability of the bond. The bond strength test was applied in an universal test machine and treated Co-Cr alloys were analyzed by scanning electron microscope (SEM). Two-way analysis of variance (ANOVA) was used to determine the significant differences among surface treatments and thermocycling. Their interactons were followed by a multiple comparison' test performed uing a post hoc Tukey HSD test (α=.05). RESULTS: Surface treatments significantly increased repair strengths of repair resin to Co-Cr alloy. The repair strengths of Group K, and Co significantly decreased after 6,000 cycles (P<.001). CONCLUSION: Thermocycling lead to a significant decrease in shear bond strength for air abrasion with silica-coated aluminum oxide particles. On the contrary, flaming with Silano-Pen did not cause a significant reduction in adhesion after thermocycling.