4-strand Tendon Research Articles

The influence of oblique sutures and tendon-suture anchorages on tensile resistance and ultimate strength of 4-strand tendon repairs.

This study investigated whether the integration of the oblique sutures contributes to the resistance to gapping in 4-strand flexor tendon repairs. In 72 porcine tendons, we compared repairs incorporating oblique sutures against those without using three distinct anchorage types. The studied suture configurations were longitudinal and oblique, modified Savage and Adelaide, and modified Kessler and Lahey. The number of tendons that formed the first gap or a 2 mm gap at the repair site during cyclic loading, stiffness at the 1st and 20th cycles, gap size between tendon ends and ultimate strength were recorded. No significant differences were found between core sutures with and without oblique sutures except between the modified Savage and Adelaide sutures. The Kessler-type anchorage was inferior in resisting gap formation than simple grasping or cross-locking sutures. We conclude that an oblique suture does not increase the gap resistance of 4-strand tendon repairs when using grasping or Kessler-type anchorages, but it does when using a cross-locking anchorage, such as the Adelaide suture. Simple grasping anchorage is comparable to cross-locking in resisting gap formation.

Gap Resistance and Tensile Strength of a Q Suture Technique During Curved Loading: An ExVivo Porcine Flexor Tendon Study.

This study aimed to determine the mechanical properties of the double Q suture technique in angular motion and to compare the gap formation associated with tendon repairs during curved and linear loading. Eighty porcine flexor tendons were repaired with one of two 4-strand sutures: double Q suture or double modified Kessler plus peripheral running sutures. The repaired tendons were cyclically loaded sequentially against a pulley with a radius of 2.0, 1.5, and 1.0 cm or linearly without any pulleys. The number of tendons that formed an initial or 2-mm gap at the repair site during cyclic loading, the gap size between tendon ends when cyclic loading ended, and the ultimate strength were recorded. The gap at the repair site formed gradually from the dorsal to volar aspect during curved loading. No double Q repairs, but half of the double Kessler plus running suture repairs, formed an initial or 2-mm gap on the volar aspect during curved loading. The double Q group had a significantly smaller gap size on the dorsal aspect than the double Kessler plus running suture group at all three radii of curvature. The ultimate strength was similar between the two groups. There were no significant differences in linear motion between these two repairs. The double Q suture is superior to the conventional 4-strand tendon core suture plus running peripheral sutures in gap resistance in angular motion. This study provides insight into the formation of an unbalanced gap on the dorsal and volar aspects of tendon repair during curved loading. The double Q suture provides a simple and efficient option for flexor tendon repair considering the high risk of gap formation on the dorsal aspects of the tendon repair in angular motion.

A new 4-strand tendon repair technique in a rabbit Achilles tendon model: Is 4 better than 6?

This study aimed to present a new modification of the modified Kessler tendon repair technique and share results of an animal study scrutinizing mainly the biomechanical properties and comparing it to other techniques. Eighteen New Zealand rabbits were used and divided into 3 groups: 1 experiment and 2 control groups. Four-strand modified Kessler and 6-strand Tang repairs were used for the control groups. The new modification was used in the experiment group. Two surgeries were conducted 8 weeks apart, repairing 1 Achilles tendon in the first, repairing the contralateral tendon and harvesting specimens in the second. The repair times were recorded. In addition, biomechanical tests were conducted to determine mechanical strength. There was a statistically significant difference between the 3 groups in load-to-failure values for the strength after repair model, with the experiment group superior to the other 2 (P = .002; P < .05). Although there was a noticeable difference between the mean loadto- failure values of each group in the healing model, we could not demonstrate a statistically significant difference(P > .05). The new modification took significantly less time than the other 2 techniques (P = .001). Our new modification was biomechanically stronger and faster than the other 2 techniques. The technique offers a new, suitable, practical option for human flexor tendon repair.

Comparative Study of Biomechanical Properties between Needled Suture and Needleless Suture in Multi-Strand Tendon Graft Model

Objective: To compare the biomechanical properties of the Chinese finger (CF) suture, a needleless suture technique, with the baseball stitch (BS) suture, a needled suture technique, in a multi-strand model by using a 4-strand tendon model. Additionally, the BS was compared with the serial rolling hitch (RH), a locking needleless suture technique. Materials and Methods: 4-strand grafts, made from two 20-cm fresh porcine toe extensors, were used in all three groups. After the grafts were sutured, pretension was applied with a load of 100-N distraction force for five minutes. After the tendon elongation was measured before and after the pretension, the distraction force was continued until the constructed graft failed. Stress-strain relationship graphs were recorded by universal testing machine (UTM), distributing to the calculation of percentage on tendon elongation, stiffness, and load-to-failure. Results: The BS had significantly higher load of failure than the CF (p=0.001) but no significant difference when compared with the RH. Comparing between BS, CF, and RH, there were no significant difference in stiffness and percentage of tendon elongation. In modes of failure, there was evidence of knot slipping in CF in six of six cases and graft strangulation in RH in four of six cases. Conclusion: Multi-strand model BS, a needled suture, had a higher load to failure than CF, a needleless suture. Moreover, needleless sutures had serious modes of failure, which were knot slipping and strangulation of graft by the suture material. Therefore, needleless suture technique for multi-strand tendon graft preparation was not recommended. Keywords: Tendon preparation; Multi-Strand; Needled suture; Needleless suture; Chinese finger; Baseball stitch; Rolling Hitch; Biomechanical study; Graft elongation; Load to failure

The impact of transverse components on 4-strand tendon repairs.

We investigated the effects of the transverse components of a tendon core suture on tensile resistance and strength of 4-strand repairs. Forty-four pig flexor tendons were repaired with one of the following four methods: double Tsuge, U-shaped, 4-strand cross and 4-strand rectangular repairs. We recorded the number of the repaired tendons that formed a 2 mm gap between the tendon ends during cyclic loading for 20 cycles, stiffness of the tendon at the 1st and 20th cycle, gap distance at the repair site and ultimate strength of the repair at the 20th cycle. When transverse components were added to the core suture, a greater number of tendons formed a 2 mm gap during cyclic loading. The stiffness gradually decreased, and the repair site's gap distance after cyclic loading increased with the presence of transverse components of the sutures. We conclude that the core suture's transverse components negatively impact the tensile resistance of 4-strand tendon repairs.

Effects of a Q Suture Technique on Resistance to Gap Formation and Tensile Strength of Repaired Tendons: An Ex Vivo Mechanical Study

The repair of digital flexor tendons following laceration should aim to prevent gapping at the repair site and restore the tensile strength of the tendons to facilitate postoperative movement. We present here a simple Q suture and test its effects on gap formation and tensile strength of the repaired tendons. Sixty porcine tendons were repaired with 3 2-strand sutures (Kessler, Kessler plus 2Q, and Kessler plus running sutures) and 3 4-strand sutures (double Kessler, double Kessler plus 2Q, and double Kessler plus running sutures). The specimens were subjected to a cyclic loading. At each cycle, the number of tendons that initiated gapping or formed a 2-mm gap at the repair site was determined. After the cyclic load testing, the gap distance between tendon ends and the ultimate strength of the repaired tendons was measured. In both 2-strand and 4-strand tendon repairs, augmentation by insertion of the 2Q sutures reduced the number of tendons that showed 2-mm gaps ends during loading. Compared with the single Kessler and Kessler plus running sutures, Kessler plus 2Q suture significantly increased the ultimate strength of the tendon repair. Compared with the double Kessler and double Kessler plus running sutures, double Kessler plus 2Q suture significantly decreased the gap distance at the repair site after cyclic loading. The Q suture technique effectively enhances the resistance to gap formation of 2-strand and 4-stand tendon repair. It also improves the tensile strength of 2-strand Kessler repairs. The Q suture is a simple technique that can resist gap formation and strengthen the tensile strength of the repaired tendons in the laboratory setting.

The Effect of Barbed Suture Tendon Repair on Work of Flexion

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. 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. There was no difference in mean maximum load and gap formation between the 2techniques. Work of flexion was higher for the barbed-suture repair group compared with the traditional repair group (39 N·mm vs 31 N·mm). The higher work of flexion in the barbed-suture group suggests that barbed suture may negatively affect tendon gliding within the flexor tendon sheath. 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.

Effect of Partial Versus Complete Circumferential Repair on Flexor Tendon Strength in Cadavers

This study investigated the strength of epitendinous repairs covering the palmar half of the tendon circumference only. Two hundred porcine tendons were harvested from pig feet and separated into 2 equal groups. Group 1 tendons were sutured with a 2-strand core repair and group 2 tendons were sutured with a 4-strand core repair. Each group was then divided into 5 equal subgroups (n=20). Four of the subgroups were sutured with 1 of the following epitendinous repairs: 50% simple running (50SR), complete simple running (100SR), 50% Silfverskiold (50SK), or complete Silfverskiold (100SK). One sub-group (0C) had no epitendinous repair. The core suture material was 3-0 braided polyester (Tricon; Tyco Healthcare, Dominican Republic), and the circumferential suture material was 6-0 polypropylene (Prolene, Sumerville, NJ). The tendons were mechanically strained to failure, and force data were recorded. The 50SR and 50SK repairs significantly increased the force at 1-mm and 2-mm gap formation of both core repairs. The 50SR and 50SK repairs increased the ultimate force at failure of both core repairs by approximately 20%. Both 50% circumferential (50C) repairs increased repair strength at the points of initial gap formation more than at the point of ultimate force. The 50C repairs were approximately 50% as strong as the 100% circumferential (100C) repairs at 1-mm and 2-mm gap formation and approximately 70% as strong at the ultimate force of failure. The 50C repairs increased the tensile strength of 2-strand and 4-strand tendon repairs in vitro. The prevention of early gapping was more significant than the increase of strength at failure.

Influence of Core Suture Purchase Length on Strength of Four-Strand Tendon Repairs

Recently the length of core suture purchase has been identified as a variable affecting the strength of tendon repairs. The influence of the length of the core suture purchase on the strength of multistrand locking and grasping suture repairs, however, has not been studied extensively in transversely lacerated tendons. We assessed the effects of the length of the core suture purchase on the strength of three 4-strand grasping or locking repair techniques. Seventy-four fresh adult pig flexor tendons were cut transversely and repaired with 1 of 3 methods: double-modified Kessler, locking cruciate, and modified Savage. Each method was assessed using 2 different lengths of core suture purchase (1.0 and 0.4 cm). The tendons were subjected to a linear noncyclic load-to-failure test in a tensile testing machine. We recorded the forces required for gap formation, ultimate strength, stiffness of the tendon, and the mode of repair failure. The resistance to gap formation, the ultimate strength of all 3 repairs, and the stiffness of the tendons with the double-modified Kessler and modified Savage repairs decreased significantly as the length of core sutures decreased from 1.0 to 0.4 cm. Locking and grasping repairs had a similar decrease in strength when the purchase was decreased from 1.0 to 0.4 cm. All tendons with modified Savage repairs with 1.0-cm purchase failed by suture breakage and tendons with 0.4-cm purchase failed predominantly by pullout. The length of core suture purchase significantly affects the strength of these 4-strand tendon repairs. The forces required for gap formation and the ultimate failure of repairs with 0.4-cm purchase were 20% to 45% lower than those of the repairs with 1.0-cm purchase. Locking repairs did not show a greater capacity to offset the decrease in strength than grasping repairs when the length of core suture purchase was decreased from 1.0 to 0.4 cm. Our study indicates that the length of suture purchase directly influences the strength of both locking and grasping core tendon repair methods.

Effects of Locking Area on Strength of 2- and 4-Strand Locking Tendon Repairs

The area of the tendon within the locking suture configuration of the modified Pennington repair is an important determinant of eventual tendon strength. This 2-strand repair's loop configurations encompass a large cross-sectional area of the tendon. Many recently proposed repairs, however, consist of locks in a number of narrow sites on the tendon surface and most are multistranded. It is not clear how the area within the locks affects tendon strength and whether the effects of locking areas change according to the number of repair strands. In this study we investigate the effects of locking area on repair strength of 2- and 4-strand tendon repairs. Sixty-five fresh pig flexor tendons were divided equally into 6 groups and were transected completely. They were repaired with 2- or 4-strand techniques. The tendon-suture interface was a circle-locking junction and diameters of the locks were 1, 2, or 3 mm. The tendons were pulled in a tensile testing machine until failure of the repair and the mode of failure, 2-mm gap force, and ultimate strength were measured. In the tendons with either 2- or 4-strand repairs locks with a diameter of 2 or 3 mm had significantly greater gap formation force and ultimate strength than those of 1 mm. The gap formation and ultimate forces were not statistically different between tendons with locks of 2 or 3 mm in diameter. In both the 2- and 4-strand tendon repairs tested in this study repair strength increased as the diameter of locks of the repair increased from 1 mm to 2 or 3 mm. An increase in the diameter from 2 mm to 3 mm, however, did not increase the gap force and ultimate strength. These findings indicate that the cross-sectional area within the locks affects repair strength when the diameter of the locks is within a certain range (2 mm) and that further enlargement of the locking area does not increase strength.

Effect of suture locking and suture caliber on fatigue strength of flexor tendon repairs.

The objectives of this cadaveric study were 2-fold: to determine the effect of different locking configurations on the cyclical fatigue strength of flexor tendon repairs and to assess the differences between each repair when a 3-0 or 4-0 suture is used. One hundred twenty flexor digitorum profundus tendons were cut and repaired using nonlocked, simple locked, and cross-stitch locked variations of 2- and 4-strand flexor tendon repairs. Using an incremental cyclical loading protocol we performed 10 trials of each repair with both 3-0 and 4-0 sutures and analyzed the number of Newton-cycles to failure using a 3-way ANOVA. The use of a 3-0 suture led to a 2- to 3-fold increase in fatigue strength in all repairs tested and the fatigue strength of the 4-strand repairs was significantly greater than the 2-strand repairs. All repairs performed with 4-0 suture failed by suture rupture. Of the 3-0 suture repairs, the three 2-strand repairs and the 4-strand cross-stitch locked repair failed by suture rupture. In contrast, 6 of 10 of the 4-strand simple locked and nonlocked repairs failed by suture pullout. There was no significant difference in fatigue strength between the 2 locked and the nonlocked 2-strand repairs using either 3-0 or 4-0 suture. There also was no significant difference in holding capacity or fatigue strength between the simple locked or nonlocked 4-strand repairs. However, the 4-strand cross-stitch locked repair with a 3-0 suture had significantly improved fatigue strength and holding capacity compared with the other repairs tested. Based on the consistently inferior biomechanical performance of 4-0 suture, we recommend that 3-0 suture be considered for 2- or 4-strand tendon repairs when early active motion is planned. The orientation of the transverse and longitudinal components of simple locked repairs did not significantly influence their holding capacity or fatigue strength. The cross-stitch type of locked repair provides better holding capacity and fatigue strength compared with simple locked or nonlocked 4-stranded flexor tendon repairs.