Biomechanical evaluation of flexor tendon repair using barbed suture material: a comparative ex vivo study

Biomechanical evaluation of the ST-knot: A new suture for flexor tendon repair

PURPOSE

Although tendon lacerations are common, there is currently no consensus on choice of suture. Easy and fast sutures that impart enough strength to allow mobilization are needed. This study compared the ex vivo biomechanical strength (force required to create a 2 mm tendon gap) of a novel suture (ST-knot) with that of a conventional suture (double Kessler).

MATERIALS AND METHODS

Forty fresh deep flexor tendons from porcine forelimbs were used. Both repaired tendon ends were mounted on standard traction jaws of an axial traction machine at an initial distance of 40 mm for all tendons. A high-definition camera was used to determine the force forming a 2 mm gap. Ten tendons in group 1 (ST-knot) and 10 in group 2 (double Kessler) were prepared with PDS 4.0 (single thread for Kessler, double thread for ST-knot). Tendons in groups 3 (ST-knot) and 4 (double Kessler) were repaired with PDS 1.0 using the same principle.

RESULTS

There was no significant difference in the force required to form a 2 mm tendon gap between groups 1 and 2, and this trend was identical when using a stronger thread in groups 3 and 4. The maximum force before rupture, mode of repair failure, stress and stiffness were also comparable, with no significant differences between groups 1 and 2, or between groups 3 and 4.

CONCLUSIONS

The ST-knot showed comparable results to the double-Kessler knot, whichever the thread used. Because it involves fewer steps than conventional techniques and is easy to perform, the ST-knot may offer a therapeutic solution, particularly in complex trauma with multiple tendon injury.

Biomechanical comparison of different suture materials with different techniques in tendon repair: An ex-vivo study

OBJECTIVES

Sheep Achilles tendons are used as an effective preclinical model of flexor tendon repair in plastic surgery, due to their biomechanical properties, which are similar to humans. The aim of this study was to examine the efficacy and biomechanical outcomes of suture materials and tendon repair techniques in flexor tendon repair.

MATERIAL AND METHODS

72 sheep tendons were obtained for a total of 12 different scenarios. Tendons were repaired using 4 different suture types and 3 different suture techniques. After repair, the tendons were fixed at both ends and subjected to biomechanical tests. Ultimate Failure Load (UFL) and 2-mm Gap Load (GL) per scenario were compared statistically within and between groups.

RESULTS

UFL and GL of all sutures were significantly different between the modified Kessler, Bunnell and Krackow techniques (P < 0.05), and between Monosorb, Ti-Cron and V-loc sutures (P < 0.05). UFL and GL according to repair technique were not significantly different for the Propilen suture (P > 0.05).

CONCLUSION

When UFL and GL were considered together, our findings indicate that optimal strength scenarios were for the modified Kessler technique using Monosorb or V-loc sutures.

The effect on incisional hernia of absorbable barbed suture for midline fascial closure in minimally invasive surgery for colorectal and gastric cancers: study protocol for a randomized controlled trial

BACKGROUND

Incisional hernia following abdominal surgery is a frequent complication of midline laparotomy. This complication is strongly associated with the technique and material used for suture. While a monofilament absorbable suture is recommended to prevent incisional hernia, it can lead to suture loosening or surgical-knot breakage. Although barbed sutures can be an alternative suture material in abdominal fascial closure, evidence for its safety and effectiveness is lacking. Therefore, we designed a prospective randomized trial to evaluate the safety and efficacy of absorbable barbed sutures for midline fascia closure in minimally invasive surgery for colorectal and gastric cancers in comparison with conventional absorbable monofilament sutures.

METHODS

A total of 312 patients who underwent minimally invasive surgery for colorectal and gastric cancers will be randomly allocated to either the absorbable barbed or monofilament suture group for abdominal fascia closure in a 1:1 ratio. The primary outcome is incisional hernia rate within 3 years after surgery, as verified by physical examination and computed tomography. Postoperative complications, including surgical site infection, postoperative pain, and quality of life, will be compared between two groups as secondary outcomes. The investigator will examine the patients until discharge and at 6, 12, 18, 24, and 36 months postoperatively.

DISCUSSION

This is the first randomized controlled trial to compare absorbable barbed sutures with monofilament sutures for midline fascia closure in minimally invasive surgery. If absorbable barbed sutures demonstrate superior results to those of monofilament sutures, this type of suture material may be recommended as an alternative option for abdominal fascia closure.

TRIAL REGISTRATION

KCT0007069. Registered on January 30, 2023.

Practice Patterns in Operative Flexor Tendon Laceration Repair: A 15-Year Analysis of Continuous Certification Data from the American Board of Plastic Surgery

The American Board of Plastic Surgery has been collecting practice data on operative repair of flexor tendon lacerations since 2006, as part of its Continuous Certification program.

Comparison of the mechanical properties and anchoring performance of polyvinylidene fluoride and polypropylene barbed sutures for tendon repair

Polyvinylidene fluoride (PVDF) has been considered as an alternative suture material to replace polypropylene (PP) due to its superior biocompatibility and mechanical properties, but it has never been examined for use in barbed sutures, particularly for tendon repair. This study fabricated size 2–0 PVDF and PP bidirectional barbed sutures and compared their mechanical properties and anchoring performance in patellar tendons. The mechanical properties were evaluated via tensile testing, and the anchoring performance of the barbed sutures was assessed by a tendon suture pullout test. Sixty porcine patellar tendons were harvested, transected to mimic a full‐thickness injury, and repaired using a cross‐locked cruciate suturing technique. The ultimate tensile force was 60% higher for the PVDF barbed sutures (22.4 ± 2.1 N) than for the PP barbed sutures (14.0 ± 1.7 N). The maximum pullout force was 35% higher for PVDF barbed sutures (70.8 ± 7.8 N) than for PP barbed sutures (52.4 ± 5.8 N). The force needed to form a 2‐mm gap, indicative of repair failure, was similar between the PVDF (29.2 ± 5.0 N) and PP (25.6 ± 3.1 N) barbed sutures, but both were greater than the 2‐mm‐gap forces for non‐barbed sutures of the same size. In this study, PVDF barbed sutures provided better mechanical properties and improved tissue anchoring performance compared to the barbed PP sutures for porcine patellar tendon repair, demonstrating that PVDF monofilament sutures can be barbed and used effectively for tendon repair.

Rehydration of the Tendon Fascicle Bundles Using Simulated Body Fluid Ensures Stable Mechanical Properties of the Samples

In this work, we investigate the influence of dehydration and subsequent rehydration of tendon fascicle bundles on their structural and mechanical properties by using distilled water, 0.9% NaCl, 10% NaCl, SBF, and double concentrated SBF (SBFx2). The properties of tendon fascicle bundles were investigated by means of uniaxial tests with relaxation periods and hysteresis for samples with various interfascicular matrix content, dissected from the anterior and posterior areas of bovine tendon. Uniaxial tests with relaxation periods and analysis of sample geometry and weight showed that dehydration alters the modulus of elasticity dependent on the interfascicular matrix content and influences the viscoelastic properties of tendon fascicle bundles. Tensile and relaxation tests revealed that changes resulting from excessive sample drying can be reversed by rehydration in an SBF bath solution for elastic strain range above the toe region. Rehydration in SBF solution led to minor differences in mechanical properties when compared to control samples. Moreover, anterior samples with greater interfascicular matrix content, despite their lower stiffness, are less sensitive to sample drying. The obtained results allow us to limit the discrepancies in the measurement of mechanical properties of wet biological samples and can be useful to researchers investigating soft tissue mechanics and the stability of transplant materials.

The use of barbed sutures in the Pulvertaft weave: a biomechanical study

The use of barbed sutures in tendon repair and reconstruction is advantageous because it allows for a knotless suturing technique. In this biomechanical study, we compared barbed sutures with conventional sutures in tendon transfers using the Pulvertaft weave technique in a human cadaveric model. Thirty human cadaveric finger flexor tendons were transected and divided into three groups of ten tendons, which were then reconstructed by the Pulvertaft weave technique using 3-0 Prolene (Ethicon, Inc., Somerville, NJ, USA), 3-0 Ethilon (Ethicon, Inc., Somerville, NJ, USA) or 3-0 V-Loc (Covidien Deutschland GmbH, Neustadt, Germany) sutures. Biomechanical testing showed that repairs in the V-Loc group had significantly greater ultimate tensile strength and stiffness than conventional sutures. The time taken to complete the weave and the length of sutures used were also the least in the V-Loc group. Our study has shown that the barbed suture has a better biomechanical performance than conventional suture types when used in the Pulvertaft weave technique.

The use of bidirectional barbed suture in the treatment of a complete common calcanean tendon rupture in a dog: Long-term clinical and ultrasonographic evaluation

The canine common calcanean tendon can be repaired successfully using a modified Kessler knotless barbed technique. A long-term ultrasound follow-up showed improved and increased normal tendon fibrillar echotexture and homogeneity.

The Impact of Suture Caliber and Looped Configurations on the Suture-Tendon Interface in Zone II Flexor Tendon Repair

PURPOSE

To evaluate the impact of suture caliber and looped configurations on the integrity of 4-strand modified Kessler zone II flexor tendon repairs during progressive cyclic loading.

METHODS

Seventy-two flexor digitorum profundus tendons from 18 fresh human cadaver hands were divided into 4 repair groups. Thirty-six matched tendons underwent repair using either a 4-0 looped or 4-0 single-stranded suture, and an additional 36 tendons underwent 3-0 looped or 3-0 single-stranded repairs. Repair strength was tested by progressive cyclic loading. The force generating 2-mm gap formation, ultimate failure, and the mechanism of failure were recorded for each test. The impact of looped versus single-stranded configurations and the effect of tendon cross-sectional area on repair integrity were analyzed for each suture caliber.

RESULTS

There was no statistically significant difference between groups regarding the force to 2-mm gap formation or ultimate failure, and all values exceeded the minimum threshold of 27 N required to withstand an early active range of motion rehabilitation protocol. The use of a 3-0 caliber suture resulted in a significantly higher proportion of repairs failing by suture pullout through the tendon substance, including 63.5% of looped and 38.9% of single-stranded core sutures. By comparison, this occurred in 11.1% of 4-0 looped and 0% of 4-0 single-stranded sutures. Larger tendon cross-sectional areas were associated with more robust repairs, particularly in the 3-0 looped group.

CONCLUSIONS

In a human cadaver flexor tendon repair model, there was no significant difference in the mean force to failure between all 4 flexor tendon repair constructs under progressive cyclic loading. However, the 3-0 caliber suture failed more frequently by suture pullout, particularly with the use of a looped suture.

CLINICAL RELEVANCE

Four-strand flexor tendon repairs using a 3-0 caliber suture are more prone to early failure by suture pullout under progressive cyclic loading compared with a 4-0 caliber suture.

Comparing Biomechanical Properties, Repair Times, and Value of Common Core Flexor Tendon Repairs

BACKGROUND

The aim of the study was to compare biomechanical strength, repair times, and repair values for zone II core flexor tendon repairs.

METHODS

A total of 75 fresh-frozen human cadaveric flexor tendons were harvested from the index through small finger and randomized into one of 5 repair groups: 4-stranded cross-stitch cruciate (4-0 polyester and 4-0 braided suture), 4-stranded double Pennington (2-0 knotless barbed suture), 4-stranded Pennington (4-0 double-stranded braided suture), and 6-stranded modified Lim-Tsai (4-0 looped braided suture). Repairs were measured in situ and their repair times were measured. Tendons were linearly loaded to failure and multiple biomechanical values were measured. The repair value was calculated based on operating room costs, repair times, and suture costs. Analysis of variance (ANOVA) and Tukey post hoc statistical analysis were used to compare repair data.

RESULTS

The braided cruciate was the strongest repair ( P > .05) but the slowest ( P > .05), and the 4-stranded Pennington using double-stranded suture was the fastest ( P > .05) to perform. The total repair value was the highest for braided cruciate ( P > .05) compared with all other repairs. Barbed suture did not outperform any repairs in any categories.

CONCLUSIONS

The braided cruciate was the strongest of the tested flexor tendon repairs. The 2-mm gapping and maximum load to failure for this repair approached similar historical strength of other 6- and 8-stranded repairs. In this study, suture cost was negligible in the overall repair cost and should be not a determining factor in choosing a repair.

Flexor Tendon Injuries

Flexor tendon injuries of the hand are uncommon, and they are among the most challenging orthopaedic injuries to manage. Proper management is essential to ensure optimal outcomes. Consistent, successful management of flexor tendon injuries relies on understanding the anatomy, characteristics and repair of tendons in the different zones, potential complications, rehabilitation protocols, recent advances in treatment, and future directions, including tissue engineering and biologic modification of the repair site.

In Vitro Comparison of Two Barbed Suture Configurations for Flexor Tendon Repair

Purpose  The current study compares the strength of a previously studied technique for flexor tendon repair with barbed sutures to an experimental approach that aligns all the barbs to oppose distraction. Methods  Twelve flexor tendons from cadaveric specimens were mechanically tested following repair of simulated zone II tendon injuries. Two repair techniques utilizing barbed sutures were studied: the Marrero-Amadeo four-core barbed suture approach and the experimental configuration with all barbs on four cores opposing distraction. Maximum applied load at failure, that is, ultimate load, and 2-mm gap force were compared between the two repair techniques, both as raw values and after normalization to cross-sectional area of the intact tendon. Statistical testing was performed using t -tests and Mann-Whitney U -tests, where appropriate, with a significance level of 0.05. Results  The ultimate loads, raw (58.2 N) and normalized (4.8 N/mm ² ), were significantly larger for the Marrero-Amadeo repair than the proposed experimental approach (35.6 N and 2.7 N/mm ² ; p  < 0.05). No significant differences were identified for 2-mm gap force. Conclusion  The innovation of suturing to align all barbs to oppose distraction does not improve strength of the repaired tendon. The Marrero-Amadeo technique was found to have superior strength for use in traumatic zone II flexor tendon injuries.

Biomechanical Analysis of Barbed Suture in Flexor Tendon Repair versus Conventional Method: Systematic Review and Meta-Analysis

BACKGROUND

The barbed suture technique uses newly developed materials for flexor tendon repair. In this study, the authors examine the effectiveness of using barbed sutures in flexor tendon repair compared with conventional methods.

METHODS

A systematic literature review and meta-analysis was performed using MEDLINE, Embase, and Cochrane databases. Barbed suture and conventional suture methods were extracted as predictor variables, and maximum force, gap formation force, and cross-sectional area were extracted as outcome variables. Subgroup analyses were performed according to the source of suture materials and the number of strands. The Newcastle-Ottawa Scale was used to assess the quality of studies. Publication bias was evaluated using funnel plots.

RESULTS

The search strategy identified 86 publications. After screening, 12 articles were selected for review. Barbed sutures are comparable in effectiveness to conventional methods in terms of maximum force, gap formation force, and cross-sectional area. In the subgroup analysis, barbed sutures also have comparable effects to conventional methods in terms of maximum force and gap formation force.

CONCLUSIONS

The authors' meta-analysis found that the use of barbed sutures in flexor tendon repair was competitive compared to conventional methods in terms of maximum force and gap formation force. Long-term in vivo studies are needed to confirm these findings.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Use of locking barbed sutures in foot and ankle surgery. A case series

BACKGROUND

Barbed sutures represent a novel technique for wound closure. By distributing tension forces across the length of a wound, it results in better wound healing. A recent article from Chowdhry et al. cautioned against the use of barbed sutures in foot and ankle surgery. Our experience with the Quill^® (Angiotech, Vancouver, BC) barbed suture, showed a more positive outcome.

MATERIALS AND METHODS

123 surgical wounds were prospectively followed up after closure with a bidirectional barbed suture. The cohort represented a large range of patient ages and co-morbidities, as well as incision length and locations.

RESULTS

Complication rates were low in this large cohort. The total complication rate was 6.5% (8 wounds). One wound (0.8%) had a major infection that needed further surgery, and 2 wounds (1.6%) showed inflammatory related complications. The remaining 5 wounds (4%) had minor wound complications, which resolved without any further surgical intervention. Patient satisfaction rates were high, with 78% of incisions scoring at maximum on the visual analogue cosmesis score.

CONCLUSIONS

Use of the Quill^® (Angiotech, Vancouver, BC) suture is a safe and effective alternative for wound closure in foot and ankle surgery.

Does Barbed Suture Repair Negate the Benefit of Peripheral Repair in Porcine Flexor Tendon?

Background: Advances in suture material and geometry have fueled interest in barbed suture tenorrhaphy. Theoretically, barbed suture allows better load distribution, smoother gliding under pulleys, and improved tendon blood flow. Minimal data exist on whether barbed tendon repair may benefit from supplementation by a peripheral stitch. The purpose of this study is to determine whether peripheral suture repair increases gap resistance in both conventional and barbed core repairs, increases maximum tensile strength, and fails before or after the core repair. Methods: Porcine flexor tendons were harvested and assigned randomly into 4 groups of 10 of varying suture constructs (3-0 PDS™ or 3-0 V-Loc 180™ core with or without peripheral 5-0 Vicryl™ repair). Core repairs were performed using a modified 4-strand cruciate repair. A servohydrolic tester was used for biomechanical testing of linear 2-mm gap resistance and maximum tensile strength. Results: Peripheral repair improved 2-mm gap resistance in all repairs, regardless of core suture type, conventional (173% increase) or barbed (204% increase). No change in the maximum tensile strength was found in either core suture type with peripheral repair. Peripheral repairs always failed before core repairs, at a significantly higher load of 74.2 ± 20.4 N in barbed versus 57.8 ± 12.2 N (P = .04) in conventional core repairs. Conclusions: The addition of peripheral repair improved gap resistance but not ultimate tensile strength in both conventional and barbed flexor tendon repairs in linear testing. The 4-strand cruciate flexor tendon repairs using barbed suture may require peripheral repair to withstand physiologic loads, as core repair alone using barbed suture was insufficient.

Comparison of Barbed Sutures in Porcine Flexor Tenorrhaphy

Background: Barbed suture use has become more popular as technology and materials have advanced. Minimal data exist regarding performance of the 2 commercially available products, V-LocTM and StratafixTM in tendon repairs. The purpose of this study was to compare gap resistance and ultimate tensile strength of both suture materials and nonbarbed suture in a porcine ex vivo model. Methods: Porcine flexor tendons were harvested and divided into 3 groups of 10 of varying suture material (3-0 PDS™, 3-0 V- V-Loc 180™, or 3-0 Stratafix™). A modified 4-strand cruciate technique was used to repair each tendon. Knotless repair was performed using barbed suture, whereas a buried 6-throw square knot was done using conventional suture. A servohydrolic tester was used for biomechanical testing of linear 2-mm gap resistance and maximum tensile strength. Results: No difference was found in 2-mm gap resistance among the 3 groups. No difference was found in ultimate tensile strength between V-Loc™ (76.0 ± 9.4 N) and Stratafix™ (68.1 ± 8.4 N) repairs, but the ultimate strength of the PDS™ control group (83.4 ± 10.0 N) was significantly higher than that of Stratafix™. Conclusions: Barbed (knotless) and nonbarbed suture repairs demonstrate equivalent 2-mm gap resistance. Stratafix™ repairs show slightly inferior performance to nonbarbed repairs in ultimate tensile strength, although this occurred at gap distances far beyond the 2-mm threshold for normal tendon gliding. Both barbed and nonbarbed 4-strand cruciate flexor tendon repairs may require peripheral repair to withstand physiologic loads.

A knotless bidirectional-barbed tendon repair is inferior to conventional 4-strand repairs in cyclic loading

We divided 21 flexor digitorum profundus tendons in the index, middle and ring fingers in seven cadaver hands into three groups. The tendons were cut in zone 2 and repaired using a 4-strand cruciate core suture repair with one of the following three materials in each group: (1) a knotless repair with a 2-0 bidirectional-barbed suture, which has similar tensile strength as a 4-0 non-barbed suture used in the other two groups; (2) a knotted locking repair with a non-barbed 4-0 conventional suture; and (3) a non-locking repair with a non-barbed 4-0 knotless suture. The repaired fingers were cyclically loaded through a simulated active range of motion to a 5 N load. We monitored and recorded the gap sizes at regular intervals during the test. The 2-0 bidirectional-barbed suture group and non-barbed suture groups developed gaps of 2.2 mm after 10 cycles and 2.4 mm after 20 cycles, respectively. Over 1000 cycles, the mean gaps were 3.2 mm in the 4-0 conventional suture group and 9.1 mm in the 2-0 bidirectional-barbed group. The tendons in the 2-0 bidirectional-barbed group gapped earlier, with statistically significant differences compared with those in the locking repair with a non-barbed 4-0 knotless suture group. The repair strength of the barbed suture technique was inferior to the cruciate repairs using a conventional 4-0 non-barbed suture tested in this cyclic-loading model.

LEVEL OF EVIDENCE

Level V.

Bone-Prosthesis Junction for Active Tendon Implants: A Biomechanical Comparison of 2 Fixation Techniques

PURPOSE

To study the biomechanical characteristics (percent stretch, stiffness, and ultimate load) of 2 distal fixation techniques for an active tendon implant used in the reconstruction of flexor tendons.

METHODS

We evaluated percent stretch after cyclical loading and at failure, stiffness during load-to-failure, and peak load of 28 bone-prosthesis junctions using cadaveric canine middle phalanges to study 2 fixation techniques: metal cleat and screw versus polyester cords secured with a knot.

RESULTS

The knot constructs displayed greater percent stretch during and following cyclical loading between 2 N and 50 N and at peak load. The screw construct showed greater stiffness from 50 N to 150 N during load-to-failure. Both fixation techniques failed at a mean peak load greater than 340 N.

CONCLUSIONS

Both fixation techniques for active tendon implants withstood loads seen with passive and active motion in the immediate postoperative period. Knot constructs displayed significant stretch during cyclical and load-to-failure testing, which would need to be compensated for during surgery. The screw constructs showed greater stiffness than the constructs secured with the surgeon's knot, but failure created an intra-articular fracture.

CLINICAL RELEVANCE

The results may aid the surgeon in choosing which fixation technique to use, during tensioning of cords, and in permitting active motion following surgery.

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.

Looped versus single-stranded flexor tendon repairs: a cadaveric mechanical study

PURPOSE

To compare the tensile properties of 4-strand modified Kessler flexor tendon repairs using a looped or single-stranded suture.

METHODS

We evaluated the mechanical properties of 4-strand Kessler zone II core suture repairs using either looped or single-stranded suture in human flexor digitorum profundus and flexor pollicis longus tendons. Forty repairs were performed on tendons from bilateral cadaveric hands: 20 matched tendons were divided into equal groups of 3-0 looped and 3-0 single-strand repairs and 20 additional matched tendons were divided into equal groups of 4-0 looped and 4-0 single-strand repairs. Repaired tendons were tested in uniaxial tension to failure to determine mechanical properties and failure modes. Data were analyzed to determine the effect of repair type (ie, looped vs single-stranded) for each suture caliber (ie, 3-0 and 4-0).

RESULTS

Single-strand repairs with 3-0 suture demonstrated a significantly greater maximum load to failure and a significantly higher force at 2-mm gap compared with repairs with looped 3-0 suture. All 8 looped repairs with 3-0 suture failed by suture pullout whereas 7 of 8 repairs with 3-0 single-stranded suture failed by suture breakage. The mechanical properties of looped versus single-stranded repairs with 4-0 caliber suture were not statistically different. Repairs with 4-0 caliber suture failed by suture breakage in 8 of 10 single-strand repairs and failed by suture pullout in 6 of 10 repairs with looped suture.

CONCLUSIONS

In a time-0 ex vivo human cadaveric core suture model, the mechanical properties of a 4-strand repair using 3-0 single-stranded suture were significantly better than the same 4-strand repair performed with looped suture.

CLINICAL RELEVANCE

Four-strand flexor tendon repairs with 3-0 suture are mechanically superior when performed with single-strand suture versus looped suture.

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.

Flexor tendon repair with a knotless, bidirectional barbed suture: an in vivo biomechanical analysis

PURPOSE

To compare and analyze biomechanical properties and histological characteristics of flexor tendons either repaired by a 4-strand modified Kessler technique or using barbed suture with a knotless repair technique in an in vivo model.

METHODS

A total of 25 chickens underwent surgical transection of the flexor digitorum profundus tendon followed by either a 4-strand Kessler repair or a knotless repair with barbed suture. Chickens were randomly assigned to 1 of 3 groups with various postoperative times to death. Harvested tendons were subjected to biomechanical testing or histologic analysis.

RESULTS

Harvested tendons revealed failures in 25% of knotless repairs (8 of 32) and 8% of 4-strand Kessler repairs (2 of 24). Biomechanical testing revealed no significant difference in tensile strength between 4-strand Kessler and barbed repairs; however, this lack of difference may be attributed to lower statistical power. We noted a trend toward a gradual decrease in strength over time for barbed repairs, whereas we noticed the opposite for the 4-strand Kessler repairs. Mode of failure during testing differed between repair types. The barbed repairs tended toward suture breakage as opposed to 4-strand Kessler repairs, which demonstrated suture pullout. Histological analysis identified no difference in the degree of inflammation or fibrosis; however, there was a vigorous foreign body reaction around the 4-strand Kessler repair and no such response around the barbed repairs.

CONCLUSIONS

In this model, knotless barbed repairs trended toward higher in vivo failure rates and biomechanical inferiority under physiologic conditions, with each repair technique differing in mode of failure and respective histologic reaction. We are unable to recommend the use of knotless barbed repair over the 4-strand modified Kessler technique.

CLINICAL RELEVANCE

For the repair techniques tested, surgeons should prefer standard Kessler repairs over the described knotless technique with barbed suture.

Barbed Sutures and Tendon Repair-a Review

INTRODUCTION

Traumatic tendon lacerations are a common problem encountered by hand surgeons worldwide. Although the use of barbed suture to repair tendon lacerations has gained theoretical popularity in recent years, there is little information available regarding the safety, efficacy, longevity, or complications encountered when used in tenorraphy. In this study, we review the available literature on the use of barbed suture in tendon repair.

METHODS

Studies conducted between 1980 and 2014 were identified using several databases, including EMBASE, SCOPUS, MEDLINE, and Web of Science. Keywords used to search for appropriate studies included the following: barbed, v loc, quill, tendon, tendon injuries, suture, tenorraphy, injury, and laceration, in various combinations.

RESULTS

Our initial literature search identified 47 articles, and 8 were deemed appropriate for review after applying our exclusion criteria. The data from each of the articles is reviewed for the following major categories:Maximum load to failureMode of failureLoad to 2-mm gapChange in cross-sectional areaType of repair.

CONCLUSIONS

Barbed suture tenorraphy has a myriad of theoretical advantages, supported by varying ex vivo studies, as compared to traditional techniques. However, due to the non-uniformity in current studies and the lack of available data in a live model, we are unable to argue for or against barbed suture tenorraphy. We believe our review provides the most in-depth analysis of barbed suture tenorraphy to date, illuminates the potential advantages of using barbed sutures, and highlights the need for further investigation into this technique.

Advances in the healing of flexor tendon injuries

The intrasynovial flexor tendons of the hand are critical for normal hand function. Injury to these tendons can result in absent finger flexion, and a subsequent loss of overall hand function. The surgical techniques used to repair these tendons have improved in the past few decades, as have the postoperative rehabilitation protocols. In spite of these advances, intrasynovial flexor tendon repairs continue to be plagued by postoperative scar formation, which limits tendon gliding and prevents a full functional recovery. This paper describes the current challenges of flexor tendon repair, and evaluates the most recent advances and strategies for achieving an excellent functional outcome.

Biomechanical analysis of flexor tendon repair using knotted Kessler and Bunnell techniques and the knotless Bunnell technique

PURPOSE

To evaluate a knotless Bunnell suture in flexor tendon repair.

METHODS

Eighty porcine flexor digitorum tendons were assigned to 4 different suture techniques. Group 1 was repaired using a modified 4-strand knotted Kessler suture and served as a control group. Group 2 was repaired using a 4-strand knotted Bunnell suture. Group 3 used a 4-strand knotless Bunnell suture. Group 4 used a 4-strand knotless Bunnell and knotless peripheral suture. Under static and cyclic testing we studied mode of failure, 2-mm gap formation force, displacement, and maximum load.

RESULTS

The 4-strand knotless Bunnell suture did not show a notable difference with regard to 2-mm gap formation force, displacement, or maximum load in comparison to the modified 4-strand knotted Kessler suture. Adding a knotless peripheral suture improved the repair by a significant reduction of gap formation and displacement and an increase in maximum load. The 4-strand knotted Bunnell showed the highest maximum load but also a considerable lower resistance to gap formation and major displacement.

CONCLUSIONS

Flexor tendon repair using a 4-strand knotless Bunnell suture showed similar tensile strength to a modified 4-strand knotted Kessler suture. Adding a knotless peripheral suture further improved the repair.

CLINICAL RELEVANCE

A complete knotless 4-strand Bunnell suture including a barbed core- and peripheral suture might be an option for flexor tendon reconstruction.

Proximal tendon-prosthesis junction for active tendon implants of the hand: a biomechanical comparison of 2 techniques

PURPOSE

To study the biomechanical characteristics (percent stretch, stiffness, and ultimate load) of 2 tendon-prosthesis techniques used to connect the proximal tendon stump to silicone active tendon implants used in reconstruction of flexor tendons.

METHODS

We evaluated percent stretch following cyclic loading and at failure, stiffness during load to failure, and ultimate load of 16 tendon-prosthesis junctions using cadaveric canine flexor digitorum profundus tendons to re-create 2 junction techniques: the tendon loop (TL) and the polyester weave (PW).

RESULTS

The TL junction showed greater percent stretch at a static load of 2 N, following 500 cycles of loading between 2 N and 50 N, and at peak load. The PW junction displayed greater stiffness from 50 to 150 N during load to failure. Both junctions failed at a mean ultimate load greater than 220 N.

CONCLUSIONS

The described proximal junction techniques for active tendon implants were strong enough to resist early active motion in the immediate postoperative period without significant elongation. The PW technique displayed greater stiffness and ultimate load compared with the TL.

CLINICAL RELEVANCE

Data on tendon-prosthesis characteristics of these 2 methods may aid the surgeon in choosing which junction technique to use, during surgical tensioning decisions, and in considering activity protocols after surgery. These data may also serve as a baseline for further investigations regarding active tendon implants.

A barbed suture repair for flexor tendons: a novel technique with no exposed barbs

Background:

Barbed suture technology has shown promise in flexor tendon repairs, as there is an even distribution of load and the need for a knot is eliminated. We propose that a quick and simple, novel, barbed technique without any exposed barbs on the tendon surface has comparable strength and a smaller cross-sectional area at the repair site than traditional methods of repair.

Methods:

Forty porcine flexor tendons were randomized to polybutester 4-strand barbed repair or to 4-strand Adelaide monofilament repair. The cross-sectional area was measured before and after repair. Biomechanical testing was carried out and 2-mm gap formation force, ultimate strength of repair, and method of failure were recorded.

Results:

The mean ultimate strength of the barbed repairs was 54.51 ± 17.9 while that of the Adelaide repairs was 53.17 ± 16.35. The mean 2-mm gap formation force for the barbed group was 44.71 ± 17.86 whereas that of the Adelaide group was 20.25 ± 4.99. The postrepair percentage change in cross-sectional area at the repair site for the Adelaide group and barbed group was 12.0 ± 2.3 and 4.6 ± 2.8, respectively.

Conclusions:

We demonstrated that a 4-strand knotless, barbed method attained comparable strength to that of the traditional Adelaide repair technique. The barbed method had a significantly reduced cross-sectional area at the repair site compared with the Adelaide group. The 2-mm gap formation force was less in the barbed group than the Adelaide group. Barbed repairs show promise for tendon repairs; this simple method warrants further study in an animal model.

Flexor tendon repairs: techniques, eponyms, and evidence

The evolution in surgical technique and suture technology has provided an abundance of options for flexor tendon repairs. Multiple biomechanical studies have attempted to identify the best surgical technique based on suture properties, technical modifications, and repair configurations. However, the burgeoning amount of research on flexor tendon repairs has made it difficult to follow, and no gold standard has been determined for the optimal repair algorithm. Therefore, it seems that repairs are usually chosen based on a combination of familiarity from training, popularity, and technical difficulty. We will discuss the advantages, disadvantages, and technical aspects of some of the most common core flexor tendon repairs in the literature. We will also highlight the nomenclature carried through the years, drawings of the repairs referred to by that nomenclature, and the data that support those repairs.

Suture material for flexor tendon repair: 3-0 V-Loc versus 3-0 Stratafix in a biomechanical comparison ex vivo

Background

Barbed suture material offers the possibility of knotless flexor tendon repair, as suggested in an increasing number of biomechanical studies. There are currently two different absorbable barbed suture products available, V-Loc™ and Stratafix™, and both have not been compared to each other with regard to flexor tendon repair. The purpose of this study was to evaluate both suture materials for primary stability under static and cyclic loading in a biomechanical ex vivo model.

Methods

Forty fresh porcine flexor digitorum profundus tendons were randomized in two groups. A four-strand modified Kessler suture technique was used to repair the tendon either with a 3–0 V-Loc™ or 3–0 Stratafix™ without a knot. Parameters of interest were mode of failure, 2-mm gap formation force, displacement, stiffness and maximum load under static and cyclic testing.

Results

The maximum load was 42.3 ± 7.2 for the Stratafix™ group and 50.7 ± 8.8 N for the V-Loc™ group. Thus, the ultimate tensile strength was significantly higher for V-Loc™ (p < 0.05). The 2-mm gap occurred at 24.8 ± 2.04 N in the Stratafix™ group in comparison to 26.5 ± 2.12 N in the V-Loc™ group (n.s.). Displacement was 2.65 ± 0.56 mm in the V-Loc™ group and 2.71 ± 0.59 mm in the Stratafix™ group (n.s.). Stiffness was 4.24 ± 0.68 (N/mm) in the V-Loc™ group and 3.85 ± 0.55 (N/mm) the Stratafix™ group (n.s.). Those measured differences were not significant.

Conclusion

V-Loc™ demonstrates a higher maximum load in tendon reconstruction. The differences in 2-mm gap formation force, displacement and stiffness were not significant. Hereby, the V-Loc™ has an advantage when used as unidirectional barbed suture for knotless flexor tendon repair.

Evidence-based medicine: Flexor tendon repair

LEARNING OBJECTIVES

After studying this article, the participant should be able to: (1) Describe and apply the current evidence-based treatment of acute flexor tendon injuries. (2) Compare and contrast the current postoperative therapy regimens following repair of flexor tendons. (3) Apply an evidence-based decision-making process for suture techniques of flexor tendon injuries.

SUMMARY

Flexor tendon repair remains a challenge for hand surgeons to reliably obtain excellent results. Surgical decisions should rely on the surgeon's experience, outcome studies, and direct evidence. This review is a compilation of the evidence from the literature on optimizing outcomes for flexor tendon repair.

Biomechanical evaluation of a knotless barbed suture repair in a human Achilles tendon rupture model

BACKGROUND

Knotless barbed sutures are seeing more common use in wound closures and small tendon repairs. The purpose of this study was to evaluate the strength and resistance to gap formation of these sutures in larger tendons, such as the Achilles, compared with conventional repair.

METHODS

Six matched pairs of fresh-frozen human cadaver Achilles tendons were transected to simulate a rupture. Six tendons were repaired using a double Bunnell over-the-top technique with Fiberwire, and the matched pairs were repaired using a double Bunnell knotless technique with barbed suture. The tendons were tested to failure and stiffness, peak failure load, percentage elongation, load at initial gap and load at 5-mm gap (clinical failure) were compared.

RESULTS

The mean peak failure load for the Fiberwire group (459 N) was significantly higher (P = .029) compared with the barbed suture group (184 N). Percentage elongation at peak load was significantly lower in the barbed suture group (P = .014), as was percentage elongation at initial gapping (P = .007) and percent elongation at 5 mm of gapping (P = .004).

CONCLUSION

While the knotless barbed suture is attractive for its design and resistance to gap formation, low failure loads compared with conventional suture are concerning for large tendon repairs.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Bench testing.

Enhanced spinal fusion using a biodegradable porous mesh container in a rat posterolateral spinal fusion model

BACKGROUND CONTEXT

Posterolateral fusion (PLF) with an autogenous iliac bone graft is the most common procedure for treating various lumbar spinal diseases. However, the limited success and associated morbidity from an iliac crest graft demands new biologically competent graft enhancers or substitutes.

PURPOSE

To investigate the feasibility of tubular mesh container made of bioabsorbable sutures (poly-1,4-dioxane-2-one, PDO) for spinal fusion.

STUDY DESIGN

Experimental animal study.

METHODS

A biodegradable PDO tubular mesh container was used to contain small pieces of bone grafts. Twenty Sprague-Dawley male rats underwent PLF between L4 and L5 transverse processes with bilateral iliac grafts. Experimental animals were assigned into two different groups: autograft-only group (N=10) that underwent PLF with autograft-only or mesh container group (N=10) that underwent PLF with tubular mesh container filled with autogenous bone grafts. The rats were sacrificed at 8 weeks postoperatively, and the lumbar spines were removed. Spinal fusion was evaluated by manual palpation, microcomputed tomography, three-point bending test, and histological examination.

RESULTS

Solid fusion was achieved in all cases of the mesh container group, whereas the autograft-only group showed 60% of solid fusion. New bone mass was higher and more solidly fused in the mesh container group than the autograft-only group (p<.01). Volume of fusion mass and density of bone were significantly higher in the mesh container group (p<.05). In all cases, inflammatory response was minimal.

CONCLUSIONS

This study demonstrated that a tubular mesh container made of bioabsorbable suture is useful to hold small pieces of bone grafts and to enhance spinal fusion.

The effect of suture caliber and number of core suture strands on zone II flexor tendon repair: a study in human cadavers

PURPOSE

To compare the tensile properties of a 3-0, 4-strand flexor tendon repair with a 4-0, 4-strand repair and a 4-0, 8-strand repair.

METHODS

Following evaluation of the intrinsic material properties of the 2 core suture calibers most commonly used in tendon repair (3-0 and 4-0), we tested the mechanical properties of 40 cadaver flexor digitorum profundus tendons after zone II repair with 1 of 3 techniques: a 3-0, 4-strand core repair, a 4-0, 8-strand repair, or a 4-0, 4-strand repair. We compared results across suture caliber for the 2 sutures and across tendon repair methods.

RESULTS

Maximum load to failure of 3-0 polyfilament caprolactam suture was 49% greater than that of 4-0 polyfilament caprolactam suture. The cross-sectional area of 3-0 polyfilament caprolactam was 42% greater than that of 4-0 polyfilament caprolactam. The 4-0, 8-strand repair produced greater maximum load to failure when compared with the 2 4-strand techniques. Load at 2-mm gap, stiffness, and work to yield were significantly greater in the 4-0, 8-strand repair than in the 3-0, 4-strand repair.

CONCLUSIONS

In an ex vivo model, an 8-strand repair using 4-0 suture was 43% stronger than a 4-strand repair using 3-0 suture, despite the finding that 3-0 polyfilament caprolactam was 49% stronger than 4-0 polyfilament caprolactam. These results suggest that, although larger-caliber suture has superior tensile properties, the number of core suture strands across a repair site has an important effect on time zero, ex vivo flexor tendon repair strength.

CLINICAL RELEVANCE

Surgeons should consider using techniques that prioritize multistrand core suture repair over an increase in suture caliber.

Performance of a knotless four-strand flexor tendon repair with a unidirectional barbed suture device: a dynamic ex vivo comparison

With increased numbers of reports using barbed sutures for tendon repairs we felt the need to design a specific tendon repair method to draw the best utility from these materials. We split 30 sheep deep flexor tendons in two groups of 15 tendons. One group was repaired with a new four-strand barbed suture repair method without knot. The other group was repaired with a conventional four-strand cross-locked cruciate repair method (Adelaide repair) with knot. Dynamic testing (3-30 N for 250 cycles) and additional static pull to failure was performed to investigate gap formation and final failure forces. The barbed suture repair group showed higher resistance to gap formation throughout the test. Additionally final failure force was higher for the barbed suture group compared with the conventional repair group. When used appropriately, barbed suture materials could be beneficial to use in tendon surgery, especially with regard to early loading of the repair site and gap formation.

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.

A nitinol based flexor tendon fixation device: gapping and tensile strength measurements in cadaver flexor tendon

In this study, a new nitinol based fixation device was investigated for use in repairing severed digital flexor tendons. The device, composed of superelastic nitinol, is tubular in shape with inward facing tines for gripping tissue. Its cellular structure was designed such that it has a large effective Poisson's ratio, which facilitates a “finger trap” effect. This allows for reduced tendon compression during a resting state (to permit vascular perfusion) and increased compression during loading (to drive the tines into the tissue for gripping). To test the feasibility of using this device for flexor tendon repair, it was tested on cadaver flexor digitorum profundus tendons. The tendons were excised, cut in the region corresponding to a zone II laceration, and repaired using the device. The device was easy to install and did not prevent the tendon from bending. Constant strain rate tensile testing revealed a mean tensile strength of 57.6 ± 7.7 N, with a force of 53.2 ± 7.8 N at a 2 mm gap. This exceeds the suggested primary repair strength of 45 N, which has been proposed as the necessary strength for enabling early mobilization. Although considerable future studies will be needed to determine the suitability of the new repair device for clinical use, this study demonstrates the feasibility of utilizing a tubular, nitinol repair device for flexor tendon fixation.

Biomechanical analysis of knotless flexor tendon repair using large-diameter unidirection barbed suture

PURPOSE

In traditional flexor tendon repairs, suture knots can be sites of weakness, impair tendon healing, stimulate an inflammatory response, and increase the bulk of the tendon repair. Because of this, there has been an increased interest in knotless flexor tendon repair using barbed suture. Since knots are not required, it may be possible to increase the strength of the tendon repair by using a large-diameter barbed suture. The purpose of this study was to biomechanically compare a traditional four-strand tendon repair using 3-0 braided polyester with a similar knotless four-strand tendon repair using 0 unidirectional barbed suture.

METHODS

Twenty-two matched cadaveric flexor digitorum profundus tendons were lacerated and assigned to repair by a four-strand modified Kirchmayr-Kessler technique using 3-0 braided polyester (n = 11) or knotless four-strand modified Kirchmayr-Kessler repair using 0 unidirectional barbed suture (n = 11). Repaired tendons were linearly distracted to failure at 20 mm/min after 1 N preload. Maximum load and load at 2-mm gap formation were recorded. Maximum load and load at 2-mm gap formation were compared with the Student's t test, and p values ≤ 0.05 were considered significant.

RESULTS

The mean maximum load of the barbed, knotless suture repair was higher than that of the traditional repair (52 vs. 42 N). There was no difference between the two groups in the mean load required to produce a 2-mm gap.

CONCLUSIONS

The four-strand knotless tendon repairs using a large-diameter unidirectional barbed suture were stronger than the traditional four-strand repairs using 3-0 braided polyester, and had similar 2-mm gap resistance.

Current practice of primary flexor tendon repair: a global view

In this article, a group of international leaders in tendon surgery of the hand provide details of their current methods of primary flexor tendon repair. They are from recognized hand centers around the world, from which major contributions to the development of methods for flexor tendon repair have come over the past 2 decades. Changes made since the early 1990s regarding surgical methods and postoperative care for the flexor tendon repair are also discussed. Current practice methods used in the leading hand centers are summarized, and key points in providing the best possible clinical outcomes are outlined.

Tensile strength of flexor tendon repair using barbed suture material in a dynamic ex vivo model

The purpose of this study was to compare two sutures; a knotted polydioxane with a knotless barbed in a 4-strand Kirchmayr-Kessler suture technique. Human flexor digitorum tendons were separated into four groups. Group 1 - polydioxane; Group 2 - barbed suture; Group 3 and 4 - same as group 1 and 2 with an additional peripheral running suture. In each group the repaired tendons were subjected to linear and cyclical loads. No difference in maximum tensile strength after linear and cyclical force could be detected between the knotted polydioxane suture and the knotless barbed suture. On linear force tests an additional circumferential repair increased the maximum tensile strength of both sutures. Cyclical force loading did not lead to a reduction of maximum strength. Following linear and cyclical loading the 4-strand barbed suture achieved maximum tensile strengths comparable to the 4-strand repair using the polydioxane suture. Barbed suture repair may offer the advantage of knotless suture techniques.