Comparison of a multifilament stainless steel suture with FiberWire for flexor tendon repairs--an in vitro biomechanical study

Influence of the direction of suture strands on the tensile strength after flexor tendon repairs

We assessed the influence of different directions of suture strands using the double Tsuge repair on the resistance to gap formation and mode of failure. In total, 25 porcine flexor digitorum profundus tendons were split into two groups. One group was repaired using a conventional double Tsuge suture created by two bands of looped suture placed longitudinally parallel (parallel method), and the other group was repaired using a new technique comprising two bands of looped suture placed in a crossed fashion in the anterior and posterior half of the tendon (cruciate method). The repaired tendons were subjected to linear, non-cyclic load-to-failure tensile testing. The cruciate method had a significantly higher mean load at a 2-mm gap tensile load (29.7 N [SD, 8.3]) than the parallel method (21.6 N [SD, 4.9]) and failed significantly more often due to suture pull-out. The direction of a core suture and its location within the tendon affect both gap resistance and the mode of failure of repair when using the double Tsuge suture technique, with a cruciate configuration achieving a greater gap resistance than a parallel one.

[Current Trends in Flexor Tendon Surgery: Results of a National Online Survey]

Within the last 50 years, there has been a change in trend in flexor tendon surgery. After the introduction of the 2-strand technique, the 4-strand technique was propagated in the 1990s. In order to obtain a status quo of which technique is used in Germany and if the gold standard of the 4-strand suture has changed in favour of a 6-strand suture, we conducted an online survey among members of the DGH ("Deutsche Gesellschaft für Handchirurgie", German Society for Hand Surgery) on the suture technique of flexor tendon injuries zone 2.

MATERIAL AND METHODS

An online survey was conducted and sent out by email to all DGH members. The questionnaire included 7 questions. Participants accessed the survey via a link.

RESULTS

155 hand surgeons from Germany participated in the survey. All of them answered the questionnaire in full and all questionnaires were included in the evaluation. The main question of how many strands are currently used for core suturing was answered as follows: 21% (n=32) of the 155 participants (TN) stated that they use a 2-strand suture, 53% used (n=82) a 4-strand suture and 10% used a 6-strand suture. Regarding techniques, 81 TN used the Kirchmayr-Kessler technique or a modification of it, 9 TN used the M-Tang technique, and 15 TN indicated "other technique". The question about the application of an epitendinous suture was overwhelmingly answered with "yes". Here, 98.2% agreed. Only with regard to the suture material, different opinions were found. 68% (n=106) use an absorbable monofilament suture (such as PDS). Just under a quarter (23%, n=36) use a non-absorbable monofilament suture (such as Prolene).

CONCLUSION

Flexor tendon surgery has changed considerably due to intensive advances in research during the last decades. It was interesting to note in our survey that German hand surgeons have adapted their suture technique within the last years based on the results of the literature. Our results clearly show that convincing scientific data has an influence on the choice of surgical technique and that discussions about new techniques, e. g. in the context of annual meetings, may well stimulate the auditorium to rethink.

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.

Biomechanical Analysis of a New Eight-Strand Suture for Flexor Tendon Repair

Background The placement of multistrand sutures during flexor tendon repair requires complicated surgical skills; such suturing is difficult. We developed a new, simpler eight-strand suture, which we term the Yoshizu cross-lock. This reduces the numbers of suture passages through the tendons, as well as the numbers of knots.

Methods Fourteen porcine flexor tendons were transected and repaired using the Yoshizu cross-lock system; no peripheral sutures were placed. Our system is a modification of the published, exposed cross-lock repair method that employs a 4–0 monofilament nylon two-strand line and two needles. The repaired tendons were subjected to linear, noncyclic load-to-failure tensile testing. The initial gap, the 2-mm gap force, and the ultimate strength were measured.

Results The initial gap force was 12.6 ± 5.6 Newtons (N), the 2-mm gap force was 33.9 ± 10.9 N, and the ultimate strength was 70.1 ± 17.0 N. All tendons subjected to Yoshizu cross-lock repair failed due to suture rupture rather than pullout.

Conclusions Our biomechanical study revealed that Yoshizu cross-lock repair had sufficient tensile strength but was associated with wide variation in the 2-mm gap load (standard deviation = 10.9 N). This study is clinically relevant, showing that the Yoshizu cross-lock repair combined with peripheral suturing may allow a repaired flexor tendon to withstand the stresses encountered during early active mobilization. This simple eight-strand technique will be particularly useful to surgeons who commonly employ the cross-lock stitch for primary flexor tendon repair following early mobilization.

Polymer-Based Constructs for Flexor Tendon Repair: A Review

A flexor tendon injury is acquired fast and is common for athletes, construction workers, and military personnel among others, treated in the emergency department. However, the healing of injured flexor tendons is stretched over a long period of up to 12 weeks, therefore, remaining a significant clinical problem. Postoperative complications, arising after traditional tendon repair strategies, include adhesion and tendon scar tissue formation, insufficient mechanical strength for early active mobilization, and infections. Various researchers have tried to develop innovative strategies for developing a polymer-based construct that minimalizes these postoperative complications, yet none are routinely used in clinical practice. Understanding the role such constructs play in tendon repair should enable a more targeted approach. This review mainly describes the polymer-based constructs that show promising results in solving these complications, in the hope that one day these will be used as a routine practice in flexor tendon repair, increasing the well-being of the patients. In addition, the review also focuses on the incorporation of active compounds in these constructs, to provide an enhanced healing environment for the flexor tendon.

Flexor tendon injuries: Repair & Rehabilitation

Flexor tendon injuries are common and occur mostly by penetrating trauma. Suspected flexor tendon injuries require a thorough clinical assessment and often are not isolated injuries. A detailed understanding of flexor tendon anatomy and spatial relationships is essential, especially when repairing multi-tendon injuries. Principles of flexor tendon repair include a strong suture construct, minimising gap formation between tendon ends, preserving tendon blood supply and providing a smooth repair interface. Moreover, adequate exposure of the zone of injury using full-thickness skin flaps and preservation of neurovascular and pulley structures is essential. In this article an overview of contemporary management strategies is presented. Today's hand surgeons and therapists can choose from a variety of treatment options when managing these important and potentially life-changing injuries.

Asymmetric 6-Strand Flexor Tendon Repair - Biomechanical Analysis Using Barbed Suture

Background: This study investigates the biomechanical performance of the Asymmetric flexor tendon repair technique using barbed suture. The Asymmetric repair technique using monofilament nylon suture was previously reported to have a higher tensile strength than the modified Lim-Tsai repair technique, but its repair stiffness and load to gap force were significantly lower. There is hence an unmet need to improve this technique and the substitution of nylon suture with barbed sutures may be the solution. Methods: Two groups consisting of 10 porcine tendons each were repaired with the six-strand Asymmetric repair technique using V-Loc^® 3-0 and Supramid^® 4-0 respectively. The repairs were subjected to a mechanical tester for static testing. The ultimate tensile strength, load to 2 mm gap force, repair stiffness, time taken to complete a repair and failure mechanism of the repairs were recorded and analyzed. Results: All the repairs using V-Loc^® 3-0 sutures had significantly higher median values of ultimate tensile strength (64.1 N; 56.9 N), load to 2 mm gap force (39.2 N; 19.7 N), repair stiffness (6.4 N/mm; 4.7 N/mm) and time taken to complete a repair (9.4 mins; 7.7 mins). All the repairs using V-Loc^® sutures failed by suture breakage while 80% of repairs using Supramid^® sutures failed by suture pullout. Conclusions: The use of the barbed sutures in the Asymmetric repair technique, whilst more time consuming, has shown promising improvement to its biomechanical performance (i.e. better ultimate tensile strength, stiffness and resistance to gap formation).

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.

Comparison of Flexor Tendon Suture Techniques Including 1 Using 10 Strands

PURPOSE

To compare mechanical properties of a multistrand suture technique for flexor tendon repair with those of conventional suture methods through biomechanical and clinical studies.

METHODS

We describe a multistrand suture technique that is readily expandable from 6 to 10 strands of core suture. For biomechanical evaluation, 60 porcine flexor tendons were repaired using 1 of the following 6 suture techniques: Kessler (2-strand), locking cruciate (4-strand), Lim/Tsai's 6-strand, and our modified techniques (6-, 8-, or 10-strand). Structural properties of each tenorrhaphy were determined through tensile testing (ultimate failure load and force at 2-mm gap formation). Clinically we repaired 25 flexor tendons using the described 10-strand technique in zones I and II. Final follow-up results were evaluated according to the criteria of Strickland and Glogovac.

RESULTS

In the biomechanical study, tensile properties were strongly affected by repair technique; tendons in the 10-strand group had approximately 106%, 66%, and 39% increased ultimate load to failure (average, 87 N) compared with those in the 4-, 6-, and 8-strand groups, respectively. Tendons in the 10-strand group withstood higher 2-mm gap formation forces (average, 41 N) than those with other suture methods (4-strand, 26 N; 6-strand, 27 N; and 8-strand, 33 N). Clinically, we obtained 21 excellent, 2 good, and 2 fair outcomes after a mean of 16 months (range, 6-53 mo) of follow-up. No patients experienced poor results or rupture.

CONCLUSIONS

The 10-strand suture repair technique not only increased ultimate strength and force at the 2-mm gap formation compared with conventional suture methods, it also showed good clinical outcomes. This multistrand suture technique can greatly increase the gap resistance of surgical repair, facilitating early mobilization of the affected digit.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Evidence-based flexor tendon repair

The goal of flexor tendon repair is to achieve normal range of motion of the finger or thumb. The surgical approach depends on the level of injury. Multistrand core suture repairs are recommended for primary flexor tendon repair. It is evident that at least 4 strands are required to an initiate and active range of motion protocol. The epitendinous suture can also increase the strength of the repair. Careful attention to the post-operative therapy regiment is critical to a successful repair.

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.

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.

Flexor tendon repair, rehabilitation, and reconstruction

BACKGROUND

Flexor tendon injury is a common problem that plastic surgeons are called on to treat. Despite their common nature, they present a challenge, not necessarily in the surgical treatment per se but in the ability to achieve a "normal" finger as the end result. Because of the difficulty in attaining good outcomes, much continues to be studied and written about flexor tendon injury.

METHODS

The current literature on flexor tendon repair, rehabilitation, and reconstruction is reviewed.

RESULTS

Aspects reviewed include type of anesthesia, suture material and configuration, repairs in the different flexor tendon zones, types of tendon rehabilitation, complications of flexor tendon surgery, and flexor tendon reconstruction.

CONCLUSION

This review provides an update on the current standards in the treatment of flexor tendon injury.

Flexor tendon repair: a comparative study between a knotless barbed suture repair and a traditional four-strand monofilament suture repair

We compared the tensile strength of a novel knotless barbed suture method with a traditional four-strand Adelaide technique for flexor tendon repairs. Forty fresh porcine flexor tendons were transected and randomly assigned to one of the repair groups before repair. Biomechanical testing demonstrated that the tensile strengths between both tendon groups were very similar. However, less force was required to create a 2 mm gap in the four-strand repair method compared with the knotless barbed technique. There was a significant reduction in the cross-sectional area in the barbed suture group after repair compared with the Adelaide group. This would create better gliding within the pulley system in vivo and could decrease gapping and tendon rupture.

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.