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

Open and Percutaneous Approaches Have Similar Biomechanical Results for Primary Midsubstance Achilles Tendon Repair: A Meta-analysis

Purpose

To evaluate the biomechanical properties of open versus percutaneous Achilles tendon repair.

Methods

A systematic review of original research articles was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. To qualify for study inclusion, articles were required to be published in English, use a laboratory design using either human or animal tissue, and directly compare the biomechanical properties of open Achilles repair using a Krackow or Kessler technique with percutaneous repair using either a locking or nonlocking suture construct. The biomechanical outcomes evaluated were displacement (millimeters) and load to failure (Newtons).

Results

Twelve studies met inclusion criteria, including 234 specimens (open: 97, percutaneous locking: 73; percutaneous nonlocking: 64) that underwent primary midsubstance Achilles tendon repair. Pooled analysis demonstrated no statistically significant difference in displacement (P = .240) or load to failure (P = .912) between the open and percutaneous techniques. Among the percutaneous approaches, there was no difference in displacement (P = .109) between the locking and nonlocking tendon repair systems.

Conclusions

The results of this study suggest that both open and percutaneous techniques are biomechanically viable approaches for primary midsubstance Achilles tendon repair.

Clinical Relevance

In clinical studies, similar rerupture rates have been observed after open or percutaneous Achilles tendon repair. It may be beneficial for surgeons to understand whether biomechanical differences exist between these repair techniques.

General Principles of Flexor Tendon Repair

Flexor tendon repair techniques and rehabilitation have advanced tremendously in the past 50 years. However, the attributes of the ideal tendon repair articulated by Dr Strickland in 1995 hold true today. The ideal repair requires sutures easily placed in the tendon, secure suture knots, a smooth juncture of the tendon ends, minimal gapping, least interference with tendon vascularity, and sufficient strength throughout healing. When accomplished, the modern flexor tendon repair is a stout repair, sufficient for early mobilization and intrinsic tendon healing.

A discrete shear lag model of the mechanics of hitchhiker plants, and its prospective application to tendon-to-bone repair

Tendon-to-bone repairs often fail when sutures pull through tendon, like a wire through cheese. Repair strength is maximized when loads are balanced equally among all sutures, relative to the pullout resistance of the tendon and the strength of the sutures. This problem of balancing loads across multiple, discrete attachment sites has been solved in nature by hitchhiker plants that proliferate by adhering relatively stiff fruit to relatively soft fur and fabrics through arrays of hooks. We, therefore, studied the fruits of such a plant, Harpagonella palmeri , and developed a discrete shear lag analysis of the force distributions in H. palmeri 's linear arrays of long, slender hooks of varied lengths and spacing. Results suggested that strategies were used by the plant to distribute loads, including variations in the spacing and stiffnesses of hooks that serve to equalize forces over attachment sites. When applying these models to suturing schemes for surgical reattachment of tendon to bone, results suggested that strategies exhibited by H. palmeri show promise for balancing forces over sutures, potentially doubling repair strength relative to what could be achieved with a uniform suture distribution. Results suggest a potential pathway for strengthening surgical repairs, and more broadly for optimizing fasteners for bi-material attachment.

Comparison the Range of Motion Following Early Versus Late Active Mobilization after Repairing Surgery on Flexor Tendon Injury in the Zone II: A Randomized Clinical Trial

Background

Early or delayed mobilization of limb after flexor tendon rupture repairing has an effect on postoperative outcomes, however it is not yet clear whether early or late organ mobilization leads to more likelihood of recovery. We aimed to assess the effects of early and late active limb mobilization through rehabilitation after surgery on the range of motion and hand recovery.

Methods

This randomized clinical study was performed in Sina Hospital, Tehran, Iran in 2022 on 80 patients with flexor tendon damage in the zone II, who underwent reconstructive surgery of superficial and deep tendons. Patients were randomly (using random number table) divided into two groups that for one group, rehabilitation was done early (starting after three days, n = 53) and for the other group, rehabilitation was done late (starting after three weeks, n = 27). The patients were examined postoperatively and following occupational therapy and the range of motion of their involved joints was calculated.

Results

The means PIP extension Lag, PIP active flexion, DIP extension Lag, DIP active flexion and total active motion were all significantly higher in those patients planned for early mobilization as compared to those who considered for late mobilization(P=0.031). Such a significant difference was also revealed adjusting baseline parameters.

Conclusion

Compared to the delayed start of hand flexor tendon mobility, the early start of these activities is associated with a much greater improvement in the movement function of this tendon.

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 Modified Kessler and McLarney Techniques in Zone II Flexor Tendon Repair

Introduction

Hand injuries are common in the routine practice of any upper limb surgeon. The laceration of the flexor tendons can engage the functional prognosis of the hand. Hence, there exist a multitude pf suturing techniques whose goal is to have a solid repair, allowing an early rehabilitation. Our study aims at comparing the functional results after flexor tendon repairs in zone II using two different techniques, modified Kessler technique and McLarney technique.

Methods

Our study included 42 patients, divided into two groups, one having benefited from the modified Kessler technique and the other from the McLarney technique. The modified Strickland classification was used to compare the functional results at six months after surgery of the two techniques.

Results

Our study showed a better post-operative functional outcome with a lower risk of post-operative rupture in patients operated with the McLarney four-strand technique compared to patients operated with the modified Kessler two-strand technique.

Conclusion

Hand wounds in zone II remain a therapeutic challenge for any orthopedic surgeon due to the multiplicity of factors involved in the prognosis, in particular the type of suture. The suture with more than two strands has proven its effectiveness and its reproducibility, making it possible to find the balance sought by the surgeon, namely a suture that is not cumbersome, easy and quick to perform, and strong enough to start early rehabilitation.

Initial Experience with the PONTiS Tendon Repair System in Traumatic Upper Extremity Injuries

BACKGROUND

Tendon injuries of the upper extremity remain a common surgical condition requiring prompt intervention. We review our initial experience with the PONTiS flexor tendon repair system (PFRS) - a knotless, multifilament stainless steel crimp system.

METHODS

Consecutive patients undergoing repair by our plastic and orthopedic surgeons with the PFRS were reviewed from 2015-2017. Multivariate risk and Kaplan-Meier survival analyses were performed to assess risk factors associated with complications.

RESULTS

Eighty-one patients with mean follow up of 75 days (range 0 - 33 months) were identified. The most common demographics of our patients were right-handed (82.9%), male (71.4%), laborer (35.7%), sustaining laceration injuries (77.1%) at zone 2 (27.2%). There was an average of 3.7 tendon injuries per patient. Associated injuries included fractures (21.4%), arterial injuries (24.3%), and nerve injuries (61.4%). Thirteen (16.0%) patients developed complications: adhesions/contracture (4), rupture (2), flap ischemia (2), arterial thrombosis (1), wound dehiscence (1), tendon lag (1), and erosion of the PFRS through soft-tissue grafts (2). Multivariate analysis identified poor soft-tissue coverage (OR 9.990; p=0.043) and zone 2 involvement (OR 7.936; p=0.016) as risk factors, while epitendinous repairs (OR 0.096; p=0.010) were protective against complications.

CONCLUSIONS

The PFRS system is rapid and simple to deploy and advantageous especially in multiple traumatic tendon injuries. Compared to traditional suture repair, it has a comparable overall complication profile but superior rupture and tenolysis rates. We advise use with caution in cases with poor soft tissue coverage to minimize risks of extrusion and strongly recommend the use of epitendinous sutures concurrently to limit complications.

Investigation of the effects of two-, four-, six- and eight-strand suture repairs on the biomechanical properties of canine gastrocnemius tenorrhaphy constructs

OBJECTIVE

To determine the effects of 2-, 4-, 6- and 8-strand suture repairs on the biomechanical properties of canine gastrocnemius tenorrhaphy constructs in an ex vivo model.

SAMPLE

56 cadaveric gastrocnemius musculotendinous units from 28 adult large-breed dogs.

PROCEDURES

Tendons were randomly assigned to 4 repair groups (2-, 4-, 6- or 8-strand suture technique; n = 14/group). Following tenotomy, repairs were performed with the assigned number of strands of 2-0 polypropylene suture in a simple interrupted pattern. Biomechanical testing was performed. Yield, peak, and failure loads, the incidence of 1- and 3-mm gap formation, forces associated with gap formation, and failure modes were compared among groups.

RESULTS

Yield, peak, and failure forces differed significantly among groups, with significantly greater force required as the number of suture strands used for tendon repair increased. The force required to create a 1- or 3-mm gap between tendon ends also differed among groups and increased significantly with number of strands used. All constructs failed by mode of suture pull-through.

CONCLUSIONS AND CLINICAL RELEVANCE

Results indicated that increasing the number of suture strands crossing the repair site significantly increases the tensile strength of canine gastrocnemius tendon repair constructs and their resistance to gap formation. Future studies are needed to assess the effects of multistrand suture patterns on tendon glide function, blood supply, healing, and long-term clinical function in dogs to inform clinical decision-making.

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.

Evaluation of Hand Tendon Elastic Properties During Rehabilitation Through High-Frequency Ultrasound Shear Elastography

Tendon injuries lead to tendon stiffness, which impairs skeletal muscle movement. Most studies have focused on patellar or Achilles tendons by using ultrasound elastography. Only a few studies have measured the stiffness of hand tendons because their thickness is only 1-2 mm, rendering clinical ultrasound elastography unsuitable for mapping hand tendon stiffness. In this study, a high-frequency ultrasound shear elastography (HFUSE) system was proposed to map the shear wave velocity (SWV) of hand flexor tendons. A handheld vibration system that was coaxially mounted with an external vibrator on a high-frequency ultrasound (HFUS) array transducer allowed the operators to scan hand tendons freely. To quantify the performance of HFUSE, six parameters were comprehensively measured from homogeneous, two-sided, and three-sided gelatin phantom experiments: bias, precision, lateral resolution, contrast, contrast-to-noise ratio (CNR), and accuracy. HFUSE demonstrated an excellent resolution of [Formula: see text] to distinguish the local stiffness of thin phantom (thickness: 1.2 mm) without compromising bias, precision, contrast, CNR, and accuracy, which has been noted with previous systems. Human experiments involved four patients with hand tendon injuries who underwent ≥2 months of rehabilitation. Using HFUSE, two-dimensional SWV images of flexor tendons could be clearly mapped for healthy and injured tendons, respectively. The findings demonstrate that HFUSE can be a promising tool for evaluating the elastic properties of the injured hand tendon after surgery and during rehabilitation and thus help monitor progress.

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.

Effect of epitendinous suture caliber on the tensile strength of repaired canine flexor tendons

OBJECTIVE

To determine the effect of epitendinous suture (ES) caliber on the tensile strength of flexor tendon repairs in cadaveric specimens from dogs.

SAMPLE

60 cadaveric superficial digital flexor tendons (SDFTs) from 30 skeletally mature dogs.

PROCEDURES

Specimens were randomly assigned to 5 suture caliber groups (n = 12 SDFTs/group). After sharp transection, SDFTs were repaired by placement of a simple continuous circumferential ES created with size-0, 2-0, 3-0, 4-0, or 5-0 polypropylene suture. Constructs were preloaded to 2 N and load tested to failure. Loads at yield, peak, and failure and mode of failure were compared among groups by statistical methods.

RESULTS

Yield, peak, and failure loads for SDFT repair constructs were positively correlated with ES caliber and did not differ between the size-0 and 2-0 groups on pairwise comparisons. Yield load was significantly greater for size-0, 2-0, and 3-0 groups than for the 4-0 and 5-0 groups. Peak and failure loads were significantly greater for the size-0 and 2-0 groups than for the remaining groups. Most size-0 (12/12), 2-0 (12/12), and 3-0 (10/12) group constructs failed because of ES pull-through; several constructs in the 4-0 group (5/12) and most in the 5-0 group (11/12) failed because of ES breakage.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested size-0 and 2-0 sutures should be considered when placing an ES for flexor tendon repairs in dogs. However, in vivo studies are needed determine the effects of increasing ES caliber on clinical outcomes for dogs undergoing these procedures.

An ex vivo biomechanical comparison of two suture materials and two pattern combinations for equine superficial digital flexor tendon tenorrhaphy

OBJECTIVE

To compare biomechanical characteristics of three-loop pulley (3LP) pattern versus Bunnell technique (BT) using polydioxanone (PDS) suture; to determine the influence of polyester tape (PT) versus PDS on the BT for equine superficial digital flexor tendon (SDFT) tenorrhaphy; to compare BT with PT versus 3LP with PDS.

STUDY DESIGN

Ex vivo biomechanical study.

SAMPLE POPULATION

Forty equine forelimb SDFT.

METHODS

Two experiments were performed: (1) 10 SDFT pairs were repaired with 3LP or BT using PDS; (2) 10 SDFT pairs were repaired with PDS or PT using BT. Load at failure, mode of failure, load at 2 mm gap, and gap at failure were obtained using a material testing machine.

RESULTS

In experiment 1, 3LP + PDS₁ had higher loads at failure (p < .001) and at 2 mm gap (p < .001), and smaller gap at failure than BT + PDS₁ (p = .024). In experiment 2, BT + PT₂ had higher loads at failure (p < .001) and at 2 mm gap (p = .001), and larger gap at failure (p = .004) than the BT + PDS₂ . 3LP + PDS₁ and BT + PT₂ mostly failed by suture/implant pull-through while BT + PDS failed by suture breakage. BT + PT₂ had greater load (p = .035) and gap at failure (p < .001) than 3LP + PDS_1, with no difference in load at 2 mm gap (p = .14).

CONCLUSION

The use of BT may be justified over 3LP if combined with PT. However, the larger size of the PT required stab incisions in the tendon for placement and was subjectively more difficult to place than PDS.

CLINICAL SIGNIFICANCE

The BT + PT, although the strongest among the tested repairs, would only be able to withstand 12%-24% of the load encountered by the SDFT at walk.

Acute Achilles Tendon Ruptures

There is an ever-evolving debate about the best treatment option for Achilles tendon ruptures. There was a relative consensus that operative treatment yielded the best outcomes. Much of this is based on results in athletic populations. Conservative treatment was considered only for the elderly and those with very inactive lifestyles. There has been an evolution, however, with more surgeons utilizing an aggressive functional rehabilitation with conservative management. Surgical intervention still is the treatment of choice for elite-level athletes. The treatment of choice for patient populations other than elite athletes remains an individual choice between patient and physician.

Rehabilitation following surgery for flexor tendon injuries of the hand

BACKGROUND

Various rehabilitation treatments may be offered following surgery for flexor tendon injuries of the hand. Rehabilitation often includes a combination of an exercise regimen and an orthosis, plus other rehabilitation treatments, usually delivered together. The effectiveness of these interventions remains unclear.

OBJECTIVES

To assess the effects (benefits and harms) of different rehabilitation interventions after surgery for flexor tendon injuries of the hand.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, MEDLINE, Embase, two additional databases and two international trials registries, unrestricted by language. The last date of searches was 11 August 2020. We checked the reference lists of included studies and relevant systematic reviews.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs that compared any postoperative rehabilitation intervention with no intervention, control, placebo, or another postoperative rehabilitation intervention in individuals who have had surgery for flexor tendon injuries of the hand. Trials comparing different mobilisation regimens either with another mobilisation regimen or with a control were the main comparisons of interest. Our main outcomes of interest were patient-reported function, active range of motion of the fingers, and number of participants experiencing an adverse event.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, extracted data, assessed risk of bias and assessed the quality of the body of evidence for primary outcomes using the GRADE approach, according to standard Cochrane methodology.

MAIN RESULTS

We included 16 RCTs and one quasi-RCT, with a total of 1108 participants, mainly adults. Overall, the participants were aged between 7 and 72 years, and 74% were male. Studies mainly focused on flexor tendon injuries in zone II. The 17 studies were heterogeneous with respect to the types of rehabilitation treatments provided, intensity, duration of treatment and the treatment setting. Each trial tested one of 14 comparisons, eight of which were of different exercise regimens. The other trials examined the timing of return to unrestricted functional activities after surgery (one study); the use of external devices applied to the participant to facilitate mobilisation, such as an exoskeleton (one study) or continuous passive motion device (one study); modalities such as laser therapy (two studies) or ultrasound therapy (one study); and a motor imagery treatment (one study). No trials tested different types of orthoses; different orthosis wearing regimens, including duration; different timings for commencing mobilisation; different types of scar management; or different timings for commencing strengthening. Trials were generally at high risk of bias for one or more domains, including lack of blinding, incomplete outcome data and selective outcome reporting. Data pooling was limited to tendon rupture data in a three trial comparison. We rated the evidence available for all reported outcomes of all comparisons as very low-certainty evidence, which means that we have very little confidence in the estimates of effect. We present the findings from three exercise regimen comparisons, as these are commonly used in clinical current practice. Early active flexion plus controlled passive exercise regimen versus early controlled passive exercise regimen (modified Kleinert protocol) was compared in one trial of 53 participants with mainly zone II flexor tendon repairs. There is very low-certainty evidence of no clinically important difference between the two groups in patient-rated function or active finger range of motion at 6 or 12 months follow-up. There is very low-certainty evidence of little between-group difference in adverse events: there were 15 overall. All three tendon ruptures underwent secondary surgery. An active exercise regimen versus an immobilisation regimen for three weeks was compared in one trial reporting data for 84 participants with zone II flexor tendon repairs. The trial did not report on self-rated function, on range of movement during three to six months or numbers of participants experiencing adverse events. The very low-certainty evidence for poor (under one-quarter that of normal) range of finger movement at one to three years follow-up means we are uncertain of the finding of zero cases in the active group versus seven cases in the immobilisation regimen. The same uncertainty applies to the finding of little difference between the two groups in adverse events (5 tendon ruptures in the active group versus 10 probable scar adhesion in the immobilisation group) indicated for surgery. Place and hold exercise regimen performed within an orthosis versus a controlled passive regimen using rubber band traction was compared in three heterogeneous trials, which reported data for a maximum of 194 participants, with mainly zone II flexor tendon repairs. The trials did not report on range of movement during three to six months, or numbers of participants experiencing adverse events. There was very low-certainty evidence of no difference in self-rated function using the Disability of the Arm, Shoulder and Hand (DASH) functional assessment between the two groups at six months (one trial) or at 12 months (one trial). There is very low-certainty evidence from one trial of greater active finger range of motion at 12 months after place and hold. Secondary surgery data were not available; however, all seven recorded tendon ruptures would have required surgery. All the evidence for the other five exercise comparisons as well as those of the other six comparisons made by the included studies was incomplete and, where available, of very low-certainty.

AUTHORS' CONCLUSIONS

There is a lack of evidence from RCTs on most of the rehabilitation interventions used following surgery for flexor tendon injuries of the hand. The limited and very low-certainty evidence for all 14 comparisons examined in the 17 included studies means that we have very little confidence in the estimates of effect for all outcomes for which data were available for these comparisons. The dearth of evidence identified in this review points to the urgent need for sufficiently powered RCTs that examine key questions relating to the rehabilitation of these injuries. A consensus approach identifying these and establishing minimum study conduct and reporting criteria will be valuable. Our suggestions for future research are detailed in the review.

Effects of Different Core Suture Lengths on Tensile Strength of Multiple-Strand Sutures for Flexor Tendon Repair

Purpose

To compare 2 types of newly devised 8-strand quadruple-looped suture (QLS) techniques with a 6-strand triple-looped suture (TLS) technique; and to assess the effects of different core suture lengths (CSLs) (the length between 2 locking sites of a suture strand) within each suture row on tensile strength.

Methods

We repaired 24 flexor tendons from 12 rabbits using the TLS and QLS techniques, with equal CSL (QLS) or unequal CSL (unequal QLS) among each suture row. The QLS was composed of 4 looped sutures on the anterolateral and posterolateral aspects of the tendon. The cross-sectional area of the locking portion of each thread in the QLS was equal to that in the TLS. In the QLS technique, the CSL on each aspect of the tendon was 13 mm. In the unequal QLS technique, the CSL on each aspect of the tendon was 13 and 17 mm. The load at 1- and 2-mm gaps, the maximum load until the 3-mm gap, and the ultimate load were compared among the 3 techniques.

Results

The QLS was significantly stronger than the unequal QLS and the TLS for loads at 1-mm and 2-mm gaps, maximum load until 3-mm gap, and ultimate load. There was no significant difference between the unequal QLS and TLS techniques. The QLS technique showed an approximately 30% increase in gap resistance and ultimate strength compared with the TLS technique.

Conclusions

The QLS technique showed an estimated increase in tensile strength proportional to the number of suture strands compared with the TLS technique. Our study suggests that a consistent CSL in each suture row provides the highest strength in multistrand sutures consisting of the same configuration of suture rows.

Clinical relevance

The QLS technique may reduce the risk for tendon rupture associated with early active mobilization after flexor tendon repair.

Biomechanical Analysis of Zone 2 Flexor Tendon Repair With a Coupler Device Versus Locking Cruciate Core Suture

PURPOSE

To compare flexor tendon repair strength and speed between a tendon coupler and a standard-core suture in a cadaver model.

METHODS

In 5 matched-pair fresh cadaver hands, we cut the flexor digitorum profundus tendon of each finger in zone 2 and assigned 20 tendons to both the coupler and the suture groups. Coupler repair was with low-profile stainless steel staple plates in each tendon stump, bridged by polyethylene thread. Suture repair was performed using an 8-strand locking-cruciate technique with 4-0 looped, multifilament, polyamide suture. One surgeon with the Subspecialty Certificate in Surgery of the Hand performed all repairs. Via a load generator, each flexor digitorum profundus was loaded at 5 to 10 N and cycled through flexion just short of tip-to-palm and full extension at 0.2 Hz for 2,000 cycles to simulate 6 weeks of rehabilitation. We recorded repair gapping at predetermined cycle intervals. Our primary outcome was repair gapping at 2,000 cycles. Tendons that had not catastrophically failed by 2,000 cycles were loaded to failure on a servohydraulic frame at 1 mm/s.

RESULTS

Tendon repair gapping was similar between coupled and sutured tendons at 2,000 cycles. Tendons repaired with the coupler had higher residual load to failure than sutured tendons. Mean coupler repair time was 4 times faster than suture repair.

CONCLUSIONS

Zone 2 flexor repair with a coupler withstood simulated early active motion in fresh cadavers. Residual load to failure and repair speed were better with the coupler.

CLINICAL RELEVANCE

This tendon coupler may eventually be an option for strong, reproducible, rapid flexor tendon repair.

Rupture Rates Between 2-Strand and 4-Strand Flexor Tendon Repairs: Is Less More?

The purpose of this study was to explore the difference in clinical outcome of 2-strand and 4-strand flexor tendon repairs in a single unit in adult population. A total of 109 complete divisions of a single flexor tendon were analyzed from 2016 to 2018 retrospectively. Thirty flexor tendons were repaired with 2-strand and 79 tendons were repaired with 4-strand technique. There was no significant difference in the complication rate including rupture, infection, and adhesions. These results support that 4-strand is not superior than 2-strand and that lower volume type of repair would be preferable.

Comparison of surgical trends in zone 2 flexor tendon repair between Turkish and international surgeons

Objectives

The aim of this study was to evaluate Turkish trends in zone 2 flexor repair with regards to surgical technique, suture materials, anesthesia and post-operative rehabilitation and compare this with international surgeons by modifying Gibson's survey.

Methods

A printed and online survey consisting of 19 questions modified from Gibson's survey was sent to 590 Turkish and international surgeons. The surgeon's years in practice, province of practice, residency type, number of zone 2 flexor tendon repairs done in a year, preferred surgical technique, suture material, complications and postoperative protocols were asked to the respondents.

Results

A total of 194 surgeons completed the survey (a 25% response rate). Of those who completed the survey, 91 were international (mostly from far eastern countries) and 103 were Turkish surgeons. Years in practice and educational background had influence on the decision-making. There were differences between the Turkish and international surgeons in the core and epitendinous suture thickness preference and flexor tendon sheath repair. There was a statistically significant relationship between the province of practice and the use of WALANT (Wide awake local anesthesia no tourniquet) (p < 0.05). While the majority of respondents who preferred postoperative early passive motion protocol were from Turkey (61.5%), the majority of respondents who preferred early active motion protocol were practicing abroad (73.9%).

Conclusion

Despite some variations the surgeons involved in this study follow to a large extent the current literature.

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.

Flexor tendon injuries

Flexor tendon injuries have constituted a large portion of the literature in hand surgery over many years. Yet many controversies remain and the techniques of surgery and therapy are still evolving. The anatomical and finer technical considerations involved in treating these injuries have been put forth and discussed in detail including the rehabilitation following the flexor tendon repair. The authors consider, recognition and mastery of these facts form the foundation for a successful flexor tendon repair. The trend is now towards multiple strand core sutures followed by early active mobilization. However, the rehabilitation process appears to be one of the major determinant of the success following a flexor tendon repair. Early mobilization is essential for all the flexor tendon repairs as it is proved to improve the quality of the repaired tendon. The art of achieving the harmony between a stronger repair and unhindered gliding of the repair site through the narrow flexor tendon sheath simultaneously can be mastered with practice added to the knowledge of the basic principles.

The effect of modified locking methods and suture materials on Zone II flexor tendon repair-An ex vivo study

The failure rate of intrasynovial tendon repair is high due to substantial elongation at the repair site and to the development of adhesions between the tendon’s surface and the surrounding digital sheath. To minimize these complications, we sought to reduce the incidence of gapping and to facilitate the initiation of early motion by improving the time zero structural properties of repair. The Winters-Gelberman 8-strand repair technique was modified by adding surface lock loops and by using Fiberwire suture material. Forty-eight canine flexor digitorum profundus tendons were transected and repaired with one of three 8-strand techniques (Pennington modified Kessler, half hitch loops, or surface locking Kessler) using either 3–0 Supramid or 4–0 Fiberwire suture. Biomechanical testing was performed to determine the physiologic and failure mode properties of the repairs. The surface locking Kessler technique improved repair maximum load, load necessary to create a 2 mm repair site gap, and yield force compared to the modified Kessler and half hitch loop techniques. Fiberwire suture improved maximum load, the load necessary to create a 2 mm repair site gap, stiffness, and yield force compared to Supramid suture. Failure occurred by both suture pull out and by suture breakage in the modified Kessler, Supramid suture repair group. Failure occurred consistently by suture breakage in the surface locking Kessler, Supramid suture repair group. These results reveal that a novel locking Kessler repair is significantly stronger than the current state-of-the art flexor tendon suture repair technique. The use of a surface locking Kessler technique with Fiberwire suture markedly improves the mechanical properties of intrasynovial tendon repair by reducing the risk of post-operative gapping and rupture.

Results of 4-strand modified Kessler core suture and epitendinous interlocking suture followed by modified Kleinert protocol for flexor tendon repairs in Zone 2

Objective

There has been no consensus in literature for the ideal flexor tendon repair technique. The results of zone 2 flexor tendon lacerations repaired primarily by 4 strand Modified Kessler core suture and epitendinous interlocking suture technique followed by Modified Kleinert protocol were investigated.

Methods

128 fingers of 89 patients who had flexor tendon laceration in zone 2 built the working group. Functional outcomes were evaluated using the Strickland formula. A statistical analysis was made between Strickland scores and some parameters such as age, gender, follow-up time, co-existing injury existence, repair time, single or multiple finger injury, tendon rupture and the effect of FDS injury and repair.

Results

Excellent, good, fair, poor results were obtained from 71 (55.5%), 46 (35.9%), 8 (6.3%), 3 (2.3%) fingers, respectively. Time of the repair has a significant effect on the strickland scores. Surgery performed within the first 24 hours following the injury gave better results. 3 fingers (2.3%) had tendon ruptures. Existence of ruptures affected the results significantly. Co-existing injuries were found that they did not have any effect on the results. In the fingers in which both FDP and FDS tendons were lacerated, no significant relationship was found between only FDP repair, both FDP and FDS repair and single FDS slip repair. Additionally no significant relationships between follow-up time, gender, single or multiple finger injury and Strickland scores were observed. 13 fingers (10.1%) had PIP joint contracture above 20°.

Conclusion

The low rupture rate (2.3%) and 91.4% ‘good’ and ‘excellent’ scoring rates in our series support the idea that modified Kessler 4-strand core suture and epitendinous interlocking suture repair combined with modified Kleinert protocol gives satisfactory results. Repair time is one of the most important factors affecting the functional results and surgery should not be delayed if there is an experienced surgeon available.

Level of evidence

Level IV, therapeutic study.

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.

[Suture techniques and material in surgery of flexor tendons]

Adhesions and scar formation between flexor tendons and the surrounding tissue are only contemporarily avoidable by movement of flexor tendons. Concepts with active follow-up protocols are more favorable than passive mobilization. The main risks of flexor tendon repair are rupture of the tendon suture, insidious gap formation and resistance to tendon gliding within the tendon sheath. Currently, there is no consensus with respect to the optimal suture technique or suture material. Nevertheless, there are some principles worth paying attention to, such as using stronger suture material, blocking stitches, suture techniques with four or more strands as well as circular running sutures. A technically acceptable compromise, even for the less experienced, is currently the four-strand suture combined with a circular running suture. It maintains sufficient stability for active motion follow-up protocols without resistance.

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.

Effect of Suture Caliber and Number of Core Strands on Repair of Acute Achilles Ruptures: A Biomechanical Study

BACKGROUND

Controversy exists regarding the ideal Achilles rupture treatment; however, operative treatment is considered for athletes and active patients. The ideal repair construct is evolving, and the effect of suture caliber or number of core strands has not been studied.

METHODS

Simulated mid-substance Achilles ruptures were performed in 24 cadavers. Specimens were randomized to three 6-core-strand style repair constructs: (1) 4 No. 2 sutures and two 2-mm tapes (2T); (2) 2 No. 2 sutures and four 2-mm tapes (4T); (3) 12 (double-6-strand) strand repair (12 No. 2-0 sutures [12S]). Repairs were subjected to a cyclic loading protocol representative of postoperative rehabilitation. These data were compared to a previously published standard open repair technique (6-core strands with No. 2 sutures) on 9 specimens tested under the same conditions.⁶ Results: No significant elongation differences were observed between the repair groups and the previously published standard repair group in the first 2 stages of the simulated rehabilitation protocol. Both the 2T and 12S repairs survived a significantly greater number of cycles to failure ( P = 0.0005, P = 0.0267, respectively) and had a significantly higher failure load ( P = .0005, P = .0118, respectively) compared to the previously published data. These 2 constructs consistently survived the advanced stages of the simulated rehabilitation protocol. The majority of repairs failed at the knots.

CONCLUSIONS

In this study, the 2T and 12S constructs survived the later stages of our simulated rehabilitation protocol, suggesting that they may be able to accommodate a more aggressive clinical rehabilitation protocol. Substituting suture-tape for 2 core strands or doubling the core strands with a smaller-caliber suture created a biomechanically stronger construct.

CLINICAL RELEVANCE

Achilles repair with an added nonabsorbable, high-tensile strength tape allowed for a stronger construct that may allow for a more aggressive, early rehabilitation protocol and earlier return to function.

Zone II Flexor Tendon Repairs in the United States: Trends in Current Management

PURPOSE

The repair of zone II flexor tendon injuries is an evolving topic in hand surgery with current literature suggesting the use of a 4-strand repair; 3-0 or 4-0 braided, nonabsorbable sutures; and an epitendinous repair. It was hypothesized that variability would exist within the hand surgeon community in treatment of zone II flexor tendon repairs in surgical material used, surgical technique, and postoperative rehabilitation protocol.

METHODS

An online single-answer multiple-choice survey was distributed to the American Society for Surgery of the Hand members' database. Surgeons were asked questions about demographics, surgical technique, suture type, common complications, postoperative management, and the factor that plays the largest role in guiding their surgical preferences. Responses were compared with current medical evidence.

RESULTS

A total of 410 individuals responded to the survey. In regards to technique, the majority of surgeons reported using a 4-strand repair; with 3-0 or 4-0 core braided, nonabsorbable sutures; and performing an epitendinous repair. Only 20% of surgeons surveyed reported ever using wide-awake local anesthesia, no tourniquet and postoperative protocols were split between early active and early passive rehabilitation. Senior surgeons (≥ 15 years in practice) were more likely than their colleagues to use a 2-strand repair and a passive rehabilitation protocol.

CONCLUSIONS

This study demonstrates that the majority of respondents are performing zone II flexor tendon repairs in accordance with the best currently available evidence, although there is variability with respect to suture material, surgical technique, and rehabilitation protocols.

CLINICAL RELEVANCE

There is still a need for high-quality studies on surgical technique and rehabilitation protocols.

Eight-strand Cross-locked Cruciate Flexor Tendon Repair Using Double-stranded Suture: A Description of the Surgical Technique

This article describes a technique for improved repair of digital flexor tendon laceration. Eight-strand cross-locked cruciate repair using 4-0 caliber double-stranded suture is not bulky and has a smooth configuration for tendon gliding. Additionally, it has sufficient strength for early postoperative active motion exercise.

Surgical Sutures with Porous Sheaths for the Sustained Release of Growth Factors

Surgical sutures with highly porous sheaths are developed using a swelling and freeze-drying procedure without compromising their mechanical properties. The modified sutures show a high capacity for loading biofactors and are able to release the loaded biofactors in a sustained manner.

Enhanced Zone II Flexor Tendon Repair through a New Half Hitch Loop Suture Configuration

This study evaluated the impact of a new half hitch loop suture configuration on flexor tendon repair mechanics. Cadaver canine flexor digitorum profundus tendons were repaired with 4- or 8-strands, 4-0 or 3-0 suture, with and without half hitch loops. An additional group underwent repair with half hitch loops but without the terminal knot. Half hitch loops improved the strength of 8-strand repairs by 21% when 4-0, and 33% when 3-0 suture was used, and caused a shift in failure mode from suture pullout to suture breakage. 8-strand repairs with half hitch loops but without a terminal knot produced equivalent mechanical properties to those without half hitch loops but with a terminal knot. 4-strand repairs were limited by the strength of the suture in all groups and, as a result, the presence of half hitch loops did not alter the mechanical properties. Overall, half hitch loops improved repair mechanics, allowing failure strength to reach the full capability of suture strength. Improving the mechanical properties of flexor tendon repair with half hitch loops has the potential to reduce the postoperative risk of gap formation and catastrophic rupture in the early postoperative period.

Flexor Tendon Repair: Healing, Biomechanics, and Suture Configurations

Successful outcome after flexor tendon repair requires a delicate balance between tendon healing and limiting scar tissue formation. Recent studies have highlighted the importance of the number of core sutures crossing the repair and the benefits of specific suture configurations in determining the strength of tendon repair. Researchers have attempted to augment the biological environment to improve the speed and strength of tendon repair.

Shear lag sutures: Improved suture repair through the use of adhesives

Suture materials and surgical knot tying techniques have improved dramatically since their first use over five millennia ago. However, the approach remains limited by the ability of the suture to transfer load to tissue at suture anchor points. Here, we predict that adhesive-coated sutures can improve mechanical load transfer beyond the range of performance of existing suture methods, thereby strengthening repairs and decreasing the risk of failure. The mechanical properties of suitable adhesives were identified using a shear lag model. Examination of the design space for an optimal adhesive demonstrated requirements for strong adhesion and low stiffness to maximize the strength of the adhesive-coated suture repair construct. To experimentally assess the model, we evaluated single strands of sutures coated with highly flexible cyanoacrylates (Loctite 4903 and 4902), cyanoacrylate (Loctite QuickTite Instant Adhesive Gel), rubber cement, rubber/gasket adhesive (1300 Scotch-Weld Neoprene High Performance Rubber & Gasket Adhesive), an albumin-glutaraldehyde adhesive (BioGlue), or poly(dopamine). As a clinically relevant proof-of-concept, cyanoacrylate-coated sutures were then used to perform a clinically relevant flexor digitorum tendon repair in cadaver tissue. The repair performed with adhesive-coated suture had significantly higher strength compared to the standard repair without adhesive. Notably, cyanoacrylate provides strong adhesion with high stiffness and brittle behavior, and is therefore not an ideal adhesive for enhancing suture repair. Nevertheless, the improvement in repair properties in a clinically relevant setting, even using a non-ideal adhesive, demonstrates the potential for the proposed approach to improve outcomes for treatments requiring suture fixation. Further study is necessary to develop a strongly adherent, compliant adhesive within the optimal design space described by the model.

In vivo flexor tendon forces generated during different rehabilitation exercises

We measured in vivo forces in the flexor digitorum profundus and the flexor digitorum superficialis tendons during commonly used rehabilitation manoeuvres after flexor tendon repair by placing a buckle force transducer on the tendons of the index finger in the carpal canal during open carpal tunnel release of 12 patients. We compared peak forces for each manoeuvre with the reported strength of a flexor tendon repair. Median flexor digitorum profundus force (24 N) during isolated flexor digitorum profundus flexion and median flexor digitorum superficialis force (13 N) during isolated flexor digitorum superficialis flexion were significantly higher than during the other manoeuvres. Significantly higher median forces were observed in the flexor digitorum superficialis with the wrist at 30° flexion (6 N) compared with the neutral wrist position (5 N). Median flexor digitorum profundus forces were significantly higher during active finger flexion (6 N) compared with place and hold (3 N). Place and hold and active finger flexion with the wrist in the neutral position or tenodesis generated the lowest forces; isolated flexion of these tendons generated higher forces along the flexor tendons.

LEVEL OF EVIDENCE

III (controlled trial without randomization).

The Effect of the Epitendinous Suture on Gliding in a Cadaveric Model of Zone II Flexor Tendon Repair

PURPOSE

We hypothesized that increasing core sutures (4-6) may be preferable in terms of gliding coefficient (GC) measurements when compared with adding an epitendinous suture to zone II flexor tendon repairs. We hypothesized that the inclusion of epitendinous suture in 2 standard repairs would contribute negatively to the GC of the repaired tendon.

METHODS

Nineteen fresh-frozen cadaveric fingers were used for testing. We compared a control group (dissected digits without repair) and 4-strand or 6-strand core tendon repairs with and without epitendinous suture. Arc of motion was driven by direct loading, and digital images were acquired and analyzed. Outcomes were defined as the difference in GC between the native uninjured and the repaired state at each load. A linear mixed-model analysis was performed with comparisons between repairs to evaluate the statistically relevant differences between groups.

RESULTS

The test of fixed effects in the linear model revealed that repair type and the use of epitendinous suture significantly affected the change in GC. The addition of an epitendinous suture produced a significant decrement in gliding regardless of repair type.

CONCLUSIONS

There was significant improvement in GC with the omission of the epitendinous suture in both repair types (4- or 6-strand).

CLINICAL RELEVANCE

The epitendinous suture used in this model resulted in poorer gliding of the repair, which may correspond with an expected increase in catching or triggering.

Development of antisense oligonucleotide (ASO) technology against Tgf-β signaling to prevent scarring during flexor tendon repair

Flexor tendons (FT) in the hand provide near frictionless gliding to facilitate hand function. Upon injury and surgical repair, satisfactory healing is hampered by fibrous adhesions between the tendon and synovial sheath. In the present study we used antisense oligonucleotides (ASOs), specifically targeted to components of Tgf-β signaling, including Tgf-β1, Smad3 and Ctgf, to test the hypothesis that local delivery of ASOs and suppression of Tgf-β1 signaling would enhance murine FT healing by suppressing adhesion formation while maintaining strength. ASOs were injected in to the FT repair site at 2, 6 and 12 days post-surgery. ASO treatment suppressed target gene expression through 21 days. Treatment with Tgf-β1, Smad3 or Ctgf ASOs resulted in significant improvement in tendon gliding function at 14 and 21 days, relative to control. Consistent with a decrease in adhesions, Col3a1 expression was significantly decreased in Tgf-β1, Smad3 and Ctgf ASO treated tendons relative to control. Smad3 ASO treatment enhanced the maximum load at failure of healing tendons at 14 days, relative to control. Taken together, these data support the use of ASO treatment to improve FT repair, and suggest that modulation of the Tgf-β1 signaling pathway can reduce adhesions while maintaining the strength of the 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.

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.