Comparative biomechanical performances of 4-strand core suture repairs for zone II flexor tendon lacerations

2-Octyl cyanoacrylate adjuvant use in calcaneal tendon repair: A comparative experimental study in rabbits

Purpose

The treatment of Achilles tendon (AT) rupture can be conservative or surgical; the latter is better indicated in high-performance athletes. The pursuit of faster recovery and reductions in skin complications and re-ruptures have improved the tendon repair technique and early assisted rehabilitation programs. Our goal was to check whether or not the adjuvant use of 2-octyl cyanoacrylate (CA) provides additional mechanical resistance to the calcaneal tenorrhaphy when compared to sutures alone.

Methods

In the study, 45 rabbits were used, and distributed into three groups of 15 animals each. They underwent two surgical procedures at a 30-day interval. In the first, a complete AT section was done on the right side and then was repaired using three different techniques: suture alone in Group 1, suture with 2-octyl CA in Group 2 and 2-octyl CA alone in Group 3. After 30 days, the rabbits were euthanized, and their right-side calcaneal tendon was resected, and sent the specimen for pathology analysis. Then, a cross-section of the left calcaneal tendon was performed, and the same three repair techniques were used. After 15 min, the repaired tendons to the linear traction mechanical strength test were done.

Results

The results from the linear strength test showed that suture with glue outperformed suture alone (p = 0.0427), and glue alone (p < 0.0001). The pathology results were evaluated according to inflammation, repair process and tendon thickness. The report mentioned a high-intensity mixed inflammatory pattern (acute and chronic), outstanding neovascularization, tissue necrosis and abscess in most of the cases that used CA. However, there were no local or systemic clinical signs of an infectious process.

Conclusions

2-octyl CA added immediate mechanical strength to the calcaneal tendon repair in the rabbits, without increasing local complications, despite pathological changes up to 30 days after the repair.

Level of Evidence

NA study.

Current clinical opinion on surgical approaches and rehabilitation of hand flexor tendon injury-a questionnaire study

The management of flexor tendon injury has seen many iterations over the years, but more substantial innovations in practice have been sadly lacking. The aim of this study was to investigate the current practice of flexor tendon injury management, and variation in practice from the previous reports, most troublesome complications, and whether there was a clinical interest in potential innovative tendon repair technologies. An online survey was distributed via the British Society for Surgery of the Hand (BSSH) and a total of 132 responses were collected anonymously. Results showed that although most surgeons followed the current medical recommendation based on the literature, a significant number of surgeons still employed more conventional treatments in clinic, such as general anesthesia, ineffective tendon retrieval techniques, and passive rehabilitation. Complications including adhesion formation and re-rupture remained persistent. The interest in new approaches such as use of minimally invasive instruments, biodegradable materials and additive manufactured devices was not strong, however the surgeons were potentially open to more effective and economic solutions.

Knotless Tendon Repair with a Resorbable Barbed Suture: An In-vivo Comparison in the Turkey Foot

Background: Un-knotted barbed suture constructs are postulated to decrease repair bulk and improve tension loading along the entire repair site resulting in beneficial biomechanical repair properties. Applying this repair technique to tendons has shown good results in ex-vivo experiments previously but thus far no in-vivo study could confirm these. Therefore, this current study was conducted to assess the value of un-knotted barbed suture repairs in the primary repair of flexor tendons in an in-vivo setting. Methods: Two groups of 10 turkeys (Meleagris gallapovos) were used. All turkeys underwent surgical zone II flexor tendon laceration repairs. In group one, tendons were repaired using a traditional four-strand cross-locked cruciate (Adelaide) repair, while in group two, a four-strand knotless barbed suture 3D repair was used. Postoperatively repaired digits were casted in functional position, and animals were left free to mobilise and full weight bear, resembling a high-tension post-op rehabilitation protocol. Surgeries and rehabilitations went uneventful and no major complications were noted. The turkeys were monitored for 6 weeks before the repairs were re-examined and assessed against several outcomes, such as failure rate, repair bulk, range of motion, adhesion formation and biomechanical stability. Results: In this high-tension in-vivo tendon repair experiment, traditionally repaired tendons performed significantly better when comparing absolute failure rates and repair stability after 6 weeks. Nevertheless, the knotless barbed suture repairs that remained intact demonstrated benefits in all other outcome measures, including repair bulk, range of motion, adhesion formation and operating time. Conclusions: Previously demonstrated ex-vivo benefits of flexor tendon repairs with resorbable barbed sutures may not be applicable in an in-vivo setting due to significant difference in repair stability and failure rates. Level of Evidence: Level IV (Therapeutic).

A 3-Dimensional Suture Technique for Flexor Tendon Repair: A Biomechanical Study

PURPOSE

Flexor tendon injury continues to pose a number of challenges for hand surgeons. Improving mechanical properties of repairs should allow for earlier and unprotected rehabilitation. A 3-dimensional (3D) 4-strand suture technique has been proposed to combine high tensile strength and low gliding resistance without causing suture pullout due to tendon delamination. Our hypothesis is that the 3D technique can result in better mechanical properties than the Adelaide technique.

METHODS

Four groups of 10 porcine flexor tendons were sutured using the 3D or Adelaide technique with a 3-0 polypropylene or ultrahigh molecular weight polyethylene (UHMWPE) suture. The axial traction test to failure was performed on each tendon to measure 2-mm gap force and ultimate tensile strength.

RESULTS

The mean 2-mm gap force was 49 N for group A (3D + polypropylene), 145 N for group B (3D + UHMWPE), 47 N for group C (Adelaide + polypropylene), and 80 N for group D (Adelaide + UHMWPE). Failure mode was caused by suture breakage for group A (10/10) and mainly by suture pullout for the other groups (8/10 up to 10/10). With the UHMWPE suture, the mean ultimate tensile strength was 145 N for the 3D technique and 80 N for the Adelaide technique.

CONCLUSIONS

Porcine flexor tendons repaired using the 3D technique and UHMWPE suture exceeded a 2-mm gap force and tensile strength of 140 N. The ultimate tensile strength was superior to that of the Adelaide technique, regardless of the suture material.

CLINICAL RELEVANCE

This in vitro study on porcine flexor tendon suture highlights that the mechanical properties of 3D repair are better than those of 3D repair using the Adelaide technique when a UHMWPE suture is used.

Effect of Oblique Tendon Laceration on Core Suture Strength: A Biomechanical Evaluation

BACKGROUND

The effect of obliquity of tendon laceration on repair strength is not well studied. The overwhelming majority of biomechanical studies assess repair strength following a laceration that is perpendicular to the long axis of the tendon. The aim of this study was to investigate whether the angle of tendon laceration affects the core suture strength.

METHODS

In all, 110 fresh human cadaveric flexor tendons were cut at varying angles of 15°, 30°, 45°, and 60° and the control group at 90°. All tendons were repaired with 6-strand modified Tang technique. The repair strength was tested using a custom-made tensioning machine, and the initial static gap force and the ultimate breaking force were measured.

RESULTS

The mean gap force and 95% confidence interval (CI) for the 15°, 30°, 45°, 60°, and 90° groups were 15.2 N (11.4-19.0 N), 15.8 N (13.6-18.1 N), 15.6 N (13.1-18.4 N), 16.6 N (13.7-19.5 N), and 22.3 N (16.6-27.9 N), respectively. In the same respective order, the break force and 95% CI were 25.9 N (21.9-29.8 N), 26.5 N (23.2-29.7 N), 31.1 N (26.1-36.1 N), 35.6 N (28.2-43.1 N), and 51.8 N (62.5-41.0), respectively. The Fisher least significant difference demonstrated significant differences between the control group and all experimental groups for both gap force and break force.

CONCLUSIONS

Obliquity of tendon laceration affects the core suture strength when compared with a transverse cut. Flexor tendons cut at 90° demonstrated a higher overall gap force and breaking strength that were statistically significant when compared with all obliquely cut groups. These findings should be considered when repairing and starting postoperative therapy for obliquely cut tendons.

Biomechanical Study of Modified Massachusetts General Hospital Flexor Tendon Repair Using Looped Sutures

Background: Massachusetts General Hospital (MGH) repair is one of the widely used 4-strand flexor tendon repair techniques. However, it uses two single strand sutures that are each passed twice across the repair site. This is time consuming and may cause imbalance of the load across the repair. We modified the MGH repair by using a looped suture and call it the looped MGH repair. The aim of this study is to compare the strength of the looped MGH repair performed with three different looped sutures against the strength of original MGH repair.

Methods: Forty porcine flexors were used for the study. The original MGH repair was performed with Prolene® 4-0. Looped MGH repair was performed with three different loop sutures, Supramid® 4-0, Tendo-Loop® 4-0 and FiberLoop® 4-0. Mechanism of failure, ultimate tensile strength, stiffness, load to 2-mm gap formation and repair time were recorded for comparison.

Results: There was no significant difference between the original MGH repair and the looped repair using Supramid® regarding their biomechanical performance. Looped MGH repair using Tendo-Loop® and FiberLoop® showed significantly higher ultimate tensile strength and FiberLoop® had highest 2-mm gap force. All looped MGH repairs required significant less time compared to original MGH repair.

Conclusions: Our modification of the MGH repair using a looped Supramid® 4-0 suture took significantly lesser time to perform while providing the same strength as the original MGH repair using Prolene® 4-0. The use of the FiberLoop® 4-0 provided significantly greater strength while taking lesser time.

Repair of flexor tendon injuries by four strands cruciate technique versus two strands kessler technique

BACKGROUND

Flexor tendon injuries are commonly encountered and the surgical repair still represents a challenging problem. Many repair techniques are present but there is still no ideal one that achieves the best functional outcome. This study was undertaken to compare four-strand locked cruciate repair technique and modified Kessler technique in forty eight patients by assessing the functional outcome.

METHODS

Forty eight patients (114 digits) with flexor tendon injury were assigned into two groups based on suture repair technique; Group A: 24 cases by Modified Kessler repair (50%). Group B: 24cases by 4-strand cruciate repair (50%). Adults in Both groups were rehabilitated by combined Duran protocol and early active mobilization while no specific rehabilitation program was used for pediatric age group. Follow up was from 6 to 36 months (mean 21.5). Functional outcome was assessed by White criteria to all patients after 6 months.

RESULTS

Functional outcome was better in 4 strand cruciate repair with excellent result in 66.6%, good in 29.1% and fair in 4.1%, as compared to modified Kessler technique in which excellent results were found in 45.8%, good in 37.5%, fair in 12.5% and poor in 4.1% of cases. A better functional result was achieved in 4 strand cruciate repair especially in zone II, with excellent results in 33.3%, good in 50% and fair in 16.6% of cases, as compared to modified Kessler repair with no excellent results, 33.3% good, 50% fair and 16.6% poor results. In zone III, 4 strand cruciate technique showed a better functional outcome with 77.7% excellent and 22.2% good results, as compared to 55.5% excellent and 44.4% good results found in Modified Kessler repair. Zone V showed almost comparable results between the two types of repairs.

CONCLUSION

The 4-strand cruciate repair technique had better functional outcome compared to modified Kessler repair technique, especially in zone II and III.

Flexor Subzone II A-D Range of Motion Progression during Healing on a No-Splint, No-Tenodesis Protection, Immediate Full Composite Extension Regimen

Background: The objective was to study the hypotheses that an advanced zone II flexor tendon rehabilitation protocol would avoid rupture, achieve a high range of excursion, and minimize interphalangeal contracture during both the early phases and at the conclusion of healing. We also proposed the null hypothesis of no difference between any two of the zone II subdivisions. Methods: Fifty-one consecutive adult patients with zone II flexor tendon repairs of a single finger were retrospectively evaluated on an active contraction rehabilitation protocol with no splint, no tenodesis protection, and immediate full composite extension. There were 38 males and 13 females with a mean age of 39 years (range 18-69) involving 15 index, 7 long, 6 ring, and 23 small fingers. Repairs were located in flexor subzone IIA for 8 fingers; subzone IIB, 14; subzone IIC, 19; and subzone IID, 10. Differences in outcome between any two subzones were compared by T-test with p < 0.05. Results: Mean active arcs of motion in degrees at 3 weeks post repair were PIP 1-93; DIP 0-44; and total active motion (TAM) 221. At 6 weeks PIP 2-98; DIP 1-51; and TAM 236. At 10-12 weeks PIP 1-101; DIP 1-56; and TAM 246. Final TAM by flexor subzone IIA was 243; IIB, 251; IIC, 246; and IID, 246. There were no significant differences between any two subzones. Mean final DASH score was 5. There were no ruptures. Conclusions: The results support the hypotheses. Outcomes of the therapy protocol demonstrated the lack of interphalangeal joint flexion contractures, high range of total active motion achieved early and sustained, and no ruptures. No differences were identified between and two of the flexor subzones.

Biomechanical Properties of a Novel Mesh Suture in a Cadaveric Flexor Tendon Repair Model

PURPOSE

Conventional suture repairs, when stressed, fail by suture rupture, knot slippage, or suture pull-through, when the suture cuts through the intervening tissue. The purpose of this study was to compare the biomechanical properties of flexor tendon repairs using a novel mesh suture with traditional suture repairs.

METHODS

Sixty human cadaveric flexor digitorum profundus tendons were harvested and assigned to 1 of 3 suture repair groups: 3-0 and 4-0 braided poly-blend suture or 1-mm diameter mesh suture. All tendons were repaired using a 4-strand core cruciate suture configuration. Each tendon repair underwent linear loading or cyclic loading until failure. Outcome measures included yield strength, ultimate strength, the number of cycles and load required to achieve 1-mm and 2-mm gap formation, and failure.

RESULTS

Mesh suture repairs had significantly higher yield and ultimate force values when compared with 3-0 and 4-0 braided poly-blend suture repairs under linear testing. The average force required to produce repair gaps was significantly higher in mesh suture repairs than in conventional suture. Mesh suture repairs endured a significantly greater number of cycles and force applied before failure compared with both 3-0 and 4-0 conventional suture.

CONCLUSIONS

This ex vivo biomechanical study of flexor tendon repairs using a novel mesh suture reveals significant increases in average yield strength, ultimate strength, and average force required for gap formation and repair failure with mesh suture repairs compared with conventional sutures.

CLINICAL RELEVANCE

Mesh suture-based flexor tendon repairs could lead to improved healing at earlier time points. The findings could allow for earlier mobilization, decreased adhesion formation, and lower rupture rates after flexor tendon repairs.

Biomechanical Comparison of a New Loop Suture Technique With Conventional Techniques of Flexor Tendon Repair: An In Vitro Study

INTRODUCTION

Flexor tendon repair techniques that can resist active forces are widely accepted. Despite that many suture techniques have been described, the "perfect repair" for flexor tendons cannot be achieved yet. We aimed to compare a new loop suture technique with commonly used flexor tendon repair methods biomechanically in hen tendon.

METHOD

We used 25 hen flexor tendons for each group (4-strand modified Kessler, grasping cruciate, Tsuge, and new technique groups). After the tendons were divided into 2, they were repaired according to these 4 techniques, were subjected to the initial stretching of 0.5 N, and pulled in the opposite directions. When a gap of 2 mm occurred, the test was terminated and the forces at that time were recorded. These strain forces were compared and evaluated statistically.

RESULTS

New technique had the best tensile strength results statistically. Modified Kessler and grasping cruciate took the second place and Tsuge repair gave the worst strain forces results.

CONCLUSIONS

With loop suture, 4 strands can be obtained with only 2 passes of the needle, and we think that much more tensile strength can be achieved because of the vertical transition and locking configurations of the new loop suture technique.

A Biomechanical Study of a Novel Asymmetric 6-Strand Flexor Tendon Repair Using Porcine Tendons

BACKGROUND

This study evaluated the biomechanical performance of a novel asymmetric 6-strand flexor tendon repair technique without locking loops.

METHODS

Twenty porcine flexor tendons were equally repaired by using the asymmetric technique and compared with the modified Lim-Tsai repair technique. The ultimate tensile strength, load to 1-mm gap force, stiffness, and mechanism of failure were measured.

RESULTS

The asymmetric repair technique had significantly higher tensile strength (63.3 ± 3.7 N) than the modified Lim-Tsai repairs (46.7 ± 8.3 N).

CONCLUSIONS

A novel flexor tendon repair technique with improved biomechanical performance may be available for use in flexor tendon repairs.

A Biomechanical Comparison of Different Knots Tied on Fibrewire Suture

BACKGROUND

Synthetic sutures such as Fiberwire used in flexor tendon repairs have high tensile strength. Proper application allows early mobilisation, decreasing morbidity from repair rupture and adhesions while preserving range of motion. Suture stiffness can cause poorer knot holding, contributing to gapping, peritendinous adhesions or rupture. Previous studies recommended more throws in knots tied on Fiberwire to prevent knot slippage. These larger knots are voluminous and prominent. In tendon repairs they can cause "catching", increase friction and work of flexion. Other studies advocated certain complicated knots as being more secure. We evaluated several knots and their biomechanical properties with the aim of finding a compact knot with less potential for slippage to maximise strength potential of flexor tendon repairs using Fiberwire.

METHODS

A series of different knots tied on Fiberwire 4-0 sutures were pulled to failure on a mechanical tester. Mean tensile strengths, knot volumes and tensile strength to knot volume ratios were compared.

RESULTS

Tensile strengths and knot volume increased with more throws and loops. Four variations of the square knot (the 4=4=1, 2=2=2=2, 1=1=1=1=1, 2=1=1=1=1 knots) had tensile strengths greater than 35N. The specialised anti-slip knot had highest tensile strength and suture volume but lower strength-to-volume ratio.

CONCLUSIONS

The anti-slip knot had highest tensile strength but it also had the highest volume. The greater strength of repair may not translate into improved clinical outcome. The 1=1=1=1=1 knot has superior knot strength-to-volume ratio with good knot strength adequate for early active mobilisation in flexor tendon repairs.

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.

Augmented and virtual reality in surgery-the digital surgical environment: applications, limitations and legal pitfalls

The continuing enhancement of the surgical environment in the digital age has led to a number of innovations being highlighted as potential disruptive technologies in the surgical workplace. Augmented reality (AR) and virtual reality (VR) are rapidly becoming increasingly available, accessible and importantly affordable, hence their application into healthcare to enhance the medical use of data is certain. Whether it relates to anatomy, intraoperative surgery, or post-operative rehabilitation, applications are already being investigated for their role in the surgeons armamentarium. Here we provide an introduction to the technology and the potential areas of development in the surgical arena.

Forces Transmitted Along Human Flexor Tendons During Passive and Active Movements of the Fingers

The in vivo forces in human digital flexor tendons were determined in 33 patients undergoing a carpal tunnel decompression surgery using a newly developed device. The tendons were tested in passive and active flexion, and flexing against resistance of up to 500 g. Forces in the range of 0.2 to 50 N were noted. Whilst the mean of these forces remained below the force normally required to dehisce a fresh modified Kessler repair, the range of values was such that we would only recommend early movement with great caution and under supervision.

Repairs of Partial Oblique Tendon Injuries: A Biomechanical Evaluation

This study evaluated the tensile properties of oblique partial tendon lacerations and the effects of peripheral sutures on their strength. Seventy-four fresh pig flexor digitorum profundus tendons were divided into eight groups and were transected across 90% of their diameter. The lacerations in the tendons of five of the groups were at 0°, 15°, 30°, 45°, and 60° to their transverse cross-section, respectively. In the other three groups the lacerations were 0°, 45°, and 60° to the cross-section and were repaired with running peripheral sutures. The tendons were subjected to load-to-failure tests in a tensile testing machine to determine the initial, 1 and 2 mm gap formation forces, and the ultimate strength. Obliquity of tendon lacerations affected the strength of partially lacerated tendons. The tendons with 45° and 60° oblique lacerations had a significantly lower ultimate strengths than those with transverse (0°), or 15° or 30° oblique lacerations. Running peripheral sutures significantly increased both the gap formation forces and the ultimate strength of the tendons with oblique partial lacerations.

Effect of wrist and interphalangeal thumb movement on zone T2 flexor pollicis longus tendon tension in a human cadaver model

INTRODUCTION

Therapy after flexor pollicis longus (FPL) repair typically mimics finger flexor management, but this ignores anatomic and biomechanical features unique to the FPL.

PURPOSE OF THE STUDY

We measured FPL tendon tension in zone T2 to identify biomechanically appropriate exercises for mobilizing the FPL.

METHODS

Eight human cadaver hands were studied to identify motions that generated enough force to achieve FPL movement without exceeding hypothetical suture strength.

RESULTS

With the carpometacarpal and metacarpophalangeal joints blocked, appropriate forces were produced for both passive interphalangeal (IP) motion with 30° wrist extension and simulated active IP flexion from 0° to 35° with the wrist in the neutral position.

DISCUSSION

This work provides a biomechanical basis for safely and effectively mobilizing the zone T2 FPL tendon.

CONCLUSION

Our cadaver study suggests that it is safe and effective to perform early passive and active exercise to an isolated IP joint.

LEVEL OF EVIDENCE

NA.

Flexor Tendon Repair With Looped Suture: 1 Versus 2 Knots

PURPOSE

To assess the strength of flexor tendon repair with looped suture. We hypothesized that, after passing the intact looped suture in the desired repair configuration, splitting the loop and tying 2 independent knots would increase the strength of flexor tendon repair.

METHODS

Thirty-two flexor tendons were harvested and were sharply transected in zone II. The tendons were repaired with a 4-strand core suture repair using 3-0 looped nonabsorbable nylon suture. The harvested tendons were randomly assigned and repaired with either a 1- or a 2-knot construct. The repaired flexor tendons were fixed in a servohydraulic material testing system and were loaded to failure either with uniaxial tension or cyclically.

RESULTS

The average force at failure was 43 N for the 1-knot repair and 28 N for the 2-knot repair. The mode of failure of 15 of the flexor tendon repairs that were cyclically loaded to failure was suture pull-out. The average number of cycles and force in cyclic testing that caused failure of flexor tendon repairs was 134 cycles and 31 N for tendons repaired with looped 3-0 suture tied with 1 knot and 94 cycles and 33 N for tendons repaired with looped 3-0 suture tied with 2 knots.

CONCLUSIONS

Our hypothesis was disproved by the results of this study.

CLINICAL RELEVANCE

This study suggests that, when using looped suture, tying 2 independent knots instead of tying a single knot does not increase the strength of the flexor tendon repair.

Biomechanical Study of the Digital Flexor Tendon Sliding Lengthening Technique

PURPOSE

To compare the mechanical properties of sliding lengthening (SL) and Z-lengthening (ZL) for flexor tendon elongation used for conditions such as Volkmann contracture, cerebral palsy, and poststroke spasticity.

METHODS

We harvested 56 flexor tendons, including flexor pollicis longus tendons, flexor digitorum superficialis tendons (zones II to IV), and flexor digitorum profundus tendons (zones II to V) from 24 upper limbs of 12 fresh cadavers. Each tendon was harvested together with its homonymous tendon from the opposite side of the cadaver and paired. We used 28 pairs of tendons and divided them randomly into 4 groups depending on the lengthening distance (20 or 30 mm) and type of stitching (single or double mattress sutures). Then we divided each pair into either the SL or ZL group. Each group was composed of 7 specimens. The same surgeon lengthened all tendons and stitched them with 2-0 polyester sutures. We tested biomechanical tensile strength immediately after completing lengthening and suturing in each group.

RESULTS

Ultimate tensile strengths were: 23 N for the SL 20-mm lengthening and single mattress suture and 7 N for the ZL; 25 N for the SL 20-mm lengthening and double mattress suture and 10 N for the ZL; 15 N for the SL 30-mm lengthening and single mattress suture and 8 N for the ZL; and 18 N for the SL 30-mm lengthening and double mattress suture and 10 N for the ZL.

CONCLUSIONS

The SL technique may be a good alternative to the ZL technique because it provides higher ultimate tensile strength.

CLINICAL RELEVANCE

Because of its higher ultimate tensile strength, the SL technique may allow for earlier rehabilitation and reduced risk of postoperative complications.

Biomechanical comparison of double grasping repair versus cross-locked cruciate flexor tendon repair

PURPOSE

This study was conducted to compare the in vitro biomechanical properties of tensile strength and gap resistance of a double grasping loop (DGL) flexor tendon repair with the established four-strand cross-locked cruciate (CLC) flexor tendon repair, both with an interlocking horizontal mattress (IHM) epitendinous suture. The hypothesis is that the DGL-IHM method which utilizes two looped core sutures, grasping and locking loops, and a single intralesional knot will have greater strength and increased gap resistance than the CLC-IHM method.

METHODS

Forty porcine tendons were evenly assigned to either the DGL-IHM or CLC-IHM group. The tendon repair strength, 2-mm gap force and load to failure, was measured under a constant rate of distraction. The stiffness of tendon repair was calculated and the method of repair failure was analyzed.

RESULTS

The CLC-IHM group exhibited a statistically significant greater resistance to gapping, a statistically significant higher load to 2-mm gapping (62.0 N), and load to failure (99.7 N) than the DGL-IHM group (37.1 N and 75.1 N, respectively). Ninety percent of CLC-IHM failures were a result of knot failure whereas 30 % of the DGL-IHM group exhibited knot failure.

CONCLUSIONS

This study demonstrates that the CLC-IHM flexor tendon repair method better resists gapping and has a greater tensile strength compared to the experimental DGL-IHM method. The authors believe that while the DGL-IHM provides double the number of sutures at the repair site per needle pass, this configuration does not adequately secure the loop suture to the tendon, resulting in a high percentage of suture pullout and inability to tolerate loads as high as those of the CLC-IHM group.

Biomechanical evaluation of 4-strand flexor tendon repair techniques, including a combined Kessler-Tsuge approach

PURPOSE

To test the ultimate tensile strength and stiffness of 3 flexor tendon repair techniques using looped suture material.

METHODS

Seventeen fresh porcine flexor tendons were randomized to a single-throw, 4-strand Kessler technique with a looped structure, a double-throw, 4-strand Tsuge technique with 2 looped structures, or a single-throw, 4-strand Kessler-Tsuge technique with a looped structure. Thirty additional fresh porcine flexor tendons were randomized to the same techniques but with a running epitendinous repair. We measured ultimate tensile strength to failure and stiffness and recorded the cause of failure.

RESULTS

The Tsuge technique had the highest mean ultimate tensile strength at 75 N (SD, 14 N) versus 63 N (SD, 13 N) for the Kessler-Tsuge method and 46 N (SD, 11 N) for the Kessler technique. Differences between the Tsuge and Kessler-Tsuge, the Kessler-Tsuge and Kessler, and the Tsuge and Kessler techniques were significant. Mean suture stiffness was 6.8 N/mm for the Tsuge technique, 5.7 N/mm for the Kessler-Tsuge technique, and 4.6 N/mm for the Kessler technique. The difference between the Tsuge and Kessler techniques was significant. Analyzing the tests with or without an epitendinous suture separately did not affect the significance of the differences.

CONCLUSIONS

The modified double-throw, 4-strand Tsuge was the strongest suture technique in this study. It may be a clinically acceptable, albeit slightly weaker alternative to the more complicated Tsuge method.

CLINICAL RELEVANCE

A combined Kessler-Tsuge approach might be an option for flexor tendon repair.

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.

The Interlocking Modification of the Cross Locked Cruciate Tendon Repair (Modified Adelaide Repair): A Static and Dynamic Biomechanical Assessment

The 4-strand cross-locked cruciate flexor tendon repair technique (Adelaide technique) has been shown to have comparably high resistance to gap formation and ultimate tensile strength. This study aimed to determine whether an interlocking modification to the Adelaide repair would impart improved biomechanical characteristics. Twenty four sheep flexor tendons were harvested, transected and repaired using either standard or modified Adelaide techniques. Repaired tendons were cyclically loaded. Gap formation and ultimate tensile strength were measured. Additionally, suture exposure on the tendon surface was determined. There was a statistically significant increase in resistance to gap formation in the early phase of cyclic loading within the modified Adelaide group. In the later stages of testing no significant difference could be noted. The average final load to failure in the modified group was higher than the standard group but this did not achieve statistical significance. Interlocking suture techniques in four strand tendon repair constructs can improve gapping behavior in the early phase of cyclic loading.

Flexor Tendon Injuries in the Hand: A UK Survey of Repair Techniques and Suture Materials—Are We Following the Evidence?

Introduction. Injuries to the hand are common, and poor functional outcomes can have significant long-term consequences affecting both work and social activities. Good outcomes following flexor tendon lacerations in the hand are dependent on a sound surgical repair allowing early active mobilisation. Materials and Methods. We reviewed the literature regarding the choice of suture material and repair technique. We then carried out a nationwide postal survey of plastic surgery hand units to assess the level of compliance with the evidence. Results. Fifty-four units were surveyed. The response rate was 72%, with the most popular core suture being Prolene (64%) and the most popular technique being the Kessler repair (36%). Discussion. Current evidence advocates a multistrand repair using Ethibond. We found that the majority of units are not following the evidence. We suggest the use of evidence-based departmental guidelines to improve the practice and outcomes following these common injuries.

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.

Biomechanical comparison of the four-strand cruciate and Strickland techniques in animal tendons

OBJECTIVE

The objective of this study was to compare two four-strand techniques: the traditional Strickland and cruciate techniques.

METHODS

Thirty-eight Achilles tendons were removed from 19 rabbits and were assigned to two groups based on suture technique (Group 1, Strickland suture; Group 2, cruciate repair). The sutured tendons were subjected to constant progressive distraction using a universal testing machine (Kratos®). Based on data from the instrument, which were synchronized with the visualized gap at the suture site and at the time of suture rupture, the following data were obtained: maximum load to rupture, maximum deformation or gap, time elapsed until failure, and stiffness.

RESULTS

In the statistical analysis, the data were parametric and unpaired, and by Kolmogorov-Smirnov test, the sample distribution was normal. By Student's t-test, there was no significant difference in any of the data: the cruciate repair sutures had slightly better mean stiffness, and the Strickland sutures had longer time-elapsed suture ruptures and higher average maximum deformation.

CONCLUSIONS

The cruciate and Strickland techniques for flexor tendon sutures have similar mechanical characteristics in vitro.

Clinical outcomes of zone II flexor tendon repair depending on mechanism of injury

PURPOSE

To determine whether mechanism of injury affects outcomes of Zone II flexor tendon repairs.

METHODS

We retrospectively analyzed patients who underwent Zone II flexor tendon repair between 2001 and 2010 with a minimum of 12-month follow-up. Exclusion criteria included fingers with fracture, pulley reconstruction, or flexor tendon bowstringing. The saw group injuries were from saws or from tearing mechanisms; the sharp group had clean transection injuries from knives or glass. At final evaluation, primary outcomes were total passive motion (TPM) and total active motion (TAM) at the proximal interphalangeal and distal interphalangeal joints. Secondary comparisons included strength, Disabilities of the Shoulder, Arm, and Hand (DASH) score, percentage of postoperative tendon rupture, and percentage of patients requiring secondary surgery. The saw group had 13 patients with 17 fingers studied. The sharp group had 21 patients with 24 fingers studied. All patients had primary flexor digitorum profundus repairs in Zone II. Operative records review confirmed for all but 1 patient that flexor digitorum profundus injuries were repaired with a minimum of a 4-strand core suture technique. In the saw group, 9 of 14 fingers with a 50% or greater laceration of flexor digitorum superficialis were repaired; in the sharp group, 15 of 18 such flexor digitorum superficialis injuries were repaired. Average follow-up was 4 years (range, 1-9 y).

RESULTS

The saw group had significantly less TAM and TPM compared with the sharp group. There was no significant difference in DASH scores, strength measurements, or tendon rupture rates. The rate of secondary surgery was significantly higher in the saw group.

CONCLUSIONS

Tearing types of injury, such as those caused by saws, led to poorer outcomes for Zone II flexor tendon injuries compared with sharp injuries at an average follow-up of 4 years. Our results can be useful when discussing expected outcomes. Mechanism of injury in Zone II flexor tendon lacerations may eventually help define optimal treatment.

Number of suture throws and its impact on the biomechanical properties of the four-strand cruciate locked flexor tendon repair with FiberWire

FiberWire is a popular suture in flexor tendon repair that allows for early mobilization, but its poor knot-holding properties have raised concerns over the potential effects on tendon healing and strength. We examined how the number of knot throws affects the 2 mm gap force, ultimate tensile strength, and mode of failure in a four-strand cruciate locked tendon repair in porcine flexor tendons in order to elucidate the optimal number of suture throws. There was no effect on the 2 mm gap force with increasing knot throws, but there was a significant increase in ultimate tensile strength. A minimum of six-knot throws prevents unravelling, whereas five out of 10 of repairs unravelled with less than six throws.

A biomechanical comparison of 3 loop suture materials in a 6-strand flexor tendon repair technique

PURPOSE

The braided polyblend (FiberWire) suture is recognized for its superiority in tensile strength in flexor tendon repair. The purpose of this study was to compare the biomechanical performance of 3 loop-suture materials used in a locking 6-strand flexor tendon repair configuration: braided polyblend (FiberLoop 4-0), cable nylon (Supramid Extra II 4-0), and braided polyester (Tendo-Loop 4-0). We hypothesized that, using this technique, the braided polyblend suture would give superior tensile strength compared with the other 2 suture materials.

METHODS

We divided 30 fresh porcine flexor tendons transversely and repaired each with 1 of the 3 suture materials using a modified Lim-Tsai 6-strand suture technique. We loaded the repaired tendons to failure using a materials testing machine and collected data on the mechanism of failure, ultimate tensile strength, gap strength, and stiffness.

RESULTS

Failure mechanisms for the repaired specimens were as follows: the braided polyblend had 50% suture breakage and 50% suture pullout; the cable nylon had 100% suture breakage; and the braided polyester had 80% suture breakage and 20% suture pullout. Specimens repaired with the braided polyblend suture had the highest mean ultimate tensile strength (97 N; standard deviation, 22) and the highest mean gap force (35 N; standard deviation, 7).

CONCLUSIONS

This study supports the findings of previous studies showing superior strength of the braided polyblend suture.

CLINICAL RELEVANCE

We were able to achieve up to 124 N in ultimate tensile strength and 48 N of gap force with this suture in porcine tendons. This gives greater confidence in starting immediate controlled passive or active rehabilitation after repair of flexor tendon injuries.

Simplifying four-strand flexor tendon repair using double-stranded suture: a comparative ex vivo study on tensile strength and bulking

We have compared a simple four-strand flexor tendon repair, the single cross-stitch locked repair using a double-stranded suture (dsSCL) against two other four-strand repairs: the Pennington modified Kessler with double-stranded suture (dsPMK); and the cruciate cross-stitch locked repair with single-stranded suture (Modified Sandow). Thirty fresh frozen cadaveric flexor digitorum profundus tendons were transected and repaired with one of the core repair techniques using identical suture material and reinforced with identical peripheral sutures. Bulking at the repair site and tendon-suture junctions was measured. The tendons were subjected to linear load-to-failure testing. Results showed no significant difference in ultimate tensile strength between the Modified Sandow (36.8 N) and dsSCL (32.6 N) whereas the dsPMK was significantly weaker (26.8 N). There were no significant differences in 2 mm gap force, stiffness or bulk between the three repairs. We concluded that the simpler dsSCL repair is comparable to the modified Sandow repair in tensile strength, stiffness and bulking.

The effect of the number of cross-stitches on the biomechanical properties of the modified becker extensor tendon repair

PURPOSE

The optimum number of cross-stitches in modified Becker repair for extensor tendon injury is not known. The purpose of this study was to compare the biomechanical characteristics of 1, 2, and 3 cross-stitches in modified Becker extensor repairs.

METHODS

We used 8 fresh-frozen cadaveric hands (24 fingers). We exposed extensor tendons of the index, middle, and ring fingers over the proximal phalanx, cut them transversely at the mid-portion of zone IV (proximal phalanx), and repaired them in situ with a modified Becker technique with 1, 2, or 3 cross-stitches using 4-0 braided suture. We randomized the tendons within each hand for the number of cross-stitches. Stiffness, yield load, ultimate load, energy absorbed, and gap formation were measured. After a 5 N preload, each repair was cyclically loaded from 5 to 25 N for 30 cycles and from 5 to 35 N for 30 cycles at a rate of 20 mm/min to simulate loads during postoperative rehabilitation. After cyclic loading, the specimens were loaded to failure.

RESULTS

The repair with 1 cross-stitch showed superior gap resistance and stiffness during cyclic loading compared with 2 and 3 cross-stitches. One cross-stitch also resulted in higher stiffness and yield strength in load to failure testing. However, 3 cross-stitch configurations displayed higher ultimate strength. All repairs failed by knot slippage.

CONCLUSIONS

A modified Becker extensor tendon repair with 1 cross-stitch provides superior mechanical properties for loads seen with postoperative rehabilitation compared with 2 and 3 cross-stitches for similar loads.

CLINICAL RELEVANCE

These findings may lead to reduced operative time and decreased tendon damage with superior results.

CLINICAL RESULTS OF EARLY ACTIVE MOBILISATION AFTER FLEXOR TENDON REPAIR

Between 2005 and 2006, ten patients with flexor digitorum profundus zone II injuries were included. The mean age was 41 (19–84) years. One thumb, two index, four middle, one ring and two little fingers were injured. Repair method comprised four-strand core suture and 6-0 circumferential sutures. Post-operative rehabilitation included immediate active extension, progressive passive full flexion and active hold in dorsal block splint. Follow-up was four (three to seven) months. Grip strength, pinch strength, ROM was 90% (70%–90%), 90% (60%–110%) and 90% (80%–100%) of normal digit, respectively. Mayo wrist scores were five excellent, two good and three fair. All patients were satisfied. Compared with another group of ten patients with the same suture method and Kleinert splintage, grip strength, pinch strength and ROM were 50%, 40% and 40% of normal side, respectively. All differences between these two groups were statistically significant (p < 0.01) by paired samples T-test. There was no re-rupture.

Modified Brunelli pull-out technique in flexor tendon repair for zone II: a study on 58 cases

BACKGROUND

The reconstruction of the continuity of flexor tendons disruptions in zone II still remains one of the most challenging problems in hand surgery. The ideal repair has to provide sufficient strength and the possibility of early mobilization in the attempt to obtain a functional range of motion. One of the methods which appears to respond to these requests is the pull-out technique described by Brunelli, which moves the tension from the level of the tendon disruption to the finger pulp over the tendon insertion.

METHODS

After using this method, but by doing some modifications of the original technique, our aim was to conduct a retrospective study looking at gap formation, suture strength, rupture rate, efficiency of the two-strand suture repair and of the early active mobilization against resistance in obtaining a good range of flexion rate. We reviewed a series of 71 flexor digitorum profundus disruptions in zone II, in 58 patients admitted in our service between 2000 and 2008, and treated with this method.

RESULTS

We achieved a complete range of flexion in 41 fingers (57.7%) and a flexion deficit of 5-10° in eight fingers (11.3%) and of 10-20° in 22 fingers (31%). We had no ruptures, major strength deficit, or bowstringing.

CONCLUSIONS

Our study demonstrates that, by moving the tension from the level of disruption to the finger pulp, the rehabilitation program can begin very early post surgery. We had 0% ruptures.

Influence of locking stitch size in a four-strand cross-locked cruciate flexor tendon repair

PURPOSE

The 4-strand cross-locked cruciate technique (Adelaide technique) for repairing flexor tendons in zone II is a favorable method in terms of strength and simplicity. The purpose of this study was to investigate the effects of varying the cross-lock stitch size in this repair technique. Outcomes measured were load to failure and gap formation.

METHODS

We harvested 22 deep flexor tendons from adult pig forelimbs and randomly allocated them into 2 groups. After cutting the tendons at a standard point, we performed a 4-strand cross-locked cruciate repair using 3-0 braided polyester with either 2-mm cross-locks (n = 11) or 4-mm cross-locks (n = 11). All repairs were completed with a simple running peripheral suture using 6-0 polypropylene. Repaired tendons were loaded to failure and the mechanism of failure, load to failure, stiffness, and load to 2-mm gap formation were determined.

RESULTS

All repairs failed by suture breakage; we noted no suture pullout. There was no difference in load to failure (71.7-71.1 N; p = .89) or stiffness (4.1-4.6 N/mm; p = .23) between the 2-mm cross-lock and the 4-mm cross-lock groups. There was a trend toward higher resistance to 2-mm gap formation with the 4-mm cross-locks (55-62.2 N; p = .07).

CONCLUSIONS

Four-strand cross-locked cruciate repairs with cross-lock sizes of 2 and 4 mm provide high tensile strength and are resistant to pullout. Repairs with 4-mm cross-locks tend to provide a more central load distribution and better gapping resistance than repairs with 2-mm cross-locks.

Flexor tendon repair using a new suture technique: a comparative in vitro biomechanical study

INTRODUCTION

The purpose of this experimental study was to evaluate the biomechanical characteristics of two new four-strand core suture techniques for flexor tendon repair.

MATERIALS AND METHODS

The two new suture techniques (Marburg 1, Marburg 2) are characterized by four longitudinal stitches which are anchored by a circular or semicircular suture. They were compared with three commonly used core suture techniques (modified Kessler, Tsuge, Bunnell). Fifty porcine flexor tendons were randomly assigned to one of the five core suture techniques. Outcome measures included ultimate tensile strength, maximum of lengthening, mode of failure and 1 mm gap formation force.

RESULTS

The highest ultimate tensile strength was found for the modified Kessler technique (115 N). Both new techniques showed an ultimate load exceeding 50 N (57 N for Marburg 1, 54 N for Marburg 2). The Marburg 1 technique showed the highest gap resistance of all tested suture techniques. The Bunnell and Tsuge core suture techniques produced the poorest mechanical performance.

CONCLUSION

From these experimental results, the new Marburg 1 core suture technique can be considered for flexor tendon repair in a clinical setting with the use of active motion protocols.

Biomechanical comparisons of four-strand tendon repairs with double-stranded sutures: effects of different locks and suture geometry

Multi-strand repairs are often used in flexor tendon surgery. We evaluated the strength of four four-strand tendon repairs with different locks and suture geometry. Forty-eight pig flexor tendons were repaired with the following methods: a cross-lock four-strand repair; a U-shaped repair with circle-locks; a modified Kessler repair with Pennington locks (with longitudinal sutures located more centrally; and another modified Kessler (with longitudinal sutures located more laterally). The tendons were loaded to complete failure of the repairs. The two Kessler repairs showed a 35% lower 2 mm gap force, and 15% lower ultimate strength compared with the other two repairs; the differences were of statistical significance. The failure pattern was breakage of sutures in almost all tendons. These four-strand repairs differed in gapping and ultimate strengths. The Kessler-type repairs with different geometry in the longitudinal sutures produced identical strengths. The Kessler-type repairs with Pennington locks were weaker than the two repairs with either cross-locks or circle-locks.

The Bio-Tribological Characteristics of Synthetic Tissue Grafts

The use of synthetic connective tissue grafts became popular in the mid-1980s, particularly for anterior cruciate ligament reconstruction; however, this trend was soon changed given the high failure rate due to abrasive wear. More than 20 years later, a vast range of grafts are available to the orthopaedic surgeon for augmenting connective tissue following rupture or tissue loss. While the biomechanical properties of these synthetic grafts become ever closer to the natural tissue, there have been no reports of their bio-tribological (i.e. bio-friction) characteristics. In this study, the bio-tribological performance of three clinically available synthetic tissue grafts, and natural tendon, was investigated. It was established that the natural tissue exhibits fluid-film lubrication characteristics and hence is highly efficient when sliding against opposing tissues. Conversely, all the synthetic tissues demonstrated boundary or mixed lubrication regimes, resulting in surface—surface contact, which will subsequently cause third body wear. The tribological performance of the synthetic tissue, however, appeared to be dependent on the macroscopic structure. This study indicates that there is a need for synthetic tissue designs to have improved frictional characteristics or to use a scaffold structure that encourages tissue in-growth. Such a development would optimize the bio-tribological properties of the synthetic tissue and thereby maximize longevity.

The effects of core suture purchase on the biomechanical characteristics of a multistrand locking flexor tendon repair: a cadaveric study

PURPOSE

To determine the effects of suture purchase on work of flexion (WOF), 2-mm gap force, and load to failure on the combination cross-locked cruciate-interlocking horizontal mattress (CLC-IHM) flexor tendon repair in zone II.

METHODS

A total of 33 fresh-frozen cadaveric fingers were mounted in a custom jig, and the flexor digitorum profundus of each finger was fixed to the mobile arm of a tensile strength machine. Initial measurements of WOF were obtained. Each tendon was repaired with the CLC core suture, randomly assigned to placement of 3, 5, 7 or 10 mm from the cut edge of the tendon, and completed with the IHM circumferential suture. After the repair was completed, measurements of WOF were repeated. Each finger was cycled 1000 times. After each 250 cycles, gapping was recorded, and WOF was measured again. Change in WOF (WOF after repair - WOF of intact tendon) was calculated. Tendons were then dissected from the fingers and linearly tested for 2-mm gap force and ultimate load to failure.

RESULTS

The group repaired at 10 mm had the lowest percent increase in WOF (5.2%), the highest 2-mm gap force (89.8 N), and the highest ultimate load to failure (111.5 N). The group repaired at 3 mm had the highest percent increase in WOF (22.1%), the lowest 2-mm gap force (54.6 N), and the lowest ultimate load to failure (84.6 N).

CONCLUSIONS

A 10-mm suture purchase is the recommended distance for optimal performance for the CLC-IHM combination repair method. This method with a 10-mm suture purchase has a low increase in WOF, high strength, and high resistance to gapping, and it should be strong enough to tolerate early motion.

The four-strand staggered suture for flexor tendon repair: in vitro biomechanical study

PURPOSE

To assess in vitro biomechanical properties of a 4-strand flexor tendon suture compared to 3 established suture techniques. This technique, which is made of 2 alternating and staggered sutures, one external to the tendon and the other internal, must be sufficiently resistant to withstand loads applied by modern, early active mobilization protocols.

METHODS

Forty flexor hallucis longus tendons were harvested from fresh cadavers, cut, and repaired using 4 different suture techniques (Strickland, Wolfe, modified Savage, and a new technique called 4-strand staggered). All repaired tendons were submitted to static loading trials to measure gap formation (2 mm) in relation to tensile force and breaking force of all 4 sutures. Twenty additional tendons were repaired with the new suture technique and submitted to dynamic trials under cyclic loading.

RESULTS

The 4-strand staggered suture technique proved to be statistically superior to Strickland and modified Savage techniques following the static loading trials for gap formation and breaking force. This technique is statistically superior to the Wolfe cruciate suture for breaking force and superior but not statistically significant for gap formation. The dynamic loading trials have shown that the 4-strand staggered suture can tolerate in vitro loads similar to those exerted by modern, early active mobilization protocols.

CONCLUSIONS

The suture technique created by the authors proved to hold superior biomechanical properties than the other techniques tested in this study and might be suitable for early active mobilization protocols.

Strength of tendon repair decreases in the presence of an intact A2 pulley: biomechanical study in a chicken model

PURPOSE

Pulleys have an important role in digital flexion, but little is known about how the strength of a tendon repair is affected by a major pulley. We evaluated the difference in strengths of flexor tendon repairs in the pulley area when the pulley was intact or divided in a chicken tendon injury model.

METHODS

In each of 100 long toes of 50 Leghorn chickens, a complete, transverse laceration of the flexor digitorum profundus tendon was made in the region of the A2 pulley and was repaired surgically. The A2 pulley was preserved or was completely divided longitudinally. The toes were harvested by disarticulating through the knee joint, and placed at full extension, at 20 degrees , 40 degrees , or 60 degrees of distal interphalangeal (DIP) joint flexion, and at 40 degrees , 80 degrees , or 120 degrees of combined DIP and proximal interphangeal (PIP) joint flexion, and tendon repairs were loaded to failure in a materials testing machine. The force required for ultimate failure was statistically compared for each group.

RESULTS

Ultimate tendon repair strength was significantly lower in toes with the A2 pulley intact than in those with the pulley vented when the toes were placed at full extension and at all tested degrees of DIP and PIP joint flexion, except at the most marked flexion. After A2 pulley division, tendon repair strength was 30% to 60% higher than flexed toes with the pulley intact. With an intact pulley, the tendon repair strength in the flexed toes was significantly lower than that in the fully extended toes, but after A2 pulley division, the strength was similar at all toe positions except at the most marked flexion.

CONCLUSIONS

Chicken tendon repairs are substantially weaker when the A2 pulley is intact than when the pulley is completely divided. Loading of the tendon repair against an intact major pulley adversely affects repair strength. These findings suggest that tendon repair is less likely to fail when the A2 pulley is divided than when the pulley is intact; pulley venting may decrease the likelihood of repair ruptures.

Tendon injuries in the pediatric hand

Injuries to the flexor and extensor tendons in the hand are common and require cautious evaluation and treatment or repair. Flexor tendon injuries are often associated with neurovascular injury and thus must be considered in the differential workup. Extensor injuries may involve intra-articular damage, which must also be identified. The diagnosis and management of common flexor and extensor tendon injuries of the hand are described.

Evaluation of simple and looped suture and new material for flexor tendon repair

Flexor tendon repair strength is proportional to the number of suture strands crossing the repair site but it is not clear if each strand needs to result from a separate pass through the tendon. We examined whether one throw of looped suture across a repair site equals two separate throws of suture and whether fewer passes with stronger material such as Fiberwire is equivalent to more passes with a comparatively weaker material such as Supramid. When evaluating the repairs for force required to generate a 2 mm gap and for gap formed at the instant prior to failure, looped suture cannot substitute for two separate passes of suture (Supramid Kessler looped vs. separate passes, 14 N vs. 35 N and 8.8 mm vs. 4.1 mm, respectively; Fiberwire Kessler looped vs. separate passes, 25 N vs. 43 N and 7.6 mm vs. 4.6 mm, respectively; all p<0.05). Two-stranded Fiberwire Kessler repair equalled four-stranded cruciate repair with Supramid for all tested parameters (force at 2 mm gap: 17 N vs. 22 N, respectively; force at failure: 42 N vs. 46 N; and gap formed prior to instant of failure: 6.9 mm vs. 5.6 mm; all p>0.05).

Comparison of 1- and 2-knot, 4-strand, double-modified kessler tendon repairs in a porcine model

PURPOSE

To compare 1- and 2-knot, 4-strand, double-modified Kessler tendon repairs. It was our hypothesis that a 1-knot technique using an unbraided suture material would be stronger if it is possible for some movement to occur between strands on loading, redistributing forces such that the load is equally shared.

METHODS

Fifty-six porcine flexor tendons were allocated to either a 1- or 2-knot, 4-strand, double-modified Kessler repair, and tested by incremental cyclical loading in vitro.

RESULTS

The 1-knot technique was significantly stronger. Gap formation was initially greater in the 1-knot group, consistent with movement of strands, but with increasing physiological levels of applied force, there was no significant difference between the groups.

CONCLUSIONS

The 1-knot technique was significantly stronger than the 2-knot technique.

Hand replantation with proximal row carpectomy

The purpose of this study is to present our operative technique and postoperative results of the hand replantation with proximal row carpectomy in cases of complete amputation at the level of wrist joint. From May 2003 to April 2005, five patients suffered from complete amputation of the hand due to industrial trauma. Amputation level was radiocarpal joint in three cases and midcarpal joint in two cases. Three cases represented guillotine type and two cases with local crush type injuries. All were men and the mean age was 26.6 years. The mean follow-up period was 26.8 months. At the time of replantation, the wrist joint was stabilized with transarticular fixation using three to four Kirschner's wires after performing proximal row carpectomy. Postoperatively, functional results such as muscle strength, range of motion of the wrist and fingers, and sensory recovery were assessed according to Chen's criteria. Joint width and arthritic changes of the radio-capitate joint were evaluated with radiologic tools. According to Chen's criteria, the overall results in five cases were classified as grade II. Intrinsic muscle power of hands was found to be grade 4. The mean grip and pinch powers were 41% and 45%, respectively, compared to contralateral hand. The mean arc of flexion-extension of wrist was 53 degrees . Total mean active motion of fingers was 215 degrees. Static two-point discrimination of fingertip ranged from 8 to 13 mm. On the follow-up, computerized tomography showed well-preserved radio-capitate joint space without any arthritic changes. While performing hand replantation after amputation at the radiocarpal or midcarpal level, proximal row carpectomy is a useful procedure to preserve joint motion of the wrist in selected cases.

Biomechanical study of cross-locked cruciate versus Strickland flexor tendon repair

PURPOSE

Zone II flexor tendon repairs may create a bulging effect with resistance to tendon gliding. A biomechanical study was performed comparing the 4-strand cross-locked cruciate (CLC) to a 4-strand Strickland repair, both with and without an interlocking horizontal mattress (IHM) suture, in terms of strength characteristics and work of flexion.

METHODS

Sixteen fresh-frozen human fingers were placed in a custom jig. Flexor digitorum profundus tendons were sectioned at the A3 pulley level. Fingers were separated into 2 repair groups: 4-strand CLC and 4-strand Strickland core suture. Work of flexion was determined for each group, with and without an IHM circumferential suture. Final repair including IHM was tested for 2-mm gap failure and ultimate load to failure.

RESULTS

The CLC-IHM had a significantly smaller increase in work of flexion than the Strickland-IHM. For both suture types, the circumferential suture resulted in a statistically significant increase in work of flexion; however, peak entry force produced upon entry of the repair into the A2 pulley was reduced, although the decrease was not statistically significant for each group. The CLC-IHM had a significantly higher ultimate load to failure.

CONCLUSIONS

(1) The CLC-IHM suture method is stronger with less work of flexion than the Strickland-IHM method. (2) This new, combination repair method of CLC core suture with IHM circumferential suture is biomechanically superior to the commonly performed Strickland-IHM technique.

Does strand configuration and number of purchase points affect the biomechanical behavior of a tendon repair? A biomechanical evaluation using different kessler methods of flexor tendon repair

This study compares the mechanical properties of modified Kessler and double-modified Kessler flexor tendon repair techniques and evaluates simple modifications on both methods. Forty fresh sheep flexor tendons were divided equally into four groups. A transverse sharp cut was done in the middle of each tendon and then repaired with modified Kessler technique, modified Kessler with additional purchase point in the midpoint of each longitudinal strand, double-modified Kessler technique, or a combination of outer Kessler and inner cruciate configuration based on double-modified Kessler technique. The tendons were tested in a tensile testing machine to assess the mechanical performance of the repairs. Outcome measures included gap formation and ultimate forces. The gap strengths of the double-modified Kessler technique (30.85 N, SD 1.90) and double-modified Kessler technique with inner cruciate configuration (33.60 N, SD 4.64) were statistically significantly greater than that of the two-strand modified Kessler (22.56 N, SD 3.44) and modified Kessler with additional purchase configuration (21.75 N, SD 4.03; Tukey honestly significant difference test, P < 0.000). There were statistically significant differences in failure strengths of the all groups (analysis of variance, P < 0.000). With an identical number of strands, the gap formation and ultimate forces of the repairs were not changed by additional locking purchase point in modified Kessler repair or changing the inner strand configuration in double-modified Kessler repair. The results of this study show that the number of strands across the repair site together with the number of locking loops clearly affects the strength of the repair; meanwhile, the longitudinal strand orientation and number of purchase points in a single loop did not affect its strength.

Comparative biomechanic study of flexor tendon repair using FiberWire

PURPOSE

FiberWire, an increasingly popular suture material, allows for strong flexor tendon repair that may allow early mobilization. This study was designed to evaluate the mechanical characteristics of FiberWire for flexor tendon repair and to identify the most effective repair technique using this material.

METHODS

Forty-nine human cadaver flexor tendons were randomized and tested biomechanically using one of the following techniques of flexor tendon repair performed with 3-0 FiberWire: (1) modified Kessler, (2) modified Pennington, (3) 2-strand multiple grasping, (4) 2-strand multiple locking, (5) 2-strand double cross-locks, (6) Massachusetts General Hospital, and (7) 4-strand locked cruciate. The ultimate tensile strength, 2-mm gap resistance, and failure mode of the repairs were evaluated.

RESULTS

Knot unraveling was the most common failure mode of FiberWire repair in 4 of the 7 techniques. Four-strand repairs and locking repairs provided significantly more strength than 2-strand repairs and grasping repairs. Multiple grasping and multiple locking repairs with 2 knots were significantly weaker than single grasping and locking repairs with a single knot. Four-strand locked cruciate repairs were significantly stronger than the other techniques (mean ultimate tensile strength 107 N, 2-mm gap force 96 N). Two-strand double cross-locks repairs were stronger than the other 2-strand repairs (mean ultimate tensile strength 69 N, 2-mm gap force 53 N).

CONCLUSIONS

The strength of the FiberWire repairs increased with locking repair and with increased number of strands but was not influenced by increased number of locking and grasping stitches. Four-strand locked cruciate and 2-strand double cross-locks provided the greatest strength and likely are appropriate for future clinical use in, respectively, 4-strand and 2-strand repairs. However, the poor knot-holding characteristics of FiberWire with the need of a greater number of knot throws may be of concern for surgeons using this product for flexor tendon repairs.