Comparison of pullout button versus suture anchor for zone I flexor tendon repair

PURPOSE: To evaluate the clinical outcome after repair of zone I flexor tendon injuries using either the pullout button technique or suture anchors placed in the distal phalanx. METHODS: Between 1998 and 2002 we treated 26 consecutive zone I flexor tendon injuries. Thirteen patients had repairs from 1998 to 2000 using a modified pullout button technique (group A) and 13 patients had repair using suture anchors placed in the distal phalanx (group B). Patient characteristics were similar for both groups. The same postoperative flexor tendon rehabilitation protocol and follow-up schedule were used for both groups. Evaluation included range of motion, sensibility and grip strength, failure, complications, and return to work. The Student t test was used to determine significant differences. RESULTS: All patients completed 1 year of follow-up evaluation. There were 2 infections in group A that resolved with oral antibiotics and no infections in group B. There were no tendon repair failures and no repeat surgeries in either group. At final follow-up evaluation there were no statistically significant differences for the following end points: sensibility (Semmes-Weinstein monofilament testing and 2-point discrimination), active range of motion (at the proximal interphalangeal joint, distal interphalangeal joint, or their combined motion), flexion contracture (at the proximal interphalangeal joint, distal interphalangeal joint, or their combined contracture), and grip strength (injured tendon as a percent of the contralateral uninjured tendon). The suture anchor group had a statistically significant improvement for time to return to work. CONCLUSIONS: There was no significant difference in the clinical outcome after flexor tendon repair using either suture anchors or the pullout button technique. A significant improvement was found for time to return to work for repairs using the suture anchor technique. Flexor tendon repair can be achieved using suture anchors placed in the distal phalanx, thereby avoiding the potential morbidity associated with the pullout button technique. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level III.     

Primary repair of a flexor tendon after a human bite

Successful uncomplicated primary closure of a human bite injury of the hand with simultaneous zone II flexor tendon injury has not been previously reported to our knowledge. We report the case of a man who was bitten on his left ring and right middle and index fingers. He was treated with antiseptic lavage, intravenous antibiotics, and operation. He had complete transsection of the flexor digitorum profundus at the middle phalanx. This was repaired primarily and he made a good recovery.     

Flexor tendon repair in zone II with 6-strand techniques and early active mobilization

PURPOSE: There are many biomechanic studies of 6-strand suture techniques for active mobilization, but few reports have described the clinical outcome in zone II flexor tendon lacerations. We discuss the clinical results of zone II flexor tendon repair using 2 of these techniques followed by controlled early active mobilization. METHODS: Six-strand sutures using the number 1 technique by Yoshizu or a triple-looped suture technique were used to repair flexor tendons in 27 fingers from 21 consecutive patients. Fingers were mobilized by combining active extension and passive or active flexion in a protective splint for the first 3 weeks after surgery. The follow-up period averaged 13 months. RESULTS: Based on the original Strickland criteria, the results were excellent in 17 fingers, good in 9, and fair in 1. The average flexion was 62 degrees for distal interphalangeal joints and 91 degrees for proximal interphalangeal joints. None of the repaired tendons ruptured. CONCLUSIONS: The 6-strand flexor tendon suture technique followed by controlled active mobilization protected with a dorsal splint is safe, produces no ruptures, and achieves very good results in zone II flexor tendon laceration repair. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic, Level II.     

A comparative analysis of the biomechanical behaviour of five flexor tendon core sutures

Five core suture techniques were compared by static tensile testing in vitro. Fifty porcine tendons were used. The core sutures were performed with 3-0 or 4-0 braided polyester suture (Ticron) and the over-and-over running peripheral sutures with 6-0 monofilament polypropylene (Prolene). The core sutures were: (1) Pennington modified Kessler (3-0), (2) Double Pennington modified Kessler (3-0), (3) 4-strand Savage (3-0), (4) 4-strand Savage (4-0), and (5) 6-strand Savage (4-0). Repairs were compared as paired in regard to one variable: the number of core suture strands, the suture calibre, or the suture configuration. Biomechanical differences between the repair groups started during the linear region, with the yield force and stiffness increasing along with the number of core suture strands. All three variables influenced the strain at the yield point. Thus, the strength of the intact repair can be improved by modifying the core suture. In all repairs gap formation started near the yield point after failure of the peripheral suture. The yield force represents the strength of the intact repair composite and should be considered the strength of the tendon repair.     

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

Purpose

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

Methods

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

Results

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

Conclusions

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

Surface modification counteracts adverse effects associated with immobilization after flexor tendon repair

Although post‐rehabilitation is routinely performed following flexor tendon repair, in some clinical scenarios post‐rehabilitation must be delayed. We investigated modification of the tendon surface using carbodiimide derivatized hyaluronic acid and lubricin (cd‐HA‐Lub) to maintain gliding function following flexor tendon repair with postoperative immobilization in a in vivo canine model. Flexor digitorum profundus tendons from the 2nd and 5th digits of one forepaw of six dogs were transected and repaired. One tendon in each paw was treated with cd‐HA‐Lub; the other repaired tendon was not treated. Following tendon repair, a forearm cast was applied to fully immobilize the operated forelimb for 10 days, after which the animals were euthanized. Digit normalized work of flexion (nWOF) and tendon gliding resistance were assessed. The nWOF of the FDP tendons treated with cd‐HA‐Lub was significantly lower than the nWOF of the untreated tendons (p < 0.01). The gliding resistance of cd‐HA‐Lub treated tendons was also significantly lower than that of the untreated tendons (p < 0.05). Surface treatment with cd‐HA‐Lub following flexor tendon repair provides an opportunity to improve outcomes for patients in whom the post‐operative therapy must be delayed after flexor tendon repair. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1940–1944, 2012     

An experimental study of the repair and gliding function of digital flexor tendon following injury

Summary The profundus tendons of young adult chickens have been used to study flexor tendon healing within the digital sheath. Histological observation has shown that the preserved digital sheath prevented the tendon healing with adhesions and that the epitendon played a leading role in the process of tendon repair. Muscle tension must be removed from the sutured site for tendon repair without adhesion. Post-operative immobilisation in the tension-reducing position, in which an operated digit is flexed and the rest of the digits are extended, is believed to be one of the most efficient procedures for removing tension from the sutured site of the tendon. Three methods of tendon suture were used — Bunnell crisscross stitch, modified double right-angle suture, and interrupted suture. Least adhesions were noted in the tendons sutured by interrupted suture, and the tensile strength of the tendons sutured by interrupted suture tended to be highest between three and six weeks postoperatively. To achieve tendon healing with good gliding function, the following procedures should be observed: (1) preservation of the digital sheath, (2) an atraumatic technique for tendon suture, and (3) immobilisation in the tension-reducing position.

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Résumé On a utilisé le tendon fléchisseur profond du poulet pour étudier la cicatrisation des tendons fléchisseurs des doigts à l'intérieur de la gaine digitale. Les examens anatomo-pathologiques ont montré que la conservation de la gaine évitait la formation d'adhérences et que l'épitendon jouait un rôle majeur dans le processus de réparation du tendon, en l'absence de ces adhérences.Pour obtenir cette cicatrisation sans adhérences, il faut supprimer toute tension en regard de la zone suturée. L'immobilisation post-opératoire dans une position de relâchement, le doigt opéré étant fléchi et les autres étendus, paraît être un des meilleurs procédés pour supprimer cette tension.Parmi les trois méthodes de suture tendineuse: laçage à la Sterling Bunnell, suture modifiée à double angle droit et suture à points séparés, c'est cette dernière qui donne le moins lieu à la formation d'adhérences. Et c'est entre la 3ème et la 6ème semaine post-opératoire que la résistance à la traction du tendon ainsi suturé est la plus élevée.Pour obtenir la cicatrisation tendineuse avec une bonne récupération fonctionnelle, les points de technique suivants sont donc essentiels: (1) préservation de la gaine digitale, (2) technique atraumatique de suture du tendon et (3) immobilisation du doigt en position de relâchement.

     

Stress relaxation and creep: viscoelastic properties of common suture materials used for flexor tendon repair

PURPOSE: The time-dependent mechanical behavior of common suture materials may have a pronounced influence on the quality of flexor tendon repairs with respect to gap formation. METHODS: Sutures commonly used in plastic surgery, particularly for hand tendon repair, were tested in tension for analysis of stress relaxation and creep properties. The three materials tested were (1) Prolene, a monofilament polypropylene(Ethicon, Somerville, NJ); (2) Ethilon, a monofilament nylon(Ethicon, Somerville, NJ); and (3) Ticron, a braided polyester fiber (Sherwood, Davis & Geck, St. Louis, MO). All measurements were made with 1.5-mm (4-0) varieties of the sutures, in physiological buffered solution (0.9% phosphate-buffered saline [PBS]) at both room (22 degrees C) and body temperature (37 degrees C) conditions. RESULTS: Ticron was the stiffest suture at both room and body temperature, followed by Prolene and Ethilon. Both Prolene and Ethilon showed statistically (p< .05) reduced stiffness at body temperature. Prolene exhibited statistically larger (p< .05) relaxation and creep ratios than the other two sutures, and it was the only material to show temperature effects in creep and relaxation. CONCLUSIONS: Based on static and viscoelastic mechanical properties, Ticron is the most suitable suture for flexor tendon repairs when compared to Prolene and Ethilon.     

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.     

Distal attachment of flexor tendon allograft: A biomechanical study of different reconstruction techniques in human cadaver hands

We compared the mechanical force of tendon‐to‐bone repair techniques for flexor tendon reconstruction. Thirty‐six flexor digitorum profundus (FDP) tendons were divided into three groups based upon the repair technique: (1) suture/button repair using FDP tendon (Pullout button group), (2) suture bony anchor using FDP tendon (Suture anchor group), and (3) suture/button repair using FDP tendon with its bony attachment preserved (Bony attachment group). The repair failure force and stiffness were measured. The mean load to failure and stiffness in the bony attachment group were significantly higher than that in the pullout button and suture anchor groups. No significant difference was found in failure force and stiffness between the pullout button and suture anchor groups. An intrasynovial flexor tendon graft with its bony attachment has significantly improved tensile properties at the distal repair site when compared with a typical tendon‐to‐bone attachment with a button or suture anchor. The improvement in the tensile properties at the repair site may facilitate postoperative rehabilitation and reduce the risk of graft rupture. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1720–1724, 2013     

Gliding resistance of flexor tendon associated with carpal tunnel pressure: A biomechanical cadaver study

The purpose of this study was to investigate the effect of carpal tunnel pressure on the gliding characteristics of flexor tendons within the carpal tunnel. Eight fresh human cadaver wrists and hands were used. A balloon was inserted into the carpal tunnel to elevate the pressure. The mean gliding resistance of the middle finger flexor digitorum superficialis tendon was measured with the following six conditions: (1) as a baseline, before balloon insertion; (2) balloon with 0 mmHg pressure; (3) 30 mmHg; (4) 60 mmHg; (5) 90 mmHg; (6) 120 mmHg. The gliding resistance of flexor tendon gradually increased as the carpal tunnel pressure was elevated. At pressures above 60 mmHg, the increase in gliding resistance became significant compared to the baseline condition. This study helps us to understand the relationship between carpal tunnel pressure, which is elevated in the patient with carpal tunnel syndrome (CTS) and tendon gliding resistance, which is a component of the work of flexion. These findings suggest that patients with CTS may have to expend more energy to accomplish specific motions, which may in turn affect symptoms of hand pain, weakness and fatigue, seen commonly in such patients. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:58–61, 2011     

The strength of the 6-strand modified Kessler repair performed with triple-stranded or triple-stranded bound suture in a porcine extensor tendon model: an ex vivo study

PURPOSE: To investigate the biomechanic influence of triple-stranded sutures and the spatial arrangement of the strands on the strength of the 6-strand Pennington modified Kessler repair. METHODS: In the present ex vivo study of pig extensor tendons 2 techniques were used: (1) triple-stranded suture (3 suture strands in the same needle) and (2) triple-stranded bound suture (3 suture strands in the same needle that were bound together, parallel to each other, side by side). The repairs were subjected to static tensile testing. RESULTS: The 6-strand modified Kessler repair performed with triple-stranded bound suture reached significantly higher yield force, ultimate force, and both partial and total 1-, 2-, and 3-mm gap forces compared with the repairs performed with triple-stranded suture. The stiffness and strain values at the yield point and at the ultimate point did not differ significantly. CONCLUSIONS: This experimental study introduces a way to improve the strength of the tendon repair. The triple-stranded bound suture significantly increased both the gap resistance and ultimate force of the 6-strand modified Kessler repair. We assume the improvements are due to increased holding capacity of the locking loops. The triple-stranded bound suture is easy to use and avoids several problems associated with traditional multistrand repairs. Further studies are needed before clinical use can be considered.     

A biomechanical analysis of a new interlock suture technique for flexor tendon repair.

Using a computerised tensometer, both the gap-producing and breaking forces of a new interlocking suture for flexor tendon repair were compared to the modified Kessler and the Strickland techniques. 30 porcine deep flexor tendons were used in each group and all repairs were performed with 3/0 polypropylene sutures. The interlock technique withstood gap-producing and breaking forces significantly better than the modified Kessler and Strickland techniques. Also, the gap-producing force was closer to the breaking force with the interlock technique than with the other two techniques.     

A six-strand technique for zone II flexor-tendon repair in children younger than 2 years of age

Introduction

A six-strand repair for zone II flexor-tendon repair in children younger than 2 years of age has not been reported in the literature because of the small size of the flexor tendon in this very young age group.

Purpose

The aim is to introduce the use of a six-strand repair in zone II flexor-tendon repair in children younger than 2 years of age.

Methods

A total of 12 children younger than 2 years, with 12 injured fingers, were treated over a 10-year period. A ‘profundus only’ repair was done using three separate ‘figure of eight’ core sutures and a continuous epitendinous suture. The repair site was bulky and ‘venting’ of the pulley system proximal to the repair site was done. The hand was immobilised for 3.5 weeks after surgery and then physiotherapy exercises were started. The final net range of motion at the interphalangeal joints was measured and the outcome was assessed as per the Strickland-Glogovac criteria.

Results

There were no ruptures. The final outcome in range of motion was excellent in nine children and good in the remaining three children. None of the children required tenolysis.

Conclusion

Our six-strand technique is an alternative technique for zone II flexor-tendon repair in children younger than 2 years of age, but the bulky repair site requires a ‘profundus only’ repair and ‘venting’ of the pulley system.