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

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Rehabilitation following flexor tendon injury in Zone 2: a randomized controlled study

The aim of this study was to compare an early active motion (EAM) regimen to a modified Kleinert passive motion therapy in Zone 2 flexor tendon injuries with regards to range of motion (ROM), grip strength and patient-reported outcome measures (PROMs). Seventy-two patients were included. At 3 months postoperatively, we found no difference in total active motion (TAM) between the EAM and the Kleinert groups (median 195.5°, range 115°-273° versus median 191.5°, range 113°-260°), but a significantly better grip strength (median 76%, range 44%-99% versus median 54%, range 19%-101%; p < 0.0005) in the EAM group. Disabilities of the Arm, Shoulder and Hand (DASH) score as well as patient-reported weakness, cold intolerance and problems in daily activities also favoured the EAM group. At 12 months postoperatively, there was no difference in TAM, grip strength or any of the PROMs used. We conclude that EAM leads to a quicker recovery in terms of grip strength and PROMs, but that both regimens lead to similar results at 12 months.Level of evidence: I.

Reoperation Following Zone II Flexor Tendon Repair

BACKGROUND

The goal of zone II flexor tendon surgery is to perform a repair with sufficient strength to withstand the forces encountered during rehabilitation. Postoperative rerupture and adhesion formation may lead to reoperation. This study aimed to determine the factors associated with reoperation after primary zone II flexor tendon repair.

METHODS

In this retrospective case series, a total of 252 fingers in 201 patients underwent zone II flexor tendon repair. A medical record review was performed to collect data regarding patient demographics, injury and treatment characteristics and postoperative complications including reoperation. Reoperation was defined as any unplanned surgical procedure performed after initial flexor tendon repair.

RESULTS

There were 49 fingers (19%) in 42 patients that underwent reoperation at a median of 5.5 (interquartile range: 2.8-7.9) months. Older age, workers' compensation, and a Kessler-type repair of the flexor digitorum profundus were independently associated with reoperation.

CONCLUSIONS

In vitro studies suggest that Kessler-type repairs are inferior compared with other suture configurations. Our study demonstrates a clinical correlation to these biomechanical studies. Our results suggest that Kessler-type repairs are inferior compared with non-Kessler-type repairs, due to postoperative complications requiring secondary surgeries.

Rupture Rate, Functional Outcome and Patient Satisfaction after Primary Flexor Tendon Repair with the Modified 4-Strand Core Suture Technique by Tsuge and Using the Arthrex FiberLoop® with Early Motion Rehabilitation

PURPOSE

Our hypothesis was that the rupture rate after primary flexor tendon repair in the modified 4-strand core suture technique using the FiberLoop^® (Arthrex, Munich, Germany) is lower than in other suture materials and functional outcome and patient satisfaction are superior compared to the current literature.

PATIENTS AND METHODS

A 2-stage retrospective, randomized follow-up study of 143 patients treated with the Arthrex FiberLoop^® after flexor tendon injury in zones 2 or 3 from May 2013 to May 2017 was performed. In the 1^st stage, the rupture rate of all patients was assessed after a follow-up of at least one year by interview to exclude revision surgery. In the 2nd stage, 20% of the patients could be randomly clinically examined. Functional parameters, such as finger and wrist range of motion measured by goniometer, grip strength measured by Jamar dynamometer (Saehan, South Korea), patient satisfaction measured by school grades (1-6), pain levels measured by visual rating scales (0-10) and functional outcome according to the DASH-score were assessed. The Buck-Gramcko and Strickland scores were calculated. The length of sick leave was recorded.

RESULTS

A rupture rate of 2.1% was recorded. 29 patients (20%) were followed up at a mean of 34 ± 7.5 months postoperatively. 10.3% of these patients had an incomplete fingertip palm distance. The mean postoperative grip strength was 24 ± 3.1 kg. 93% of the patients were very satisfied with the treatment. No patient complained of pain postoperatively. The mean postoperative DASH score was 6.7 ± 2.8 points. The mean Buck-Gramcko score was 14 ± 0.2 points. 93% of the patients had excellent and 7% good results according to the Strickland score. 67% of patients had a work accident and returned to work at a mean of 4 ± 0.2 months postoperatively. 31% of patients suffered a non-occupational injury and returned to work at a mean of 3 ± 0.4 months postoperatively.

CONCLUSIONS

Primary flexor tendon repair in the modified 4-strand core suture technique using the Arthrex FiberLoop^® has proven to be a viable treatment option in our series. The rupture rate was lower than in other suture materials. It leads to acceptable pain relief, grip strength and functional outcome.

LEVEL OF EVIDENCE

IV; therapeutic.

Use of a Virtual Reality Simulator for Tendon Repair Training: Randomized Controlled Trial

Background

Virtual reality (VR) simulators have become widespread tools for training medical students and residents in medical schools. Students using VR simulators are provided with a 3D human model to observe the details by using multiple senses and they can participate in an environment that is similar to reality.

Objective

The aim of this study was to promote a new approach consisting of a shared and independent study platform for medical orthopedic students, to compare traditional tendon repair training with VR simulation of tendon repair, and to evaluate future applications of VR simulation in the academic medical field.

Methods

In this study, 121 participants were randomly allocated to VR or control groups. The participants in the VR group studied the tendon repair technique via the VR simulator, while the control group followed traditional tendon repair teaching methods. The final assessment for the medical students involved performing tendon repair with the “Kessler tendon repair with 2 interrupted tendon repair knots” (KS) method and the “Bunnell tendon repair with figure 8 tendon repair” (BS) method on a synthetic model. The operative performance was evaluated using the global rating scale.

Results

Of the 121 participants, 117 participants finished the assessment and 4 participants were lost to follow-up. The overall performance (a total score of 35) of the VR group using the KS method and the BS method was significantly higher (P<.001) than that of the control group. Thus, participants who received VR simulator training had a significantly higher score on the global rating scale than those who received traditional tendon repair training (P<.001).

Conclusions

Our study shows that compared with the traditional tendon repair method, the VR simulator for learning tendon suturing resulted in a significant improvement of the medical students in the time in motion, flow of operation, and knowledge of the procedure. Therefore, VR simulator development in the future would most likely be beneficial for medical education and clinical practice.

Trial Registration

Chinese Clinical Trial Registry ChiCTR2100046648; http://www.chictr.org.cn/hvshowproject.aspx?id=90180

A Modified Flexor Tendon Suture Technique Combining Kessler and Loop Lock Flexor Tendon Sutures

OBJECTIVES

In the present study, a novel single knot tenorrhaphy was developed by combining the modified Kessler flexor tendon suture (MK) with the loop lock technique.

METHODS

A total of 48 porcine flexor digitorum profundus tendons were collected and randomly divided into six groups. The tendons were transversely cut and then repaired using six different techniques, the MK method, double knot Kessler-loop lock flexor tendon suture (DK), and single knot Kessler-loop lock flexor tendon suture (SK), each in combination with the epitendinous suture (P), and the same three techniques without P. Furthermore, by performing the load-to-failure tests, the biomechanical properties and the time taken to complete a repair, for each tenorrhaphy, were assessed.

RESULTS

Compared to the MK+P method, DK+P was more improved, thereby enhancing the ultimate tensile strength. The SK+P method, which required fewer knots than DK+P, was easier to perform. Moreover, the SK+P repair increased the force at a 2-mm gap formation, while requiring lesser knots than DK+P.

CONCLUSION

As opposed to the traditional MK+P method, the SK+P method was improved and exhibited better biomechanical properties, which may facilitate early mobilization after the repair.

A Biomechanical Analysis of the Interlock Suture and a Modified Kessler-Loop Lock Flexor Tendon Suture

OBJECTIVE

In this work, we attempted to develop a modified single-knot Kessler-loop lock suture technique and compare the biomechanical properties associated with this single-knot suture technique with those associated with the conventional modified Kessler and interlock suture techniques.

METHODS

In this experiment, a total of 18 porcine flexor digitorum profundus tendons were harvested and randomly divided into three groups. The tendons were transected and then repaired using three different techniques, including modified Kessler suture with peritendinous suture, interlock suture with peritendinous suture, and modified Kessler-loop lock suture with peritendinous suture. Times required for suturing were recorded and compared among groups. The groups were also compared with respect to 2-mm gap load, ultimate failure load, and gap at failure.

RESULTS

For tendon repair, compared with the conventional modified Kessler suture technique, the interlock and modified Kessler-loop lock suture techniques resulted in significantly improved biomechanical properties. However, there were no significant differences between the interlock and modified Kessler-loop lock techniques with respect to biomechanical properties, gap at failure, and time required.

CONCLUSIONS

The interlock and modified Kessler-loop lock techniques for flexor tendon sutures produce similar mechanical characteristics in vitro.

Técnica de sutura tendinosa «un paso, 4-hilos Kessler-Tsuge»

A pesar de haber numerosas técnicas de sutura tendinosa y de no existir un acuerdo general sobre cuál es la mejor, sí hay acuerdo en las características generales que debe tener una buena sutura. Debe ser sencilla su realización, tener nudos bloqueados, conseguir una aposición sin tensión y perfecta de los extremos tendinosos con un mínimo o ningún «gap» en el sitio de la reparación sin producir una lesión de la vascularización del tendón y con una fuerza y resistencia suficientes para permitir una movilización precoz.

En este trabajo presentamos una nueva técnica quirúrgica cuyo diseño sigue 5 principios: (1) cruzar la zona de reparación solo 2 veces para hacer más sencilla la técnica y la aposición perfecta de los cabos tendinosos; (2) conseguir una sutura de 4 hilos de un material resistente; (3) evitar nudos abultados en el sitio de reparación, para facilitar la reparación con el menor material interpuesto; (4) evitar nudos abultados sobre la superficie del tendón, de tal forma que la sutura deslice mejor bajo las poleas; y (5) con una resistencia y fuerza superiores a las admitidas como óptimas.