This review article describes the contribution of Australian authors to the basic science and clinical management of flexor tendon injuries.
Introduction: This study aims to gain a better understanding of current practice for the surgical management and rehabilitation of flexor tendon injuries in Australia, with the intent of establishing common guidelines for training of young surgeons.
Methods: A survey was distributed to the membership of the Australian Hand Surgery Society to determine whether a consensus could be obtained for: suture material and gauge; core and epitenon suture techniques; sheath and pulley management; and post-operative protocols for primary flexor tendon repair.
Results: The predominant materials used for core suture are TicronTM Suture (Tyco Healthcare Group LP, Norwalk, Connecticut, USA) (34%) and EthibondTM Polyester Suture (Ethicon, Somerville, New Jersey, USA) (24%). The two core suture configurations commonly used are the Adelaide (45%) and Kessler (32%) repair. The predominant materials used for epitendinous sutures are 6-0 ProleneTM Polypropylene Suture (Ethicon, Somerville, New Jersey, USA) (56%), 5-0 ProleneTM (21%) and 6-0 EthilonTM Nylon Suture (Ethicon, Somerville, New Jersey, USA) (13%); and the majority (63%) use a running epitendinous technique. The management of critical pulleys is variable, with 89% prepared to perform some release of A2 and A4 pulleys. Rehabilitation protocols vary widely, with 24% of respondents using the same method for all patients, while 76% tailor their approach to each patient. Some component of active motion was used by most.
Discussion: There exists some consensus on the management of flexor tendon injuries in Australia. However, the management of critical pulleys and methods of post-operative rehabilitation remain varied. For the training of young surgeons, a majority advise a 3-0 gauge braided polyester core suture of four strands, combined with a 6-0 ProleneTM simple running epitendinous suture for increased tendon repair strength and smooth glide. Trainees should attempt to retain the integrity of the A2 and A4 pulleys. Post-operative rehabilitation should include a component of active flexion.
Purpose: This study assesses the influence of A2 pulley integrity on the strength of the repair. Method: Part 1- The flexor digitorum profundus (FDP) tendons of 72 Cobb chicken feet were severed and repaired in the region of the A2 pulley using a modified Kessler core suture and an epitendinous suture. The A2 pulley was either left intact, divided for 50% of its length, or divided in its entirety. The distal interphalangeal joint was fixed at a position of 20°, 40° or 60° of joint flexion. The load to failure, integrity of the A2 pulley and the site of tendon failure were analysed. Part 2- A further 32 chicken feet were used to exclude the effects of freezing and thawing on results and to analyse differences when using a core suture only. Results: No difference in failure load between any of the test groups or subgroups was identified. The integrity of the A2 pulley was preserved in all specimens. The most common cause of failure was distal suture pull-out. Discussion: This study does not demonstrate that release of the A2 pulley provides an advantage in increasing tendon repair strength. Division of 50% of the A2 pulley does not predispose to pulley rupture. Flexor tendon repair strength did not alter with distal interphalangeal joint flexion between 20° and 60°. Clinical Relevance: The findings of this study do not support division of the A2 pulley to prevent flexor tendon repair failure if repair methods of appropriate strength are utilised.
Background: The fatigue strength of three peripheral suture techniques for flexor tendon repair was compared by cyclic loading of the repairs in the porcine flexor digitorum tendon.
Methods: Thirty-six tendons were sutured using only peripheral sutures with 6-0 Nylon. An initial cyclic load of 10 N for 500 cycles was applied and increased by 10 N for an additional 500 cycles at each new load until rupture.
Results: The fatigue strength of the symmetric running peripheral suture was 85.0% and 144.8% greater than that of the two kinds of the asymmetric running peripheral sutures.
Conclusions: Symmetric running sutures can enhance the suture strength and appears to be a useful technique for increasing the strength of the peripheral suture.
Background: To propose a new term (‘construct efficiency’) for the evaluation of multi strands flexor tendon repairs using different suture materials.
Methods: A total of twenty specimens from 4-0 braided polyblend sutures (FiberLoop/FiberWire; Arthrex, Naples, FL) and 4-0 nylon sutures (Supramid Extra II; S. Jackson, Inc., Alexandria, VA) were subjected to tensile testing using Pneumatic Cord-and-Yarn Grips (Instron Corp., Canton MA, USA). The ultimate tensile strengths of the suture materials were measured. The expected repair strengths and construct efficiencies were computed based on the experimental results and from available literature on actual repair strengths of the 4-strand Becker, Cruciate repairs and 6-strand Tang, modified Lim-Tsai repairs.
Results: The ultimate tensile strength of nylon suture was 15.4 ± 0.6N, lower than that of braided polyblend suture (45.3 ± 2.3N) with a difference of 194%. The construct efficiency of multi strand repairs varied with respect to different repair techniques and suture materials. It was found that the Becker repairs using FiberWire had the highest construct efficiency (55.7%) followed by the modified Lim-Tsai using Supramid (50.9%), Tang repair using Supramid (49.8%), Cruciate repair using Fiberwire (49.1%), and modified Lim-Tsai repair using FiberLoop (33.5%).
Conclusions: The construct efficiency is more accurate in showing that, in terms of biomechanical strength, the use of FiberWire for the 4-strand Becker and Cruciate repair is more efficient than that of using FiberLoop for 6-strand modified Lim-Tsai repair.
Background: Although flexor tendon injuries cause significant morbidities and socio-economic implications, there have been limited data on patient demographics, injury characteristics and surgical details. The aim of this study is to describe our experience in flexor tendon injuries and repairs.
Methods: We performed a retrospective study of all digital flexor tendon injuries that were repaired from January 2011 to December 2014. The collected data included patient demographics, injury characteristics and surgical details.
Results: A total of 214 patients, 308 digits with 446 flexor tendon repairs were identified. We found that males, non-residents, and 20–29 age group were most prone to flexor tendon injuries. Cleaners, labourers and related occupations were the most vulnerable. The mechanism of injury was usually work-related and mostly caused by glass. Most injuries involve both flexor digitorum profundus and flexor digitorum superficialis tendons. Concomitant digital nerve and vessel injuries were common. Most patients suffered zone 2 laceration of a single digit of the non-dominant hand. Most patients underwent procedures that lasted 1 to 2 hours, including multiple flexor tendon repairs, microsurgical repairs and other interventions.
Conclusions: This study is the largest study on patient demographics, injury characteristics and surgical details on flexor tendon injuries and repairs. It could be used to plan resources and policies for the management and prevention of flexor tendon injuries.
Background: This study evaluated the feasibility of using a low-profile titanium (Ti) plate implant, also known as the Ti-button, for Zone II flexor tendon repair. We hypothesize that the use of the Ti-button can distribute the tensile force on the digital flexor tendons to achieve better biomechanical performance.
Methods: Twenty lacerated porcine flexor tendons were randomly divided into two groups and repaired using Ti-button or 6-strand modified Lim-Tsai technique. Ultimate tensile strength, load to 2 mm gap force, and mode of failure were recorded during a single cycle loading test. We also harvested twelve fingers with lacerated flexor digitorum profundus tendons from six fresh-frozen cadaver hands and repaired the tendons using either Ti-button method or modified Lim-Tsai technique. A custom-made bio-friction measurement jig was used to measure the gliding resistance and coefficient of friction of the tendon sheath interface at the A2 pulley.
Results: The ultimate tensile strength, load to 2 mm gap force, stiffness, and gliding resistance of the Ti-button repairs were 101.5 N, 25.7 N, 7.8 N/mm, and 2.2 N respectively. Ti-button repairs had significantly higher ultimate tensile strength and stiffness than the modified Lim-Tsai repair. However, Ti-button also increased the gliding resistance and coefficient of friction but there was no significant difference between the two repair techniques.
Conclusions: Ti-button repair displayed comparable mechanical properties to the traditional repair in terms of 2-mm gap formation and gliding resistance, but with a stronger repair construct. Thus, this deepened our interest to further investigate the potential of using Ti-button implant in Zone II flexor tendon repair by studying both the mechanical and biochemical (tendon healing) properties in more in-depth.
Background: The holding power of a repaired flexor tendon injury is related to surface sutures, suture material and different techniques. Nowadays, a barbed suture material offers the possibility of knotless flexor tendon repair but many hospitals use non-barbed suture materials. The purpose of this study was to compare a barbed suture material and a non-barbed suture material for primary stability under static loading and increased knots in the non-barbed suture material (knot technique) for increased holding power of tendons in animal testing.
Methods: Forty-five fresh porcine tendons were randomized into three groups: Group 1 (grasping technique group) used a four-strand core suture grasping a four-strand modified Kessler suture by non-barbed suture material [Non-absorbable monofilament polybutester 3–0] was used to repair the tendon with a surgical knot; in Group 2 (knot technique group) a four-strand core suture used the knot technique by non-barbed suture material [Non-absorbable monofilament polybutester 3–0] to repair the tendon with a continuous suture adding surgical knots in the same place as the surgical knot at the repair sites; and Group 3 (knotless technique group) used a four-strand core suture with the knotless technique in modified Kessler suture with barbed suture material [Non-absorbable monofilament polybutester 3–0] to repair the tendon without a knot. Our objective was to compare the ultimate tensile strength between the groups.
Results: The mean tensile strength was 30.38 ± 5.04 N for group 1, 41.71 ± 2.62 for group 2 and 47.53 ± 4.89 for the group 3. The ANOVA test revealed a significant difference among the various techniques (p < 0.05). The highest tensile strength was found in the knotless technique using barbed suture material group.
Conclusions: The knotless technique using barbed suture material demonstrated the highest tensile strength in suture repairs. The maximum tensile strength was significantly higher in this group.
Background: The asymmetric technique for flexor tendon repairs has various advantages but further improvement is possible by using a suitable suture material. In this study, we compare the biomechanical performance of asymmetric repairs using 3 suture materials: Supramid Extra II 4-0, Tendo-Loop 4-0, and FiberLoop 4-0.
Methods: We divided 30 porcine flexor tendons into 3 arms. Each arm of tendons were repaired by using 1 of the 3 proposed suture materials. Each repaired tendon was tested by using a mechanical tester. Ultimate tensile strength (UTS), load to 2 mm gap force, failure mechanism and stiffness of the tendons were investigated.
Results: FiberLoop® achieved the highest UTS (90.4 ± 17.9 N), followed by Tendo-Loop (85.3 ± 10.3 N). The difference was no statistically significant. The UTS of repairs using Supramid® was significantly lower (64.0 ± 8.4 N). For load to 2 mm gap force, FiberLoop® achieved 20.7 ± 4.8 N while Tendo-Loop® had 20.5 ± 4.2 N. The difference was also no statistically significant. The repairs using Supramid® had a significantly lower load to 2 mm gap force of 14.2 ± 2.7 N. The stiffness of asymmetric repairs using FiberLoop® and Tendo-Loop® was 5.64 ± 1.7 N/mm and 5.63 ± 0.7 N/mm. The difference was also no statistically significant. The repairs using Supramid® had a significantly lower stiffness of 4.15 ± 1.0 N/mm. Failure mechanisms for the repaired specimens were reported as such: Supramid had 100% suture rupture; Tendo-Loop had 90% suture rupture and 10% suture pullout; FiberLoop had 20% suture rupture and 80% suture pullout.
Conclusions: The asymmetric repair configuration is able to produce superior biomechanical performance by using Tendo-Loop® or FiberLoop®. Improvement of the asymmetric technique by using Tendo-Loop® or FiberLoop® could potentially contribute to better surgical outcomes of flexor tendon repair.
Background: Outcome reporting following flexor tendon repair has historically concentrated on range of movement. Recently, there has been an increase in the use of patient-reported outcome measures (PROMs). At present, there is no agreed set of outcomes to report following flexor tendon repair. The aim of this study is to review outcome reporting practices after flexor tendon repair in zones 1 and 2.
Methods: A search of Ovid MEDLINE, Ovid EMBASE and Cumulative Index to Nursing and Allied Health Literature (CINAHL) between 1 January 1980 and 31 December 2019 was performed to identify the studies that reported outcomes following the repair of flexor tendons in zones 1 and 2. Study characteristics and data with regard to the reporting of eight outcome domains was extracted: functional outcome (quantitative), functional outcome (subjective), activities of daily living (ADL), satisfaction/quality of life, post-treatment recovery, resources, aesthetics and safety.
Results: A total of 94 out of 4,118 articles identified were included in the review. All studies reported range of motion using 17 different methods of measurement. Eleven studies defined measurement methods incorrectly or unclearly. Only 16 studies reported PROMs, with only one reporting data on assessment of quality of life. Eighteen studies reported time away from employment. Minimal data on resource utilisation and aesthetics were included.
Conclusion: This review highlights wide heterogeneity and paucity of data reporting clinical outcomes of flexor tendon surgery. The development of a core outcome set that would ensure essential outcomes are correctly defined, measured and reported is required.
Level of Evidence: Level IV (Prognostic)
Background: Early active motion protocols have shown better functional outcomes in zone II flexor tendon lacerations. Different techniques of tendon repair have different effects on gliding resistance, which can impact tendon excursion and adhesion formation. For successful initiation of early active mobilisation, the repair technique should have high breaking strength and low gliding resistance. Previous studies have shown the Modified Lim-Tsai technique demonstrates these characteristics. The Asymmetric repair has also shown superior ultimate tensile strength. This study aims to compare the gliding resistance between the two techniques.
Methods: FDP tendons from ten fresh frozen cadaveric fingers were randomly divided into two groups, transected completely distal to the sheath of the A2 pulley and repaired using either the Modified Lim-Tsai or Asymmetric technique. The core repair was performed with Supramid 4-0 looped sutures and circumferential epitendinous sutures were done with nylon monofilament Prolene 6-0 sutures. The gliding resistance and ultimate tensile strength were then tested.
Results: The gliding resistance of the Asymmetric and Modified Lim-Tsai repair techniques were 0.2 and 0.95 N respectively. This difference was significant (p = 0.008). The Modified Lim-Tsai technique had a higher ultimate tensile strength and load to 2 mm gap formation, though this was not significant.
Conclusions: Gliding resistance of the Asymmetric repair is significantly less than that of Modified Lim-Tsai. Ultimate tensile strength and load to 2 mm gap formation are comparable.
Background: The purpose of this study was to report the outcomes of flexor tendon repair in zone II and compare two analytic tests – the original and adjusted Strickland scores – and a global hand function test, the 400-points test.
Methods: We included 31 consecutive patients (35 fingers) with a mean age of 36 years (range 19–82 years) who underwent surgery for a flexor tendon repair in zone II. All patients were treated in the same healthcare facility by the same surgical team. All the patients were followed and evaluated by the same team of hand therapists.
Results: At 3 months after the surgery, we found a good outcome in 26% of patients with the original Strickland score, 66% with the adjusted one and 62% with the 400-points test. Among the 35 fingers, 13 of them were evaluated at 6 months after the surgery. All the scores had improved with 31% good outcomes in the original Strickland score, 77% in the adjusted Strickland score and 87% in the 400-points test. The results were significantly different between the original and adjusted Strickland scores. Good agreement was found between the adjusted Strickland score and the 400-points test.
Conclusions: Our results suggest that flexor tendon repair in zone II remains difficult to assess based solely on an analytic test. It should be combined with an objective global hand function test, such as the 400-points test, which appears to correlate with the adjusted Strickland score.
Level of Evidence: Level IV (Therapeutic)
Tendons are frequently injured by direct trauma. Tendon adhesions were a common sequel of tendon repair and are one of the most challenging problems in hand surgery.
The concept of “controlled motion” gradually replaced “total immobilization” in the treatment of flexor tendon injuries and today represents a standard of care for all primary repaired flexor tendon injury. Use of controlled motion splints during the early stages of stages of tendon recovery in crease tendon gliding. However, how best to achieve passive motion and the effect of passive motion on tendon gliding have remained controversial subjects. Based on a series of recent experiments, the concept of “dynamic synergistic wrist motion splint” was established and evaluated. It was found that this synergistic wrist motion increases the tendon excursion due to eliminating the laxity and buckling of tendon in the regions between pulleys without introduce excessive amount of tension.
The purpose of this study is to design and fabricate a dynamic splint based on this concept and define the nature coordinated motion between the wrist and finger joints due to the passive tension of the muscles in vivo.
Parametric analysis will be conducted to achieve an optimum design with the consideration of anatomic constraints. Clinical trial of using such dynamic splint will be evaluated in the future.
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