Complications after flexor tendon injuries

Revision of Flexor Tendon Repair: Factors Associated With Flexor Tenolysis

BACKGROUND

Tenolysis restores mobility to the flexor tendon through the lysis of adhesions that inhibit and negatively impact functional outcomes following flexor tendon repair. Despite extensive literature on operative techniques and therapy protocols used to minimize adhesion formation, there are limited data examining the association of patient, injury, and postoperative factors with tenolysis. This study aims to: (1) quantify tenolysis rates following flexor tendon repair or reconstruction; and (2) identify patient demographic factors, medical comorbidities, injury characteristics, postoperative diagnoses, and complications associated with tenolysis.

METHODS

PearlDiver was used to identify patients who underwent a flexor tendon repair or reconstruction from 2010 to 2020. Patients were stratified by whether or not flexor tenolysis was performed. Patient demographics, comorbidities, injury characteristics, postoperative diagnoses, and complications were recorded. Logistic regression analysis was used to identify independent risk factors associated with tenolysis.

RESULTS

Database review identified 10 264 patients who underwent either flexor tendon repair or reconstruction, with 612 patients (6.0%) subsequently undergoing tenolysis. Logistic regression analysis determined that vascular injury preceding flexor tendon repair, surgical wound disruption, nerve injury diagnosed postoperatively, postoperative tendon rupture, and need for repeat flexor tendon repair were associated with an increased odds of tenolysis. Patient age, sex, and comorbidities were not associated with performance of tenolysis.

CONCLUSIONS

Although tenolysis rates may differ according to physician and patient preferences, identification of factors associated with tenolysis following flexor tendon repair allows surgeons to risk-stratify patients prior to surgery and help guide postoperative expectations if complications arise.

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.

Complications of flexor tendon repair

This article reviews and highlights complications of flexor tendon repairs. Although the outcomes of flexor tendon repairs have improved over the years, fair or poor functional outcomes are seen, especially in patients whose trauma involves multiple structures of the hand and in zone 5 with multiple tendon lacerations. Rupture of the flexor tendon after repair is no longer a major problem if current repair principles are carefully adhered to. Different degrees of adhesion formations and interphalangeal (IP) joint stiffness still occur in a few patients. Early active postoperative mobilization and use of a shorter splint with sparing of the wrist are effective measures to prevent adhesion formation and IP joint stiffness. Given the overall poor results and high rate of complications with flexor digitorum profundus (FDP) repairs in zone 1, a direct repair of the FDP tendon to any short remnant of the distal insertion with 10-strand or even stronger core suture repair is adopted by many units.

Fabrication and biological properties of artificial tendon composite from medium chain length polyhydroxyalkanoate

Medium chain length polyhydroxyalkanoate (MCL-PHA), a biodegradable and biocompatible material, has a mechanical characteristic of hyper-elasticity, comparable to elastomeric material with similar properties to human tendon flexibility. These MCL-PHA properties gave rise to applying this material as an artificial tendon or ligament implant. In this study, the material was solution-casted in cylinder and rectangular shapes in the molds with the designated small holes. A portion of the torn human tendon was threaded into the holes as a suture to generate a composite tendon graft. The tensile testing of the three types of MCL-PHA/tendon composite shows that the cylinder material shape with the zigzag threaded three holes has the highest value of maximum tensile strength at 56 MPa, closing to the ultimate tendon tensile stress (50-100 MPa). Fibroblast cells collected from patients were employed as primary tendon cells for growing to attach to the surface of the MCL-PHA material to prove the concept of the composite tendon graft. The cells could attach and proliferate with substantial viability and generate collagen, leading to chondrogenic induction of tendon cells. An in vivo biocompatibility was also conducted in a rat subcutaneous model in comparison with medical-grade silicone. The MCL-PHA material was found to be biocompatible with the surrounding tissues. For surgical application, after the MCL-PHA material is decomposed, tendon cells should develop into an attached tendon and co-generated as a tendon graft.

Encircling tendon repair site with collagen sheet in flexor zone 2: retrospective study

BACKGROUND

Peritendinous adhesion is the most common complication of tendon repairs in the hand and often requires surgical intervention, resulting in increased labor loss and increased treatment costs. Many agents used to reduce tendon adhesion in animal models, however these agents have not entered clinical use. This study is the first-ever clinical study that evaluates encircling tendon repair site with collagen sheet as an anti-adhesion barrier.

METHODS

Between December 2014 and January 2020, 156 patients included in this study, with clean cut isolated flexor digitorum profundus (FDP) tendon injury in flexor tendon zone 2. All tendons repaired with modified double Kessler technique. In 76 patients, tendon repair site encircled with collagen sheet. 80 patients were randomly selected from our clinical records and functional results are compared with Strickland's total active motion grading system.

RESULTS

The mean total range of motion was 79% in the control group and 81% in the collagen sheet group, and there was no statistically significant difference between the two groups (Z: - 1.393, p = 0.164). In the control group, very good and good repair according to Strikland classification was 65/80 (81%). In the collagen sheet group, it was 62/76 (82%), respectively. There was statistically significant difference between 5 FDP TAM measurements between collagen sheet and control group (t(35) = 0.29, p = 0.016, p < 0.05). The mean TAM of the 5 FDP tendons in the collagen sheet group: 83.8 (SD: 8.2) in the and 76.1 (SD: 9.5) in the control group.

CONCLUSIONS

For the first time in the literature, functional results of Zone 2 flexor tendon repair using collagen sheets in patients with clean cut tendon injuries reported. However, there were no statistical difference about total active motion between control and collagen sheet group, 5th FDS tendon repairs encircled with collagen sheets had better outcomes. Prospective studies in patient groups with high adhesion risk are recommended.

Relative efficacy of three different tendon repairs in complete flexor digitorum profundus laceration in Zone I: A randomized controlled study

Hand flexor tendon injuries are common and biomechanically challenging to achieve good functional outcomes. Several approaches using the Pennington-modified Kessler repair technique have been attempted, but high-level evidence is still lacking. Here, we evaluated the relative efficacy of three versions of the Pennington-modified Kessler technique in repairing complete flexor digitorum profundus (FDP) laceration in Zone 1. We conducted a 2-year, single-center, double-blind, randomized clinical trial involving 85 patients with 105 digits enrolled between June 1, 2017 and January 1, 2019. Eligible participants were 20-60 years of age and underwent tendon repair in the acute phase for complete FDP laceration distal to the insertion of the superficial flexor tendon. The digits were randomized 1:1:1 to three treatment groups: (1) Pennington-modified Kessler repair; (2) Pennington-modified Kessler repair followed by circumferential tendon suture; or (3) Pennington-modified Kessler repair followed by circumferential epitenon suture. The primary endpoint was total active range of motion (TAROM) at 2 years after the initial surgery. The secondary endpoint was the reoperation rate. Compared with group 1, both techniques for peripheral suture were associated with a decrease in TAROM at 2 years after surgery. The total reoperation rates of the three groups were 11.4%, 18.2%, and 17.6%, and we found no significant differences among the three groups possibly due to the limited sample size. Unexpectedly, among participants with complete FDP laceration in Zone I, both circumferential-tendon and circumferential-epitenon sutures caused worsening of TAROM after 2 years. No conclusions can be drawn regarding reoperation rates among the groups. Level of evidence: Therapeutic level I.

M2 Macrophage Membrane-Mediated Biomimetic-Nanoparticle Carrying COX-siRNA Targeted Delivery for Prevention of Tendon Adhesions by Inhibiting Inflammation

Tendon adhesion is the most common outcome of tendon or tendon-to-bone healing after injury. Our group developed a hydrogel-nanoparticle sustained-release system previously to inhibit cyclooxygenases (COXs) expression and consequently prevent tendon adhesion and achieved satisfactory results. However, effective treatment of multiple tendon adhesions is always a challenge in research on the prevention of tendon adhesion. In the present study, an M2M@PLGA/COX-siRNA delivery system is successfully constructed using the cell membranes of M2 macrophages and poly (lactic-co-glycolic acid) (PLGA) nanoparticles. Targeting properties and therapeutic effects are observed in mice or rat models of flexor digitorum longus (FDL) tendon injury combined with rotator cuff injury. The results showed that the M2M@PLGA/COX-siRNA delivery system has low toxicity and remarkable targeting properties to the injured areas. Treatment with the M2M@PLGA/COX-siRNA delivery system reduced the inflammatory reaction and significantly improved tendon adhesion in both the FDL tendon and rotator cuff tissues. These findings indicate that the M2M@PLGA delivery system can provide an effective biological strategy for preventing multiple tendon adhesions.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Engineering a cell-hydrogel-fibre composite to mimic the structure and function of the tendon synovial sheath

The repair of tendon injuries is often compromised by post-operative peritendinous adhesions. Placing a physical barrier at the interface between the tendon and the surrounding tissue could potentially solve this problem by reducing adhesion formation. At present, no such system is available for routine use in clinical practice. Here, we propose the development of a bilayer membrane combining a nanofibrous poly(ε-caprolactone) (PCL) electrospun mesh with a layer of self-assembling peptide hydrogel (SAPH) laden with type-B synoviocytes. This bilayer membrane would act as an anti-adhesion system capable of restoring tendon lubrication, while assisting with synovial sheath regeneration. The PCL mesh showed adequate mechanical properties (Young's modulus=19±4 MPa, ultimate tensile stress=9.6±1.7 MPa, failure load=0.5±0.1 N), indicating that the membrane is easy to handle and capable to withstand the frictional forces generated on the tendon's surface during movement (~0.3 N). Morphological analysis confirmed the generation of a mesh with nanosized PCL fibres and small pores (< 3 μm), which prevented fibroblast infiltration to impede extrinsic healing but still allowing diffusion of nutrients and waste. Rheological tests showed that incorporation of SAPH layer allows good lubrication properties when the membrane is articulated against porcine tendon or hypodermis, suggesting that restoration of tendon gliding is possible upon implantation. Moreover, viability and metabolic activity tests indicated that the SAPH was conducive to rabbit synoviocyte growth and proliferation over 28 days of 3D culture, sustaining cell production of specific matrix components, particularly hyaluronic acid. Synoviocyte-laden peptide hydrogel promoted a sustained endogenous production of hyaluronic acid, providing an anti-friction layer that potentially restores the tendon gliding environment.

Improved tendon healing by a combination of Tanshinone IIA and miR-29b inhibitor treatment through preventing tendon adhesion and enhancing tendon strength

Background: Despite significant advances in the materials and methods development used in surgical repair and postoperative rehabilitation, the adhesion formation remains the most common clinical problem in tendon injuries. Therefore, the development of novel therapies is necessary for targeting at preventing tendon adhesion formation and improving tendon strength. Methods: We used rat fibroblasts for in vitro experiments to determine the optimal concentration of TSA in rats, and then set up negative control group, TSA intervention group, mir-29b interference adenovirus intervention group and TSA and mir-29b interference adenovirus co-intervention group. By comparing cell proliferation and protein expression in different group, we verified the effect and mechanism of drugs on fibroblast function. At the same time, the Sprague-Dawley rat Achilles tendon model in vivo was established in this study, which was divided into sham operation group and operation group. Afterwards in the operation group, mir-29b inhibitor and placebo were injected every 3 days respectively. Then the injection inhibitor group was divided into 5 groups which mean TSA was injected into the marked area at 0, 6, 24 and 72 hours after operation for 1 week, finally all of the rats were died at 3 weeks after operation. Through the observation of general properties, histological observation of Achilles tendon injury, biomechanical test and cell and protein expression in rats' tendon cell, the effect of drugs on tendon adhesion formation was analyzed. Results: We demonstrated that the combination of miR-29b inhibitor and tanshinone IIA(TSA) could prevent tendon adhesion and also enhance tendon strength. Mechanically, the miR-29b inhibitor could activate the TGF-β/Smad3 pathway to trigger endogenous pathways and induce a high proliferation of fibroblast. Subsequently, we also found adding TSA after 6 hours of miR-29b treatment gave less cell cytotoxicity in our rat model with better outcome of less tendon adhesion and enhanced strength. Conclusion: We conclude that the use of miR-29b inhibitor at the end of the tendon break could initiate endogenous repair mechanism and subsequently use of TSA should be able to inhibit the exogenous repair mechanism. Therefore, the combination of both treatments could prevent tendon adhesion and ensure tendon strength. Our findings suggested that this approach would be a feasible approach for tendon repair.

Incidence of tenolysis and features of adhesions in the digital flexor tendons after multi-strand repair and early active motion

We report seven patients requiring tenolysis after primary or delayed primary flexor tendon repair and early active mobilization out of 148 fingers of 132 consecutive patients with Zone 1 or 2 injuries from 1993 to 2017. Three fingers had Zone 2A, two Zone 2B, and two Zone 2C injuries. Two fingers underwent tenolysis at Week 4 or 6 after repair because of suspected repair rupture. The other five fingers had tenolysis 12 weeks after repair. Adhesions were moderately dense between the flexor digitorum superficialis and profundus tendons or with the pulleys. According to the Strickland and Tang criteria, the outcomes were excellent in one finger, good in four, fair in one, and poor in one. Fingers requiring tenolysis after early active motion were 5% of the 148 fingers so treated. Indications for tenolysis were to achieve a full range of active motion in the patients rated good or improvement of range of active motion of the patients rated poor or fair. Not all of our patients with poor or fair outcomes wanted to have tenolysis. Level of evidence: IV.

Wide Awake Secondary Tendon Reconstruction

The wide awake anesthesia technique is a useful tool in secondary tendon reconstruction. With active participation of the patient, the tendon repair can be adjusted appropriately to prevent repairs that are too tight or too loose. Areas of tendon scarring or triggering can be identified and released. Other advantages of active participation include reduction of gapping, ensuring adequate strength of repair, and avoiding tendon imbalances. Last, it allows intraoperative patient education and may therefore increase patient satisfaction. This article discusses how the technique can be applied to tenolysis, 2-stage tendon reconstruction, and tendon transfer.

Local administration of Trolox, a vitamin E analog, reduced tendon adhesion in a chicken model of flexor digitorum profundus tendon injury

Background

Hand flexor tendon injuries are compromised with tendon adhesion. Tendon adhesion forms between flexor tendon and tendon sheath, reduces the range of motion of fingers, and affects their function. Oxidative stress is increased in flexor tendon after injury and might play a role in tendon adhesion formation. Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), a water-soluble analog of vitamin E, is antioxidative. Trolox reduced oxidative stress and the expression of fibrotic cytokines in the bile gut ligation animal model. Vitamin C and Trolox are strong antioxidants, but they might also have prooxidant properties. The prooxidant properties of vitamin C and Trolox are different. In this study, our aim was to determine the effect of Trolox in reducing tendon adhesion formation.

Methods

Flexor digitorum profundus tendon injury was induced in 54 Kai-Mei Chicken according to a well-established protocol. After wound closure, an injection of 50 μL saline, 10mM Trolox, or 100mM Trolox was administered into the wound area. At 2 weeks or 6 weeks after the surgery, chicken feet were harvested for gliding test, high-resolution ultrasound measurement on a fibrotic area, and histology.

Results

At Week 2 after the surgery, Trolox has no effect on the flexion angle and gliding resistance, whereas a significant improvement was observed in the flexion angle and gliding resistance in the Trolox-treated groups at Week 6. However, no dose response was observed. In the ultrasound measurement, there was no significant difference in the fibrotic mass in the Trolox-treated group as compared to the saline group at Week 2. At Week 6, fibrotic mass was significantly reduced in both Trolox-treated groups. From the histological examination, the Trolox-treated groups presented a higher cellularity at Week 2 as compared to the saline group, and reduced fibrosis and adhesion at Week 6.

Conclusion

Our results suggest that local administration of Trolox can reduce tendon adhesion, and a higher dose of Trolox did not have negative effects.

Clinical Significance

Trolox solution might be feasible to reduce tendon adhesion via intraoperative injection at the wound area during tendon repair.

Challenges Posed by Delayed Presentation of Mutilating Hand Injuries

Management of mutilating hand injury is a challenge for any hand surgeon. Delay in presentation makes management even more challenging, usually because of inadequate initial assessment, inadequate debridement leading to infection, and secondary loss of tissues from exposure and desiccation. The aim is to obtain a functional hand by radical debridement, adequate assessment of the injury, appropriately timed reconstruction, and physiotherapy and rehabilitation. The hand surgeon must pay attention to the appearance of the hand by elimination of deformities, unsightly scars and bulky flaps to help to restore confidence in the patient to face the demands of daily living.

Tanshinone IIA Prevent Tendon Adhesion in the Rat Achilles Tendon Model

Background: Tendon adhesion between the sheath and tendon surface is a common clinical problem. Orthopedist makes the improvement of repair techniques and rehabilitation to treat tendon adhesion, but it fails to cure completely. TSA was one of the major active phytochemicals because of its anti-inflammatory activity. We used tanshinone IIA (TSA) for the prevention of tendon adhesion in the rat Achilles tendon model and investigated the possible mechanisms, including microRNAs (miRNAs) and protein expression via TGF-β/Smad signaling pathway. Method: Sprague-Dawley (SD) rat Achilles tendons were half partial lacerated and sutured by a modified Kessler's technique, with TSA and normal saline for control. Macroscopic and histological evaluations were applied to examine the injured tendon six weeks after surgery. We evaluated the degree of adhesion in Gross observation and the remodeling of collagen fibers by observing microscopically and determining the amount of scar formation. The expression of microRNAs (miRNAs) was quantified by real-time PCR detection and protein expression were quantified by western blotting detection. Results: In gross evaluation of tendon adhesion, the TSA group had less adhesion appeared. No evidences of tendon rupture or local infection were observed. The content of collagen fibers in tendon tissue was decreased in TSA group compared with the control group, it indicated a significant difference from the control group, P = 0.0004. The expression of miRNAs including miR-155, miR-29b, miR21, miR-133b and let7 were detected in the repaired tendon tissue, and only miR-29b treated with TSA was observed significantly higher than control group, P <0.0001. The protein expression of TGF-β1 and p-Smad3 treated with TSA was lower than control group. Conclusions: The usage of TSA may be an efficient approach for preventing tendon adhesion.

Prognostic factors in two-stage flexor tendon reconstruction: Is it possible to predict surgical failure?

INTRODUCTION

Two-stage surgical reconstruction of the flexor tendons by the Hunter technique is the salvage option in case of old tears or a severely damaged fibro-osseous canal.

HYPOTHESIS

The identification of poor prognostic factors during the assessment of injuries at presentation could help determine indications and predict failures.

MATERIALS AND METHODS

We report a retrospective single center series of reconstruction of zone 2 of the flexor digitorum profundus of the long fingers between 2000 and 2012, in 22 patients, mean age 33 years old with a mean follow-up of 36.4 months.

RESULTS

The total active range of motion (TAM) of the rays was 110° with a mean range of motion of the PIP and DIP of 71° and 39° respectively. Sixty-three percent of patients were satisfied and 73% returned to their professional activities. A group with good and fair results was determined based on the Strickland classification (68%, 15 patients, mean TAM 126°, mean QuickDASH 22.6) and a group with poor results (32%, 7 patients, mean TAM 77°, mean QuickDASH 43.4). The factors of a poor prognosis were associated injuries to the extensor apparatus, infection (phlegmon) (P=0.023) and joint injuries (P=0.09).

DISCUSSION

There are no factors in the literature to predict a poor prognosis except for reconstruction of the flexor pollicis longus. A simplified procedure could provide better results in patients with associated injuries to the extensor apparatus, infection (phlegmon) or osteoarticular damage, in terms of the duration of physical therapy, additional surgery and overall socioeconomic cost. The results in the literature of superficialis finger reconstruction are significantly better (P<0.001).

CONCLUSION

Although the Hunter technique is still the reference procedure for the reconstruction of flexor tendons, our study identified prognostic factors of poor functional results such as infection and associated extensor apparatus damage, which should orient the surgeon towards a simplified technique such as the superficialis finger procedure.

LEVEL OF EVIDENCE

IV: retrospective study.

The effect of flexor digitorum profundus tendon shortening on jersey finger surgical repair: a cadaveric biomechanical study

Delayed diagnosis of jersey finger injuries often results in retraction of the flexor digitorum profundus tendon. Current practice recommends limiting tendon advancement to 1 cm in delayed repairs. The purpose of this study was to investigate the biomechanical consequences of tendon shortening on the force required to form a fist. The flexor digitorum profundus muscle was isolated in ten cadaveric forearms and the force required to form a fist was recorded. Simulated jersey finger injuries to the ring finger were then created and repaired. The forces required to pull the fingertips to the palm after serial tendon advancements were measured. There was a near linear increase in the force required for making a fist with shortening up to 2.5 cm. The force required to make a fist should be taken into account when considering the limit of 'safe' tendon shortening in delayed repair of jersey finger injuries.

Systemic EP4 Inhibition Increases Adhesion Formation in a Murine Model of Flexor Tendon Repair

Flexor tendon injuries are a common clinical problem, and repairs are frequently complicated by post-operative adhesions forming between the tendon and surrounding soft tissue. Prostaglandin E2 and the EP4 receptor have been implicated in this process following tendon injury; thus, we hypothesized that inhibiting EP4 after tendon injury would attenuate adhesion formation. A model of flexor tendon laceration and repair was utilized in C57BL/6J female mice to evaluate the effects of EP4 inhibition on adhesion formation and matrix deposition during flexor tendon repair. Systemic EP4 antagonist or vehicle control was given by intraperitoneal injection during the late proliferative phase of healing, and outcomes were analyzed for range of motion, biomechanics, histology, and genetic changes. Repairs treated with an EP4 antagonist demonstrated significant decreases in range of motion with increased resistance to gliding within the first three weeks after injury, suggesting greater adhesion formation. Histologic analysis of the repair site revealed a more robust granulation zone in the EP4 antagonist treated repairs, with early polarization for type III collagen by picrosirius red staining, findings consistent with functional outcomes. RT-PCR analysis demonstrated accelerated peaks in F4/80 and type III collagen (Col3a1) expression in the antagonist group, along with decreases in type I collagen (Col1a1). Mmp9 expression was significantly increased after discontinuing the antagonist, consistent with its role in mediating adhesion formation. Mmp2, which contributes to repair site remodeling, increases steadily between 10 and 28 days post-repair in the EP4 antagonist group, consistent with the increased matrix and granulation zones requiring remodeling in these repairs. These findings suggest that systemic EP4 antagonism leads to increased adhesion formation and matrix deposition during flexor tendon healing. Counter to our hypothesis that EP4 antagonism would improve the healing phenotype, these results highlight the complex role of EP4 signaling during tendon repair.

Clinical Results of Flexor Tendon Repair in Zone II Using a six Strand Double Loop Technique

The purpose of this study is to report the clinical results after repair of flexor tendon zone II injuries utilizing a 6-strand double-loop technique and early post-operative active rehabilitation. We retrospectively reviewed 22 patients involving 51 cases with zone II flexor tendon repair using a six strand double loop technique from September 1996 to December 2012. Most common mechanism of injuries was sharp lacerations (86.5 %). Tendon injuries occurred equally in manual and non-manual workers and were work-related in 33 % of the cases. The Strickland score for active range of motion (ROM) postoperatively was excellent and good in the majority of the cases (81 %). The rupture rate was 1.9 %. The six strand double loop technique for Zone II flexor tendon repair leads to good and excellent motion in the majority of patients and low re- rupture rate. It is clinically effective and allows for early postoperative active rehabilitation.

Principles of tendon reconstruction following complex trauma of the upper limb

Reconstruction of tendons following complex trauma to the upper limb presents unique clinical and research challenges. In this article, the authors review the principles guiding preoperative assessment, surgical reconstruction, and postoperative rehabilitation and management of the upper extremity. Tissue engineering approaches to address tissue shortages for tendon reconstruction are also discussed.

[Primary flexor tendons repair in zone 2]

Primary flexor tendon repair is still challenging even in the most experienced hands. With atraumatic surgery, the goal is to suture the tendon in a way that it will be strong enough to allow for tendon gliding without the risk of rupture or adhesions during the 12 weeks needed for the tendon to heal. After reviewing the zone 2 anatomy, the authors describe the state of art for flexor tendon repair along with their personal preferences. Although suture methods and postoperative rehabilitation programs are not universal, most specialized teams now use multistrand suturing techniques with at least 4 stands along with protected and controlled early active mobilization. Although the published rates of failure of the repair or postoperative adhesions with stiffness have decreased, these complications are still a concern. They will continue to pose a challenge for scientists performing research into the mechanics and biology of flexor tendon repairs, especially in zone 2.

A comparative study of the effects of growth and differentiation factor 5 on muscle-derived stem cells and bone marrow stromal cells in an in vitro tendon healing model

PURPOSE

To investigate the ability of muscle-derived stem cells (MDSCs) supplemented with growth and differentiation factor-5 (GDF-5) to improve tendon healing compared with bone marrow stromal cells (BMSCs) in an in vitro tendon culture model.

METHODS

Eighty canine flexor digitorum profundus tendons were assigned into 5 groups: repaired tendon (1) without gel patch interposition (no cell group), (2) with BMSC-seeded gel patch interposition (BMSC group), (3) with MDSC-seeded gel patch interposition (MDSC group), (4) with GDF-5-treated BMSC-seeded gel patch interposition (BMSC+GDF-5 group), and (5) with GDF-5-treated MDSC-seeded gel patch interposition (MDSC+GDF-5 group). After culturing for 2 or 4 weeks, the failure strength of the healing tendons was measured. The tendons were also evaluated histologically.

RESULTS

The failure strength of the repaired tendon in the MDSC+GDF-5 group was significantly higher than that of the non-cell and BMSC groups. The stiffness of the repaired tendons in the MDSC+GDF-5 group was significantly higher than that of the non-cell group. Histologically, the implanted cells became incorporated into the original tendon in all 4 cell-seeded groups.

CONCLUSIONS

Interposition of a multilayered GDF-5 and MDSC-seeded collagen gel patch at the repair site enhanced tendon healing compared with a similar patch using BMSC. However, this increase in vitro was relatively small. In the clinical setting, differences between MDSC and BMSC may not be substantially different, and it remains to be shown that such methods might enhance the results of an uncomplicated tendon repair clinically.

CLINICAL RELEVANCE

Muscle-derived stem cell implantation and administration of GDF-5 may improve the outcome of tendon repair.

Flexor tendon repair, rehabilitation, and reconstruction

BACKGROUND

Flexor tendon injury is a common problem that plastic surgeons are called on to treat. Despite their common nature, they present a challenge, not necessarily in the surgical treatment per se but in the ability to achieve a "normal" finger as the end result. Because of the difficulty in attaining good outcomes, much continues to be studied and written about flexor tendon injury.

METHODS

The current literature on flexor tendon repair, rehabilitation, and reconstruction is reviewed.

RESULTS

Aspects reviewed include type of anesthesia, suture material and configuration, repairs in the different flexor tendon zones, types of tendon rehabilitation, complications of flexor tendon surgery, and flexor tendon reconstruction.

CONCLUSION

This review provides an update on the current standards in the treatment of flexor tendon injury.

IFSSH Flexor Tendon Committee report 2014: from the IFSSH Flexor Tendon Committee (Chairman: Jin Bo Tang)

Hand surgeons continue to search for the best surgical flexor tendon repair and treatment of the tendon sheaths and pulleys, and they are attempting to establish postoperative regimens that fit diverse clinical needs. It is the purpose of this report to present the current views, methods, and suggestions of six senior hand surgeons from six different countries - all experienced in tendon repair and reconstruction. Although certainly there is common ground, the report presents provocative views and approaches. The report reflects an update in the views of the committee. We hope that it is helpful to surgeons and therapists in treating flexor tendon injuries.

Development of biodegradable polycaprolactone film as an internal fixation material to enhance tendon repair: an in vitro study

Background

Current tendon repair techniques do not provide sufficient tensile strength at the repair site, and thus early active motion rehabilitation after tendon repair is discouraged. To enhance the post-operative tensile strength, we proposed and tested an internal fixation technique using a polycaprolactone (PCL) biofilm. PCL was chosen for its good biocompatibility, excellent mechanical strength, and an appropriate degradation time scale.

Methods

PCL biofilms were prepared by a modified melt-molding/leaching technique, and the physical and mechanical properties and in vitro degradation rate were assessed. The pore size distribution of the biofilm and the paratenon of native tendons were observed using scanning electron microscopy. Next, we determined whether this biofilm could enhance the tensile strength of repaired tendons. We performed tensile tests on rabbit Achilles tendons that were first lacerated and then repaired: 1) using modified Kessler suture combined with running peripheral suture (‘control’ group), or 2) using biofilm to wrap the tendon and then fixation with sutures (‘biofilm’ group). The influence of different repair techniques on tendon tensile strength was evaluated by mechanical testing.

Results

The novel biofilm had supple texture and a smooth surface. The mean thickness of the biofilm was 0.25 mm. The mean porosity of the biofilm was 45.3%. The paratenon of the rabbit Achilles tendon had pores with diameters ranging from 1 to 9 μm, which were similar to the 4–12 μm diameter pores in the biofilm cross-section. The weight loss of the biofilms at 4 weeks was only 0.07%. The molecular weight of PCL biofilms did not change after immersion in phosphate buffered saline for 4 weeks. The failure loads of the biofilm were similar before (48 ± 9 N) and after immersion (47 ± 7 N, P > 0.1). The biofilm group had ~70% higher mean failure loads and 93% higher stiffness compared with the control group.

Conclusions

We proposed and tested an internal fixation technique using a PCL biofilm to enhance tendon repair. Internal fixation with the biofilm followed by standard suturing can significantly increase the tensile strength of tendon repair sites. This technique has the potential to allow active motion rehabilitation during the early post-operative period.

Allograft tendon for second-stage tendon reconstruction

Tendons are made of compact dense collagen fibers with only sparse cellularity and naturally low immunogenicity. Allogenic tendons may be preserved through deep freezing methods and retain excellent mechanical properties after revitalization. Allogenic tendons were used in 22 patients (30 tendons) for second-stage tendon reconstruction in the hand. Preliminary results indicate no observable adverse tissue reactions, and functional recovery after tendon grafting does not seem different from reconstruction using tendon autografts. This type of allogenic graft does not seem to produce serious concern as a foreign tissue in the body, at least in the short term.

Flexor tenorrhaphy using absorbable suture materials

BACKGROUND

Nonabsorbable sutures are favorable for repairing flexor tendons. However, absorbable sutures have performed favorably in an animal model.

METHODS

Two-strand sutures using the interlocking modified Kessler method with polydioxanone absorbable sutures 4-0 were used to repair completely ruptured flexor tendons in 55 fingers from 41 consecutive patients. The medical records of average 42 follow up weeks were analyzed retrospectively. The data analyzed using the chi-squared test, and Fisher's exact test was used for postoperative complications. The results were compared with those of other studies.

RESULTS

Among the index, middle, ring, and little fingers were injured in 9, 17, 16, and 13 fingers, respectively. The injury levels varied from zone 1 to 5. Of the 55 digits in our study, there were 26 (47%) isolated flexor digitorum profundus (FDP) injuries and 29 (53%) combined FDP and with flexor digitorum superficialis injuries. Pulley repair was also conducted. Concomitant injuries of blood vessels and nerves were found in 17 patients (23 fingers); nerve injuries occurred in 5 patients (10 fingers). Two patients had ruptures (3.6%), and one patient had two adhesions (3.6%). Using the original Strickland criteria, all the patients were assessed to be excellent or good. Also, fibrosis and long-term foreign body tissue reactions such as stitch granuloma were less likely occurred in our study. Compared to the Cullen's report that used nonabsorbable sutures, there was no significant difference in the rupture or adhesion rates.

CONCLUSIONS

Therefore, this study suggests that appropriate absorbable core sutures can be used safely for flexor tendon repairs.

The epidemiology of reoperation after flexor tendon repair

PURPOSE

To describe the incidence of reoperation and the demographic factors that may be associated with reoperation after flexor tendon repair.

METHODS

Using a New York statewide hospital administrative database covering an 8-year period, we examined unique patient discharges with an index procedure of flexor tendon repair for reoperation (re-repair or tenolysis). We compared the age, sex, race, and insurance type by reoperation status using standard univariate statistics and multivariate regression analysis. We performed trend analysis using the Cochran-Armitage trend test.

RESULTS

From 1998 to 2005, there were 5,229 flexor tendon repairs with a frequency of reoperation of 6%; of these, 91% were in the first year after the primary procedure. Those who underwent reoperation were significantly older than those who did not undergo reoperation. Patients with workers' compensation were 63% more likely to undergo reoperation than those with other forms of insurance. Patients who had concomitant nerve repair during the index procedure were 26% less likely to undergo reoperation. The rate of reoperation did not change during the study period.

CONCLUSIONS

These results may be useful in shaping research agendas to evaluate sociodemographic factors contributing to reoperations.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

Acute true trigger wrist following partial extensor carpi radialis brevis tendon rupture

Triggering in association with movements of the wrist or "true trigger wrist" due to the extensor tendon is rare. There are only few case reports in literature, but none were associated with the acute partial tendon rupture. We present a case of true trigger wrist originating from partial rupture of extensor carpi radialis brevis tendon (ECRB). In contrast to the other reports, the interval between an initial injury and development of triggering was short because the partial tendon rupture was bunching and forming a nodule. The triggering was attributed to the snapping of the nodule under the extensor pollicis longus tendon (EPL).

Flexor tendon tissue engineering: acellularization of human flexor tendons with preservation of biomechanical properties and biocompatibility

OBJECTIVE

Acellular human tendons are a candidate scaffold for tissue engineering flexor tendons of the hand. This study compared acellularization methods and their compatibility with allogeneic human cells.

METHOD

Human flexor tendons were pretreated with 0.1% ethylenediaminetetracetic acid (EDTA) for 4  h followed by 24  h treatments of 1% Triton X-100, 1% tri(n-butyl)phosphate, or 0.1% or 1% sodium dodecyl sulfate (SDS) in 0.1% EDTA. Outcomes were assessed histologically by hematoxylin and eosin and SYTO green fluorescent nucleic acid stains and biochemically by a QIAGEN DNeasy kit, Sircol collagen assay, and 1,9 dimethylmethylene blue glycosaminoglycan assay. Mechanical data were collected using a Materials Testing System to pull to failure tendons acellularized with 0.1% SDS. Acellularized tendons were re-seeded in a suspension of human dermal fibroblasts. Attachment of viable cells to acellularized tendon was assessed biochemically by a cell viability assay and histologically by a live/dead stain. Data are reported as mean±standard deviation.

RESULT

Compared with the DNA content of fresh tendons (551±212  ng DNA/mg tendon), only SDS treatments significantly decreased DNA content (1% SDS [202.8±37.4  ng DNA/mg dry weight tendon]; 0.1% SDS [189±104  ng DNA/mg tendon]). These findings were confirmed by histology. There was no decrease in glycosaminoglycans or collagen following acellularization with SDS. There was no difference in the ultimate tensile stress (55.3±19.2 [fresh] vs. 51.5±6.9 [0.1% SDS] MPa). Re-seeded tendons demonstrated attachment of viable cells to the tendon surface using a viability assay and histology.

CONCLUSION

Human flexor tendons were acellularized with 0.1% SDS in 0.1% EDTA for 24  h with preservation of mechanical properties. Preservation of collagen and glycoaminoglycans and re-seeding with human cells suggest that this scaffold is biocompatible. This will provide a promising scaffold for future human flexor tendon tissue engineering studies to further assess biocompatibility through cell proliferation and in vivo studies.