The aetiology of acute rupture of flexor tendon repairs in zones 1 and 2 of the fingers during early mobilization

Mental and behavioural disorders increase the risk of tendon rupture after flexor tendon repair in zone I and II

Introduction

The effect of mental and behavioural disorders (MBD) on the risk of tendon ruptures after flexor tendon repair is not well understood. This study aimed to analyse the association between MBD and tendon rupture after flexor tendon repair in zones I and II.

Methods

Data from the Swedish National Registry for Hand Surgery (HAKIR) on patients with a complete flexor tendon repair at our department between 2012 and 2019 were followed for a minimum of 2 years to assess the rate of rupture. Independent variables were collected from HAKIR and clinical records: prevalence MBD based on ICD-10 codes F0-F99, age, sex, injured tendon, number of injured fingers, day to surgery, core suture, digital nerve injury, smoking, injury mechanism, and rehabilitation method. Multiple logistic regression was used to assess the association between variables.

Results

A cohort of 593 patients with 49 ruptures (8.2%) was identified. Potential causes of rupture were non-adherence behaviour in 16 (33%), accidents in seven (14%), infections in six (12%), and no clear cause in 20 (41%) patients. Patients with MBD had an association to rupture (OR 3.6), 17.7% ruptures compared to 7.2% in patients with no diagnosed disorders. Patients >50 years of age had a higher risk compared to patients <25 years (OR 4.3), 15% compared to 3.9%' respectively. Men had a higher risk compared to women (OR 2.9), 10% compared to 4.3%' respectively.

Conclusion

We identified an association between the prevalence of mental and behavioural disorders and rupture after flexor tendon repair.

A Lightweight Dynamic Hand Orthosis With Sequential Joint Flexion Movement for Postoperative Rehabilitation of Flexor Tendon Repair Surgery

During the postoperative hand rehabilitation period, it is recommended that the repaired flexor tendons be continuously glided with sufficient tendon excursion and carefully managed protection to prevent adhesion with adjacent tissues. Thus, finger joints should be passively mobilized through a wide range of motion (ROM) with physiotherapy. During passive mobilization, sequential flexion of the metacarpophalangeal (MCP) joint followed by the proximal interphalangeal (PIP) joint is recommended for maximizing tendon excursion. This paper presents a lightweight device for postoperative flexor tendon rehabilitation that uses a single motor to achieve sequential joint flexion movement. The device consists of an orthosis, a cable, and a single motor. The degree of spatial stiffness and cable path of the orthosis were designed to apply a flexion moment to the MCP joint prior to the PIP joint. The device was tested on both healthy individuals and a patient who had undergone flexor tendon repair surgery, and both flexion and extension movement could be achieved with a wide ROM and sequential joint flexion movement using a single motor.

Flexor Tendon Repair: Avoidance and Management of Complications

The proper technique for flexor tendon repair has been well established through numerous bench science and clinical studies. However, less is known about strategies to avoid and manage postoperative complications. This article discusses the common complications after flexor tendon repair, such as repair site rupture and adhesion formation. This article also addresses strategies to prevent and manage these complications. The foundation for preventing many of these complications is ensuring a strong repair without gapping at time zero, which will enable the accrual of tensile strength through early initiation of motion.

Tenolysis and Salvage Procedures

Complications in flexor tendon repair are common and include tendon rupture, adhesion formation, and joint contracture. Risk factors include preexisting conditions, gross contamination, concurrent fracture, early unplanned loading of the repaired tendon, premature cessation of splinting, and aggressive early active range of motion protocols with insufficient repair strength. Rupture of a repaired tendon should be followed by early operative exploration, debridement, and revision with a four-core strand suture and nonbraided epitendinous suture. Wide-awake flexor tenolysis should be considered when adhesion formation results in the plateaued range of motion, and passive motion exceeds active motion. Two-staged reconstruction is recommended when injury results in excessive scaring, joint contracture, or an incompetent pulley apparatus.

Patients' experiences of flexor tendon rehabilitation in relation to adherence: a qualitative study

PURPOSE

To explore patients' experiences of early active motion flexor tendon rehabilitation in relation to adherence to restrictions and outcome of rehabilitation.

METHOD

Seventeen patients with a flexor tendon injury in one or several fingers participated in qualitative interviews performed between 74 and 111 days after surgery. Data were analysed using directed content analysis with the Health Belief Model (HBM) as a theoretical framework.

RESULTS

Perceived severity of hand function and susceptibility to loss of hand function affected the participants' behaviour. A higher perceived threat increased motivation to exercise and be cautious in activities. During rehabilitation, the perceived benefits or efficacy of doing exercise and following restrictions were compared to the cost of doing so, leading to adherence or non-adherence behaviour. Perceived self-efficacy was affected by previous knowledge and varied through the rehabilitation period. External factors and interaction with therapists influenced the perception of the severity of the injury and the cost and benefits of adhering to rehabilitation.

CONCLUSION

Patient's perception of the injury, the effectiveness of exercises, context and social support to manage daily life affected adherence to restriction, motivation and commitment to rehabilitation. The HBM as a theoretical framework can be beneficial for understanding factors that influence patients' adherence.Implications for RehabilitationInformation regarding the injury and consequences for the patient should be presented at different time points and in different ways, tailored to the patient.It' is important to aid patients to perceive the small gradual improvements in hand function to create motivation to adhere to exercise.Strategies to reduce the cost of adherence in terms of managing everyday life should be addressed by individually based strategies.Instructions regarding exercise and restrictions should be less complex and consider the patient's individual needs.

Relative motion flexion following zone I-III flexor tendon repair: Concepts, evidence and practice

STUDY DESIGN

Narrative review and case series.

INTRODUCTION

The relative motion approach has been applied to rehabilitation following flexor tendon repair. Positioning the affected finger(s) in relatively more metacarpophalangeal joint flexion is hypothesized to reduce the tension through the repaired flexor digitorum profundus by the quadriga effect. It is also hypothesized that altered patterns of co-contraction and co-inhibition may further reduce flexor digitorum profundus tension, and confer protection to flexor digitorum superficialis.

METHODS

We reviewed the existing literature to explore the rationale for using relative motion flexion orthoses as an early active mobilization strategy for patients after zone I-III flexor tendon repairs. We used this approach within our own clinic for the rehabilitation of a series of patients presenting with zone I-II flexor tendon repair. We collected routine clinical and patient reported outcome data.

RESULTS

We report published outcomes of the clinical use of relative motion flexion orthoses with early active motion, implemented as the primary rehabilitation approach after zone I-III flexor digitorum repairs. We also report novel outcome data from 18 patients.

DISCUSSION

We discuss our own experience of using relative motion flexion as a rehabilitation strategy following flexor tendon repair. We explore orthosis fabrication, rehabilitation exercises and functional hand use.

CONCLUSIONS

There is currently limited evidence informing use of relative motion flexion orthoses following flexor tendon repair. We highlight key areas for future research and describe a current pragmatic randomized controlled trial.

Medium-term clinical outcomes of Zone 2B/2C finger flexor tendon repairs: influence of management of flexor digitorum superficialis

III.

Risk factors for reoperation after flexor tendon repair: a registry study

The aim of this study was to identify risk factors for reoperations after Zones 1 and 2 flexor tendon repairs. A multiple logistic regression model was used to identify risk factors from data collected via the Swedish national health care registry for hand surgery (HAKIR). The studied potential risk factors were age and gender, socio-economics and surgical techniques. Included were 1372 patients with injuries to 1585 fingers and follow-up of at least 12 months (median 37 IQR 27-56). Tendon ruptures occurred in 80 fingers and tenolysis was required in 76 fingers. Variables that affected the risk of rupture were age >25 years (p < 0.001), flexor pollicis longus tendon injuries (p < 0.001) and being male (p = 0.004). Injury to both finger flexors had an effect on both rupture (p = 0.005) and tenolysis (p < 0.001). Understanding the risk factors may provide important guidance both to surgeons and therapists when treating patients with flexor tendon injuries.Level of evidence: III.

Practice Patterns in Operative Flexor Tendon Laceration Repair: A 15-Year Analysis of Continuous Certification Data from the American Board of Plastic Surgery

The American Board of Plastic Surgery has been collecting practice data on operative repair of flexor tendon lacerations since 2006, as part of its Continuous Certification program.

Flexor tendon injuries: Repair & Rehabilitation

Flexor tendon injuries are common and occur mostly by penetrating trauma. Suspected flexor tendon injuries require a thorough clinical assessment and often are not isolated injuries. A detailed understanding of flexor tendon anatomy and spatial relationships is essential, especially when repairing multi-tendon injuries. Principles of flexor tendon repair include a strong suture construct, minimising gap formation between tendon ends, preserving tendon blood supply and providing a smooth repair interface. Moreover, adequate exposure of the zone of injury using full-thickness skin flaps and preservation of neurovascular and pulley structures is essential. In this article an overview of contemporary management strategies is presented. Today's hand surgeons and therapists can choose from a variety of treatment options when managing these important and potentially life-changing injuries.

Comparative Sensitivity and Specificity of Static and Dynamic High-Resolution Ultrasound in Diagnosis of Small Gaps in Repaired Flexor Tendons: A Cadaveric Study

PURPOSE

To compare the sensitivity and specificity of high-resolution static and dynamic ultrasound (US) for diagnosing intact repairs and small, clinically relevant gaps (≥4 mm) in repaired flexor digitorum profundus tendons within zone 2 and, secondarily, to evaluate the effect of suture artifact from 3 commonly used suture types.

METHODS

Eighty-eight fresh-frozen cadaveric digits (thumbs excluded) were randomized to either an intact repair (0-mm gap) or repairs using a locked 4-strand suture repair with either 4-0 Prolene, Ethibond, or FiberWire and gaps of 2, 4, or 6 mm and no suture in which 2-, 4-, or 6-mm gaps were created without a suture crossing the repair site. Gap widths were estimated by a blinded musculoskeletal ultrasonographer in static and dynamic modes.

RESULTS

Both static and dynamic modalities tended to overestimate actual gap sizes. For the suture gaps, both modalities had poor sensitivity (29% static; 42% dynamic) for accurately diagnosing a clinically intact repair (<4 mm), but better specificity (83% static; 75% dynamic) for diagnosing a clinically failed repair (≥4-mm gap). Although suture presence decreased the sensitivity of gap width measurement for both modalities, no differences were seen between suture types.

CONCLUSIONS

Static and dynamic US have poor sensitivity for diagnosing clinically intact repairs (gaps < 4 mm) because they typically overestimate gap size. The ability to diagnose failed repairs (gap ≥ 4 mm), based on greater specificity, is much better, but still suboptimal.

CLINICAL RELEVANCE

Based on a receiver operating characteristic analysis cutoff of 5 mm, if a gap of 5 mm or larger is identified with US when evaluating a zone 2 flexor digitorum profundus tendon repair, a failed repair is likely in about 80% of cases. A gap measurement of less than 5 mm may miss a high percentage of repairs that are clinically failed.

Homing of Adipose-Derived Stem Cells to a Tendon-Derived Hydrogel: A Potential Mechanism for Improved Tendon-Bone Interface and Tendon Healing

PURPOSE

Tendons are difficult to heal owing to their hypocellularity and hypovascularity. Our laboratory has developed a tendon-derived hydrogel (tHG) that significantly improves tendon healing in an animal model. We hypothesized that a potential mechanism for improved healing with tHG is through the attraction of systemic stem cells.

METHODS

Homing of systemic adipose-derived stem cells (ADSCs) to tendon injuries was assessed with acute and chronic injury models. Injury sites were treated with saline or tHG, and animals given a tail vein injection (TVI) of labeled ADSCs 1 week after treatment. One week following TVI, rats were harvested for histology. To further evaluate a potential difference in homing to tHG, a subcutaneous injection (SQI) model was used. Rats were treated with an SQI of saline, silicone, ADSCs in media, tHG, tHG + fibroblasts (FBs), or tHG + ADSCs on day 0. One week after SQI, rats underwent TVI with labeled ADSCs. Samples were harvested 2 or 3 weeks after SQI for analysis. Flow cytometry confirmed homing in the SQI model.

RESULTS

Systemically delivered ADSCs homed to both acute tendon and chronic tendon-bone interface (TBI) injury sites. Despite their presence at the injury site, there was no difference in the number of macrophages, amount of cell proliferation, or angiogenesis 1 week after stem cell delivery. In an SQI model, ADSCs homed to tHG. There was no difference in the number of ADSCs homing to tHG alone versus tHG + ADSCs. However, there was an increase in the number of living cells, general immune cells, and T-cells present at tHG + ADSC versus tHG alone.

CONCLUSIONS

The ADSCs home to tendon injury sites and tHG. We believe the attraction of additional systemic ADSCs is one mechanism for improved tendon and TBI healing with tHG.

CLINICAL RELEVANCE

Treatment of tendon and TBI injuries with tHG can augment healing via homing of systemic stem cells.

A smartphone application to facilitate adherence to home-based exercise after flexor tendon repair: A randomised controlled trial

OBJECTIVE

Evaluate the effect of a smartphone application on exercise adherence, range of motion and self-efficacy compared to standard rehabilitation after repair of the flexor digitorum profundus tendon.

DESIGN

Prospective multi-centre randomised controlled trial.

SETTING

Four hand surgery departments in Sweden.

SUBJECTS

A total of 101 patients (35 women) (mean age 37.5 ± 12.8) were randomised to control (n = 49) or intervention group (n = 52).

INTERVENTION

A smartphone application to facilitate rehabilitation.

MAIN OUTCOME MEASURES

Adherence assessed with the Sport Injury Rehabilitation Adherence Scale at two and six weeks (primary outcome). Secondary outcomes were self-reported adherence in three domains assessed at two and six weeks, self-efficacy assessed with Athlete Injury Self-Efficacy Questionnaire at baseline, two and six weeks. Range of motion and perceived satisfaction with rehabilitation and information were assessed at 12 weeks.

RESULTS

Twenty-five patients were lost to follow-up. There was no significant between group difference in Sport Injury Rehabilitation Adherence Scale at two or six weeks, mean scores (confidence interval, CI 95%) 12.5 (CI 11.8-13.3), 11.8 (CI 11.0-12.8) for the intervention group, and 13.3 (CI 12.6-14.0), 12.8 (CI 12.0-13.7) for the control group. Self-reported adherence for exercise frequency at six weeks was significantly better for the intervention group, 93.2 (CI 86.9-99.5) compared to the controls 82.9 (CI 76.9-88.8) (P = 0.02). There were no differences in range of motion, self-efficacy or satisfaction.

CONCLUSION

The smartphone application used in this study did not improve adherence, self-efficacy or range of motion compared to standard rehabilitation for flexor tendon injuries. Further research regarding smartphone applications is needed.

LEVEL OF EVIDENCE

I. Randomised controlled trial.

Clinical Outcomes of Zone 2 Flexor Tendon Repairs Using the Modified Lim/Tsai Technique

BACKGROUND

The single looped suture modified Lim/Tsai technique is widely used for flexor tendon repairs. It has been shown to possess better biomechanical properties and require less repair time per tendon as compared to the double looped suture original Lim/Tsai technique. However, there is no clinical data on the modified technique.

METHODS

The retrospective study included zone 2 flexor tendon repairs made using the modified Lim/Tsai technique from January 2008 to December 2014. Clinical outcome was assessed using the revised Strickland and Glogovac criteria, which categorises repairs based on the total active motion of the repaired digit.

RESULTS

Sixty-two patients with 74 digits were included. The overall mean total active motion was 122°. The overall satisfactory outcome of the modified Lim/Tsai technique was 81.1%. The rupture rate of the modified Lim/Tsai technique was 2.7%. Using multivariate linear regression model, we found that outcomes were negatively influenced by subzone 2C and crush/saw injuries, but not by concomitant neurovascular injuries or post-operative follow-up duration.

CONCLUSIONS

Based on this retrospective study of patients with zone 2 flexor tendon injuries, the clinical outcomes of modified and original Lim/Tsai techniques are comparable. As such, there is no clinical evidence favouring one over the other.

Comparison of the strength of two multi-strand tendon repair configurations in a chicken model

We sought to investigate the strength of two multi-strand tendon repair configurations in a chicken model. Fifty-six chicken flexor tendons were repaired with one to two different four-strand configurations: 1) a four-strand repair consisting of a two-strand core modified Kessler suture with a circle loop repair and 2) a four-strand core Kessler suture repair with three separate peripheral suture points. The strength of the repaired tendons were measured 2, 3 and 4 weeks after the surgical repair and were analyzed statistically. The strength of the two repair methods was not statistically different 2 weeks after surgery. The tendons repaired with the four-strand core Kessler suture repair and three separate peripheral suture points were significantly stronger than those repaired with a two-strand core modified Kessler suture and a circle loop repair at 3 weeks (P = 0.033) and 4 weeks (P = 0.039). The four-strand repair with three separate peripheral suture points had greater strength than a two-strand repair with one circle loop suture based on an in vivo chicken flexor tendon model.

Isolation and Characterization of Multipotent Turkey Tendon-Derived Stem Cells

Tendon injuries are among the most common and severe hand injuries with a high demand for functional recovery. Stem cells have been identified and isolated from different species and a variety of tissues for the sake of regenerative medicine. Recently, turkey has been suggested as a potential new large animal model for flexor tendon-related research. However, turkey tissue-specific stem cells have not been investigated. Here, we presented the isolation and verification of tendon-derived stem cells (TDSCs) from 6- to 8-month-old heritage-breed turkey. TDSCs were isolated from turkey flexor tendon by plating nucleated cells at the determined optimal density. Approximately 4% of the nucleated cells demonstrated clonogenicity, high proliferation rate, and trilineage differentiation potential after induction culturing. These cells expressed surface antigens CD90, CD105, and CD44, but did not express CD45. There was a high level of gene expression of tenogenic markers in TDSCs, including mohawk, collagen type I, tenascin C, and elastin. Turkey TDSCs also expressed transcription factors PouV, Nanog, and Sox2, which are critically involved in the regulation of stemness. The successful isolation of tendon-derived stem cells from turkey was beneficial for future studies in tendon tissue engineering and would help in the development of new treatment for tendon diseases using this novel animal model.

Effects of PDGF-BB delivery from heparinized collagen sutures on the healing of lacerated chicken flexor tendon in vivo

Flexor tendon lacerations are traditionally repaired by using non-absorbable monofilament sutures. Recent investigations have explored to improve the healing process by growth factor delivery from the sutures. However, it is difficult to conjugate growth factors to nylon or other synthetic sutures. This study explores the performance of a novel electrochemically aligned collagen suture in a flexor tendon repair model with and without platelet derived growth factor following complete tendon laceration in vivo. Collagen suture was fabricated via electrochemical alignment process. Heparin was covalently bound to electrochemically aligned collagen sutures (ELAS) to facilitate affinity bound delivery of platelet-derived growth factor-BB (PDGF-BB). Complete laceration of the flexor digitorum profundus in the third digit of the foot was performed in 36 skeletally mature White Leghorn chickens. The left foot was used as the positive control. Animals were randomly divided into three groups: control specimens treated with standard nylon suture (n=12), specimens repaired with heparinated ELAS suture without PDGF-BB (n=12) and specimens repaired with heparinated ELAS suture with affinity bound PDGF-BB (n=12). Specimens were harvested at either 4weeks or 12weeks following tendon repair. Differences between groups were evaluated by the degree of gross tendon excursion, failure load/stress, stiffness/modulus, absorbed energy at failure, elongation/strain at failure. Quantitative histological scoring was performed to assess cellularity and vascularity. Closed flexion angle measurements demonstrated no significant differences in tendon excursion between the study groups at 4 or 12weeks. Biomechanical testing showed that the group treated with PDGF-BB bound heparinated ELAS suture had significantly higher stiffness and failure load (p<0.05) at 12-weeks relative to both heparinated ELAS suture and nylon suture. Similarly, the group treated with PDGF-BB bound suture had significantly higher ultimate tensile strength and Young's modulus (p<0.05) at 12-weeks relative to both ELAS suture and nylon suture. Compared to nylon controls, heparinized ELAS with PDGF-BB improved biomechanics and vascularity during tendon healing by 12-weeks following primary repair. The ability of ELAS to deliver PDGF-BB to the lacerated area of tendon presents investigators with a functional bioinductive platform to improve repair outcomes following flexor tendon repair.

STATEMENT OF SIGNIFICANCE

A high strength aligned collagen suture was fabricated via linear electrocompaction and heparinized for prolonged delivery of PDFG-BB. When it was used to suture a complete lacerated flexor tendon in a chicken model controlled release of the PDGF-BB improved the strength of treated tendon after 12 weeks compared to tendon sutured with commercial nylon suture. Furthermore, Collagen suture with affinity bound PDGF-BB enhanced the vascularization and remodeling of lacerated tendon when it compare to synthetic nylon suture. Overall, electrocompacted collagen sutures holds potential to improve repair outcome in flexor tendon surgeries by improving repair strength and stiffness, vascularity, and remodeling via sustained delivery of the PDGF-BB. The bioinductive collagen suture introduces a platform for sustained delivery of other growth factors for a wide-array of applications.

The effect of adding active flexion to modified Kleinert regime on outcomes for zone 1 to 3 flexor tendon repairs. A prospective randomized trial

In a prospective randomized study, we studied whether adding active flexion to a modified Kleinert regime changed outcomes of flexor tendon repairs in zone 1, 2 and 3 in 73 fingers (53 patients). Evaluation included active range of finger motion, grip and pinch strengths. Twelve months after surgery, the increase in range of active finger motion after adding active flexion was insignificant compared with that with the modified Kleinert regime. According to the Strickland criteria, 20 out of 29 fingers had excellent or good recovery after adding active flexion, as did 28 out of 34 fingers with the modified Kleinert regime; we could not detect significant improvement of the good and excellent rate. At 6 months, the pinch strength was significantly higher with the addition of active flexion. We failed to find that adding active finger flexion to the modified Kleinert regime improves the overall long-term results of repairs in zone 1 to 3, though recovery appeared faster, and the good and excellent recovery of zone 2 repairs was 17% greater with the active flexion protocol.

LEVEL OF EVIDENCE

I.

Can Occupational Therapists be Hand Therapists?

Occupational therapists working in the field of hand therapy tend to follow a reductionist biomedical approach in their practice. This emphasis means that there is the potential to lose the occupational focus in interventions with this client group. The International Classification of Functioning, Disability and Health (World Health Organisation 2001) could be used as a framework to examine the consequences of hand injuries. By taking all four conceptual domains into account when treating this client group, it may be possible not only to examine, for example, range of movement and tendon glide but also to start looking at the occupational impact on people's activity performance and social participation following hand impairment, as well as to explore the variations of the occupational impact that these injuries have on people's lives.

A Phenomenological Investigation Of The Experience Of Patients During A Rehabilitation Programme Following A Flexor Tendon Injury To Their Hand

Following a traumatic hand injury, people experience a significant disruption to their lives. This qualitative study attempts to describe the lived experience of five people coping with the consequences of an extrinsic flexor tendon injury to their hands. Individual open-ended interviews were undertaken and a phenomenological analysis was used. The findings highlighted several themes, four of which were common to each participant:

i) minimising the impact of the injury;

ii) struggling and coping;

iii) trying to elicit help from others, and

iv) feelings of dependency.

Implications for the provision of hand therapy services to this client group, suggested by this research, are the need to identify people on whom patients will be dependent and to include them in treatment planning; the need to monitor patients’ mood states; the need for hand therapists to be more wide ranging when identifying and negotiating strategies for managing their rehabilitation time and to take a broader view of the rehabilitation process and not to focus exclusively upon exercise and splinting guidelines.

Compliance, Adherence and Concordance: A Review of Engaging Patients in their Treatment

Problems of non-attendance in hand therapy clinics are frequently recorded and linked to poor outcomes in treatment. This paper reviews the therapy and medical literature on compliance, adherence and concordance, and explores ways of gaining the closer involvement and cooperation of patients in their treatment. It suggests that while client-centred approaches and education are important aspects of gaining users’ participation, patients need active encouragement and real opportunities to become involved in health care. Hand therapists need to explore ways in which to negotiate and tailor care to individual client needs.

The effect of tendon stem/progenitor cell (TSC) sheet on the early tendon healing in a rat Achilles tendon injury model

Tissue-engineering approaches have a great potential to improve the treatment of tendon injuries that affect millions of people. The present study tested the hypothesis that introduction of a tendon derived stem/progenitor cell (TSC) sheet accelerates tendon healing and tendon regeneration in a rat model. TSC sheets were produced on temperature-responsive culture dishes. Then, they were grafted on unwounded Achilles tendons and at sites of a 3mm of Achilles tendon defect. At 2 and 4weeks after implantation tendons were examined by histology, immunohistochemistry, transmission electron microscopy (TEM) and mechanical testing. The results showed that the implanted TSC sheet remained stably attached on the tendon surface at 4 weeks after implantation. Moreover, in the tendon defect model, tendon defect area where TSC sheet was implanted was well regenerated and had better organized collagen fibers with elongated spindle shaped cells, compared to relatively disorganized collagen fibers and round shaped cells in the control group. TEM observations revealed longitudinally aligned collagen fibers and thick collagen fibrils in the TSC sheet implanted group. Finally, at 4weeks mechanical property of the TSC sheet implanted tendon had better ultimate load than the control. In conclusion, this study demonstrates the feasibility of implanting TSC sheets on tendons in vivo. Introduction of the cell sheets into a tendon defect significantly improved histological properties and collagen content at both 2 and 4 weeks after implantation, indicating that TSC sheets may effectively promote tendon remodeling in the early stages of tendon healing.

STATEMENT OF SIGNIFICANCE

Tendon injury is a highly prevalent clinical problem that debilitates millions of people worldwide in both occupational and athletic settings. It also costs billions of healthcare dollars in treatment every year. In this study, we showed the feasibility of using tendon derived stem cell sheet to deliver biologically active tenogenic-constructs and promote tendon regeneration. This work has the potential to impact the orthopaedic surgery and sports medicine fields in the treatment of tendon injury.

Differential Splintage for Flexor Tendon Rehabilitation: An Experimental Study of its Effect on Finger Flexion Strength

We conducted laboratory tests to investigate the possibility of partly de-powering flexor digitorum profundus with a view of reducing flexion force during active flexor tendon rehabilitation.

We constructed a splint and applied tapes to the proximal segments of fingers to test the hypothesis that holding three fingers more extended than the other finger would reduce the flexion strength of the more flexed finger. The splint allowed the metacarpophalangeal joint of the more flexed finger to be held in three positions of increasing flexion (15°, 30°, and 45°) compared to the remaining three fingers. We have called this ‘differential splintage’.

Healthy volunteers were tested for maximum active flexion strength at the different flexion angles. ‘Differential splintage’ of up to 45° resulted in mean decreased flexion strength of 28% in the index finger and 35% to 38% in the middle, ring and little fingers.

The results suggest that “differential splintage” of a finger after flexor tendon repair may be useful in reducing tension across the repair during a program of active tendon rehabilitation and we feel that it has potential to reduce the incidence of repair rupture before healing is complete.

Early Active Mobilization of Primary Repairs of the Flexor Pollicis Longus Tendon with Two Kessler Two-Strand Core Sutures and a Strengthened Circumferential Suture

This study reports our treatment of divided flexor pollicis longus (FPL) tendons by primary repair from 1999 to 2002. Forty-eight FPL repairs were performed using two Kessler two-strand repairs with a cross-linked Silfverskiöld circumferential suture. All were rehabilitated by early active mobilization. Excellent or good results were observed in 73/77% of cases (White/Buck–Gramcko assessments, respectively). No patients (0%) ruptured their repair as a result of early active mobilization. Two patients (4%) developed post-operative infections with wound and tendon dehiscence. This combination of repairs addresses the problem of rupture of FPL during early mobilization which we experienced in previous studies. Its problems and alternatives are discussed.

The Results of Immediate Re-Repair of Zone 1 and 2 Primary Flexor Tendon Repairs which Rupture

This study reports the outcome of immediate re-repair of primary flexor tendon repairs in zones 1 and 2 of the fingers which had ruptured. Between June 1989 and May 2003, a total of 62 fingers in 61 patients presented with ruptured flexor tendon repairs within 48 hours from rupture. Immediate re-repair and rehabilitation was carried out in 44 fingers (71%) in 43 (70%) patients. Thirty-six patients completed the 8-week therapy programme after re-repair in 37 fingers. Nine (24%) had excellent, 10 (27%) good, 5 (14%) fair and 13 (35%) had poor results when assessed by the original Strickland method. Five fingers in five patients ruptured the re-repair. Poor results and second ruptures were particularly common after re-repair of ruptured tendon repairs in the little finger. In the light of these findings, a policy for dealing with ruptured primary flexor tendon repairs in the fingers is suggested.

Epidemiology of Flexor Tendon Injuries of the Hand in a Northern Finnish Population

Background:

Flexor tendon injuries cause significant morbidity in working-age population. The epidemiology of these injuries in adult population is not well known. The aim of this study was to describe the epidemiology of flexor tendon injuries in a Northern Finnish population.

Material and Methods:

Data on flexor tendon injuries, from 2004 to 2010, were retrieved from patient records from four hospitals, which offer surgical repair of the flexor tendon injuries in a well-defined area in Northern Finland. The incidence of flexor tendon injury as well as the gender-specific incidence rates was calculated. Mechanism of injury, concomitant nerve injuries, and re-operations were also recorded.

Results:

The incidence rate of flexor tendon injury was 7.0/100,000 person-years. The incidence was higher in men and inversely related to age. The most common finger to be affected was the fifth digit. In 37% of injuries also digital nerve was affected. The most common finger to have simultaneous digital nerve injury was the thumb.

Conclusion:

Flexor tendon laceration is a relatively rare injury. It predominantly affects working-aged young males and frequently includes a nerve injury, which requires microsurgical skills from the surgeon performing the repair. This study describes epidemiology of flexor tendon injuries and therefore helps planning the surgical and rehabilitation services needed to address this entity.

Basic FGF or VEGF gene therapy corrects insufficiency in the intrinsic healing capacity of tendons

Tendon injury during limb motion is common. Damaged tendons heal poorly and frequently undergo unpredictable ruptures or impaired motion due to insufficient innate healing capacity. By basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF) gene therapy via adeno-associated viral type-2 (AAV2) vector to produce supernormal amount of bFGF or VEGF intrinsically in the tendon, we effectively corrected the insufficiency of the tendon healing capacity. This therapeutic approach (1) resulted in substantial amelioration of the low growth factor activity with significant increases in bFGF or VEGF from weeks 4 to 6 in the treated tendons (p < 0.05 or p < 0.01), (2) significantly promoted production of type I collagen and other extracellular molecules (p < 0.01) and accelerated cellular proliferation, and (3) significantly increased tendon strength by 68–91% from week 2 after AAV2-bFGF treatment and by 82–210% from week 3 after AAV2-VEGF compared with that of the controls (p < 0.05 or p < 0.01). Moreover, the transgene expression dissipated after healing was complete. These findings show that the gene transfers provide an optimistic solution to the insufficiencies of the intrinsic healing capacity of the tendon and offers an effective therapeutic possibility for patients with tendon disunion.

The Effect of 1-Ethyl-3-(3-Dimethylaminopropyl) Carbodiimide Suture Coating on Tendon Repair Strength and Cell Viability in a Canine Model

PURPOSE

To determine if impregnating a suture with a cross-linking agent, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), improved suture pull-out strength and cell viability.

METHODS

Canine flexor digitorum profundus tendons were cut in canine zone D, and a single suture loop was placed in each end, with sutures soaked in either saline or an EDC solution with a concentration of 1%, 10%, or 50%. Suture pull-out strength, stiffness, and elongation to failure was determined by pulling the loop until failure. Cytotoxicity of the EDC treatment was evaluated by suspending treated sutures over cultured tenocytes.

RESULTS

Mechanical properties for the EDC-treated side were improved over controls when treated with the 10% and 50% EDC solutions. The ratio of dead to live cells was significantly increased at all distances from the suture for the 50% EDC-treated group.

CONCLUSIONS

Suture treated with a 10% EDC solution provided the best combination of mechanical reinforcement and limited toxicity.

CLINICAL RELEVANCE

Sutures so treated may improve the ability of a tendon repair to sustain early mobilization.

Surgical adhesive BioGlue™ does not benefit tendon repair strength: an ex vivo study

Surgical adhesives are useful supplements in surgery, but their benefit in tendon repair is uncertain. The purpose of this study was to evaluate the effect of BioGlue™ on strength of flexor tendon repair. A total of 60 porcine flexor tendons were divided into three groups. In group one, a conventional core and peripheral suture repair was used. In group two, a core suture and BioGlue™ were used. In group three, a conventional core and peripheral suture repair and BioGlue™ were used. We performed static and cyclic axial load testing and measured diameter of the repair site. We found that BioGlue™ did not improve the tensile strength when added to a core and peripheral suture and that there was an increase in bulk at the repair site. We conclude that BioGlue™ application cannot replace a peripheral suture as tensile strength significantly decreases without a peripheral suture, and it does not benefit a tendon already repaired with a core and peripheral suture.

LEVEL OF EVIDENCE

n/a.

Management of complications of flexor tendon injuries

Innovations in operative techniques, biomaterials, and rehabilitation protocols have improved outcomes after treatment of flexor tendon injuries. However, despite these advances, treatment of flexor tendon injuries remains challenging. The purpose of this review is to highlight the complications of flexor tendon injuries and review the management of these complications.

Flexor digitorum superficialis repair outside the A2 pulley after zone II laceration: gliding and bowstringing

PURPOSE

To evaluate the changes in maximum flexion angle, gliding coefficient, and bowstringing after a combined repair of both flexor tendons with the flexor digitorum superficialis (FDS) rerouted outside the A2 pulley in cadaveric hands.

METHODS

We performed 4 different repairs on cadaveric hands, with each repair tested on 9 unique digits. In total, 12 cadaveric hands and 36 digits were used. The thumb and little finger were removed from each hand and excluded from testing. Group 1 was sham surgery. Group 2 combined flexor digitorum profundus (FDP) and FDS laceration and repair with both slips of the FDS repaired inside the A2 pulley. Group 3 was FDP repair with one slip of the FDS repaired inside A2 and the other slip left unrepaired. Group 4 was FDP repair with both slips of the FDS rerouted and repaired outside the A2 pulley. Maximum flexion angle, gliding coefficient, and bowstringing were measured in simulated active digital motion for each group.

RESULTS

Rerouting and repairing the FDS outside the A2 pulley (group 4) significantly lowered gliding coefficient compared with repairs with both slips inside A2, with values similar to sham surgery. We observed no significant differences in maximum flexion angle among the 4 groups. Increased bowstringing was observed with both slips of the FDS repaired and rerouted outside the A2 pulley.

CONCLUSIONS

In this cadaveric model, repair of both slips of the FDS outside the A2 pulley improved the gliding coefficient relative to repair within the A2 pulley, which suggests decreased resistance to finger flexion. Repair of the FDS outside the A2 pulley led to a slight increase in bowstringing of the FDS tendon.

CLINICAL RELEVANCE

We describe a technique for managing combined laceration of the FDP and FDS tendons that improves gliding function and merits consideration.

Re-repair of ruptured primary flexor tendon repairs in Zones I and II of the fingers in children

The aetiology, management, and results of acute rupture of primary flexor tendon repairs in Zones I and II of the fingers in children have not been previously investigated. The author reports on a personal series of 10 children treated over a period of 13 years. The aetiology is different when compared with adults: children less than 5 years of age usually rupture their primary repairs whilst the hand is completely immobilized in a cast; whereas teenagers usually rupture their tendons when falling down while playing. In the current series, direct re-repair was performed without lengthening at the musculo-tendinous junction, and no free tendon grafts were used. The results were worse than other paediatric series of primary flexor tendon repairs. Using the Strickland-Glogovac criteria, there was only one excellent outcome, the remaining nine being either a good (n = 5) or fair (n = 4) outcome.

Improving results of flexor tendon repair and rehabilitation

BACKGROUND

The global time and effort attributed to improving outcomes in the management of flexor tendon injury are large, but the degree of advancement made over the past 50 years is relatively small. This review examines the current perceived wisdom in this field and aims to explore the limitations to the authors' understanding of the tendon healing process, examining how this may be a factor that has contributed to the authors' modest progress in the field.

METHODS

The authors critically evaluate the sum of laboratory and clinical literature on the topic of zone II flexor tendon management that has guided their practice and provide evidence to support their methods.

RESULTS

The review highlights some of the key developments over the years and assesses their influence on changing current practice. It also highlights recent innovations, which have the potential to influence flexor tendon outcomes by altering the surgical approach, techniques, and rehabilitation regimens. Future innovations in the field will also be discussed to examine their potential in expanding the development in the management of flexor tendon injury.

CONCLUSIONS

A better understanding of flexor tendon biology will allow progress in developing new therapies for flexor tendon injuries; however, there are as yet few real breakthroughs that will dramatically change current practice.

Flexor tendon injury, repair and rehabilitation

Injuries to the flexor tendons remain among the most difficult problems in hand surgery. Historically, lacerations to the intrasynovial portion of the flexor tendons were thought to be unsuitable for primary repair. Despite continuing advances in our knowledge of flexor tendon biology, repair, and rehabilitation, good results following primary repair of flexor tendons remain challenging to achieve.

A new modified Tsuge suture for flexor tendon repairs: the biomechanical analysis and clinical application

Purpose

This study is to develop a new suturing technique for flexor tendon repair by modifying the extant Tsuge repair techniques and to use biomechanical analysis to compare the new method with four established repair techniques and evaluate its clinical efficacy in the repair of 47 flexor tendons in 22 patients.

Methods

The biomechanical analysis relied on 50 flexor digitorum profundus tendons harvested from fresh cadavers. The tendons were randomly divided into five groups, transected, and repaired by use of a 1. double-loop suture, 2. double modified locking Kessler, 3. four-strand Savage, 4. modified six-strand Savage, and 5. the new technique. The tensile force and breaking force of all repaired tendons were measured by static loading trials. For clinical application, 22 patients with acute flexor tendon injuries were treated with the new modified Tsuge suture and follow-up for more than 12 months.

Results

While differences in the tensile force and breaking force in the modified Tsuge sutures and modified six-strand Savage sutures were not statistically significant, static loading trials showed the tensile force, in the form of a 2-mm gap formation, and the breaking force of the new modified Tsuge sutures were, statistically, both higher than the ones characteristic of double-loop sutures, double modified locking Kessler, and four-strand Savage sutures. After 12 months, restored functions were observed in all the patients during the postoperative 12 months. Total active motion (TAM) score demonstrated that more than 90% fingers were estimated as excellent or good.

Conclusion

The new modified Tsuge sutures described here have evident higher tensile and breaking forces compared to other four-strand core suture techniques, suggesting, in turn, that this new technique is a good alternative for flexor tendon repairs in clinical applications.

[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.

Update on Zone II Flexor Tendon Injuries

Flexor tendon repair in zone II is particularly challenging because tendon gliding must be restored within a tight fibro-osseous sheath while minimizing the formation of adhesions in surrounding tissues. Meticulous surgical technique using a multistrand core suture and a peripheral suture is needed to produce a tendon that is strong enough to withstand early mobilization. Mechanical strength increases with the number of strands crossing the repair, regardless of the core suture configuration. Early mobilization after flexor tendon repair enhances the strength of the repair and decreases the risk of adhesions and joint stiffness. Satisfactory results have been achieved with either early passive or early active motion rehabilitation protocols; therefore, the choice of postoperative rehabilitation program is at the discretion of the surgeon. Factors such as repair integrity, concurrent injuries, and anticipated patient compliance should be considered in the decision-making process.

Thermographic and histological analysis of rabbit different tenorrhaphies techniques (4 and 6 strands) after early active mobilization

Introduction This research is based on the results of the surgeries of tenorraphy, which have been improved due to the association between strong and not voluminous sutures and physiotherapic protocols, which preconize the early active motion to the postoperative period. Objective To evaluate the healing process in vivo in different types of tenorraphies. Methods Thirty-six rabbits that underwent early active motion after tenorraphy. The sample was constituted of 3 groups of 12, in accordance with the 3 different types of suture (Brasil, Indiana and Tsai). Results On the 15th and 30th days after the surgery, thermographic and histological analyses revealed similar results that all groups showed similar behaviors in the same time of surgical repair, just differentiating between the periods. On the 30th day analysis were observed that collagen fibers being more exuberant thickening, thus being able to offer higher tensile strength to the tendon. Conclusion That suggests early active motion may be increased gradually to around the 30th day taking this as clinical relevance.

Primary flexor tendon repair in zones 1 and 2: early passive mobilization versus controlled active motion

PURPOSE

To compare early passive mobilization (EPM) with controlled active motion (CAM) after flexor tendon surgery in zones 1 and 2.

METHODS

We performed a retrospective analysis of collected data of all patients receiving primary flexor tendon repair in zones 1 and 2 from 2006 to 2011, during which time 228 patients were treated, and 191 patients with 231 injured digits were eligible for study. Exclusion criteria were replantation, finger revascularization, age younger than 16 years, rehabilitation by means other than EPM or CAM, and missing information regarding postoperative rehabilitation. This left 132 patients with 159 injured fingers for analysis. The primary endpoint was the comparison of total active motion (TAM) values 4 and 12 weeks after surgery between the EPM and the CAM protocols. The analysis of TAM measurements under the rehabilitation protocols was conducted using t-tests and further linear modeling. We defined rupture rate and the assessment of adhesion/infection as secondary endpoints.

RESULTS

There was a statistically significant difference between the TAM values of the EPM and the CAM protocols 4 weeks after surgery. At 12 weeks, however, there was no significant difference between the 2 protocols. Older age and injuries with finger fractures were associated with lower TAM values. Rupture rates were 5% (CAM) and 7% (EPM), which were not statistically different.

CONCLUSIONS

This study showed a favorable effect of CAM protocol on TAM 4 weeks after surgery. The percent rupture rate was slightly lower in the patients with CAM than in the patients with EPM regime. Further studies are required to confirm our results and to investigate whether faster recovery of TAM is associated with shorter time out of work.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

The Effect of Pulley Reconstruction on Maximum Flexion, Bowstringing, and Gliding Coefficient in the Setting of Zone II Repair of FDS and FDP: a Cadaveric Investigation

PURPOSE

The purpose of this experiment was to determine the effect of A2 pulley reconstruction on gliding coefficient (GC), bowstringing, and proximal interphalangeal (PIP) joint maximum flexion angle after zone II repair of flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) lacerations.

METHODS

Fresh frozen cadaver forearms were mounted, and the wrist and MCP joints fixed. FDS and FDP tendons were dissected free, and sequential loads were applied while digital images were captured. The dissected digit with intact native A2 pulley, FDS, and FDP tendons was used as the control (group 1). Zone II lacerations followed by four-stranded repair of FDP plus epitendinous suture and repair of FDS were then performed, and the data recorded (group 2). A2 pulley excision and reconstruction with a loop of palmaris longus autograft was then completed and the specimens sequentially loaded and photographed (group 3). Using the digital images, GC, bowstringing, and maximum flexion angle were calculated.

RESULTS

No difference in maximum flexion angle was observed across the three testing conditions. Zone II laceration and subsequent FDS and FDP tendon repair significantly increased the GC for group 2 specimens; however, pulley reconstruction alleviated some of this increase for group 3. Bowstringing was significantly greater after pulley reconstruction, with a mean increase of 1.9 mm at maximum flexion for group 3 specimens relative to group 1 controls.

DISCUSSION

Strong flexor tendon repairs are needed to prevent gap formation and subsequent triggering; however, the increased bulk from these large repairs can itself produce deleterious triggering, as well as tendon abrasion. Pulley reconstruction, in the setting FDP and FDS repair (group 3), significantly reduced the GC relative to tendon repair alone (group 2). While bowstringing was significantly greater after pulley reconstruction (group 3), it averaged only 1.9 mm over group 1 specimens and did not compromise maximum flexion angle compared to the uninjured controls (group 1) or the isolated tendon repair digits (group 2).

Treatment of unfavourable results of flexor tendon surgery: Ruptured repairs, tethered repairs and pulley incompetence

As primary repair of divided flexor tendons becomes more common, secondary tendon surgery becomes largely that of the complications of primary repair, namely ruptured and adherent repairs. These occur with an incidence of each in most reported series world-wide of around 5%, with these problems having changed little in the last two decades, despite strengthening our suture repairs. Where the primary referral service is less well-developed, and as a more occasional occurrence where primary treatment is the routine, the surgeon faces different problems. Patients arrive at a hand unit variable, but longer, times after the primary insult, having had no, or bad, previous treatment. Sometimes the situation is the same, viz. an extended finger with no active flexion, but now no longer amenable to primary repair. Frequently, it is much more complex as a result of injuries to the other tissues of the digit and, also, as a result of the unaided healing process within the digit in the presence of an inactive flexor system. We present our experience in dealing with ruptured repairs, tethered repairs and pulley incompetence.

The search for the ideal tendon repair in zone 2: strand number, anchor points and suture thickness

This review article examines the mechanical factors involved in tendon repair by sutures. The repair strength, repair stiffness and gap resistance can be increased by increasing the number of core strands and anchor points, by increased anchor point efficiency and the use of peripheral sutures, and by using thicker sutures. In the future, laboratory tests could be standardized to a specific animal model and to a defined cyclic motion programme. Clinical studies support the use of multi-strand core and peripheral sutures, but two-strand core sutures are not adequate to ensure consistently good clinical results. Training surgeons in complex tendon repair techniques is essential.

Primary flexor tendon surgery: the search for a perfect result

Repair of the divided flexor tendon to achieve normal, or near normal, function is an unsolved problem, with each result still uncertain. The authors believe the way forward in primary flexor tendon surgery clinically is by use of strengthened but simpler sutures, appropriate venting of the pulley system, and maintaining early rehabilitation. However, there needs also be consideration of patient factors and other aspects. Research needs to continue more widely, in both the laboratory and the clinical environment, to find ways of better modifying adhesions after surgical repair of the tendon.

Avoidance of unfavourable results following primary flexor tendon surgery

This review describes the biological problems faced by those managing primary flexor tendon injuries and explains why these problems still thwart attempts to achieve normal, or near normal, function after this injury, despite a century of surgical effort. It considers the historical background of the early 20(th) century attempts to improve the results and analyses the clinical usefulness of more recent research into tendon core and circumferential suture modification, including the authors' work in this field, and changes in post-operative mobilisation over the last 50 years. More recent manipulation of the sheath to improve results and the future possibility of manipulation of adhesions are discussed. It also discusses other factors, e.g., the patient, the experience of the surgeon, the use of therapists, the timing of repair, complex injuries, injuries in zones other than zone 2, which can have a bearing on the results and considers how these can be modified to avoid an unfavourable outcome.

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.

Does loading velocity affect failure strength after tendon repair?

Tensile testing of repaired tendons has been used to assess the efficacy of repair techniques. However, individuals flex and extend fingers at rates higher than those typically used for testing. This study characterized the effect of loading rate on the failure strength of repaired canine flexor tendons. Thirty-six canine flexor digitorum profundus tendons were lacerated, repaired, and tested at three displacement rates: 0.33 mm/s; 84 mm/s; and 590 mm/s. Peak force and stiffness of the repairs were evaluated. Peak force was significantly greater (p<0.05) for tendons distracted at 590 mm/s than at 0.33 mm/s. Crosshead stiffness was significantly greater for tendons distracted at 590 mm/s than at either 84 mm/s or 0.33 mm/s. The predominant failure mode was core suture knot untying. Distracting tendons at slow loading rates provides a conservative assessment of tendon repair strength. Additionally, an estimate of the failure load of this repair for different clinical events has been identified.

Modern tendon repair techniques

Digital tendon repair is one of the most common issues in hand surgery and also one of the most vexing. A repair must withstand the forces imparted on it during early motion. Common clinical scenarios that challenge the hand surgeon are flexor tendon injuries in zone II, zone I, and extensor tendons. Repair of tendons that have flat morphology present a particular challenge to achieving a strong repair while maintaining the native tendon shape. This article evaluates modern tendon repair techniques. Early clinical experience using such methods have shown clinical success of improved motion and no known ruptures.