Clinical outcomes of zone II flexor tendon repair depending on mechanism of injury

The Outcome of the WALANT Technique in Primary Hand Flexor Tendons Repair

Introduction

Wide-awake local anesthesia and no tourniquet (WALANT) represents a revolutionary technique for hand surgeons who dismiss tourniquets and sedation. In this study, we present our experience with the WALANT technique in primary flexor tendon injuries of the hand.

Patient and methods

This prospective research was carried out on 30 patients undergoing hand primary, flexor tendon repair surgery. Flexor tendon injury zones 2, 3, 4, and 5 were included. WALANT was prepared and injected. The tendons were surgically managed by a cruciate single cross-stitched locked 4-strand technique. The pain was assessed using a visual analog scale (VAS) score. The range of motion (ROM) of affected fingers was assessed according to the Strickland evaluation system.

Results

There was a highly significant relationship between the patient's compliance with physiotherapy and obtained ROM of the affected finger with a P value <0.001. During injection of WALANT solution, 4 cases (13.3%) had no pain, 25 cases (83.3%) had mild pain (score 1-4), and 1 case (3.3%) had moderate pain (score 5-7).

Conclusion

WALANT provides an optimal bloodless and comfortable field with an opportunity to assess the strength of tendon repair, gapping or triggering and managing them intra-operatively.

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.

Short-Term and Long-Term Therapeutic Results of Deep Flexor Tendon Repair in Zone II in Patients Referred to Imam Khomeini Hospital, Ahvaz, Southern Iran

Background

Hand injury as an important concern for the surgeon and the patient requires proper and timely treatment to prevent complications such as infection and adhesions, and with a proper rehabilitation program, the patient returns to maximum function as soon as possible. We aimed to investigate the short-term and long-term treatment results of deep flexor tendon repair in in zone II.

Methods

This retrospective study was performed on 34 patients with 45 injured fingers in the zone II referred to Ahvaz Imam Khomeini Hospital, Ahvaz, Iran during 2017-2019. The results of deep flexor tendons repair in two groups, immediate and delayed primary repair were assessed.

Results

The mean age of the patients was 27.76 years. There was no significant remarkable between male and female in the incidence of complications such as infection, tendon rupture and adhesions. 29.4% (n=10) had poor outcome, 8.8% (n=3) had fair outcome, 29.4% (n=10) had good outcome and 32.4% (n=11) had excellent outcomes. 26.5% had adhesion and infection rate was 11.8%.

Conclusion

Among surgeons, there is consensus for the primary repair of tendon injury, but there was no significant difference between the results of immediate and delayed primary repair. Although physiotherapy has been suggested as an effective factor in improving hand function, its positive effect on the range of motion of the fingers has not been proven.

Flexor Tendon Repair in Zone II Augmented With an Externalized Detensioning Suture: Protected Flexor Tendon Repair

Flexor tendon repair in zone II benefits from early finger motion to prevent stiffness. This article presents a technique that serves to augment a zone II flexor tendon repair with an externalized detensioning suture that can be used following any commonly employed repair method. This simple technique enables early active motion and is suited for patients who are less likely to be compliant after surgery or when the soft-tissue injury to the finger and hand is substantial. Although this technique substantially strengthens the repair, a possible drawback is that the tendon excursion distal to the repair is limited until the externalized suture is removed, which may lead to less motion of the distal interphalangeal than what may have occurred without the detensioning suture.

Reoperation Following Zone II Flexor Tendon Repair

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Relationship between pain, nerve injury and clinical outcomes after flexor tendon injuries in zones 1-2: a retrospective cohort study

Introduction

The influence of pain and a concomitant digital nerve injury on the course of rehabilitation after flexor tendon injury remains ambiguous. The objectives of the study were to: i) analyse the evolution of pain spanning one year after a primary flexor tendon repair in zones 1-3; ii) examine the differences in pain levels in patients with and without digital nerve injury; and iii) evaluate the relationship between pain, digital nerve injury and pain medication, total active motion (TAM), DASH scores and patient satisfaction.

Methods

Data from 189 patients were retrieved from a flexor tendon registry between 2014 and 2020. Differences in pain, TAM, DASH and patient satisfaction were analysed. Multiple linear and binary logistic regression analyses were performed to determine the relationship between clinical outcomes.

Results

Pain significantly decreased in the course of rehabilitation (p < 0.001 to 0.006). No relationship could be identified between nerve injury and pain (p = 0.21-0.97). In week 6, the presence of pain and a nerve injury were significantly associated with lower TAM scores (p = 0.001). In week 13, pain during motion (p < 0.001) and the presence of a nerve injury (p = 0.036) were significantly associated with worse DASH scores. Patient satisfaction was significantly inversely correlated to pain during motion in weeks 13 and 26 (p < 0.001).

Conclusion

We found a significant relationship between pain during motion and pain medication intake, TAM, DASH scores and patient satisfaction. It is therefore advisable to closely monitor this parameter after flexor tendon injuries.

Study registration

This multi-center cohort study is registered under https://clinicaltrials.gov: NCT04312412.

Flexor Tendon Reconstruction

Chronic injury to the flexor tendon system of the hand remains a challenging problem for the hand surgeon to treat. Both single- and two-stage techniques remain important in the reconstruction of the flexor tendon deficient digit. Modern advances include the use of allograft composites that aim to reduce the time and donor-site morbidity compared with conventional autograft techniques. Regardless of technique, restoring a gliding tendon-pulley system with a functional arc of motion is the primary goal of flexor tendon reconstruction.

Isolated Flexor Digitorum Profundus Injuries in Flexor Zone II of the Hand: A Report of Five Cases

Injuries of the hand's flexor tendons carry a poor prognosis, mainly if they are in zone II (also called 'the critical zone' or 'no man's land'). The superficial tendon in this zone ends by bifurcating and attaching to the sides of the middle phalanx, exposing the deep tendon that attaches to the distal phalanx. Thus, trauma to this zone may result in a complete cut to the deep tendon while the superficial one remains intact. The lacerated tendon, in turn, would be retracted proximally to the palm making it difficult to be found during wound exploration. The complex anatomy of the hand, particularly that of the flexor zones, may contribute to the misdiagnosis of a tendon injury. We report five cases of an isolated cut of the flexor digitorum profundus (FDP) tendon after traumatic injury to the flexor zone II of the hand. The mechanism of injury of each case is reported together with a clinical approach that guides ED physicians toward diagnosing flexor tendon injuries in hand. In cut wounds involving the flexor zone II of the hand, it should be not surprising to find that the deep tendon (FDP) is completely lacerated without an injury to the superficial one (FDS). Therefore, we conclude that a systematic examination approach for traumatic hand injuries is essential to ensure the proper assessment. Understanding the mechanism of injury, performing a systemic examination approach, and having basic anatomical knowledge of flexor tendons of the hand are essential to identifying tendon injuries, anticipating complications, and providing adequate healthcare.

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

III.

Zone II Flexor Pollicis Longus Repair: Thumb Flexion and Complications

Background: The aim of flexor pollicis longus (FPL) repair is to create a construct that is strong enough to withstand forces encountered during rehabilitation and to achieve an optimal active range of motion. The aim of this study was to: (1) assess factors influencing active thumb interphalangeal (IP) joint flexion; and (2) assess the factors associated with reoperation. Methods: Retrospectively, 104 patients with primary repair of a Zone II FPL laceration from 2000 to 2016 were identified. A medical chart review was performed to collect patient-, injury-, and surgery characteristics as well as the degree of postoperative active IP-flexion and occurrence of reoperation. Bivariate analyses were performed to identify factors influencing active IP-flexion and factors associated with reoperation. Results: The reoperation rate was 17% (n = 18) at a median of 3.4 months (range: 2.3-4.4). Indications for reoperation mainly included adhesion formation (n = 10, 56%) and re-rupture (n = 5, 28%). The median range of active IP-flexion was 30° (interquartile range [IQR]: 20-45) at a median of 12.4 weeks (IQR: 8.1-16.7). Solitary injury to the thumb (β = 17.9, P = .022) and the use of epitendinous suture (β = 10.0, P = .031) were associated with increased active IP-joint flexion. No factors were statistically associated with reoperation. Conclusions: About 1 in 5 patients undergo reoperation following primary repair of a Zone II FPL laceration, mostly within 6 months of initial surgery. The use of epitendinous suture is associated with greater active IP-flexion. Patients with multiple digits injured accompanying a Zone II FPL laceration have inferior IP-joint motion.

Outcome measurement in adult flexor tendon injury: A systematic review

BACKGROUND

Defining the optimal, evidence-based management of flexor tendon injury remains challenging. Lack of consensus on which measures to use to assess the outcome of interventions is a key issue, especially with regard to patient-reported outcome measures (PROMs). This systematic review defines the landscape of outcome measurement in studies on interventions for flexor tendon injuries to guide future research.

METHODS

A PRISMA-compliant systematic review was conducted using bespoke search strategies applied to MEDLINE, EMBASE, PsycINFO, CENTRAL, CINAHL and AMED. A protocol was developed and registered prospectively (CRD42020186780). We identified all studies describing adult patients undergoing interventions for acute hand flexor tendon injuries.

RESULTS

Of the 4844 studies, 114 studies met the final inclusion criteria for evaluating the outcomes of 8127 participants with 9071 injured digits. Studies included 24 randomised controlled trials, 19 cohort studies and 61 case series. Nine different PROMs were used in 24 studies (22%): three site-specific PROMs, one generic quality-of-life measure and four visual analogue scales. Clinician-reported outcome measures were used in 103 studies (96%), such as the range of motion reported in 102 studies (94%). Adverse outcomes were reported in 96 studies (89%), with the most frequently reported adverse outcomes being tendon rupture and infection. Re-operation was reported in 21 studies (19%). The most frequently reported health economic outcome measure was the length of work absence, reported in ten studies (9%).

CONCLUSIONS

There is variability in the use of outcome measures used to study interventions for flexor tendon injuries. An independent systematic review of the psychometric properties of the identified outcome measures and a specific multi-stakeholder consensus process may support optimal choice and standardisation for future studies.

Secondary Procedures following Flexor Tendon Reconstruction

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Understand the indications and management options for secondary flexor tendon reconstruction, including tenolysis, tendon grafting, and tendon transfers. 2. Understand the reconstructive options for pulley reconstruction. 3. Understand the options for management of isolated flexor digitorum profundus injuries.

SUMMARY

Despite current advances in flexor tendon repair, complications can still occur following surgery. This article presents the spectrum of treatment options for secondary flexor tendon reconstruction ranging from tenolysis to one- and two-stage tendon grafting, and tendon transfers. In addition, an overview of pulley reconstruction and the treatment of isolated flexor digitorum profundus injuries are discussed. A management algorithm for secondary flexor tendon reconstruction is provided.

Use of a relative motion flexion orthosis for postoperative management of zone I/II flexor digitorum profundus repair: A retrospective consecutive case series

STUDY DESIGN

A retrospective, single-center, consecutive case series.

INTRODUCTION

In concept, a relative motion flexion (RMF) orthosis will induce a "quadriga effect" on a given flexor digitorum profundus (FDP) tendon, limiting its excursion and force of flexion while still permitting a wide range of finger motion. This effect can be exploited in the rehabilitation of zone I and II FDP repairs.

PURPOSE OF THE STUDY

To describe the use of RMF orthoses to manage zone I and II FDP 4-strand repairs.

METHODS

Medical record review of 10 consecutive zone I and II FDP tendon repairs managed with RMF orthosis for 8 to 10 weeks in combination with a static dorsal blocking or wrist orthosis for the initial 3 weeks.

RESULTS

Indications included sharp lacerations (n = 6), ragged lacerations (n = 2), staged flexor tendon reconstruction (n = 1), and type IV avulsion (n = 1). In 8 of the 10 cases that completed follow-up, the mean arc of proximal interphalangeal/distal interphalangeal active motion were as follows: sharp, 0° to 106°/0° to 75°; ragged, 0° to 90°/0° to 25°; reconstruction, 0° to 90°/10° to 45°; and avulsion, 0° to 95°/0° to 20°. Grip performance available for 6 of 10 cases was 62% to 108% of the dominant hand. There were no tendon ruptures, secondary surgeries, or proximal interphalangeal joint contractures.

CONCLUSION

Based on this small series, the RMF approach appears to be safe and effective. It can lead to similar mobility and functional recovery as other early active motion protocols, with certain practical advantages and without major complications. Further investigation with larger, multicenter, prospective, longitudinal cohorts and/or randomized clinical trials is necessary.

Beyond the Core Suture: A New Approach to Tendon Repair

Despite significant improvements in zone II flexor tendon repair over the last 2 decades, function-limiting complications persist. This article describes 2 novel repair techniques utilizing flexor digitorum superficialis (FDS) autografts to buttress the flexor digitorum profundus (FDP) repair site without the use of core sutures. The hypothesis being that the reclaimed FDS tendon autograft will redistribute tensile forces away from the FDP repair site, increasing overall strength and resistance to gapping in Zone II flexor tendon injuries compared with the current clinical techniques.

Methods

Two novel FDP repair methods utilizing portions of FDS have been described: (1) asymmetric repair (AR), and (2) circumferential repair. Ultimate tensile strength and cyclical testing were used to compare novel techniques to current clinical standard repairs: 2-strand (2-St), 4-strand (4-St), and 6-strand (6-St) methods. All repairs were performed in cadaveric sheep tendons (n = 10/group), by a single surgeon.

Results

AR and circumferential repair techniques demonstrated comparable ultimate tensile strength to 6-St repairs, with all 3 of these techniques able to tolerate significantly stronger loads than the 2-St and 4-St repairs (P < 0.0001). Cyclical testing demonstrated that AR and circumferential repair were able to withstand a significantly higher total cumulative force (P < 0.001 and P = 0.0064, respectively) than the 6-St, while only AR tolerated a significantly greater force to 2-mm gap formation (P = 0.042) than the 6-St repair.

Conclusion

Incorporating FDS as an autologous graft for FDP repair provides at least a comparable ultimate tensile strength and a significantly greater cumulative force to failure and 2-mm gap formation than a traditional 6-St repair.

Effect of Time to Hand Therapy following Zone II Flexor Tendon Repair

This population-based study aimed to define how time to hand therapy following isolated zone II flexor tendon repairs impacts complications and secondary procedures.

METHODS

Insurance claims from the Truven MarketScan Databases were used to evaluate outcomes after isolated zone II flexor tendon repairs between January 2009 and October 2015. Cohorts differing in time to hand therapy were compared to evaluate the impact on complications, reoperation, and number of therapy sessions. Secondary outcomes analyzed how the number of therapy sessions affected rates of reoperation.

RESULTS

Hand therapy was identified in 82% of patients (N = 2867) following tendon reconstruction. Therapy initiation occurred within 1 week, 1-4 weeks, and after 4 weeks in 56%, 35%, and 9% of patients, respectively. Univariate analysis showed no difference in non-tendinous complications (27%, 30%, 29%; P = 0.29) or tendon rupture rates (13%, 13%, 10%; P = 0.42) within 90 days between cohorts. Multivariable analysis showed no difference in rates of tenolysis (6.3%, 6%, 4.4%; P > 0.01). In the early initiation cohort, >23 hand therapy sessions were associated with the highest rates of tenolysis (19%).

CONCLUSIONS

Despite being a common fear of hand surgeons, early initiation of hand therapy was not associated with increased tendon rupture rates. Although delayed therapy is a concern for tendon scarring, it did not confer a higher risk of tenolysis. Complication rates do not appear to correlate with timing of hand therapy. Therefore, hand surgeons should promote early mobility following isolated flexor tendon injuries given the known functional outcome benefits.

Functional and Disability Assessment Among Hispanics With Zone 2 Flexor Tendon Injuries: Comparative Study Between Flexor Digitorum Superficialis Repair and Flexor Digitorum Superficialis Excision

Flexor tendon lacerations in zone II have been reported to be the most complicated of all tendon injuries. Currently, there is no consensus on treatment in surgical management for patients with flexor tendon laceration of flexor digitorum profundus and flexor digitorum superficialis (FDS). The aim of this study was to evaluate whether the repair of FDS tendons provided superior functional outcomes compared with FDS excision in Hispanic patients.

Functional outcomes after flexor tendon repair of the hand

Objectives

This study aims to evaluate the hand function after flexor tendon repair (FTR) and to investigate factors associated with functional outcomes.

Patients and methods

Between January 2013 and September 2015, a total of 126 patients (84 males, 42 females; mean age 31 years; range, 15 to 62 years) who underwent FTR due to flexor tendon injuries (FTIs) were included. The hand function was assessed using the Jebsen Hand Function Test (JHFT) and Quick Disabilities of the Arm, Shoulder and Hand (Quick DASH) at three and six months following FTR.

Results

Of the patients, 94 (75%) and 72 (56%) completed the three-month and six-month assessment visits, respectively. A total of 65 patients (51.1%) had both three and six-month follow-up data. The patients regained a fair amount of power grip strength and more than half of their pinch grip strength compared to the unaffected hand. The results of assessment of hand function at activity and participation levels (JHFT and Quick DASH) showed slightly higher levels of disability. Of 41 patients who were employed prior to injury, 29 (71%) returned to work at six months after surgery. Zone IV injury and language barrier were associated with poor functional outcomes at six months.

Conclusion

Our study results showed that the JHFT and Quick DASH scores of the patients were less than the established norms, although functional outcomes improved over time. Based on these results, we suggest that the presence of zone IV FTI and language barrier are associated with poor functional outcomes.

Flexor Subzone II A-D Range of Motion Progression during Healing on a No-Splint, No-Tenodesis Protection, Immediate Full Composite Extension Regimen

Background: The objective was to study the hypotheses that an advanced zone II flexor tendon rehabilitation protocol would avoid rupture, achieve a high range of excursion, and minimize interphalangeal contracture during both the early phases and at the conclusion of healing. We also proposed the null hypothesis of no difference between any two of the zone II subdivisions. Methods: Fifty-one consecutive adult patients with zone II flexor tendon repairs of a single finger were retrospectively evaluated on an active contraction rehabilitation protocol with no splint, no tenodesis protection, and immediate full composite extension. There were 38 males and 13 females with a mean age of 39 years (range 18-69) involving 15 index, 7 long, 6 ring, and 23 small fingers. Repairs were located in flexor subzone IIA for 8 fingers; subzone IIB, 14; subzone IIC, 19; and subzone IID, 10. Differences in outcome between any two subzones were compared by T-test with p < 0.05. Results: Mean active arcs of motion in degrees at 3 weeks post repair were PIP 1-93; DIP 0-44; and total active motion (TAM) 221. At 6 weeks PIP 2-98; DIP 1-51; and TAM 236. At 10-12 weeks PIP 1-101; DIP 1-56; and TAM 246. Final TAM by flexor subzone IIA was 243; IIB, 251; IIC, 246; and IID, 246. There were no significant differences between any two subzones. Mean final DASH score was 5. There were no ruptures. Conclusions: The results support the hypotheses. Outcomes of the therapy protocol demonstrated the lack of interphalangeal joint flexion contractures, high range of total active motion achieved early and sustained, and no ruptures. No differences were identified between and two of the flexor subzones.

Utility of early active motion for flexor tendon repair with concomitant injuries: A multivariate analysis

INTRODUCTION

Flexor tendon injury often occurs with concomitant injuries such as fracture, vascular injury, and extensor tendon injury. These injuries are repaired independently, without a comprehensive strategy. We aimed to identify the effect of concomitant injuries and treatment choice on the outcome of flexor tendon repair.

PATIENTS AND METHODS

We evaluated 118 fingers of 102 adult patients with zone 1-3 flexor digitorum profundus (FDP) tendon injuries who underwent primary surgery at our hospital between April 2009 and December 2017. The 2-strand pull-out, 4-strand Tsuge, 6-strand Lim & Tsai, and 8-strand cross-locked cruciate suturing techniques were used. We performed multivariate analyses, with the active range of motion (AROM) of the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints as dependent variables, and age, existence of concomitant injuries, and their treatment as independent variables.

RESULTS

The average AROM of the PIP + DIP joints was 130° at the last follow-up, and 'excellent' or 'good' function was obtained in 74 (63%) of 118 fingers by using the Strickland criteria. Old age, concomitant diaphyseal fractures, and specific methods of osteosynthesis, such as pinning, flexor digitorum superficialis injury, and immobilisation for 3 weeks, significantly worsened the results. However, wiring for osteosynthesis and early active motion protocol improved postoperative functional outcome. Although the outcome did not differ among the suture techniques, the 4-strand Tsuge procedure was performed for the two surgically confirmed ruptures of repair that occurred in our series.

DISCUSSION

We clarified the superiority of early mobilisation protocols with rigid osteosynthesis procedure, other than pinning. To minimise tendon adhesion or joint stiffness, surgeons should repair the tendon and fractured bone appropriately, to ensure early mobilisation without serious complications.

Biological Augmentation of Flexor Tendon Repair: A Challenging Cellular Landscape

Advances in surgical technique and rehabilitation have transformed zone II flexor tendon injuries from an inoperable no-man's land to a standard surgical procedure. Despite these advances, many patients develop substantial range of motion-limiting adhesions after primary flexor tendon repair. These suboptimal outcomes may benefit from biologic augmentation or intervention during the flexor tendon healing process. However, there is no consensus biological approach to promote satisfactory flexor tendon healing; we propose that insufficient understanding of the complex cellular milieu in the healing tendon has hindered the development of successful therapies. This article reviews recent advances in our understanding of the cellular components of flexor tendon healing and adhesion formation, including resident tendon cells, synovial sheath, macrophages, and bone marrow-derived cells. In addition, it examines molecular approaches that have been used in translational animal models to improve flexor tendon healing and gliding function, with a specific focus on progress made using murine models of healing. This information highlights the importance of understanding and potentially exploiting the heterogeneity of the cellular environment during flexor tendon healing, to define rational therapeutic approaches to improve healing outcomes.

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.

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.

Regulatory effects of introduction of an exogenous FGF2 gene on other growth factor genes in a healing tendon

In this study of a tendon injury model, we investigated how injection of a vector incorporating one growth factor gene changes expression levels of multiple growth factor genes in the healing process. The flexor tendon of chicken toes was completely cut and repaired surgically. The tendons in the experimental arm were injected with an adeno-associated virus-2 vector incorporating basic fibroblast growth-factor gene, whereas the tendons in the control arm were not injected or injected with sham vectors. Using real-time polymerase chain reaction, we found that, within the tendon healing period, a set of growth factor genes-transforming growth factor-β1, vascular endothelial growth factor, and connective tissue growth factor-were significantly up-regulated. Expression of the platelet-derived growth factor-B gene was not changed, and the insulin-like growth factor was down-regulated. A tendon marker gene, scleraxis, was significantly up-regulated in the period. Our study revealed an intriguing finding that introduction of one growth factor gene in the healing tendon modulated expression of multiple growth factor genes. We believe this study may have significant implications in determining the approach of gene therapy, and the findings substantiate that gene therapy using a single growth factor could affect multiple growth factors.

Evidence-based medicine: Flexor tendon repair

LEARNING OBJECTIVES

After studying this article, the participant should be able to: (1) Describe and apply the current evidence-based treatment of acute flexor tendon injuries. (2) Compare and contrast the current postoperative therapy regimens following repair of flexor tendons. (3) Apply an evidence-based decision-making process for suture techniques of flexor tendon injuries.

SUMMARY

Flexor tendon repair remains a challenge for hand surgeons to reliably obtain excellent results. Surgical decisions should rely on the surgeon's experience, outcome studies, and direct evidence. This review is a compilation of the evidence from the literature on optimizing outcomes for flexor tendon repair.

A systematic review of 2-strand versus multistrand core suture techniques and functional outcome after digital flexor tendon repair

PURPOSE

To determine published evidence to evaluate the hypothesis that multistrand techniques result in a poorer outcome than 2-strand techniques for digital flexor tendon repairs.

METHODS

A systematic review was undertaken to compare outcomes and rupture rates between 2-strand and multistrand core sutures in digital flexor zones 2 to 5. Outcome was measured by the American Society for Surgery of the Hand criteria, original or modified Strickland criteria, or Buck-Gramcko criteria.

RESULTS

A total of 1,878 patients (2,585 digits; 3,749 tendons) were included from the selected studies. Thirty-three studies reported 2-strand repairs and 15 reported multistrand repairs. Of the total tendon injuries, 59% were flexor digitorum profundus, 38% were flexor digitorum superficialis, and 2% were flexor pollicis longus. The pooled rupture rate was 3.9 per 100 digits. No significant difference was detected between 2-strand and multistrand repairs for outcomes by all measures or rupture rate.

CONCLUSIONS

Because of the wide variation in reporting of outcomes and study design on which this analysis was based, we cannot definitively confirm our hypothesis. We present the standards for outcomes as well as rupture rate for digital flexor tendon repair.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Decellularized human tendon-bone grafts for composite flexor tendon reconstruction: a cadaveric model of initial mechanical properties

PURPOSE

After complex hand trauma, restoration of tendon strength is challenging. Tendon insertion tears typically heal as fibrous scars after surgical reconstruction and create a weak point at the tendon-bone interface. In addition, major tendon loss may overwhelm the amount of available autograft for reconstruction. An off-the-shelf product may help address these challenges. We hypothesized that decellularized human flexor digitorum profundus and distal phalanx tendon-bone composite grafts were a feasible option for flexor tendon reconstruction after complex hand trauma. By replacing the entire injured composite segment, the need for tendon repair within the tendon sheath, reconstruction of the tendon-bone interface, and use of limited autograft could be eliminated.

METHODS

Paired human cadaver forearms were dissected to obtain the flexor digitorum profundus tendon with an attached block of distal phalanx. Tendon-bone grafts were pair-matched and divided into 2 groups: decellularized grafts (n = 12) and untreated (control) grafts (n = 11). Grafts in the decellularized group were subjected to physiochemical decellularization. Pair-matched tendon-bone grafts (decellularized and untreated) were placed back into the flexor tendon sheath and secured distally using a tie-over button and proximally by weaving the graft into the flexor digitorum superficialis tendon in the distal forearm. The ultimate load, location of failure, and excursion were determined.

RESULTS

Decellularized tendon-bone composite grafts demonstrated no significant difference in ultimate failure load or stiffness compared with untreated grafts. Both groups eventually failed in varied locations along the repair. The most common site of failure in both groups was the tie-over button. The decellularized group failed at the tendon-bone insertion in 3 specimens (25%) compared with none in the untreated group. Both groups demonstrated an average tendon excursion of approximately 82 mm before failure.

CONCLUSIONS

Decellularization of human flexor tendon-distal phalanx tendon-bone constructs did not compromise initial strength despite chemical and mechanical decellularization in a cadaveric model. At the time of repair, decellularized flexor tendon-bone grafts can exceed the strength and excursion needed for hand therapy immediately after reconstruction.

CLINICAL RELEVANCE

These tendon-bone grafts may become an option for complex hand reconstruction at or near tendon-bone insertions and throughout the tendon sheath. Further work is required to assess the role of reseeding in an in vivo model.

Outcomes and evaluation of flexor tendon repair

This article reviews recent reports of outcomes of flexor tendon repair and discusses the problems associated with such surgeries. Reports of no repair rupture in individual case series have emerged recently. Their results move toward the clinical goal of primary repair without repair rupture. The Strickland method remains the most common to record the outcomes. Outcomes should be provided by subzones of the tendon injuries, and the level of expertise of the surgeons expertise should be reported to allow comparisons of the results.