The application of force to the healing tendon

The passive biomechanics of the thumb carpometacarpal joint: An in vitro study

The thumb carpometacarpal (CMC) joint facilitates multidirectional motion of the thumb and affords prehensile power and precision. Traditional methods of quantifying thumb CMC kinematics have been largely limited to range-of-motion (ROM) measurements in 4 orthogonal primary directions (flexion, extension, abduction, adduction) due to difficulties in capturing multidirectional thumb motion. However, important functional motions (e.g., opposition) consist of combinations of these primary directions, as well as coupled rotations (internal and external rotation) and translations. Our goal was to present a method of quantifying the multidirectional in vitro biomechanics of the thumb CMC joint in 6 degrees-of-freedom. A robotic musculoskeletal simulation system was used to manipulate CMC joints of 10 healthy specimens according to specimen-specific joint coordinate systems calculated from computed tomography bone models. To determine ROM and stiffness (K), the first metacarpal (MC1) was rotated with respect to the trapezium (TPM) to a terminal torque of 1 Nm in the four primary directions and in 20 combinations of these primary directions. ROM and K were also determined in internal and external rotation. We found multidirectional ROM was greatest and K least in directions oblique to the primary directions. We also found external rotation coupling with adduction-flexion and abduction-extension and internal rotation coupling with abduction-flexion and adduction-extension. Additionally, the translation of the proximal MC1 was predominantly radial during adduction and predominantly ulnar during abduction. The findings of this study aid in understanding thumb CMC joint mechanics and contextualize pathological changes for future treatment improvement.

Systematic review: Zone IV extensor tendon early active mobilization programs

STUDY DESIGN

Systematic review INTRODUCTION: Early active mobilization (EAM) of tendon repairs is preferred to immobilization or passive mobilization. Several EAM approaches are available to therapists; however, the most efficacious for use after zone IV extensor tendon repairs has not been established.

PURPOSE OF THE STUDY

To determine if an optimal EAM approach can be identified for use after zone IV extensor tendon repairs based on current available evidence.

METHODS

Database searching was undertaken on May 25, 2022 using MEDLINE, Embase, and Emcare with further citation searching of published systematic/scoping reviews and searching of the Australian New Zealand Clinical Trials Registry, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials. Studies involving adults with repaired finger zone IV extensor tendons, managed with an EAM program, were included. Critical appraisal using the Structured Effectiveness Quality Evaluation Scale was performed.

RESULTS

Eleven studies were included, two were of moderate methodological quality, and the remainder was low. Two studies reported results specific to zone IV repairs. Most studies utilized relative motion extension (RME) programs; two utilized a Norwich program, and two other programs were described. High proportions of "good" and "excellent" range of motion (ROM) outcomes were reported. There were no tendon ruptures in the RME or Norwich programs; small numbers of ruptures were reported in other programs.

CONCLUSIONS

The included studies reported minimal data on outcomes specific to zone IV extensor tendon repairs. Most studies reported on the outcomes for RME programs which appeared to provide good ROM outcomes with low levels of complications. The evidence obtained in this review was insufficient to determine the optimal EAM program after zone IV extensor tendon repair. It is recommended that future research focus specifically on outcomes of zone IV extensor tendon repairs.

LEVEL OF EVIDENCE

I.

Outcomes at 3 Months of a Place and Active Hold Method of Flexor Tendon Rehabilitation Following Zone II Injury

Background: Previous studies have shown that outcomes following a place and active hold (PAH) are better than a passive flexion protocol after a two-strand core-suture repair of flexor tendons injuries in zone II. This study aims to determine the outcomes of a PAH protocol of flexor tendon rehabilitation following a four-strand core-suture plus an epitendinous suture repair of the flexor digitorum profundus (FDP) combined with a simple horizontal loop repair of the flexor digitorum superficialis (FDS). Methods: This is a prospective study of patients with complete injury to both flexor tendons in zone II. All tendons were repaired with a simple horizontal loop for FDS and four-strand core-suture plus epitendinous suture for FDP. The PAH protocol was used postoperatively for 6 weeks. The outcome was evaluated using flexion contracture and total active motion (TAM), interpreted using Strickland criteria and categorised as excellent, good, fair and poor at 6 weeks and 3 months. The linear regression model was used to determine predictors of outcomes. Results: The study included 32 patients with flexor tendon injury in 46 fingers. No repairs ruptured, and 24 (52%) digits achieved good or excellent motion 6 weeks after surgery using the Strickland criteria. According to the Strickland criteria, 41 (89%) digits ranked as excellent and good with no poor result at a 3-month follow-up. Four patients had 5-10° of flexion contracture. Age was the predictor of TAM at 6 weeks and accounted for 13% of its variation. Improvement of TAM from 6 weeks to 3 months was related to age and flexion contracture at 6 weeks. Conclusions: The PAH protocol can be considered a safe technique for flexor rehabilitation after four-strand core-suture repair of FDP in zone II. Level of Evidence: Level IV (Therapeutic).

Interplay of Forces and the Immune Response for Functional Tendon Regeneration

Tendon injury commonly occurs during sports activity, which may cause interruption or rapid decline in athletic career. Tensile strength, as one aspect of tendon biomechanical properties, is the main parameter of tendon function. Tendon injury will induce an immune response and cause the loss of tensile strength. Regulation of mechanical forces during tendon healing also changes immune response to improve regeneration. Here, the effects of internal/external forces and immune response on tendon regeneration are reviewed. The interaction between immune response and internal/external forces during tendon regeneration is critically examined and compared, in relation to other tissues. In conclusion, it is essential to maintain a fine balance between internal/external forces and immune response, to optimize tendon functional regeneration.

Sustained-Release Hydrogel-Based Rhynchophylline Delivery System Improved Injured Tendon Repair

During the injured flexor tendon healing process, tendon tissue is easy to form extremely dense adhesion with the surrounding tissue, which causes the serious influence of hand function recovery. Uncaria is widely used in clinic and its main composition, Rhynchophylline (Rhy), has been reported on its good therapeutic effect, which could effectively inhibit the intra-abdominal adhesion formation. However, the therapeutic effect of Rhy on tendon healing and adhesion formation is still unclear. Due to the short half-life of Rhy, hyaluronic acid (HA) sustained-release system for Rhy delivery was constructed and it could also avoid drug from the undesired loss during the transit. After Rhy delivery system was applied around the injured tendons, adhesion formation, gliding function and healing strength of tendons were evaluated. Our results showed that the gliding excursion and healing strength of repaired tendons were both significantly increased, as well as the adhesion was inhibited. From in vivo experiments, Rhy could be able to increase the expression of Col Ⅰ/Col Ⅲ and helped fibroblasts to ordered organization for tendon tissues. But for adhesion tissues, Rhy promoted the apoptosis and accelerated the degradation of extracellular matrix. In vitro study showed Rhy could help tenocytes stimulated with TGF-β1 to recover to normal cell functions involving cell proliferation and apoptosis level. Through high-throughput sequencing, we found that Rhy was involved in the regulation of Extracellular Matrix (ECM) signaling pathway. We draw a conclusion that Rhy enhanced the tendon healing and prevented adhesion formation through inhibiting the phosphorylation of Smad2. In a word, this sustained release system of Rhy may be a promising strategy for the treatment of injured tendons.

A randomized clinical trial comparing early active motion programs: Earlier hand function, TAM, and orthotic satisfaction with a relative motion extension program for zones V and VI extensor tendon repairs

STUDY DESIGN

Randomized clinical trial with parallel groups.

INTRODUCTION

Early active mobilization programs are used after zones V and VI extensor tendon repairs; two programs used are relative motion extension (RME) orthosis and controlled active motion (CAM). Although no comparative studies exist, use of the RME orthosis has been reported to support earlier hand function.

PURPOSE OF THE STUDY

This randomized clinical trial investigated whether patients managed with an RME program would recover hand function earlier postoperatively than those managed with a CAM program.

METHODS

Forty-two participants with zones V-VI extensor tendon repairs were randomized into either a CAM or RME program. The Sollerman Hand Function Test (SHFT) was the primary outcome measure of hand function. Days to return to work, QuickDASH (Disabilities of Arm, Shoulder and Hand) questionnaire, total active motion (TAM), grip strength, and patient satisfaction were the secondary measures of outcome.

RESULTS

The RME group demonstrated better results at four weeks for the SHFT score (P = .0073; 95% CI: -10.9, -1.8), QuickDASH score (P = .05; 95% CI: -0.05, 19.5), and TAM (P = .008; 95% CI: -65.4, -10.6). Days to return to work were similar between groups (P = .77; 95% CI: -28.1, 36.1). RME participants were more satisfied with the orthosis (P < .0001; 95% CI: 3.5, 8.4). No tendon ruptures occurred.

DISCUSSION

Participants managed using an RME program, and RME finger orthosis demonstrated significantly better early hand function, TAM, and orthosis satisfaction than those managed by the CAM program using a static wrist-hand-finger orthosis. This is likely due to the less restrictive design of the RME orthosis.

CONCLUSIONS

The RME program supports safe earlier recovery of hand function and motion when compared to a CAM program following repair of zones V and VI extensor tendons.

Evaluation of a continuous locking novel epitendinous suture pattern with and without a core locking-loop suture on the biomechanical properties of tenorrhaphy constructs in an ex vivo model of canine superficial digital flexor tendon laceration

OBJECTIVE

To evaluate the effect of a continuous locking novel epitendinous suture (nES) pattern with and without a core locking-loop (LL) suture on the biomechanical properties of ex vivo canine superficial digital flexor tendon (SDFT) tenorrhaphy constructs.

SAMPLE

54 cadaveric forelimb SDFTs from 27 musculoskeletally normal adult dogs.

PROCEDURES

Tendons were assigned to 3 groups (18 SDFTs/group): sharply transected and repaired with a core LL suture alone (group 1), an nES pattern alone (group 2), or a combination of a core LL suture and nES pattern (group 3). All constructs underwent a single load-to-failure test. Yield, peak, and failure loads; gap formation incidence; and mode of failure were compared among the 3 groups.

RESULTS

Mean yield, peak, and failure loads differed significantly among the 3 groups and were greatest for group 3 and lowest for group 1. Mean yield, peak, and failure loads for group 3 constructs were greater than those for group 1 constructs by 50%, 47%, and 44%, respectively. None of the group 3 constructs developed 3-mm gaps. The most common mode of failure was suture pulling through the tendon for groups 1 (12/18) and 2 (12/18) and suture breakage for group 3 (13/18).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested augmentation of a core LL suture with an nES pattern significantly increased the strength of and prevented 3-mm gap formation at the tenorrhaphy site in ex vivo canine SDFTs. In vivo studies are necessary to assess the effectiveness and practicality of the nES pattern for SDFT repair in dogs.

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.

Flexor tendon rehabilitation in the 21st century: A systematic review

STUDY DESIGN

Systematic review.

INTRODUCTION

The rehabilitation of patients following flexor tendon injury has progressed from immobilization to true active flexion with the addition of wrist motion over the last 75 years.

PURPOSE OF THE STUDY

This review specifically intended to determine whether there is evidence to support one type of exercise regimen, early passive, place and hold, or true active, as superior for producing safe and maximal range of motion following flexor tendon repair.

METHODS

The preferred reporting items for systematic review and meta-analysis (PRISMA-P 2015) checklist was utilized to format the review. Both reviewers collaborated on all aspects of the research, including identifying inclusion/exclusion factors, search terms, reading and scoring articles, and authoring the paper. Articles were independently scored by each reviewer using the Structured Effectiveness Quality Evaluation Scale (SEQES).

RESULTS

A total of nine intervention studies that included a rehabilitative comparison group were systematically reviewed: one pediatric, four comparing passive flexion protocols to place and hold flexion, and four comparing true active flexion to passive and/or place and hold flexion.

DISCUSSION

This review provides moderate to strong evidence that place and hold exercises provide better outcomes than passive flexion protocols for patients with two to six-strand repairs. The studies included in this review suffered from methodological limitations including short timeframes for follow-up, unequal group distribution, and limited attention to repair site strength.

CONCLUSIONS

Based on a lack of superior benefits following true active motion regimens, there is not sufficient evidence to support true active motion as an effective or preferable choice for flexor tendon rehabilitation at this time.

Home-based rehabilitation in the postoperative treatment of flexor tendon repair

OBJECTIVE

To evaluate the results and complications of flexor tendon repair in which a home-based rehabilitation program was utilized without the assistance of a hand therapist during the first 4postoperative weeks.

MATERIAL Y METHODS

Between July 2009 and July 2014, a total of 21 digits in 15 patients were treated in our institution for complete laceration of the flexor tendons within the flexor pulley system (zone 1 and 2). Passive and active exercises performed by the patients themselves were started the morning after the operation. Data, as range-of-motion and complications, were collected 6months after the surgery.

RESULTS

Fifteen digits had full recovery of flexion. One patient suffered a rupture in the fifth postoperative week. Ten of the 21 digits developed a flexion contracture of the proximal interphalangeal joint; in 5 the contracture was less or equal to 10° without impairment of function or aesthetics.

DISCUSSION

Over recent decades, specialized hand therapy has been of great importance in the postoperative treatment of hand diseases. Unfortunately, these professionals are not always available in our area in the first days after surgery. With this protocol, the patient is in charge of carrying out the postoperative exercises, which could lead to a worse final result and a higher rate of complications.

CONCLUSION

The home-based rehabilitation program yielded complete recovery of joint mobility in most cases with a low complication rate.

Patterns of strain and the determination of the safe arc of motion after subscapularis repair--A biomechanical study

This study characterizes the strain patterns and safe arcs for passive range of motion (ROM) in the superior and inferior subscapularis tendon in seven cadaveric shoulders, mounted for controlled ROM, after deltopectoral approach to the glenohumeral joint, including tenotomy of the subscapularis tendon 1 cm medial to its insertion on the lesser tuberosity. The tenotomy was repaired with end-to-end suture in neutral rotation. Strain patterns were measured during passive ROM in external rotation (ER), ER with 30° abduction (ER+30), abduction, and forward flexion in the scapular plane (SP) before and after surgery. Percentages were calculated from 35 trials corresponding to five trials of each motion across seven specimens. With ER of 0-30°, 89% of trials of superior subscapularis tendon and 100% of trials of inferior subscapularis tendon achieved strains >3%, with very similar patterns noted in ER+30. In abduction of 0-90°, 5.8% of trials of superior and 85.3% of trials of inferior tendon achieved >3% strain. With passive ROM in SP, 26.5% of trials reached 3% strain in superior tendon compared to 100% in inferior tendon. Strain patterns in abduction and SP differed significantly (p < 0.001). Selective tenotomy and repair of the superior subscapularis tendon with open reparative or reconstructive shoulder procedures, when feasible, may be favorable for protected early passive ROM and rehabilitation postoperatively.

Flexor tendon injuries in children: Rehabilitative options and confounding factors

Research pertaining to the rehabilitation of children with flexor tendon injuries is less prevalent than that in the adult population, and most authors agree that immobilization protocols comprise a safe and efficacious choice. This article presents suggested protocols and correlated literature regarding the outcomes of immobilization, early passive motion, and early active motion in the pediatric population. Confounding factors which influence rehabilitative choices, both personal and environmental, are also presented.

Biomechanical comparison of double grasping repair versus cross-locked cruciate flexor tendon repair

PURPOSE

This study was conducted to compare the in vitro biomechanical properties of tensile strength and gap resistance of a double grasping loop (DGL) flexor tendon repair with the established four-strand cross-locked cruciate (CLC) flexor tendon repair, both with an interlocking horizontal mattress (IHM) epitendinous suture. The hypothesis is that the DGL-IHM method which utilizes two looped core sutures, grasping and locking loops, and a single intralesional knot will have greater strength and increased gap resistance than the CLC-IHM method.

METHODS

Forty porcine tendons were evenly assigned to either the DGL-IHM or CLC-IHM group. The tendon repair strength, 2-mm gap force and load to failure, was measured under a constant rate of distraction. The stiffness of tendon repair was calculated and the method of repair failure was analyzed.

RESULTS

The CLC-IHM group exhibited a statistically significant greater resistance to gapping, a statistically significant higher load to 2-mm gapping (62.0 N), and load to failure (99.7 N) than the DGL-IHM group (37.1 N and 75.1 N, respectively). Ninety percent of CLC-IHM failures were a result of knot failure whereas 30 % of the DGL-IHM group exhibited knot failure.

CONCLUSIONS

This study demonstrates that the CLC-IHM flexor tendon repair method better resists gapping and has a greater tensile strength compared to the experimental DGL-IHM method. The authors believe that while the DGL-IHM provides double the number of sutures at the repair site per needle pass, this configuration does not adequately secure the loop suture to the tendon, resulting in a high percentage of suture pullout and inability to tolerate loads as high as those of the CLC-IHM group.

Rehabilitation of the upper extremity following nerve and tendon reconstruction: when and how

Following upper extremity nerve and tendon reconstruction, rehabilitation is necessary to achieve optimal function and outcome. In this review, the authors present current evidence and literature regarding the strategies and techniques of rehabilitation following peripheral nerve and tendon reconstruction.

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.

Rehabilitation following hand transplantation

BACKGROUND

Hand allotransplantation can restore motor, sensory and cosmetic functions to upper extremity amputees. Over 70 hand transplant operations have been performed worldwide, but there is little published regarding post-hand transplant rehabilitation.

METHODS

The Brigham and Women's Hospital (BWH) Hand Transplantation Team's post-hand transplant rehabilitation protocol is presented here. The protocol must be modified to address each transplant recipient's unique needs. It builds on universally used modalities of hand rehabilitation such as splinting, edema and scar management, range of motion exercises, activities of daily living training, electrical stimulation, cognitive training and strengthening.

RESULTS

The BWH hand transplant rehabilitation protocol consists of four phases with distinct goals, frequency, and modalities. (1) Pre-operative: functional assessments are completed and goals and expectations of transplantation are established. (2) Initial post-operative (post-operative weeks 1-2): hand protection, minimization of swelling, education, and discharge. (3) Intermediate (post-operative weeks 2-8): therapy aims to prevent and/or decrease scar adhesion, increase tensile strength, flexibility and function, and prevent joint contractures. (4) Late (from 8 weeks forward): maximization of function and strength, and transition to routine activities. The frequency of rehabilitation therapy decreases gradually from the initial to late phases.

CONCLUSIONS

Rehabilitation therapy after hand transplantation follows a progressive increase in activity in parallel with wound healing and nerve regeneration. Careful documentation of progress and outcomes is essential to demonstrate the utility of interventions and to optimize therapy protocols.

Performance of a knotless four-strand flexor tendon repair with a unidirectional barbed suture device: a dynamic ex vivo comparison

With increased numbers of reports using barbed sutures for tendon repairs we felt the need to design a specific tendon repair method to draw the best utility from these materials. We split 30 sheep deep flexor tendons in two groups of 15 tendons. One group was repaired with a new four-strand barbed suture repair method without knot. The other group was repaired with a conventional four-strand cross-locked cruciate repair method (Adelaide repair) with knot. Dynamic testing (3-30 N for 250 cycles) and additional static pull to failure was performed to investigate gap formation and final failure forces. The barbed suture repair group showed higher resistance to gap formation throughout the test. Additionally final failure force was higher for the barbed suture group compared with the conventional repair group. When used appropriately, barbed suture materials could be beneficial to use in tendon surgery, especially with regard to early loading of the repair site and gap formation.

Flexor tendon excursion and load during passive and active simulated motion: a cadaver study

The aim of this study was to quantify the amount of tendon excursion and load experienced during simulated active and passive rehabilitation exercises. Six cadaver specimens were utilized to examine tendon excursion and load. Lateral fluoroscopic images were used to measure the excursions of metal markers placed in the flexor digitorum superficialis and profundus tendons of the index, middle, and ring fingers. Measurements were performed during ten different passive and active simulated motions. Mean tendon forces were higher in all active versus passive movements. Blocking movements placed the highest loads on the flexor tendons. Active motion resulted in higher tendon excursion than did passive motion. Simulated hook position resulted in the highest total tendon excursion and the highest inter-tendinous excursion. This knowledge may help optimize the management of the post-operative exercise therapy regimen.

Current flexor and extensor tendon motion regimens: a summary

This article summarizes select multinational early motion protocols. Included are flexor and extensor protocols for digital tendon repair in many forms. Custom orthosis design, exercise regimens, and advanced techniques are examples of what to expect. The goal of the article is to expose the reader to new ideas, educate regarding advanced techniques in tendon rehabilitation, and stimulate independent study to further the reader's skill set.

Managing the injured tendon: current concepts

Despite advances in understanding of the mechanical aspects of tendon management with improved suture technique and early stress application with postoperative therapy, clinical results remain inconsistent after repair, especially within the synovial regions. Complementary research to enhance the intrinsic pathway of healing, suppress the extrinsic pathway of healing, and manipulate frictional resistance to tendon gliding is now the focus of current basic science research on tendons. In the future, application of these new biologic therapies may increase the "safety zone" (or tolerance for load and excursion without dysfunctional gapping) as therapists apply stress to healing tendons and may alter future rehabilitation protocols by allowing greater angles of motion (and thus tendon excursion), increased external load, and decreased time in protective orthoses (splints). However, at this time, the stronger repair techniques and the application of controlled stress remain the best and most well-supported intervention after tendon injury and repair in the recovery of functional tendon excursion and joint range of motion. The hand therapist's role in this process remains a critical component contributing to satisfactory outcomes.

Adipose-derived stem cells enhance primary tendon repair: biomechanical and immunohistochemical evaluation

BACKGROUND

Primary tendon repair aims at increased tensile strength at the time of mobilisation. Tendon repair and regeneration using mesenchymal stem cells have been described in different studies; however, adipose-derived stem cell (ASC) use for tendon regeneration and repair has recently been taken into consideration. In this study, we sought to determine whether ASCs would be beneficial in primary tendon healing.

MATERIALS AND METHODS

Both the Achilles tendons of rabbits (n = 6) were incised and consequently repaired. To the left side was applied platelet-rich plasma (PRP) gel and to the right side autologous ASC-mixed PRP. The tensile strength was measured on the 4th week. The samples were taken for immunohistochemical evaluation of collagen type I, transforming growth factor beta (TGF-β) 1, 2, 3, fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF).

RESULTS

The tensile strengths in control and experimental groups were found out to be 29.46 ± 3.66 and 43.06 ± 3.80 kgf. Collagen type I, FGF and VEGF levels were statistically higher, whereas TGF-β1, 2, 3 were lower in the experimental group.

CONCLUSION

ASCs enhance primary tendon healing; however, the complex interaction and the cascades by which ASCs could increase collagen type I, FGF and VEGF and decrease TGF-β levels should further be investigated.

The effects of edema and self-adherent wrap on the work of flexion in a cadaveric hand

PURPOSE

Early motion protocols after flexor tendon repair often require hand therapy in edematous digits. Self-adherent wraps are used in the postoperative period to reduce edema. The purpose of this study was to determine whether the presence of a self-adherent wrap affected the work of flexion during early motion protocols.

METHODS

In an unpreserved cadaveric hand, the flexor digitorum profundus and flexor pollicis longus tendons were identified and attached to a tensile testing machine to measure work of flexion (WoF). We simulated subcutaneous edema by injecting normal saline into the digits. Moderate and severe edema was simulated by 10% and 20% increases in circumference of the digits, respectively. We evaluated 2 commonly used products: 2.5-cm Coban self-adherent wrap (3M, St. Paul, MN) and 2.5-cm Co-Wrap cohesive bandage (Hartmann, Rock Hill, SC). Statistical analyses include analysis of variance, 95% confidence intervals for average responses, and graphical display of both data and model predictions.

RESULTS

In digits without edema or wraps, WoF ranged from 0.0114 J (small finger) to 0.0710 J (thumb). Without wraps, simulated moderate and severe edema was predicted to increase WoF by an average of 23% and 71%, respectively. Application of self-adherent wrap increased WoF values significantly in all digits. In the majority of conditions tested, application of self-adherent wrap increased WoF more significantly than moderate edema did. The effects of edema and self-adherent wrap were additive, producing WoF values 4 times the baseline values.

CONCLUSIONS

Edema and self-adherent wrap increased WoF in this model. Therapists and surgeons should be aware of increased stress placed on tendons when early motion protocols are initiated in the presence of edema and self-adherent wrap.

CLINICAL RELEVANCE

We recommend removal of self-adherent wrap before starting a therapy session.

Repair of flexor digitorum profundus to distal phalanx: a biomechanical evaluation of four techniques

PURPOSE

Many techniques for repair of the flexor digitorum profundus to the distal phalanx show excessive gapping with variable clinical results. The purpose of this study was to test the biomechanical characteristics of an anchor-button (AB) technique, as compared to 3 other techniques.

METHODS

Twenty-four fresh-frozen human cadaveric fingers were randomized to 4 groups, 6 in each: group 1, 2-strand Bunnell suture button pullout technique; group 2, modified Kessler suture and 2 retrograde anchors; group 3: locking Krakow suture with 2 retrograde anchors; group 4, AB technique incorporating a 2-part repair, consisting of a locking dorsal Krakow suture with 2 retrograde anchors and a locking palmar Krakow suture fixed with a button. Tendon-to-bone gapping was measured after cyclical loading. Ultimate load to failure was measured at the end of 500 cycles.

RESULTS

The AB technique resulted in significantly less gapping when compared to the other techniques. It also resulted in a significantly stronger repair compared to all the other groups with an average load to failure comparable to the native tendon-to-bone interface.

CONCLUSIONS

The AB repair might allow for early active postoperative motion after repair of flexor digitorum profundus avulsion injuries and tendon reconstruction procedures; however, the soft tissue effects of this multistrand technique are unknown in clinical repairs.

Flexor tendon repair using a new suture technique: a comparative in vitro biomechanical study

INTRODUCTION

The purpose of this experimental study was to evaluate the biomechanical characteristics of two new four-strand core suture techniques for flexor tendon repair.

MATERIALS AND METHODS

The two new suture techniques (Marburg 1, Marburg 2) are characterized by four longitudinal stitches which are anchored by a circular or semicircular suture. They were compared with three commonly used core suture techniques (modified Kessler, Tsuge, Bunnell). Fifty porcine flexor tendons were randomly assigned to one of the five core suture techniques. Outcome measures included ultimate tensile strength, maximum of lengthening, mode of failure and 1 mm gap formation force.

RESULTS

The highest ultimate tensile strength was found for the modified Kessler technique (115 N). Both new techniques showed an ultimate load exceeding 50 N (57 N for Marburg 1, 54 N for Marburg 2). The Marburg 1 technique showed the highest gap resistance of all tested suture techniques. The Bunnell and Tsuge core suture techniques produced the poorest mechanical performance.

CONCLUSION

From these experimental results, the new Marburg 1 core suture technique can be considered for flexor tendon repair in a clinical setting with the use of active motion protocols.

Differentiation of adipose-derived stem cells for tendon repair

The goal of primary tendon repair is to increase tensile strength at the time of mobilization. Tendon repair and regeneration using mesenchymal stem cells have been described in several studies; however, the use of adipose derived stem cells (ASCs) for tendon repair has only recently been considered. In order to establish a suitable experimental model for the primary tendon repair using ASCs, this chapter describes the detailed methods for: (1) isolating stem cells from adipose tissue, (2) generation of a primary tendon injury and repair model, (3) evaluating functional restoration by measuring tensile strength, and (4) investigating the mechanisms involved in ASC-mediated tendon healing by histological and immunohistochemical analyses. Topical administration of ASCs to the site of injury accelerates tendon repair, as exhibited by a significant increase in tensile strength, direct differentiation of ASCs toward tenocytes and endothelial cells, and increases in angiogenic growth factors. These findings suggest that ASCs may have a positive effect on primary tendon repair and may be useful for future cell-based therapy.

The effects of core suture purchase on the biomechanical characteristics of a multistrand locking flexor tendon repair: a cadaveric study

PURPOSE

To determine the effects of suture purchase on work of flexion (WOF), 2-mm gap force, and load to failure on the combination cross-locked cruciate-interlocking horizontal mattress (CLC-IHM) flexor tendon repair in zone II.

METHODS

A total of 33 fresh-frozen cadaveric fingers were mounted in a custom jig, and the flexor digitorum profundus of each finger was fixed to the mobile arm of a tensile strength machine. Initial measurements of WOF were obtained. Each tendon was repaired with the CLC core suture, randomly assigned to placement of 3, 5, 7 or 10 mm from the cut edge of the tendon, and completed with the IHM circumferential suture. After the repair was completed, measurements of WOF were repeated. Each finger was cycled 1000 times. After each 250 cycles, gapping was recorded, and WOF was measured again. Change in WOF (WOF after repair - WOF of intact tendon) was calculated. Tendons were then dissected from the fingers and linearly tested for 2-mm gap force and ultimate load to failure.

RESULTS

The group repaired at 10 mm had the lowest percent increase in WOF (5.2%), the highest 2-mm gap force (89.8 N), and the highest ultimate load to failure (111.5 N). The group repaired at 3 mm had the highest percent increase in WOF (22.1%), the lowest 2-mm gap force (54.6 N), and the lowest ultimate load to failure (84.6 N).

CONCLUSIONS

A 10-mm suture purchase is the recommended distance for optimal performance for the CLC-IHM combination repair method. This method with a 10-mm suture purchase has a low increase in WOF, high strength, and high resistance to gapping, and it should be strong enough to tolerate early motion.

Complications of extensor tendon repairs at the extensor retinaculum

Literature describing surgical, post-operative management and outcomes following EDC repairs in close proximity to or within the extensor retinaculum is limited. This complex injury can result in decreased wrist and digital motion as well as loss of independent motion of the digits. This paper reviews complications following such injuries observed clinically as well as experimental simulation performed on cadaveric specimens. Our observations have direct implications to hand therapy practice and outcomes used following such injuries.

Biomechanical analysis of partial flexor tendon lacerations in zone II of human cadavers

PURPOSE

The aims of this study were to examine nonrepaired 90% partial lacerations of human cadaver flexor digitorum profundus (FDP) tendon after simulated active motion, and to assess the residual ultimate tensile strength.

METHODS

Partial, transverse zone II flexor tendon lacerations were made in the volar 90% of the tendon substance in 10 FDP tendons from 5 fresh-frozen human cadaver hands. The tendons were cycled in the curvilinear fashion described by Greenwald 500 times to a tension 25% greater than the maximum in vivo active FDP flexion force measured by Schuind and colleagues. The tendons were then loaded to failure using the same curvilinear model.

RESULTS

No tendons ruptured during cycling. Triggering occurred in 3 tendons. All 3 began triggering early in the cycling process, and continued to trigger throughout the remainder of the 500 cycles. The observed triggering mechanics in each case involved the interaction of the proximal face of the lacerated tendon with Camper's chiasm and the pulley edges during extension. The load to failure value of the 90% partially lacerated tendons averaged 141.7 +/- 13 N (mean +/- standard deviation). Tendon failure occurred by delamination of the intact collagen fibers from the distal, discontinuous 90% of the tendon.

CONCLUSIONS

Cadaveric transverse zone II partial flexor tendon lacerations have residual tensile strength greater than the force required for protected active mobilization.

Gliding distance of the extensor pollicis longus tendon with respect to wrist positioning: observation in the hands of healthy volunteers using high-resolution ultrasonography

STUDY DESIGN

Cross-sectional experimental bench.

INTRODUCTION

Optimal tendon gliding is necessary for normal thumb function.

PURPOSE OF THE STUDY

Measure the gliding distance of the extensor pollicis longus (EPL) tendons during passive thumb flexion from high-resolution echo images at four wrist positions.

METHODS

Gliding distance of the EPL tendon in zone 4 of the thumb was measured during passive flexion in four different wrist positions in 25 healthy female volunteers. Tendon gliding was evaluated from high-resolution ultrasonography in a frame-by-frame cross-correlation analysis.

RESULTS

Mean gliding distance of the EPL tendon was 1.79, 2.45, 1.09, and 1.36 mm with the wrist positioned in neutral, 30 degrees of extension, 30 degrees of flexion, and 20 degrees of ulnar deviation, respectively. There were statistically significant differences in the gliding distance of the EPL tendon among all of four wrist positions except for that between the wrist flexion and wrist ulnar deviation conditions.

CONCLUSIONS

Wrist extension induces the greatest magnitude EPL tendon gliding.

Effect of interleukin-10 overexpression on the properties of healing tendon in a murine patellar tendon model

PURPOSE

Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine shown to inhibit scar formation in fetal wound healing. The role of IL-10 in adult tendon healing and scar formation, however, remains unknown. The objective of this study is to investigate the effect of IL-10 overexpression on the properties of adult healing tendon using a well-established murine model of tendon injury and a lentiviral-mediated method of IL-10 overexpression.

METHODS

A murine model of patellar tendon injury was used and animals divided into 3 groups. Mice received bilateral patellar tendon injections with a lentiviral vector containing an IL-10 transgene (n = 34) or no transgene (n = 34). Control mice (n = 34) received injections of sterile saline. All animals then were subjected to bilateral, central patellar tendon injuries 2 days after injection and were killed at 5, 10, 21, and 42 days after injury. IL-10 content was analyzed by immunohistochemistry (n = 4/group). Tendon healing was evaluated by histology (n = 4/group) and biomechanical analysis (n = 10/group).

RESULTS

Overexpression of IL-10 in patellar tendon was confirmed after injection of the lentiviral vector. IL-10 immunostaining was increased at day 10 in the IL-10 group relative to that in controls. Histologically, there was no significant difference in angular deviation between groups at day 21, but a trend toward decreased angular deviation in controls relative to that in empty vector group mice was seen at day 42. Biomechanically, the IL-10 group showed significantly increased maximum stress at day 42 relative to that in controls. Percent relaxation showed a trend toward an increase at day 10 and a significant increase at day 42 in the IL-10 group relative to that in controls.

CONCLUSIONS

This study demonstrates successful gene transfer of IL-10 into adult murine patellar tendon using a lentiviral vector. Although the effects of overexpression of IL-10 on adult tendon healing have not yet been fully elucidated, the current study may help to further clarify the mechanisms of tendon injury and repair.

Biomechanical study of cross-locked cruciate versus Strickland flexor tendon repair

PURPOSE

Zone II flexor tendon repairs may create a bulging effect with resistance to tendon gliding. A biomechanical study was performed comparing the 4-strand cross-locked cruciate (CLC) to a 4-strand Strickland repair, both with and without an interlocking horizontal mattress (IHM) suture, in terms of strength characteristics and work of flexion.

METHODS

Sixteen fresh-frozen human fingers were placed in a custom jig. Flexor digitorum profundus tendons were sectioned at the A3 pulley level. Fingers were separated into 2 repair groups: 4-strand CLC and 4-strand Strickland core suture. Work of flexion was determined for each group, with and without an IHM circumferential suture. Final repair including IHM was tested for 2-mm gap failure and ultimate load to failure.

RESULTS

The CLC-IHM had a significantly smaller increase in work of flexion than the Strickland-IHM. For both suture types, the circumferential suture resulted in a statistically significant increase in work of flexion; however, peak entry force produced upon entry of the repair into the A2 pulley was reduced, although the decrease was not statistically significant for each group. The CLC-IHM had a significantly higher ultimate load to failure.

CONCLUSIONS

(1) The CLC-IHM suture method is stronger with less work of flexion than the Strickland-IHM method. (2) This new, combination repair method of CLC core suture with IHM circumferential suture is biomechanically superior to the commonly performed Strickland-IHM technique.

Flexor tendon repair using the two-strand side-locking loop technique to tolerate aggressive active mobilization immediately after surgery

BACKGROUND

Early mobilization after tendon repair decreases adhesion formation and improves repair-site strength. We investigated whether the two-strand side-locking loop technique would tolerate aggressive active mobilization immediately after surgery.

METHODS

Twelve flexor digitorum profundus tendons of the porcine forelimbs were sutured by the two-strand side-locking loop technique with a cross-stitch epitendinous repair (Group A), and by the 8-strand repair method with a simple running suture (Group B). Gaps and residual tensile strength after cyclic loadings of 3-50 N (for 10,000 rounds) were measured.

FINDINGS

Gaps after cyclic loading in Group A were 0.5+/-0.3 and 1.2+/-0.8 mm while those in Group B were 3.5+/-0.8 and 5.2+/-1.2 mm at 3 and 50 N, respectively. In addition, the respective residual tensile strength of Groups A and B were 207.1+/-15.2 and 84.2+/-18.3N.

INTERPRETATION

A combination of the two-strand side-locking loop technique with cross-stitch epitendinous repair served as the optimum suture method in establishing safe and early active mobilization without the aid of a specialized rehabilitation staff.

Biomechanic comparison of the Teno Fix tendon repair device with the cruciate and modified Kessler techniques

PURPOSE

To compare the mechanical behavior of a novel internal tendon repair device with commonly used 2-strand and 4-strand repair techniques for zone II flexor tendon lacerations.

METHODS

Thirty cadaveric flexor digitorum profundus tendons were randomized to 1 of 3 core sutures: (1) cruciate locked 4-strand technique, (2) modified Kessler 2-strand core suture technique, or (3) Teno Fix multifilament wire tendon repair device. Each repair was tested in the load control setting on a Instron controller coupled to an MTS materials testing machine load frame by using an incremental cyclic linear loading protocol. A differential variable reluctance transducer was used to record displacement across the repair site. Cyclic force (n-cycles) to 1-mm gap and repair failure was recorded using serial digital photography.

RESULTS

There was no significant difference in differential variable reluctance transducer displacement between the cruciate, modified Kessler, and Teno Fix repairs. The cruciate repair had greater resistance to visual 1-mm repair-site gap formation and repair-site failure when compared with the Kessler and Teno Fix repairs. No significant difference was found between the modified Kessler repair and the Teno Fix repair. In all specimens, the epitenon suture failed before the core suture. Repair failure occurred by suture rupture in the 7 cruciate specimens that failed, with evidence of gap formation before failure. Seven of 10 modified Kessler repairs failed by suture rupture. All of the Teno Fix repairs failed by pullout of the metal anchor.

CONCLUSIONS

The Teno Fix repair system did not confer a mechanical advantage over the locked cruciate or modified Kessler suture techniques for zone II lacerations in cadaveric flexor tendons during cyclic loading in a linear testing model. This information may help to define safe boundaries for postoperative rehabilitation when using this internal tendon repair device.

Zone I flexor tendon rehabilitation with limited extension and active flexion

This article describes an immediate active motion protocol for primary repair of zone I flexor tendons treated with tendon to tendon, or tendon to bone repair, and reviews clinical results. A rehabilitation protocol is proposed that will limit excursion of the zone I repair by blocking full distal interphalangeal (DIP) extension and by applying controlled active tension to both the unrepaired flexor digitorum superficialis (FDS) and the repaired flexor digitorum profundus (FDP). The rehabilitation technique utilized a dorsal protective splint with a relaxed position of immobilization with 30 degrees of wrist flexion, 40 degrees of metacarpophalangeal (MP) joint flexion, and a neutral position for the proximal interphalangeal (PIP) joints without dynamic traction. In addition, within the confines of the dorsal splint, the involved DIP joint was splinted at 40-45 degrees to prevent DIP joint extension during the early wound healing phases. Relaxed composite flexion was used to apply active tension to both the uninjured FDS, and the repaired FDP. This technique applies excursion of approximately 3 mm to the zone I tendon in a limited arc (45-75 degrees). The modified position of active flexion applies low loads of force (< 500 g), even with drag considered. This technique is supported by previous mathematical studies of excursion and internal tendon force, and clinical experience. Forty nine cases treated over a 10-year period were reviewed, and eight were excluded for incomplete follow-up. The use of this protocol for 41 zone I flexor digitorum profundus repairs by 12 different surgeons using varied surgical techniques was evaluated. None of the tendon to tendon repairs used more than two suture strands for the core repairs. Mean total active range of motion was 142 degrees (PIP 95 degrees plus DIP 47 degrees), or 81% of normal. Three tendons ruptured in non-protocol-related incidents and were excluded from the study. Results from this clinical study support the use of limited DIP extension combined with active tension with conventional repair in zone I.

The scientific basis for advances in flexor tendon surgery

During the last 40 years, there has been an enormous amount of basic scientific research designed to improve our knowledge of the structure of tendons, the biomechanics of their action, their biologic response to injury and repair, the mechanical characteristics of various tendon suture methods, and the effect of postrepair motion stress on tendon strength and healing. These investigative efforts have given rise to improved methods of tendon repair and protocols for the early application of passive and active wrist and digital motion as a means to more rapidly increase the strength and gliding of repaired tendons. The surgical techniques of hand surgeons and the rehabilitation protocols of hand therapists have improved enormously from these scientific efforts and the results of flexor tendon repair have become much more reliable. This article attempts to review many of the important scientific reports dealing with flexor tendons that have been published during the last three-plus decades and indicate how those works have improved our management of these difficult injuries.

New perspectives on extensor tendon repair and implications for rehabilitation

This article reviews the available biomechanical and clinical studies on extensor tendon repair and postoperative management. Immobilization has been a foundation for the postoperative treatment of these injuries, with good or excellent results ranging between 54% and 95%. However, clinical outcomes have consistently improved when utilizing rehabilitation involving either dynamically assisted or active motion, with good or excellent results achieved in at least 90% of cases. In addition, available biomechanical studies concerning finger extension strength, tendon repair strength, tendon shortening, resultant loss of motion, and gliding capability have validated controlled motion as biomechanically sound utilizing contemporary repair techniques.

The evolution of early mobilization of the repaired flexor tendon

The most important difference between the various approaches to postoperative digital flexor tendon rehabilitation is how the repaired tendon is treated during the first three to six weeks, in the earliest stages of healing. Early mobilization is the most commonly reported method of managing the healing flexor tendon. There are many different protocols and abundant research to support published approaches to tendon management. With so many choices, today's hand therapist must understand not only what those choices are, but also why and when to use them. There is no one correct way to manage a repaired flexor tendon; the specialist who does not understand how current techniques evolved is ill-equipped to design the appropriate treatment for a given patient. This article presents an overview of management options and how they have been developed over time, with special attention to changes in splint and exercise design in the crucial first few weeks after repair.

Rehabilitation after flexor tendon repair, reconstruction, and tenolysis

Flexor tendon rehabilitation after injury and surgical intervention has progressed over the last several decades. This evolution has left a vast amount of information for the hand therapy clinician. The hand therapist treating a primary flexor tendon repair can easily feel daunted, confused, and apprehensive because of the sheer amount of information before him or her, which may lead to patient treatment with a textbook or cookbook approach. This article outlines the history of flexor tendon programs and their evidenced-based development so that the clinician can approach each patient individually and progress them with a personalized, tailored approach in close communication with the surgeon. Successful flexor tendon rehabilitation's end-result is functional hand motion and strength. As experimental studies on improved surgical techniques continue to develop, more clinical research to support rehabilitation techniques that lead to good hand function results are necessary.

Repair of zone II flexor digitorum profundus lacerations using varying suture sizes: a comparative biomechanical study

PURPOSE

To compare the maximum tensile load, change in work of flexion, and gapping at the repair site after zone II flexor digitorum profundus tendon repairs using 2-0, 3-0, and 4-0 braided polyester 4-strand locked cruciate repair technique in fresh-frozen cadaveric hands with standard 6-0 suture epitenon repairs, to determine which suture size is the best for a core repair.

METHODS

A randomized study was designed using 41 tendons from 15 fresh-frozen cadaveric hands. We included only the flexor digitorum profundus tendons from the index, middle, and ring fingers to minimize variation between digits. Core suture size was randomized for each finger. A sharp laceration through the flexor digitorum profundus in zone II was made and a 4-strand locked cruciate braided polyester core stitch was performed along with a locked epitenon stitch. Cyclic loading was performed for 1,000 cycles. For each tendon the mean work of flexion (before/after zone II repair) and maximum tensile load were measured using a custom-designed tensiometer, as was gapping before maximum tensile loading.

RESULTS

Mean gaps after 1,000 load-unload cycles to 3.9 N of pulp pinch did not approach the clinically significant limit of 3 mm in each group. By using a regression model, we found that the prerepair and postrepair comparisons for mean work of flexion to a 3.9-N pulp pinch showed the greatest change in work of flexion for 2-0 braided polyester. Statistical significance was found between 2-0 braided polyester and 3-0 or 4-0 braided polyester; however, the work of flexion between the 3-0 and 4-0 polyester was not clinically significant. The highest maximum tensile load was obtained with suture size 2-0 braided polyester. The maximal tensile load statistically showed 2-0 braided polyester to be stronger than 4-0 braided polyester but we found no statistically significant difference between 3-0 and 2-0 braided polyester or between 3-0 and 4-0 braided polyester.

CONCLUSIONS

In this cadaveric study we found that increasing locking cruciate suture caliber from 4-0 to 2-0 increased maximum tensile strength but also caused increased work of flexion. Gapping was not affected by suture caliber. There was no significant difference in strength or mean change in work of flexion between 3-0 or 4-0 braided polyester sutures.

Flexor digitorum profundus tendon tension during finger manipulation

Abstract The purpose of this study was to measure the tension in the flexor digitorum profundus (FDP) tendon in zone II and the digit angle during joint manipulations that replicate rehabilitation protocols. Eight FDP tendons from eight human cadavers were used in this study. The dynamic tension in zone II of the tendon and metacarpophalangeal (MCP) joint angle were measured in various wrist and digit positions. Tension in the FDP tendon increased with MCP joint extension. There was no tension with the finger fully flexed and wrist extended (synergistic motion), but the tendon force reached 1.77 +/- 0.43 N with the MCP joint hyperextended 45 degrees with the distal interphalangeal and proximal interphalangeal joints flexed. The combination of wrist extension and MCP joint hyperextension with the distal interphalangeal and proximal interphalangeal joints fully flexed, what the authors term "modified synergistic motion," produced a modest tendon tension and may be a useful alternative configuration to normal synergistic motion in tendon rehabilitation.

Pyramid of progressive force exercises to the injured flexor tendon

Postoperative rehabilitation for patients who have sustained a laceration to their flexor tendon apparatus is an important factor in maximizing functional outcome. Quality rehabilitation is characterized by the development of a tailored exercise regimen. There is currently no model available to tailor an exercise regimen for a person with an atypical physiologic response pattern. If rehabilitation protocols were classified according to the criteria of forces applied across a tendon juncture and/or excursion, and a clinical method were available to assist in the identification of optimal tendon loading and/or excursion application, then those individuals with atypical response patterns could be treated more efficiently and effectively. The author conducted a literature review and case study. A model for systematic application of progressive loading exercises to the intrasynovial flexor tendon injury and repair is conceptually developed. The model consists of a pyramidal series of eight specific rehabilitation exercises in the following sequence: passive protected extension, place and hold, active composite fist, hook and straight fist, isolated joint motion, resistive composite fist, resistive hook and straight fist, and resistive isolated joint motion. Concepts are developed to implement a three-point clinical adhesion-grading system. Clinical application of the system is highlighted. An excellent outcome was considered 112% total active motion. A model for systematic application of progressive loading exercises has been conceptually developed in concert with a method for determination of optimal tendon loading. Further substantiation is necessary to validate the proposed theory.

Early active motion flexor tendon protocol using one splint

This article describes an early active motion protocol for use after a four-strand flexor tendon repair. The protocol uses a simple dorsal blocking splint with the wrist in neutral and four fingers in rubber band traction for the first five weeks, then gradually advances the patient over the next seven weeks. The patient is able to perform the exercises without changing the splint at home during the first five weeks of the protocol. The results of the retrospective chart review are promising. Of 40 digits, 95% experienced excellent and good results in zone II, and 87.5% experienced excellent and good results in zones I, II, and III. One rupture (2.5%) occurred in a noncompliant patient. The DASH scale was used to determine functional outcome, with results of 7.82 on the physical function/symptoms category, 16.07 in sports/ performing arts, and 10.23 in the work category.

Vascular anatomy of the human flexor digitorum profundus tendon insertion

The vascular anatomy of the flexor digitorum profundus (FDP) tendon insertion is described by using a vascular injection and modified Spalteholtz tissue clearing protocol in 36 human cadaver digits. A consistent dense palmar and dorsal vascular supply to the tendon at its insertion into the distal phalanx was observed based on sources from both the distal phalanx and the vinculum brevis profundus. Multiple palmar-dorsal vascular interconnections were seen between these spatially distinct vascular networks, a finding not observed previously in studies of the vascular anatomy of tendon or ligament insertions. Additionally a well-defined dorsal zone of hypovascularity was identified subjacent to the volar plate of the distal interphalangeal joint, within 1 cm of the tendon insertion. Recognition of the vascular supply to the FDP insertion at the distal phalanx permits further evaluation of the vascular, histologic, and cellular events after FDP tendon avulsion and improves the understanding of the biologic response mechanisms involved in bone-tendon healing.

Flexor tendon and peripheral nerve repair

Any restoration of hand function following tendon and nerve injury has to include the repair or replacement of the hand's ability to perform a great many tasks. It is hard at first to appreciate fully the loss that occurs with flexor tendon injury. With loss of flexor tendons operating at the fingers or thumb, they cannot be fully closed and the hand is impaired for grasp and release as it interfaces with objects. But, sensibility can also be compromised from tendon injury even without direct injury to nerve, as object recognition in the absence of vision requires finger movement. When peripheral nerve injury is combined with flexor tendon injury, sensibility is directly impaired. There is a loss in the sense of finger or thumb position, pain, temperature, and touch/pressure recognition, in addition to the tendon injury.

A prospective, controlled, randomized trial comparing early active extension with passive extension using a dynamic splint in the rehabilitation of repaired extensor tendons

This prospective, randomized, controlled trial compared two methods of rehabilitating extensor tendon repairs in zones IV-VIII. Group A patients followed an early active mobilization regimen and Group B patients followed a dynamic splintage regimen. Data on 19 patients in Group A and 17 patients in Group B were collected at 4 weeks and at final follow-up (3 months median follow-up for both groups). Extension lag, flexion deficit and total active motion (TAM) were measured. At 4 weeks, patients in Group B had a better TAM (median 87%, range 56-102%) compared to patients in Group A (median 77%, range 52-97%). At final follow-up, there were no significant differences in the results of the two groups. There were no ruptures in either group.

Comparative biomechanical performances of 4-strand core suture repairs for zone II flexor tendon lacerations

To compare the biomechanical performances of six 4-strand flexor tendon repairs at zone II, we used an in situ testing model in 54 cadaver profundus tendons. The techniques studied were the modified Becker, modified double Tsuge, Lee, locked cruciate, Robertson, and Strickland. Prerepair and postrepair comparisons for work of flexion to a 3.9-N pulp pinch (equal to 12.6 N tendon force) showed the greatest interference to gliding in the modified Becker repair and the least in the modified double Tsuge repair. Mean gaps after 1,000 load-unload cycles to a 3.9-N pulp pinch did not approach the clinically important limit of 3 mm in all groups. Ultimate tensile strength was highest in the modified Becker (69.4 +/- 8.2 N) but not significantly higher than the modified double Tsuge (60.3 +/-15.3 N) and locked cruciate (64.1 +/- 16.2 N). In all repair groups the mean pulp pinch forces upon failure were well above values recommended for active mobilization protocols that use external load guides. The locked cruciate, modified double Tsuge, and modified Becker repairs were strong enough for an early active motion protocol after surgery. Locked cruciate and modified double Tsuge were easier to perform and provided less interference to tendon gliding than the modified Becker repair.

Effect of arm elevation and rotation on the strain in the repaired rotator cuff tendon. A cadaveric study

In 14 cadaveric shoulders, a rotator cuff tear (2 cm wide and 1.5 cm long) was created and repaired under a 3-kg tensile force with the arm in adduction. Strain on the repaired tendon was measured at 0 degrees, 15 degrees, 30 degrees, and 45 degrees of elevation in the sagittal, scapular, and coronal planes and from 60 degrees of internal rotation to 60 degrees of external rotation. The strain in all of the planes decreased significantly with the arm elevated more than 30 degrees. With 30 degrees of elevation in the scapular and coronal planes, the strain increased in internal rotation and decreased in external rotation. In all of the positions measured, the strain in the sagittal plane was significantly greater than in the other planes. We concluded that more than 30 degrees of elevation in the coronal or scapular plane and rotation ranging from 0 degrees to 60 degrees of external rotation compose the safe range of motion after repair of the rotator cuff.