Intrasynovial Flexor Tendon Repair Research Articles

Current trends in the prevention of adhesions after zone 2 flexor tendon repair.

Treating flexor tendon injuries within the digital flexor sheath (commonly referred to as palmar hand zone 2) presents both technical and logistical challenges. Success hinges on striking a delicate balance between safeguarding the surgical repair for tendon healing and initiating early rehabilitation to mitigate the formation of tendon adhesions. Adhesions between tendon slips and between tendons and the flexor sheath impede tendon movement, leading to postoperative stiffness and functional impairment. While current approaches to flexor tendon repair prioritize maximizing tendon strength for early mobilization and adhesion prevention, factors such as pain, swelling, and patient compliance may impede postoperative rehabilitation efforts. Moreover, premature mobilization could risk repair failure, necessitating additional surgical interventions. Pharmacological agents offer a potential avenue for minimizing inflammation and reducing adhesion formation while still promoting normal tendon healing. Although some systemic and local agents have shown promising results in animal studies, their clinical efficacy remains uncertain. Limitations in these studies include the relevance of chosen animal models to human populations and the adequacy of tools and measurement techniques in accurately assessing the impact of adhesions. This article provides an overview of the clinical challenges associated with flexor tendon injuries, discusses current on- and off-label agents aimed at minimizing adhesion formation, and examines investigational models designed to study adhesion reduction after intra-synovial flexor tendon repair. Understanding the clinical problem and experimental models may serve as a catalyst for future research aimed at addressing intra-synovial tendon adhesions following zone 2 flexor tendon repair.

The Effects of NF-κB Suppression on the Early Healing Response Following Intrasynovial Tendon Repair in a Canine Model.

The highly variable clinical outcomes noted after intrasynovial tendon repair have been associated with an early inflammatory response leading to the development of fibrovascular adhesions. Prior efforts to broadly suppress this inflammatory response have been largely unsuccessful. Recent studies have shown that selective inhibition of IKK-β, an upstream activator of NF-κB signaling, mitigates the early inflammatory response and leads to improved tendon healing outcomes. In the current study, we test the hypothesis that oral treatment with the IKK-β inhibitor ACHP (2-amino-6-[2-(cyclopropylmethoxy)-6-hydroxyphenyl]-4-piperidin-4-yl nicotinenitrile an inhibitor) will modulate the post-operative inflammatory response and improve intrasynovial flexor tendon healing. To test this hypothesis, the flexor digitorum profundus tendon of 21 canines was transected and repaired within the intrasynovial region and assessed after 3 and 14 days. Histomorphometry, gene expression analyses, immunohistochemistry, and quantitative polarized light imaging (QPLI) were used to examine ACHP-mediated changes. ACHP led to reduction in phosphorylated p-65, indicating that NF-κB activity was suppressed. ACHP enhanced expression of inflammation-related genes at 3 days and suppressed expression of these genes at 14 days. Histomorphometry revealed enhanced cellular proliferation and neovascularization in ACHP-treated tendons compared to time-matched controls. These findings demonstrate that ACHP effectively suppressed NF-κB signaling and modulated early inflammation, leading to increased cellular proliferation and neovascularization without stimulating the formation of fibrovascular adhesions. Together, these data suggest that ACHP treatment accelerated the inflammatory and proliferative phases of tendon healing following intrasynovial flexor tendon repair. This article is protected by copyright. All rights reserved.

Metabolic regulation of intrasynovial flexor tendon repair: The effects of dichloroacetate administration on early tendon healing in a canine model.

Enriched in glycolytic enzymes, paucicellular and hypovascular intrasynovial flexor tendons fail to mount an effective healing response after injury and repair. In contrast, well-vascularized extrasynovial flexor tendons possess high levels of oxidative phosphorylation (OXPHOS) enzymes and have a markedly improved healing capacity. This study was designed to compare the metabolic profiles of the two types of tendons and to evaluate the impact of metabolic reprogramming on early intrasynovial tendon healing in a clinically relevant canine model. Results showed that healthy intrasynovial tendons expressed higher levels of PDK1 and GAPDH and lower levels of SCX and IGF1 than did extrasynovial tendons. PDK1 encodes a subtype of pyruvate dehydrogenase kinase (PDK) that inhibits OXPHOS. Consistently, ATP production via glycolysis was favored in intrasynovial tendon cells whereas OXPHOS was the preferred pathway in extrasynovial tendon cells. Inhibition of glycolysis in vitro increased SCX expression in intrasynovial tendon cells. Therefore, dichloroacetate (DCA), a PDK1 inhibitor, was used in vivo to shift intrasynovial tendon ATP production from glycolysis to OXPHOS. Oral DCA administration reduced serum lactate concentration and increased acetyl-CoA content in repaired intrasynovial tendons and led to reduced TLR4 and IL1B and increased IGF1, SCX, and TGFB3 expressions in treated intrasynovial tendons compared to controls. Immunohistochemistry staining with anti-Ki67 and anti-CD31 antibodies revealed marked increases in cellularity and neovascularization in treated intrasynovial tendons. Clinical significance: The findings of this experiment indicate that improved gene expression and histological outcomes can be achieved by regulating glucose metabolism in the early stages following intrasynovial tendon repair.

Prognostic factors for digital range of motion after intrasynovial flexor tendon injury and repair: Long-term follow-up on 273 patients treated with active extension-passive flexion with rubber bands

Study DesignObservational cohort study. IntroductionInvestigating prognostic factors using population-based data may be used to improve functional outcome after flexor tendon injury and repair. Purpose of the StudyThe aim of this study is to investigate the effect of concomitant nerve transection, combined flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendon transection and the age of the patient, on digital range of motion (ROM) more than 1 year after FDP tendon transection and repair in zone I and II. MethodsTwo hundred seventy-three patients with a total of 311 fingers admitted for FDP injury in zone I and II were treated with active extension-passive flexion with rubber bands and followed for at least 1 year. We compared outcome by evaluating digital mobility using Strickland's evaluation system. ResultsAt 12 months 72% of patients aged > 50 had fair or poor ROM compared to 17% of patients aged 0-25 years. At 24 months the results for patients aged > 50 had improved to 33% with fair or poor ROM, whereas no improvement had occurred for patients aged 0-25 (17% with fair or poor ROM). Concomitant nerve transection and FDS tendon transection had no negative effects on digital mobility. DiscussionAge above 50 was significantly associated with impaired digital ROM during the first year after flexor tendon injury and repair but not at 2 years follow-up. Concomitant nerve transection and combined transection of FDP and FDS do not affect digital mobility. ConclusionsOlder patients are likely to have a slower healing process and impaired digital ROM during the first year after surgery.

Effect of connective tissue growth factor delivered via porous sutures on the proliferative stage of intrasynovial tendon repair.

Recent growth factor, cell, and scaffold-based experimental interventions for intrasynovial flexor tendon repair have demonstrated therapeutic potential in rodent models. However, these approaches have not achieved consistent functional improvements in large animal trials due to deleterious inflammatory reactions to delivery materials and insufficient induction of targeted biological healing responses. In this study, we achieved porous suture-based sustained delivery of connective tissue growth factor (CTGF) into flexor tendons in a clinically relevant canine model. Repairs with CTGF-laden sutures were mechanically competent and did not show any evidence of adhesions or other negative inflammatory reactions based on histology, gene expression, or proteomics analyses at 14 days following repair. CTGF-laden sutures induced local cellular infiltration and a significant biological response immediately adjacent to the suture, including histological signs of angiogenesis and collagen deposition. There were no evident widespread biological effects throughout the tendon substance. There were significant differences in gene expression of the macrophage marker CD163 and anti-apoptotic factor BCL2L1; however, these differences were not corroborated by proteomics analysis. In summary, this study provided encouraging evidence of sustained delivery of biologically active CTGF from porous sutures without signs of a negative inflammatory reaction. With the development of a safe and effective method for generating a positive local biological response, future studies can explore additional methods for enhancing intrasynovial tendon repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2052-2063, 2018.

Combined Administration of ASCs and BMP-12 Promotes an M2 Macrophage Phenotype and Enhances Tendon Healing.

Outcomes after intrasynovial tendon repair are highly variable. An intense inflammatory cascade followed by a delayed healing response can cause adhesion formation and repair-site failure that severely impair the function of repaired digits. No effective remedies exist to fully address these issues. Cell- and growth factor-based therapies have been shown to modulate inflammation and improve cell proliferation and matrix synthesis and therefore are promising treatment approaches for intrasynovial tendon repair. (1) Can autologous adipose-derived mesenchymal stromal cells (ASCs) and recombinant bone morphogenetic protein-12 (rBMP-12) be effectively delivered to an intrasynovial flexor tendon repair without adverse effects? (2) Do autologous ASCs modulate the inflammatory response after intrasynovial tendon injury and repair? (3) Does the combined application of autologous ASCs and rBMP-12 modulate the proliferative and remodeling responses after intrasynovial tendon injury and repair? Sixteen 1- to 2-year-old female canines were used in this study. Autologous ASC sheets, with and without rBMP-12, were applied to the surface of sutured flexor tendons. Fourteen days after repair, the effects of treatment were determined using quantitative PCR (six per group) for the expression of genes related to macrophage phenotype or inflammation (IL-4, CD163, VEGF, NOS2, IL-1B, and IFNG), cell proliferation (CCND1), and tendon formation (SCX, TNMD, COL1A1 and COL3A1). Proteomics analysis (four per group) was performed to examine changes in tendon protein abundances. CD146 immunostaining and hematoxylin and eosin staining (four per group) were used to detect tendon stem or progenitor cells and to semiquantitatively evaluate cellularity at the tendon repair; analyses were done blinded to group. Gross inspection and cell tracing showed that autologous ASCs and rBMP-12 were delivered to the flexor tendon repair site without the deleterious effects of adhesion and repair-site gap formation. Quantitative assessment of gene and protein expression showed effects of treatment: ASC-sheet treatment modulated the postrepair inflammatory response and facilitated healing by increasing regenerative M2 macrophages (M2 marker CD204, twofold of normal, p = 0.030), inflammatory inhibitor (prostaglandin reductase 1 [PTRG1], 1.6-fold of normal, p = 0.026), and proteins involved in tendon formation (periostin [POSTN], 1.9-fold of normal, p = 0.035). Consistently, semiquantitative and qualitative evaluations of repaired tissue showed that ASC-sheet treatment reduced mononuclear cell infiltration (12% less than nontreated tendons, p = 0.021) and introduced CD146+ stem or progenitor cells to the repair site. The combined administration of ASCs and rBMP-12 further stimulated M2 macrophages by increasing IL-4 (116-fold of normal, p = 0.002) and led to the increase of M2 effector matrix metalloproteinase-12 involved in matrix remodeling (twofold of normal, p = 0.016) and reduction of a negative regulator of angiogenesis and cell migration (StAR-related lipid transfer domain protein13 [STARD13]; 84% of normal, p = 0.000), thus facilitating the proliferative stage of tendon repair. ASCs and BMP-12 accelerated the progression of healing in the proliferative stage of tendon repair. The effects of ASCs and BMP-12 on tendon functional recovery should be evaluated in future studies. The cell sheet approach is an effective, biocompatible, and surgeon-friendly approach for cell and growth factor delivery during tendon repair. Combined application of ASCs and BMP-12 may accelerate intrasynovial tendon healing while suppressing the adverse inflammatory response.

The effect of mesenchymal stromal cell sheets on the inflammatory stage of flexor tendon healing.

BackgroundThe clinical outcomes following intrasynovial flexor tendon repair are highly variable. Excessive inflammation is a principal factor underlying the formation of adhesions at the repair surface and affecting matrix regeneration at the repair center that limit tendon excursion and impair tendon healing. A previous in-vitro study revealed that adipose-derived mesenchymal stromal cells (ASCs) modulate tendon fibroblast response to macrophage-induced inflammation. The goal of the current study was therefore to explore the effectiveness of autologous ASCs on the inflammatory stage of intrasynovial tendon healing in vivo using a clinically relevant animal model.MethodsZone II flexor tendon transections and suture repairs were performed in a canine model. Autologous ASC sheets were delivered to the surface of repaired tendons. Seven days after repair, the effects of ASCs on tendon healing, with a focus on the inflammatory response, were evaluated using gene expression assays, immunostaining, and histological assessments.ResultsASCs delivered via the cell sheet infiltrated the host tendon, including the repair surface and the space between the tendon ends, as viewed histologically by tracking GFP-expressing ASCs. Gene expression results demonstrated that ASCs promoted a regenerative/anti-inflammatory M2 macrophage phenotype and regulated tendon matrix remodeling. Specifically, there were significant increases in M2-stimulator (IL-4), marker (CD163 and MRC1), and effector (VEGF) gene expression in ASC-sheet treated tendons compared with nontreated tendons. When examining changes in extracellular matrix expression, tendon injury caused a significant increase in scar-associated COL3A1 expression and reductions in COL2A1 and ACAN expression. The ASC treatment effectively counteracted these changes, returning the expression levels of these genes closer to normal. Immunostaining further confirmed that ASC treatment increased CD163+ M2 cells in the repaired tendons and suppressed cell apoptosis at the repair site.ConclusionsThis study provides a novel approach for delivering ASCs with outcomes indicating potential for substantial modulation of the inflammatory environment and enhancement of tendon healing after flexor tendon repair.

The Impact of Suture Caliber and Core Suture Strands on Intrasynovial Flexor Tendon Repair: Not a clinical study

The Impact of Suture Caliber and Core Suture Strands on Intrasynovial Flexor Tendon Repair: Not a clinical study

The Effect of Core and Epitendinous Suture Modifications on Repair of Intrasynovial Flexor Tendons in an In Vivo Canine Model

To determine in vivo effects of modifications to core and epitendinous suture techniques in a canine intrasynovial flexor tendon repair model using clinically relevant rehabilitation. Our null hypothesis was that gap formation and rupture rates would remain consistent across repair techniques. We evaluated gap formation and rupture in 75 adult mongrel dogs that underwent repair of intrasynovial flexor tendon lacerations followed by standardized postoperative therapy. The current suture technique was a 4-0, 8-strand core suture with a purchase of 1.2 cm and a 5-0, epitendinous suture repair with a 2-mm purchase length and depth. We compared gap and failure by chi-square analysis to a historical group of in vivo repairs (n = 76) from the same canine model using 8-strand core suture repair with purchase of 0.75 cm and 6-0 epitendinous suture with a 1-mm purchase length and depth. A total of 93% of tendons (n = 70) demonstrated gapping of less than 3 mm using the current suture technique. Five percent of tendons (n = 4) had a gap of 3 mm or greater, and there was 1 repair site failure. This was significantly improved over the comparison group of historical 8-strand core repair technique, which resulted in 82% (n = 62) of repairs with a gap of less than 3 mm and 7 failures (9%). In an in vivo model, current modifications to suture techniques for intrasynovial flexor tendon repair demonstrated significant improvements in gap formation and rupture compared with a similar technique using shorter purchase lengths and shallower purchase depth. Suggested repair modifications for the treatment of zone II flexor tendon transections demonstrate improvements in gap formation and tendon rupture in vivo.

Intrasynovial flexor tendon repair: A biomechanical study of variations in suture application in human cadavera

To improve the functional outcomes of intrasynovial tendon suture, prior experiments evaluated individual technical modifications used in the repair process. Few studies, however, have assessed the combinatorial effects of those suture modifications in an integrated biomechanical manner, including a sample size sufficient to make definitive observations on repair technique. Two hundred fifty-six flexor tendon repairs were performed in human cadavera, and biomechanical properties were determined. The effects of five factors for flexor tendon repair were tested: core suture caliber (4-0 or 3-0), number of sutures crossing the repair site (four- or eight-strand), core suture purchase (0.75 or 1.2 cm), peripheral suture caliber (6-0 or 5-0), and peripheral suture purchase (superficial or 2 mm). Significant factors affecting the properties of the repair were the number of core suture strands and the peripheral suture purchase. The least significant factors were core suture purchase and peripheral suture caliber. The choice of core suture caliber affected the properties of repair marginally. Based on these results, we recommend that surgeons continue to focus on multi-strand repair methods, as the properties of eight-strand repairs were far better than those of four-strand repairs. To resist gap formation and enhance repair strength, a peripheral suture with 2 mm purchase is also recommended. Finally, since core suture caliber affected some biomechanical properties, including the failure mode, a 3-0 suture could be considered, provided that future in vivo studies can confirm that gliding properties are not adversely influenced.

Repair of Flexor Carpi Radialis Tendon Laceration at the Wrist in a Professional Ice Hockey Player

The flexor carpi radialis is a wrist flexor and radial deviator with half the relative strength of flexor carpi ulnaris. In the majority of patients, the flexor carpi radialis tendon is expendable and is routinely used for various reconstructive procedures about the hand and wrist. Isolated flexor carpi radialis lacerations at the wrist are rare. Flexor carpi radialis tendon ruptures, which have been reported in association with distal radius fractures, longstanding osteoarthritis, and percutaneous treatment of scaphoid fractures, are usually treated non-operatively. We report a case of a traumatic laceration of the flexor carpi radialis tendon at the wrist in a professional ice hockey player. Surgical repair and rehabilitation using established principles for intrasynovial flexor tendon repair allowed return to sport at the professional level in 2 months.Tension-free core suture repair was performed with a modified-Kessler, 4-strand repair using a double-stranded 4-0 Supramid suture. A running epitendinous suture was then placed around the circumference of the tendon with 6-0 Prolene. Immobilization of the wrist in 20° of flexion was maintained for 2 weeks. Full active and passive digital motion was allowed immediately postoperatively and continued throughout the rehabilitation. Therapy was initiated at 2 weeks postoperatively with full passive wrist flexion and passive wrist extension to a dorsal block of 20°. At 4 weeks postoperatively, a dorsal splint was fabricated to keep the wrist in neutral. At this time, active extension to a dorsal block of zero and full passive flexion was allowed. Active wrist flexion without resistance was begun at 6 weeks, and full strengthening was allowed at 8 weeks postoperatively. The patient returned to sport at the professional level shortly thereafter. At latest follow-up, the patient has been able to fully participate in professional ice hockey without pain or functional limitation.

Technical and Biological Modifications for Enhanced Flexor Tendon Repair

Clinical outcomes after intrasynovial flexor tendon repair have been substantially improved over the past 2 decades through advances in tendon suture techniques and postoperative rehabilitation methods. Nevertheless, complications such as repair site elongation (i.e., gap formation) and rupture continue to occur frequently. Experimental studies have shown that repair site strength fails to increase in the first 3 weeks after tendon suture. After 3 weeks, the strength and rigidity of the repair site improve significantly, a process that continues for several months. Formation of a repair site gap during the early rehabilitation period has been shown to considerably delay the accrual of repair site strength over time. Thus, it is of prime importance that the method of tendon suture achieves and maintains a stiff and strong repair site during the early healing interval by maintaining close approximation of the tendon stumps and by stimulating, where possible, the intrinsic repair response. In this review, we describe recent efforts to enhance the integrity of the immature repair site. We focus on 2 major areas of advancement: surgical technique modifications and manipulation of the biologic and biochemical environment.

Enhanced flexor tendon healing through controlled delivery of PDGF‐BB

A fibrin/heparin-based delivery system was used to provide controlled delivery of platelet derived growth factor BB (PDGF-BB) in an animal model of intrasynovial flexor tendon repair. We hypothesized that PDGF-BB, administered in this manner, would stimulate cell proliferation and matrix remodeling, leading to improvements in the sutured tendon's functional and structural properties. Fifty-six flexor digitorum profundus tendons were injured and repaired in 28 dogs. Three groups were compared: (1) controlled delivery of PDGF-BB using a fibrin/heparin-based delivery system; (2) delivery system carrier control; and (3) repair- only control. The operated forelimbs were treated with controlled passive motion rehabilitation. The animals were euthanized at 7, 14, and 42 days, at which time the tendons were assessed using histologic (hyaluronic acid content, cellularity, and inflammation), biochemical (total DNA and reducible collagen crosslink levels), and biomechanical (gliding and tensile properties) assays. We found that cell activity (as determined by total DNA, collagen crosslink analyses, and hyaluronic acid content) was accelerated due to PDGF-BB at 14 days. Proximal interphalangeal joint rotation and tendon excursion (i.e., tendon gliding properties) were significantly higher for the PDGF-BB-treated tendons compared to the repair-alone tendons at 42 days. Improvements in tensile properties were not achieved, possibly due to suboptimal release kinetics or other factors. In conclusion, PDGF-BB treatment consistently improved the functional but not the structural properties of sutured intrasynovial tendons through 42 days following repair.

The Early Effects of Sustained Platelet-Derived Growth Factor Administration on the Functional and Structural Properties of Repaired Intrasynovial Flexor Tendons: An In Vivo Biomechanic Study at 3 Weeks in Canines

A bioactive fibrin-based delivery system was used to provide sustained administration of platelet-derived growth factor (PDGF-BB) in a clinically relevant model of intrasynovial flexor tendon repair. We hypothesized that PDGF-BB administered in this manner would improve the sutured tendon's functional and structural properties 3 weeks after repair. A delivery system consisting of 30 microL of fibrin matrix, peptide, heparin, and 100 ng of PDGF-BB was incorporated into the repair sites of randomly selected medial or lateral forepaw flexor digitorum profundus tendons of 8 adult mongrel dogs. The remaining forepaw flexor digitorum profundus tendons were repaired without the growth-factor and fibrin-based delivery system and served as controls. The surgically treated forelimbs were treated with controlled passive motion rehabilitation. The animals were killed at 3 weeks, at which time the tendons were tested for range of motion with a motion analysis system and for tensile properties with a materials testing machine. Proximal interphalangeal joint and distal interphalangeal joint rotation values were significantly higher for the PDGF-BB-treated tendons compared with the repair-alone tendons. Excursion values were also significantly higher in the PDGF-BB-treated tendons. There were no significant differences in tensile properties when comparing PDGF-BB-treated with repair-alone tendons. The functional properties of repaired intrasynovial flexor tendons were significantly improved with the sustained administration of PDGF-BB. The failure to achieve improvements in ultimate load, stiffness, and strain in the experimental group may have been due to suboptimal PDGF-BB dosage or suboptimal release kinetics.

Measurement of Health Outcomes Following Tendon and Nerve Repair

The World Health Organization's model of health suggests that tendon and nerve injury outcomes can be assessed in terms of impairment, activity limitations, and participation restrictions. A tendon injury results in impairment of motion and strength of affected digits. Literature on outcome of tendon surgery has focused on active motion. Recently developed devices can be used to measure strength impairments associated with individual digits after tendon injury, although the importance of either grip or digital strength measures as indicators of post-tendon recovery has not been fully delineated. Published impairment rating scales have expressed outcome based on regained total active motion of relevant joints. These scales also tend to classify outcomes on a subjective four-point scale ranging from poor to excellent. Subjective ratings have not been validated, vary across scales, and inhibit meaningful comparisons by diluting information. Nerve injuries result in an impairment of motion, strength, sensibility, and sympathetic nerve function. Development of quantitative measures of sensibility continues to evolve, although all current methods have some limitations. Two-point discrimination was once a mainstay of assessment, but current evidence suggests it is less valid and responsive than other quantitative sensory testing. Cold sensitivity is common and can be measured through rewarming responses or by self-report. A comprehensive impairment rating scale for nerve injury with subscales addressing sensory, motor, and pain/discomfort domains has been developed. Use of this validated instrument will facilitate more meaningful comparisons across centers and studies. Recent literature on treatment outcomes has focused on impairment measures with minimal attention to activity limitations and participation restrictions. Validation of appropriate scales and inclusion of both impairment and disability measures in future clinical studies is required to fully understand health outcomes after tendon and nerve injury.

Recent Progress in Flexor Tendon Healing: The Modulation of Tendon Healing with Rehabilitation Variables

Until recently, attempts to optimize the postoperative regimen following intrasynovial flexor tendon repair had been essentially empirical, in that both the time and graduation of the exercise regimen have lacked clear conceptual guidelines. The magnitude of load applied in previous studies had not been clearly controlled, and similarly, the effects of increased repair site excursion and gap formation had not been evaluated in clinically relevant models. Recent experimental in vivo data on the application of force and excursion as independent variables by the authors and other investigators have helped to clarify the respective roles of these two variables. The goal of surgical treatment of intrasynovial flexor tendon lacerations is the achievement of a primary tendon repair of tensile strength sufficient to allow early controlled motion after surgery. The implementation of an appropriate postoperative rehabilitation protocol will, based on the experimental data discussed in this article, decrease the formation of intrasynovial adhesions, facilitate the restoration of the gliding surface, and stimulate the accrual of strength at the repair site.

A proposed model for systematic application of progressive force exercises to the intrasynovial flexor tendon injury and repair

Postoperative rehabilitation for patients who have sustained a laceration to their intrasynovial flexor tendon apparatus is an important factor in maximizing functional outcome. Quality rehabilitation is partially characterized by the development and implementation of a tailored exercise regimen. Though suggested strategies are available for tailoring rehabilitation programs according to age, learning capabilities, and suture technique, there is currently no system available to tailor an exercise regimen for a person with an atypical physiologic response pattern (i.e., heavy or light collagen synthesis). If flexor tendon rehabilitation protocols were classified according to the criterions of force and/or excursion, and a clinical method were available to assist in the identification of optimal force and/or excursion application, then those individuals with atypical response patterns could be treated more efficiently and effectively.

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.

Neovascularization of the flexor digitorum profundus tendon after avulsion injury: An in vivo canine study

Purpose: The changes in matrix material properties and intrinsic vascularization that have been noted in intrasynovial tendon stumps after avulsion injury may be of considerable clinical relevance with regard to the results of surgical repair. Our objective was to determine both the time course and the source of neovascularization of the tendon stump in an in vivo canine model of flexor digitorum profundus (FDP) avulsion after a clinically relevant delay in diagnosis. Method: The FDP tendon was released from bone directly by sharp dissection and the vinculum brevis profundus was lacerated, simulating an avulsion injury with interruption of the vascular supply to the tendon stump. After death at 7 and 21 days, tendon vascularity was evaluated with India ink injection and clearing using a modified Spalteholtz technique. Results: All 7-day specimens showed an absence of vascularity compared with the controls. In all 21-day specimens a direct vascular supply originated from local fibrovascular adhesions contacted the stump on its surface and blood vessels penetrated the tendon stump circumferentially. Progressive vascularization of the avulsed tendon stump occurred between 7 and 21 days after injury, originating from fibrovascular adhesions to the surrounding synovial sheath. Conclusions: Whereas previous studies of intrasynovial flexor tendon laceration and repair have shown a progressive proximal to distal neovascularization of the FDP during the early postoperative period, longitudinal proximal to distal growth from the proximal blood supply of the FDP was not observed toward the unrepaired tendon stump. (J Hand Surg 2003;28A:231-236. Copyright © 2003 by the American Society for Surgery of the Hand.)

FLEXOR TENDON REPAIR AND REHABILITATION

Basic science and clinical investigation have advanced significantly the treatment and the outcome following intrasynovial flexor tendon repair and rehabilitation and reconstruction over the past 30 years. The application of modern multistrand suture repair techniques as well as postoperative rehabilitation protocols emphasizing the application of intrasynovial repair site excursion has led to a protocol for treatment of intrasynovial flexor tendon lacerations emphasizing a strong initial repair followed by the application of postoperative passive motion rehabilitation. Protocols for the reconstruction of failed initial treatment have likewise undergone modification given new findings on the biologic and clinical behavior of flexor tendon grafts. Currently accepted treatment protocols following flexor tendon repair and reconstruction are based on current clinical and scientific data.