Zone-specific pitfalls in flexor tendon rehabilitation: management and prevention.

Despite significant advancements in flexor tendon repair techniques and rehabilitation strategies, achieving complete restoration of digital motion remains a formidable challenge. The most prevalent complications associated with tendon repair are the development of tendon adhesions and joint contractures. Left unaddressed, these complications can further lead to secondary pathomechanical changes, resulting in fixed deformities significantly affecting hand function. This review of zone-specific considerations in flexor tendon rehabilitation provides an in-depth analysis of the dynamics of tendon motion after repair and strategies to minimize common secondary complications.

Ultrasound Nanobubble Coupling Agent for Effective Noninvasive Deep-Layer Drug Delivery.

Conventional coupling agents (such as polyvinylpyrrolidone, methylcellulose, and polyurethane) are unable to efficiently transport drugs through the skin's dual barriers (the epidermal cuticle barrier and the basement membrane barrier between the epidermis and dermis) when exposed to ultrasound, hindering deep and noninvasive transdermal drug delivery. In this study, nanobubbles prepared by the double emulsification method and aminated hyaluronic acid are crosslinked with aldehyde-based hyaluronic acid by dynamic covalent bonding through the Schiff base reaction to produce an innovative ultrasound-nanobubble coupling agent. By amplifying the cavitation effect of ultrasound, drugs can be efficiently transferred through the double barrier of the skin and delivered to deep layers. In an in vitro model of isolated porcine skin, this agent achieves an effective penetration depth of 728 µm with the parameters of ultrasound set at 2 W, 650 kHz, and 50% duty cycle for 20 min. Consequently, drugs can be efficiently delivered to deeper layers noninvasively. In summary, this ultrasound nanobubble coupling agent efficiently achieves deep-layer drug delivery by amplifying the ultrasonic cavitation effect and penetrating the double barriers, heralding a new era for noninvasive drug delivery platforms and disease treatment.

Flexor Tendon Repair: Avoidance and Management of Complications.

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

Risk factors associated with tendon adhesions after hand tendon repair.

Background: Tendon adhesions after hand tendon repair are one of the most difficult complications of hand surgery and can cause severe disability. This study aimed to assess the risk factors associated with tendon adhesions after hand tendon repair to provide a theoretical foundation for the early prevention of tendon adhesions in patients with tendon injuries. Moreover, this study intends to increase doctors' awareness of the issue and serves as a reference for developing new prevention and treatment strategies. Methods: We retrospectively analyzed 1,031 hand trauma cases that underwent repair after finger tendon injury in our department between June 2009 and June 2019. Tendon adhesions, tendon injury zones, and other relevant information were collected, summarized, and analyzed. The significance of data was determined using a t-test or Pearson's chi-square test, and odds ratios (OR) were calculated using logistic regression tests to describe factors associated with post-tendon repair adhesions. Results: A total of 1,031 patients were enrolled in this study. There were 817 males and 214 females with an average age of 34.98 (2-82) years. The injured side included 530 left and 501 right hands. Postoperative finger tendon adhesions occurred in 118 cases (11.45%), including 98 males and 20 females, 57 left and 61 right hands. The risk factors for the total sample in the descending order were degloving injury, no functional exercise, zone II flexor tendon injury, time from injury to surgery >12 h, combined vascular injury, and multiple tendon injuries. The flexor tendon sample shared the same risk factors as the total sample. Risk factors for the extensor tendon sample were degloving injury, no functional exercise. Conclusions: Clinicians should pay close attention to patients with tendon trauma in hand having the following risk factors: degloving injury, zone II flexor tendon injury, lack of functional exercise, time from injury to surgery >12 h, combined vascular injury, and multiple tendon injuries. Due to the high risk of post-repair adhesions in patients with the conditions mentioned above, individualized treatment measures should be designed for the risk factors, and postoperative functional exercise of the hand is required.

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

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

The Use of an Adipofascial Flap to Prevent Extensor Tendon Adhesions After Plating of the Proximal Phalanx of the Fingers: A Comparative Study.

BACKGROUND: Extensor tendon adhesions occurring after proximal phalangeal (P1) fractures are not uncommon. A previous report described the use of an adipofascial flap (AFF) to prevent adhesions after dorsal plating of the P1. The purpose of the study is to examine the results of open reduction and internal fixation with the use of an AFF (F group) and without (N group, that is, no flap used) in a larger group of patients. METHODS: A retrospective study involving a period of 11 years was conducted involving results of 21 unstable fractures of the P1 of the fingers in 18 patients. In all, 12 fingers were treated without any flap (N group) and 9 fingers were treated with the AFF (F group). For each patient, the total active motion (TAM) ratio, and the grip strength (Jamar) ratio were assessed, and adverse effects and the 10-point visual analogue scale (VAS) score were recorded. For statistical analysis, sample characteristics were described using mean ± standard deviation and median, and a Bayesian approach was used for inferential analysis. RESULTS: In the F group, the TAM ratio (84% ± 13% vs 65% ± 17%) was higher with a lower rate of adverse effects (OR: 0.067, 95% CI, 0.0035-0.58,) and a lower VAS score with evidence of the positive effect of the AFF. The Jamar ratio was similar in the 2 groups (F group 80% ± 25% vs N group 79% ± 19%) with no associated effect of the AFF on grip strength. CONCLUSIONS: The AFF is a reliable tool to reduce adhesions between plates and the extensor apparatus of the P1 and may be useful to improve finger function after plating of P1 fractures. TYPE OF STUDY/LOE: Therapeutic, Retrospective, Level IV.

Quercetin reduces tendon adhesion in rat through suppression of oxidative stress.

BACKGROUND: Tendon adhesion is one of the most common clinical problems, which poses a considerable challenge to orthopedics doctors. Quercetin (QUE) as a popular drug at present, it has various biological functions, including anti-inflammatory, anti-ischemic, anti-peroxidation, and antioxidant. The purpose of this study was to investigate the effect of quercetin on tendon adhesion and whether quercetin can inhibit oxidative stress. METHOD: Thirty-six rats were randomly divided into three groups, including control group, low QUE (50 mg/kg/day) group, and high QUE (100 mg/kg/day) group. After 1 week, the levels of SOD, MDA and GPx were measured. The degree of tendon adhesion was assessed by macroscopic evaluation and histological evaluation. After 4 weeks. Besides, the pharmacological toxicity of quercetin to main organs were evaluated by histological analysis. RESULTS: The extent of superoxide dismutase (SOD) and glutathione peroxidase (GPx) of tendon tissue in high QUE group was significantly higher than those of low QUE group and control group. And the extent of malondialdehyde (MDA) of tendon tissue in high QUE group was significantly lower than that of low QUE group and control group. By macroscopic evaluation and histological analysis, the extent of tendon adhesion in high QUE group was lower than low QUE group and control group. However, there were no significant changes of the major organs through histological analysis. CONCLUSIONS: Quercetin may be a good and safe strategy in preventing tendon adhesion. But further clinical research is needed before its recommendation in the prevention and treatment of tendon adhesion.

Effect of Acellular Amnion With Increased TGF-ß and bFGF Levels on the Biological Behavior of Tenocytes.

The human amniotic membrane has been a subject for clinical and basic research for nearly 100 years, but weak rejection has been reported. The purpose of this research is to remove the cellular components of the amnion for eliminating its immune-inducing activity to the utmost extent. The amniotic membrane treated by acid removed the epithelial cell, fibroblast, and sponge layers and retained only the basal and dense layers. In vitro, biological effects of the new material on tenocytes were evaluated. The levels of transforming growth factor (TGF-ß1), fibroblast growth factor (bFGF) proteins were measured. In vivo, the tendon injury model of chickens was constructed to observe effects on tendon adhesion and healing. The acellular amniotic membrane effectively removed the cell components of the amnion while retaining the fibrous reticular structure. Abundant collagen fibers enhanced the tensile strength of amnion, and a 3D porous structure provided enough 3D space structure for tenocyte growth. In vitro, acellular amnion resulted in the fast proliferation trend for tenocytes with relatively static properties by releasing TGF-ß1 and bFGF. In vivo, the experiment revealed the mechanism of acellular amnion in promoting endogenous healing and barrier exogenous healing by evaluating tendon adhesion, biomechanical testing, and labeling fibroblasts/tendon cells and monocytes/macrophages with vimentin and CD68. The acellular amnion promotes endogenous healing and barrier exogenous healing by releasing the growth factors such as TGF-ß1 and bFGF, thereby providing a new direction for the prevention and treatment of tendon adhesion.

Outcomes of Secondary Combined Proximal Interphalangeal Joint Release and Zone II Flexor Tenolysis.

Background: Tendon adhesions and capsular contractures following trauma to the proximal interphalangeal joint (PIPJ) may significantly reduce hand function. Traditional, staged surgical management prioritizes restoration of PIPJ passive range of motion with joint release prior to restoration of active range of motion (AROM) with tenolysis. This is expensive and burdensome for patients. Our objective was to evaluate functional outcomes of combined PIPJ release and zone II flexor tenolysis. Methods: We retrospectively reviewed patients who underwent combined PIPJ release and flexor tenolysis. Replantation and tendon graft cases were excluded. Data were collected on pre- and postoperative AROM, total active motion (TAM), tip to distal palmar crease (DPC) distance, and grip strength. Functional outcomes were graded using the Boyes, American Society for Surgery of the Hand, and modified Strickland scores. Results: Twelve patients (9 men and 3 women, median age = 40 years) with a total of 15 digits underwent combined PIPJ release and flexor tenolysis a median of 10.1 months after injury. At a median follow-up of 4.0 months, there were significant improvements in median PIPJ AROM (15° to 70°), TAM (105° to 223°), tip to DPC distance (6.0 to 2.0 cm), and grip strength (35% to 54% of unaffected hand). Modified Strickland score was good in 46% of digits and excellent in 38%. There were no tendon ruptures, surgical site infections, or devascularized digits. Conclusion: Proximal interphalangeal joint stiffness is a challenging complication of hand trauma. Although a complete return to premorbid range of motion and function is rarely attained with surgery, improved outcomes may be consistently achieved with secondary combined PIPJ release and zone II flexor tenolysis.

Localized delivery of miRNAs targets cyclooxygenases and reduces flexor tendon adhesions.

The formation of adhesions during healing of an injured tendon remains a difficult problem in clinical practice. Local anti-inflammation gene delivery provides high local gene concentration, reduces the inflammatory response of the injured tendon microenvironment, and decreases systemic side effects to enhance in vivo efficacy. In this study, we designed a novel local sustained gene delivery system by using cyclooxygenase (COX-1 and COX-2)-engineered miRNA plasmid/nanoparticles embedded in hyaluronic acid (HA) hydrogel to reduce flexor tendon adhesions. The local sustained gene delivery system significantly downregulates COX-1 and COX-2 expression in the tendon tissue and the surrounding subcutaneous tissue. More importantly, this plasmid/nanoparticle hydrogel system significantly reduced tissue adhesion formation. This approach offers an effective therapeutic strategy to reduce tendon adhesions by directly targeting the down-regulation of COX-1 and COX-2 expression within the microenvironment of the injured tendon. STATEMENT OF SIGNIFICANCE: A local sustained gene delivery system was developed to regulate the expression of targeted genes in the specific time and location for tendon adhesion treatment. The engineered miRNA plasmid/nanoparticles embedded in hyaluronic acid hydrogel were synthesized to downregulate the expression of cyclooxygenases in the tendon tissue during the early stage of tendon healing with inflammatory response. This plasmid/nanoparticle hydrogel system offers an effective therapeutic strategy to attenuate the formation of tendon adhesion through direct downregulation of COX-1 and COX-2 expression within the microenvironment of the injured tendon.

Management of complications of extensor tendon injuries.

Treatment goals for the management of extensor tendon injuries include restoration of function, minimizing disability, and decreasing the risk of complications. These goals can be achieved with an accurate understanding of the zone-specific concerns for extensor tendon injuries, early referral to hand therapy, and active communication between hand surgeons and therapists. This article reviews extensor tendon injuries by zone, outlines optimal management strategies that help prevent complications, and describes the treatment of these complications.

Can an adipofascial flap be used to prevent adhesions after plating of the proximal phalanx? A case report.

Tendon adhesions in zone IV after proximal phalangeal fractures are common and may lead to loss of range of motion at the proximal interphalangeal joint. The type of fracture, surgical technique and rehabilitation strategy also influence the final functional outcome. Plate fixation is a reliable solution in cases of comminuted phalangeal fracture. This article describes how adhesions between the plate and extensor apparatus in cases of comminuted fractures of the proximal phalanx can be reduced by using an adipofascial flap.

Clinical study of the application of interscalene brachial plexus catheter plus functional exercise after tendon adhesion lysis / 中国现代医生

Objective To investigate the application effect of interscalene brachial catheter plus functional exercise af-ter tendon adhesion lysis. Methods A total of 40 patients with 68 fingers who hospitalized due to postoperative tendon adhesions of flexor tendon injury repair and the need of tendon adhesion lysis from January 2012 to December 2013 were chosen, and were randomly divided into group A and group B. Group A received scalene brachial plexus catheter analgesia, and group B received the conventional therapy. Knuckle total active activity and pain degree of the two groups were compared. Results There were significant differences in comparing knuckles TAM of group A before ad-ministration, group A after administration and group B after operation for 1 d to 1 week, and TAM good rate of group A after administration increased significantly. There were significant differences in comparing NRS scores of group A be-fore administration, group A after administration and group B, and pain of patients in group A after administration sig-nificantly improved(P<0.05). Conclusion Application of brachial plexus catheter analgesia can significantly reduce the pain of functional exercise, promote recovery of hand function in patients and reduce the incidence of tendon re-adhe-sions.

Down-regulating ERK1/2 and SMAD2/3 phosphorylation by physical barrier of celecoxib-loaded electrospun fibrous membranes prevents tendon adhesions.

Peritendinous adhesions, as a major problem in hand surgery, may be due to the proliferation of fibroblasts and excessive collagen synthesis, in which ERK1/2 and SMAD2/3 plays crucial roles. In this study, we hypothesized that the complication progression could be inhibited by down-regulating ERK1/2 and SMAD2/3 phosphorylation of exogenous fibroblasts with celecoxib. Celecoxib was incorporated in poly(l-lactic acid)-polyethylene glycol (PELA) diblock copolymer fibrous membranes via electrospinning. Results of an in vitro drug release study showed celecoxib-loaded membrane had excellent continuous drug release capability. It was found that celecoxib-loaded PELA membranes were not favorable for the rabbit fibroblast and tenocyte adhesion and proliferation. In a rabbit tendon repair model, we first identified ERK1/2 and SMAD2/3 phosphorylation as a critical driver of early adhesion formation progression. Celecoxib released from PELA membrane was found to down-regulate ERK1/2 and SMAD2/3 phosphorylation, leading to reduced collagen I and collagen Ⅲ expression, inflammation reaction, and fibroblast proliferation. Importantly, the celecoxib-loaded PELA membranes successfully prevented tissue adhesion compared with control treatment and unloaded membranes treatment. This approach offers a novel barrier strategy to block tendon adhesion through targeted down-regulating of ERK1/2 and SMAD2/3 phosphorylation directly within peritendinous adhesion tissue.