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Introduction: Tendon injuries of the hand present a diverse spectrum of challenges in emergency medicine, ranging from minor strains to catastrophic ruptures. The superficial anatomy of hand tendons predisposes them to various mechanisms of injury, leading to complex medical scenarios. Here, we present a unique case of flexor tendon exposure secondary to abscess formation and spontaneous rupture, emphasizing the importance of prompt recognition and management of such injuries in the emergency department. Case Report: A 69-year-old male with multiple comorbidities presented with diffuse pain and a pale, pulseless right lower extremity, alongside a left hand exhibiting exposed flexor tendons due to recent abscess drainage. Despite broad-spectrum antibiotics and pain management, the patient underwent above-knee amputation due to vascular compromise. Evaluation revealed a complete flexor tendon rupture likely attributable to infection, necessitating emergent hand surgery at the bedside. Conclusion: Understanding the nuances of tendon injuries is paramount for emergency physicians, given their potential for lifelong disability if inadequately addressed. Awareness of risk factors and appropriate management strategies, including early surgical intervention when indicated, is essential in optimizing patient outcomes. This case serves as a reminder of the complexities involved in hand injuries and underscores the need for vigilance and tailored care in the emergency setting.

This study evaluated the effects of a neuromuscular training (NMT) warm-up program on injury incidence, neuromuscular function, and program adherence, maintenance and acceptance in adolescent basketball players. A total of 275 players from 20 Slovenian teams (15 ± 1.7 years of age), were randomized into an intervention group (IG, n=129) and a control group (CG, n=146). Over three months, the IG incorporated NMT into their warm-ups, while the CG followed their usual practice. Measurements of body anthropometry, muscle contractile properties, and balance were taken before and after the intervention. Also, the injury incidence, training adherence and maintenance were reported. Both groups showed improved balance, with no significant difference between them. However, IG demonstrated reduced delay times in specific muscles, indicating improved neuromuscular function. Injury prevalence proportion (%) during the whole study period was higher in the control group compared to intervention (IG: 10.9% vs. CG: 23.3%), and incidence rate. Moreover, the incidence rate ratio for sustaining an injury was 2.6 on average (ranging from 0.88 to 7.07 for tendon and muscle injuries, respectively), indicating significantly lower injury risk in IG than CG. These findings highlight the effectiveness of NMT warm-ups in reducing injury risk and enhancing neuromuscular function, emphasizing the value of structured injury prevention strategies in youth sports.. [ABSTRACT FROM AUTHOR]

Musculoskeletal simulations are a useful tool for improving our understanding of the human body. However, the physiological validity of predicted kinematics and forces is highly dependent upon the correct calibration of muscle parameters and the structural integrity of a model's internal skeletal structure. In this study, we show how ill-tuned muscle parameters and unphysiological deformations of a model's skeletal structure can be detected by using muscle elements as sensors with which modelling and parameterization inconsistencies can be identified through muscle and tendon strain injury assessment. To illustrate our approach, two modelling issues were recreated. First, a model repositioning simulation using the THUMS AM50 occupant model version 5.03 was performed to show how internal model deformations can occur during a change of model posture. Second, the muscle material parameters of the OpenSim gait2354 model were varied to illustrate how unphysiological muscle forces can arise if material parameters are inadequately calibrated. The simulations were assessed for muscle and tendon strain injuries using previously published injury criteria and a newly developed method to determine tendon strain injury threshold values. Muscle strain injuries in the left and right musculus pronator teres were detected during the model repositioning. This straining was caused by an unphysiologically large gap (12.92 mm) that had formed in the elbow joint. Similarly, muscle and tendon strain injuries were detected in the modified right-hand musculus gastrocnemius medialis of the gait2354 model where an unphysiological reduction of the tendon slack length introduced large pre-strain of the muscle-tendon unit. The results of this work show that the proposed method can quantify the internal distortion behaviour of musculoskeletal human body models and the plausibility of Hill-type muscle parameter choice via strain injury assessment. Furthermore, we highlight possible actions to avoid the presented issues and inconsistencies in literature data concerning the material characteristics of human tendons. [ABSTRACT FROM AUTHOR]

Background: Recent advancements in artificial intelligence have proven their effectiveness in orthopaedic settings, especially in tasks like medical image analysis. This study compares human musculoskeletal radiologists to artificial intelligence in a novel, detailed, short, and cost-effective examination of Achilles tendon magnetic resonance images to uncover potential disparities in their reasoning approaches. Aiming to identify relationships between the structured assessment of the Achilles tendon and its function that could support injury prevention. We examined 72 athletes to investigate the link between Achilles tendon structure, as visualised in magnetic resonance images using a precise T2*-weighted gradient echo sequence with very short echo times, and its functional attributes. The acquired data were analysed using advanced artificial intelligence techniques and reviewed by radiologists. Additionally, we conducted statistical assessments to explore relationships with functional studies in four meaningful groups: dynamic strength, range of motion, muscle torque and stabilography. Results: The results show notable linear or non-linear relationships between functional indicators and structural alterations (maximal obtained Spearman correlation coefficients ranged from 0.3 to 0.36 for radiological assessment and from 0.33 to 0.49 for artificial intelligence assessment, while maximal normalised mutual information ranged from 0.52 to 0.57 for radiological assessment and from 0.42 to 0.6 for artificial intelligence assessment). Moreover, when artificial intelligence-based magnetic resonance assessment was utilised as an input, the associations consistently proved more robust, or the count of significant relationships surpassed that derived from radiological assessment. Ultimately, utilising only structural parameters as inputs enabled us to explain up to 59% of the variance within specific functional groups. Conclusions: This analysis revealed that structural parameters influence four key functional aspects related to the Achilles tendon. Furthermore, we found that relying solely on subjective radiologist opinions limited our ability to reason effectively, in contrast to the structured artificial intelligence assessment. Study Design: Cross-sectional studies. Key Points: •Establishment of a relationship between magnetic resonance imaging-based structural features and functional characteristics of the Achilles tendon, emphasising non-linear connections. •Introduction of a fast and efficient magnetic resonance imaging protocol for concurrent evaluation of structural and functional aspects, alongside a comparative analysis of artificial intelligence and radiologist reasoning capabilities. •Highlighting the advantages of artificial intelligence-driven reasoning in identifying structural biomarkers, offering potential enhancements for injury prevention strategies and personalised treatment approaches. [ABSTRACT FROM AUTHOR]

Degenerative tendinopathy results from the accumulation of minor injuries following unsuccessful tendon repair during acute tendon injuries. The process of tendon repair is prolonged and varies between individuals, making it susceptible to reinjury. Moreover, treating chronic tendinopathy often requires expensive and extensive rehabilitation, along with a variety of combined therapies to facilitate recovery. This condition significantly affects the quality of life of affected individuals, underscoring the urgent need for more efficient and cost-effective treatment options. Although traditional treatments have improved significantly and are being used as substitutes for surgical interventions, the findings have been inconsistent and conflicting. This review aims to clarify these issues by exploring the strengths and limitations of current treatments as well as recent innovations in managing various forms of degenerative tendinopathy. [ABSTRACT FROM AUTHOR]

Background: Participation in recreational and competitive sports can predispose people to musculoskeletal injuries. Chronic overuse with insufficient recovery, overloading, and direct contact can result in acute primary tendon ruptures. There is scarce literature regarding the epidemiology of sports-related acute primary tendon ruptures in the United States (US). Purpose: To identify the incidence rate (IR) of sports-related acute primary tendon ruptures presenting to US emergency departments using the National Electronic Injury Surveillance System (NEISS) database and describe the trends in the IR from 2001 to 2020. Study Design: Descriptive epidemiology study. Methods: The NEISS database was queried using injury case narratives; cases with a clear diagnosis of an acute primary tendon rupture were included in the final analysis. National estimates, estimated IRs (reported as per 1,000,000 person-years at risk), and temporal trends in the annual IR (reported as average annual percent change) of acute primary tendon ruptures were calculated using NEISS sample estimates and US Census Bureau population estimates. Results: An estimated total of 141,382 patients (95% confidence interval [CI], 107,478-175,286) presented to US emergency departments with a sports-related tendon rupture over the study period (IR, 22.9 person-years at risk [95% CI, 17.4-28.3]). The mean age was 37.7 years (95% CI, 37.0-38.5). Of all cases of a tendon rupture identified from 2001 to 2020, 60.1% were secondary to exercise/sports-related injury mechanisms. An Achilles tendon rupture was the most common injury, representing 55.9% of cases. Basketball was the most common sports-related injury mechanism, accounting for 36.6% of cases. The overall injury rate in male patients was 7.7 times that of female patients (IR ratio, 7.7 [95% CI, 4.4-13.5]; P <.05). The annual incidence of all sports-related tendon ruptures in the US increased significantly from 2001 to 2020 (average annual percent change, 1.9 [95% CI, 1.0-2.8]; P <.01). Conclusion: Recreational/competitive sports participation accounted for a large proportion of acute primary tendon ruptures in the US during the study period. [ABSTRACT FROM AUTHOR]

Background: Complex regional pain syndrome type II (CRPS-II) is a rare condition associated with peripheral nervous system lesions. Its localized distribution in the fingers is unique, and its treatment is unclear. Case Description: A 56-year-old male presented to the emergency department with a saw-cut index finger injury with associated tendon and nerve injuries. After surgery, he was admitted to physical therapy (PT) with persistent pain, joint stiffness, allodynia, and trophic changes compatible with CRPS-II localized in the index finger. The diagnosis was confirmed after applying the Budapest Criteria, and PT was progressive and individualized according to the patient's needs, including graded motor imagery, mobilizations, exercises, and education. Outcomes: After 12 weeks of PT, a clinically significant decrease in pain intensity and improvements in mobility and index finger and upper limb functionality was observed, reducing CRPS symptomatology. Discussion: This report provides information about a unique case of a localized form of CRPS-II. After reviewing the literature on clinical cases of both CRPS-II and localized forms of CRPS, we highlight that the clinical features of this patient and his positive therapeutic response support the importance of translating the scientific evidence on CRPS into clinical practice. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the prevalence of neuropathic pain in patients after surgical digital amputation. A total of 58 patients underwent digital amputation, with 30 participants providing data on 39 digits. The study found that 59% of patients experienced significant neuropathic pain at three months post-surgery. The study also assessed range of motion, grip strength, and return to work, with 24% of patients not returning to work at three months. The study highlighted the impact of neuropathic pain on patients undergoing digital amputation surgery. [Extracted from the article]

Peritendinous adhesion that forms after tendon injury substantially limits daily life. The pathology of adhesion involves inflammation and the associated proliferation. However, the current studies on this condition are lacking, previous studies reveal that cyclooxygenase‐2 (COX2) gene inhibitors have anti‐adhesion effects through reducing prostaglandin E2 (PGE2) and the proliferation of fibroblasts, are contrary to the failure in anti‐adhesion through deletion of EP4 (prostaglandin E receptor 4) gene in fibroblasts in mice of another study. In this study, single‐cell RNA sequencing analysis of human and mouse specimens are combined with eight types of conditional knockout mice and further reveal that deletion of COX2 in myeloid cells and deletion of EP4 gene in sensory nerves decrease adhesion and impair the biomechanical properties of repaired tendons. Furthermore, the COX2 inhibitor parecoxib reduces PGE2 but impairs the biomechanical properties of repaired tendons. Interestingly, PGE2 local treatment improves the biomechanical properties of the repaired tendons. These findings clarify the complex role of PGE2 in peritendinous adhesion formation (PAF) and tendon repair. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to characterize the biomechanical properties of a novel side-to-side tenorrhaphy (SST), this tenorrhaphy is designed to achieve reliable strength utilizing fewer knots and greater operationalization. This is compared with a well-established tendon reconstruction technique called the Pulvertaft weave technique (PWT). Methods: Twenty fresh porcine hindfoot flexor tendons were collected, and 10 novel SST and 10 PWT were performed in each group. The repaired tendons were tested cyclically by applying a force of 35 N using an electric tensile testing machine. Tendons were loaded until they ruptured and failed. The cyclic elongation, ultimate elongation, ultimate failure load, stiffness, and operation time were recorded and analyzed for both groups, and the failure patterns of the tendons were observed. Results: The mean operation time were 1.86 in the SST group and 3.25 min for the PWT group, respectively. The ultimate failure load was 179.93 N ± 12.05 for the SST group and 113.46 N ± 7.89 for the PWT group. The ultimate elongation was 17.79 mm ± 0.51 for the SST group and 26.83 mm ± 0.64 for the PWT group. The stiffness of the SST group was 35.27 N/mm ± 0.90 in the SST group and 20.11 N/mm ± 0.84 in the PWT group. There was no statistically significant difference in cyclic elongation. Conclusion: The SST group performed better than the PWT group in terms of the ultimate elongation, ultimate failure load, and stiffness. It is clear that the novel SST is a reliable alternative to PWT for tendon repair. The operation time of the SST group was significantly shorter than that of the PWT group. [ABSTRACT FROM AUTHOR]

AbstractObjectivesMaterials and MethodsResultsConclusions\nIMPLICATIONS FOR REHABILITATIONThis study investigated whether exercising with different relative loads would be associated with different experienced pain intensities in individuals with patellar tendinopathy.We recruited 14 individuals with patellar tendinopathy for this randomized crossover study. In a randomized order, participants performed one set of single-legged leg presses during one session with three relative loads (6 repetition maximum (RM), 10RM, and 14RM). The primary outcome was pain during exercise measured on a 0–10 Numerical Rating Scale (NRS) (0 = no pain, 10 = worst pain), which participants rated after performing the exercise set with each relative load.No differences in pain during either of the three relative loads were observed (F(2, 26) = 0.06, p = 0.942). The participants’ experienced pain was 4.5 NRS (SD1.7), 4.5 NRS (SD1.7), and 4.6 NRS (SD2.0) during the 6RM, 10RM, and 14RM loads, respectively. A secondary analysis revealed no statistically significant difference in pain intensity between the performance of the first, second, or third exercise set regardless of the load (F(2, 26) = 1.06, p = 0.367).There was no difference in pain intensity during either relative load among individuals with patellar tendinopathy. Therefore, higher loads may be applied, associated with enhanced tendon adaptation.Clinicians may tend to decrease the load if the patient suffering from patellar tendinopathy expresses pain despite no evidence supporting that reducing the load will change the pain intensity during exercise.This study found that all loads (6RM, 10RM, and 14RM) were associated with the same pain experience.Pain did not vary with different exercise loads and, therefore, should not be used as the primary guide for load selection.Clinicians may tend to decrease the load if the patient suffering from patellar tendinopathy expresses pain despite no evidence supporting that reducing the load will change the pain intensity during exercise.This study found that all loads (6RM, 10RM, and 14RM) were associated with the same pain experience.Pain did not vary with different exercise loads and, therefore, should not be used as the primary guide for load selection. [ABSTRACT FROM AUTHOR]

A tendon's ordered extracellular matrix (ECM) is essential for transmitting force but is also highly prone to injury. How tendon cells embedded within and surrounding this dense ECM orchestrate healing is not well understood. Here, we identify a specialized quiescent Scx+/Axin2+ population in mouse and human tendons that initiates healing and is a major functional contributor to repair. Axin2+ cells express stem cell markers, expand in vitro, and have multilineage differentiation potential. Following tendon injury, Axin2+-descendants infiltrate the injury site, proliferate, and differentiate into tenocytes. Transplantation assays of Axin2-labeled cells into injured tendons reveal their dual capacity to significantly proliferate and differentiate yet retain their Axin2+ identity. Specific loss of Wnt secretion in Axin2+ or Scx+ cells disrupts their ability to respond to injury, severely compromising healing. Our work highlights an unusual paradigm, wherein specialized Axin2+/Scx+ cells rely on self-regulation to maintain their identity as key organizers of tissue healing. [ABSTRACT FROM AUTHOR]

AimsMethodsResultsConclusionsObesity increases tendinopathy’s risk, but its mechanisms remain unclear. This study examined the effect of high-fat diet (HFD)-induced obesity on the outcomes and inflammation of collagenase-induced (CI) tendon injury.Mice were fed with standard chow (SC) or HFD for 12 weeks. Bacterial collagenase I or saline was injected over the patellar tendons of each mouse. At weeks 2 and 8 post-injection, the patellar tendons were harvested for histology, immunohistochemical staining, and gait analysis. The difference (Δ) of limb-idleness index (LII) at the time of post-injury and pre-injury states was calculated. Biomechanical test of tendons was also performed at week 8 post-injection.HFD aggravated CI tendon injury with an increase in vascularity and cellularity compared to SC treatment. The histopathological score (week 2: p = 0.025; week 8: p = 0.013) and ΔLII (week 2: p = 0.012; week 8: p = 0.005) were significantly higher in the HFD group compared to those in the SC group after CI tendon injury. Stiffness (saline: p = 0.003; CI: p = 0.010), ultimate stress (saline: p < 0.001; CI: p = 0.006), and Young’s modulus (saline: p = 0.017; CI: p = 0.007) were significantly lower in the HFD group compared to the SC group at week 8 after saline or collagenase injection. HFD induced higher expression of IL-1β (week 2: p = 0.010; week 8: p = 0.025) and MMP-1 (week 2: p = 0.010; week 8: p = 0.004) compared to SC treatment after CI tendon injury at both time points.HFD-induced obesity exacerbated histopathological, functional, and biomechanical changes in the CI tendon injury model, which was associated with an upregulation of IL-1β and MMP-1. [ABSTRACT FROM AUTHOR]

Background: The lateral antebrachial cutaneous nerve (LACN) is the terminal sensory branch of the musculocutaneous nerve and is rarely entrapped or injured. This study describes the electrodiagnostic (EDX) findings and etiologies of LACN neuropathy. Methods: This is a review of 49 patients with pain and/or paresthesia of the forearm who underwent EDX studies. The diagnosis of LACN neuropathy was based on clinical and sensory conduction abnormalities. Results: The most common etiology of LACN neuropathy was iatrogenic injury in 30 (61.2%) patients, primarily due to biceps tendon repair at the elbow (11 [36.7%]) and phlebotomy (5 [16.7%]). Fifteen (30.6%) patients sustained a non-iatrogenic injury at the proximal forearm/elbow, consisting of six (60%) laceration injuries and five (33.3%) stretch injuries. Four (8.2%) patients comprised the "other" etiology category, including two mass lesions causing LACN compression. Pain, paresthesia, and/or numbness in the LACN distribution were reported in 33 (67.3%), 27 (55.1%), and 23 (46.9%) patients, respectively. Hypoesthesia was detected in 45 (91.8%) patients, and dysesthesia in 7 (14.3%). The sensory nerve action potentials (SNAPs) of the LACN on the symptomatic side were absent in 44 (89.8%) patients. Of the five patients whose SNAPs of the LACN were detected, all had a decreased amplitude, and two had increased sensory latency. Conclusions: The most common etiology for LACN neuropathy in this series was iatrogenic injury; repair of biceps tendon at the elbow was the most frequent provoking cause. Protection of the LACN during surgical procedures at the elbow and forearm is vital to prevent iatrogenic injury. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Objective: Managing flexor tendon injuries surgically remains challenging due to the ongoing debate over the most effective suture technique and materials. An optimal repair must be technically feasible while providing enough strength to allow for early active mobilization during the post-operative phase. This study aimed to assess the biomechanical properties of three modified Kessler repair techniques using two different suture materials: a conventional two-strand and a modified four-strand Kirchmayr–Kessler repair using 3-0 Prolene® (2s-KK-P and 4s-KK-P respectively), and a four-strand Kessler–Tsuge repair using 4-0 FiberLoop® (4s-KT-FL). Methods: Human flexor digitorum profundus (FDP) tendons were retrieved from Thiel-embalmed prosections. For each tendon, a full-thickness cross-sectional incision was created, and the ends were reattached using either a 2s-KK-P (n = 30), a 4s-KK-P (n = 30), or a 4s-KT-FL repair (n = 30). The repaired tendons were tested using either a quasi-static (n = 45) or cyclic testing protocol (n = 45). Maximum force (Fmax), 2 mm gap force (F2mm), and primary failure modes were recorded. Results: In both quasi-static and cyclic testing groups, tendons repaired using the 4s-KT-FL approach exhibited higher Fmax and F2mm values compared to the 2s-KK-P or 4s-KK-P repairs. Fmax was significantly higher with a 4s-KK-P versus 2s-KK-P repair, but there was no significant difference in F2mm. Suture pull-out was the main failure mode for the 4s-KT-FL repair, while suture breakage was the primary failure mode in 2s- and 4s-KK-P repairs. Conclusions: FDP tendons repaired using the 4s-KT-FL approach demonstrated superior biomechanical performance compared to 2s- and 4s-KK-P repairs, suggesting that the 4s-KT-FL tendon repair could potentially reduce the risk of gapping or re-rupture during early active mobilization. [ABSTRACT FROM AUTHOR]

Background/Objectives: Rock climbing is becoming more popular, leading to an increased focus on diagnosing and treating related injuries. Finger pulley and flexor tendon injuries are common among climbers, with the A2 pulley being the most frequently affected. High-resolution ultrasound (US) is the preferred method for detecting pulley injuries. This study aimed to determine the reliability and validity of US in identifying anatomical landmarks for diagnosing A2 pulley ruptures. Methods: This study was cross-sectional, involving 36 fingers from 4 cadaver arms. A Canon Aplio i800 US machine was used to measure two anatomical landmarks: the midpoint of the proximal phalanx and the distal edge of the A2 pulley. For the first anatomical landmark, the length of the proximal phalanx (PP distance), and for the second landmark, the distance between the distal edges of the proximal phalanx and the A2 pulley ("A" distance), were measured. Measurements were performed by two sonographers and compared to a digital caliper measurement taken post-cadaver dissection. Observers were blinded during measurements to ensure unbiased results. Results: Overall PP distance measured by US (O1: 37.5 ± 5.3 mm, O2: 37.8 ± 5.4 mm) tended to be shorter than caliper measurements (O3: 39.5 ± 5.5 mm). The differences between sonographers were minimal, but larger when compared to caliper measurements. High reliability for PP distance measurement was observed, especially between sonographers, with an ICC average of 0.99 (0.98, 1.00). However, reliability was lower for the "A" distance, with significant differences between US and caliper measurements. Regarding validity, US measurements were valid when compared to caliper measurements for PP distance, but not as reliable for the "A" due to wider confidence intervals. While US can substitute caliper measurements for PP distance (LR, Y:O2, X:O3, −0.70 (−3.28–1.38), 0.98 (0.93 ± 1.04)), its validity for "A" distance is lower (LR, Y:O2, X:O3, −2.37 (−13.53–4.83), 1.02 (0.62–1.75)). Conclusions: US is a reliable and valid tool in identifying anatomical landmarks for diagnosing A2 pulley ruptures, particularly for detecting the midpoint of the proximal phalanx. This is important to differentiate between complete and partial A2 pulley tears. However, the measurement of the "A" distance requires further refinement. These findings support efforts to standardize US examination protocols and promote consensus in diagnostic methodology, though further research is needed to address the remaining challenges. [ABSTRACT FROM AUTHOR]

Tendons play fundamental roles in the execution of human movement and therefore understanding tendon function, health and disease is important for everyday living and sports performance. The acute mechanical behavioural and physiological responses to short-term loading of tendons, as well as more chronic morphological and mechanical adaptations to longer term loading, differ between sexes. This has led some researchers to speculate that there may be a sex-specific injury risk in tendons. However, the link between anatomical, physiological and biomechanical sex-specific differences in tendons and their contributory role in the development of tendon disease injuries has not been critically evaluated. This review outlines the evidence surrounding the sex-specific physiological and biomechanical responses and adaptations to loading and discusses how this evidence compares to clinical evidence on tendon injuries and rehabilitation in the Achilles and patellar tendons in humans. Using the evidence available in both sports science and medicine, this may provide a more holistic understanding to improve our ability to enhance human tendon health and performance in both sexes. [ABSTRACT FROM AUTHOR]

Background: WALANT has gained much popularity in recent years, especially with COVID-19. However, a recent survey of the American Society for Surgery of the Hand membership (i.e. attendings/consultants) showed that only 17% were exposed to WALANT during residency or fellowship training. There is much interest in WALANT from trainees, but interpretation of the type and volume to be administered is highly varied. Methods: The aims of this study were (1) to survey a group of plastic surgery trainees in the UK about their knowledge of WALANT formulas, and (2) to compare trainee logbook records of WALANT procedures (if available) with published data from the UK. Results: All trainees were familiar with the 'standard' WALANT formula (1% lidocaine, 1:100,000 adrenaline ± 8.4% NaHCO3) described by Lalonde. However, because of local formularies, rather than 1:100,000 adrenaline, all used 1:200,000 adrenaline as it comes premixed in the UK. Other formulas used by UK trainees included 0.5% bupivacaine + 1:200,000 adrenaline, and mixing 1% lidocaine + 1:200,000 adrenaline with 1% lidocaine 1:1. In comparing available trainee WALANT records with published UK data, the average volume of WALANT used was 6.6 mls in the current study versus 12.9 mls for similar procedures (wound debridement and skin closure ± local flap, digital nerve repair, fingertip reconstruction, thenar injuries, phalangeal fracture and single digit extensor repair); specifically, for single digit flexor tendon repairs, this was 10 mls versus 16.3 mls. Conclusions: While the British Society for Surgery of the Hand (BSSH) have developed official guidance for the use of WALANT in the UK, it appears there remains much variation in interpretation and hence, application. Comparison of trainee logbook records of common hand surgery procedures suggests that most can be done with much less WALANT administered than previously reported, with safe and reproducible results. Level of Evidence: Level IV (Therapeutic) [ABSTRACT FROM AUTHOR]

Background: Extensor tendon injuries require surgical repair, followed by rehabilitation to ensure optimal outcomes. Immobilization has been the cornerstone of postoperative management. However, immobilization after surgery frequently makes the finger stiffness, often resulting in reduced functionality and quality of life for patients. Recent studies indicate that early controlled motion can significantly improve outcomes, but safe early range of motion (ROM) exercise is a significant clinical challenge. This article aims to check the efficacy of the novel designed finger ROM brace for preventing finger stiffness for extensor tendon injuries with case series. Methods: A finger ROM brace was designed based on the natural finger movement. Like a real finger, there are two tiny hinge joints and three round-shape body components. The design aimed to be ergonomic dynamic splint assisting controlled motion to promote early motion, thus reducing tendon tension and preventing stiffness. Elastic resistant ROM exercise could be by inserting a silicone band into the groove on the components and free movement could be achieved by removing a silicone band. Result: Between December 2022 and July 2023, 10 patients who underwent tenorrhaphy because of extensor tendon laceration were involved. Complete extensor tendon laceration was 3 patients, other seven patients had partial laceration of extensor tendons. Surgery was performed within 2 days of injury, and no infection was observed in all patients. After the extensor tendon was confirmed as healed state by ultrasound, the patients were permit the active exercise wearing finger ROM brace with a silicone band. Within 1–2 weeks after elastic resistant exercise, the patients could achieve free full ROM movement without any complication. Conclusion: The novel finger ROM brace combines the advantages of dynamic splinting and under-actuated mechanisms to offer a comprehensive solution for preventing stiffness after extensor tendon suture. Future studies should focus on clinical trials to validate the efficacy and safety of this brace in a larger population. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to evaluate the functional outcome and quality of life in distal biceps tendon repair with single incision technique and anchor fixation method. Methods: A retrospective cohort study was made of patients with complete distal biceps tendon rupture. The chosen repair method was single incision technique with anchor fixation. The outcome was assessed with functional testing of the elbow with strength and ROM. Additionally Mayo elbow performance index, Oxford elbow score, Disability arm hand shoulder questionnaire and patient rated elbow evaluation scores were used to evaluate quality of life. Results: Of the 28 patients, the average strength in flexion and supination was decreased with 91% and 89% of the strength compared to the non-injured arm. ROM was preserved in flexion, extension, supination and pronation. The mean scores for quality of life evaluation were MEPS = 96 ± 7.8, OES = 46.8 ± 1.9, DASH = 1.0 ± 1.9 and PREE = 2.0 ± 3.6. LABCN injury was the most common temporary complication with 30% followed by pain with 23%. Two patients were identified with HO and 1 patient was identified with median nerve injury. There were no cases of radioulnar synostosis and PIN injury. Conclusion: Overall strength in flexion and supination were slightly decreased with preserved ROM. Patients reported nearly perfect quality of life as demonstrated with the scores. The complications rate was high with mainly minor complications. Distal biceps tendon repair with single incision technique and anchor fixation overall leads to a very satisfying outcome. [ABSTRACT FROM AUTHOR]

Purpose: Quadriceps tendon disruption post-total knee arthroplasty (TKA) is rare. Existing reconstruction procedures use allografts or synthetic meshes with varied success. This study evaluates outcomes with autogenous peroneal tendon grafts, a cost-effective alternative, compared to synthetic polypropylene mesh for quadriceps reconstruction. Methods: 16 patients who underwent extensor mechanism reconstruction between 2017 and 2021were retrospectively analysed. Parameters evaluated included type of reconstruction, extensor lag, IKDC (International Knee Documentation Committee) Score and AOFAS-Hindfoot-score (American Orthopaedic Foot and Ankle Society). Results: At final follow-up, extensor lag for peroneal autograft group was 6.6° ± 1.5 and for synthetic polypropylene mesh group, 7.2° ± 0.7. Both groups improved in IKDC score (p < 0.01) AOFAS-Hindfoot-score was comparable for peroneal autograft patients with opposite side (p = 0.15). Conclusions: Autogenous peroneal tendon graft for quadriceps reconstruction could be viable, cost-effective alternative to allografts or synthetic meshes, with good clinical outcomes. Graphical abstract depicting the harvesting of the peronei grafts and their passage through the quadriceps tendon. Sonographic image showing the preoperative presence of a gap in the quadriceps tendon which is reconstructed post-operatively [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate whether there is a difference in hand bone mineral density (BMD) between patients with traumatic hand injuries and healthy volunteers during the immobilization process, as well as to examine the change in BMD during follow‑up and the effect of denervation on BMD. In addition, we aimed to compare the BMD in the dominant and nondominant hands. Methods: The study involved patients aged 18–55 years who had undergone surgery for hand tendon injuries (TIs), with or without accompanying nerve injury, and subsequently sought rehabilitation at our outpatient clinic. The study groups were comprised patients with TI, those with tendon and nerve injury (TNI), and healthy volunteers. Results: The study examined 24 patients with TI, 23 with TNI, and 31 healthy volunteers. In the healthy control group, the BMD of the dominant hand was significantly higher than that of the nondominant hand (P < 0.001). At 4 weeks, there was no significant decrease in BMD observed in the TI and TNI groups compared to controls (P > 0.05). However, at the 4th month, both groups showed a significant decrease in BMD, with the TNI group exhibiting higher changes (P < 0.05). Injuries to the dominant hand did not result in significant changes in BMD at 4 weeks and 4 months (P > 0.05). However, a significant decrease in BMD was observed in injuries to the nondominant hand compared to controls at 4 months (P < 0.05). Notably, nondominant hand TNI patients experienced a significant reduction in BMD during the 4th month compared to the 4th week (P < 0.05). In addition, a significant correlation (r = 0.567) was found between grip strength and BMD value in the 4th month of patients with hand injuries. Conclusion: In patients with traumatic hand injuries, nondominant hand injury and/or nerve injury may lead to a decrease in BMD in addition to immobilization. [ABSTRACT FROM AUTHOR]

Background: Surgical repair of full thickness biceps tears has demonstrated adequate outcomes in short and mid-term studies. However, data on the long-term outcomes of full thickness distal biceps injuries and their treatment are currently lacking. Purpose/Hypothesis: The purpose of this study was to report on patient demographics, injury characteristics, and long-term outcomes for patients with full-thickness distal biceps tears. It was hypothesized that complete distal biceps tears managed operatively would demonstrate robust clinical success at long-term follow-up. Study Design: Case series; Level of evidence, 4. Methods: Patients with magnetic resonance imaging–confirmed, complete distal biceps tendon rupture sustained between 1996 and 2016 were identified. Patients were cross-referenced with a regional geographic database. Results: A total of 66 patients (3 female, 63 male) with a median age of 50.8 years (IQR, 41.5-60.4) and a median clinical follow-up of 14.7 years (IQR, 9.6-17.9 years) were included. Patients who sustained a full-thickness distal biceps tendon tear were likely to be in their early 50s, male, right-hand dominant, current/former smokers, and laborers with a history of traumatic injury during an intentional movement. Most of these patients had pain and supination weakness but no loss of range of motion. All included tears were treated operatively. At final follow-up, patients maintained a majority of near-normal range of motion (median total arc of flexion/extension 140° and supination/pronation 80°), excellent elbow flexion strength (91% of patients had full strength), and adequate elbow supination strength (76% of patients had full strength). The overall complication rate was 24%, with 16 out of 66 patients experiencing some type of complication between infection, rerupture, heterotopic ossification, reoperation, and nerve complications. Overall return to work was 98%, and 85% of those who returned to work did so without restrictions. Conclusion: Complete tears of the distal biceps were most common in patients 50 years of age, male sex, right-hand dominant, and current/former smokers. The most common profession was laborer, and injuries were primarily traumatic in nature during intentional activity. Patients managed operatively demonstrated high rates of success at long-term follow-up with respect to elbow function and clinical outcomes. [ABSTRACT FROM AUTHOR]

Background: Restoring shoulder strength after arthroscopic rotator cuff repair (ARCR) is critical, but there is limited understanding as to what patients consider satisfactory postoperative strength. Purpose: To determine the Patient Acceptable Symptom State (PASS) values for the Constant score strength parameter and internal rotation (IR) strength in patients who underwent ARCR for rotator cuff tears involving the subscapularis (SSC) muscle and evaluate for associations between preoperative and intraoperative patient characteristics with PASS achievement. Study Design: Case-control study; Level of evidence, 3. Methods: A retrospective analysis was conducted on prospectively collected data for 278 patients with an SSC tear (isolated or combined) who underwent ARCR and had minimum 2-year follow-up data. Functional outcomes (patient-reported outcomes, range of motion, Constant strength, and IR strength) were assessed preoperatively and at the latest follow-up. The overall, male, and female PASS values for postoperative strength measures were evaluated using receiver operating characteristic analysis. Correlation and logistic regression analyses were used to evaluate the relationship between preoperative variables and PASS achievement for Constant and IR strengths. Results: The mean follow-up time was 72.8 months. The overall, male, and female PASS values were 9.9 lb (4.5 kg), 14.5 lb (6.6 kg), and 8.5 lb (3.9 kg), respectively, for Constant strength and 15.2 lb (6.9 kg), 20.7 lb (9.4 kg), and 12.1 lb (5.5 kg), respectively, for IR strength. Older age, high fatty infiltration of the SSC tendon (Goutallier grades 3 and 4), and failure of SSC healing correlated negatively with PASS attainment for the strength measures. High fatty infiltration of the supraspinatus and infraspinatus muscles correlated negatively with Constant strength. Decreased coracohumeral distance (CHD) and larger SSC tears correlated negatively with achieving PASS for IR strength. Workers' compensation, high supraspinatus and SSC fatty infiltration, and the use of knotted suture anchors were predictors of not achieving the overall Constant strength PASS, while lower SSC fatty infiltration and high CHD were predictors of achieving the overall IR strength PASS. Conclusion: This study established the PASS values for Constant and IR strengths for patients after ARCR involving the SSC tendon. Workers' compensation, high supraspinatus and SSC fatty infiltration, and the use of knotted suture anchors were predictors of not achieving the overall Constant strength PASS, while lower SSC fatty infiltration and high CHD were predictors of achieving the overall IR strength PASS. [ABSTRACT FROM AUTHOR]

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Background and Objectives: Complex wounds in the hand and distal lower extremities pose challenges in reconstructive surgery, often involving critical structures like tendons. Tendon injuries, prevalent in such wounds, necessitate optimal repair methods for functional recovery. This study investigates the impact of vascularised and nonvascularised adipofascial tissue on tendon repair, focusing on early healing stages, mobilisation, and scintigraphic evaluation of flap vascularity. Materials and Methods: Wistar Albino rats were divided into groups undergoing primary tendon repair, vascularised adipofascial flap application, or nonvascularised flap application. Scintigraphic evaluation and histopathological assessment were performed to analyse healing processes. Results: Pedicle-free flaps support healing in tendon injuries without negatively affecting medium-term outcomes. Vascularised flaps exhibit faster healing. The scintigraphic analysis showed that the static measurements of the late phase were statistically significantly higher in the group with the non-vascularised adipofascial flap (p = 0.038). The mean perfusion reserve was higher in the vascularised pedicled adipofascial flap group than the non-vascularised adipofascial flap group. Scintigraphic analysis highlights the viability of pedicle-free flaps. Conclusions: Pedicle-free adipofascial flaps support the healing of the tendon without complicating the results, while vascularised flaps show accelerated healing. These findings provide valuable insights into optimising tendon repair strategies using adipofascial flaps, with implications for enhancing functional recovery in complex wounds. [ABSTRACT FROM AUTHOR]

Heterotopic ossification (HO) is a pathological process that commonly arises following severe polytrauma, characterized by the anomalous differentiation of mesenchymal progenitor cells and resulting in the formation of ectopic bone in non-skeletal tissues. This abnormal bone growth contributes to pain and reduced mobility, especially when adjacent to a joint. Our prior observations suggested an essential role of NGF (Nerve Growth Factor)-responsive TrkA (Tropomyosin Receptor Kinase A)-expressing peripheral nerves in regulating abnormal osteochondral differentiation following tendon injury. Here, we utilized a recently developed mouse model of hip arthroplasty-induced HO to further validate the role of peripheral nerve regulation of traumatic HO. Nerve ingrowth was either modulated using a knockin transgenic animals with point mutation in TrkA, or local treatment with an FDA-approved formulation of long acting Bupivacaine which prevents peripheral nerve growth. Results demonstrate exuberant sensory and sympathetic nerve growth within the peri-articular HO site, and that both methods to reduce local innervation significantly reduced heterotopic bone formation. TrkA inhibition led to a 34% reduction in bone volume, while bupivacaine treatment resulted in a 50% decrease. Mechanistically, alterations in TGFβ and FGF signaling activation accompanied both methods of local denervation, and a shift in macrophages from M1 to M2 phenotypes was observed. In sum, these studies reinforce the observations that peripheral nerves play a role in the etiopathogenesis of HO, and that targeting local nerves represents a potential therapeutic approach for disease prevention. [ABSTRACT FROM AUTHOR]

Tendon injury is a common motor system disease, impairing joint mobility, and lowering quality of life. Once damaged, tendon has a limited capacity for regeneration. Clinically, available therapeutic strategies have not achieved satisfactory outcomes. Chiral biomaterials can effectively regulate cell behaviors and tissue healing, but have not been applied to injured tendon yet. Here, chiral arginine is attached to electrospun membrane to fabricate chiral scaffolds. L‐chiral scaffold, rather than D‐chiral or R‐chiral scaffold, promotes cell adhesion, proliferation, and tenogenic differentiation. The vinculin/FAK/YAP pathway is discovered to have a significant impact on the processes mentioned above. Additionally, L‐arginine efficiently eliminates reactive oxygen species (ROS) and generates nitric oxide (NO), safeguarding tendon stem/progenitor cells (TSPCs) against oxidative stress. The use of L‐chiral scaffold in a rat model of Achilles tendon injury increases the expression of markers related to tendons and the deposition of collagen. Moreover, L‐chiral scaffold improves tendon structural, functional, and mechanical properties. This L‐chiral scaffold comprehensively enhances tendon healing, providing a promising therapeutic strategy for tendon injury. As a simple and effective method, modification by chiral molecules enriches biomaterial functions and offers a novel option for tissue regeneration. [ABSTRACT FROM AUTHOR]

Simple Summary: The description of health patterns of eventing horses outside of veterinary clinics is limited. It is important to determine the relative impact of different health problems in this group of horses. The study aimed to describe the prevalence and patterns of lameness/illness in registered British eventing horses in 2018 by use of an online survey. Data were collated and descriptive analyses undertaken. In total, 1677 surveys were completed, and 49.4% reported a previous lameness/musculoskeletal problem, with 26% in the previous six months. The most frequently reported musculoskeletal problems were to the foot (421), joints (382), wounds (340), back (333), ligament (205), tendon (213), bones (140) and muscles (135). The most frequent non-musculoskeletal problems were to the skin (183), gastric ulceration (173), colic (145) and infection (88). Injuries to the sole of the foot/muscles/tendons were most frequently sustained in competition, suspensory ligament/splint bone/stifle/hock injuries were more frequently sustained in training and foot abscesses/penetration injuries at rest. Horses with deep digital flexor tendon injuries were out of training for the most amount of time (>12 months) and horses with hock/sole bruising/foot abscesses for the least amount of time (<2 weeks). A greater understanding of health problems in eventing horses could be useful for veterinarians working with them. There has been little investigation into the health patterns of the eventing horse population outside veterinary clinics. To target health problems in the eventing horse population, it is important to determine the relative impact of different health problems. The objectives were to describe the prevalence and patterns of lameness/illness in registered British eventing horses. An online survey was released for all horses registered with British eventing in 2018. Data were collated and descriptive analyses undertaken. A total of 1677 surveys were completed, among which 49.4% reported a previous lameness/musculoskeletal problem, 26% being in the previous six months. The most frequently reported musculoskeletal problems were in the foot (421), joints (382), wounds (340), back (333), ligament (205), tendon (213), bones (140) and muscles (135). The most frequent non-musculoskeletal problems related to the skin (183), gastric ulceration (173), colic (145) and infection (88). Injuries to the hoof sole/muscles/tendons were most frequently sustained in competition, suspensory ligament/splint bone/stifle/tarsal injuries were more frequently sustained in training and abscess/foot penetration at rest. DDFT injuries were most frequently out of training for >12 months, SDFT/stifle/suspensory ligament for <12 months, tendon sheath/splint bone for <3 months and tarsal/sole bruising/abscess for <2 weeks. A greater understanding of injuries/illnesses frequently sustained could be useful for veterinarians working with event horses. [ABSTRACT FROM AUTHOR]

In the last two decades, ultrasound has been fully implemented in the diagnosis and management of rheumatoid arthritis. Several studies have been published that have demonstrated better availability of this technique in the identification of elementary inflammatory joint and tendon injuries, as joint and tendon sheath synovial hypertrophy, joint effusion, and Power Doppler signal. Ultrasonography has good properties to identify changes with different treatments, have predictive value for relapse in patients in clinical remission and in structural damage. Furthermore, ultrasound tools have been developed that allow prospective evaluation of patients. Joint and tendon ultrasound evaluation indexes have been used for disease diagnosis and monitoring. Initially, indexes have been integrated only for joint, but more recently have appeared mixed indexes, integrated for ultrasound evaluation and other types of variables. There are still important objectives to be achieved to complete the development of ultrasound in rheumatoid arthritis, which makes ultrasound a great aid tool in decision-making in clinical practice. [ABSTRACT FROM AUTHOR]

The technology of 3D bioprinting has sparked interest in improving tendon repair and regeneration, promoting quality of life. To perform this procedure, surgical intervention is often necessary to restore functional capacity. In this way, 3D bioprinting offers a scaffold design, producing tendons with precise microarchitectures, promoting the growth of new tissues. Furthermore, it may incorporate bioactive compounds that can further stimulate repair. This review elucidates how 3D bioprinting holds promise for tendon repair and regeneration, detailing the steps involved and the various approaches employed. They demonstrate future challenges and perspectives and provide valuable information on the concept, bioprinting design, and 3D bioprinting techniques for the repair of tendon injuries. [ABSTRACT FROM AUTHOR]

Hamstring strain injuries (HSIs) are prevalent in sports involving high-speed running and most of the HSIs are biceps femoris long head (BFlh) injuries. The primary cause for HSIs during high-speed running remains controversial due to the lack of in vivo measurement of the BFlh muscle behavior during running. Therefore, the purpose of this study was to quantify the muscle-tendon unit (MTU) and fascicle behavior of BFlh during running. Seven college male sprinters (22.14 ± 1.8 years; 177.7 ± 2.5 cm; 70.57 ± 5.1 kg; personal bests in 100m: 11.1 ± 0.2 s) were tested on a motorized treadmill instrumented with two force plate for running at 4, 5, 6m/s. The ground reaction force (GRF), 3D lower limb kinematics, EMG, and ultrasound images of biceps femoris long head (BFlh) in the middle region were recorded simultaneously. BFlh fascicles undergo little length change (about 1 cm) in the late swing phase during running at three submaximal speeds. BFlh fascicle lengthening accounted for about 30% of MTU length change during the late swing phase. BFlh was most active during the late swing and early stance phases, ranging from 83% MVC at a running speed of 4 m/s to 116% MVC at 6 m/s. Muscle fascicles in the middle region of BF1h undergo relatively little lengthening relative to the MTU in the late swing phase during running in comparison to results from simulation studies. These results suggest that there is a decoupling between the fascicle in the middle region and MTU length changes during the late swing phase of running. [ABSTRACT FROM AUTHOR]

Introduction: Flexor tendon injuries are common and require surgery. Acellular dermal matrix (ADM) is a natural graft used to repair tissues, though infections represent the primary cause of its therapeutic failure. In this study, zinc oxide nanoparticles (ZnO-NPs) were coated on the ADM in order to add antibacterial potential as well as enhance healing properties. Also, the produced ADM/ZnO-NPs graft was applied to accelerate fifth zone flexor tendon repair following the reconstructive surgery. Methods: Morphological, mechanical, cell viability, and antibacterial tests were performed to evaluate the physical and biological properties of the fabricated ADM/ZnO-NPs graft. For clinical evaluations, 20 patients with a flexor tendon injury in zone 5 were randomly divided into control and treatment with ADM/ZnO-NPs groups (n=10 each). The control group had routine reconstructive surgery, while the other group received the ADM/ZnO- NPs graft during their surgery. Postoperative functional outcomes were evaluated 4, 6, and 8 weeks following the tendon repair surgery according to the Buck-Gramcko II criteria. Results: The ADM/ZnO-NPs had natural derm specifications as well as dense and integrated morphology with intermediate antibacterial properties. According to the Buck-Gramcko II criteria, the postoperative functional outcome scores were significantly higher in the ADM/ZnONPs group in comparison with the control group at 4 (P<0.01), 6 (P<0.01), and 8 (P<0.001) weeks after the surgery. Conclusion: The present findings revealed that the ADM/ZnO-NPs graft can accelerate the healing of the damaged tendon without common post-operative functional complications and adhesions following the tendon repair surgery. However, more comprehensive clinical trials are still needed. [ABSTRACT FROM AUTHOR]