Tendon Structure Research Articles

Effect of Diabetes on Tendon Structure and Function: Not Limited to Collagen Crosslinking.

Diabetes mellitus (DM) is associated with musculoskeletal complications-including tendon dysfunction and injury. Patients with DM show altered foot and ankle mechanics that have been attributed to tendon dysfunction as well as impaired recovery post-tendon injury. Despite the problem of DM-related tendon complications, treatment guidelines specific to this population of individuals are lacking. DM impairs tendon structure, function, and healing capacity in tendons throughout the body, but the Achilles tendon is of particular concern and most studied in the diabetic foot. At macroscopic levels, asymptomatic, diabetic Achilles tendons may show morphological abnormalities such as thickening, collagen disorganization, and/or calcific changes at the tendon enthesis. At smaller length scales, DM affects collagen sliding and discrete plasticity due to glycation of collagen. However, how these alterations translate to mechanical deficits observed at larger length scales is an area of continued investigation. In addition to dysfunction of the extracellular matrix, tendon cells such as tenocytes and tendon stem/progenitor cells show significant abnormalities in proliferation, apoptosis, and remodeling capacity in the presence of hyperglycemia and advanced glycation end-products, thus contributing to the disruption of tendon homeostasis and healing. Improving our understanding of the effects of DM on tendons-from molecular pathways to patients-will progress toward targeted therapies in this group at high risk of foot and ankle morbidity.

Tendon microstructural disruption promotes tendon-derived stem cells to express chondrogenic genes by activating endoplasmic reticulum stress.

The erroneous differentiation of tendon-derived stem cells (TDSCs) into adipocytes, chondrocytes, and osteoblasts is believed to play an important role in the development of tendinopathy. However, the regulatory mechanisms of TDSC differentiation remain unclear. The aim of this study is to investigate the contribution and mechanism of the tendon microstructural disruption to the differentiation of TDSCs. Bovine Achilles tendons were sliced. The tendon slices were stretched with different tensile strains to mimic the tendon structure alteration at various scales. The TDSCs were cultured on the tendon slices. The differentiation of TDSCs and endoplasmic reticulum (ER) stress in the TDSCs were investigated with quantitative reverse transcription polymerase chain reaction, immunostaining and western blot. The effect of ER stress inhibition on chondrogenic differentiation of the TDSCs was further investigated. The structural alteration did not affect the viability of TDSCs. However, the structural alteration of tendon slices with 6.4% strain promoted TDSCs to express the chondrogenic genes. ER stress-related markers, ATF-4 and PERK, were also upregulated. With the inhibition of ER stress, the expression of ATF-4 and the chondrogenic gene SOX9 of TDSCs were inhibited. The study indicated that tendon microdamage could induce the chondrogenic differentiation of TDSCs through triggering ER stress to activate ATF-4 and SOX9 subsequently.

Photobiomodulation for Tendinopathy: A Review of Preclinical Studies.

The outcomes of clinical studies utilizing Photobiomodulation on tendon disorders are not homogeneous and since its design depends on preclinical studies utilizing animal models as a prerequisite, this review investigates the literature to help extrapolate preclinical evidence-based outcomes (safety and efficacy) into clinical treatment options. PubMed and Embase databases were searched for tendinopathy, Photobiomodulation and preclinical studies with inclusion criteria were restricted to in vivo animal studies using rat's models subjected to partially injured tendons. Data extracted were methodology quality and design, light parameters, study methods, and outcomes. Twenty two articles were included, half of them were partially transected, while the other half were partially traumatized. The most common wavelengths used were 660, 830, and 904 nm with energy density range between 1 and 17 J/cm2 and applied mostly daily. Fourteen studies (64%) relied merely on a single assessment. Histological measurements were the most common method of evaluation (75%) and 35% of studies used chemical measures. Mechanical outcomes were reported in four, and two studies demonstrate significant effects. Photobiomodulation has the potential to enhance tendon structure and function, however, inevitable embedded heterogeneity related to study design and quality of methods, light parameters delivered, and evaluations methods renders the ability to establish unified treatment parameters difficult. Adjustments for variability within preclinical studies might lead to better designing of clinical studies. It is recommended to embrace a protocol for designing and performing preclinical studies to improve its quality. Moreover, it is recommended to prove efficacy using at least two evaluation methods and apply Photobiomodulation as a combined varying energy/wavelength protocol (several energies with several wavelengths). Clinical relevance: Establishing a proof of concept for Photobiomodulation that may lead to further high-quality clinical studies, in which the applicable parameters can be determined.

Histology of tendon and enthesis - suitable techniques for specific research questions.

The musculoskeletal system consists of different components comprising a wide range of tissue types, with tendons being one part. Tendon degeneration or rupture have a high prevalence in all age groups, often with poor outcomes of surgical treatment such as chronic pain and high re-tear rates. Therefore, much effort has been directed to further develop diagnostic and therapeutic methods as well as reconstruction techniques, including using adequate placeholders or implants. Diagnostic approaches and advanced stages of preclinical studies will inevitably include histological examination of the pathologically affected tissue. The present study presents adequate tendon-related, histological techniques, including the embedding of soft- and hard-tissue samples in different media. Consideration is also given to samples containing residual implant materials or having been subjected to standard staining protocols and immunohistochemical procedures. The study further examines cells and tendon structure to detect degenerative, fibrotic or inflammatory conditions and possible foreign-body responses to implanted materials. Infraspinatus tendons from preclinical studies carried on rat and sheep samples, as well as human biceps tendon samples, have been used as example materials.

Tendon loading in runners with Achilles tendinopathy: Relations to pain, structure, and function during return-to-sport.

We aimed to (1) compare pain, tendon structure, lower limb function, and Achilles tendon loads while running between limbs in runners with Achilles tendinopathy, and (2) explore the relations of pain, tendon structure, and lower limb function to Achilles tendon loads while running. Twenty runners with Achilles tendinopathy participated in this pilot study. Pain was assessed with questionnaires, quantitative sensory testing, and functional testing. Tendon morphology and mechanical properties were evaluated with ultrasound imaging, continuous shear wave elastography, and ultrasound imaging combined with dynamometry. Lower limb function was assessed with an established test battery. Achilles tendon loads were estimated from biomechanical data acquired during running. Compared to the least symptomatic limb, the most symptomatic limb had lower scores on the Victorian Institute of Sports Assessment - Achilles questionnaire and worse pain during drop countermovement jumping, hopping, and running. Tendon thickness and cross-sectional area were greater, and Young's modulus, drop countermovement jump height, and plyometric quotient during hopping were lower on the most symptomatic limb. Side-to-side differences in drop countermovement jump height were significantly associated with side-to-side differences in Achilles tendon peak forces and average loading rates during running. Various measures of pain, structure, and function differ between limbs in runners with Achilles tendinopathy during return-to-sport. Tendon forces, however, do not differ between limbs during comfortable running. In addition to measures that differ between limbs, measures of performance during drop countermovement jumping may aid in clinical decision-making during return-to-sport because they are associated with tendon forces while running.

Quantitative shear wave elastography compared to standard ultrasound (qualitative B-mode grayscale sonography and quantitative power Doppler) for evaluation of achillotendinopathy in treatment-naïve individuals: A cross-sectional study.

Achillotendinopathy is reported as an overuse disorder and/or degeneration change of the tendon. The diagnosis of tendinopathy is not always easy through imaging modalities. The B-mode grayscale sonography and power Doppler are well-established methods aimed at visualising tendon structure, but have limited sensitivity and lack conventional sonographic characteristics in symptomatic patients. Shear wave ultrasound elastography quantitatively assesses tissue stiffness. To compare the diagnostic accuracy of shear wave ultrasound elastography to that of standard ultrasound (combined B-mode grayscale sonography and power Doppler) for diagnosis of achillotendinopathy, considering clinical symptoms as the reference standard. Standard questionnaires regarding medical history and the Chinese version of a Victorian Institute of Sports Assessment - Achilles Questionnaires (VISA-AC) score were evaluated for a total of 14 treatment-naïve patients with complaints of localized swelling, and reduced force and/or flexibility of the Achilles tendon(s). The irregular thickening around the Achilles tendon, heterogeneity of echotexture of the tendon and calcification of the calcaneal attachment were considered incidences of tendinopathy in B-mode grayscale sonography. Tendinopathies were considered if tendons were >0.60 cm thick in power Doppler. Shear wave elasticity <350 kpa (10 m/s) was considered tendinopathy. A total of 28 conditions of both sides were evaluated through standard ultrasound examinations. Eighty-four tendons were assessed using shear wave ultrasound elastography. Asymptomatic tendons were visible as red and symptomatic (VISA-AC score <80) tendons were visible as blue or turquoise in the images. The rigidity of symptomatic tendons was lower than that of asymptomatic tendons (p < 0.0001). Sensitivity and accuracy for standard ultrasound were increased by the addition of shear wave ultrasound elastography for both symptomatic and asymptomatic tendons. The VISA-AC score was strongly correlated with the elasticity values (p = 0.000, Kendall's tau-beta (τβ) = 0.71) of Achilles tendons. Shear wave ultrasound elastography augments diagnostic confidence of standard ultrasound for the treatment of tendinopathies of Achilles tendons.

An Especially Unique Case of Accessory Flexor Muscles to All Five Digits with Clinical Implications for Occupational Therapy

INTRODUCTIONAnatomical variations in antebrachial musculature are relatively common. Most are asymptomatic, but some develop serious sequelae. Extra tendon structures in the carpal tunnel can cause carpal tunnel syndrome (CTS), accessory muscle attachments can cause symptomatic supernumerary muscle belly (SSMB) syndrome, and compression of the anterior interosseus nerve from overlaying supernumerary muscles can cause anterior interosseus nerve syndrome (AINS). Many studies have reported accessory muscles to the flexor pollicis longus (aFPL) or flexor digitorum profundus (aFDP), but few have examined co‐occurrences of these muscles, and none have documented a case where they collectively send isolated flexion forces to all five digits. The objective of this study is to analyze an especially unique case of accessory flexor muscles to all five digits with respect to CTS, SSMB syndrome, and AINS clinical implications for Occupational Therapy (OT).METHODSOne aFPL and four aFDPs were found co‐occurring during routine cadaver dissection at the University of Nebraska Medical Center. All neurovascular and muscular components within the flexor compartment of the antebrachium were carefully cleaned of extraneous fascia. Contiguous muscles were reflected to view the muscle bellies, tendons, proximal attachments (origins), and distal attachments (insertions) of the aFPL and aFDPs. The aFPL and aFDPs were measured and photographed in situ, and maximal isometric force (Fmax) was calculated for each muscle. The normal FPL and FDP were also analyzed to gauge accessory muscle impact. A review of relevant literature was conducted to discuss clinical implications of these muscles for OT practice.RESULTSA bicipital accessory muscle to FDP, with radial (aFDPr) and ulnar (aFDPu) heads, was discovered adjacent to an accessory muscle to FPL (aFPL). The aFDPr/u and aFPL originated from the coronoid process of the ulna and were innervated by the posterior‐lying anterior interosseus nerve. The aFDPr flexed digits 3 and 4, and aFDPu flexed digits 4 and 5. The aFPL was especially unique: part of its tendon merged with the proximal third of FPL (to flex digit 1) while the remainder continued distal, drawing two additional distinct muscle bellies from FPL (aFDPFPL) and FDP (aFDPFDP) and distributing these adjoining forces to digits 2, 3, and 4 via an aponeurosis in the carpal tunnel. The calculated Fmax for aFPL, aFDPr, aFDPu, aFDPFPL, and aFDPFDP were 3.80 N, 1.22 N, 0.98 N, 2.47 N, and 0.62 N respectively and are used to discuss potentials for eliciting a quadriga effect associated with SSMB syndrome. CTS is discussed as a result of carpal tunnel crowding, and AINS is discussed in regard to neuropathy of FDP (radial half), FPL, and pronator quadratus. Each of these conditions is conferred with their predominant implications for OT intervention and treatment.CONCLUSIONS &amp; SIGNIFICANCEThe present study reports a previously undocumented and especially unique case of accessory flexor muscles to all five digits. Its use as a reference may help OT providers better determine when supernumerary muscles are present in clients being treated for prehension, distal pinch, and digit independence limitations caused by CTS, SSMB syndrome, or AINS and adapt treatment modalities accordingly.

Tendon and Ligament Genetics: How Do They Contribute to Disease and Injury? A Narrative Review.

A significant proportion of patients requiring musculoskeletal management present with tendon and ligament pathology. Our understanding of the intrinsic and extrinsic mechanisms that lead to such disabilities is increasing. However, the complexity underpinning these interactive multifactorial elements is still not fully characterised. Evidence highlighting the genetic components, either reducing or increasing susceptibility to injury, is increasing. This review examines the present understanding of the role genetic variations contribute to tendon and ligament injury risk. It examines the different elements of tendon and ligament structure and considers our knowledge of genetic influence on form, function, ability to withstand load, and undertake repair or regeneration. The role of epigenetic factors in modifying gene expression in these structures is also explored. It considers the challenges to interpreting present knowledge, the requirements, and likely pathways for future research, and whether such information has reached the point of clinical utility.

A prospective observational study on the beneficial effects and tolerability of a cetylated fatty acids (CFA) complex in a patch formulation for shoulder tendon disorders

BackgroundThe advancement of physiopathological knowledge of tendon structures has shown that, in conditions of overload, there is the onset of both degenerative phenomena, such as the production of metalloproteases, apoptosis of tendon cells and neoangiogenesis, and regenerative and protective phenomena, such as the production of IGF-1 and nitric oxide. Tendinopathy results from the imbalance between these two groups of factors, leading to degeneration, weakening, and fissuring of the tendons, with the presence of local pain. The aim of the study was to evaluate the efficacy and tolerability of cetylated fatty acids (CFA) patch formulation in the control of acute localized shoulder pain and recovery of function in patients with tendinopathies.MethodsA prospective, single-center, no-profit observational study conducted in accordance with Good Clinical Practice. Thirty patients with recent onset shoulder pain symptoms (1–3 months) related to bursitis and tenosynovitis, with a diagnosis of shoulder tendon pathology confirmed by ultrasound examination, was evaluated for shoulder pain and function using the Constant Murley Score. Patients used 1 patch containing CFA for 8 h per day for 10 days. At 10 (V1) and 35 (V2) days after the first visit (V0), the Constant Score, treatment compliance and product tolerability were evaluated.ResultsThirty patients completed the treatment. At V0 the mean Constant Score (CS) was 32.37 ± 11.86, during V1 the mean CS was 50.68 ± 14.30, and at V3 the mean CS was 51.07 ± 15.29. The CS increased significantly between V0 and V1 (p < 0.0001) but did not vary significantly between V1 and V2 (p = 1). The tolerability of the product was excellent.ConclusionsApplication of the CFA-based patch for 10 consecutive days in patients with shoulder tendinopathies was effective in reducing local pain and resulted in a good recovery of function. The results achieved at day 10 were maintained for 25 days, until the follow-up visit at day 35. CFA-based patch, thanks to their efficacy and tolerability, seems to be a promising solution to improve pain and functionality in subject with shoulder tendinopathy.Trial registrationThe study was approved by the Ethics Committee of Azienda USL Toscana Nord Ovest (protocol code 2018RIAB105) and conducted in accordance with Good Clinical Practice and the ethical principles outlined in the Declaration of Helsinki.

Differences and regularities of the macro- and microscopic structure of the limb tendons

The aim of the study was to present differences and regularities in the macro- and microscopic structure of the muscle tendons of the limbs identified by comparative analysis and generalization of the obtained findings.Material and methods. The study included transverse histotopograms of 519 tendons of 17 different muscles of the upper and lower limbs. Histotopograms were received from 93 human cadavers and amputated limbs of 10 patients. Transverse sections of tendons up to 20 μm thick were stained with picrofuchsin according to Van Gieson, and hematoxylin–eosin. Histotopograms were studied and photographed using a stereoscopic microscope MBS-10.Results. The authors have generalized data on the macro- and microscopic structure of the limb tendons. General regularities of the internal macro- and microscopic structure of the tendons have been specified. It has been demonstrated that these regularities are of applied relevance for improvement of restorative tendon microsurgery. Individual differences and differences between the tendons of different muscles at the structural level were revealed: the number, size, architectonics of the tendon bundles of the 1st order. Tendon bundles of the 1st order are the main structural units of the macro- and microscopic structure of the limb muscle tendons. Depending on the size of the cross-sectional area, they can be divided into small (0.004–0.009 mm2), medium (0.01–0.04 mm2), large (0.05–0.09 mm2) and very large (0.1–0.5 mm2). There were detected differences in the number, ratio and architectonics of the tendon bundles at different levels within one tendon; this allows assuming division and fusion of tendon bundles of the 1st order throughout the tendon.Conclusion. The macro- and microscopic structure of the muscle tendons of the upper and lower limbs demonstrates general regularities and differences in the structure of the various muscle tendons, the fact being of theoretical and applied significance.

600 Reconstruction of Finger Contracture with an Expanded Dorsal Metacarpal Artery Perforator Flap

IntroductionThe first dorsal metacarpal artery perforator (DMCAP) flap is frequently used to cover exposed bone, tendon and neurovascular structures in the hand after trauma and burns. The size and width of DMCAP flap is limited and rotation arc generally lets to cover defects up to middle phalanx. Expansion of the DMCAP flap has not been reported in the literature and this technique might be solution to increase flap viability and size in order to cover defects up to distal phalanx. In this study, we will describe utilization of tissue expander to first DMCAP and present a case of electric burns in with flexor contracture.MethodsA nine-year-old male patient applied to our clinic with the complaint of inability to extend the second finger of the left hand after an electrical burn. Physical examination revealed flexor contracture in the distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints. Reconstruction was planned for the patient with a two-session expanded first DMCAP flap.In the first session, a 16 cc 5x3 cm tissue expander placed through a 3 cm vertical incision at the fifth metacarpal level. From the second postoperative week, the tissue expander was inflated with 1 ml of isotonic three days a week. Six weeks later, the DMCAP area was enlarged by giving 45 cc saline.ResultsIn the second session, contractures at the level of the left hand 2nd finger DIP and PIP were excised.. Left hand 2nd finger was fixated in extension with K-wire. 9x3 cm DMCAP flap was elevated by dissection over the paratenon and the pedicle was preserved. The flap was adapted to the defect area on the volar face with 180-degree rotation angle. The flap donor site was closed primarily.There were no complications in the post-operative period. K-wire was removed at 6 weeks postoperatively. The patient was referred to the physical therapy.ConclusionsIn cases where the tissue defect cannot be closed with loco regional flaps, extra tissue can be provided by free flaps or using tissue expanders. Primary closure of the donor area, appropriate flap thickness for the finger, and aesthetically pleasing results are among the advantages of the expanded DMCA flap.. However, in tissue expander applications in the upper extremity, the patient should be followed closely, and pain and finger circulation should be constantly questioned.

Biglycan has a major role in maintenance of mature tendon mechanics.

Decorin and biglycan are two small leucine-rich proteoglycans (SLRPs) that regulate collagen fibrillogenesis and extracellular matrix assembly in tendon. The objective of this study was to determine the individual roles of these molecules in maintaining the structural and mechanical properties of tendon during homeostasis in mature mice. We hypothesized that knockdown of decorin in mature tendons would result in detrimental changes to tendon structure and mechanics while knockdown of biglycan would have a minor effect on these parameters. To achieve this objective, we created tamoxifen-inducible mouse knockdown models targeting decorin or biglycan inactivation. This enables the evaluation of the roles of these SLRPs in mature tendon without the abnormal tendon development caused by conventional knockout models. Contrary to our hypothesis, knockdown of decorin resulted in minor alterations to tendon structure and no changes to mechanics while knockdown of biglycan resulted in broad changes to tendon structure and mechanics. Specifically, knockdown of biglycan resulted in reduced insertion modulus, maximum stress, dynamic modulus, stress relaxation, and increased collagen fiber realignment during loading. Knockdown of decorin and biglycan produced similar changes to tendon microstructure by increasing the collagen fibril diameter relative to wild-type controls. Biglycan knockdown also decreased the cell nuclear aspect ratio, indicating a more spindle-like nuclear shape. Overall, the extensive changes to tendon structure and mechanics after knockdown of biglycan, but not decorin, provides evidence that biglycan plays a major role in the maintenance of tendon structure and mechanics in mature mice during homeostasis.

Neuromuscular disorders in women and men with spinal cord injury are associated with changes in muscle and tendon architecture

Objective The present study aimed to determine the association between neuromuscular function, motor function impairment, and muscle and tendon structures in individuals with spinal cord injury (SCI) compared to a control (non-disabled) population. Design A cross-sectional study with a control group. Setting Center of Adapted Sports Training and Special Physical Education. Participants Fifteen individuals with SCI and motor function impairments participated in the study. A paired non-disabled group was recruited for comparison. Interventions Not applicable. Outcome measures Muscle (biceps brachii, rectus femoris, vastus lateralis, vastus medialis, and tibialis anterior) and tendon (quadriceps and patellar tendons) structures were assessed by ultrasound imaging (thickness, pennation angle, fascicle length, and echogenicity). Neuromuscular electrophysiological disorders were also assessed using electrodiagnosis techniques (stimulus non-responsivity and chronaxie) in the same muscles. Results Except for the biceps brachii muscle, muscle thickness, pennation angle, and fascicle length were lower (p < 0.01) while echogenicity and chronaxie were greater (p < 0.01) in SCI participants. The SCI participants had a higher prevalence of neuromuscular electrophysiological disorders for all muscles, except the biceps brachii. Conclusion Neuromuscular disorders occur in association with muscle and tendon maladaptation in individuals with chronic SCI. A higher prevalence of electrophysiological disorders suggests an acquired polyneuromyopathy for muscles with motor function impairment even though the muscle was innerved, in addition to widespread muscle atrophy.

Ultrasound-guided, minimally invasive looped thread fasciotomy for chronic exertional compartment syndrome of the lower leg: A cadaveric feasibility study

Background– Chronic exertional compartment syndrome (CECS) is an exertional pain syndrome that typically affects the lower legs of participants involved in high-intensity running or marching activities. Surgical open fasciotomy is the standard treatment for recalcitrant cases of CECS. Alternative, minimally invasive fasciotomy techniques are emerging which may reduce rates of procedural complications and expedite recovery. The standard fasciotomy procedure for CECS may be improved by looped thread release with additional image guidance. The aim of this study was to describe and evaluate a novel technique of ultrasound-guided, minimally invasive looped thread fasciotomy for release of anterior and lateral compartments of the leg in a cadaveric model. We hypothesized that a fasciotomy of this type would be effective in achieving a target fasciotomy length of 80% of the length of a muscle compartment while avoiding injury to neurovascular structures. Materials and methods– We conducted a controlled laboratory study. Two proceduralists performed anterior and lateral compartment fasciotomies on ten lightly embalmed cadaveric legs. A total of twenty compartment releases were completed, using an ultrasound-guided, percutaneous looped cutting thread technique. The specimens were evaluated for length and completeness of fasciotomy, as well as any inadvertent injury to muscle, tendon, or neurovascular structures. Completeness of fasciotomy was compared between the anterior and lateral compartments. Results– Eighteen of twenty (90%) fasciotomies were continuous. Fasciotomy length was consistently under target (72% complete). Completeness of lateral compartment release was significantly more likely to be under target compared to anterior compartment release (65% vs. 79%, p ​= ​0.014). Sixteen of twenty (80%) fasciotomies incurred no iatrogenic soft tissue injury; no injuries to nerves or vessels were observed. Discussion –Ultrasound-guided, minimally invasive looped thread fasciotomy of the anterior and lateral leg compartments is feasible and can be successfully performed in a cadaveric model with low risk to neurovascular structures. However, further investigation is needed to improve completeness of release prior to recommendation for clinical use.

A Case of Chronic Deep Infrapatellar Bursitis Complicated by Patellar Tendinopathy and its Evaluation With Musculoskeletal Ultrasound

Knee pain is a very common complaint in routine physiatry and orthopedic practice. While bursitis is a well-known and common cause of knee pain, deep infrapatellar bursa (DIPB) involvement is relatively less common. Inflammation of DIPB occurs commonly due to either direct trauma or overuse, but other rare causes have also been reported in the literature including infection, juvenile idiopathic arthritis, gout, and juvenile ankylosing spondylitis. We report a case of chronic inflammation of DIPB caused by direct trauma and associated with patellar tendinopathy. Additionally, we describe the characteristic findings on musculoskeletal ultrasonography (MSK-USG). For ultrasound evaluation, the patient should lie supine with the knee slightly flexed. Deep infrapatellar bursitis can be seen as an anechoic fluid-filled structure immediately posterior to the distal patellar tendon and anterior to the tibial tuberosity. While MRI can confirm the diagnosis of bursitis, MSK-USG can be quick, highly sensitive, and is able to confirm the diagnosis as well as to detect dynamic changes in the patellar tendon and adjacent structures. USG can also help in the treatment by guiding corticosteroid injection into the bursa. Activity modification and eccentric exercises play an important role in the rehabilitation program in these cases.

Characterize the microstructure change after tendon enthesis injury using synchrotron radiation μCT.

The microstructure of the bone-tendon interface (BTI) deserves in-depth investigation. In this study, we first aimed to extend the application of synchrotron radiation μCT to characterize the gradient structure of supraspinatus tendon (SST) enthesis, from both tissue morphology to cell distribution. Second, to acquire detailed morphological information of SST enthesis when after injury. Our results showed that in normal enthesis, the phenotype of chondrocyte in BTI was dependent on its distance to subchondral bone. After injury, the fibrocartilage cells were disrupted, as evidenced by reduced lacunae size. Our observation may partly explain the loss of BTI mechanical properties after injury, and we believe the application of synchrotron radiation microcomputed tomography will have promising potential for characterizing the morphology changes in enthesis and for evaluating the therapeutic effects of interventions in preclinical studies.

Achilles Tendon and Patellar Tendon Structure in Combat Soldiers Following Prevention Exercises.

Military training that increases physical stress on musculoskeletal morphology also increases the risk of orthopedic injuries. Somatosensory prevention programs that reduce stress and improve functionality could be beneficial for better organization of tendon structure. The aim of this study was to investigate the impact of a somatosensory prevention exercise on the tendon structure (percentage of echo-type fibers; A-P and M-L diameters and cross-sectional area) of the Achilles tendon and patellar tendon among combat soldiers. These tendons of male Infantry soldiers aged 18-21 were screened before and after a 14-week training course. The intervention group, who performed preventative exercises, included 108 soldiers (BMI = 23.85 ± 2.76), while the control group, who participated in the same military course without these exercises, included 98 soldiers (BMI = 24.26 ± 4.03). Ultrasound scanning for tendon structure included percent of echo-type I-IV fibers, A-P diameter, M-L diameter, and cross-sectional area parameters. Time by group interaction was found for echo-type I and II in both tendons. No significant differences were found between the two groups in the pretesting percentage of echo-type IV fibers of the Achilles tendon (P = .522), in echo-type III fibers of the Achilles tendon (P = .833), and echo-type IV fibers of the patellar tendon (P = .162). Greater pre-post differences in echo-type III and IV fibers were found in the control group compared with the intervention group for both the Achilles tendon (P = .021, P = .002) and the patellar tendon (P < .001, P < .001). Increased damaged fibers (echo-type III and IV) of both tendons were found among the control group, yet not among soldiers who performed prevention exercises.

Mechanical properties of muscles and tendon structures in middle-aged and young men

The purpose of this study was to compare the mechanical properties of muscles and tendon structures for plantar flexor muscles at various strain rates and jump performances using single joint between middle-aged and young men in order to clarify the mechanisms of age-related decline in power output during vertical jump of middle-aged people previously reported. Passive muscle stiffness of the medial gastrocnemius muscle was determined based on passive muscle force and fascicle length during passive stretching at four angular velocities. Active muscle stiffness was calculated based on changes in muscle force and fascicle length during stretching at five angular velocities after submaximal isometric contractions. Maximal elongation and hysteresis of tendon structures were assessed from estimated muscle force—tendon elongation during ramp and ballistic contractions. Two kinds of unilateral jump heights using only ankle joint (no-countermovement and countermovement jumps) were measured. No significant differences in passive and active muscle stiffness, tendon structure properties (except for maximal elongation during ramp contraction), or jump heights were found between middle-aged and young men. The results suggest that the mechanical properties of muscles and tendon structures for plantar flexor muscles and jump performances using only ankle joint do not show age-related changes in middle-aged men.

Femoral Orthopedic Implants in Dogs with Titanium - Mechanical Evaluation

ABSTRACTBackground: Orthopedic implants are commonly used for different types of surgical procedures to gain optimal function and to provide stability to both bones and tendon structures. When inserting these implants, the characteristics of the material are important for surgical success, and the ideal implant must be biocompatible and nonallergenic. However, when molding an implant to the bone structure, its resistance can change significantly. Implants can be temporary or permanent in the body, and metal possesses properties that make it acceptable for bone repair. In biomedical implants, 2 types are most common, commercially pure (CP)-Ti and Ti-6A1-4V. They both provide stable fixation and low risk of loosening. Implants made with the same material and composition can perform differently if the material has been altered by processing techniques for different scenarios. Stress, strain and elastic modulus are the primary metrics used in the description of implant materials. They can be calculated based on mechanical tests of specimens with defined geometry, most commonly tensile, bending and torsional tests. In order to better evaluate those changes, we compared the mechanical characteristics of titanium bone plates, before and after they were molded to the bone, to verify and quantify the loss of stiffness and resistance after molding the plate.Materials, Methods &amp; Results: The study was prospective. Orthopedic implant made of commercially pure titanium (CP-Ti) were divided into 2 groups, one group without plate molding and the other with plate molding to a dog femora bone. Thirty-six plates of different sizes (5.0, 6.5, 8.0, 9.0, 10.0 and 11.0-mm diameter) were divided into 6 groups containing 6 plates of each size and submitted to the 4-point flexion test of resistance, using a piece of dog femur (weights of 5, 10, 15, 20 and 25 kg) as the bone in which the molding was performed. The evaluations were tabulated and analyzed using the program GraphPad Prism version 5.0. Corrections of the normal distribution curve were made using the Bartlett test. After the corrections, one-way analysis of variance (ANOVA) was performed with P &lt; 0.05. Assessments were made within the group and between groups. Subsequently, the Newman-Keuls test was performed, adopting P &lt; 0.05. For analyses in 2 groups, Student's t-test was performed as a post-test, also with P &lt; 0.05. When the plates were compared between equal sizes of groups 1 and 2, the non-molded plate group (G1) obtained the best results in the flexural stiffness and structural flexion tests. However, in the flexural resistance test, most plates obtained similar results and the plates with diameters of 8 mm, 9 mm and 10 mm of the molded plate group (G2) obtained the best results.Discussion: Our results show that the implants had adequate mechanical characteristics, but the unmolded plates had greater flexural and structural stiffness than the molded plates. This difference was significant, thus demonstrating a large loss of stiffness in relation to the original conformation. However, when we tested the flexural resistance, no significant differences were observed, and although without significant statistical changes, there was an increase in the resistance of the plate with the new conformation obtained by molding. In the results of the mechanical tests, we observed that after the molding, the implants gained greater resistance, although the difference was not statistically significant. This suggests that the architecture of the implants should have slight curvature in the medial direction of the bone, since this would lead to a better adaptation to the anatomy of the bone, and possibly greater resistance, as indicated by the new configuration after molding.Keywords: bone implants, titanium, orthopedic implants, femur, dogs.

Relationships between tendon structure and clinical impairments in patients with patellar tendinopathy.

The clinical relevance of altered tendon structure in patellar tendinopathy is contested since structural change persists after symptom resolution. The purpose of this study was to explore the relationships between tendon structure and clinical impairments in patellar tendinopathy. In this retrospective, secondary analysis of individuals with patellar tendinopathy (n = 41), tendon structure (thickness, cross-sectional area [CSA], shear modulus, and viscosity), symptom severity, lower extremity function (counter-movement jump [CMJ] height), and quadriceps muscle performance (knee extension force and central activation ratio [CAR]) were recorded for the symptomatic limb. Relationships among structure, symptom severity, lower extremity function, and quadriceps muscle performance were examined using sequential regression models. Adjusting for age, sex, body mass index, and pain levels, there were significant positive relationships for thickness (p < 0.001, β = 0.718) and viscosity (p = 0.006, β = 0.496) with CMJ height. There were significant negative relationships between CSA with both CMJ height (p = 0.001, β = -0.538) and CAR (p = 0.04, β = -0.517). This is the first study to demonstrate relationships between tendon structure and lower extremity function or quadriceps muscle performance in patients with patellar tendinopathy. Clinical significance: Since structural changes persist after symptom resolution, addressing these changes may assist in restoring lower extremity function and quadriceps muscle performance.