Osteotendinous Junction Research Articles

Arthroscopic evaluation of the rotator cuff vasculature: inferences into the pathogenesis of cuff tear and re-tear.

Little is known about alterations of the rotator cuff (RC) macroscopic vasculature associated with medical conditions and/or habits that predispose a person to diseases of the peripheral microcirculation. The high frequency of cuff tear and re-tear in patients with diabetes, hypercholesterolemia, uncontrolled arterial hypertension, or metabolic syndrome may be due to tissue hypovascularity. The macroscopic vasculature of both the articular and bursal sides of the posterosuperior RC was evaluated arthroscopically in 107 patients (mean age, 58.2 years) with no RC tear. Patients were divided into three groups according to medical comorbidities and lifestyle factors (group I, none; group II, smokers and/or drinkers and one comorbidity; and group III, two or more comorbidities). Pulsating vessels originating from both the myotendinous and osteotendinous junctions were assessed as "clearly evident," "poorly evident," or "not evident." Groups I, II, and III comprised 36, 45, and 26 patients, respectively. Within the myotendinous junction, vessels were visualized in 22 group I patients (61%), 25 group II patients (55%), and 6 group III patients (23%) (P=0.007). Pulsating arterial vessels originating from the osteotendinous junction were seen in 42%, 36%, and 0% of patients, respectively (P<0.001). Within the bursal side of the RC, a dense anastomotic network was visualized (either clearly or poorly) in 94% (34), 80% (36), and 35% (9) of patients, respectively (P<0.001). The macroscopic vasculature of the RC is influenced by pre-existing diseases and lifestyle factors, which may impair peripheral microcirculation. Level of evidence: III.

Melt Electrowriting Combined with Fused Deposition Modeling Printing for the Fabrication of Three-Dimensional Biomimetic Scaffolds for Osteotendinous Junction Regeneration.

This study aims to explore a novel scaffold for osteotendinous junction regeneration and to preliminarily verify its osteogenic and tenogenic abilities in vitro. A polycaprolactone (PCL) scaffold with aligned and orthogonal fibers was created using melt electrowriting (MEW) and fused deposition modeling (FDM). The scaffold was coated with Type I collagen, and hydroxyapatite was carefully added to separate the regions intended for bone and tendon regeneration, before being rolled into a cylindrical shape. Human adipose-derived stem cells (hADSCs) were seeded to evaluate viability and differentiation. Scaffold characterization was performed with Scanning Electron Microscope (SEM). Osteogenesis was assessed by alkaline phosphatase (ALP) and Alizarin red staining, while immunostaining and transcription-quantitative polymerase chain reaction (RT-qPCR) evaluated osteogenic and tendogenic markers. Scaffolds were developed in four variations: aligned (A), collagen-coated aligned (A+C), orthogonal (O), and mineral-coated orthogonal (O+M). SEM analysis confirmed surface morphology and energy-dispersive X-ray spectroscopy (EDS) verified mineral coating on O+M types. Hydrophilicity and mechanical properties were optimized in modified scaffolds, with A+C showing increased tensile strength and O+M improved in compression. hADSCs demonstrated good viability and morphology across scaffolds, withO+M scaffolds showing higher cell proliferation and osteogenic potential, and A and A+C scaffolds supporting tenogenic differentiation. This study confirms the potential of a novel PCL scaffold with distinct regions for osteogenic and tenogenic differentiation, supporting the regeneration of osteotendinous junctions in vitro.

Release of TGF-β3 from Surface-Modified PCL Fiber Mats Triggers a Dose-Dependent Chondrogenic Differentiation of Human Mesenchymal Stromal Cells.

The design of implants for tissue transitions remains a major scientific challenge. This is due to gradients in characteristics that need to be restored. The rotator cuff in the shoulder, with its direct osteo-tendinous junction (enthesis), is a prime example of such a transition. Our approach towards an optimized implant for entheses is based on electrospun fiber mats of poly(ε-caprolactone) (PCL) as biodegradable scaffold material, loaded with biologically active factors. Chitosan/tripolyphosphate (CS/TPP) nanoparticles were used to load transforming growth factor-β3 (TGF-β3) with increasing loading concentrations for the regeneration of the cartilage zone within direct entheses. Release experiments were performed, and the concentration of TGF-β3 in the release medium was determined by ELISA. Chondrogenic differentiation of human mesenchymal stromal cells (MSCs) was analyzed in the presence of released TGF-β3. The amount of released TGF-β3 increased with the use of higher loading concentrations. This correlated with larger cell pellets and an increase in chondrogenic marker genes (SOX9, COL2A1, COMP). These data were further supported by an increase in the glycosaminoglycan (GAG)-to-DNA ratio of the cell pellets. The results demonstrate an increase in the total release of TGF-β3 by loading higher concentrations to the implant, which led to the desired biological effect.

Immediate effects of isometric versus isotonic exercise on pain sensitivity and motor performance of ankle plantiflexor muscles

This study aimed to quantify the differences on pain sensitivity and motor performance ankle plantiflexor muscles after performing an isometric versus an isotonic exercise task. A parallel experimental trial was carried out at the European University of the Canary Islands. A total of 47 healthy volunteers were recruited and randomly assigned to a group receiving an isometric exercise (n = 23) and a group receiving an isotonic exercise (n = 24). Pain threshold to pressure was measured at four specific points of the triceps surae neurosensory territory in medial gastrocnemius, lateral gastrocnemius, Tendo Achilles osteotendinous unit and aponeurosis plantar insertion. Furthermore, the two-point discriminatory threshold of the osteotendinous junction of the Achilles tendon and maximum voluntary contraction for plantar flexion were assessed before and after the intervention. There were no statistically significant intergroup differences for any of the variables PPT-MG (U Mann Whitney = 25; [1.265-0.650], p = .527), PPT-LG (U Mann Whitney = 25; [1.325-0.945]; p = .527) y PPT-TA (U Mann Whitney = 25; [-1.465-0.405] p = .527), D2P (U Mann Whitney = 30.5, IC95% [-0.800-1.300], p = .630) and MVC-PF (U Mann Whitney = 26.5, IC95% [-8.400, 2.900], p = .386). Isometric exercise was the only one able to modify the PPT-AP before and after treatment in a statistically significant way. In contrast, isotonic exercise was the training that demonstrated clinically significant changes in 2PD and MVC-PF before and after treatment. No statistically significant changes were identified between both groups in any of the variables studied.

Enhancement of in vivo supraspinatus tendon–to-bone healing with an alginate-chitin scaffold and rhBMP-2

IntroductionRotator cuff disorders present a high retear rate despite advances in surgical treatment. Tissue engineering could therefore be interesting in order to try to enhance a more biological repair. RhBMP-2 is one of the most osteogenic growth factors and it also induces the formation of collagen type I. However, it has a short half-life and in order to get a more stable release over time it could be integrated in a more slowly degradable carrier, such as an alginate-chitin scaffold. The aim of this study was to investigate the role of the alginate-chitin scaffold alone and in combination with different concentrations of rhBMP-2 when applied on chronic rotator cuff lesions in a rat model. Materials and MethodsWe performed an experimental study with 80 Sprague-Dawley rats, 8 months old, with a chronic rupture of the supraspinatus tendon that was repaired with a modified Mason Allen suture. A scaffold was applied over the suture and 4 groups were obtained; suture (S) only suture, double control (DC) alginate and chitin scaffold, single sample (SS) scaffold of alginate with rhBMP-2 (20 µg rhBMP-2) and chitin, double sample (DS) a scaffold containing alginate with rhBMP-2 and chitin with rhBMP-2 (40 µg rhBMP-2). Macroscopic, histological and biomechanical studies were performed at 4 months after reparation. ResultsThe modified Åström and Rausing's histological scale (the higher the score the worse outcome, 0 points=native tendon) was applied: S got 52 points compared to DC 30 (p = 0,034), SS 22 (p = 0,009) and DS 16 (p = 0,010). Biomechanically the maximum load was highest in DC (63,05 N), followed by DS (61,60 N), SS (52,35 N) and S (51,08), p = 0,025 DS vs S. As to the elastic constant a higher value was obtained in DC (16,65), DS (12,55) and SS (12,20) compared to S (9,33), p = 0,009 DC vs S and 0,034 DS vs S. ConclusionsThe alginate-chitin scaffold seems to promote a more biological response after the reparation of a chronic rotator cuff lesion. Its effect is further enhanced by the addition of rhBMP-2 since the osteotendinous junction is more native-like and has better biomechanical properties.

Information on medicinal uses of chuchuhuasi (Maytenus macrocarpa) from folk healers of the district of Santa María de Huachipa, Lurigancho, Lima - Peru: a qualitative study

Objective: To inquire the main conditions, properties and ways of consumption of chuchuhuasi from a group of folk healers of the district of Santa María de Huachipa (Lima – Peru). There are studies of the medicinal uses of chuchuhuasi (Maytenus macrocarpa) in native communities of the Amazon known by the inhabitants and indicated by folk healers. However, information on the medicinal uses and properties of chuchuhuasi on the coast and in urban communities is rare. Materials and methods: Ten folk healers voluntarily participated in the study. An interview questionnaire was administered to inquire the use of chuchuhuasi (properties, adverse effects, contraindications and ways of consumption). The interview was recorded and then transcribed. Afterwards, the data was categorized by peers and defined by consensus. Results: The main conditions for consuming chuchuhuasi were respiratory tract (80 %) and osteotendinous junction problems. The most important properties of chuchuhuasi were its anti-inflammatory and aphrodisiac effects. Dizziness was reported as adverse effect. Chuchuhuasi was contraindicated in pregnancy, hypertension and diabetes. In addition, its main ways of consumption were as spirit, ointment and infusion. Conclusions: Information on the medicinal uses of chuchuhuasi was obtained from a group of folk healers of the district of Santa María de Huachipa (Lima – Peru). The main condition for consuming chuchuhuasi was respiratory tract problems, and its antiinflammatory properties were highlighted.

Comparison of the effects of hyperbaric oxygen and extracorporeal shock wave therapy on healing in osteotendinousjunctional injuries: an experimental study of the rabbit model

Objectives: To biomechanically and histopathologically compare the effects on healing in the osteotendinous region of the treatment methods of hyperbaric oxygen (HBO) and extracorporel shock wave (ESW) on an injury created at the osteotendinous junction in an experimental rabbit model. Methods: The study included 36 New Zealand rabbits.The patellar tendon tibial osteotendinous junction was cut and then repaired. Group 1 was evaluated as the control group, with no further intervention.In Group 2, a single session of ESW was applied at 14 hz/750 Impulse/10 mins to an area 1×1 cm2 in the repaired area under fluoroscopy guidance. The animals in Group 3 were applied with 100% oxygen as HBO at 2.4 ATA/110 min for 7 days. At the end of 6 weeks, 6 animals from each group were applied with a tension test and 6 animals were processed for histopathological examination. Results: In Group 1, the forces at the start of the separation of the osteotendinous junction, at a 2 mm separation and at full rupture were lower than those of Group 2 and Group 3 (p = 0.001 and p = 0.001, respectively). The highest separation force values were determined in Group 3 (p = 0.001). Histopathologically, a statistically significant difference was determined in respect of the fibrocartilage tisssue formation, and fusion with new bone tissue between Group 1 and Group 2 and between Group 1 and Group 3 (p &amp;lt; 0.05). No statistically significant difference was determined between Group 2 and Group 3 (p = 0.310). Conclusions: It was observed that the application of HBO and ESW improved biomechanical resistance and healing in the injuries in the osteotendinous junction by increasing the bone-tendon fusion in this area.The application of HBO and ESW increased biomechanical resistance compared to the control group.In the histopathological evaluation, the ESW group was better than the control group and the HBO group was evaluated as the best.

Ultrasound Measurements of the ECRB Tendon Shows Remarkable Variations in Patients with Lateral Epicondylitis.

Lateral epicondylitis (LE) most commonly affects the Extensor Carpi Radialis Brevis (ECRB) tendon and patients are generally treated with injection therapy. For optimal positioning of the injection, as well as an estimation of the surface area and content of the ECRB tendon to determine the volume of the injectable needed, it is important to know the exact location of the ECRB in relation to the skin as well as the variation in tendon length and location. The aim of this study was to determine the variation in location and size of the ECRB tendon in patients with LE. An observational sonographic evaluation of the ECRB tendon was performed in 40 patients with LE. The length of the ECRB tendon, distance from the cutis to the center of the ECRB tendon, the length of the osteotendinous junction at the epicondyle and the distance from cutis to middle of the osteotendinous junction were measured. The average tendon length was 1.68cm (range 1.27-1.98; SD 0.177). Compared to women, the ECRB tendon of men was on average 0.12cm longer. Overall, the average distance from cutis to the center of the ECRB was 0.75cm (range 0.50-1.46cm; SD 0.210), the average length of the junction was 0.55cm (range 0.35-0.87; SD 0.130), and the distance from cutis to middle of the osteotendinous junction was 0.73cm (range 0.40-1.25cm; SD 0.210). The size and depth of the ECRB tendon in patients with LE is largely variable. While there are no studies yet suggesting sono-guided injection to be superior to that of blind injection, the anatomic variability of this study suggests that the accuracy of injection therapy for LE might be compromised when based solely on bony landmarks and therefore not fully reliable. As a result, there is value in further studies exploring the accuracy of the ultrasound guided injection techniques.

The Effect of Pentoxifylline and Hyperbaric Oxygen on Achilles Osteotendinous Junction İnjury: An experimental animal model study.

To investigate the effects of hyperbaric oxygen (HBO) and pentoxifylline (PTX) treatment on osteotendinous junction healing of Achilles tendon in an animal model. Thirty-six adult female Wistar-albino rats were randomly divided into three groups as control, PTX and HBO groups with a total of 12 rats per group. Under general anesthesia, the Achilles tendons were cut at the level of the osteotendinous junction and repaired. After the surgery, no treatment was given to the control group. Fifty mg/kg intraperitoneal PTX was administered to the PTX group daily for 1 week. The HBO group was exposed to 2,5 atmospheric pressure, 100% oxygen for 2 hours daily for 1 week. All animals were sacrificed at the end of sixth week. Biomechanical tests and histological examinations were performed. Energy absorption was significantly higher in the PTX group than that in the control group after biomechanical tests (p=0.010). Histopathological evaluation results revealed no difference between the groups: however, hyalinization level was relatively better in the HBO group than that in the control group (p=0.026). 1. We concluded that PTX has a positive effect on the treatment of osteotendinous junction injuries based on our results. 2. Although HBO therapy did not provide statistically significant differences, it might have some positive effects on these injuries. 3. Further experimental studies and clinical trials should be conducted.

Histopathological changes in patellar tendon enthesis of rabbit induced by electrical stimulation intensity

BackgroundEnthesis injury is a common problem in athletes and workers, which is considered closely related to overuse. However, the early pathophysiologic changes of osteotendinous junction are not well understood, and moreover, few studies investigated the relationship between intensity and pathological changes. The purpose of this study was to evaluate microstructural changes induced by different loading intensities and to find out the threshold intensity. MethodsForty-eight New Zealand White rabbits were randomly divided into six groups. One control group, the others were electrically stimulated to contract repetitively for 2 h per day, three days a week. 30% of peak tetanic force (7.06 N) was adopted to stimulate the rabbits in the 100% cyclic loading group. Other groups were stimulated with 20%, 40%, 60% and 80% of this force. After four weeks, prepared samples were stained with hematoxylin and eosin. ResultsAfter 4 weeks of cyclic loading, the shape and the distribution of tendon cells in patellar enthesis changed, the arrangement of collagen fibers became disordered and the tidemark had become irregular or even disappeared. Different stimulus intensity caused a significant change of cell density in different groups (F = 10.19, P < 0.001). The cell densities of tendon were 34.3 ± 7.9 cells/100 μm2 (L60), 38.2 ± 5.9 cells/100 μm2 (L80), 43.8 ± 10.3 cells/100 μm2 (L100) respectively, which had significant difference with CON group 22.5 ± 3.5 cells/100 μm2. The thickness of fibrocartilage zone had no significant difference among the groups. ConclusionsThe changes of histomorphology with the increasing exercise intensity elucidated that the degree of enthesis microdamage was directly related to the intensity of exercises. The findings demonstrated that 18% (used in L60 group) of peak tetanic force was the threshold intensity which could induce pathological changes in enthesis in four weeks.

Using Biotensegrity to Explain the Mechanically‐Induced Lesions in Navicular Disease

Degenerative joint disease (DJD), the most common disease affecting humans and animals, has long been believed to result from failure of the joints from ‘wear and tear’ in which damage exceeds repair. However, models that depict the body as a machine do not adequately explain the functional musculoskeletal anatomy, in particular the role of fascia, nor do they explain why the lesions of DJD do not always correlate with pain and dysfunction. In contrast a body structured through tensegrity (integrity by tension; biotensegrity) has a seamless integration of structure and function from the molecular, cellular, tissue and organ levels to the whole body, and better explains how life evolved by adapting to different environments. Joints structured through tensegrity have more functional flexibility as tensegrity allows mechanical forces to be transmitted and dispersed throughout the surrounding connective tissues and counteracted by muscular contractions rather than being transmitted as compression across a joint space, which is the case in machine models. The purpose of this study was to use biotensegrity to explain the pathogenesis of tissue damage in navicular disease, a devastating form of DJD in horses. The structure of the navicular apparatus indicates it is an enthesis organ that functions through tensegrity to dissipate forces away from the osteotendinous junction between the deep digital flexor tendon and the distal phalanx. Functional analyses of 3D models reconstructed from CT scans of a horse's forelimb were used to predict where mechanical forces were most impacting the navicular enthesis organ. These models show that pronounced dorsiflexion of the foot, a posture commonly observed in horses with navicular disease, increased the mechanical forces on the deep digital flexor tendon, navicular bone, impar and collateral sesamoidean ligaments, which are all sites of tissue damage in navicular disease. Histochemical staining with Masson's trichrome and picrosirius red, confirmed evidence of mechanical stress in the target tissues as stretched collagen was prominent in the tendon, navicular bone and fibrocartilage, and the impar and collateral sesamoidean ligaments and correlated with the sites of tissue damage. The identification of widespread mechanical damage in the soft tissues of the navicular enthesis organ in affected horses confirms its function as a tensegrity structure and emphasizes the relevance of biotensegrity models in understanding the pathogenesis of DJD.Support or Funding InformationLSU SVM Charles V. Cusimano Equine Health Studies ProgramThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Isolated rupture of the vastus lateralis tendon: Case report

We report a patient with a history of bariatric surgery who have an isolated rupture of the unilateral vastus lateralis tendon from the adhesion site on the patella. The diagnosis was missed in this case and was placed with magnetic resonance (MR) investigation of the patient during follow-up. A 40-year-old male patient felt pain in his knee after an awkward movement. Initially, because of his bariatric surgery, he had some other complaints, the diagnosis was missed, and the patient had conservative treatment and physical therapy applied. When complaints did not improve, MR was taken, and the vastus lateralis tendon was identified to have ruptured from the patella in isolation. Treated surgically, the patient had no new rupture on check-up performed 1 year later. The patient is fully healed. After the bariatric surgery, some metabolic changes and weakness at the osteotendinous junction of muscles may occur. Isolated vastus lateralis rupture is rarely observed, and diagnosis may be missed. In these patients, surgical treatment is required and other accompanying pathologies of the knee should also be treated at the same time.

Correlating Increased Mechanical Forces with Tissue Lesions in Equine Navicular Disease

Navicular disease is a common form of chronic lameness in horses that currently can only be managed but not effectively treated. The navicular apparatus is a functional enthesis organ very similar to the human Achilles, and is highly adapted to dissipate forces away from the osteotendinous junction between the deep digital flexor tendon and the distal phalanx. Force analyses using 3D models constructed from CT scans of a horse's forelimb indicate that an exaggerated dorsiflexion of the foot, a posture commonly observed in horses with navicular disease, puts the deep digital flexor tendon under greater tension. With this in mind, tissue lesions in the navicular enthesis organ in horses euthanized for navicular disease were correlated with the force analysis. Areas of tension in the deep flexor tendon and underlying adipose tissue were identified by differential histological staining of stretched versus relaxed collagen using Masson's trichrome and picrosirius red. These areas correlated with tendon lesions documented by MRI and were in line with compressive lesions in the navicular bone. The dorsiflexed position of the foot was also found to increase forces on the impar and suspensory ligaments in which enthesial loss and disruption of collagen fibers and deposits of cartilage and bone was documented. These findings confirm the primary mechanical pathogenesis of navicular disease and indicate that rehabilitative therapy focused on decreasing dorsiflexion of the foot by reducing overloading of the forelimb is likely to be an effective treatment for many cases of navicular disease.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Factors Affecting Early Single Heel Raise after Repair of Achilles Tendon Rupture

Category: Sports Introduction/Purpose: No physical exam or clinical test can clearly predict a final course of acute Achilles tendon rupture after surgical treatment. But, in recent studies, ability to perform single-heel-raise during the early postoperative period was considered as a significant prognostic factor. Therefore, analysis of the relationship between preoperative factors and timing of the single heel raise might help to predict the prognosis and aid to establish an individualized rehabilitation plan. The purpose of this study was to analyze the factors affecting early single heel raise after surgical treatment of acute Achilles tendon rupture. Methods: From January 2012 to August 2015, a retrospective analysis was performed for 68 patients who met the inclusion criteria among 98 cases of surgically treated acute Achilles tendon rupture. Operative technique and rehabilitation protocol were same in all cases. The patients who were able to perform a single heel raise within 3 months postoperatively were classified into the study group and the rest was determined as the control group. During periodic outpatient observation, we evaluated Achilles tendon total rupture score (ATRS), Visual Analog Scale (VAS), and timing capable of a single heel raise. We also preoperatively measured defect size and distance between calcaneal osteotendinous junction and rupture site by ultrasound image in all cases. Results: No difference was found in demographic factors between the study group (23 cases) and the control group (45 cases) who performed a single heel raise later than 3 months postoperatively. There were no significant difference in defect size and distance between calcaneal osteotendinous junction to the rupture site (P=0.38, P=0.63). However, when the rupture site was divided into hyporvascular zone (from calcaneal osteotendinous junction to the rupture site: 4~7 cm) and hypervascular zone, the study group showed a significantly low hyporvascular zone rupture rate. (14/23, 41/45, P=0.003). Also, in the logistic regression analysis that included age, BMI, smoking, hyporvascular zone rupture, defect size, and operation delay, patients with hypervascular region rupture showed odds ratio of 5.3 (P=0.017) in performing a single heel raise within postoperative 3 month. ATRS score at postoperative 3 months and last f/u were significantly higher in the study group. (p&lt;0.01) Conclusion: Achilles tendon rupture at hypovascular zone is a poor prognostic factor for the early single heel raise and might significantly affect the prognosis after acute Achilles tendon rupture operation.

Bilateral Simultaneous Rupture of the Quadriceps Tendons in Healthy Individuals

Quadriceps tendon rupture is an uncommon injury in healthy individuals. This paper presents two case reports of patients of bilateral quadriceps tendon rupture, who were misdiagnosed as muscle weakness of quadriceps with contusion of the knee joint. Subsequent physical examination showed a supra-patellar gap, moderate hemarthrosis of both knees, and failure of active knee extension. MRI showed bilateral rupture of the quadriceps tendons at the osteotendinous junction. Radiographs described the depression in the suprapatellar soft tissue, patella baja and an avulsion bony fragment on the patella. Surgery confirmed the MRI observation, so transosseous suturing and augmentation were undertaken. Both patients returned to a normal life with useful function. Adequate physical examination and correct understanding of both radiograph and MRI were required to prevent misdiagnosis.

Regeneration techniques for bone-to-tendon and muscle-to-tendon interfaces reconstruction.

The complex structure of the bone-tendon and muscle-tendon junctions makes their reproduction for tissue engineering applications very difficult. Relatively few studies have investigated the characteristics of these regions from a tissue engineering view point. PubMed, Thomson Reuters, Scopus and Google Scholar databases were searched using various combinations of the keywords 'Tendon', 'Myotendinous junction', 'Osteotendinous junction', 'Tissue engineering' and 'Scaffold'. The available studies can be divided according to whether the objective is to build an entire composite tissue unit or to assist the recreation of interfaces, such as improving integration of autografts with the surrounding bone or with the muscle. The most used techniques are based on the electrospinning and the self-reorganized constructs process, which were applied to both bone-to-tendon junction (BTJ) and muscle-to-tendon junction (MTJ) regeneration. The use of nanofibers that mimic the hierarchical structure of the extracellular matrix (ECM), eventually functionalized by encapsulation of bioactive components, allowed cell attachment and differentiation. There have been no translational investigations. There is a need to devise suitable techniques that allow suitable tissue engineering of BTJ and MTJ. Appropriately planned studies are needed to translate tissue engineering from a scientific challenge to a clinically applicable technique.

Detrimental Effect of Repeated and Single Subacromial Corticosteroid Injections on the Intact and Injured Rotator Cuff

Background: The effect of corticosteroids on tendons is poorly understood, and current data are insufficient and conflicting. Purpose: To evaluate the effects of corticosteroid injections on intact and injured rotator cuffs (RCs) through biomechanical and radiographic analyses in a rat model. Study Design: Controlled laboratory study. Methods: A total of 70 rats were assigned to 7 groups. Uninjured rats (no tear) received either a single saline injection, a single methylprednisolone acetate (MTA) injection, or triple MTA injections. Injured rats (unilateral supraspinatus injury) received either a single saline injection, triple saline injections, a single MTA injection, or triple MTA injections (injections were subacromial; repeat injections were administered weekly). Rats were sacrificed 1 week after final injection. Shoulders were harvested and grossly inspected, and the supraspinatus tendon was evaluated biomechanically. Bone density at the tendon insertion site on the greater tuberosity was assessed by micro–computed tomography. Results: Intact RCs exposed to triple MTA injections had significantly decreased maximal load and stiffness compared with the control group (14.43 vs 21.25 N and 8.21 vs 16.6 N/mm, respectively; P < .05). Injured RCs exposed to steroid treatment had significantly lower maximal load (single saline: 10.91 N, single steroid: 8.43 N [P < .05]; triple control: 15.77 N, triple steroid: 11.65 N [P < .05]) compared with the control at 3 weeks. Greater tuberosity volume density and connectivity density were significantly lower in undamaged rats after triple MTA injection (P < .05). Conclusion: The study results clearly showed that repeated doses of corticosteroids significantly weaken rat RC and negatively affect bone quality in addition to possibly causing deterioration of the osteotendinous junction. However, data retrieved from animals must be scrupulously analyzed before extrapolation to humans. As such, the potential benefits and harms of subacromial corticosteroid treatment must be considered before administration. Clinical Relevance: The potential benefit and detrimental effects of corticosteroid injection should be thoroughly considered before it is administered subacromially in patients with RC injuries.

Collagen Scaffolds Incorporating Coincident Gradations of Instructive Structural and Biochemical Cues for Osteotendinous Junction Engineering.

A fully 3D biomaterial containing overlapping gradations of structural, compositional, and biomolecular cues as seen in native orthopedic interfaces is described for the first time. A multi-compartment collagen scaffold is created for engineering tendon-bone junctions connected by a continuous interface that can induce spatially specific MSC differentiation down tenogenic and osteogenic lineages without the use of differentiation media.

EFFECTIVENESS OF ULTRASOUND-GUIDED PERCUTANEOUS ELECTROLYSIS INTRATENDON (EPI) IN THE TREATMENT OF INSERTIONAL PATELLAR TENDINOPATHY IN SOCCER PLAYERS

IntroductionPatellar tendinopathy or ‘jumper's knee’ is considered more of a degenerative (tendinosis) than a non-inflammatory process (tendinitis). Recent histopathological studies have shown the absence of inflammatory cells in this type...

Arterial supply of the tendinous rotator cuff insertions: an anatomical study

Confirming the presence of arteries crossing the osteotendinous junctions (OTJs) of the rotator cuff may explain why rates of avascular necrosis (AVN) of the humeral head vary between three- and four-part proximal humeral fractures. It is hypothesized that the humeral head remains better vascularized in three-part fractures because one tuberosity with its inserting rotator cuff tendons is still attached to the articular fragment and supplying it with blood. Eighty rotator cuff tendons from 20 shoulder girdles of cadavers aged 68-94 years were studied. In six shoulder girdles, the anterior circumflex humeral artery and posterior circumflex humeral artery (PCHA) were injected with ink, and the extra- and intraosseous courses of the vasculature were dissected until the OTJs of the rotator cuff. The rotator cuff insertions received an arterial supply across their OTJs in 50% of cases (75% in supraspinatus, 67% in subscapularis, 33% in infraspinatus and 20% in teres minor). Supraspinatus and subscapularis insertions were vascularized by the arcuate artery, while the insertions of infraspinatus and teres minor were supplied by an unnamed terminal branch of the PCHA. This was named 'posterolateral artery'. The presence of arteries crossing the OTJs of the rotator cuff, as well as the differences in the frequency arteries crossed the OTJs of individual rotator cuff tendons, may help explain why there is a lower rate of AVN of the humeral head in thee-part, compared with four-part proximal humeral fractures.