Healthy Tendon Research Articles

Abstract No. 456 - Image-guided percutaneous treatment of aneurysmal bone cyst of the jaw with bone allograft and autologous bone marrow: a case report with five-year follow-up

No. 456 Image-guided percutaneous treatment of aneurysmal bone cyst of the jaw with bone allograft and autologous bone marrow: a case report with five-year follow-up R. Freitas, K. Fonseca, R. Procopio, L. Lehman; Radiology, Universidade de Sao Paulo Medical School, Sao Paulo, Brazil; Oncology pediatrics, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; Interventional Radiology, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; Buco-maxillo Surgery, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil Purpose: A six-year old boy with an aneurysmal bone cyst of the jaw was treated by percutaneous injection of bone allograft particles mixed with autogenous bone marrow under computed tomography (CT) guidance and general anesthesia. Materials and Methods: A six-year old boy presented with a mass at the left angle of mandible, self-limited recurrent oral bleeding, pallor and severe pain partially controlled with opioids. Open surgical biopsy revealed a fibrous bone lesion with giant cells. A thin-walled 7 x 6 x 6 cm diameter (132 cc) expansible bone lesion at the left angle of mandible containing fluid-fluid levels was detected by X-ray plain film, CT scan, ultrasound, and magnetic resonance imaging. A diagnosis of an aneurysmal bone cyst was stated. A minimally invasive percutaneous approach was proposed after multidisciplinary review and an informed consent was obtained. Frozen dried bone allograft particles obtained from tissue bank were crushed, mixed with fresh autogenous bone marrow and injected into the lesion by a percutenous 11-gauge needle under CT and fluoroscopy guidance. No complications were observed. Results: The patient was discharged from the hospital the next day without symptoms. After two weeks he returned at consultation without bleeding or pain complaints. Normal serum hemoglobin was observed three months later. CT scans performed during five years of follow up showed progressive healing, ossification of the left branch of the jaw, tumor shrinking and remodeling. No pain or bleeding was reported since the percutaneous treatment. Conclusion: This case report shows excellent healing of a locally aggressive aneurysmal bone cyst after image-guided percutaneous injection of autogenous bone marrow mixed with elements of allograft bone matrix. Five years of follow-up showed excellent functional and cosmetic results. Further research is required to clarify the exact mechanisms of this potential treatment. Educational Exhibit Abstract No. 457 Ultrasound guided percutaneous tenotomy/ fasciotomy: indications, technique, and initial experience A.S. Johar, M.C. Switzer, A. Braun; Radiology, Maricopa Medical Center, Phoenix, AZ Learning Objectives: The objective of this poster is to 1) Discuss the pathophysiology of tendinosis and the common clinical presentations. 2) Review the US findings of chronic tendinopathy. 3) Describe the percutaneous tenotomy technique and its advantages over traditional tendinopathy treatments. 4) Outline our initial experience with outpatient ultrasound tenotomy. Background: Tendinopathy is a common and underdiagnosed pathology which often impairs daily and recreational activities. Given its debilitating nature, a range of treatment options exist, many of which are conservative and few of which provide durable complete symptom relief. Ultrasound guided percutaneous tenotomy is a relatively new and promising technique with the ability to remove pain causing diseased tendon tissue without damaging the adjacent healthy tendon tissue. This technique is gaining traction due to its minimally invasive nature, quick recovery time, low cost, low morbidity and durable positive outcomes. Clinical Findings/Procedure Details: We will demonstrate the findings of tendinopathy by presenting supporting US images from multiple cases. We will detail the percutaneous ultrasonic tendon cutting and debriding technique while describing pertinent pearls and pitfalls. Finally, we will discuss the outcomes from our cases. Conclusion and/or Teaching Points: After reviewing the poster, viewers will be familiar with the pathology, presentation and imaging findings of chronic tendinopathy. Viewers should appreciate US guided percutaneous tenotomy as a minimally invasive, fast and effective treatment option for tendinopathy pain. Educational Exhibit Abstract No. 458 Lymphangiography: not gone, not forgotten E. Lindgren, J. Friese, C.E. Bender; Radiology, Mayo Clinic, Rochester, MN JVIR ’ Posters and Exhibits S199

Study of Bone Marrow Mesenchymal and Tendon-Derived Stem Cells Transplantation on the Regenerating Effect of Achilles Tendon Ruptures in Rats.

Comparative therapeutic significance of tendon-derived stem cells (TDSCs) and bone marrow mesenchymal stem cells (BMSCs) transplantation to treat ruptured Achilles tendon was studied. Three groups of SD rats comprising 24 rats each, designated as TDSCs and BMSCs, and nontreated were studied for regenerative effects through morpho-histological evaluations and ultimate failure load. For possible mechanism in tendon repair/regeneration through TDSCs and BMSCs, we measured Collagen-I (Col-I), Col-III gene expression level by RT-PCR, and Tenascin-C expression via immunofluorescent assay. TDSCs showed higher agility in tendon healing with better appearance density and well-organized longitudinal fibrous structure, though BMSCs also showed positive effects. Initially the ultimate failure load was considerably higher in TDSCs than other two study groups during the weeks 1 and 2, but at week 4 it attained an average or healthy tendon strength of 30.2 N. Similar higher tendency in Col-I/III gene expression level during weeks 1, 2, and 4 was observed in TDSCs treated group with an upregulation of 1.5-fold and 1.1-fold than the other two study groups. Immunofluorescent assay revealed higher expression of Tenascin-C in TDSCs at week 1, while both TDSCs and BMSCs treated groups showed detectable CM-Dil-labelled cells at week 4. Compared with BMSCs, TDSCs showed higher regenerative potential while treating ruptured Achilles tendons in rats.

Tendon et tendinopathie

The tendon, connective fibrous tissue, mechanically responsible for the transmission of strength of muscles to bones, is a dynamic entity which, according to the constraints, restructures permanently and, thanks to various metabolic and mechanical changes. This review describes the histology, vascularization and innervation of the healthy tendon. In addition, the biomechanics and tendinous physiological responses, as well as the pathophysiology of tendinopathy are exposed.

Stereological Quantification of Immune-Competent Cells in Baseline Biopsy Specimens From Achilles Tendons

Background: Limited data exist on the presence and function of immune-competent cells in chronic tendinopathic tendons and their potential role in inflammation and tissue healing as well as in predicting long-term outcome. Purpose: To quantify subtypes of immune-competent cells in biopsy specimens from nonruptured chronic tendinopathic Achilles tendons and healthy control tendons. In addition, to examine whether findings in baseline cell biopsy specimens can predict the long-term presence of Achilles tendon symptoms. Study Design: Cross-sectional and case-control study; Level of evidence, 3. Methods: Fifty patients with nonruptured chronic Achilles tendinopathy and 15 healthy participants were included. At time of inclusion, an ultrasound examination was performed immediately before an ultrasound-guided Achilles tendon biopsy specimen was obtained. Tissue samples were evaluated immunohistochemically by quantifying the presence of macrophages (CD68-PGM1+, CD68-KP1+), hemosiderophages (Perls blue), T lymphocytes (CD2+, CD3+, CD4+, CD7+, CD8+), B lymphocytes (CD20+), natural killer cells (CD56+), mast cells (NaSDCl+), Schwann cells (S100+), and endothelial cells (CD34+) using a stereological technique. A follow-up examination was conducted more than 4 years (range, 4-9 years) after the biopsy procedure to evaluate the long-term presence of Achilles tendon symptoms. Results: Macrophages, T lymphocytes, mast cells, and natural killer cells were observed in the majority (range, 52%-96%) of biopsy specimens from nonruptured chronic tendinopathic Achilles tendons. CD68-KP1+ macrophages (0.29% vs 0; P = .005) and CD34+ endothelial cells (3% vs 0.97%; P = .04) were significantly more numerous in tendinopathic tendons compared with healthy tendons. The presence of iron+ hemosiderophages was more frequently observed in biopsy specimens obtained from the group who was asymptomatic at follow-up compared with the symptomatic group (42% vs 5%; P = .02). Conclusion: This study provides evidence for the presence of immune-competent cells in the majority of biopsy specimens from nonruptured chronic tendinopathic Achilles tendons. Macrophages and endothelial cells were significantly more numerous in tendinopathic tendons than in healthy tendons. The presence of iron+ hemosiderophages in baseline biopsy specimens was associated with a good prognosis. Clinical Relevance: New insight into the role of immune-competent cells in chronic Achilles tendinopathy.

Experimentelle Sehnenregeneration von Rotatorenmanschettendefekten mit autologen Tenozyten und einem biodegradablen Kollagen-Scaffold im Schafmodell

BackgroundTendon engineering still represents a main problem in rotator cuff repair. For this purpose colonization of a scaffold with cultivated cells potentially leads to an improvement. Hypothesis of this study was that autologous tenocytes seeded on biodegradable collagen-based scaffolds have the potential to improve tendon healing in a massive rotator cuff lesions in a sheep model. Materials and MethodsA defect with a size of 3.5×1.5cm in the tendon-bone junction of infraspinatus tendon of 24 sheep (3 groups with each 8 animals) was created. Group I served as defect group. Animals in group II received the implantation of a biodegradable collagen-based scaffold. In group III a collagen-based scaffold seeded with autologous tenocytes was implanted. 12 weeks postoperatively the regenerated tendons were examined with biomechanical testing. ResultsIn biomechanical testing, healthy control tendons showed an average tensile strength of 2995N. The mean tensile strength for groups I-III was 2004N, 2088N and 2516N. Data for group III did not differ significantly (p=0.0938) from native controls in ultimate tensile regarding strength (N) and breaking stress (N/mm2). ConclusionsUse of autologous tenocytes seeded on biodegradable collagen-based scaffold in large animal model results in superior biomechanical outcome compared to unsupplied defect and defect coverage with non-colonized scaffold. Level of evidenceLevel IV.

In vitro functional response of human tendon cells to different dosages of low-frequency pulsed electromagnetic field.

Chronic tendinopathy is a degenerative process causing pain and disability. Current treatments include biophysical therapies, such as pulsed electromagnetic fields (PEMF). The aim of this study was to compare, for the first time, the functional in vitro response of human tendon cells to different dosages of PEMF, varying in field intensity and duration and number of exposures. Tendon cells, isolated from human semitendinosus and gracilis tendons (hTCs; n = 6), were exposed to different PEMF treatments (1.5 or 3 mT for 8 or 12 h, single or repeated treatments). Scleraxis (SCX), COL1A1, COL3A1 and vascular endothelial growth factor-A (VEGF-A) expression and cytokine production were assessed. None of the different dosages provoked apoptotic events. Proliferation of hTCs was enhanced by all treatments, whereas only 3 mT-PEMF treatment increased cell viability. However, the single 1.5 mT-PEMF treatment elicited the highest up-regulation of SCX, VEGF-A and COL1A1 expression, and it significantly reduced COL3A1 expression with respect to untreated cells. The treated hTCs showed a significantly higher release of IL-1β, IL-6, IL-10 and TGF-β. Interestingly, the repeated 1.5 mT-PEMF significantly further increased IL-10 production. 1.5 mT-PEMF treatment was able to give the best results in in vitro healthy human tendon cell culture. Although the clinical relevance is not direct, this investigation should be considered an attempt to clarify the effect of different PEMF protocols on tendon cells, in particular focusing on the potential applicability of this cell source for regenerative medicine purpose, both in surgical and in conservative treatment for tendon disorders.

Reversal of Peroneal Tenodesis With Allograft Reconstruction of the Peroneus Brevis and Longus: Case Report and Surgical Technique.

Chronic peroneal tendinopathy and tears represent a challenging clinical situation. Traditionally, tenodesis of the torn tendon to the remaining healthy tendon has been advocated if more than half of the tendon is compromised. Allograft reconstructions have been reserved for patients with functional muscles and both peroneal tendons extensively compromised. We report a unique case of a peroneal tenodesis takedown and reconstruction of both peroneal tendons using semitendinosus allograft. A description of the surgical technique and tips are provided. Peroneal tendon function is crucial to maintain a balanced hindfoot. To the best of our knowledge, reconstruction of both peroneal tendons after a tenodesis has not been previously reported. Allograft reconstruction of the peroneal tendons arises as a feasible alternative in patients with residual pain and weakness after a failed tenodesis surgery LEVELS OF EVIDENCE: Therapeutic Level IV, case study.

AB0981 Tendon Involvement in Patients with Gout. an Ultrasound (US) Prevalence Study

BackgroundChronic gout is characterized by urate monosodium crystals (MSU) deposition in different tissues, mostly in soft tissues and the joints of lower extremities. The prevalence of tendon involvement by gout...

Achilles tendinopathy recovery after a single autologous PRP injection monitored by ultrasound

BackgroundAchilles tendinopathy remains often chronic and rebel to a thorough conservative treatments. In this context, autologous platelet-rich plasma (PRP) could represent an interesting alternative. MethodsThis prospective, monocentric, descriptive study, conducted from January 2011 to May 2011, included 32 patients practicing sports at the competitive or amateur level and suffering from chronic Achilles tendinopathy diagnosed by ultrasound (US). The treatment consisted on a single injection of PRP directly into the Achilles tendon under US guidance. Hence, the cracks were gently filled without damaging the surrounding healthy tendon. PRP was systematically characterized before its administration. Tendon regeneration was followed using algofunctionnal testing and US examination at 1, 2, and 3months post-injection. A satisfaction score was proposed at 6 and 12months by phone call. ResultsTwenty-two patients (69%) at 1month and 18 patients (88%) at 2months were completely healed, associated with a widespread improvement of fibrillar echo-structure of the tendon and improvement reduction of the hypervascularity during power Doppler examination at 3months. Of the 22 responses collected to the end of the protocol, 14 patients declared a complete improvement in term of satisfaction with a significant reduction of pain (P<0.05), 4 patients reported a significant reduction of pain more than 50% (P<0.05). Only 4 patients did not respond to the treatment and were secondary operated. ConclusionsA single autologous PRP injection was effective in the treatment of rebel Achilles tendinopathy. US guidance allows PRP injection directly into the degenerated part of the tendon with great accuracy.

Plantarflexor muscle function in healthy and chronic Achilles tendon pain subjects evaluated by the use of EMG and PET imaging

BackgroundAchilles tendon pathologies may alter the coordinative strategies of synergistic calf muscles. We hypothesized that both surface electromyography and positron emission tomography would reveal differences between symptomatic and asymptomatic legs in Achilles tendinopathy patients and between healthy controls. MethodsEleven subjects with unilateral chronic Achilles tendon pain (28years) and eleven matched controls (28years) were studied for triceps surae and flexor hallucis longus muscle activity in response to repetitive isometric plantarflexion tasks performed at 30% of maximal voluntary contraction using surface electromyography and glucose uptake using positron emission tomography. Additionally, Achilles tendon glucose uptake was quantified. FindingsNormalized myoelectric activity of soleus was higher (P<0.05) in the symptomatic leg versus the contralateral and control legs despite lower absolute force level maintained (P<0.005). Electromyography amplitude of flexor hallucis longus was also greater on the symptomatic side compared to the healthy leg (P<0.05). Both the symptomatic and asymptomatic legs tended to have higher glucose uptake compared to the control legs (overall effect size: 0.9 and 1.3, respectively). Achilles tendon glucose uptake was greater in both legs of the patient group (P<0.05) compared to controls. Maximal plantarflexion force was ~14% greater in the healthier leg compared to the injured leg in the patient group. InterpretationsWhile the electromyography showed greater relative amplitude in the symptomatic leg, the results based on muscle glucose uptake suggested relatively similar behavior of both legs in the patient group. Higher glucose uptake in the symptomatic Achilles tendon suggests a higher metabolic demand.

ECCENTRIC TRAINING IMPROVES TENDON BIOMECHANICAL PROPERTIES: A RAT MODEL

BackgroundEven if eccentric exercises appear favourable in primary prevention of tendons lesions and, especially, in secondary prevention after tendinopathy, the biomechanical changes to the tissue are not yet clear.ObjectiveWe aimed...

Eccentric exercise: acute and chronic effects on healthy and diseased tendons

Eccentric exercise can influence tendon mechanical properties and matrix protein synthesis. mRNA for collagen and regulatory factors thereof are upregulated in animal tendons, independent of muscular contraction type, supporting the view that tendon, compared with skeletal muscle, is less sensitive to differences in type and/or amount of mechanical stimulus with regard to expression of collagen, regulatory factors for collagen, and cross-link regulators. In overused (tendinopathic) human tendon, eccentric exercise training has a beneficial effect, but the mechanism by which this is elicited is unknown, and slow concentric loading appears to have similar beneficial effects. It may be that tendinopathic regions, as long as they are subjected to a certain magnitude of load at a slow speed, independent of whether this is eccentric or concentric in nature, can reestablish their normal tendon fibril alignment and cell morphology.

Real time evaluation of monolateral clubfoot with sonoelastography

This study was undertaken to assess the feasibility of real-time elastosonography (RTE) of Achilles tendon in the clinical evaluation of a cohort of children affected by unilateral clubfoot, not surgically treated. Twenty patients affected by unilateral clubfoot were evaluated. The study group consisted of 8 males and 12 females (mean age, 16 ± 7.3 months), all treated with the Ponseti method. Children were divided into two groups according to age: group 1 aged 0-18 months, and group 2 aged 18-60 months. Any further systemic pathological conditions were considered exclusion criteria. For each subject, RTE examination of the Achilles tendons was performed bilaterally, and then regions of interest (ROIs) were positioned. In children aged 0-18 months, the mean value ROI 1/mean value ROI 2 ratio was 2.0 ± 0.18 and it showed a statistically significant difference if compared to the same ratio from healthy tendons, 2.5 ± 0.17 (p < 0.05). In group 2 (children aged 18-60 months) the mean ROI 1/mean value ROI 2 ratio value was 1.8 ± 0.27, compared to a 2.04 ± 0.21 (p < 0.05) ratio in healthy tendons. RTE is a feasible, reliable and easily performed technique that allows an accurate study of the mechanical properties of Achilles tendon in children with clubfoot.

Stem Cell-Bearing Suture Improves Achilles Tendon Healing in a Rat Model

Tendon healing is a slow and complicated process that results in inferior structural and functional properties when compared to healthy tendon tissue. It may be possible to improve outcomes of tendon healing with enhancement of biological aspects of the repair including tissue structure, organization, and composition. The purpose of this study was to determine whether use of a stem cell-bearing suture improves Achilles tendon healing in a rat model. The Achilles tendon was transected in 108 bilateral hind limbs from 54 rats. Each limb was randomized to repair with suture only (SO), suture plus injection (SI) of mesenchymal stem cells (MSCs) at the repair site, or suture loaded with MSCs (suture with stem cells, SCS). One half of the animals were randomly sacrificed at 14 and 28 days after surgery and the Achilles tendon was harvested. From each repair group at each time point, 12 limbs were randomized to biomechanical testing and 6 to histologic analysis. Tendons were loaded using a 223-N load cell at 0.17 mm/s. A blinded pathologist scored the histology sections. Ultimate failure strength (N/mm(2)) was significantly higher in the SI and SCS groups versus the SO group. In the SI group, ultimate failure strength decreased significantly at 28 days versus 14 days. Histology score in the SCS group was significantly lower (better) than in both other groups (P ≤ .001). Histology findings at day 28 were significantly higher versus day 14 for all groups (P = .01). Both the SI and the SCS groups had significantly higher ultimate failure strength versus the SO group, and strength was maintained at 28 days in the SCS group but not in the SI group. Histology in the SCS group was significantly better than in both other groups. These findings in a rat model suggest that the use of stem cells enhances healing after Achilles repair and that embedding of stem cells directly into suture offers sustained early benefit to tendon healing.

Neuronal pathways in tendon healing and tendinopathy--update.

The regulatory mechanisms involved in tendon homeostasis and repair are not fully understood. Accumulating data, however, demonstrate that the nervous system, in addition to afferent (sensory) functions, through efferent pathways plays an active role in regulating pain, inflammation, and tissue repair. In normal-, healing- and tendinopathic tendons three neurosignalling pathways consisting of autonomic, sensory and glutamatergic neuromediators have been established. In healthy tendons, neuromediators are found in the paratenon, whereas the proper tendon is practically devoid of nerves, reflecting that normal tendon homeostasis is regulated by pro- and anti-inflammatory mediators from the tendon surroundings. During tendon repair, however, there is extensive nerve ingrowth into the tendon proper and subsequent time-dependent appearance of sensory, autonomic and glutamatergic mediators, which amplify and fine-tune inflammation and tendon regeneration. In tendinopathy, excessive and protracted sensory and glutamatergic signalling may be involved in inflammatory, painful and hypertrophic tissue reactions. As our understanding of these processes improves, neuronal mediators may prove to be useful in the development of targeted pharmacotherapy and tissue engineering approaches to painful, degenerative and traumatic tendon disorders.

Thyroid hormones increase collagen I and cartilage oligomeric matrix protein (COMP) expression in vitrohuman tenocytes

we previously demonstrated the presence of high levels of thyroid hormones (THs) receptors isoforms in healthy tendons, their protective action during tenocyte apoptosis, and the capability to enhance tenocyte proliferation in vitro. In the present study we tested the ability of THs to influence ECM protein tenocyte secretion in an in vitro system. primary tenocyte-like cells were cultivated for 1, 7 and 14 days in the presence of T3 or T4 individually or in combination with ascorbic acid (AA). THs (T3 or T4) in synergism with AA increase significantly the total collagen production after 14 days. THs in synergism with AA increase significantly the expression of collagen I,biglycan and COMP, after some days. THs play a role on the extra cellular matrix of tendons, enhancing in vitro the production of several proteins such as collagen I, biglycan and COMP. THs receptors are active on human tenocytes, and can play a role in tendon ailments.

Exploring the role of hypercholesterolemia in tendon health and repair

High cholesterol remains a significant healthcare problem, as more than 13% of adults in the U.S. are affected by hypercholesterolemia. The detrimental effects the disease has on cardiovascular health are well-documented, but the effects on the musculoskeletal system, and more specifically on tendons, have not been thoroughly examined. This paper provides an overview of work performed in our lab with various animal models to elucidate the relationship between high cholesterol and tendon biomechanical integrity and ability to heal. These studies highlight the complexity of relationships between multiple factors that influence tendon biomechanics, and it has offered a better understanding of the implications of high cholesterol on healthy and healing tendons.

Minimally Invasive Repair of the Tibialis Anterior Tendon Using a Semitendinosus Autograft

Ruptures of the tibialis anterior tendon are rare but can cause substantial functional deficiencies. The literature regarding the treatment of such injuries is very limited. Atraumatic ruptures often occur in the presence of an abnormal tendon structure, and retraction often makes end-to-end repair impossible. With traumatic lesions, the risk of developing both adhesions and scar tissue is high. This study assesses the results of a surgical reconstruction using the interposition of a semitendinosus tendon autograft in 12 patients. Three patients had a traumatic rupture, and 9 patients had an atraumatic rupture. In 8 patients, the procedure was carried out using a minimally invasive technique. The average postoperative American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot score was 95.7 in the atraumatic group and 94.7 in the traumatic group. Active dorsiflexion was possible after 2 to 3 weeks. We believe that the interposition of a strong, healthy tendon facilitated healing and allowed early weight bearing. All patients had good recovery of dorsiflexion and gait. Repairing a ruptured tibialis anterior tendon using a semitendinosus autograft was a reliable technique and offered a good result. With the minimally invasive approach, there was no need to divide the extensor retinaculum, which we believe allowed faster recovery and reduced the risk of adhesions and wound healing problems. Level IV, retrospective case series.

Influence of physical activity on T1 and T2* relaxation times of healthy achilles tendons at 3T

To evaluate longitudinal (T1) and transverse (T2*) relaxation times at different Achilles tendon locations (insertion, mid-portion, and musculotendinous area) in a cohort of subjects with variable tendon straining activity, but without any signs of tendinopathy. T1 and T2* relaxation times of the Achilles tendon were measured using an ultrashort echo time (UTE) imaging sequence with flip angle and echo time variation on a 3T whole-body clinical magnetic resonance (MR) scanner. Twenty-four tendons of 12 healthy volunteers and 18 tendons of nine healthy recreational long-distance runners (average weekly running distance of 47.4 ± 5.3 km) were enrolled. Mean T1 values of the whole tendon showed no marked group differences, whereas T2* relaxation times of runners were significantly longer (mean percentage increase 15.7 ± 4.9%; P = 0.0181) compared to controls. Regarding group differences for the investigated insertional, mid-portion, and musculotendinous area of the Achilles tendon, only the mid-portion of the Achilles tendon in the running group presented significantly longer T2* values (mean percentage increase 29.1 ± 23.0%; P = 0.0420) in comparison to the control group. Prolonged T2* values especially in the mid-portion of the Achilles tendon of runners are likely to reflect an adaptation of the tendon microstructure to repetitive tendon straining activity.

Ultrasound elastography is a reproducible and feasible tool for the evaluation of the patellar tendon in healthy subjects

To evaluate the feasibility and reproducibility of ultrasound elastography (UE) in the assessment of healthy patellar tendon and to describe its UE pattern. Twenty-two patellar tendons of 11 out of 16 healthy subjects who met the inclusion criteria were evaluated three times by ultrasound (US) and UE at their proximal, middle and distal portions, by two separate sonographers with different experiences in UE. In all tendon portions the color map analysis showed a predominance of green (highly elastic), with good values of intra-observer (Operator 1: P-values = 0.790, 0.864, 0.865; Operator 2: P = 0.642, 0.882, 0.613 for proximal, middle and distal portions, respectively) and inter-observer (P = 0.657) agreement. For both operators the intra-observer analysis of the elasticity ratio (ER) between the tendon and the subcutis showed high agreement values (P < 0.001 for both operators). The inter-observer analysis showed also high agreement values (P < 0.001 at proximal, P = 0.001 at middle, P = 0.005 at distal portions). The overall analysis of the ER of the tendon portions showed values of (mean ± SD): 1.47 ± 0.64, 4.38 ± 1.36, 3.32 ± 1.20 for proximal, middle and distal portions, respectively. The mean time to perform the UE evaluation for the inexperienced operator was 5 min at the beginning of the study but decreased to 2 min after a few examinations were done. The mean time for the expert was 2 min for the entire study. UE is a feasible and reproducible tool for the evaluation of the healthy patellar tendon and further data are needed to define its role in the assessment of tendon pathology.