Prevalence Of Bone Marrow Edema Research Articles

Association of anatomical variants of the sacroiliac joint with bone marrow edema in patients with axial spondyloarthritis.

To determine the prevalence of sacroiliac joint variants in patients with axial spondyloarthritis (axSpA) using MRI-based synthetic CT images and to evaluate their relationships with the presence of bone marrow edema, as this may potentially complicate diagnosing active sacroiliitis on MRI in patients with suspected axSpA. 172 patients were retrospectively included. All patients underwent MRI because of clinical suspicion of sacroiliitis. The diagnosis of axSpA was made by a tertiary hospital rheumatologist. Two readers independently determined the presence of bone marrow edema and the presence of one or more of the nine known sacroiliac joint (SIJ) variants. SIJ variants were common in axSpA patients (82.9%) and the non-SpA group (85.4%); there were no significant differences in prevalence. Bone marrow edema was frequently found in axSpA (86.8%) and non-SpA patients (34%). AxSpA patients with SIJ variants (except for accessory joint) demonstrated 4 to 10 times higher odds for bone marrow edema, however not statistically significant. The more variants were present in this group, the higher the chance of bone marrow edema. However, some multicollinearity cannot be excluded, since bone marrow edema is very frequent in the axSpA group by definition. SIJ variants are common in axSpA and non-SpA patients. SIJ variants were associated with higher prevalence of bone marrow edema in axSpA patients, potentially due to altered biomechanics, except for accessory joint which may act as a stabilizer.

Sacroiliac joint MRI for diagnosis of ax-SpA: algorithm to improve the specificity of the current ASAS MRI criteria.

To compare sacroiliac joint (SIJ) lesions on MRI in women with versus without axial spondyloarthritis (ax-SpA) and establish an algorithm to determine whether such lesions are due to ax-SpA. This retrospective comparative study assessed bone marrow edema (BME), sclerosis, erosions, osteophytes, and ankylosis at the SIJ in two groups of women, one with and another without ax-SpA. Sensitivity and specificity were calculated for combinations/characteristics of lesions, using rheumatologists' assessment with assessment of spondyloarthritis international society (ASAS) criteria as the gold standard for diagnosis of ax-SpA. Compared to women without ax-SpA, women with ax-SpA had more BME (61% vs 17%, p < 0.001), sclerosis (40% vs 22%, p < 0.001), erosions (35% vs 5%, p < 0.001), and ankylosis (2% vs 0%, p = 0.007), but less osteophytes (5% vs 33%, p < 0.001). The ASAS MRI criteria yielded 59% sensitivity and 88% specificity, while a new algorithm achieved 56% sensitivity and 95% specificity using the following criteria: no osteophytes at the SIJ and either (i) BME at the SIJ with at least one dimension ≥ 8mm or (ii) at least one erosion at the SIJ. We recommend the following pragmatic algorithm for MRI diagnosis of ax-SpA in women: no osteophytes at the SIJ and either (i) BME at the SIJ with at least one dimension ≥ 8mm or (ii) at least one erosion at the SIJ. The false positive rate when using the new algorithm (3.3%) is less than half than when using the ASAS MRI criteria (7.7%); thus, its application in clinical practice could reduce overdiagnosis and prevent overtreatment of ax-SpA. The developed algorithm has a false-positive rate that is less than half than when using the ASAS MRI criteria (3.3% vs 7.7%), thus its application in clinical practice could reduce overdiagnosis and prevent overtreatment of axial spondyloarthritis. • Compared to women without axial spondyloarthritis (ax-SpA), women with ax-SpA had a significantly higher prevalence of bone marrow edema (BME), sclerosis, erosions, and ankylosis, but a significantly lower prevalence of osteophytes. • A new algorithm for positive ax-SpA based on sacroiliac joint MRI was developed: no osteophytes at the sacroiliac joint (SIJ) and either (i) BME at the SIJ with at least one dimension ≥ 8mm or (ii) at least one erosion at the SIJ. • We recommend this new algorithm for diagnosis of ax-SpA in women, as it has a significantly better specificity than the assessment of spondyloarthritis international society (ASAS) MRI criteria and less than half the false positive rate; thus, its application in clinical practice could reduce overdiagnosis and prevent overtreatment of ax-SpA.

Study on the relationship between severe knee osteoarthritis and bone marrow edema

To investigate the relationship between bone marrow edema and pathological changes, symptoms and signs of severe knee osteoarthritis. From January 2020 to March 2021, 160 patients with severe knee osteoarthritis who underwrent MRI of the knee at the Department of Bone and Joint, Wangjing Hospital, China Academy of Chinese Medical Sciences were included. Eighty patients with bone marrow edema were selected as the case group, including 12 males and 68 females, aged from 51 to 80 years old with an average of (66.58±8.10) years old, the duration of disease 5 to 40 months with an average of (15.61±9.25) months. Eighty patients without bone marrow edema were selected as the control group, including 15 males and 65 females, aged from 50 to 80 years old with an average of (67.82±8.05) years old, the duration of disease 6 to 37 months with an average of (15.75±8.18) months, BMI was (28.26±3.13) kg·m-2 ranged from 21.39 to 34.46 kg·m-2. The degree of bone marrow edema was evaluated by knee whole oragan magnetic resonance imaging score (WORMS). The degree of knee osteoarthritis was evaluated by Kellgren- Lawrence(K-L) grade and Western Ontario and McMaster University Osteoarthritis Index (WOMAC). The degree of joint pain was evaluated by visual analogue scale(VAS) and WOMAC pain score, the joint signs were evaluated by tenderness, percussion pain, joint swelling and joint range of motion. To explore the relationship between bone marrow edema and knee osteoarthritis, the prevalence of bone marrow edema and K-L grade were compared between the two groups. Furthermore the WORMS score and WOMAC index, pain-related score, and sign-related score correlation coefficient were analyzed to further explore the relationship between bone marrow edema and knee osteoarthritis index, joint pain symptoms and signs. There was 68.75% (55/80) of the patients in the case group were in K-L grade Ⅳ, and 52.5% (42/80) in the control group, indicating a higher proportion of patients with grade Ⅳ in the case group than the control group (χ2=4.425, P<0.05). In the case group, there was a strong correlation between bone marrow edema WORMS score and knee osteoarthritis WOMAC index. (r=0.873>0.8, P<0.001), a moderate correlation between WORMS score and VAS score and WOMAC pain score(r=0.752, 0.650>0.5, P<0.001), a moderate correlation between WORMS score and percussion pain score (r=0.784>0.5, P<0.001), and a weak correlation between WORMS score and VAS and tenderness score, joint swelling score and joint range of motion score (r=0.194, 0.259, 0.296<0.3, P<0.001). Our study suggests that severe knee osteoarthritis is associated with an increased risk of bone marrow edema. Bone marrow edema can also lead to knee osteoarthritis joint pain, with percussion pain being a positive sign, but tenderness, joint swelling and limitation of activity are not significantly related to bone marrow edema.

Parallel Line Sign-A New MRI Sign Associated With Chronic Sacroiliitis: Prevalence, Characteristics, and Associations.

Purpose: The purpose is to demonstrate the existence of the parallel line sign (PLS), a dark line parallel to the sacroiliac joint (SIJ), and determine its prevalence, characteristics, and associations. Methods: 200 consecutive SIJ MRIs referred by rheumatologists were retrospectively reviewed for the presence of the PLS. Presence and extent of imaging features of sacroiliitis (bone marrow edema, fatty infiltration, erosions, sclerosis, and ankylosis) were evaluated. Results: Prevalence of PLS was 11.5% (23/200), with 9 subjects having bilateral PLS, resulting in 32 SIJs showing a PLS. Every PLS involved the synovial portion of the SIJ, and almost all (31/32, 96.9%) involved the iliac (rather than sacral) side of the SIJ. Every PLS occurred with at least one established imaging feature of sacroiliitis. Presence of a PLS was associated with higher prevalence of erosions (78.3% vs 36.7% in those without PLS, P < .001), greater extent of SIJ involvement by erosions (3.6 ± 1.3 vs 2.3 ± 1.1 quadrants of the SIJ involved, P < .001), and higher density of erosions per centimeter (88.9% vs 46.2% with >2 erosions/cm, P = .001). There was higher prevalence of bone marrow edema, fatty infiltration, and sclerosis in those with PLS compared to those without PLS (P = .001, P < .001, and P = .006, respectively). Extent of involvement by any of these features was not significantly different between the two groups (P = .22, P = .16, and P = .46, respectively). Conclusions: The PLS is associated with imaging features of chronic sacroiliitis, especially erosions. Knowledge of the existence of the PLS may help avoid misdiagnosis of an insufficiency fracture and increase confidence in the diagnosis of sacroiliitis.

MRI of sacroiliac joints for the diagnosis of axial SpA: prevalence of inflammatory and structural lesions in nulliparous, early postpartum and late postpartum women

ObjectivesTo determine the prevalence of bone marrow oedema (BME) at the sacroiliac joint (SIJ) in early postpartum (EPP), nulliparous (NP) and late postpartum (LPP) women, and to identify factors associated...

The dynamics of morphological changes by MRI at orthovoltage x-ray therapy in patients with gonarthritis stage 0-2: long-term results of a randomized trial

The aim of the study was the comparative analysis of morphological changes dynamics for gonarthritis 0-2 stages by symptomatic therapy (Symptomatic slow acting drugs for osteoarthritis — SYSADOA) in combination with orthovoltage x-ray therapy (OVRT) using magnetic resonance imaging (MRI) on WORMS criteria. Material and methods . The study included the patients with clinically confirmed gonarthritis. All the patients were randomly divided into 2 groups, each received a combined SYSADOA glucosamine (500 mg) and chondroitin (400 mg) sulfate, OVRT was performed for patients of the group 2 performed on Xstrahl-200 equipment, a single dose of 0,45 Gy, in 10 sessions to a total dose of 4,5 Gy. Evaluation of morphological MR-changes was carried out by WORMS in 15 conditional areas calculating of the average value for each anatomical zone before, after 12 and 36 months. Results. There were selected 300 patients, 150 in each group, eight people were lost. The difference in meniscus status was statistically significant before treatment. After 12-36 months a statistically significant advantage of OVRT in cartilage thickness (8,6 vs 1,9; p=0,009), the degree of prevalence of bone marrow edema (5,7 vs 0,6; p=0,024), thinning of articular surfaces (1,6 vs 0,3; p=0,042; t=2,11, df=34), the presence of marginal osteophytes (4,4 vs 1,8; p=0,042) and synovitis (1,1 vs 0,5; p=0,022). Conclusion. Complex MR-evaluation of the results of treatment of gonarthritis according to the WORMS criteria showed a significantly lower rate of progression of pathological changes in patients who received SYSADOA in combination with OVRT compared with patients who were prescribed monotherapy with SYSADOA, the effect remains for at least three years.

Do Patients With Skin Psoriasis Show Subclinical Axial Inflammation on Magnetic Resonance Imaging of the Sacroiliac Joints and Entire Spine?

To explore potential subclinical involvement of the axial skeleton by magnetic resonance imaging (MRI) of the sacroiliac (SI) joints and the entire spine in patients with skin psoriasis without clinical evidence of peripheral or axial inflammation. Twenty patients with skin psoriasis but no clinical evidence of peripheral or axial inflammation and 22 healthy controls underwent standardized dermatologic and rheumatologic clinical examination and unenhanced 1.5T MRI of the SI joint and the entire spine. Two blinded readers globally assessed the presence or absence of SI joint inflammation simultaneously on T1-weighted and short tau inversion recovery MRI sequences with a confidence estimate. Bone marrow edema, fat metaplasia, erosion, and ankylosis of the SI joint, and vertebral corner inflammatory lesions and fat lesions were recorded using standardized modules. The prevalence of each lesion type was calculated in both groups, averaged across 2 readers. The number of subjects with lesions in the SI joint and spine (≥1, 2, 3, 4, or 5 lesions) as concordantly assessed by both readers was recorded. The median duration of skin psoriasis was 23.0 years, the median age of patients was 48.5 years, and 25.0% of patients and 9.1% of healthy controls were concordantly classified by both readers as having SI joint inflammation (P = 0.23). The prevalence of bone marrow edema and structural lesions was comparable across patients and controls, both on SI joint and spine MRI. In this controlled study, patients with skin psoriasis but no clinical arthritis or spondylitis showed limited evidence of concomitant subclinical axial involvement by SI joint and spine MRI. These findings do not support routine screening for subclinical axial inflammation in patients with longstanding skin psoriasis.

Mimics of axial spondyloarthritis.

Axial spondyloarthritis (AxSpA) is a distinct clinical entity with characteristic clinical and radiographic features; however, a multitude of other metabolic, infectious and inflammatory disorders mimic it both clinically and radiographically. We present in this review article recent updates about the various disease entities and conditions that may mimic AxSpA and how to differentiate among them. The sensitivity and specificity of MRI in diagnosing AxSpA has limitations and needs to be interpreted in the context of the clinical picture. Interestingly, some recent studies have highlighted that a relatively high prevalence of bone marrow edema on pelvic MRIs in healthy volunteers which could even be categorized as having a 'positive MRI' as defined by Assessment of Spondyloarthritis International Society. Another study revealed that a substantial proportion of patients with suspected sacroiliitis were more commonly diagnosed with diseases other than inflammatory sacroiliitis. On the basis of these reports, it is prudent to request MRIs in the appropriate clinical context and interpreted with caution taking into considerations the wide differential diagnosis of such MRI changes. Highlighting the clinical pearls that differentiate disorders suspected of having sacroiliitis will lead to earlier and correct diagnosis and management; however, one must always take into considerations the radiographic and MRI findings in addition to the clinical presentations in order to make the appropriate diagnosis.

Prevalence of bone marrow edema in a study population with foot and/or ankle pain

Bone marrow edema (BME) is an imaging diagnosis defined by an abnormal accumulation of intraosseous interstitial fluid within a bone on magnetic resonance imaging (MRI) investigation. The aim of this study was to determine the prevalence of BME in patients with foot and/or ankle pain studied using MRI. This was a retrospective observational work on patient cases and controls studied through MRI of the foot and/or ankle at our Foot and Ankle Unit (FAU). An analytical statistical analysis and a multivariate analysis were performed to eliminate possible confounding factors. 1950 foot and/or ankle MRI cases were reviewed, of which 451 presented bone edema (23% prevalence). The average patient age was 51.8 (range, 7–87); the talus bone was most frequently affected: post-traumatic in 43.5% of cases, degenerative in 34.7% and there was no specific cause identified in 6.3% (these cases were termed ‘idiopathic’). With regards to risk factors, in the case of gender, the odds ratio (OR) of men suffering bone oedema was 1.5 times higher than that of women (P = 0.003); for immunosuppression the OR was 3.4 times higher (P = 0.001); while among those with a smoking habit it was 0.59 (P = 0.001), meaning that after ruling smoking out as a possible confounding factor, it was, in fact, revealed to be a protective factor. The prevalence of bone edema in MRI in patients with foot and/or ankle pain was 23%. The average patient was male, aged approximately 50, with traumatic or degenerative origin talus bone oedema.Level of Evidence: Level IV, revision observational study.

A Comprehensive Study of Bone Manifestations in Adult Gaucher Disease Type 1 Patients in Argentina.

Gaucher disease (GD) is the most prevalent lysosomal storage disease, and bone involvement is the most disabling condition. The aim of the present study was to evaluate bone involvement in adult patients with GD, using an observational cross-sectional study. Patients were evaluated using X-rays, bone densitometry (BMD), trabecular bone score (TBS), magnetic resonance imaging (MRI), and biochemical bone markers. Thirty-two type 1GD patients were included (mean age: 40 ± 16years). Patients had received velaglucerase for 2.7 ± 1.4years; 19/32 had been treated previously with imiglucerase. Ninety-four percent of subjects met therapeutic goals for hematological parameters, and eight were splenectomized (SPX). Nineteen patients had irreversible bone lesions (IL), i.e., avascular necrosis, bone infarction, and/or vertebral fractures. MRI showed marrow infiltration in 71% of patients. Patients with IL had higher bone marrow burden than those without (p = 0.001). All SPX patients had IL, a higher prevalence of bone marrow edema (p = 0.02), and lower TBS (p = 0.03) than non-SPX patients. Only 18.7% of patients had abnormal BMD, with no correlation with fractures (FX). TBS values were < 1350 in 53% of patients and tended to be lower in those with FX (p = 0.06). Patients with P1NP in the lower quartile had lower TBS (p = 0.03) than those with P1NP in the higher quartiles. TBS correlated moderately but not significantly with P1NP (r = 0.32) and BMB (r = - 0.44). A high prevalence of IL was documented. Bone quality was more affected than BMD in fracture patients. Low bone formation, active bone marrow infiltration, and splenectomy might be implicated in IL.

Differences in magnetic resonance findings between symptomatic and asymptomatic pre-collapse osteonecrosis of the femoral head

PurposeThe purpose of this study was to assess the differences in magnetic resonance (MR) findings between the symptomatic and asymptomatic pre-collapse stage of osteonecrosis of the femoral head (ONFH). Materials and methodsThis study reviewed 123 consecutive hips in 91 patients in the pre-collapse stage of ONFH based on plain radiographic findings. These 123 hips were divided into symptomatic and asymptomatic groups according to the pain domain score in the Harris hip score system. Bone marrow edema (BME), synovial fluid effusion, and subchondral fracture were evaluated using MR imaging. Odds ratios (ORs) were calculated between these three parameters and symptoms. The subsequent clinical course after MR examination was also assessed for each hip that could be followed more than 1 year. ResultsForty-six hips (37.4%) were categorized as symptomatic and 77 hips (62.6%) as asymptomatic. The prevalence of BME, synovial fluid effusion, and subchondral fracture were 87.0% (40/46), 80.4% (37/46), and 34.8% (16/46), respectively, in the symptomatic group, and 0%, 28.6% (22/77), and 0%, respectively, in the asymptomatic group, indicating significant differences between the two groups (p < 0.0001). Among these parameters, BME showed the highest OR with regard to the presence or absence of symptoms (BME, 965.8; joint effusion, 10.3; subchondral fracture, 83.9). Due to persistent pain and subsequent collapse, 30 of 35 (85.7%) symptomatic hips with BME subsequently underwent surgical treatment at a mean interval of 3.47 months after MR examination, while 25 of 66 (37.9%) asymptomatic hips without BME underwent surgical treatment at a mean interval of 20.7 months after MR examination. ConclusionsThis study demonstrated that symptomatic pre-collapse ONFH diagnosed based on plain radiographic findings could be distinguished from asymptomatic pre-collapse ONFH by the presence of BME on MR imaging, and thus BME may be a sign of occult fracture.

MRI of the knees in asymptomatic adolescent soccer players: A case-control study.

To determine the range of asymptomatic abnormal findings in adolescent soccer players at 3.0T MRI of the knee. In all, 87 knees of asymptomatic 14-17-year-old male adolescents were evaluated at 3T, using a standardized examination protocol comprising four sequences: two fat-suppressed T2 -weighted fast spin-echo sequences (T2 FSE), in the sagittal (repetition time / echo time [TR/TE], 5.300/71, echo train length [ETL] 17) and coronal planes (TR/TE, 4234/70, ETL 17), one fat-suppressed proton density (PD) sequence in the axial plane (TR/TE, 2.467/40, ETL 9), and one T1 -weighted spin-echo (T1 SE) sequence in the sagittal plane (TR/TE, 684/12.5). Soccer players (46 knees) were paired with controls (41 knees) by age and weight. Bone marrow, articular cartilage, meniscus, tendons, ligaments, fat pad abnormalities, and joint fluid were assessed. One or more abnormalities were detected in 31 knees (67.4%) in the soccer player group, compared to 20 knees (48.8%) in the control group. The prevalence of bone marrow edema was higher in the soccer group (19 knees, 41.3%) than in the control group (3 knees, 7.3%), P = 0.001. Other abnormalities found in this sample (joint effusion, cartilage lesions, tendinopathy, ganglion cysts, and infrapatellar fat pat edema) were not significantly different between the two study groups. Asymptomatic adolescents had a high prevalence of abnormal findings on knee imaging, especially bone marrow edema. This prevalence was higher among soccer players. 4 J. Magn. Reson. Imaging 2017;45:59-65.

Bone Marrow Edema and Low Back Pain in Elderly Degenerative Lumbar Scoliosis: A Cross-Sectional Study.

Cross-sectional study. To examine whether bone marrow edema is associated with low back pain in elderly patients with degenerative lumbar scoliosis. The cause of low back pain in degenerative lumbar scoliosis is unclear. A total of 120 degenerative lumbar scoliosis patients 65 years of age or older were evaluated. Radiography, computed tomography (CT), magnetic resonance imaging (MRI), and tender point examination in the lumbar spine were performed. On MRI, coronal gadolinium-contrasted T1- or T2-weighed fat-saturated images were used to score the size of bone marrow edema. The prevalence of bone marrow edema in patients with and without low back pain was compared; in patients with low back pain, we tested whether the locations of lumbar tender point were consistent with that of bone marrow edema. Bone marrow edema was found in 62 of 64 (96.9%) patients with low back pain compared with 21 of 56 (37.5%) patients without it (P < 0.001). Bone marrow edema located more frequently on the concave side than on the convex side of scoliosis (P < 0.001). Among patients with low back pain, bone marrow edema score was associated with low back pain severity (r = 0.724; P < 0.001), and the location of lumbar tender point were consistent with that of bone marrow edema (κ value = 0.745; P < 0.001). Bone marrow edema on MRI was closely associated with the presence of low back pain in elderly degenerative lumbar scoliosis. 4.

SAT0289 Mri assessment of spinal involvement in psoriatic arthritis: Extent of disease relates to HLA-B27

BackgroundPsoriatic Arthritis (PsA) is a heterogeneous disease with a variable, sometimes evolving clinical phenotype. An estimated 25-70% of patients may have spinal involvement which varies from largely asymptomatic to severe...

Effect of Accelerated Weightbearing after Matrix-Associated Autologous Chondrocyte Implantation on the Femoral Condyle on Radiographic and Clinical Outcome after 2 Years

Background There is no consensus about the optimal time for weightbearing activities after matrix-associated autologous chon-drocyte implantation (MACI) of the femoral condyle. Hypothesis A comprehensive protocol after MACI on the femoral condyle with accelerated weightbearing leads to a better functional and radiographic outcome compared with the same comprehensive protocol with delayed weightbearing. Study Design Randomized controlled trial; Level of evidence, 1. Methods Thirty-one patients (22 male, 9 female) after MACI on the femoral condyle were randomly assigned to the accelerated weightbearing group (group A) or the delayed weightbearing group (group B). Aside from increase and time of full weightbearing, both groups adhered to the same rehabilitation protocol and exercises. Patients were assessed preoperatively and at 4, 12, 24, 52, and 104 weeks after surgery. Clinical evaluation was performed by determining the subjective form of the International Knee Documentation Committee (IKDC), the Tegner activity scale, and the Knee Injury and Osteoarthritis Outcome Score (KOOS). Radiological outcome was evaluated by the MOCART score and the size and amount of bone marrow edema and effusion. Results In both groups, there were no differences with regard to the clinical outcome. For the radiological outcome, group A showed a higher prevalence of bone marrow edema after 6 months without correlation to the clinical outcome (P 5 .06-.1). However, after 104 weeks, there were no differences in the radiological outcome between group A and group B. Conclusion A rehabilitation protocol with accelerated weightbearing leads to good clinical and functional outcome after 2 years without jeopardizing the healing graft.

P252 The prevalence of bone marrow edema in sibling pairs with familial OA at multiple sites. The GARP study

P252 The prevalence of bone marrow edema in sibling pairs with familial OA at multiple sites. The GARP study

Bone marrow edema in the greater tuberosity of the humerus at MR imaging: association with rotator cuff tears and traumatic injury

The purpose of this study was to determine the prevalence of bone marrow edema in the greater tuberosity of the humerus on MR imaging, the association with other findings at MR imaging and the injury mechanism which can lead to this finding. Subjects and methods: MR reports from 863 patients referred for shoulder MRI over 74 months were reviewed to identify patients with marrow edema in the greater tuberosity. The MR images from patients with greater tuberosity marrow edema were reviewed by consensus of two radiologists for the extent of marrow edema and for associated injuries. Marrow edema in the greater tuberosity was seen in 11 of 863 patients (1.3%). Nine patients (82%) had associated rotator cuff tear by MR imaging (four full thickness and five partial thickness), one patient had avulsion of the greater tuberosity from the humerus, and one had no rotator cuff abnormality. History of trauma was reported by eight patients including fall without direct blow to the shoulder (6), car accident (1) and direct blow to the top of the shoulder (1). Marrow edema in the greater tuberosity is an infrequent finding. Marrow edema most often is associated with a history of trauma and with rotator cuff abnormalities including full thickness tears. The history of trauma without direct blow to the shoulder and the location of the edema indicates that marrow edema often results from avulsion injury by the supraspinatus tendon.