Assessment of postoperative acromial and subacromial morphology after arthroscopic acromioplasty using magnetic resonance imaging.

OBJECTIVE: To identify the morphological characteristics of the acromion and subacromial bursal space after arthroscopic acromioplasty using magnetic resonance imaging (MRI). MATERIALS AND METHODS: One hundred patients who received arthroscopic rotator cuff repair and acromioplasty each received at least three MRI examinations (preoperative, first immediate postoperative, and second follow-up imaging between 8 months and 1 year postoperatively). Changes over time in the thickness and morphology of the postoperative acromion as well as the subacromial bursal space were assessed. Clinical and radiological parameters were also analyzed to identify any association with changes in acromial morphology. RESULTS: Despite minimal acromial thinning observed at the first immediate postoperative state, the acromions showed significant thinning at the second postoperative MRI, with a mean reduction of 32%. Along with acromial thinning, an exaggerated concave contour of the acromial undersurface was observed in some patients. In the subacromial space, a loculated fluid collection developed in 91% of the patients at the second postoperative follow-up. No statistically significant association was noted between postoperative acromial thickness change and clinical or radiological factors (P value > 0.05). CONCLUSION: A significant delayed reduction in acromial thickness within approximately 1 year of arthroscopic acromioplasty is thought to be a normal postoperative feature. The simultaneous collection of a loculated, cyst-like fluid in the subacromial bursal space may be an important associated factor of postoperative acromial thinning.

The prevalence of Baker cyst in relation to the arrangement pattern between the medial head of gastrocnemius tendon and the semimembranosus tendon.

PURPOSE: The purpose of this study was to investigate whether Baker cyst (BC) was related to the specific arrangement of the medial head of gastrocnemius tendon (MHGT) and the semimembranosus tendon (SMT). MATERIALS AND METHODS: Patients who underwent knee MRI with "Baker cyst" in PACS from August 2017 to February 2018 were included in this study. Patients who did not have BC in a knee MRI performed during the same period were included in the control group. A total 210 patients were selected for inclusion in this study. For the imaging analysis, the arrangement pattern between MHGT and SMT was classified into three types: type 1, concave; type 2, flat; and type 3, convex. When imaging analysis was performed, the amount of effusion, the presence of osteoarthritis, and major ligament and meniscal tears were also described. Univariate and multivariate logistic regression analyses were performed. Statistical significance was considered at p < 0.05. RESULTS: The frequency of types 1, 2, and 3 was statistically significant depending on the presence or absence of BC (p < 0.001). The frequency of type 3 was the highest in the presence of BC, while that of type 1 was the highest in the absence of BC. BC was more common in type 2 (OR = 2.54; 95% CI = 1.27-5.07) and type 3 (OR = 4.09; 95% CI = 1.88-8.89). CONCLUSION: BC is more likely to occur in patients with SMT having a convex shape for MHGT. KEY POINTS: • Based on axial image of MRI only, one can predict which patients are morphologically more prone to develop a Baker cyst. • On axial images of MRI, Baker cyst is more likely to occur in patients with semimembranosus tendon having a convex shape for medial head of gastrocnemius tendon. • Baker cyst is not associated with the amount of effusion, OA, or internal derangement.

Systematic review and meta-analysis of magnetic resonance imaging features for diagnosis of adhesive capsulitis of the shoulder.

OBJECTIVES: To perform a systematic review and meta-analysis to identify magnetic resonance imaging (MRI) features that will aid in the diagnosis of adhesive capsulitis of the shoulder (ACS) and provide a summary of the diagnostic accuracy of the identified features METHODS: The MEDLINE and EMBASE databases were searched for studies assessing the diagnostic accuracy of MRI features of ACS. Overlapping descriptors used to denote the same imaging finding in different studies were subsumed under a single feature. The pooled accuracy including the diagnostic odd ratios (DORs) with 95% confidence intervals (CIs) of the identified features was calculated using a bivariate random-effects model. RESULTS: In total, 15 studies were included, and 74 overlapping descriptors were subsumed under six features. All six features were found to be informative for ACS diagnosis [coracohumeral ligament thickening: DOR, 13; 95% CI, 6-29; fat obliteration of the rotator interval (RI): DOR, 8; 95% CI, 3-24; RI enhancement: DOR, 44; 95% CI, 14-141; axillary joint capsule enhancement: DOR, 52; 95% CI, 27-98; inferior glenohumeral ligament (IGHL) hyperintensity: DOR, 31; 95% CI, 8-115; IGHL thickening: DOR, 28; 95% CI, 11-70]. The sensitivity and specificity of enhancement of the RI and axillary joint capsule and IGHL hyperintensity were > 80%. CONCLUSIONS: Six informative MRI features for ACS diagnosis were identified in this study with RI and axillary joint capsule enhancement and IGHL hyperintensity showing the highest diagnostic accuracy. Informative features observed on non-arthrogram MRI can be as helpful as features observed on direct magnetic resonance arthrography for ACS diagnosis. KEY POINTS: • Six informative MRI features for ACS diagnosis were identified (diagnostic odds ratio > 1). • RI and axillary joint capsule enhancement and IGHL hyperintensity showed high sensitivities/specificities (> 80%). • The use of non-arthrogram MRI is recommended for ACS diagnosis.

Comparison between 3D isotropic and 2D conventional MR arthrography for diagnosing rotator cuff tear and labral lesions: A meta-analysis.

BACKGROUND: Although 3D-isotropic MR arthrography has been characterized as a substitute imaging tool for rotator cuff tear (RCT) and labral lesions, it has not been commonly used in clinical practice because of controversy related to image blurring and indistinctness of structural edges. PURPOSE: To perform a comparison of the diagnostic performance of 3D-isotropic MR arthrography and 2D-conventional MR arthrography for diagnosis of RCT (solely RCT, full/partial-thickness supraspinatus [SST]-infraspinatus [IST] tear, or subscapularis [SSc] tear) and labral lesions. STUDY TYPE: Meta-analysis. POPULATION: Patients with shoulder pain. FIELD STRENGTH/SEQUENCE: 3D-isotropic and 2D-conventional MR arthrography at 3.0T or 1.5T. ASSESSMENT: PubMed and EMBASE were searched following the PRISMA guidelines. STATISTICAL TESTS: Bivariate modeling and hierarchical summary receiver operating characteristic modeling were performed to compare the overall diagnostic performance of 3D-isotropic and 2D-conventional MR arthrography. Multiple-subgroup analyses were performed for diagnosing RCT, full/partial-thickness SST-IST tear, SSc tear, and labral lesions. Meta-regression analyses were performed according to subject, study, and MR arthrography characteristics including 3D-isotropic sequences (turbo spine echo [TSE] vs. gradient echo [GRE]). RESULTS: Eleven studies (825 patients) were included. Overall, 3D-isotropic MR arthrography had similar pooled sensitivity (0.90 [95% CI, 0.87-0.93]) (P = 0.95) and specificity (0.92 [95% CI, 0.87-0.95]) (P = 0.99), relative to 2D-conventional MR arthrography (sensitivity, 0.91 [95% CI, 0.86-0.94]); specificity, 0.92 [95% CI, 0.87-0.95]). Multiple-subgroup analyses showed that sensitivities (P = 0.13-0.91) and specificities (P = 0.26-0.99) on 3D-isotropic MR arthrography for diagnosing RCT, full/partial-thickness SST-IST tear, SSC tear, and labral lesions were not significantly different from 2D-conventional MR arthrography. On meta-regression analysis, 3D-TSE sequence demonstrated higher sensitivity (P < 0.01) than 3D-GRE for RCT and labral lesions. DATA CONCLUSION: 3D-isotropic MR arthrography can replace 2D-conventional MR arthrography. 3D-isotropic MR arthrography using TSE sequence is recommended for more accurate diagnosis, as it demonstrates increased sensitivity. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;48:1034-1045.

Efficacy of double inversion recovery magnetic resonance imaging for the evaluation of the synovium in the femoro-patellar joint without contrast enhancement.

OBJECTIVE: To investigate the efficacy of double inversion recovery (DIR) sequence for evaluating the synovium of the femoro-patellar joint without contrast enhancement (CE). METHODS: Two radiologists independently evaluated the axial DIR and CE T1-weighted fat-saturated (CET1FS) images of 33 knees for agreement; the visualisation and distribution of the synovium were evaluated using a four-point visual scaling system at each of the five levels of the femoro-patellar joint and the location of the thickest synovium. The maximal synovial thickness at each sequence was measured by consensus. RESULTS: The interobserver agreement was good (κ = 0.736) for the four-point scale, and was excellent for the location of the thickest synovium on DIR and CET1FS (κ = 0.955 and 0.954). The intersequential agreement for the area with the thickest synovium was also excellent (κ = 0.845 and κ = 0.828). The synovial thickness on each sequence showed excellent correlation (r = 0.872). CONCLUSION: The DIR showed as good a correlation as CET1FS for the evaluation of the synovium at the femoro-patellar joint. DIR may be a useful MR technique for evaluating the synovium without CE. KEY POINTS: • DIR can be useful for evaluating the synovium of the femoro-patellar joint. • Interobserver and intersequential agreements between DIR and CET1FS were good. • Mean thickness of the synovium was significantly different between two sequences.

Predictive Factors of Retear in Patients With Repaired Rotator Cuff Tear on Shoulder MRI.

OBJECTIVE: This study aimed to find independent prognostic factors related to retear of the rotator cuff tendon in patients with repaired full-thickness supraspinatus tendon tear by evaluation of pre- and postoperative MR images. MATERIALS AND METHODS: Shoulder MR images were retrospectively analyzed for 83 patients who had undergone arthroscopic or open rotator cuff repair with acromioplasty for full-thickness supraspinatus tendon tear from April 2014 to March 2015. On preoperative MR images, the type of rotator cuff tear, extent of retraction of torn tendon, anteroposterior (AP) dimension of torn tendon, signal intensity of tear edge, degree of fat infiltration in supraspinatus and infraspinatus muscles, and acromiohumeral interval (AHI) were assessed. Postoperative cuff integrity seen on MR images was classified into five categories according to the Sugaya classification system, and patients were categorized into retear or intact groups. Factors assessed on preoperative MR images were compared between the two groups. RESULTS: The overall retear rate was 57.8%. Significant differences were observed between the retear and intact groups in terms of the mean values of the extent of tendon retraction (20.4 vs 11.7 mm), AP dimension of the tear (16.1 vs 11.4 mm), AHI (6.8 vs 8.7 mm), and degree of fat infiltration of the supraspinatus and infraspinatus muscles (for the supraspinatus muscle, 3, 30, and 15 patients in the retear group vs 5, 27, and three patients in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively; for the infraspinatus muscle, 27, 12, and 9 patients in the retear group vs 29, 5, and one patient in the intact group had Goutallier grade 1, grade 2, and grades 3 and 4 infiltration, respectively). Multivariable analysis revealed that AHI and degree of tendon retraction were independent predictive factors affecting retear of rotator cuff after repair. CONCLUSION: The retear rate of repaired rotator cuff tendon was about 57.8%. Independent prognostic factors of retear were degree of tendon retraction and AHI on preoperative MR images.

Validity of Radiograph-Based Infrapatellar Fat Pad Opacity Grading for Assessing Knee Synovitis: Correlation With Contrast-Enhanced MRI.

OBJECTIVE: The purpose of this study was to determine the validity of infrapatellar fat pad (IPFP) opacity grading based on lateral knee radiography for assessing knee synovitis using correlation with contrast-enhanced (CE) MRI. MATERIALS AND METHODS: Retrospective reviews of radiographs and CE knee MR images from 79 patients were independently performed by two radiologists. They evaluated IPFP opacity alteration (IPFPCR) and joint effusion grades on lateral knee conventional radiographs, IPFP signal intensity alteration (IPFPMR) and joint effusion grades on CE MR images, and synovitis (SYNMR) grade in nine divided regions, three compartments (parapatellar, periligamentous, perimeniscal), and the whole knee on CE MR images. Correlations between radiographic grades and MRI assessments were evaluated using Spearman correlation tests, and the correlation coefficients (ρ) were compared. Interobserver agreement was evaluated using weighted kappa values. RESULTS: The IPFPCR grade was very highly correlated with the IPFPMR grade (ρ = 0.906, p < 0.001) and highly correlated with SYNMR grades from four regions (suprapatellar, infrapatellar, intercondylar, lateral parapatellar recess), the parapatellar compartment, and the whole knee (ρ = 0.614-0.740, all p < 0.001). The IPFPCR grade was moderately correlated with the SYNMR grades of the remaining five regions and two compartments (ρ = 0.457-0.547, all p < 0.001). The differences between correlation coefficients for SYNMR grades and the IPFPCR and IPFPMR grades were not statistically significant (p = 0.290-1.0). Interobserver reliabilities were excellent or good for IPFPCR, IPFPMR, and SYNMR grades (κ = 0.661-1.000). CONCLUSION: IPFPCR grade assessment enables valid evaluation and reporting of knee synovitis, especially in the parapatellar compartment and the whole knee.

A Focal Defect at the Lateral Patellar Retinaculum on Clinical Knee MRI and Cadaveric Study: A Normal Variant or Pathologic Lesion?

OBJECTIVE: The purpose of this study is to retrospectively investigate the frequency of a focal defect at the lateral patellar retinaculum on knee MRI and to determine the variables that are significantly associated with the defect. MATERIALS AND METHODS: Two radiologists independently reviewed 99 knee MR images for the presence of a focal defect at the lateral patellar retinaculum and categorized patients with concordant results into two groups: a group with the defect (≥ 3 mm; group 1) and a group without the defect (< 3 mm; group 2). Clinical and radiologic variables, including the Kellgren-Lawrence radiographic grade, subcutaneous fat thickness, infrapatellar fat pad area, and the amount of joint effusion, were evaluated. The size and location of the defect were measured in group 1. To correlate MRI and histologic findings, MRI was performed for 11 cadavers, and three histologic specimens were obtained. RESULTS: Of the 99 knee MR images, concordant results between two reviewers were obtained for a total of 96 knees (97%): 25 knees (26%) in group 1 and 71 knees (74%) in group 2. A statistically significant difference between groups (p = 0.033) was noted for the infrapatellar fat pad area only. In all three cadaveric specimens, the lateral patellar retinaculum was more loose and sparse than the medial patellar retinaculum, and this site corresponded to the location of the defect on MRI. CONCLUSION: A focal defect of the lateral patellar retinaculum was not found to be a rare finding on knee MRI (frequency, 26%), and it may be a normal variant rather than a pathologic change. In addition, we suspect that a focal defect can be a route of infrapatellar fat herniation and a route of superficial extension of the infrapatellar fat pad lesion without a lateral patellar retinaculum tear or invasion.

Bilateral bony fusion around the supraspinatus muscle inducing muscle hypoplasia and shoulder pain.

We describe the case of a 30-year-old man who developed chronic bilateral shoulder pain that relapsed and remitted over the course of 1 year. The patient was diagnosed with congenital shoulder fusion anomalies. The right shoulder showed anomalous accessory articulation between the distal third of the clavicle and the acromion along with normal articulation of the shoulder on CT. At the left shoulder, bony fusions were present between the distal portion of the clavicle, the acromion, and the coracoid process, and between the coracoid process, upper portion of the glenoid, and upper body of the scapula, which formed a bony canal and was responsible for hypoplasia of the supraspinatus muscle on CT and MRI. To our knowledge, this is the first description of such congenital shoulder anomalies with extreme bony fusion and is an illustrative example of how imaging may be used to differentiate fusion from other congenital abnormalities of the shoulder to aid diagnosis.

Optimal Duration of Antibiotic Therapy in Patients With Hematogenous Vertebral Osteomyelitis at Low Risk and High Risk of Recurrence.

BACKGROUND: The optimal duration of antibiotic treatment for hematogenous vertebral osteomyelitis (HVO) should be based on the patient's risk of recurrence, but it is not well established. METHODS: A retrospective review was conducted to evaluate the optimal duration of antibiotic treatment in patients with HVO at low and high risk of recurrence. Patients with at least 1 independent baseline risk factor for recurrence, determined by multivariable analysis, were considered as high risk and those with no risk factor as low risk. RESULTS: A total of 314 patients with microbiologically diagnosed HVO were evaluable for recurrence. In multivariable analysis, methicillin-resistant Staphylococcus aureus infection (adjusted odds ratio [aOR], 2.61; 95% confidence interval [CI], 1.16-5.87), undrained paravertebral/psoas abscesses (aOR, 4.09; 95% CI, 1.82-9.19), and end-stage renal disease (aOR, 6.58; 95% CI, 1.63-26.54) were independent baseline risk factors for recurrence. Therefore, 191 (60.8%) patients were classified as low risk and 123 (39.2%) as high risk. Among high-risk patients, there was a significant decreasing trend for recurrence according to total duration of antibiotic therapy: 34.8% (4-6 weeks [28-41 days]), 29.6% (6-8 weeks [42-55 days]), and 9.6% (≥8 weeks [≥56 days]) (P = .002). For low-risk patients, this association was still significant but the recurrence rates were much lower: 12.0% (4-6 weeks), 6.3% (6-8 weeks), and 2.2% (≥8 weeks) (P = .02). CONCLUSIONS: Antibiotic therapy of prolonged duration (≥8 weeks) should be given to patients with HVO at high risk of recurrence. For low-risk patients, a shorter duration (6-8 weeks) of pathogen-directed antibiotic therapy may be sufficient.

Diagnostic performance of abdominal CT for diagnosis of pelvic fractures: comparison with pelvic CT.

BACKGROUND: In the emergency department, patients with abdominopelvic trauma inadvertently undergo both abdominal computed tomography (CT) (for intra-abdominal and intra-pelvic organs) and pelvic CT (CT with multiplanar reformation in three orthogonal planes of the bony pelvis). However, the systemic use of CT is concerning given the cumulative radiation dose. PURPOSE: To evaluate the diagnostic value of abdominal CT in comparison to pelvic CT in patients with suspected pelvic fractures. MATERIAL AND METHODS: Seventy-two patients who underwent abdominal CT and pelvic CT within a 2-week period to evaluate pelvic fractures were included. Two reviewers retrospectively analyzed eight anatomical regions of the pelvic bones on both abdominal CT and pelvic CT over a 1-week interval. The interpretation of pelvic CT scans by two senior musculoskeletal radiologists was considered as the reference standard. Diagnostic performance and inter-observer agreement of both CT scans were evaluated. RESULTS: For reviewers 1 and 2, abdominal CT showed high accuracy (98% and 98%, respectively) as did pelvic CT. For both abdominal CT and pelvic CT, fracture detection in all anatomical regions of the pelvic bones was not significantly different for the two reviewers (P ≥ 0.25). Inter-observer agreement for all anatomical regions of the pelvic bones was excellent or good (k = 0.785-1.0). CONCLUSION: Not only pelvic CT but also abdominal CT is acceptable for detection of pelvic fractures, in spite of its thicker sections and different reconstruction algorithm. Therefore, if abdominal CT has already been performed, additional pelvic CT might no longer be necessary in order to exclude a pelvic fracture.

Invagination of intra-abdominal structures in the lumbar intervertebral disc space.

Invagination of peritoneal or retroperitoneal structures into the intervertebral disc space of the lumbar spine is extremely rare. In this article the imaging features and clinical findings are demonstrated in four patients with intervertebral invagination of intra-abdominal structures. Plain radiographs, CT scans, and MR images showed disruption of the anterior ligamentous complex (ALC) and invagination of various structures into the disc space, including the vena cava, iliac vessels, intestine, the torn redundant anterior longitudinal ligament, retroperitoneal fat, and the psoas muscle. The invaginations occurred at the level of L3-L4 and L4-L5 in one case each and at L5-S1 in two cases. Follow-up imaging in three cases (1, 5, and 8 years respectively) showed the progression of the invagination. These cases demonstrate that a close evaluation of this condition is necessary, particularly for older patients who show disruption or laxity of the ALC, degenerative spondylosis with chronic segmental instability, and osteoporosis of the lower lumbar spine.

Therapeutic outcomes of hematogenous vertebral osteomyelitis with instrumented surgery.

BACKGROUND: Patients with hematogenous vertebral osteomyelitis (HVO) occasionally require instrumentation for spinal stabilization. However, placing instrumentation in the setting of spinal infection raises concerns about recurrent infection due to bacteria adhering to the foreign material. In this study, we evaluated the therapeutic outcomes of patients with HVO who underwent instrumented surgery. METHODS: We conducted a retrospective chart review of adult patients with microbiologically diagnosed HVO who underwent surgical intervention in 5 tertiary care hospitals over an 8-year period. RESULTS: A total of 153 patients with HVO underwent surgical management for their infections. Of these 153 patients, 94 (61.4%) underwent surgical debridement alone (noninstrumented surgery) and 59 (38.6%) underwent surgical debridement and instrumentation (instrumented surgery). The median durations of antibiotic therapy were 66 and 80 days for the noninstrumentation and instrumentation groups, respectively (P = .22). Clinical outcomes were similar between the groups, including rates of infection-related death (2.1% vs 0%; P = .52), primary failure (1.1% vs 5.1%; P = .30), and recurrence (4.8% vs 6.8%; P = .72). Among the instrumentation group, there was a significant decreasing trend for recurrence according to total duration of antibiotic therapy: 22.2% (4-6 weeks), 9.1% (6-8 weeks), and 2.6% (≥ 8 weeks; P = .04). Duration of pre-instrumentation antibiotic therapy and single-stage operation (vs 2-stage operation) were not risk factors for recurrence. CONCLUSIONS: Spinal instrumentation in patients with HVO may be safe with pathogen-directed prolonged antibiotic therapy and should not be abandoned or delayed solely because of the risk of recurrence.

Increased signal intensity at the proximal patellar tendon: correlation between MR imaging and histology in eight cadavers and clinical MR imaging studies.

OBJECTIVES: We set out to investigate the cause of persistently increased signal intensity (SI) in the posterior portion of the proximal patellar tendon (pPT) on T1-weighted images (T1WI). METHODS: MR imaging was performed in eight cadavers, followed by gross histological examination. In addition, 84 patients without trauma history or anterior knee pain were included to compare the SI of the PTs. The patients were divided according to their age, sex, and Kellgren-Lawrence (KL) grades. The length and thickness of the increased SI portion in the pPT and whole PT (wPT) on T1WI were recorded. RESULTS: Histological specimens demonstrated that the adipose tissue, vessels, and perivascular connective tissue invaginated into the posterior portion of the pPT. This histological anatomy corresponded to the pPT signal change on MR imaging. There was linear and interdigitating increased SI of the pPT in all of the 84 patients (100%). There were no differences in the lengths and thicknesses of the increased SI portion of pPTs and wPTs according to age, sex, and KL grade (all p > 0.05). CONCLUSIONS: The increased SI of the pPT on T1WI and fluid-sensitive MR images results from invaginating fat, vessels, and perivascular connective tissue. It is not pathological, but a normal and common finding. KEY POINTS: • Increased linear/interdigitated SIs of the pPT is a normal and common finding. • Invaginated adipose tissue, vessels, and connective tissue could contribute to increased SI. • The fibrocartilage has a minimal role in increased SI of the pPT. • Age, sex, and KL grade do not significantly influence the increased SI. • Knowledge of this increased SI should help clinicians to avoid unnecessary treatment.

A Different Type of Talocalcaneal Coalition With Os Sustentaculum: The Continued Necessity of Revision of Classification.

OBJECTIVE: The objective of our study was to retrospectively determine the prevalence and image findings of extraarticular talocalcaneal coalition with os sustentaculum, a type of talocalcaneal coalition that does not appear in current classification systems, in patients with an imaging diagnosis of foot coalition. MATERIALS AND METHODS: This study was performed using a database query of radiology reports of ankle and foot CT or MRI examinations performed from August 2001 to November 2013. Eighty-one patients were identified through a keyword search of the database for "talocalcaneal coalition," "tarsal coalition," "coalition," or "os sustentaculum." Imaging features of CT or MRI findings were evaluated. Chart review was used to identify demographic information. RESULTS: Extraarticular talocalcaneal coalition with os sustentaculum was diagnosed in 13 patients (nine men, four women), which represents a prevalence of 16.0% (13/81) in all foot coalitions and 24.1% (13/54) in all talocalcaneal coalitions. Four of 13 patients underwent surgical resection, and histology was obtained in three patients. Nine patients who had no history of trauma were symptomatic and all patients with bone marrow edema at the coalition sites on MRI (n = 5) were also symptomatic. Coexisting extraarticular talocalcaneal coalition with os sustentaculum and intraarticular talocalcaneal coalition were observed in 11 of 13 patients. CONCLUSION: The os sustentaculum is a component of extraarticular talocalcaneal coalitions and as such is usually related to the presence of symptoms. If a patient with an os sustentaculum has symptoms in the medial talocalcaneal joint area, an extraarticular talocalcaneal coalition related to the os sustentaculum should be considered.

Sonographic Features of Superficial-Type Nodular Fasciitis in the Musculoskeletal System.

OBJECTIVES: We evaluated the sonographic features of superficial-type nodular fasciitis in 9 pathologically proven cases. METHODS: Review of the radiology and pathology databases yielded 14 cases of histologically proven superficial-type nodular fasciitis, which was defined as nodular fasciitis located in the subcutaneous fat layer or outer muscle fascia between the subcutaneous fat layer and muscle. Sonograms were available in 9 patients. Two musculoskeletal radiologists retrospectively reviewed all cases in consensus. Imaging features evaluated included the fasciitis location in the body, size, relationship with the fascia, echogenicity, vascularity, and location of the center. RESULTS: There were 4 male and 5 female patients. The mean age was 35 years (range, 8-49 years). The masses ranged in size from 0.8 to 2 cm, with 90% measuring less than 1.8 cm. Five masses developed in the forearm (4 cases) or elbow (1 case). Six masses were located in the subcutaneous fat layer, and 3 masses were in the fascia. Seven masses were in direct contact with the outer muscle fascia, whereas 2 masses were indistinctly in contact with the fascia. These masses showed a hypoechoic background with echogenic foci or peripheral hyperechoic nodules. In all 3 of the masses within the fascia, the findings were similar to those of neurogenic tumors. The vascularity of the masses was variable, but most (7 of 9 cases) showed no substantial vascularity. All masses had centers of less than half the thickness of the subcutaneous fat layer. CONCLUSIONS: Superficial-type nodular fasciitis is often located in the deep subcutaneous fat near the muscle fascia, has a hypoechoic appearance with echogenic foci or peripheral hyperechoic nodules, and quite often does not show internal vascular flow. If a superficial soft tissue mass has the above findings, superficial-type nodular fasciitis should be included in the differential diagnosis.

The tram track sign: a characteristic sonographic feature of polyethylene liner dissociation after total-hip arthroplasty.

OBJECTIVES: Polyethylene liner dissociation from an acetabular component is a complication of total-hip arthroplasty (THA) caused by slippage of the liner, which causes pain and requires a revision. The aim of this study was to evaluate sonographic features of liner dissociation and detect useful sonographic findings compared to conventional radiography and computed tomography (CT). METHODS: Among a total of 226 patients who underwent revision THA at our institution between September 2008 and June 2012, 10 patients (6 male and 4 female; mean age, 56.2 years) who showed severe narrowing of the superior joint space on the THA side and underwent sonography were retrospectively reviewed by evaluating radiographic, CT, and sonographic findings. In evaluation of the images, we put more emphasis on the "radiographic crescent sign," "CT crescent sign," and "sonographic tram track sign." RESULTS: At surgery, 7 patients showed liner dissociation, and 3 showed severe liner wear. On radiography, 8 of 10 patients (80%) had a correct diagnosis of the presence or absence of liner dissociation; on sonography, all 10 patients (100%) had a correct diagnosis. The sensitivity, specificity, and accuracy for diagnosis of liner dissociation by pelvic radiography and sonography were 100% (7 of 7), 33% (1 of 3), and 80% (8 of 10) and 100% (7 of 7), 100% (3 of 3), and 100% (10 of 10), respectively. CONCLUSIONS: Liner dissociation can be easily and well visualized by sonography, especially compared to pelvic radiography and CT. The sonographic tram track sign should be a very useful feature in the early diagnosis of liner dissociation.

Sonographic appearance of a cartilaginous cyst from the symphysis pubis mimicking a mass in the urinary bladder.

A suprapubic cartilaginous cyst from the symphysis pubis is a rare lesion, which may be asymptomatic or cause symptoms such as urinary retention and pelvic pain. It is thought to be secondary to degenerative changes in the symphysis pubis and usually occurs in multiparous women. We report the case of a suprapubic cartilaginous cyst in a 76-year-old asymptomatic woman, which mimicked a bladder mass on ultrasonography.

Intravenous lobular capillary hemangioma occurring in the cephalic vein of a 39-year-old adult.

Intravenous lobular capillary hemangiomas are extremely uncommon and mostly occur in the veins of the neck and upper extremities. Here, we report the clinical and sonographic features of an intravenous lobular capillary hemangioma localized in the right cephalic vein, and we discuss its pathologic findings and differential diagnoses.