Preferential involvement of the pelvis and hips along with active sacroiliitis in chronic nonbacterial osteomyelitis: MRI of 97 patients from a single tertiary referral center.

OBJECTIVE: To present MRI distribution of active osteitis in a single tertiary referral center cohort of patients with chronic nonbacterial osteomyelitis (CNO). METHODS: Two musculoskeletal radiologists retrospectively reviewed MRI examinations of all patients with a final clinical diagnosis of CNO over 15 years. Sites of active osteitis at any time during the course of disease were divided into seven groups: (A) mandible, sternum, clavicles, or scapulas; (B) upper extremities; (C) subchondral sacrum and ilium immediately subjacent to sacroiliac joints (active osteitis denoting "active sacroiliitis" here); (D) pelvis and proximal 1/3 of femurs (excluding group C); (E) bones surrounding knees including distal 2/3 of femurs and 1/2 of proximal tibias and fibulas; (F) distal legs (including distal 1/2 of tibias and fibulas), ankles, or feet; (G) spine (excluding group C). Temporal changes of lesions in response to treatment (or other treatment-related changes such as pamidronate lines) were not within the scope of the study. RESULTS: Among 97 CNO patients (53 males [55%], 44 females; age at onset, mean ± SD, 8.5 ± 3.2 years; age at diagnosis, 10.3 ± 3.3 years), whole-body (WB) MRI was performed in 92%, mostly following an initial targeted MRI (94%). A total of 557 (346 targeted and 211 WB) MRIs were analyzed. Biopsy was obtained in 39 patients (40%), all consistent with CNO or featuring supporting findings. The most common locations for active osteitis were groups D (78%; 95% CI 69‒85%) and C (72%; 95% CI 62‒80%). CONCLUSION: Pelvis and hips were preferentially involved in this cohort of CNO patients along with a marked presence of active sacroiliitis. CLINICAL RELEVANCE STATEMENT: When suggestive findings of CNO are identified elsewhere in the body, the next targeted site of MRI should be the pelvis (entirely including sacroiliac joints) and hips, if whole-body MRI is not available or feasible. KEY POINTS: • Heavy reliance on MRI for diagnosis of CNO underscores the importance of suggestive distribution patterns. • Pelvis and hips are the most common (78%) sites of CNO involvement along with active sacroiliitis (72%). • Pelvis including sacroiliac joints and hips should be targeted on MRI when CNO is suspected.

Glenoid Track Assessment at Imaging in Anterior Shoulder Instability: Rationale and Step-by-Step Guide.

Anterior shoulder dislocation is the most common form of joint instability in humans, usually resulting in soft-tissue injury to the glenohumeral capsuloligamentous and labral structures. Bipolar bone lesions in the form of fractures of the anterior glenoid rim and posterolateral humeral head are often associated with anterior shoulder dislocation and can be a cause or result of recurrent dislocations. Glenoid track assessment is an evolving concept that incorporates the pathomechanics of anterior shoulder instability into its management. Currently widely endorsed by orthopedic surgeons, this concept has ramifications for prognostication, treatment planning, and outcome assessment of anterior shoulder dislocation. The glenoid track is the contact zone between the humeral head and glenoid during shoulder motion from the neutral position to abduction and external rotation. Two key determinants of on-track or off-track status of a Hill-Sachs lesion (HSL) are the glenoid track width (GTW) and Hill-Sachs interval (HSI). If the GTW is less than the HSI, an HSL is off track. If the GTW is greater than the HSI, an HSL is on track. The authors focus on the rationale behind the glenoid track concept and explain stepwise assessment of the glenoid track at CT or MRI. Off-track to on-track conversion is a primary goal in stabilizing the shoulder with anterior instability. The key role that imaging plays in glenoid track assessment warrants radiologists' recognition of this concept along with its challenges and pitfalls and the production of relevant and actionable radiology reports for orthopedic surgeons-to the ultimate benefit of patients. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Imaging in crush injury: a spectrum of findings in survivors of the twin earthquakes on February 6, 2023.

On February 6, two major earthquakes with magnitudes of 7.8 and 7.7 on the Richter scale hit Turkey and Northern Syria causing more than 50,000 deaths. In the immediate aftermath of the earthquakes, our major tertiary medical referral center received dozens of cases of crush syndrome, presenting with a variety of imaging findings. Crush syndrome is characterized by hypovolemia, hyperkalemia, and myoglobinuria that can lead to rapid death of victims, despite their survival of staying under wreckage for days. The typical triad of crush syndrome consists of the acute tubular necrosis, paralytic ileus, and third-space edema. In this article, we focus primarily on characteristic imaging findings of earthquake-related crush syndrome and divided them into two distinct subsections: myonecrosis, rapid hypovolemia, excessive third-space edema, acute tubular necrosis, and paralytic ileus, which are directly related to crush syndrome, and typical accompanying findings of earthquake-related crush syndrome. Lower extremity compression in earthquake survivors results in the typical third-space edema. In addition to the lower extremities, other skeletal muscle regions are also affected, especially rotator muscles, trapezius, and pectoral muscles. Although it may be relatively easy to better detect myonecrosis with contrast-enhanced CT scans, changing the windowing of the images may be helpful.

Different Attenuation Models of Diffusion-Weighted MR Imaging for the Differentiation of Benign and Malignant Musculoskeletal Tumors.

BACKGROUND: Several functional imaging techniques, including monoexponential diffusion-weighted imaging (m-DWI), intravoxel incoherent motion (IVIM), and diffusion kurtosis (DK) imaging, have been used in differentiating benign and malignant musculoskeletal tumors. Combining all three techniques in the same study population may improve differentiation. PURPOSE: To compare the diagnostic performance of m-DWI, IVIM, and DK models and their combinations in differentiating benign and malignant musculoskeletal tumors. STUDY TYPE: Prospective. POPULATION: Fifty patients with benign and malignant musculoskeletal tumors divided into nonmyxoid and nonchondroid and myxoid and/or chondroid subgroups. FIELD STRENGTH/SEQUENCE: A 1.5 T/m-DWI, IVIM, and DK single-shot spin-echo echo-planar sequences. ASSESSMENT: Minimum and volumetric values of apparent diffusion coefficient (ADC), pure molecular diffusion (Divim ), pseudodiffusion (D*), perfusion fraction (f), diffusion coefficient for kurtosis model (DK ), and Kurtosis (K) were compared between all benign and malignant tumors. Subgroup analysis was also performed for nonmyxoid and nonchondroid and myxoid and/or chondroid tumors. STATISTICAL TESTS: Independent samples t-test, Mann-Whitney U test, intraclass correlation coefficient, ROC analysis, and logistic regression analysis. A P value < 0.05 was considered statistically significant. RESULTS: ADCmin , Divim-min , D*vol , DK-min, Kvol, and Kmin values showed statistically significant differences between all benign and malignant tumors and nonmyxoid and nonchondroid tumor subgroup. Kmin showed the highest diagnostic performance in differentiating benign and malignant tumors with AUCs of 0.760 for "all tumors" and 0.825 for the nonmyxoid and nonchondroid tumor subgroup. No significant differences were detected in m-DWI-, IVIM-, and DK-derived parameters for differentiating benign and malignant myxoid and/or chondroid tumors. Only three of 63 combinations of prediction models demonstrated a higher diagnostic performance than Kmin ; however, improvements were not significantly different. DATA CONCLUSION: ADCmin , Divim-min , D*vol , DK-min , Kvol , and Kmin values can be used to differentiate benign and malignant musculoskeletal tumors. Our findings suggest that the added value of multiparametric approach in such differentiation is not significant. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Machine learning identifies factors related to early joint space narrowing in dysplastic and non-dysplastic hips.

OBJECTIVES: To utilise machine learning, unsupervised clustering and multivariate modelling in order to predict severe early joint space narrowing (JSN) from anatomical hip parameters while identifying factors related to joint space width (JSW) in dysplastic and non-dysplastic hips. METHODS: A total of 507 hip CT examinations of patients 20-55 years old were retrospectively examined, and JSW, center-edge (CE) angle, alpha angle, anterior acetabular sector angle (AASA), and neck-shaft angle (NSA) were recorded. Dysplasia and severe JSN were defined with CE angle < 25o and JSW< 2 mm, respectively. A random forest classifier was developed to predict severe JSN based on anatomical and demographical data. Multivariate linear regression and two-step unsupervised clustering were performed to identify factors linked to JSW. RESULTS: In dysplastic hips, lateral or anterior undercoverage alone was not correlated to JSN. AASA (p < 0.005) and CE angle (p < 0.032) were the only factors significantly correlated with JSN in dysplastic hips. In non-dysplastic hips, JSW was inversely correlated to CE angle, AASA, and age and positively correlated to NSA (p < 0.001). A random forest classifier predicted severe JSN (AUC 69.9%, 95%CI 47.9-91.8%). TwoStep cluster modelling identified two distinct patient clusters one with low and one with normal JSW and different anatomical characteristics. CONCLUSION: Machine learning predicted severe JSN and identified population characteristics related to normal and abnormal joint space width. Dysplasia in one plane was found to be insufficient to cause JSN, highlighting the need for hip anatomy assessment on multiple planes. KEY POINTS: • Neither anterior nor lateral acetabular dysplasia was sufficient to independently reduce joint space width in a multivariate linear regression model of dysplastic hips. • A random forest classifier was developed based on measurements and demographic parameters from 507 hip joints, achieving an area under the curve of 69.9% in the external validation set, in predicting severe joint space narrowing based on anatomical hip parameters and age. • Unsupervised TwoStep cluster analysis revealed two distinct population groups, one with low and one with normal joint space width, characterised by differences in hip morphology.

MRI in the Diagnosis and Treatment Response Assessment of Chronic Nonbacterial Osteomyelitis in Children and Adolescents.

PURPOSE OF REVIEW: To explain the central role of magnetic resonance imaging (MRI) in the diagnosis and follow-up of chronic nonbacterial osteomyelitis (CNO) in children and adolescents, centering on practical technical aspects and salient diagnostic features. RECENT FINDINGS: In the absence of conclusive clinical features and widely accepted laboratory tests, including validated disease biomarkers, MRI (whether targeted or covering the entire body) currently plays an indispensable role in the diagnosis and therapy response assessment of CNO. Whole-body MRI, which is the reference imaging standard for CNO, can be limited to a short tau inversion recovery (STIR) coronal image set covering the entire body and a STIR sagittal set covering the spine, an approximately 30-min examination with no need for intravenous contrast or diffusion-weighted imaging. The hallmark of CNO is periphyseal (metaphyseal and/or epi-/apophyseal) osteitis, identified as bright foci on STIR, with or without inflammation of the adjacent periosteum and surrounding soft tissue. Response to bisphosphonate treatment for CNO has some unique MRI findings that should not be mistaken for residual or relapsing disease. Diagnostic features and treatment response characteristics of MRI in pediatric CNO are discussed, also describing the techniques used, pitfalls encountered, and differential diagnostic possibilities considered during daily practice.

Zero Echo Time Musculoskeletal MRI: Technique, Optimization, Applications, and Pitfalls.

Zero echo time (ZTE) imaging is an MRI technique that produces images similar to those obtained with radiography or CT. In ZTE MRI, the very short T2 signal from the mineralized trabecular bone matrix and especially cortical bone-both of which have a low proton density (PD)-is sampled in a unique sequence setup. Additionally, the PD weighting of the ZTE sequence results in less contrast between soft tissues. Therefore, along with gray-scale inversion from black to white and vice versa, ZTE imaging provides excellent contrast between cortical bone and soft tissues similar to that of radiography and CT. However, despite isotropic or near-isotropic three-dimensional (3D) imaging capabilities of the ZTE sequence, spatial resolution in this technique is still inferior to that of radiography and CT, and 3D volume renderings are currently time-consuming and require postprocessing software that features segmentation and manual contouring. Optimization of ZTE MRI mostly entails adjustments of bandwidth, flip angle, field of view, and image matrix. A wide range of structural abnormalities and disease or healing processes in the musculoskeletal system are well delineated with ZTE MRI, including conditions that involve bone-based morphometric analyses (which aid diagnosis, help prognostication, and guide surgery), impaction, avulsion and stress fractures, loose bodies or erosions in and around joints, soft-tissue calcifications and ossifications, and bone tumors (including treatment response). The pitfalls of ZTE imaging include mimics of foci of calcification or ossification such as intra-articular gas and susceptibility artifacts from surgical materials and hemosiderin deposition, which can be avoided in many instances by cross-referencing images obtained with other MRI sequences. Online supplemental material is available for this article. ©RSNA, 2022.

Spinal involvement in juvenile idiopathic arthritis: what do we miss without imaging?

Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic disease of childhood. Enthesitis-related arthritis (ERA) has been one of the most controversial subtypes of JIA with a higher risk of axial involvement.  Our aim was to assess the frequency and spectrum of MRI findings of spine involvement in patients with JIA and determine if the axial involvement is always clinically symptomatic in patients with positive MRI findings. In this retrospective cross-sectional observational study we included known or suspected JIA patients who underwent spinal MRI examination between 2015 and 2017 and followed up in the Pediatric Rheumatology outpatient clinic. The demographic and clinical data were reviewed from the medical charts and electronic records. All patients were grouped as clinically symptomatic and asymptomatic for spinal involvement and MRI findings were re-evaluated for presence of inflammatory and erosive lesions. Of the 72 JIA patients, 57 (79.2%) were diagnosed with ERA, and 15 (20.8%) with non-ERA subtypes of JIA. Overall, 49 (68%) patients with JIA had positive spinal MRI findings (inflammatory and/or erosive lesions). Twenty-seven (47%) ERA patients were clinically symptomatic for spine involvement and among them, 19 (70.3%) had positive spinal MRI findings. Although 30 ERA (53%) patients were clinically asymptomatic, 23 of them (77%) had positive spinal MRI findings, as well. Eleven (73%) patients diagnosed with non-ERA JIA subtypes were clinically symptomatic for spine involvement at the time of MRI. Among them, four (36.3%) had inflammatory and/or erosive lesions on spine MRI. Four (26%) non-ERA patients were clinically asymptomatic for spine involvement, but three (75%) of them showed positive findings on spinal MRI. Inflammatory and/or erosive lesions of the thoracolumbar spine could exist in patients with JIA, regardless of the presence of symptoms. Not only because the significant proportion of ERA patients show asymptomatic axial involvement but also the presence of axial involvement in patients who were classified as non-ERA depending on current ILAR classification underlines the necessity of using MRI for accurate classification of patients with JIA.

A Novel Physical Examination Test for Ischiofemoral Impingement: Validation With Magnetic Resonance Imaging Correlation.

OBJECTIVE: The purpose of this study was to propose and validate a novel physical examination test for ischiofemoral impingement with magnetic resonance imaging (MRI) correlation. METHODS: We prospectively studied 24 women with buttock (deep gluteal) pain and 27 asymptomatic women. Each group underwent a 2-stage physical examination test that featured hip adduction-external rotation-extension and knee flexion. Visual analog scale pain scores were noted just before and during test stages on both sides. The MRI findings of the ischiofemoral impingement were evaluated quantitatively and qualitatively. RESULTS: Mean ages were 56.0 and 55.2 years (P = 0.797), and mean body mass indexes were 29.1 and 28.8 kg/m2 (P = 0.817) in symptomatic and asymptomatic groups, respectively. Ischiofemoral spaces were significantly narrower (P < 0.001), ischial angles were wider (P < 0.001, right; P = 0.002, left), and soft tissue edema at the ischiofemoral space was more common (P < 0.001) in the symptomatic group, which also had higher pretest visual analog scale scores (P < 0.001) that increased significantly during both upright standing (P = 0.003, right; P < 0.001, left) and recumbent (P < 0.001 for both sides) stages of the physical examination test. CONCLUSIONS: A novel physical examination test significantly increases symptoms of ischiofemoral impingement with positive MRI correlation.

Diffusion-weighted imaging for the differentiation of Ewing sarcoma from osteosarcoma.

OBJECTIVE: The purpose of this study is to assess the ability of apparent diffusion coefficient (ADC) values in differentiating Ewing sarcoma and osteosarcoma. MATERIALS AND METHODS: This retrospective cross-sectional observational study included a total of 35 patients with a recent diagnosis of Ewing sarcoma (n = 13) and osteosarcoma (n = 22) who underwent conventional MRI and diffusion-weighted imaging (DWI). Three ADC measurements from the areas of the lowest diffusivity in ADC maps (ADCmin), and other areas with low diffusivity (ADCother), were made independently by two observers on pre-treatment MRI, and the means of these measurements were compared using independent samples t-test. Intraclass correlation coefficient was calculated for inter-observer agreement. RESULTS: There was a significant difference between the ADCmin (P < 0.001) and ADCother (P < 0.001) in Ewing sarcoma and osteosarcoma for both observers. For Ewing sarcoma and osteosarcoma, mean ADCmin was 0.566 ± 0.07 and 1.193 ± 0.33 × 10-3 mm2/s; 0.551 ± 0.08 and 1.182 ± 0.33 × 10-3 mm2/s; and mean ADCother was 0.813 ± 0.11 and 1.510 ± 0.35 × 10-3 mm2/s; 0811 ± 0.12 and 1.501 ± 0.33 × 10-3 mm2/s for observers 1 and 2, respectively. Inter-observer correlation coefficient for mean ADCmin was 0.994 and for mean ADCother was 0.995. CONCLUSION: Diffusion-weighted imaging and ADC values could be used in the differentiation of Ewing sarcoma and osteosarcoma in borderline cases.

Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma of bone: Clinicopathologic features of 5 cases.

Pseudomyogenic hemangioendothelioma (PHE) is an uncommon mesenchymal tumor of intermediate malignant potential with characteristic clinicopathologic and genetic features. Although bone involvement accompanies nearly one-fourth of reported cases of soft tissue PHEs, primary intraosseous PHE is rare. Herein, we report five cases of primary intraosseous PHEs. Male to female ratio was 4:1, with an average age of 28 years (age range, 5-44 years). Radiologically, tumors presented as lytic lesions in the proximal femur (two), diaphysis of the tibia (one), distal radius (one) and vertebrae (one). Multifocal lesions were observed in four cases. Histopathologic examination revealed plump spindle cells and prominent nucleoli. New bone formation was noted in three cases. Immunohistochemically, all tumors were positive for CD31 and negative for CD34. Pan Cytokeratin (CK) (AE1/3) was positively expressed in all, except a single tumor, in which CK7 and Cam5.2 were expressed. INI1/SMARCB1 was completely retained in all tumors. A single patient underwent surgical resection. During follow-up, two cases showed no evidence of disease within two and five years, respectively. Differential diagnosis of a PHE of bone includes osteoblastoma, epithelioid angiosarcoma, metastatic carcinoma, metastatic rhabdomyosarcoma, and epithelioid sarcoma. Caution must be exercised as pan CK (AE1/3) might not be expressed; therefore, the use of other cytokeratins, such as Cam5.2 is recommended. Awareness of such an entity in bone is the key to the diagnosis.

International Interdisciplinary Consensus Meeting on the Evaluation of Developmental Dysplasia of the Hip.

In September 2018, an international meeting of doctors of various disciplines, with expertise in the detection and treatment of DDH, was held in Csolyospalos, Hungary. The aim was to achieve consensus on the detection and early treatment of the condition and to develop a standardized system of teaching and training for hip ultrasound. There was strong agreement that US screening is essential. Specifically the Graf technique was selected as the technique of choice. Universal US screening was strongly favored. Screening should be carried out as soon as possible, but not later than the sixth week of age. US screening is cost-effective, does not result in overtreatment, and contributes to a reduction of long-term consequences. The essential principle of treatment is timely application of a device to achieve reduction, retention and maturation, by holding the hips in flexion, and a safe degree of abduction. It was agreed that the effectiveness of any screening policy depends on the correct scanning technique. Therefore, standardization of teaching and training of the Graf technique is mandatory. A unified teaching policy and materials should be developed for this purpose. Certification, re-certification and audit were discussed. The group, which has been formalized as the International Interdisciplinary Consensus Committee On DDH Evaluation (ICODE), will continue to meet and work towards establishing international consensus on DDH, standardizing and developing teaching and training of the Graf technique for hip US, and maintaining standards for detection and management.

Rotator cuff tear characteristics: how comparable are the pre-operative MRI findings with intra-operative measurements following debridement during arthroscopic repair?

PURPOSE: Magnetic resonance (MRI) is a valuable imaging method which can detect pre-operative rotator cuff tear characteristics accurately. However, tendon degeneration almost always necessitates a certain amount of debridement during arthroscopic repair, which alters tear size and shape. The aim of this study is to question the accuracy of the pre-operative tear size and classification in MRI and its relation to the tear size and type of the debrided tendon during arthroscopic repair. METHODS: A retrospective survey was performed to identify shoulders that underwent arthroscopic rotator cuff repair. Rotator cuff tears with an adequate history, a standard pre-operative MRI, and available surgical video records with appropriate measurements were included. Traumatic tears, calcifying tendonitis, isolated subscapularis tears, and revisions were excluded. In total, 60 shoulders' (30 males, 27 females; age 55.2 [35-73]) preoperative MRIs and intra-operative measurements were analyzed by orthopaedic surgeons and radiologists. Tear width and type were recorded. Interdisciplinary and intradisciplinary consistency of measurements and classifications were analyzed. Tear width measured on pre-operative MRI and after debridement were compared. RESULTS: Average measured tear width was 9 ± 5.3 mm on MRI. Surgeons (9.98 ± 4.6 mm) measured tears significantly wider than radiologists (7.71 ± 6.6 mm). Radiologists (ICC, 0.930; CI, 0.883-0.959) showed superior consistency on MRI than surgeons (CI, 0.502; CI, 0.105-0.726). Average tear width measured after debridement (29.3 ± 9.6 mm) was significantly higher than tear width measured on pre-operative MRI (p < 0.0001). None of the researchers assessing tear type on pre-operative MRI showed agreement with surgeons assessing intra-operative data. CONCLUSIONS: There were significant differences between the pre-operative tear characteristics on MRI and the debrided tendon characteristics during surgery, which were extensive enough to classify the tear in a different category.

Anterior inferior iliac spine morphology: quantitative and qualitative assessment in an asymptomatic population.

PURPOSE: To assess the prevalence of anterior inferior iliac spine (AIIS) types, and to investigate the quantitative measurements that characterize AIIS morphology in an asymptomatic adult population. METHODS: In this prospective study, 358 hips from 179 consecutive subjects (age range, 19-82 years; 91 males, 88 females), who underwent CT examination for reasons other than hip problems and were negative for hip impingement test, were analyzed. AIIS types were determined (1, flat wall of the ilium between distal end of AIIS and acetebular rim; 2, bony eminence between distal end of AIIS and acetebular rim; and 3, extension of AIIS to the anterior superior acetebular rim) and AIIS tip angle (TA), direct distance (DD) of the anterior acetabular rim to AIIS as well as projectional distances in vertical (VD) and horizontal (HD) planes were measured. Age- and gender-related factors were searched using two-way ANOVA test under three age groups (18-39, 40-59, and ≥ 60 years). RESULTS: There were 238 (66.5%) type 1, 118 (33.0%) type 2, and two (0.5%) type 3 AIISs, with significant difference between AIIS types among age groups and genders (P < 0.001). VD and DD showed age- and gender-related (P < 0.001, P < 0.001), and TA demonstrated gender-related differences (P < 0.001). Inter-observer agreement was good for TA and moderate to poor for other measurements. CONCLUSIONS: Type 1 AIIS is the most common shape across all age groups in adult females and in young and middle-aged adult males. TA, DD, and VD might be reliably used for the evaluation of AIIS morphology.

Recessive PIEZO2 stop mutation causes distal arthrogryposis with distal muscle weakness, scoliosis and proprioception defects.

The genetic work-up of arthrogryposis is challenging due to the diverse clinical and molecular etiologies. We report a-183/12-year-old boy, from a 2nd degree consanguineous family, who presented at 36/12 years with hypotonia, distal laxity, contractures, feeding difficulties at birth. He required surgery for progressive scoliosis at 16 years of age, and walked independently since then with an unstable gait and coordination defects. His latest examination at 18 years of age revealed a proprioceptive defect and loss-of-joint position sense in the upper limbs. Somatosensory evoked potentials supported bilateral involvement of dorsal column-medial lemniscal sensory pathways and nerve conduction studies revealed a mild axonal neuropathy. Muscle biopsy showed myopathic changes with neonatal myosin expression. Mendeliome sequencing led to the discovery of a recessive stop mutation in piezo-type mechanosensitive ion channel component 2 (PIEZO2, NM_022068, c.1384C>T, p.R462*). PIEZO2 is a nonselective cation channel, expressed in sensory endings of proprioceptors innervating muscle spindles and Golgi tendon organs. Dominant PIEZO2 mutations were described in patients with distal arthrogryposis type 5 and Marden-Walker syndrome. Sensory ataxia and proprioception defect with dorsal column involvement together with arthrogryposis, myopathy, scoliosis and progressive respiratory failure may represent a distinct clinical phenotype, and indicate recessive mutations in PIEZO2.

Magnetic Resonance Imaging (MRI) of Snapping Scapula in a 10-Year-Old Boy.

BACKGROUND: Snapping scapula syndrome, also known as scapulothoracic crepitus or bursitis, is a manifestation of a mechanical abnormality of the scapulothoracic joint. In addition to characteristic findings on physical examination, magnetic resonance imaging (MRI) exquisitely reveals soft tissue changes such as muscle edema and scapulothoracic bursitis. CASE REPORT: We present a case of a 10-year-old boy who had snapping scapula syndrome of the right scapula that was associated with edema of the serratus anterior muscle at the scapulothoracic interface and with scapulothoracic, specifically supraserratus, bursitis on MRI. CONCLUSIONS: MRI in snapping scapula syndrome, which is a clinical diagnosis, exquisitely reveals soft tissue changes such as muscle edema and scapulothoracic bursitis. Such soft tissue findings of snapping scapula syndrome need to be kept in mind while evaluating routine shoulder and/or scapular region MRI, especially in the absence of relevant clinical information at the time of the imaging study.

Accessory Anterolateral Talar Facet in Populations With and Without Symptoms: Prevalence and Relevant Associated Ankle MRI Findings.

OBJECTIVE: The purpose of this study was to determine the prevalence of and relevant findings associated with the accessory anterolateral talar facet, which may have a role in talocalcaneal impingement and sinus tarsi syndrome, on ankle MR images of persons with and those without symptoms. SUBJECTS AND METHODS: In this case-control study, three observers independently reviewed 1.5-T or 3-T MR images of 110 ankles with symptoms in 100 consecutively registered patients (age range, 16-79 years; mean, 41.5 years) and limited 1.5-T MR images of 104 age-, sex-, and side-matched ankles in 104 volunteers without symptoms for the presence of an accessory anterolateral talar facet, calcaneal cortical thickness, subjacent talar or calcaneal cystic and bone marrow edema-like changes at the angle of Gissane, and sinus tarsi fat obliteration. RESULTS: An accessory anterolateral talar facet was present in 36 (32.7%) ankles with symptoms versus 27 (26.0%) symptom-free ankles (p = 0.297). Interobserver agreement was almost perfect (κ = 0.851; 95% CI, 0.772-0.929) for the detection of accessory anterolateral talar facet and substantial for the detection of sinus tarsi fat obliteration (κ = 0.671; 95% CI, 0.427-0.915). The angle of Gissane was significantly smaller in persons with an accessory anterolateral talar facet, either with or without symptoms (p < 0.0001). Subjacent talar (p = 0.003) and calcaneal (p = 0.033) bone marrow edema-like change and sinus tarsi fat obliteration (p = 0.034) were significantly more frequent in persons with accessory anterolateral talar facet, but chronic reactive osseous changes at the angle of Gissane were not (p > 0.05). CONCLUSION: The higher prevalence of the MRI finding of an accessory anterolateral talar facet in ankles with symptoms is not statistically significant. This facet may be associated with subjacent talar bone marrow edema-like change on MR images of individuals with and those without symptoms and with sinus tarsi fat obliteration in individuals with symptoms.

Association of Medial Meniscus Extrusion With the Prominence of a Fascicular Capsulofemoral Band Subjacent to the Deep Medial Collateral Ligament.

OBJECTIVE: The objective of our study was to test our hypothesis that a transverse oblique fascicular anteromedial capsulofemoral band partially subjacent to the deep medial collateral ligament (MCL) is more prominent in knees with medial meniscal extrusion. MATERIALS AND METHODS: We retrospectively analyzed all knee MRI examinations from a 6-month period for the presence and dimensions of the anteromedial capsulofemoral band on coronal proton-density fat-saturated images and also for medial meniscus extrusion, which was defined as extrusion of 3 mm or greater. Edemalike signal intensity within or in the vicinity of the anteromedial capsulofemoral band, partial or complete tears of the MCL, a history of MCL surgery, or a neoplastic mass lesion violating the medial supporting structures were exclusion criteria. We reviewed procedural videos of patients who subsequently underwent knee arthroscopy. MRI of a cadaveric knee was performed and was followed by dissection and histologic examination. RESULTS: MRI examinations of 346 knees of 312 patients met the inclusion criteria; of these knees, 50 had medial meniscus extrusion. The anteromedial capsulofemoral band was discernible on MRI in all knees except five (98.6%), and it was visible in six of the arthroscopy videos of 17 knees. The anteromedial capsulofemoral band was thicker on MRI of patients with medial meniscus extrusion (p < 0.0001). The anteromedial capsulofemoral band was identified on MRI and at dissection of the cadaveric knee, and histologic examination revealed that the anteromedial capsulofemoral band was a capsuloligamentous structure. CONCLUSION: A transverse oblique anteromedial capsulofemoral band subjacent to the deep MCL is thicker in knees with medial meniscus extrusion.

Ischiofemoral Space on MRI in an Asymptomatic Population: Normative Width Measurements and Soft Tissue Signal Variations.

OBJECTIVES: To make normative width measurements of the ischiofemoral (IF) space in an asymptomatic population and to record soft tissue MRI signal variations within the IF space in order to determine whether such variations are associated with IF space dimensions. METHODS: Normative width measurements of the IF space were prospectively made in 418 hips on 1.5 T MR images of 209 asymptomatic volunteers. Quantitative and qualitative assessments of the IF soft tissues including the quadratus femoris (QF) muscle were also made. RESULTS: The mean IF space width was 2.56 ± 0.75 cm (right, 2.60 ± 0.75 cm; left, 2.53 ± 0.75 cm). Soft tissue MRI signal abnormalities were present within the IF space in 19 (9.1 %) of 209 volunteers. Soft tissue abnormalities within the IF space included oedema (3/209, 1.4 %) of the QF and/or surrounding soft tissue, and only fatty infiltration (16/209, 7.7 %) of the QF. CONCLUSIONS: Bilateral IF spaces are asymmetrical in asymptomatic persons. There is ≥10 % of width difference between right and left IF spaces in approximately half of asymptomatic individuals. Fatty infiltration and oedema can be present at the IF space in a small portion of the asymptomatic population, who also have narrower IF spaces than those without soft tissue MRI signal abnormalities. KEY POINTS: • Bilateral IF spaces are commonly asymmetrical in asymptomatic individuals. • MRI signal abnormalities can be observed within IF space in asymptomatic people. • Abnormal quantitative/qualitative MRI findings are not necessarily related to IF impingement.