Posterolateral dislocation and incarceration of the long head of the biceps tendon: a rare cause of irreducible anterior glenohumeral joint dislocation-a case report and brief review of the literature.

Failure of closed reduction of anterior glenohumeral joint dislocation is infrequent. It can be secondary to osseous (e.g., fracture fragments or Hill-Sachs lesion) or soft tissue (e.g., labrum or rotator cuff tendon) impediments. Herein, we present a case of a prolonged irreducible glenohumeral joint secondary to a posterolaterally dislocated and incarcerated long head of the biceps tendon after an episode of anterior instability, highlight the utility of MR imaging for guiding management, and review the literature of this sporadic diagnosis.

Effect of different ankle joint positions on medial gastrocnemius muscle fiber strains during isometric plantarflexion.

Muscle force production is influenced by muscle fiber and aponeurosis architecture. This prospective cohort study utilizes special MR imaging sequences to examine the structure-function in-vivo in the Medial Gastrocnemius (MG) at three-ankle angles (dorsiflexion, plantar flexion-low and high) and two sub-maximal levels of maximum voluntary contraction (25% and 50%MVC). The study was performed on 6 young male participants. Muscle fiber and aponeurosis strain, fiber strain normalized to force, fiber length and pennation angle (at rest and peak contraction) were analyzed for statistical differences between ankle positions and %MVC. A two-way repeated measures ANOVA and post hoc Bonferroni-adjusted tests were conducted for normal data. A related samples test with Friedman's 2-way ANOVA by ranks with corrections for multiple comparisons was conducted for non-normal data. The dorsiflexed ankle position generated significantly higher force with lower fiber strain than the plantarflexed positions. Sarcomere length extracted from muscle fiber length at each ankle angle was used to track the location on the Force-Length curve and showed the MG operates on the curve's ascending limb. Muscle force changes predicted from the F-L curve going from dorsi- to plantarflexion was less than that experimentally observed suggesting other determinants of force changes with ankle position.

Intramuscular Degloving Injury of the Rectus Femoris From Kickball: A Case Report and Review.

Intramuscular degloving injuries (IDIs) are a rare and unique type of muscle injury where there is a dissociation between the inner and outer components of a particular muscle. This type of injury is seen exclusively within the rectus femoris (RF) muscle due to its unique muscle-within-a-muscle anatomy and represents 9% of RF injuries. Despite the significance of this injury, limited knowledge exists regarding the mechanism, management, and prognosis of IDIs, and IDIs are not currently included among the various muscle injury classifications. We present a 38-year-old active male with a one-week history of acute onset right anterior mid-thigh pain and palpable lump after playing kickball. Right thigh MRI revealed an IDI of the RF muscle, edema within the inner and outer muscular portions of the muscle, and a retraction of the torn inner indirect myotendinous complex of the RF. He was managed with physical therapy while being advised to avoid aggressive quadriceps contractions, high-intensity, or high-impact exercise. This is the first reported case of an IDI that occurred in an older recreational athlete (versus young competitive athletes), and the first case of an IDI in a kicking sport other than soccer (kickball). This case emphasizes the importance of a broader awareness of this injury, and a heightened index of suspicion is advised in assessing potential IDIs to improve patient prognosis and rehabilitation. Given the limited understanding and rarity of this injury, we also provide a comprehensive review describing the IDI to the RF.

Time-dependent diffusion tensor imaging and diffusion modeling of age-related differences in the medial gastrocnemius and feasibility study of correlations to histopathology.

PURPOSE: Implement STEAM-DTI to model time-dependent diffusion eigenvalues using the random permeable barrier model (RPBM) to study age-related differences in the medial gastrocnemius (MG) muscle. Validate diffusion model-extracted fiber diameter for histological assessment. METHODS: Diffusion imaging at different diffusion times (Δ) was performed on seven young and six senior participants. Time-dependent diffusion eigenvalues (λ2 (t), λ3 (t), and D⊥ (t); average of λ2 (t) and λ3 (t)) were fit to the RPBM to extract tissue microstructure parameters. Biopsy of the MG tissue for histological assessment was performed on a subset of participants (four young, six senior). RESULTS: λ3 (t) was significantly higher in the senior cohort for the range of diffusion times. RPBM fits to λ2 (t) yielded fiber diameters in agreement to those from histology for both cohorts. The senior cohort had lower values of volume fraction of membranes, ζ, in fits to λ2 (t), λ3 (t), and D⊥ (t) (significant for fit to λ3 (t)). Fits of fiber diameter from RPBM to that from histology had the highest correlation for the fit to λ2 (t). CONCLUSION: The age-related patterns in λ2 (t) and λ3 (t) could tentatively be explained from RPBM fits; these patterns may potentially arise from a decrease in fiber asymmetry and an increase in permeability with age.

Strain and Strain Rate Tensor Mapping of Medial Gastrocnemius at Submaximal Isometric Contraction and Three Ankle Angles.

INTRODUCTION: The aim of this study is to analyze the muscle kinematics of the medial gastrocnemius (MG) during submaximal isometric contractions and to explore the relationship between deformation and force generated at plantarflexed (PF), neutral (N) and dorsiflexed (DF) ankle angles. METHOD: Strain and Strain Rate (SR) tensors were calculated from velocity-encoded magnetic resonance phase-contrast images in six young men acquired during 25% and 50% Maximum Voluntary Contraction (MVC). Strain and SR indices as well as force normalized values were statistically analyzed using two-way repeated measures ANOVA for differences with force level and ankle angle. An exploratory analysis of differences between absolute values of longitudinal compressive strain (Eλ1) and radial expansion strains (Eλ2) and maximum shear strain (Emax) based on paired t-test was also performed for each ankle angle. RESULTS: Compressive strains/SRs were significantly lower at 25%MVC. Normalized strains/SR were significantly different between %MVC and ankle angles with lowest values for DF. Absolute values of Eλ2 and Emax were significantly higher than Eλ1 for DF suggesting higher deformation asymmetry and higher shear strain, respectively. CONCLUSIONS: In addition to the known optimum muscle fiber length, the study identified two potential new causes of increased force generation at dorsiflexion ankle angle, higher fiber cross-section deformation asymmetry and higher shear strains.

Imaging Among the Underserved: Utilization and Expenditures in a Student-Run Free Clinic.

OBJECTIVE: To determine imaging utilization and expenditures among an underserved population at a student-run free clinic. METHODS: This was a retrospective review of billing records for all radiology studies performed over a 4-year period at a student-run free clinic supervised by physician faculty. All imaging services were outsourced through either direct payment by the clinic to a local imaging group or through in-kind donations. Radiology studies were grouped by modality and diagnostic category. Data were analyzed to determine overall and average imaging utilization and expenditures. RESULTS: Across the 4-year study period, 413 radiology studies were performed with a yearly average of 103 (SD = 16). During this time, 192 (46%) ultrasounds, 123 (30%) radiographic studies, 40 (10%) MRIs, 37 (9%) CTs, 8 (2%) interventional procedures, and 5 (1%) nuclear imaging studies were obtained. Overall, expenditures were $157,888 with a yearly average of $39,472 (SD = $1982). In-kind donations accounted for $138,508 (88%) of expenditures. Across the 4-year study period, utilization increased by 15% with less than 1% increase in expenditures. DISCUSSION: Ultrasound was the most common imaging modality used. Overall imaging utilization was considerably less than that of published data in an ambulatory setting.

MRI Based Fiber Strain Mapping of the Medial Gastrocnemius Muscle at Submaximal Isometric Contractions at Different Ankle Angles.

Muscle force production is influenced by muscle fiber and aponeurosis architecture. This prospective cohort study utilizes special MR imaging sequences to examine the structure-function in-vivo in the Medial Gastrocnemius (MG) at three-ankle angles (dorsiflexion, neutral, and plantar flexion) and two sub-maximal levels of maximum voluntary contraction (25% and 50% MVC). The study was performed on 6 young male subjects. Muscle fiber and aponeurosis strain, fiber strain normalized to force, fiber length and pennation angle (at rest and peak contraction) were analyzed for statistical differences between ankle positions and %MVC. A two-way repeated measures ANOVA and post hoc Bonferroni-adjusted tests were conducted for normal data. A related samples test with Friedman's 2-way ANOVA by ranks with corrections for multiple comparisons was conducted for non-normal data. The dorsiflexed ankle position generated significantly higher force with lower fiber strain than neutral and plantarflexed positions. Sarcomere length extracted from muscle fiber length at each ankle angle was used to track the location on the Force-Length curve and showed the MG operates on the curve's ascending limb. Muscle force changes predicted from the F-L curve going from dorsi- to plantarflexion was less than that experimentally observed suggesting other determinants of force changes with ankle position.

Hindfoot Fractures: Injury Patterns and Relevant Imaging Findings.

The hindfoot consists of the talus and calcaneus, spans the tibiotalar to transverse tarsal joints, and is critical for support of body weight and absorption and transfer of physiologic loads during bipedal movements. Hindfoot fractures account for approximately 17% of foot and ankle fractures, with calcaneal fractures being more common than talar fractures. Hindfoot fractures are usually caused by high-impact axial loads such as falls from heights and motor vehicle accidents, and understandably, they are often seen in patients with polytrauma. Long term, these fractures have implications in development of posttraumatic osteoarthrosis with associated pain and stiffness, affecting daily living activities. An overview of the talus and calcaneus is presented, with emphasis on fractures with articular involvement-namely, the tibiotalar and subtalar joints. Articular talar and calcaneal injuries can also alter hindfoot alignment, causing ankle and foot function abnormalities. Optimal treatment-that is, restoration of articular surfaces and hindfoot alignment followed by rigid fixation until fracture union-is dependent on an accurate understanding of the injury that is well depicted with imaging, radiography and CT in particular. The discussion of talar and calcaneal fractures includes a review of the normal anatomy, epidemiologic factors, classification systems, and imaging and pathologic-anatomic features of common injury patterns. This review is intended to aid surgical management and restoration of articular and hindfoot alignment for optimal ankle and foot function, thereby reducing patient morbidity in these often devastating injuries. ©RSNA, 2022.

Osteochondritis dissecans of the talar dome in patients with tarsal coalition.

OBJECTIVE: Tarsal coalition is known to cause abnormal talocrural stress, hindfoot malalignment, and ankle sprains. These can all be associated with osteochondritis dissecans (OCD) of the talar dome. We present the first detailed description of a series of talar OCDs occurring in patients with tarsal coalition, with the goal of determining whether there is an increased prevalence of OCDs among patients with tarsal coalition. MATERIALS AND METHODS: We studied ankle MRIs in 57 patients with tarsal coalitions, excluding those with a reported inciting traumatic event. The MRIs were performed on magnetic field strengths ranging from 0.3 to 1.5 T and included axial, coronal, and sagittal T1 and T2 or PD fat-suppressed sequences. We evaluated the morphology and location of classically described OCDs in these patients, type and location of concomitant tarsal coalition, and, when available, the presence of pes planus and hindfoot valgus on weight-bearing radiographs. Chi-squared analysis was used to compare categorical variables and a Student's t test was used for parametric continuous variables. Additionally, logistic regression was used to compute the odds ratio of talar OCD associated with patient age, gender, laterality, pes planus status, hindfoot valgus status, and coalition type. RESULTS: Eighty-nine percent of tarsal coalitions were non-osseous coalitions and the calcaneonavicular space was the most common site of abnormal tarsal connection (54.4%). In the 29 patients with tarsal coalitions and talar OCDs, OCDs commonly occurred medially (75.9%). In the sagittal plane, talar OCDs occurred centrally, with only one case sparing the central talar dome. The mean surface area of the 29 OCDs was 89.7 mm2. Both osseous coalition and hindfoot valgus were associated with smaller talar OCD mean surface area (p = 0.015 and p = 0.0001, respectively). There was no association between depth and surface area of talar OCD with either coalition location or presence of pes planus (coalition location: p = 0.455 for depth and p = 0.295 for surface area; presence of pes planus: p = 0.593 for depth and p = 0.367 for surface area). CONCLUSION: Talar OCD prevalence is higher in patients with tarsal coalition than that reported for the general population. This occurrence may relate to altered biomechanics and repetitive talocrural stress owing to altered subtalar motion, particularly given the findings of increased odds of talar OCD in older patients, as well as weak associations between OCD surface area and both non-osseous coalition and hindfoot alignment. However, we did not find any specific OCD morphologic features attributable to the precise location of the tarsal coalition.

Starting a Free Ultrasound Clinic for the Underserved: Considerations and Overcoming Challenges.

Many radiologists are interested in providing affordable care to underserved populations but are unsure how to accomplish it. We present a model for providing imaging services to the underserved with an emphasis on the challenges we encountered and strategies we used to overcome them. In partnership with our medical school's student-run free clinic, we developed a community-based ultrasound service that provides diagnostic ultrasound examinations to an uninsured urban population to address the need of timely access to care and integrated follow-up care. Image storage and reporting were fully integrated with our existing imaging informatics and electronic medical record systems. Radiology residents play a central role in the operation of the service while gaining hands-on ultrasound experience, in partnership with volunteer sonographers, radiology attendings, and medical students.

Posttraumatic subarachnoid fat embolism: Case presentation and literature review.

Fat embolism in the subarachnoid space has a unique pathophysiology and clinical picture when compared to fat embolism syndrome. Lipid deposits in the subarachnoid space-most commonly the sequela of dermoid rupture in the neuraxis-can cause an inflammatory reaction leading to irritation of nearby neurovascular structures. Herein, we report the only case in the United States, to our knowledge, of a patient diagnosed with subarachnoid fat emboli secondary to sacral fracture who initially presented with a normal head CT and subsequently developed visual changes.

Manubrial pseudolesion: a secondary sign of thoracic outlet syndrome.

Marrow enhancement mimicking sclerotic osseous disease, or the so-called transient "pseudolesion," has frequently been described in vertebral bodies supplied by collateral basivertebral venous flow in the setting of central venous obstruction. Pseudolesions involving the sternum are much rarer and have only been described in the setting of malignant central venous obstruction. We report a case of an incidental manubrial pseudolesion on contrast-enhanced CT prompting further investigation for thoracic outlet syndrome.

Osteochondroma of the temporal styloid process: a common disease in a rare but vulnerable location.

Osteochondromas, the most common benign bone tumor, are typically asymptomatic and discovered incidentally by imaging. Most frequently, osteochondromas occur at the metaphyses of long bones, and rarely involve the head and neck. We report the first case of a symptomatic osteochondroma of the temporal styloid process causing facial nerve paralysis.

Mallet hallux injury: A case report and literature review.

Mallet injury is associated with variable degrees of extensor hallucis longus tendon tearing, ultimately leading to the well-known mallet toe deformity; this entity, commonly described at the lesser toes and fingers, has rarely been reported at the hallux. We present a surgically proven case of mallet hallux injury with radiographic and magnetic resonance imaging assessment and review the literature, including clinical and radiological findings, along with basic treatment concepts.

Calcium hydroxyapatite deposition disease: Imaging features and presentations mimicking other pathologies.

OBJECTIVE: Calcium hydroxyapatite depositional disease (HADD) is usually asymptomatic and self-limiting; however, when there is an associated inflammatory process or HADD occurs in an unusual location, it may mimic trauma, infection, or neoplasm. The purpose of this article is to review the imaging features of HADD and how to distinguish it from more worrisome entities that can have similar appearances. CONCLUSION: An understanding of the presentations of HADD is important to allow early and confident diagnosis. In particular, familiarity with presentations that resemble more ominous pathologies is essential to avoid costly and time-consuming workup or intervention.