From the RSNA Refresher Courses. Radiological Society of North America. MR imaging of the ankle and foot

[Normal Development and Variants in Pediatric Bone]

Normal variants refer to imaging findings that are generally asymptomatic and discovered incidentally, yet may exhibit findings similar to those observed in pathological conditions. Recognizing normal variants in pediatric bone requires comprehension of the developmental process of long tubular bones and secondary ossification centers. Familiarity with various radiological findings of normal variants can prevent unnecessary follow-up imaging tests, as well as incorrect diagnosis and treatment. In this review, we will discuss the characteristic imaging findings of normal variants seen in growing pediatric bones, along with strategies for distinguishing them from pathologic conditions.

Patterns of ankle injury in soccer: MRI clues to traumatic mechanism

Understanding the traumatic mechanisms of ankle injuries in soccer is crucial for an accurate and complete MRI diagnosis. Many ankle injuries share universal mechanisms seen in other athletic activities, but certain patterns are found to be more specific and relatively unique to soccer. Ankle impingement syndromes encountered in soccer encompass a spectrum of disorders that include anterior and posterior impingement categories, with anterior impingement representing pathology relatively specific to soccer. Lateral ligamentous sprains are one of the most common injuries; however, there is a higher rate of injuries to the medial structures in soccer as compared to other sports. Ankle fractures are uncommon in soccer while bone contusions and chondral and osteochondral injuries frequently accompany ligamentous sprains. Tendon abnormalities in soccer most commonly result from overuse injuries and typically affect peroneal tendons, posterior and anterior tibialis tendons, and Achilles tendon. Acute Achilles tendon ruptures occur in both recreational players and elite soccer athletes. Tibialis anterior friction syndrome may mimic tibial stress fractures. Long-term sequelae of acute traumatic and chronic overuse ankle injuries in professional soccer players manifest as ankle osteoarthritis that is more prevalent compared to not only the general population, but also to former elite athletes from other sports. This article examines the most common and specific injuries in soccer in order of their frequency.

Don't Miss Me: Midfoot Sprains, A Point-of-Care Review

Athletes practicing high-contact sports are exposed to an increased risk of midfoot injuries, namely midtarsal sprains. The complexity of reaching an accurate diagnosis is clearly depicted in the reported incidence of midtarsal sprains, ranging from 5% to 33% of ankle inversion injuries. Because the focus of the treating physician and physical therapist is on lateral stabilizing structures, midtarsal sprains are missed at initial evaluation in up to 41% of patients, with delayed treatment as a result.Detecting acute midtarsal sprains requires a high degree of clinical awareness. Radiologists must become familiar with the characteristic imaging findings of normal and pathologic midfoot anatomy to avoid adverse outcomes such as pain and instability. In this article we describe Chopart joint anatomy, mechanisms of midtarsal sprains, clinical importance, and key imaging findings with a focus on magnetic resonance imaging. A team effort is essential to provide optimal care for the injured athlete.

MRI in Acute Ankle Sprains: Should We Be More Aggressive with Indications?

Acute ankle sprains are common sports injuries. MRI is the most accurate test for assessing the integrity and severity of ligament injuries in acute ankle sprains. However, MRI may not detect syndesmotic and hindfoot instability, and many ankle sprains are treated conservatively, questioning the value of MRI. In our practice, MRI adds value in confirming the absence or presence of ankle sprain-associated hindfoot and midfoot injuries, especially when clinical examinations are challenging, radiographs are inconclusive, and subtle instability is suspected. This article reviews and illustrates the MRI appearances of the spectrum of ankle sprains and associated hindfoot and midfoot injuries.

Imaging of Acute Ankle and Foot Sprains

Ankle and foot injuries are very common injuries in the general population, and more so in athletes. MR imaging is the optimal modality to evaluate for ligamentous injuries of the ankle and associated conditions after ankle sprain. In this article, the authors discuss the epidemiology, biomechanics, normal anatomy, and pathology of the ankle as well as injuries of the hindfoot and midfoot that are often associated with ankle injuries.

Deep learning-based acceleration of Compressed Sense MR imaging of the ankle

OBJECTIVES

To evaluate a compressed sensing artificial intelligence framework (CSAI) to accelerate MRI acquisition of the ankle.

METHODS

Thirty patients were scanned at 3T. Axial T2-w, coronal T1-w, and coronal/sagittal intermediate-w scans with fat saturation were acquired using compressed sensing only (12:44 min, CS), CSAI with an acceleration factor of 4.6-5.3 (6:45 min, CSAI2x), and CSAI with an acceleration factor of 6.9-7.7 (4:46 min, CSAI3x). Moreover, a high-resolution axial T2-w scan was obtained using CSAI with a similar scan duration compared to CS. Depiction and presence of abnormalities were graded. Signal-to-noise and contrast-to-noise were calculated. Wilcoxon signed-rank test and Cohen's kappa were used to compare CSAI with CS sequences.

RESULTS

The correlation was perfect between CS and CSAI2x (κ = 1.0) and excellent for CS and CSAI3x (κ = 0.86-1.0). No significant differences were found for the depiction of structures between CS and CSAI2x and the same abnormalities were detected in both protocols. For CSAI3x the depiction was graded lower (p ≤ 0.001), though most abnormalities were also detected. For CSAI2x contrast-to-noise fluid/muscle was higher compared to CS (p ≤ 0.05), while no differences were found for other tissues. Signal-to-noise and contrast-to-noise were higher for CSAI3x compared to CS (p ≤ 0.05). The high - resolution axial T2-w sequence specifically improved the depiction of tendons and the tibial nerve (p ≤ 0.005).

CONCLUSIONS

Acquisition times can be reduced by 47% using CSAI compared to CS without decreasing diagnostic image quality. Reducing acquisition times by 63% is feasible but should be reserved for specific patients. The depiction of specific structures is improved using a high-resolution axial T2-w CSAI scan.

KEY POINTS

• Prospective study showed that CSAI enables reduction in acquisition times by 47% without decreasing diagnostic image quality. • Reducing acquisition times by 63% still produces images with an acceptable diagnostic accuracy but should be reserved for specific patients. • CSAI may be implemented to scan at a higher resolution compared to standard CS images without increasing acquisition times.

The Role of Diffusion Weighted MR Imaging in the Diagnosis of Tendon Injuries of the Ankle and Foot

Background and objectives: Our aim is to determine the diagnostic performance and utility of Diffusion Weighted MR Imaging (DWI) against the routine Magnetic Resonance Imaging (MRI) for the evaluation of patients with tendon injuries of the ankle and foot. Materials and Method: After institutional review board approval and informed consent taken from all the patients, ankle and foot MR imaging and DWI-Apparent Diffusion Coefficient (ADC) mapping were performed on the 81 injured tendons of 50 patients. All tendon injuries were named as Rupture (R), Partial tear (PT), and Tenosynovitis (T). Diagnostic interpretation was based on the MRI-DWI and ADC mapping, verified by either open surgery, diagnostic arthroscopy, or conservative procedures-splint application. Statistical analysis of this research was assessed by Fischer’s exact test, variance analysis test between dependent groups, Receiver Operating Characteristics (ROC) curve, and Pearson chi square statistics. Results: MRI depicted all tendon injuries with 70% sensitivity and 100% specificity, and showed a significant statistical relationship to surgical and arthroscopic references with high agreement (p < 0.05, k: 0.609). DWI had 100% sensitivity and 83–90% specificity for the visualization of tendon injuries with certain agreement and a significant statistical relationship to the gold standard (p < 0.05, k: 0.890–0.899). For all those injured tendons, DWI had 100% sensitivity for the diagnosis of R, and 92–97% sensitivity corresponding to PT and T over routine ankle MR imaging. The specificity of DWI to MRI ranged from 75 to 44% for all the injured tendons. DWI had significant statistical superiority over MRI for the visualization of R, PT, and T of all tendons included in this research (p < 0.05). Conclusions: DWI is a good imaging modality for the visualization of ankles with tendon injuries, possibly further improving the sensitivity of the classical ankle and foot MRI, and supplying more beneficial and diagnostic information than routine MR imaging on the basis of R, PT, and T of tendons at the ankle and foot.

Bone marrow edema of the medioplantar talar head is associated with severe ligamentous injury in ankle sprain

PURPOSE

To investigate the predictive value of talar head edema (THE) in acute ankle sprain for the presence of concomitant ligament injuries.

METHODS

This retrospective study was approved by the ethics committee and informed consent was obtained. One hundred patients (mean age: 37 years ± 14 [standard deviation], range 13-77 years) with MRI of the ankle after acute trauma were included. The cohort in this matched-pair study consisted of 50 patients with THE (group 1) and 50 patients without THE (group 2). Two readers independently evaluated presence and size of bone marrow edema of the talus head and injuries of the lateral, medial, talonavicular, and spring ligament complex. Statistics included intraclass correlation coefficient (ICC) and Kappa statistics as well as parametric and non-parametric tests.

RESULTS

On average, patients with THE demonstrated significantly more ligament injuries in comparison to patients without THE (3.7 vs. 1.3, p ≤ 0.01). Also, in patients with THE, the number of injured ligaments was significantly higher at the lateral (p = 0.03), medial (p ≤ 0.01), and talonavicular (p ≤ 0.01) compartment in comparison to patients without THE. The most frequently injured ligaments in patients with THE were the anterior talofibular ligament (60%) and the anterior tibiotalar ligament (42%). There was no significant correlation between edema size and the number of injured ligaments or compartments (p = 0.5).

CONCLUSION

THE is associated with more extensive ligamentous ankle injury, in particular to the medial and lateral collateral ligament complex, and therefore indicative of severe ankle trauma.

Accuracy of MRI-Based Talar Cartilage Thickness Measurement and Talus Bone and Cartilage Modeling: Comparison with Ground-Truth Laser Scan Measurements

OBJECTIVE

The purpose of this work was to compare measurements of talar cartilage thickness and cartilage and bone surface geometry from clinically feasible magnetic resonance imaging (MRI) against high-accuracy laser scan models. Measurement of talar bone and cartilage geometry from MRI would provide useful information for evaluating cartilage changes, selecting osteochondral graft sources or creating patient-specific joint models.

DESIGN

Three-dimensional (3D) bone and cartilage models of 7 cadaver tali were created using (1) manual segmentation of high-resolution volumetric sequence 3T MR images and (2) laser scans. Talar cartilage thickness was compared between the laser scan- and MRI-based models for the dorsal, medial, and lateral surfaces. The laser scan- and MRI-based cartilage and bone surface models were compared using model-to-model distance.

RESULTS

Average cartilage thickness within the dorsal, medial, and lateral surfaces were 0.89 to 1.05 mm measured with laser scanning, and 1.10 to 1.22 mm measured with MRI. MRI-based thickness was 0.16 to 0.32 mm higher on average in each region. The average absolute surface-to-surface differences between laser scan- and MRI-based bone and cartilage models ranged from 0.16 to 0.22 mm for bone (MRI bone models smaller than laser scan models) and 0.35 to 0.38 mm for cartilage (MRI bone models larger than laser scan models).

CONCLUSIONS

This study demonstrated that cartilage and bone 3D modeling and measurement of average cartilage thickness on the dorsal, medial, and lateral talar surfaces using MRI were feasible and provided similar model geometry and thickness values to ground-truth laser scan-based measurements.

3-T MRI of the Ankle Tendons and Ligaments

Ankle sprain is the most common injury in athletic populations. Ligament and tendon pathologies of the ankle are common, ranging from traumatic injuries to degeneration leading to chronic pain and acquired foot deformities. MRI is the imaging modality of choice to evaluate tendon and ligament pathology of the ankle, specifically derangements of tendons and ligaments. 3-T MRI offers improved imaging characteristics relative to 1.5-T MRI, allowing for better delineation of anatomic detail and pathology. This article provides a review of the anatomy and common pathologies of the ankle ligaments and tendons using high-resolution 3-T MRI.

The Added Diagnostic Value of the Bright Rim Sign to Conventional MRI Assessment of Anterior Talofibular Ligament Disruption

RATIONALE AND OBJECTIVES

The bright rim sign (BRS) was used as a reliable indicator of anterior talofibular ligament (ATFL) disruption beside other well-known diagnostic criteria. Although this sign can improve accuracy of conventional magnetic resonance imaging (MRI) in diagnosis of ATFL disruption, it was not adequately discussed in the literature. This study aimed to confirm the added diagnostic value of BRS to conventional MRI assessment of ATFL disruption.

MATERIALS AND METHODS

A prospective study included 62 patients (47 males and 15 females; mean age, 36.9 ± 12.1 years; range, 17-52 years) with clinically suspected ATFL disruption. All patients underwent MRI and arthroscopy of ankle. MRI images were evaluated for the presence of ligament disruption sign (LDS) and BRS. The patients were classified into 3 groups: group 1 included patients with acute lateral ankle ligament sprain; group 2 included patients with chronic ankle instability; and group 3 included patients with recurring ankle sprain. The diagnostic value of the BRS was evaluated using arthroscopy as reference standard.

RESULTS

The diagnostic value of both signs together increased overall sensitivity in detecting ATFL disruption to 86.7% compared to 60% when considering LDS alone (p < 0.0001). In group 1 and 3, the sensitivity increased when both signs were considered together compared to LDS alone (p = 0.004 and 0.025, respectively). In group 2, there was a trend toward significance in sensitivity when both signs were considered compared to LDS alone (p = 0.08).

CONCLUSION

BRS is a very helpful diagnostic sign in assessment of ATFL disruption when considered conjointly with the LDS.

A Rare Pattern of Ligamentous Injury of the Ankle: A Case Report and Review of the Literature

Ankle sprains are the most frequent sport related injuries with involvement of the lateral collateral ligament complex occurring in 85% of cases. Isolated anterior talofibular ligament injury is by far the commonest followed by combined anterior talofibular and calcaneofibular ligament strain. The posterior talofibular ligament is the strongest component of the lateral collateral ligament complex and is injured in severe ankle injury along with the other lateral collateral ligaments. While isolated calcaneofibular ligament strain has been reported, calcaneofibular ligament and posterior talofibular ligament strains with an intact anterior talofibular ligament are rare and reported in cadaveric studies. We present a case of radiologically diagnosed calcaneofibular ligament and posterior talofibular ligament injury and will discuss the anatomy, stress radiography, and magnetic resonance image findings and the mechanism of this particular injury.

Ankle Angle Prediction Using a Footwear Pressure Sensor and a Machine Learning Technique

Ankle injuries may adversely increase the risk of injury to the joints of the lower extremity and can lead to various impairments in workplaces. The purpose of this study was to predict the ankle angles by developing a footwear pressure sensor and utilizing a machine learning technique. The footwear sensor was composed of six FSRs (force sensing resistors), a microcontroller and a Bluetooth LE chipset in a flexible substrate. Twenty-six subjects were tested in squat and stoop motions, which are common positions utilized when lifting objects from the floor and pose distinct risks to the lifter. The kNN (k-nearest neighbor) machine learning algorithm was used to create a representative model to predict the ankle angles. For the validation, a commercial IMU (inertial measurement unit) sensor system was used. The results showed that the proposed footwear pressure sensor could predict the ankle angles at more than 93% accuracy for squat and 87% accuracy for stoop motions. This study confirmed that the proposed plantar sensor system is a promising tool for the prediction of ankle angles and thus may be used to prevent potential injuries while lifting objects in workplaces.

Toward Developing a Semiquantitative Whole Body-MRI Scoring for Juvenile Idiopathic Arthritis: Critical Appraisal of the State of the Art, Challenges, and Opportunities

With powerful new therapies available for management of juvenile idiopathic arthritis (JIA), early diagnosis leading to appropriate treatment may prevent long-term structural joint damage. Although magnetic resonance imaging (MRI) is typically used to assess individual body parts, indications for whole body (WB) MRI are increasing. Its utility as a diagnostic and monitoring tool has already been widely investigated in adult rheumatology patients, but less so in pediatric rheumatologic patients. This paper is a comprehensive review of scoring systems and a proposal for the conceptual development of a WB-MRI scoring system for the evaluation of JIA. In this review we identify, summarize, and critically appraise the available literature on the use of WB-MRI in inflammatory arthritis, addressing relevant considerations on components of a classification system that can lead to the development of a future pediatric WB-MRI scoring system for use in children with JIA. We also discuss advantages and challenges of developing such a WB-MRI scoring system for assessment of JIA and outline next steps toward the conceptual development of this scoring system.

Association between anterior talofibular ligament injury and ankle tendon, ligament, and joint conditions revealed by magnetic resonance imaging

Background

The lateral ankle ligament complex is the most frequently injured ligament secondary to strong ankle inversion movement during lateral ankle sprains (LAS). Among these injuries, anterior talofibular ligament (ATFL) injury is the most frequent condition (present in 66-85% of such injuries). The purpose of this research was to use magnetic resonance imaging (MRI) to determine the association between ankle tendon, ligament, and joint conditions and ATFL injuries.

Methods

A case-control MRI study was carried out to compare the presence of ankle muscle, tendon, ligament, and joint conditions in patients with injured ATFLs (case group; n=25) and non-injured ATFLs (control group; n=25).

Results

Achilles tendinopathy was present in 1/25 (4%) patients with injured ATFLs and 7/25 (28%) non-injured ATFL subjects (P=0.048). Injured calcaneofibular ligaments (CFLs) were present in 19/25 (76%) patients with injured ATFLs and 1/25 (4%) non-injured ATFL subjects (P<0.001). Finally, injured tibiotalar joints were present in 16/25 (64%) patients with injured ATFLs and 5/25 (20%) non-injured ATFL subjects (P=0.002). Other musculoskeletal structure injuries occurred at similar rates between patients with injured ATFLs and those with non-injured ATLFs (P≥0.05).

Conclusions

Patients with ATFL injuries showed a greater presence of CFL and tibiotalar joint injuries than subjects with non-injured ATFLs.

Magnetic resonance imaging of midtarsal sprain: Prevalence and impact on the time of return to play in professional soccer players

BACKGROUND

Ankle sprain is a common injury in professional soccer, but to date midtarsal sprain has not been investigated in this context. The purpose of this study was to determine the prevalence of midtarsal sprain by MRI and to assess its impact on the time of return to play in professional soccer players.

METHODS

We included 52 professional soccer players who underwent 59 MRI examinations after acute ankle trauma between January 2012 and September 2019. Images were retrospectively reviewed in consensus by two radiologists for assessment of midtarsal sprain and ankle sprain. Ligaments were graded as i) normal, ii) partial tear, or iii) complete tear. Time to return to play (RTP) for each athlete was retrieved from team medical records. A Kruskal-Wallis test and Dunn's pairwise tests were used to calculate differences in RTP time between groups with i) isolated midtarsal sprain, ii) isolated lateral ankle sprain, and iii) combined midtarsal and lateral ankle sprain.

RESULTS

MRI revealed isolated ankle sprain in 24 of 59 MRI examinations (40.6 %). Acute midtarsal ligament injury was present in 15 examinations (25.4 %). Four of the 15 examinations (26.7 %) had isolated midtarsal injuries and eleven of the 15 examinations (73.3 %) had concomitant ankle sprain. RTP time was 39 days (range 9-70 days) for isolated midtarsal sprain. RTP time was significantly higher for athletes with combined ankle and midtarsal sprain (47 days, range 15-74 days) when compared to athletes with isolated ankle sprain (24 days, range 2-59 days) (p = .019).

CONCLUSION

Our MRI study reveals that midtarsal sprain is a frequent injury in professional soccer players with ankle sprain. Midtarsal ligament findings on MRI combined with evidence of lateral ankle sprain is associated with a longer time of return to play compared to isolated lateral ligament injuries.

LEVEL OF EVIDENCE

Retrospective study, observational study.

Traumatic and non-traumatic bone marrow edema in ankle MRI: a pictorial essay

Bone marrow edema (BME) is one of the most common findings on magnetic resonance imaging (MRI) after an ankle injury but can be present even without a history of trauma. This article will provide a systematic overview of the most common disorders in the ankle and foot associated with BME.

The presence of BME is an unspecific but sensitive sign of primary pathology and may act as a guide to correct and systematic interpretation of the MR examination. The distribution of BME allows for a determination of the trauma mechanism and a correct assessment of soft tissue injury. The BME pattern following an inversion injury involves the lateral malleolus, the medial part of the talar body, and the medial part of the distal tibia. In other cases, a consideration of the distribution of BME may indicate the mechanism of injury or impingement. Bone in direct contact with a tendon may lead to alterations in the bone marrow signal where BME may indicate tendinopathy or dynamic tendon dysfunction. Changed mechanical forces between bones in coalition may lead to BME. Degenerative changes or minor cartilage damage may lead to subchondral BME. Early avascular necrosis, inflammation, or stress fracture may lead to more diffuse BME; therefore, a detailed medical history is crucial for correct diagnosis.

A systematic analysis of BME on MRI can help to determine the trauma mechanism and thus assess soft tissue injuries and help to differentiate between different etiologies of nontraumatic BME.

Lateral Ligament Instability: Review of Pathology and Diagnosis

PURPOSE OF REVIEW

Ankle sprains are a common injury that can lead to chronic lateral ankle instability resulting in pain, poor function, and decreased quality of life. The purpose of this review is to present information regarding injury mechanisms to the lateral ligaments of the ankle and the necessary steps to appropriately diagnose lateral ligament instability.

RECENT FINDINGS

The literature demonstrates that history and physical examination is often a reliable method for diagnosis of lateral ankle instability. In addition, imaging modalities are often used as adjuncts for diagnosis, especially when physical exam findings are equivocal. In summary, chronic lateral ligament instability of the ankle occurs secondary to failure of the lateral ligamentous complex. A focused physical examination to evaluate the anterior talofibular ligament, calcaneofibular ligament, and posterior talofibular ligament is necessary for diagnosis. Imaging modalities including plain radiographs, stress radiographs, and MRI are helpful for definitive diagnosis and to rule out other pathology.

Unsuspected Accessory Ossicle in Possible Sinus Tarsi Syndrome: The Value of Bone SPECT/CT

Three-phase bone scan was performed for evaluation of possible sinus tarsi syndrome in a 52-year-old man with chronic left ankle pain. MRI was initially read as unremarkable, and there was little symptomatic improvement after intra-articular anesthetic injection. The primary finding that appreciated only delayed bone SPECT/CT images was focal increased uptake associated with a well-corticated 8-mm bony fragment adjacent to the left calcaneus, thought to represent an accessory ossicle within the left sinus tarsi. The increased uptake suggested fracture or severe degenerative change of the ossicle, likely contributing to the patient's chronic pain.

Sinus Tarsi Syndrome: Diagnosed on 99mTc-MDP bone SPECT/CT

Sinus Tarsi Syndrome is a cause of chronic ankle instability and pain. MRI of the ankle has been the modality of choice for diagnosing the condition. However, SPECT-CT offers an alternate modality for diagnosing and evaluation of the condition. We present the case of a footballer who was suffering from chronic right leg pain despite receiving physiotherapy. He was being managed as a case of a chronic ankle sprain. Meanwhile, he was referred to the department as radiology for MRI of the ankle could not be performed as the patient felt claustrophobic. The patient subsequently underwent a ^99mTc-MDP Bone scan. He was diagnosed to be suffering from sinus tarsi syndrome as it showed a characteristic pattern noted on ^99mTc-MDP Bone scintigraphy. This case report reveals the potential of SPECT-CT as an alternative in the evaluation of chronic ankle sprain to MRI in segment of cases where MRI is not performed due to various reasons.

Impact of the T2-weighted axial oblique MRI sequence in the assessment of peroneal tendons

AIM

To define the role of the T2-weighted axial oblique sequence for the magnetic resonance imaging (MRI) assessment of peroneal tendon pathologies.

MATERIALS AND METHODS

Two radiologists interpreted 180 ankle MRI examinations using standard sequences alone and then in combination with an axial oblique sequence. The readers indicated how likely a peroneal pathology was present using a five-level confidence scale. Diagnostic confidence, interobserver agreement, and clinical correlation were compared. Changes in diagnosis were recorded.

RESULTS

For both readers, the diagnostic confidence was significantly higher using the axial oblique sequence for tendinosis and inframalleolar tenosynovitis for both tendons and for peroneus brevis partial and longitudinal split tears (p<0.001). For reader 1, the diagnostic confidence was also higher using the axial oblique sequence for peroneus longus partial tears (p=0.007). Changes in diagnosis were seen for tendinosis and tenosynovitis of both tendons and for peroneus brevis partial and longitudinal split tears in 0.6-10.8% of cases. Inter-rater reliability was significantly higher with the axial oblique sequence for the diagnosis of tendinosis, inframalleolar tenosynovitis, and partial tear for both tendons, and for peroneus brevis longitudinal split tear. Amongst 105 examinations with clinical information, peroneal pathologies were most frequently diagnosed as present in cases with lateral symptoms (17% versus 14%) and absent in cases without lateral symptoms (92% versus 86%) on the axial oblique sequence.

CONCLUSION

The axial oblique sequence for the assessment of peroneal tendons allows for higher diagnostic confidence, inter-rater reliability, and clinical correlation and can lead to changes in diagnosis.

Adventitious bursitis in the plantar fat pad of forefoot presenting as a tumoral mass

Adventitious bursitis of the plantar fat pad is a common cause of forefoot pain. It may develop at sites where subcutaneous tissue is exposed to friction and high pressure. In the forefoot, adventitious bursitis is usually adjacent to bony prominences of the metatarsal heads. Diagnosis and management of adventitious bursitis usually do not require imaging studies. However, the condition occasionally presents as a solid pseudotumoral mass requiring imaging. Magnetic resonance imaging (MRI) may demonstrate a heterogeneous mass with a solid component exhibiting intermediate to high signal intensity on T2-weighted images and thick nodular enhancement suggesting a neoplastic lesion. We report three cases of adventitious bursitis in patients who complained of a painful palpable mass on the forefoot, with a partially solid and enhancing component seen on MRI. In the first case, a biopsy was performed for the diagnosis of adventitious bursitis. The two other cases exhibited a solid component on MRI. However, a diagnosis of adventitious bursitis was suspected, and it was felt that a biopsy could be postponed. The spontaneous regression of the mass with relative discharge of the forefoot pressure confirmed the diagnosis. With these three cases, we illustrate the MR findings that could suggest adventitious bursitis despite the presence of a solid component and that may obviate the need for pathologic proof.

Master knot of Henry revisited: a radiologist's perspective on MRI

The master knot of Henry refers to a narrow space located between the anatomical crossover of the flexor hallucis longus and flexor digitorum longus tendons. This small space is prone to "intersection syndrome," as a result of tendinosis, tenosynovitis, and tears of the aforementioned tendons at the knot of Henry. The aim of this educational review is to detail the anatomy of the knot of Henry, including common variations in the tendon position and orientation. These complex interconnections can affect the outcome of surgical intervention if not appreciated at the time of treatment. We will also provide an overview of the common and rarer pathologies related to the knot of Henry. The aim of the present review is to make radiologists more aware of pathologies in this region, which are not routinely seen in daily practice.

Radiographic Presentation of Delayed Diagnosis of Charcot Foot in a 56-Year-Old Patient With No Reported History of Diabetes: A Case Report

Objective

The purpose of this case report is to describe the radiographic presentation of a patient with neuropathic osteoarthropathy.

Clinical Features

A 56-year-old white man presented to the diagnostic imaging department of a chiropractic teaching institution for the radiographic examination of the left foot. He had a 6-month history of left foot pain unresponsive to chiropractic care. The patient had reported no history of diabetes and denied any trauma, surgery, or malignancy.

Intervention and Outcome

Based upon the history, a 3-view radiographic examination of the left foot using computed radiography was performed. Radiographic abnormalities included osseous resorption, architectural foot disorganization, and dissociation and collapse of the anatomical alignment between the intertarsal and tarsal-metatarsal articulations. Intra-articular osseous debris formation with periarticular edema of the midfoot was noted. After the radiological diagnosis, the patient was subsequently investigated and diagnosed with type 2 diabetes mellitus. Thus, there were radiographic findings of poorly controlled or untreated diabetes mellitus with the resultant complication of neuropathic osteoarthropathy.

Conclusion

Some patients with type 2 diabetes may present with covert manifestations and other symptoms, such as a history of unexplained foot pain. The patient in this case with diabetes-induced neuropathic osteoarthropathy demonstrates that these findings should raise suspicion and result in an appropriate follow-up investigation.

Avascular necrosis: radiological findings and main sites of involvement - pictorial essay

The term avascular necrosis describes any one of a number of bone diseases that have a common mechanism: the death of bone components due to lack of blood supply. Avascular necrosis can occur in diverse parts of the skeleton, each location-specific form not only receiving a distinct designation but also presenting unique epidemiologic characteristics. However, the imaging findings are similar in all of the forms, which pass through well-described radiological phases, regardless of the site of involvement. Because avascular necrosis can cause considerable morbidity if not properly detected and managed, the radiologist plays a fundamental role. The present study provides a brief review of the main radiological aspects of the various forms of avascular necrosis, illustrated on the basis of a collection of cases from our institution.

Management of Chronic Achilles Tendon Injuries-Review of Current Protocols and Surgical Options

Chronic Achilles tendon injury is a challenging problem. A review of the different options available and their technical considerations is required. Reconstruction of the Achilles tendon depends on numerous factors such as the gap between the debrided tendon ends, the presence of a distal stump, and the and presence of scar tissue. Various protocols have been described for reconstruction. Methods of reconstruction vary from direct repair, bridging of the tendon gap with tendon grafts or tendon transfers. We review and enumerate the different protocols enumerated for the reconstruction of chronic Achilles tendon lesions in the literature and look at the authors preferred methods of reconstruction

Imaging Features of Avascular Necrosis of the Foot and Ankle

Avascular necrosis of the foot and ankle is a rare but important cause of pain and functional abnormality. This process may occur in any bone in the foot and ankle; however, it presents most often in characteristic locations. Understanding of key radiographic findings is important in management of these lesions. MRI is the most sensitive and specific method for detection and characterization of this abnormality.

Comparison of high resolution ultrasonography with clinical findings in patients with ankle pain

Aim: The aim of this study was to investigate the diagnostic accuracy of high resolution ultrasonography for the assessment of painful ankle joint as compared with the clinical findings. Material and Methods: A prospective study was conducted on 136 patients having history of ankle pain and referred to the Department of Radiodiagnosis and Imaging for ultrasonography. Statistical analysis: Comparison of ultrasonography findings and clinical findings was done using McNemar Test. Results: 136 patients with 218 pathologies of the ankle joint were analyzed. Of these, 178 pathologies were clinically suspected, but 206 were diagnosed with ultrasonography. This difference was statistically significant (p value = 0.000). Conclusion: Ultrasonography is an excellent tool for evaluating patients with ankle pain, especially in cases of lateral ligament pathologies, tendinous pathologies, joint effusion, and miscellaneous pathologies. It can be used as the primary imaging investigation because it allows a rapid, dynamic, and cost-effective examination of the ankle joint. However, ultrasonography has limitations when using it to evaluate a suspected posterior talofibular ligament injury, marrow abnormalities, and deep seated pathologies, for which MRI should be incorporated for a diagnosis.

Aim: The aim of this study was to investigate the diagnostic accuracy of high resolution ultrasonography for the assessment of painful ankle joint as compared with the clinical findings. Material and Methods: A prospective study was conducted on 136 patients having history of ankle pain and referred to the Department of Radiodiagnosis and Imaging for ultrasonography. Statistical analysis: Comparison of ultrasonography findings and clinical findings was done using McNemar Test. Results: 136 patients with 218 pathologies of the ankle joint were analyzed. Of these, 178 pathologies were clinically suspected, but 206 were diagnosed with ultrasonography. This difference was statistically significant (p value = 0.000). Conclusion: Ultrasonography is an excellent tool for evaluating patients with ankle pain, especially in cases of lateral ligament pathologies, tendinous pathologies, joint effusion, and miscellaneous pathologies. It can be used as the primary imaging investigation because it allows a rapid, dynamic, and cost-effective examination of the ankle joint. However, ultrasonography has limitations when using it to evaluate a suspected posterior talofibular ligament injury, marrow abnormalities, and deep seated pathologies, for which MRI should be incorporated for a diagnosis.

Imaging in Foot and Ankle Instability

This article reviews the imaging aspects relevant to ligamentous instabilities of the foot and ankle with a focus on MRI and ultrasound imaging. A pictorial review of the anatomy of the medial and lateral ankle ligaments, syndesmosis, spring ligament, Lisfranc complex, hallux sesamoid complex, and lesser toe plantar plate as seen on MRI is presented. Selected cases of ligamentous pathology relevant to foot and ankle instability are presented. The value of imaging in the assessment of foot and ankle instability is reviewed.

Normal Anatomy and Traumatic Injury of the Midtarsal (Chopart) Joint Complex: An Imaging Primer

The midtarsal (Chopart) joint complex consists of the talonavicular and calcaneocuboid joints and their stabilizing ligaments. Detailed assessment of this complex at MRI can be challenging owing to frequent anatomic variation and the small size of the structures involved. Nevertheless, a wide spectrum of pathologic conditions affect the joint complex, and its imaging evaluation deserves more thorough consideration. This review focuses on MRI evaluation of normal ligamentous anatomy and common variations about the Chopart joint, presenting practical imaging tips and potential diagnostic pitfalls. Imaging findings across a spectrum of traumatic Chopart joint injuries are also reviewed, from midtarsal sprains to Chopart fracture-dislocations. Midtarsal sprains-commonly associated with ankle inversion injuries-are emphasized, along with their often predictable radiographic and MRI injury patterns. Online DICOM image stacks are available for this article. ^©RSNA, 2018.

Insufficiency fractures: A rare cause of foot and ankle pain in three patients with rheumatoid arthritis

Insufficiency fractures are recognized but rare complications in patients with longstanding rheumatoid arthritis. Such fractures are typically solitary and are rarely seen to affect the foot and ankle. We describe 3 women with longstanding rheumatoid arthritis, treated with one, or a combination of, corticosteroids, DMARDs and anti-TNF, presenting with foot and ankle pain with no prior history of trauma. MRIs showed rare multiple florid insufficiency fractures of the foot and ankle, in 2 cases bilaterally, which were managed conservatively. These cases highlight the importance of considering insufficiency fractures in similar patients presenting with foot and ankle pain. Radiographs may fail to demonstrate these lesions, delaying diagnosis, and worsening patient outcome, therefore in such cases MRI is a valuable modality.

MRI evaluation of ligaments and tendons of foot arch in talar dome osteochondral lesions

Background There are no publications in literature describing an association between disorders of the ligaments and tendons supporting the foot arch and osteochondral lesions of the talus (OCLT). We believe there may be a correlation between the damage of these structures. Purpose To investigate the pathologies of main ligaments and tendons that support the foot arch in sprained ankles, by reviewing magnetic resonance imaging (MRI) studies and comparing the results in two groups of patients, with and without OCLT. Material and Methods MR images from 316 patients examined in the orthopedic clinic for ankle sprain were evaluated for pathologic findings of the plantar fascia, short and long plantar ligaments, spring ligament, sinus tarsi, and ankle tendons supporting the foot arch. Findings were compared between two groups of patients: 158 patients with OCLT and 158 patients without OCLT. Results Plantar fascia, short plantar ligament, and spring ligament abnormalities were seen in 50 (31.6%), 28 (17.7%), and 60 (38%) patients with OCLT, and in nine (5.6%), three (1.9%), and 18 (11.4%) patients without OCLT, respectively ( P < 0.05). Sinus tarsi and tendon abnormalities were seen in 11 (6.7%) and nine (5.7%) patients with OCLT, and in eight (5%) and eight (5%) patients without OCLT, respectively ( P > 0.05). Two or more associated abnormalities were present in 50 (31.6%) patients with OCLT and in 11 (6.7%) without OCLT ( P < 0.05). Conclusion Plantar fascia, short plantar ligament, and spring ligament abnormalities were commonly seen in patients with OCLT on MRI, while sinus tarsi and tendon abnormalities were not. Concomitant pathologies have an increased incidence in patients with OCLT.

Imaging of Chopart (Midtarsal) Joint Complex: Normal Anatomy and Posttraumatic Findings

OBJECTIVE

The objective of this article is to review the normal anatomy and posttraumatic findings of the Chopart joint complex. Key imaging features of the normal ligaments and patterns of ligamentous and osseous injuries are discussed.

CONCLUSION

Traumatic midtarsal injuries, particularly midtarsal sprain, are often overlooked clinically and on imaging but are relatively common and typically are associated with inversion ankle injuries. Radiologists should be familiar with Chopart joint anatomy and the imaging features of midtarsal injuries because early diagnosis may help optimize clinical management.

Subtalar instability: imaging features of subtalar ligaments on 3D isotropic ankle MRI

BACKGROUND

MRI analysis of subtalar ligaments in the tarsal sinus has not been well performed. We retrospectively investigated the appearance of subtalar ligaments using 3D isotropic MRI and compared imaging findings of subtalar ligaments between patients with subtalar instability (STI) and controls.

METHODS

Preoperative MRIs of 23 STI patients treated with arthroscopic subtalar reconstruction were compared to MRIs of 23 age- and sex-matched control subjects without STI. Thickness and width of anterior capsular ligament (ACL) and interosseous talocalcaneal ligament (ITCL) as well as thickness of calcaneofibular ligament (CFL) and anterior talofibular ligament (ATFL) were measured. Abnormalities in ACL, ITCL, CFL, ATFL, cervical ligament, and inferior extensor retinaculum were analyzed.

RESULTS

STI patients had significantly smaller ACL thickness and ACL width than controls (ACL thickness: 1.73 mm vs. 2.22 mm, p = 0.007; ACL width: 7.21 mm vs. 8.80 mm, p = 0.004). ACL thickness of ≤2.1 mm had a sensitivity of 66.7% and a specificity of 66.7% for diagnosis of STI. ACL width of ≤7.9 mm had a sensitivity of 80.0% and a specificity of 76.2% for the diagnosis of STI. However, thickness and width of ITCL, thickness of CFL, or thickness of ATFL was not significantly different between the two groups. Absence or complete tear of ACL was significantly more frequent in STI patients than that in controls (34.8% vs. 8.7%, p = 0.035). Complete tear of CFL and ATFL was more common in STI patients than that in controls, although the difference between the two groups was not statistically significant. Abnormalities of ITCL, cervical ligament, or inferior extensor retinaculum were not significantly different between the two groups.

CONCLUSIONS

MRI features of thin or narrow ACLs may suggest STI. Absence or complete tear of ACL was significantly more common in STI patients than that in controls.

Imaging of the spectrum of bony injuries in the diabetic foot: a case series with emphasis on non-Charcot fractures

Diabetes mellitus is associated with an increased risk of lower limb injuries. Peripheral neuropathy, often associated with diabetes, has been demonstrated to increase the risk of fracture almost two-fold and is associated with complications related to fracture healing. Detection of neuropathy-related foot injury is frequently delayed owing to the paucity of symptoms and low degree of suspicion by the clinician. Early recognition of fracture or bone injury and appropriate treatment are critical in preventing debilitating foot deformity and disability. Therefore, the astute radiologist cognizant of these potential injuries plays an essential role in early diagnosis of bony injuries in the diabetic foot. We present a series of radiological images that depict a range of osseous injuries in the diabetic foot and emphasize the role of the radiologist in early recognition of these abnormalities.

[MRI diagnostics of bone marrow oedema and its significance for the forensic medical evaluation of the injuries to bones and articulations]

The objective of the present study was the analysis of the publications in the literature dealing with radiological methods employed for the diagnostics of injuries to and diseases of the bones and articulations as well as the role of bone marrow oedema in the development of these conditions in the specific context of the problems facing forensic medical expertise. The main results of the domestic and foreign authors concerning MRI-based investigations into the nature of injuries and other pathological changes in bones and articulations during different periods after their development are discussed with the major emphasis placed on diagnostics of bone marrow oedema. Magnetic resonance visualization of this diagnostic feature and the related manifestations of the above conditions in many cases provides an indisputable evidence of the damage whereas the discovery of its distribution to and localization in the bone structures makes it possible to elucidate the sources of this condition, such as a blow, torsional stress, stretching, etc., and its underlying mechanisms. The character and the mode of distribution of the signal from a bone marrow oedema under various conditions of visualization allow to carry out differential diagnostics of the damage prescription period of up to 1.5 months.

Ultrasonography of the ankle joint

Ankle disorders are a relatively common pathological condition, and ankle injuries account for approximately 14% of sports-related orthopedic emergency visits. Various imaging modalities can be used to make a diagnosis in cases of ankle pain; however, ultrasound (US) has several benefits for the evaluation of ankle pain, especially in the tendons, ligaments, and nerves of the ankle. The purpose of this article is to review the common causes of ankle pathology, with particular reference to US features. In addition, the importance of a dynamic evaluation and a stress test with US is emphasized.

Adult-acquired flatfoot deformity

Adult-acquired flatfoot deformity (AAFD) is a known and recognized cause of pain and disability. Loss of PTT function is the most important contributor to AAFD, and its estimated prevalence is thought to be over 3%. This review aims to summarize the current literature and encompass recent advances regarding AAFD.