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Background: There is a paucity of literature describing MRI patterns of high ankle sprains in pediatric patients. Radiologists should understand MRI patterns of these injuries in both adults and children., Objective: To describe normal MRI appearance of pediatric syndesmotic ligaments and compare MRI patterns of high ankle sprains in children versus adults., Materials and Methods: We reviewed consecutive ankle MRIs performed over 3 years and divided them into three cohorts: a normal pediatric (≤16 years) cohort, and pediatric and adult cohorts with acute/subacute ankle syndesmosis injuries. Our retrospective review assessed interobserver agreement (Cohen kappa coefficient) and normal pediatric syndesmotic anatomy. We compared patterns of high ankle sprains (Fisher exact test) including ligament tears, periosteal stripping, avulsions and fractures., Results: Of the 582 ankle MRIs, we included 25 in the normal pediatric cohort, 20 in the pediatric injury cohort and 23 in the adult injury cohort. The anterior and posterior tibiofibular ligaments all attached to cortex or cartilaginous precursor, while the interosseous ligament/membrane complex attached to the fibrous periosteum in 22/25 (88%) normal pediatric cases. Tibial periosteal stripping at the interosseous ligament/membrane complex attachment occurred in 7/20 (35%) pediatric and 1/23 (4%) adult injury cases (P=0.02). No other statistically significant differences were found. Interobserver agreement ranged from kappa=0.46 to kappa=0.82 (ligament tears), 0.38 to 0.45 (avulsions) and 0.69 to 0.77 (periosteal stripping)., Conclusion: The normal interosseous ligament/membrane complex typically attaches to fibrous periosteum rather than bony cortex. Tibial periosteal stripping, usually without tibial fracture, is significantly more common among pediatric high ankle sprains. MRI patterns of high ankle sprains are otherwise not significantly different between children and adults., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

BACKGROUND. Tearing of the superior peroneal retinaculum is a known cause of peroneal tendon subluxation-dislocation. However, with the exception of cortical avulsions at the fibular attachment, superior peroneal retinaculum injury and subsequent peroneal tendon subluxation-dislocation are typically radiographically occult. OBJECTIVE. The purpose of this study was to evaluate the previously undescribed association between radiographic fibular tip periostitis and MRI evidence of peroneal tendon subluxation-dislocation in patients with hindfoot valgus. METHODS. Thirty-five patients with radiographic fibular tip periostitis and 35 ageand sex-matched individuals without periostitis were selected from among 220 consecutively registered patients with hindfoot valgus who had undergone both ankle radiography and MRI. Studies were retrospectively assessed by two musculoskeletal radiologists in consensus and by two additional blinded radiologists independently for the presence of peroneal tendon subluxation-dislocation, presence of subfibular impingement, and hindfoot valgus angle measurements. Interobserver agreement and accuracy, sensitivity, and specificity in the detection of fibular periostitis, peroneal tendon subluxation-dislocation, and subfibular impingement were calculated, and Fischer exact, Mann-Whitney, kappa coefficient, and intraclass correlation tests were performed. RESULTS. Both the consensus and the two independent interpretations showed that the frequency of peroneal tendon subluxation-dislocation was significantly greater in the group with periostitis (62.9%, 65.7%, and 85.7%) than in the group without periostitis (5.7%, 0%, and 14.3%) ( p < .001). The finding of periostitis was specific and highly sensitive for predicting peroneal tendon subluxation-dislocation. The frequency of subfibular impingement was also statistically higher in the group with periostitis than in the group without it ( p < .001). The hindfoot valgus angle was statistically larger in the group with periostitis than in the control group ( p = .01-.002) and among patients with versus those without peroneal tendon subluxation-dislocation ( p = .002 to p < .001). The blinded readers had substantial or almost perfect agreement on all imaging interpretations (concordance rate, 82.9-95.7%; κ = 0.66-0.91). CONCLUSION. The radiographic finding of fibular tip periostitis in patients with hindfoot valgus can be a predictor of peroneal tendon subluxation-dislocation and may also suggest advanced hindfoot valgus and subfibular impingement. These radiographic associations should be recognized by the radiologist, and MRI may be recommended as clinically indicated. CLINICAL IMPACT. Chronic undiagnosed peroneal tendon subluxation-dislocation can be a persistent cause of lateral ankle pain, leading to further degeneration and the possibility of complete peroneal tendon tears. Distal fibular periostitis in patients with hindfoot valgus can be a reliable radiographic indicator of this entity and may suggest the presence of subfibular impingement.

Normal skeletal development in the pediatric ankle is dynamic and often produces variable imaging appearances that are subject to misinterpretation. Radiologists must understand the underlying developmental phenomena, such as endochondral and membranous ossification and physeal fusion, and be familiar with their common and uncommon imaging manifestations unique to the pediatric ankle. This is especially true as the use of MRI in the evaluation of musculoskeletal trauma expands among younger populations. The authors focus on MRI evaluation of the skeletally maturing pediatric ankle and present pearls for accurately distinguishing normal findings and imaging pitfalls from true pathologic findings. The normal but often variable imaging findings of preossification, secondary ossification, and multiple ossification centers, as well as the range of bone marrow signal intensities that can be visualized within ossification centers, are described, along with tips to help differentiate these from true pathologic findings such as contusion, fracture, or tumor. The authors also review dynamic periosteal and physeal contributions to bone growth to highlight helpful distinguishing features and avoid misdiagnosis of common subperiosteal and periphyseal abnormalities. For example, the normal trilaminar appearance of the immature cortex and periosteum should not be mistaken for periosteal reaction, traumatic stripping, or subperiosteal hematoma. In addition, the physis can have several confusing but normal appearances, including normal physeal undulations (eg, Kump bump) or focal periphyseal edema, which should not be mistaken for pathologic findings such as physeal fracture, infection, or bar. © RSNA, 2020.

Objective: To report radiographic features and complications of coracoclavicular ligament reconstruction and the association of radiographic features with symptomatology., Materials and Methods: Retrospective picture archiving and communication system query (1/2012-8/2018) identified subjects with prior coracoclavicular ligament reconstruction. Post-operative radiographs were reviewed with attention to the following: (1) acromioclavicular alignment, (2) coracoclavicular width, (3) distal clavicular osteolysis, (4) osseous tunnel widening, and (5) hardware complication or fracture. Medical records were reviewed to determine purpose of imaging follow-up (symptomatic versus routine). Statistical analysis determined associations between binary features and outcomes, and inter-reader agreement., Result: Review of 55 charts identified 32 subjects (23 male, 9 females; age range 24-64; imaged 1-34 months following surgery) meeting inclusion criteria. Loss of acromioclavicular reduction was the most common imaging finding (n = 25, 78%), with 76% progressing to coracoclavicular interval widening. Distal clavicular osteolysis was seen in 21 cases (66%) and was significantly associated with loss of acromioclavicular joint reduction (p = 0.032). Tunnel widening occurred in 23 patients (82%) with more than one follow-up radiograph. Six (19%) had hardware complication or fracture. No radiographic feature or complication had significant correlation with symptomatology (p values 0.071-0.721). Inter-reader agreement was moderate to substantial for coracoclavicular interval widening and hardware complication, fair to substantial for tunnel widening, and fair to moderate for loss of acromioclavicular reduction and distal clavicular osteolysis., Conclusion: Loss of acromioclavicular joint reduction, coracoclavicular interval widening, distal clavicular osteolysis, and tunnel widening are common radiographic features after coracoclavicular ligament reconstruction; however, they do not necessarily correlate with symptomatology.

To listen to the podcast associated with this article, please select one of the following: iTunes or Google Play. OBJECTIVE. The purpose of this article is to describe Stener-like lesions of the superficial medial collateral ligament (sMCL) of the knee, which, to our knowledge, have not yet been reported in the radiologic literature. This lesion, defined as a distal tear with interposition of osseous or soft-tissue structures between the ligament and its tibial attachment, often requires surgical intervention. MATERIALS AND METHODS. Knee MRI examinations of grade 3 sMCL tears were identified via a search of department imaging and orthopedic case files of medial collateral ligament (MCL) tears for the period of January 2010-April 2017 using the keywords "complete MCL tear" or "near complete MCL tear." Two musculoskeletal radiologists reviewed the MRI examinations. The location of the sMCL tear, presence of a Stener-like lesion, associated ligamentous injuries, and surgical findings were recorded. RESULTS. Review of 65 knee MRI examinations identified 20 cases of distal tibial grade 3 sMCL tear. Of the distal tears, 12 (60%) were Stener-like lesions and six (30%) were borderline lesions. Of these 18 cases, 14 (78%) were associated with multiligament knee injury and nine (50%) underwent MCL repair or reconstruction. Ten of the 12 (83%) Stener-like lesions were displaced superficial to the pes anserinus and two (17%) were entrapped, one in a reverse Segond fracture and one in the femorotibial compartment. CONCLUSION. Stener-like lesions represent a high percentage of tibia-sided sMCL avulsions, are found most often with pes anserinus interposition, and are frequently associated with multiligamentous injury, suggesting high-energy trauma. MRI diagnosis is important because interposition preventing anatomic healing and potential secondary valgus instability often prompt surgical intervention.

The skeletal maturation of the shoulder has been well documented on radiographic and cadaveric studies. Recent increased use of MRI has provided increased understanding of the soft-tissue and osseous changes that occur during development. Thus recognizing normal maturation, imaging manifestations and pitfalls is crucial when evaluating the pediatric shoulder joint. At birth, the humeral diaphysis, midportion of the clavicle, and the body of the scapula are ossified, while the remainder of the bones of the shoulder are composed of non-ossified cartilaginous precursors. During growth, cartilaginous apophyses and epiphyses of the shoulder develop numerous secondary ossification centers, which fuse with the primary ossification centers to form the complete bony components of the shoulder. Additionally changes in the morphology of the growth plates as well as marrow signal occur in an organized manner. This paper affords the reader with an understanding of the normal development of three major components of skeletal maturation in the shoulder: ossification centers, growth plates and marrow signal. These topics are further subdivided into the glenoid, proximal humerus and acromioclavicular joint. We also provide a focus on distinguishing normal anatomy from imaging pitfalls related to skeletal maturation.

The focus of this article is to illustrate various pathologic entities and variants, heralding disease about the ankle, based on scrutiny of AP radiographs of the ankle, with correlative findings on cross-sectional imaging. Many of these entities can only be detected on the AP ankle radiograph and, if not recognized, may lead to delayed diagnosis and persistent morbidity to the patient. However, a vigilant radiologist, equipped with the knowledge of the characteristic appearance and typical locations of the imaging findings, should be able to make the crucial initial diagnosis and surmise additional findings to be confirmed on cross-sectional imaging., (Copyright © 2019 Elsevier Inc. All rights reserved.)

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.

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.

Objective: Injuries at the calcaneocuboid and talonavicular joint have been described as two distinct, unrelated entities in the radiology literature. Our purpose was to assess the coexistence of these injuries using radiography and MRI and to correlate our findings with radiologic and clinical diagnoses., Materials and Methods: Twenty-one patients with injury at the anterior calcaneal process on radiographs or MR images were retrospectively assessed for concomitant injury at the talonavicular joint. Radiologic and clinical diagnoses and treatment were documented. McNemar and kappa statistics were calculated; p values < 0.05 were considered statistically significant., Results: Radiographic and MRI rates of detection of injuries across the Chopart joint were statistically different. Calcaneocuboid avulsion fractures were evident on 48% of radiographs and 100% of MR images (p = 0.001). Talonavicular joint injuries were evident on 38% of radiographs and 76% of MR images (p = 0.008). Concomitant injury at both joints was evident on 14% of radiographs and 76% of MR images (p < 0.0001). Interrater agreement was 0.488-0.637 and 0.286-0.364 for talonavicular and 0.144-0.538 and 0.976-1 for calcaneocuboid injuries on radiography and MRI, respectively. Sixty percent of calcaneocuboid fractures were prospectively missed on radiography (none on MRI), whereas 38% and 25% of talonavicular findings were missed on radiography and MRI, respectively. Sixty percent of injuries were clinically misdiagnosed as ankle sprains. Chopart joint injury was never mentioned in prospective clinical or imaging diagnoses., Conclusion: Calcaneocuboid and talonavicular injuries commonly coexist. Radiographs underestimate severity of injury; MR images show more subtle abnormalities. Lack of mention of Chopart joint injury clinically and on imaging reports underlies the need for greater familiarity with this entity.

Objective: This study determined the frequency and MRI appearance of osseous and ligamentous injuries in midtarsal (Chopart) sprains and their association with ankle sprains after acute ankle injuries. Prospective diagnosis of and interobserver agreement regarding midtarsal injury among musculoskeletal radiologists were also assessed., Subjects and Methods: Two cohorts with ankle MRI were identified via a digital PACS search: patients who had undergone MRI within 8 weeks after ankle injury and control subjects who had not sustained ankle trauma. Studies were retrospectively reviewed in consensus as well as independently, assessing ligamentous and osseous injury to the Chopart joint (calcaneocuboid and talonavicular joints) and associated lateral collateral and deltoid ligamentous injury. Interobserver agreement was calculated, and prospective radiology reports were reviewed to determine the musculoskeletal radiologist's familiarity with Chopart joint injury., Results: MR images of control subjects (n = 16) and patients with ankle injury (n = 47) were reviewed. The normal dorsal calcaneocuboid and calcaneocuboid component of bifurcate ligaments were variably visualized; the remaining normal ligaments were always seen. Eleven patients (23%) had midtarsal ligamentous and osseous injury consistent with midtarsal sprain (eight acute or subacute, one probable, and two old). Six (75%) of eight acute or subacute cases had coexisting lateral collateral ligament injury. Eighty-nine percent of osseous injuries were reported prospectively, but 83% of ligamentous injuries were missed. Substantial interobserver agreement was achieved regarding diagnosis of midtarsal sprain., Conclusion: Midtarsal sprains are commonly associated with acute ankle injury and with ankle sprains. Presently, midtarsal sprains may be underrecognized by radiologists; thus, greater familiarity with the MRI spectrum of ligamentous and osseous injuries at the Chopart joint is important for accurate diagnosis and clinical management.

Objective: The bare spot (BaS) is a central, well-circumscribed focal defect in the glenoid articular surface, with reported adult incidence of 1-2%. We aimed to reassess MRI features of BaS in the pediatric population and determine its etiology., Materials and Methods: A retrospective search of our database from June 2014 to October 2015 was performed for shoulder MRI in patients between 5 and 25 years and then subdivided into four groups: group 1, 5-10 years; group 2, 10-15 years; group 3, 15-18 years; group 4, 20-25 years. BaS was defined as a well-marginated, central defect of increased signal in the articular surface of the glenoid, seen on at least two planes, without evidence of underlying glenoid pathology. Presence, location and size along with clinical indications were documented., Results: A final cohort of 253 patients revealed 23 BaS, 3.5% in group 1, 20% in group 2, 5% in group 3 and 4% in group 4. There was a significantly higher incidence in group 2 (p = 0.007) compared to group 3 and p = 0.002 compared to group 4. Location was mainly central. Mean size was significantly bigger in group 2 compared to group 3 and 4. Distribution showed the highest number at 14-15 years of age. Instability was higher in groups 3 and 4., Conclusion: Incidence of BaS in group 2 was significantly higher than in other age groups and higher than in adults. BaS was also larger compared to other populations. These findings support a developmental theory, explained by the centripetal ossification of the glenoid.

Purpose: To assess the MRI features of growth plate injury at the base of the coracoid process., Materials and Methods: Subjects were identified through retrospective search of our department imaging database and teaching files and the teaching files of two outside academic institutions. The coracoid base growth plate was examined with attention to widening, irregularity, abnormal signal intensity of the growth plate, and the presence of adjacent soft tissue edema. The apposing coracoid and scapular bony surfaces were examined for signal intensity and morphology., Results: Shoulder MRIs in eight patients with coracoid base growth plate disturbances were retrospectively reviewed (7 males, 1 female, mean age 15 years). Growth plate injury manifested as widening, irregularity and increased signal, apposing bony marrow edema and hypertrophy, and surrounding soft tissue edema. Five subjects were athletes (football, archery, basketball, swimming, rugby), two had a history of neuromuscular disorders, and one subject presented after a fall. Clinical indications included: rule out labral tear (n = 3), rule out rotator cuff tear or fracture after fall (n = 1), nonspecific pain (n = 1), shoulder subluxation, rule out glenoid pathology (n = 1, patient with underlying neuromuscular disorder), muscular dystrophy with shoulder pain (n = 1), and impingement (n = 1). Coracoid growth plate injury was not suspected clinically in any of the patients., Conclusion: Awareness of the imaging appearance of coracoid base growth plate injury can aid in a more accurate diagnosis of shoulder MRI studies in young pediatric athletes. While uncommon, coracoid growth plate injury should be considered when assessing children with shoulder symptomatology.

Stress fractures, including both fatigue and insufficiency types, are frequently encountered in clinical practice as a source of pain in both athletes and patients with predisposing conditions. Radiography is the imaging modality of choice for baseline diagnosis. MRI has greatly improved our ability to diagnose radiographically occult stress fractures. Tc-99m bone scan and CT may also be useful as diagnostic tools. Although fatigue and insufficiency fractures can be self-limited and go onto healing even without diagnosis, there is usually value in initiating prompt therapeutic measures as incomplete stress fractures have the potential of progressing to completion and requiring more invasive treatment or delay in return to activity. This is particularly important in the setting of stress fractures of the femoral neck. Accuracy in the identification of these injuries is also relevant because the differential diagnosis includes entities that would otherwise be treated significantly different (ie, osteoid osteoma, osteomyelitis, and metastasis). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment., (Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Chronic hip pain is a common clinical problem whose cause is often elucidated by imaging. The ACR Appropriateness Criteria for chronic hip pain define best practices of image ordering. Clinical scenarios are followed by the imaging choices and their appropriateness. The information is in ordered tables with an accompanying narrative explanation to guide physicians to order the right test. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment., (Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Osteoporosis is a considerable public health risk, with 50% of women and 20% of men >50 years of age experiencing fracture, with mortality rates of 20% within the first year. Dual x-ray absorptiometry (DXA) is the primary diagnostic modality by which to screen women >65 years of age and men >70 years of age for osteoporosis. In postmenopausal women <65 years of age with additional risk factors for fracture, DXA is recommended. Some patients with bone mineral density above the threshold for treatment may qualify for treatment on the basis of vertebral body fractures detected through a vertebral fracture assessment scan, a lateral spine equivalent generated from a commercial DXA machine. Quantitative CT is useful in patients with advanced degenerative bony changes in their spines. New technologies such as trabecular bone score represent an emerging role for qualitative assessment of bone in clinical practice. It is critical that both radiologists and referring providers consider osteoporosis in their patients, thereby reducing substantial morbidity, mortality, and cost to the health care system. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment., (Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Evaluation for suspected inflammatory arthritis as a cause for chronic extremity joint pain often relies on imaging. This review first discusses the characteristic osseous and soft tissue abnormalities seen with inflammatory arthritis and how they may be imaged. It is essential that imaging results are interpreted in the context of clinical and serologic results to add specificity as there is significant overlap of imaging findings among the various types of arthritis. This review provides recommendations for imaging evaluation of specific types of inflammatory arthritis, including rheumatoid arthritis, seronegative spondyloarthropathy, gout, calcium pyrophosphate dihydrate disease (or pseudogout), and erosive osteoarthritis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment., (Copyright © 2017 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Following a brief description of the normal anatomy and biomechanics of the midfoot, this article focuses on MR imaging features of common osseous, tendon, and ligament abnormalities that affect the midfoot. Discussion of the anatomy and pathology affecting the Chopart and Lisfranc joint complexes, both of which play important roles in linking the midfoot to the hindfoot and the forefoot respectively, is also included., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: To describe the post-surgical imaging appearance and complications of high tibial osteotomy in patients with the iBalance implant system (iHTO; Arthrex, Naples, FL, USA)., Materials and Methods: Retrospective, institutional review board-approved, Health Insurance Portability and Accountability Act-compliant review of imaging after 24 iBalance procedures was performed with attention to: correction of varus malalignment, healing at the osteotomy site, resorption of the osteoinductive compound, and complications., Results: Immediate correction of the varus deformity was present in all cases. Lobular radiolucency was present in all cases, more pronounced on the lateral knee radiograph, simulating infection or erosive disease. Four radiographic signs of healing were observed: blurring at the opposing osteotomy bony margins and at the osteoinductive compound and the adjacent bone interface, callus formation, and resorption of the osteoinductive compound. Complications were present in 33 % of cases, including fracture through the lateral tibial cortex (21 %), genu varum recurrence (8 %), painful exuberant bone formation (4 %), persistent pain, requiring total knee arthroplasty (4 %), and non-union (after >6 months' follow-up), with suspected infection (4 %)., Conclusion: Radiologists should be aware of the normal radiographic appearance following iBalance high tibial osteotomy, which may be confused with infection. Radiologists should also be aware of potential post-operative complications and compare all post-operative radiographs with the immediate post-operative examination to detect collapse of the osteotomy site and recurrence of varus angulation.

Objective: To assess, utilizing MRI, tarsal tunnel disease in patients with talocalcaneal coalitions. To the best of our knowledge, this has only anecdotally been described before., Materials and Methods: Sixty-seven ankle MRIs with talocalcaneal coalition were retrospectively reviewed for disease of tendons and nerves of the tarsal tunnel. Interobserver variability in diagnosing tendon disease was performed in 30 of the 67 cases. Tarsal tunnel nerves were also evaluated in a control group of 20 consecutive ankle MRIs., Results: Entrapment of the flexor hallucis longus tendon (FHL) by osseous excrescences was seen in 14 of 67 cases (21 %). Attenuation, split tearing, tenosynovitis, or tendinosis of the FHL was present in 26 cases (39 %). Attenuation or tenosynovitis was seen in the flexor digitorum longus tendon (FDL) in 18 cases (27 %). Tenosynovitis or split tearing of the posterior tibial tendon (PT) was present in nine cases (13 %). Interobserver variability ranged from 100 % to slight depending on the tendon and type of disease. Intense increased signal and caliber of the medial plantar nerve (MPN), indicative of neuritis, was seen in 6 of the 67 cases (9 %). Mildly increased T2 signal of the MPN was seen in 15 (22 %) and in 14 (70 %) of the control group., Conclusions: Talocalcaneal coalitions may be associated with tarsal tunnel soft tissue abnormalities affecting, in decreasing order, the FHL, FDL, and PT tendons, as well as the MPN. This information should be provided to the referring physician in order to guide treatment and improve post-surgical outcome.

There has been a rapid increase in the number of shoulder arthroplasties, including partial or complete humeral head resurfacing, hemiarthroplasty, total shoulder arthroplasty, and reverse total shoulder arthroplasty, performed in the United States over the past two decades. Imaging can play an important role in diagnosing the complications that can occur in the setting of these shoulder arthroplasties. This review is divided into two parts. The first part provides a general discussion of various imaging modalities, comprising radiography, CT, MRI, ultrasound, and nuclear medicine, and their role in providing useful, treatment-guiding information. The second part focuses on the most appropriate imaging algorithms for shoulder arthroplasty complications such as aseptic loosening, infection, fracture, rotator cuff tendon tear, and nerve injury. The evidence-based ACR Appropriateness Criteria guidelines offered in this report were reached via an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (the RAND/UCLA Appropriateness Method and the Grading of Recommendations Assessment, Development, and Evaluation) for rating the appropriateness of imaging and treatment procedures for specific clinical scenarios. Further analysis and review of the guidelines were performed by a multidisciplinary expert panel. In those instances in which there was insufficient or equivocal data for recommending the appropriate imaging algorithm, expert opinion may have supplemented the available evidence., (Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

Objective: To evaluate the position of the peroneus longus (PL) tendon relative to the cuboid tuberosity and cuboid tunnel during ankle dorsiflexion and plantarflexion using ultrasound and MRI., Materials and Methods: The study population included two groups: 20 feet of 10 asymptomatic volunteers who underwent prospective dynamic ultrasound and 55 ankles found through retrospective review of routine ankle MRI examinations. The location of the PL tendon at the cuboid tuberosity and cuboid tunnel was designated as completely within the tunnel, indeterminate, or subluxed with respect to ankle dorsiflexion and plantarflexion., Results: On dynamic ultrasound, the PL tendon was perched plantar to the cuboid tuberosity in dorsiflexion, and glided to enter the cuboid tunnel distal to the tuberosity in plantarflexion in all 20 feet. On the MRI evaluation, there was a statistically significant difference (p = 0.0006) in the location of the PL tendon between the ankles scanned in dorsiflexion and plantarflexion., Conclusion: Based on our findings on ultrasound and MRI, the PL tendon can glide in and out of the cuboid tunnel along the cuboid tuberosity depending on ankle position. Thus, "subluxation" of the tendon as it curves to enter the cuboid tunnel, which to the best of our knowledge has not yet been described, should be recognized as a normal, position-dependent phenomenon and not be reported as pathology.

Osteonecrosis of the hip (Legg-Calvé-Perthes) is a common disease, with 10,000-20,000 symptomatic cases annually in the United States. The disorder affects both adults and children and is most frequently associated with trauma and corticosteroid usage. The initial imaging evaluation of suspected hip osteonecrosis is done using radiography. MRI is the most sensitive and specific imaging modality for diagnosis of osteonecrosis of the hip. The clinical significance of hip osteonecrosis is dependent on its potential for articular collapse. The likelihood of articular collapse is significantly increased with involvement of greater than 30%-50% of the femoral head area, which is optimally evaluated by MRI, often in the sagittal plane. Contrast-enhanced MRI may be needed to detect early osteonecrosis of the hip in pediatric patients, revealing hypoperfusion. In patients with a contraindication for MRI, use of either CT or bone scintigraphy with SPECT (single-photon emission CT) are alternative radiologic methods of assessment. Imaging helps guide treatment, which may include core decompression, osteotomy, and ultimately, need for joint replacement. The ACR Appropriateness Criteria(®) are evidence-based guidelines for specific clinical conditions that are reviewed every three years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances in which evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment., (Copyright © 2016 American College of Radiology. Published by Elsevier Inc. All rights reserved.)

A growing number of magnetic resonance (MR) imaging studies of the shoulder are being performed as a result of greater and earlier participation of children and adolescents in competitive sports such as softball and baseball. However, scant information is available regarding the MR imaging features of the normal sequential development of the shoulder. The authors discuss the radiographic and MR imaging appearances of the normal musculoskeletal maturation patterns of the shoulder, with emphasis on (a) development of secondary ossification centers of the glenoid (including the subcoracoid and peripheral glenoid ossification centers); (b) development of preossification and secondary ossification centers of the humeral head and the variable appearance and number of the secondary ossification centers of the distal acromion, with emphasis on the formation of the os acromiale; (c) development of the growth plates, glenoid bone plates, glenoid bare area, and proximal humeral metaphyseal stripe; and (d) marrow signal alterations in the distal humerus, acromion, and clavicle. In addition, the authors discuss various imaging interpretation pitfalls inherent to the normal skeletal maturation of the shoulder, examining clues that may help distinguish normal development from true disease (eg, osteochondral lesions, labral tears, abscesses, fractures, infection, tendon disease, acromioclavicular widening, and os acromiale). Familiarity with the timing, location, and appearance of maturation patterns in the pediatric shoulder is crucial for correct image interpretation., (©RSNA, 2015.)

Objective: Acromial fusion may not be complete until age 18-25, making it questionable to diagnose os acromiale in adolescents. Os acromiale may exist in adolescents and can be differentiated from a developing acromial ossification center based on MRI findings., Materials and Methods: A total of 128 MRIs of the shoulder were randomly and blindly reviewed retrospectively by two musculoskeletal radiologists. The MRIs consisted of two groups: (1) 56 of os acromiale in adults (25-74 years old, mean, 50) and (2) 72 consecutive of adolescents (12-17 years old, mean, 14.5). The following were assessed at the interface between the distal acromion and os acromiale/developing ossification center(s): presence of os acromiale vs. developing acromion, orientation, margins, and edema within and adjacent to it., Results: Fifty-one adults and 49 adolescents were included. Exclusions were due to poor image quality or confounding findings (n = 7) or complete acromial fusion (n = 21 adolescents). Utilizing accepted definitions of os acromiale, all adult cases (100 %) were accurately diagnosed as os acromiale, with transverse interface orientation and irregular margins (94 %, R = 0.86, p < 0.00001). Forty-five (92 %) adolescent cases were accurately diagnosed as normally developing acromion with arched interface and lobulated margins (92 %, R = 0.92, p < 0.000001). Four (8 %) adolescent cases were diagnosed as having os acromiale, with transverse orientation and irregular margins. Thirty-five (69 %) and 46 (90 %) adults had marrow and interface edema, respectively. Six (12 %) and eight (16 %) adolescents had marrow and interface edema, respectively, including the four concluded to be os acromiale., Conclusions: Adolescents may have imaging findings consistent with os acromiale. The diagnosis of os acromiale should be based on imaging features and not limited by age.

Objective: To provide an MRI timeline of normal skeletal developmental patterns in the acromial process and distal clavicle in children up to 18 years of age., Materials and Methods: Retrospective review of all shoulder MRIs obtained at our institution between January 2003 and March 2012, in children up to age 18, was performed. When available, radiographs and CT scans for these children were also reviewed. The following variables of the distal acromion and clavicle, with attention to morphology and MRI signal, were assessed: (1) Chondro-osseous junction and (2) Development and fusion of the secondary ossification centers., Results: Ninety-eight children with 116 MR studies were identified from the data search. Of these, 13 patients were excluded and the final cohort included 85 children with 102 MRI studies. Forty-one of these patients also had shoulder radiographs. The cartilaginous precursors of the distal clavicle and acromion conformed to the final shape of these structures. The chondro-osseous interphases became progressively more lobulated and notched in the distal acromion and clavicle respectively. Appearance and fusion of the secondary ossification centers was significantly earlier in our study than previously reported. Acromial secondary ossification centers began forming at age 10 and clavicular ones, while uncommon, began forming at age 11. Fusion of acromial primary and secondary ossification centers began at age 14 and was generally complete after age 16., Conclusions: Based on MR imaging the development and fusion of the acromion and distal clavicle in children occur earlier than previously reported. They follow a sequential pattern and can serve as a blueprint for evaluating imaging studies of pediatric shoulders.

Objective: To assess the MRI appearance of normal skeletal development of the glenoid and glenoid-coracoid interface in the pediatric population. To the best of our knowledge, this has not yet been studied in detail in the literature., Materials and Methods: An IRB-approved, HIPAA-compliant retrospective review of 105 consecutive shoulder MRI studies in children, ages 2 months to 18 years was performed. The morphology, MR signal, and development of the following were assessed: (1) scapular-coracoid bipolar growth plate, (2) glenoid and glenoid-coracoid interface secondary ossification centers, (3) glenoid advancing osseous surface., Results: The glenoid and glenoid-coracoid interface were identified in infancy as a contiguous, cartilaginous mass. A subcoracoid secondary ossification center in the superior glenoid was identified and fused in all by age 12 and 16, respectively. In ten studies, additional secondary ossification centers were identified in the inferior two-thirds of the glenoid. The initial concavity of the glenoid osseous surface gradually transformed to convexity, matching the convex glenoid articular surface. The glenoid growth plate fused by 16 years of age. Our study, based on MRI, demonstrated a similar pattern of development of the glenoid and glenoid coracoid interface to previously reported anatomic and radiographic studies, except for an earlier development and fusion of the secondary ossification centers of the inferior glenoid., Conclusions: The pattern of skeletal development of the glenoid and glenoid-coracoid interface follows a chronological order, which can serve as a guideline when interpreting MRI studies in children.

Background: Bisphosphonate therapy for osteoporosis has been associated with atypical femoral fractures. To date, there have been few reports in the literature regarding the preoperative and postoperative courses of patients who have sustained bisphosphonate-associated complete atypical femur fractures., Objectives/purposes: The purposes of this study were to (1) characterize the preoperative course of patients who eventually presented with bisphosphonate-associated complete atypical femur fractures (duration of bisphosphonate treatment, pain history, risk of converting a nondisplaced fracture to a complete fracture); (2) evaluate the percentage of patients who achieved radiographic union of those fractures after treatment; and (3) determine the patients' recovery of function using the Short Musculoskeletal Functional Assessment., Methods: Thirty-three patients with 41 atypical, low-energy femur fractures associated with ≥ 5 years of bisphosphonate use were treated with intramedullary nailing between 2004 and 2011 at one center. The main outcome measurements were Short Musculoskeletal Functional Assessment for function and radiographic evaluation for fracture healing. Patients had been treated with bisphosphonates for an average of 8.8 years (range, 5-20 years) before presentation., Results: Patients reported a mean of 6 months of pain before presentation (range, 1-8 months). Sixty-six percent of patients with surgically treated complete fractures became pain-free and 98% were radiographically healed by 12 months. Sixty-four percent of patients who underwent intramedullary nailing reported a functional return to baseline within 1 year. Patients who reported major functional limitations at latest followup listed pain and apprehension as the major causes of their limitation., Conclusions: Patients with surgically treated bisphosphonate-associated complete femur fractures achieved generally reliable although delayed fracture healing if malaligned, and nearly two-thirds of patients returned to self-reported baseline function within 1 year., Level of Evidence: Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Recent advances in magnetic resonance (MR) imaging have revolutionized peripheral nerve imaging and made high-resolution acquisitions a clinical reality. High-resolution dedicated MR neurography techniques can show pathologic changes within the peripheral nerves as well as elucidate the underlying disorder or cause. Neurogenic pain arising from the nerves of the pelvis and lumbosacral plexus poses a particular diagnostic challenge for the clinician and radiologist alike. This article reviews the advances in MR imaging that have allowed state-of-the-art high-resolution imaging to become a reality in clinical practice., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Injuries to the extensor compartment of the ankle are uncommon and often are overlooked or misinterpreted at clinical presentation. Ultrasonography (US) and magnetic resonance (MR) imaging play a critical role in the diagnosis and evaluation of these injuries. US is a dynamic, quick, cost-effective imaging method for assessing ankle extensor compartment injuries as an alternative or adjunct to MR imaging. MR imaging provides multiplanar cross-sectional delineation of regional anatomic structures and also can be used to assess the predisposing cause, estimate the extent of injury, and aid in preoperative planning for requisite surgical repair. The spectrum of pathologic conditions affecting the ankle extensor compartment ranges from tendinosis secondary to degenerative, inflammatory, or depositional disease to traumatic tendon or retinacular rupture and entrapment neuropathy. Major components of the ankle extensor compartment at risk for injury include the anterior tibial, extensor hallucis longus, and extensor digitorum longus tendons; the extensor retinacular mechanism; and the anterior tarsal tunnel. Familiarity with the normal anatomic appearance and pathologic features of the ankle extensor compartment at US and MR imaging as well as potential imaging pitfalls is critical for accurate injury evaluation.

Tendon disorders along the plantar aspect of the foot may lead to significant symptoms but are often clinically misdiagnosed. Familiarity with the normal anatomy of the plantar tendons and its appearance at magnetic resonance (MR) imaging and ultrasonography (US) is essential for recognizing plantar tendon disorders. At MR imaging, the course of the plantar tendons is optimally visualized with dedicated imaging of the midfoot and forefoot. This imaging should include short-axis images obtained perpendicular to the long axis of the metatarsal shafts, which allows true cross-sectional evaluation of the plantar tendons. Normal plantar tendons appear as low-signal-intensity structures with all MR sequences. At US, accurate evaluation of the tendons requires that the ultrasound beam be perpendicular to the tendon. The normal tendon appears as a compact linear band of echogenic tissue that contains a fine, mixed hypoechoic and hyperechoic internal fibrillar pattern. Tendon injuries can be grouped into six major categories: tendinosis, peritendinosis, tenosynovitis, entrapment, rupture, and instability (subluxation or dislocation) and can be well assessed with both MR imaging and US. The radiologist plays an important role in the diagnosis of plantar tendon disorders, and recognizing their imaging appearances at MR imaging and US is essential.

Objective: To describe the outcomes for patients treated at a single institution, who sustained incomplete bisphosphonate-induced femoral fractures., Design: Retrospective review., Setting: University-based academic medical center., Patients: Thirty-one patients with 43 incomplete fractures met the inclusion criteria., Intervention: Nonoperative management or surgical intervention for fractures with refractory symptoms or progression of fracture lucency on radiographs., Main Outcome Measurements: Radiographic assessments and the Short Musculoskeletal Functional Assessment to gauge functional status., Results: The cohort was all women with an average age of 69.2 (range: 46-92) years and had been treated with bisphosphonate therapy for an average of 9.1 (range: 5-20) years. The average healing time for all incomplete fractures was 9.4 (range: 1.5-36) months. Forty-nine percent of the fractures (21 of 43 fractures) were ultimately treated with surgery for impending complete fracture or failure of nonsurgical management. Of the incomplete fractures treated with surgery, 81% became pain free and 100% were radiographically healed at a mean of 7.1 (range: 1.5-12) months. In contrast, of the nonoperatively treated incomplete fractures, only 64% were pain free at latest follow-up, with only 18% of fractures demonstrating radiographic evidence of healing at an average of 11 (range: 6-24) months. Standardized dysfunction index from the Short Musculoskeletal Functional Assessment was better (19.7) in the surgical group than in the nonsurgical group (19.7 vs. 25.7, P = 0.0017)., Conclusions: A higher percentage of patients treated surgically became asymptomatic and demonstrated radiographic evidence of healing earlier than those treated nonsurgically. Surgical intervention is effective for relief of symptoms when treating incomplete bisphosphonate-related femur fractures, and patients should be counseled to the potential benefits of prophylactic surgery., Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Objective: To elucidate the effects of prolonged bisphosphonate (BP) exposure on the development of atypical fragility fractures, and to define the associated risk factors., Methods: Approval was obtained from the institutional review board, and a retrospective chart analysis was performed on 51 patients who had been on BPs for at least 3 years and had complete subtrochanteric or diaphyseal femoral fracture(s) between January 2005 and April 2011. All relevant data were available for 25 patients (mean age, 67.52 years). All fractures included in the study were low- or no-energy. Relevant clinical and demographic data were collected regarding age, gender, ethnicity, height, weight, and comorbid medical conditions. Imaging and laboratory data collected on all patients included: calcium, alkaline phosphatase, 25-hydroxyvitamin D (25-OHD), intact parathyroid hormone, serum c-telopeptide, and urine n-telopeptide levels, bone mineral density, radiography, and magnetic resonance imaging., Results: Most of the patients in this study were Caucasian, were on alendronate, had bilateral findings, and almost half had prodromal symptoms. The 25-OHD level was suboptimal (<30 ng/mL) in 45.8% of the patients. Mean BP duration was 9.84 years, and mean bone density was in the osteopenic, not osteoporotic, range., Conclusion: Characteristics of patients with atypical BP-related fracture include relatively young age, long duration of BP use, suboptimal 25-OHD level, and bone density in the nonosteoporotic range. All of these may be significant risk factors for insufficiency fracture development.

Objective: The purpose of this article is to review the clinical and imaging features as well as the potential complications of hip dysplasia in the young adult. Hip dysplasia is an important cause of secondary osteoarthrosis, which accounts for a significant proportion of patients requiring total hip arthroplasty. The radiographic diagnosis of mild hip dysplasia in the young adult may be subtle and is primarily based on the detection of deficient coverage of the femoral head by the acetabulum., Conclusion: Cross-sectional imaging, including CT and MRI, afford improved detection and characterization by providing morphologic information about acetabular deficiency. MRI also allows evaluation of potential associated injuries to the articular cartilage, the labrum, and the ligamentum teres. Familiarity with the radiographic and cross-sectional imaging findings of mild hip dysplasia in the young adult may allow a timely diagnosis and implementation of treatment strategies, which may prevent or delay the development of early osteoarthritis.

Objective: The objective of our study was to investigate the association between high fovea capitis (fovea alta) and hip dysplasia in young adults., Materials and Methods: In a retrospective study, blinded observers reviewed 82 pelvic radiographic and hip MRI studies of three groups of patients: those with developmental dysplasia of the hip (DDH) (center-edge angle, ≤20°), those with borderline DDH (center-edge angle, 21°-25°), and control patients (center-edge angle, >25°). The center-edge angle and coxa valga (femoral neck-shaft angle, >135°) were assessed on pelvic radiographs, and fovea alta was assessed on MR images (delta angle, ≤10°). The Mann-Whitney and Fisher exact tests were used to correlate fovea alta with DDH and with coxa valga, respectively. Interobserver agreement for center-edge and delta angles and the diagnostic performance of fovea alta as a marker of DDH were calculated., Results: Thirty-one patients with DDH, 23 with borderline DDH, and 28 without DDH were included. Excellent interobserver agreement was found for center-edge angle (concordance correlation coefficient, 0.94) and for delta angle (concordance correlation coefficient, 0.91). Fovea alta had a significant association with DDH (p<0.001) but no association with coxa valga (p>0.57). A significant difference (p<0.001) was found between patients with DDH (3.4°) and those without DDH (21.7°) with respect to mean delta angle measurements. Fovea alta had 69.4% sensitivity, 82.1% specificity, 67.2% positive predictive value, 81.0% negative predictive value, and 75.6% overall accuracy as an indicator of DDH., Conclusion: Fovea alta shows promise as a strong MRI marker of DDH.

Objective: The purpose of our study was to determine the frequency and imaging features of atypical femoral fractures in a consecutive asymptomatic patient population on long-term bisphosphonate treatment and search for distinguishing clinical and laboratory parameters in the subset of patients with fractures., Subjects and Methods: Two hundred femoral radiographs in 100 asymptomatic patients (93 women and seven men; age range, 47-94 years; mean age, 69.3 years) were prospectively reviewed by two radiologists. All patients had received bisphosphonate treatment for at least 3 years and had no history of pain or recent trauma. MRI studies were performed when a fracture was suspected on radiographs. Bone mineral density, serum calcium, albumin, 25-hydroxy vitamin D, intact parathyroid hormone (iPTH), serum C-telopeptide, and urine N-telopeptide values were obtained., Results: Two of 100 patients (2%) had three insufficiency fractures. Both patients, 50 and 57 years old, were white, active, and had been receiving bisphosphonate therapy for 8 years. The patient with bilateral atypical femoral fractures showed typical features of bisphosphonate-related incomplete atypical femoral fractures. MRI confirmed the radiographic findings in both patients. The two patients with incomplete atypical femoral fractures were significantly younger than those without atypical femoral fractures. There were no significant differences among the fracture and nonfracture groups in terms of clinical or laboratory results, except for mean iPTH, which was significantly decreased in the fracture group., Conclusion: The 2% frequency of incomplete atypical femoral fractures in asymptomatic patients on long-term bisphosphonate therapy is higher than suggested in the literature. Aside from age and mean iPTH, there were no significant differences in clinical or laboratory data between the two groups.

Objective: Many disorders produce similar or overlapping patterns of bone marrow edema in the ankle. Bone marrow edema may present in a few hindfoot bones simultaneously or in a single bone. The purpose of this pictorial essay is to provide guidelines based on clinical history and specific MRI patterns and locations to accurately identify the cause of ankle bone marrow edema. We will first focus on bone marrow edema in general disease categories involving multiple bones, such as reactive processes, trauma, neuroarthropathy, and arthritides. A discussion of bone marrow edema in individual bones of the ankle and hindfoot including the tibia, fibula, talus, and calcaneus will follow. Helpful hints for arriving at the correct diagnosis will be provided in each section., Conclusion: After review of this article, radiologists should be able to use their knowledge of clinical history and specific MRI patterns and locations to accurately distinguish between the various causes of bone marrow edema in the ankle and hindfoot.

Objective: The objective of our study was to evaluate the diagnostic utility of conventional radiography for diagnosing bisphosphonate-related atypical subtrochanteric femoral fractures., Materials and Methods: Retrospective interpretation of 38 radiographs of complete subtrochanteric and diaphyseal femoral fractures in two patient groups-one group being treated with bisphosphonates (19 fractures in 17 patients) and a second group not being treated with bisphosphonates (19 fractures in 19 patients)-was performed by three radiologists. The readers assessed four imaging criteria: focal lateral cortical thickening, transverse fracture, medial femoral spike, and fracture comminution. The odds ratios and the sensitivity, specificity, and accuracy of each imaging criterion as a predictor of bisphosphonate-related fractures were calculated. Similarly, the interobserver agreement and the sensitivity, specificity, and accuracy of diagnosing bisphosphonate-related fractures (i.e., atypical femoral fractures) were determined for the three readers., Results: Among the candidate predictors of bisphosphonate-related fractures, focal lateral cortical thickening and transverse fracture had the highest odds ratios (76.4 and 10.1, respectively). Medial spike and comminution had odd ratios of 3.8 and 0.63, respectively. Focal lateral cortical thickening and transverse fracture were also the most accurate factors for detecting bisphosphonate-related fractures for all readers. The sensitivity, specificity, and overall accuracy for diagnosing bisphosphonate-related fractures were 94.7%, 100%, and 97.4% for reader 1; 94.7%, 68.4%, and 81.6% for reader 2; and 89.5%, 89.5%, and 89.5% for reader 3, respectively. The interobserver agreement was substantial (κ > 0.61)., Conclusion: Radiographs are reliable for distinguishing between complete femoral fractures related to bisphosphonate use and those not related to bisphosphonate use. Focal lateral cortical thickening and transverse fracture are the most dependable signs, showing high odds ratios and the highest accuracy for diagnosing these fractures.

Objective: The objective of this study was to describe the anatomy and MR appearance of the spring ligament recess of the talocalcaneonavicular joint., Subjects and Methods: Forty-nine MR examinations of the ankle with a spring ligament recess were prospectively collected. The size of the recess was measured. The presence of the following variables was recorded: talocalcaneonavicular joint effusion, ankle joint effusion, talar head impaction, acute lateral ankle sprain, chronic lateral ankle sprain, spring ligament tear, sinus tarsi ligament tear, talar dome osteochondral injury, and talonavicular osteoarthrosis. The Fisher exact test was performed to quantify the association of the talocalcaneonavicular effusion with the other variables. MR arthrography and dissection with histologic analysis were performed in two cadaveric ankles., Results: Twenty-four men and 25 women (average age, 39 years; range, 21-77 years) were included in the study. The average size of the fluid collection was 0.4 × 0.8 cm (range, 0.2-0.9 × 0.4-1.5 cm). The prevalence of the measured variables was talocalcaneonavicular joint effusion, 67.3%; ankle joint effusion, 61.2%; talar head impaction, 32.7%; acute lateral ankle sprain, 28.6%; chronic lateral ankle sprain, 59.2%; spring ligament tear, 14.3%; sinus tarsi ligament tear, 12.2%; talar dome osteochondral lesion, 20.4%; and talonavicular osteoarthrosis, 18.4%. There was a higher prevalence of talar head impaction among individuals with talocalcaneonavicular joint effusion (p = 0.0522). Cadaveric study revealed communication between the talocalcaneonavicular joint and the spring ligament recess., Conclusion: The spring ligament recess is a synovium-lined, fluid-filled space that communicates with the talocalcaneonavicular joint. The recess should be distinguished from a tear of the plantar components of the spring ligament.

Objective: The purpose of this study was to describe the MRI features of cortical desmoids associated with acute trauma., Conclusion: Marrow edema, periostitis, and adjacent soft-tissue edema can be seen in cases of cortical desmoid associated with acute trauma.

Objective: The objective of this article is to review the pathophysiology and clinical presentation of impingement syndromes at the ankle joint (anterolateral, anterior, anteromedial, posteromedial, and posterior) and the role of MRI in evaluating impingement at the ankle joint and at extraarticular locations, lateral to the ankle joint (talocalcaneal and calcaneofibular)., Conclusion: MRI is valuable in assessing both osseous and soft-tissue abnormalities associated with impingement syndromes.

Entrapment neuropathies of the knee, leg, ankle, and foot are often underdiagnosed, as the results of clinical examination and electrophysiologic evaluation are not always reliable. The causes of most entrapment neuropathies in the lower extremity may be divided into two major categories: (a) mechanical causes, which occur at fibrous or fibro-osseous tunnels, and (b) dynamic causes related to nerve injury during specific limb positioning. Magnetic resonance (MR) imaging, including high-resolution MR neurography, allows detailed evaluation of the course and morphology of peripheral nerves, as well as accurate delineation of surrounding soft-tissue and osseous structures that may contribute to nerve entrapment. Familiarity with the normal MR imaging anatomy of the nerves in the knee, leg, ankle, and foot is essential for accurate assessment of the presence of peripheral entrapment syndromes. Common entrapment neuropathies in the knee, leg, ankle, and foot include those of the common peroneal nerve, deep peroneal nerve, superficial peroneal nerve, tibial nerve and its branches, and sural nerve.

Entrapment neuropathies can manifest with confusing clinical features and therefore are often underrecognized and underdiagnosed at clinical examination. Historically, electrophysiologic evaluation has been considered the mainstay of diagnosis. Today, cross-sectional imaging, particularly magnetic resonance (MR) imaging and specifically MR neurography, plays an increasingly important role in the work-up of entrapment neuropathies. MR imaging is a noninvasive operator-independent technique that allows identification of the underlying cause of injury, differentiation between surgically treatable and untreatable causes, and guidance of selective diagnostic anesthetic nerve blocks. Pathologic conditions affecting the lumbosacral plexus and major motor and mixed nerves of the pelvis and hip include neuropathies of the lumbosacral plexus, femoral nerve, lateral femoral cutaneous nerve, obturator nerve, and sciatic nerve; piriformis muscle syndrome; and injury of the gluteal nerves. Diagnosis of entrapment neuropathies of the pelvis and hip with MR imaging requires familiarity with the normal MR imaging anatomy and awareness of the anatomic and pathologic factors that put peripheral nerves at risk for injury.

Objective: A paradoxical association between long-term alendronate therapy and low-energy subtrochanteric femoral fractures has been recently recognized. A retrospective review of 34 such femoral fractures was performed., Conclusion: Subtrochanteric femoral fractures associated with long-term alendronate therapy present with minimal trauma, may be chronic, and when incomplete may be missed. The characteristic imaging features include initial involvement and focal thickening of the lateral cortex, transverse orientation, medial beak, and superior displacement and varus angulation at the fracture site.

Objective: The objective of this study was to assess the prevalence of increased signal intensity in the pronator quadratus in the general patient population. Using region-of-interest measurements, we measured the signal intensity of the pronator quadratus and of an adjacent flexor muscle. In addition, we performed independent subjective assessments of the pronator quadratus., Conclusion: Increased signal intensity in the pronator quadratus is a frequent normal finding of unclear etiology and is not related to disease. Familiarity with this normal phenomenon is important to avoid overdiagnosis of denervation due to anterior interosseous nerve entrapment.