Correction to: Distal insertional anatomy of the triceps brachii muscle: MRI assessment in cadaveric specimens employing histologic correlation and Play-doh® models of the anatomic findings

Figures 9, 10, 11, 12 and 15 corrected.

Accessory anterolateral talar facet associated with tarsal coalition: prevalence and cross-sectional characterization

OBJECTIVE

The accessory anterolateral talar facet (AALTF) is a developmental entity described as a potential cause for rigid, painful flat foot. This study evaluates the possible association between the AALTF and other flat foot etiologies, specifically different types of tarsal coalitions.

MATERIALS AND METHODS

We evaluated patients with tarsal coalition or sinus tarsi syndrome for an AALTF on CT and MRI. Exclusion criteria included acute ankle trauma, recent surgery, motion or metal artifacts. We evaluated the AALTF length and height, and the lateral talocalcaneal structures for associated findings. The presence of calcaneonavicular (CNC), intra-articular middle facet talocalcaneal (MFTCC), posterior facet talocalcaneal (PFTCC), extra-articular posteromedial talocalcaneal (EATCC) and other rare coalitions were also evaluated.

RESULTS

One hundred eighty-seven patients were included (age range 14-91 years; mean ± SD; 50 ± 17 years). The AALTF prevalence in the study population was 31.55% (59/187), 40.91% in men, and 23.23% in women. The AALTF average length was 4.5 ± 1.1 mm, and average height was 8.9 ± 3.4 mm. The AALTF was found to be significantly associated with lateral talocalcaneal osseous changes such as cortical thickening and cystic changes (34/59 and 24/59 respectively, P < 0.01). The AALTF was also found to be significantly associated with sinus tarsi edema on MRI (45/52, P < 0.05). The AALTF was also significantly associated with EATCC (19/59, P < 0.01) and MFTCC (7/59, P < 0.05). No significant association was found with CNC, PFTCC or other rare coalitions.

CONCLUSION

The AALTF is common and significantly associated with some tarsal coalitions, specifically EATCC and MFTCC. When an AALTF or coalition is identified, special attention should be made to evaluate for other associated pathologies, as this could potentially affect management.

Flexor carpi radialis brevis: a rare accessory muscle presenting as an intersection syndrome of the wrist

The flexor carpi radialis brevis (FCRB) is a rare accessory muscle of the forearm and wrist. It is typically asymptomatic, but has been discovered either incidentally during cadaveric studies or at the time of surgery in patients with distal forearm injury. Rarely, the FCRB muscle is associated with pain. We report a patient with wrist pain related to intersection between the tendon of the FCRB muscle and the tendon of the flexor carpi radialis (FCR) muscle, with an associated longitudinal split tear of the FCR tendon, documented by magnetic resonance imaging (MRI). To our knowledge, this is only the second report in the English literature of this intersection syndrome.

Classification criteria for diffuse idiopathic skeletal hyperostosis: a lack of consensus

Objectives

DISH is a condition characterized by flowing ossifications of the spine with or without ossifications of entheses elsewhere in the body. Studies on the prevalence and pathogenesis of DISH use a variety of partly overlapping combinations of classification criteria, making meaningful comparisons across the literature difficult. The aim of this study was to systematically summarize the available criteria to support the development of a more uniform set of diagnostic/classification criteria.

Methods

A search was performed in Pubmed, Embase, Cochrane Library and Web of Science using the term DISH and its synonyms. Articles were included when two independent observers agreed that the articles proposed a new set of classification criteria for DISH. All retrieved articles were evaluated for methodological quality, and the presented criteria were extracted.

Results

A total of 24 articles met the inclusion criteria. In all articles, spinal hyperostosis was required for the diagnosis of DISH. Peripheral, extraspinal manifestations were included as a (co-)requirement for the diagnosis DISH in five articles. Most discrepancies revolved around the threshold for the number of vertebral bodies affected and to defining different developmental phases of DISH. More than half of the retrieved articles described a dichotomous set of criteria and did not consider the progressive character of DISH.

Conclusion

This systematic review summarizes the available different classification criteria for DISH, which highlights the lack of consensus on the diagnosis of (early) DISH. Consensus criteria, including consecutive phases of new bone formation that characterize DISH, can be developed based upon established diagnostic/classification criteria.

Acute and Stress-related Injuries of Bone and Cartilage: Pertinent Anatomy, Basic Biomechanics, and Imaging Perspective

Bone or cartilage, or both, are frequently injured related to either a single episode of trauma or repetitive overuse. The resulting structural damage is varied, governed by the complex macroscopic and microscopic composition of these tissues. Furthermore, the biomechanical properties of both cartilage and bone are not uniform, influenced by the precise age and activity level of the person and the specific anatomic location within the skeleton. Of the various histologic components that are found in cartilage and bone, the collagen fibers and bundles are most influential in transmitting the forces that are applied to them, explaining in large part the location and direction of the resulting internal stresses that develop within these tissues. Therefore, thorough knowledge of the anatomy, physiology, and biomechanics of normal bone and cartilage serves as a prerequisite to a full understanding of both the manner in which these tissues adapt to physiologic stresses and the patterns of tissue failure that develop under abnormal conditions. Such knowledge forms the basis for more accurate assessment of the diverse imaging features that are encountered following acute traumatic and stress-related injuries to the skeleton. (©) RSNA, 2016.

Utilization of CT scanning associated with complex spine surgery

Background

Due to the risk associated with exposure to ionizing radiation, there is an urgent need to identify areas of CT scanning overutilization. While increased use of diagnostic spinal imaging has been documented, no previous research has estimated the magnitude of follow-up imaging used to evaluate the postoperative spine.

Methods

This retrospective cohort study quantifies the association between spinal surgery and CT utilization. An insurance database (Humana, Inc.) with ≈ 19 million enrollees was employed, representing 8 consecutive years (2007–2014). Surgical and imaging procedures were captured by anatomic-specific CPT codes. Complex surgeries included all cervical, thoracic and lumbar instrumented spine fusions. Simple surgeries included discectomy and laminectomy. Imaging was restricted to CT and MRI. Postoperative imaging frequency extended to 5-years post-surgery.

Results

There were 140,660 complex spinal procedures and 39,943 discectomies and 49,889 laminectomies. MRI was the predominate preoperative imaging modality for all surgical procedures (median: 80%; range: 73–82%). Postoperatively, CT prevalence following complex procedures increased more than two-fold from 6 months (18%) to 5 years (≥40%), and patients having a postoperative CT averaged two scans. For simple procedures, the prevalence of postoperative CT scanning never exceeded 30%.

Conclusions

CT scanning is used frequently for follow-up imaging evaluation following complex spine surgery. There is emerging evidence of an increased cancer risk due to ionizing radiation exposure with CT. In the setting of complex spine surgery, actions to mitigate this risk should be considered and include reducing nonessential scans, using the lowest possible radiation dose protocols, exerting greater selectivity in monitoring the developing fusion construct, and adopting non-ferromagnetic implant biomaterials that facilitate MRI postoperatively.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1420-9) contains supplementary material, which is available to authorized users.

Carpal bone cysts: MRI, gross pathology, and histology correlation in cadavers

PURPOSE

Intraosseous cysts of carpal bones are frequently observed on routine imaging examinations of the wrist. There is controversy regarding the underlying pathogenesis of these cysts. In this study, we aimed to investigate the magnetic resonance imaging (MRI) appearance of intracarpal bone cysts in correlation with histologic analysis, using cadaveric wrists.

METHODS

Five freshly frozen cadaveric wrist specimens (from three women and two men; mean age at death, 80 years) were studied. Imaging was performed with T1-weighted fast spin-echo, and proton density-weighted fast spin-echo with and without fat-suppression. The existence of cysts was confirmed by comparing MRI and histology findings. Hematoxylin and eosin stain was performed on tissue slices of 3 mm thickness to analyze the structure of cysts and their communication with the joint cavity.

RESULTS

Ten cysts were observed. In all cases, cysts were eccentrically located either in the subchondral bone or beneath the cortex. On histologic examination, there were regions of fat necrosis without inflammation or increased vascularity, surrounded by fibrous walls. There were no giant cells, cholesterol granules, or a true synovial lining. Mucoid change was rare. Fibrous component of cysts varied from small fibrous septa to well-formed walls. Some cysts communicated with the joint cavity. Two cysts were adjacent to ligamentous attachments. Those cysts with fibrous tissue demonstrated variable hypointensity on T2.

CONCLUSION

In contrast to previous reports that described a mucoid composition of intracarpal bone cysts with occasional foamy macrophages, our observations support the concept that these lesions reflect a spectrum of fat necrosis and fibrous changes, without inflammation or hypervascularity. These cysts are typically surrounded by fibrous walls without a true synovial lining.

Extensor retinaculum of the wrist: gross anatomical correlation with MR imaging after ultrasound-guided tenography with emphasis on anatomical features in wrist dorsiflexion responsible for tendon impingement

OBJECTIVE

To demonstrate the anatomy of the extensor retinaculum (ER) of the wrist using gross anatomical correlation with magnetic resonance (MR) imaging before and after ultrasound-guided tenography in four different positions, emphasizing the morphological appearance of the ER that occurs with dorsiflexion of the wrist to define the nature of extensor tendon impingement in athletes who perform repetitive wrist dorsiflexion.

MATERIALS AND METHODS

Institutional policies were followed regarding cadaver use. Ten upper extremities were harvested from fresh cadavers. MR imaging before and after ultrasound-guided tenography of the wrist was performed, followed by gross anatomical correlation. Two radiologists interpreted the MR images and sections by consensus for the anatomical landmarks of the ER, and morphological changes occurring during dorsiflexion of the wrist were analyzed and measured.

RESULTS

The ER of the wrist appeared as a band of low signal intensity on T1- and PD-weighted images. Because of its orientation, axial images were best suited to depict the ER anatomy; specifically, localization of the bony landmarks and the septal attachments. On sagittal images, a consistent appearance of the ER was seen: appearing with fusiform morphology in the neutral position, and becoming shortened and thickened at the abutment point where the extensor tendons of the fourth compartment had a curved excursion during dorsiflexion. The width and thickness of the ER in neutral position averaged 13.56 mm and 1.67 mm respectively. In wrist dorsiflexion, the average width and thickness changed to 8.68 mm and 2.15 mm respectively.

CONCLUSION

Magnetic resonance imaging is a useful technique to demonstrate the ER of the wrist, the septal attachments, and morphological changes that occur during dorsiflexion of the wrist, which potentially can lead to impingement of the extensor tendons.

Frequency of atlantoaxial calcium pyrophosphate dihydrate deposition at CT

PURPOSE

To determine (a) the prevalence of atlantoaxial calcium pyrophosphate dihydrate (CPPD) crystal deposition in a population of patients undergoing computed tomography (CT) for acute trauma and (b) the association between atlantoaxial CPPD crystal deposition and retro-odontoid soft-tissue thickness.

MATERIALS AND METHODS

This HIPAA-compliant study was approved by the institutional review board, and the requirement to obtain informed consent was waived. In 513 consecutive patients, CT scans of the cervical spine obtained for acute trauma were retrospectively reviewed for the presence of atlantoaxial CPPD crystal deposition, and the maximal thickness of the retro-odontoid soft tissues was measured. The relationships among imaging findings, age, and sex were assessed with the t test, the χ(2) test, Spearman correlation, and logistic and linear regression models as appropriate.

RESULTS

The overall prevalence of atlantoaxial CPPD crystal deposition was 12.5% (64 of 513 patients), and prevalence increased with age (P < .0001, logistic regression coefficient). In patients aged 60 years and older, the prevalence of CPPD crystal deposition was 34% (58 of 170 patients). In patients aged 80 years and older, the prevalence of CPPD crystal deposition was 49% (37 of 75 patients). There was a positive correlation between age and retro-odontoid soft-tissue thickness (Spearman ρ = 0.48, P < .0001). The mean retro-odontoid soft-tissue thickness in patients with CPPD crystal deposition was greater than that in patients without CPPD crystal deposition (3.4 mm vs 2.2 mm, respectively; P < .0001, t test).

CONCLUSION

CPPD crystal deposition in the cervical spine is seen with a higher prevalence than previously reported. CPPD crystal deposition shows a positive correlation with age and retro-odontoid soft-tissue thickening.

High origin of the anterior band of the inferior glenohumeral ligament: MR arthrography with anatomic and histologic correlation in cadavers

INTRODUCTION

The anterior band of the inferior glenohumeral ligament has been described to arise from the anteroinferior labrum, but we have observed that in some persons its origin is from the anterior or anterosuperior labrum, creating diagnostic difficulties.

MATERIALS AND METHODS

Ten fresh unembalmed cadaveric shoulders underwent magnetic resonance arthrography (MRA) using a posterior approach with a 1.5 T GE magnet, with the following sequences: T1-weighted fast spin-echo in axial, coronal and sagittal planes, and T1 fat-suppressed spin-echo in the axial plane (TR/TE 600/20, section thickness 2.5 mm, 0.5 mm interslice space, number of signals acquired, two, field of view 12 × 12 cm, and matrix 512 × 256 pixels). Following imaging, the shoulders were frozen and later sectioned using a band saw into 3-mm sections corresponding to the axial imaging plane. Histological analysis was also performed to determine the origin of the anterior band.

RESULTS

Four of the ten shoulders had an origin of the anterior band above or at the 3 o'clock position: one at the 1 o'clock position, two at the 2 o'clock position, and one at the 3 o'clock position. In another shoulder, the anterior band of the inferior glenohumeral ligament originated from the middle glenohumeral ligament, and in five other shoulders, the anterior band originated from the anteroinferior labrum as has been described in the literature.

CONCLUSIONS

This finding is of clinical significance as a high origin of the anterior band of the inferior glenohumeral ligament leads to MR arthrographic finding that can simulate those of labral tears or detachments.

Valid MR imaging predictors of prior knee arthroscopy

PURPOSE

To determine whether fibrosis of the medial patellar reticulum (MPR), lateral patellar reticulum (LPR), deep medial aspect of Hoffa's fat pad (MDH), or deep lateral aspect of Hoffa's fat pad (LDH) is a valid predictor of prior knee arthroscopy.

MATERIALS AND METHODS

Institutional review board approval and waiver of informed consent were obtained for this HIPPA-compliant study. Initially, fibrosis of the MPR, LPR, MDH, or LDH in MR imaging studies of 50 patients with prior knee arthroscopy and 100 patients without was recorded. Subsequently, two additional radiologists, blinded to clinical data, retrospectively and independently recorded the presence of fibrosis of the MPR in 50 patients with prior knee arthroscopy and 50 without. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for detecting the presence of fibrosis in the MPR were calculated. κ statistics were used to analyze inter-observer agreement.

RESULTS

Fibrosis of each of the regions examined during the first portion of the study showed a significant association with prior knee arthroscopy (p < 0.005 for each). A patient with fibrosis of the MPR, LDH, or LPR was 45.5, 9, or 3.7 times more likely, respectively, to have had a prior knee arthroscopy. Logistic regression analysis indicated that fibrosis of the MPR supplanted the diagnostic utility of identifying fibrosis of the LPR, LDH, or MDH, or combinations of these (p ≥ 0.09 for all combinations). In the second portion of the study, fibrosis of the MPR demonstrated a mean sensitivity of 82%, specificity of 72%, PPV of 75%, NPV of 81%, and accuracy of 77% for predicting prior knee arthroscopy.

CONCLUSIONS

Analysis of MR images can be used to determine if a patient has had prior knee arthroscopy by identifying fibrosis of the MPR, LPR, MDH, or LDH. Fibrosis of the MPR was the strongest predictor of prior knee arthroscopy.

High-resolution ultrasound evaluation of the trapeziometacarpal joint with emphasis on the anterior oblique ligament (beak ligament)

INTRODUCTION

The anterior oblique ligament is one of the main stabilizers of the trapeziometacarpal joint. Insufficiency of this ligament is closely linked to degenerative joint disease. High-resolution musculoskeletal ultrasound has advantages over magnetic resonance imaging (availability, dynamic nature, cost, patient comfort). This study evaluates the feasibility of ultrasound of the anterior oblique ligament.

MATERIAL AND METHODS

Ten cadaveric thumb specimens and 10 volunteers with normal trapeziometacarpal joints underwent imaging with high-frequency ultrasound. An ultrasound-guided, progressive dissection technique was used to confirm the ultrasound findings. Two radiologists reviewed the images in consensus. The detectability of the ligament was rated.

RESULTS

The anterior oblique ligament was identified and measured in 90% of the specimens and 100% of the volunteers. The ultrasound findings correlated well with the dissections. This ligament appeared as a thin hypoechogenic structure in the ulnar-most part of the trapeziometacarpal joint, with a thickness that varied from 1.0 to 2.0 mm. Detectability of this ligament was good in 66% of the specimens and 100% of the volunteers.

CONCLUSION

Ultrasound evaluation of the anterior oblique ligament of the trapeziometacarpal joint is feasible with state of the art equipment.

Tibiofibular syndesmotic ligaments: MR arthrography in cadavers with anatomic correlation

PURPOSE

To use magnetic resonance (MR) imaging and MR arthrography to characterize the normal anatomy of the tibiofibular syndesmotic ligaments with standard and oblique imaging planes in cadavers.

MATERIALS AND METHODS

Ten cadaveric ankle specimens were obtained and used in accordance with institutional and HIPAA guidelines, and informed consent for research was obtained from relatives of the deceased. MR imaging was performed before and after intraarticular administration of contrast material. Proton-density-weighted MR images were correlated with anatomic slices.

RESULTS

The anterior inferior tibiofibular ligament (AITFL) had a variable number of bands in all specimens. A separate distal band was identified in all specimens, revealing a more horizontal course than other components of the AITFL and attaching more medially to the anterior margin of the tibial plafond. The posterior inferior tibiofibular ligament (PITFL) and inferior transverse ligament were best seen in coronal oblique planes. The posterior intermalleolar ligament was observed in all specimens and had a variable appearance that ranged from a thin strand to a thick cord. The interosseous ligament (IOL) coursed obliquely to attach proximally to the tibia and insert distally in the fibula. This ligament was fenestrated with separate anterior and posterior fibers. The anterior fibers were more proximal, and the posterior fibers were more distal, attaching to the fibula in close proximity to the PITFL. Coronal images best depicted the course of the IOL.

CONCLUSION

Oblique imaging planes parallel to the long axis of the ligament better display the normal anatomy of the tibiofibular syndesmotic ligaments when compared with standard imaging planes. (c) RSNA, 2010.

Complex distal insertions of the tibialis posterior tendon: detailed anatomic and MR imaging investigation in cadavers

PURPOSE

The purpose of this report was to demonstrate the normal complex insertional anatomy of the tibialis posterior tendon (TPT) in cadavers using magnetic resonance (MR) imaging with anatomic and histologic correlation.

MATERIAL AND METHODS

Ten cadaveric ankles were used according to institutional guidelines. MR T1-weighted spin echo imaging was performed to demonstrate aspects of the complex anatomic distal insertions of the TPT in cadaveric specimens. Findings on MR imaging were correlated with those derived from anatomic and histologic study.

RESULTS

Generally, the TPT revealed a low signal in all MR images, except near the level of the medial malleolus, where the TPT suddenly changed direction and "magic angle" artifact could be observed. In five out of ten specimens (50%), a type I accessory navicular bone was found in the TPT. In all cases with a type I accessory navicular bone, the TPT had an altered signal in this area. Axial and coronal planes on MR imaging were the best in identifying the distal insertions of the TPT. A normal division of the TPT was observed just proximal to the insertion into the navicular bone in five specimens (100%) occurring at a maximum proximal distance from its attachment to the navicular bone of approximately 1.5 to 2 cm. In the other five specimens, in which a type I accessory navicular bone was present, the TPT directly inserted into the accessory bone and a slip less than 1.5 mm in thickness could be observed attaching to the medial aspect of the navicular bone (100%). Anatomic inspection confirmed the sites of the distal insertions of the components of the TPT.

CONCLUSION

MR imaging enabled detailed analysis of the complex distal insertions of the TPT as well as a better understanding of those features of its insertion that can simulate a lesion.

Molecular Imaging: Integration of Molecular Imaging into the Musculoskeletal Imaging Practice

Chronic musculoskeletal diseases such as arthritis, malignancy, and chronic injury and/or inflammation, all of which may produce chronic musculoskeletal pain, often pose challenges for current clinical imaging methods. The ability to distinguish an acute flare from chronic changes in rheumatoid arthritis, to survey early articular cartilage breakdown, to distinguish sarcomatous recurrence from posttherapeutic inflammation, and to directly identify generators of chronic pain are a few examples of current diagnostic limitations. There is hope that a growing field known as molecular imaging will provide solutions to these diagnostic puzzles. These techniques aim to depict, noninvasively, specific abnormal cellular, molecular, and physiologic events associated with these and other diseases. For example, the presence and mobilization of specific cell populations can be monitored with molecular imaging. Cellular metabolism, stress, and apoptosis can also be followed. Furthermore, disease-specific molecules can be targeted, and particular gene-related events can be assayed in living subjects. Relatively recent molecular and cellular imaging protocols confirm important advances in imaging technology, engineering, chemistry, molecular biology, and genetics that have coalesced into a multidisciplinary and multimodality effort. Molecular probes are currently being developed not only for radionuclide-based techniques but also for magnetic resonance (MR) imaging, MR spectroscopy, ultrasonography, and the emerging field of optical imaging. Furthermore, molecular imaging is facilitating the development of molecular therapies and gene therapy, because molecular imaging makes it possible to noninvasively track and monitor targeted molecular therapies. Implementation of molecular imaging procedures will be essential to a clinical imaging practice. With this in mind, the goal of the following discussion is to promote a better understanding of how such procedures may help address specific musculoskeletal issues, both now and in the years ahead.

Arcuate ligament of the wrist: normal MR appearance and its relationship to palmar midcarpal instability: a cadaveric study

OBJECTIVE

To describe the magnetic resonance (MR) imaging and gross anatomic appearance of the scaphocapitate (SC) ligament and triquetrohamocapitate (THC) ligament, which are the radial and ulnar limbs of the composite arcuate ligament, a critical volar midcarpal stabilizing ligament.

DESIGN

T1 spin-echo and 3D gradient-echo MR imaging in the standard, coronal oblique, and axial oblique planes were performed both before and following midcarpal arthrography in seven cadaveric wrists. The seven specimens were then sectioned in selected planes to optimally visualize the SC and THC ligaments. These specimens were analyzed and correlated with their corresponding MR images.

RESULTS

The SC and THC ligaments can be visualized in MR images as structures of low signal intensity that form an inverted "V" joining the proximal and distal carpal rows. The entire ligamentous complex is best visualized with coronal and axial oblique MR imaging but can also be seen in standard imaging planes.

CONCLUSION

SC and THC ligaments together form the arcuate ligament of the wrist. Their function is crucial to the normal functioning of the wrist. Palmar midcarpal instability (PMCI) is a resulting condition when abnormalities of these ligaments occur. Dedicated MR imaging in the coronal and axial imaging planes can be performed in patients suspected of having PCMI.

Pellegrini-Stieda disease: a heterogeneous disorder not synonymous with ossification/calcification of the tibial collateral ligament-anatomic and imaging investigation

OBJECTIVE

Ossification/calcification around the medial femoral condyle has been known as Pellegrini-Stieda (PS) disease for almost 100 years. Little attention has been given to magnetic resonance (MR) imaging characteristics. Our purpose is to demonstrate the anatomy in the medial femoral compartment and imaging findings of PS disease, determining the sites and patterns of ossification.

DESIGN AND PATIENTS

In a cadaveric study seven specimens were dissected to show the anatomic relations of the tibial collateral ligament (TCL) and the tendon of the ischiocondylar part of the adductor magnus muscle, in the medial femoral epicondyle. In order to determine the nature of ossification/calcification in PS disease, MR imaging and radiographic findings in nine patients were analyzed by two observers with attention to the specific site, shape, and orientation of the ossification and its relationship to the tibial collateral ligament (TCL) and adductor magnus tendon. Available clinical history was recorded. A classification system addressing different sites and patterns of ossification was developed.

RESULTS

The anatomic study showed that the TCL and the adductor magnus tendon insert at different sites in the medial femoral condyle and there is no continuation; however, some fibers of the posterior bundle of the TCL overlap the anterior aspect of the adductor magnus tendon. The imaging study showed that shape, orientation, and location of the abnormal calcification and ossification were similar on radiographic and MR imaging analysis. Ossification had an inferior orientation in six cases, a superior orientation in two cases, and both in one case. Four patterns of ossification were noted: (I) a beak-like appearance with an inferior orientation and femoral attachment was present in five cases; (II) a drop-like appearance with an inferior orientation, parallel to the femur, was evident in one case; (III) an elongated appearance with a superior orientation, parallel to the femur, was seen in two cases; and (IV) a beak-like appearance with an inferior and superior orientation, attached to the femur, was seen in one case. The ossification was present in the TCL in six cases, in the adductor magnus tendon in two cases, and in both in one case. The coronal plane was best in detecting and categorizing the ossification.

CONCLUSION

Our data indicate that ossification in PS disease is not confined to the TCL but may also involve the adductor magnus tendon. In some cases, it can be related to the anatomic proximity (overlap) of the fibers of these two structures. PS disease should not be regarded as synonymous with ossification of the TCL. The ossification may be classified into four types. No clinical differences among these types appear to exist.

Arcuate sign of posterolateral knee injuries: anatomic, radiographic, and MR imaging data related to patterns of injury

OBJECTIVE

The "arcuate sign" is considered a pathognomonic sign for injuries of the posterolateral (PL) corner of the knee. The purpose of our study was to identify different patterns of injury to the fibular head that may associate with injuries to specific ligaments and tendons of the PL corner of the knee. The anatomic relations between the insertions of fibular collateral ligament (FCL), biceps femoris tendon (BFT), popliteofibular ligament (PFL), and arcuate ligament in normal cadaveric knees were also investigated.

DESIGN AND PATIENTS

Magnetic resonance imaging was performed in two cadaveric knees which subsequently were dissected. Radiopaque markers were placed upon the fibular insertions of the FCL, BFT, PFL, and arcuate ligament in the dissected knees, and knee radiographs were then obtained. Twelve patients with radiographic or MR imaging evidence of isolated injury to the PL corner of the knee were retrospectively reviewed, with regard to avulsion fractures and marrow edema in the fibular head and the integrity of the ligaments of the PL corner of the knee.

RESULTS AND CONCLUSIONS

The PFL and arcuate ligament were seen to attach directly to the posterior and medial aspect of the styloid process of the fibular head. The FCL and BFT attached as a conjoined structure on the lateral aspect of the fibular head lateral, anterior and inferior to the attachment site of the PFL and arcuate ligament. Injury to the arcuate ligament or PFL was diagnosed in 8 patients who presented with a small avulsion fracture of the styloid process of the fibula (n=2), bone marrow edema in the medial aspect of the fibular head (n=3), or both (n=3). In 4 patients with injury to the conjoined tendon or FCL, a larger avulsion fragment and more diffuse proximal fibular edema were seen. Radiographic and MR imaging findings in injuries of the posterolateral corner of the knee may suggest injury to specific structures inserting in the fibular head.

Complications of anterior cruciate ligament reconstruction: MR imaging

Arthroscopic reconstruction of the anterior cruciate ligament (ACL) using autografts or allografts is being performed with increasing frequency, particularly in young athletes. Although the procedure is generally well tolerated, with good success rates, early and late complications have been documented. As clinical manifestations of graft complications are often non-specific and plain radiographs cannot directly visualize the graft and the adjacent soft tissues, MR imaging has a definite role in the diagnosis of complications after ACL reconstruction and may direct subsequent therapeutic management. Our purpose is to review the normal MR imaging of the ACL graft and present the MR imaging findings of a wide spectrum of complications after ACL reconstruction, such as graft impingement, graft rupture, cystic degeneration of the graft, postoperative infection of the knee, diffuse and localized (i.e., cyclops lesion) arthrofibrosis, and associated donor site abnormalities. Awareness of the MR imaging findings of complications as well as the normal appearances of the normal ACL graft is essential for correct interpretation.

Lesser metatarsophalangeal joints: standard MR imaging, MR arthrography, and MR bursography--initial results in 48 cadaveric joints

PURPOSE

To delineate the normal magnetic resonance (MR) imaging anatomy of the lesser metatarsophalangeal (MTP) joints in a cadaveric model and compare the MR arthrographic and MR bursographic findings with the standard MR imaging findings.

MATERIALS AND METHODS

T1-weighted spin-echo MR imaging of 48 lesser MTP joints of 12 cadaveric feet was performed. The specimens were subsequently evaluated with MR arthrography, MR bursography, or both examinations. Musculoskeletal radiologists evaluated standard MR images to determine the normal appearances of the joint structures, especially the fibrous capsule, plantar plate, and collateral ligament complex (CLC). Signal intensity, morphology, joint thickness, relationships with adjacent structures, and best plane for analysis were analyzed. The contrast material-enhanced (ie, arthrographic and bursographic) MR imaging findings were compared with the standard MR imaging findings.

RESULTS

The coronal plane was best for simultaneous depiction of the fibrous capsule, plantar plate, and collateral ligament complex and for assessment of the relationship between the CLC and the plantar plate. The sagittal plane was best for analysis of the bone attachments of the plantar plate and the transverse plane for evaluation of the CLC attachment sites in the phalanges. MR arthrography enabled identification of the bare areas and recesses of the joints, better delineation of the plantar plate articular surface, and better evaluation of the integrity of the soft-tissue components of the joints. Compared with the other examinations, MR bursography did not help improve these evaluations.

CONCLUSION

MR imaging is an excellent examination for delineating the anatomy of the lesser MTP joints. Compared with standard MR imaging, only MR arthrography helps improve visualization of the fibrous capsule, plantar plate, and CLC of the lesser MTP joints.

Elbow synovial fold syndrome: MR imaging findings

OBJECTIVE

We describe the anatomy and MR imaging appearance of elbow plicae.

MATERIALS AND METHODS

First, five cadavers were evaluated by sectioning and using MR arthrography for evidence of normal or prominent synovial folds to determine the potential origin of elbow plicae. Next, 164 consecutive MR images were evaluated to determine the frequency of the plicae in a clinical population. Last, we retrospectively studied a selected group of eight patients who underwent preoperative MR imaging and in whom enlarged synovial folds were confirmed at surgery.

RESULTS

In the cadavers, the synovial fold appeared to originate from the synovium adjacent to a posterior fat pad. In the clinical population, half the patients showed a synovial fold at the same location; however, most folds were less than or equal to 2 mm in thickness. The eight patients presented clinically with symptoms mimicking an intraarticular body. The synovial fold in symptomatic patients was seen posteriorly just above the olecranon and averaged 3 mm in thickness.

CONCLUSION

A synovial fold extending from the posterior fat pad in the elbow is a frequent finding on MR imaging. In a subgroup of patients, plicae, when thickened, may present clinically as a locking elbow. However, overlap exists between the thicknesses of symptomatic and asymptomatic plicae.

Bicipitoradial bursitis: MR imaging findings in eight patients and anatomic data from contrast material opacification of bursae followed by routine radiography and MR imaging in cadavers

PURPOSE

To use radiography and magnetic resonance (MR) imaging after contrast material opacification of the bursae in cadaveric specimens to demonstrate the anatomy of the bicipitoradial bursa and to report MR imaging findings in patients with bicipitoradial bursitis.

MATERIALS AND METHODS

Bicipitoradial bursa in eight cadaveric elbows were injected with a solution containing gadodiamide, iodinated contrast agent, and gelatin. Radiographs and MR images were obtained in each specimen, with both supination and pronation of the forearm. The morphology and relationships of the bursa were studied. Anatomic sections subsequently were obtained. MR imaging studies in eight patients with bicipitoradial bursitis were also evaluated.

RESULTS

The bicipitoradial bursa revealed a smooth outline and a wide base along the superficial aspect of the radius. The mean volume of contrast material that could be injected before extravasation was 4 mL. The mean size of the bursa was 1.8 x 2.5 cm. The bicipitoradial bursa enveloped the biceps tendon, with internal septation seen in two cases. Displacement of the superficial branch of the radial nerve by the bursa was found in two specimens. Communication between the bicipitoradial bursa and elbow joint was not observed. In patients, MR imaging demonstrated fluid collections in the bicipitoradial bursa in all cases, with compression of branches of the radial nerve in two cases.

CONCLUSION

The anatomy of the bicipitoradial bursa is demonstrated with radiography and MR imaging of bursae. MR imaging allows accurate diagnosis of bicipitoradial bursitis and its effects on adjacent structures.

Extrasynovial spaces of the cruciate ligaments: anatomy, MR imaging, and diagnostic implications

OBJECTIVE

The purpose of our study was to define the anatomy of the extrasynovial space that cruciate ligaments occupy by examining the pattern on MR imaging of normal fluid distribution in the joints around the cruciate ligaments and correlating this distribution with histologic analysis of synovial reflections around the cruciate ligaments.

MATERIALS AND METHODS

MR images of five cadaveric knees were obtained serially after larger and larger amounts of contrast material were injected into the joint space. The patterns of fluid distribution around cruciate ligaments were noted. In two other cadaveric knees, the synovial sheath around the anterior cruciate ligament was injected directly with contrast material under CT guidance. Anatomic and histologic correlation was made with findings on corresponding MR images.

RESULTS

The pattern of fluid distribution is bounded by the synovial reflections around cruciate ligaments. When maximum joint distention is achieved, fluid almost surrounds the cruciate ligaments. The area without fluid is a triangular space between the anterior and posterior cruciate ligaments that appears on the midsagittal image. This triangular space of the cruciate ligaments is an extrasynovial space within which both the anterior cruciate ligament and the posterior cruciate ligament reside.

CONCLUSION

The overlying synovial membrane of the cruciate ligaments does not normally allow joint fluid to enter the substance of the ligaments or the triangular space of the cruciate ligaments. Therefore, fluid collections seen on MR imaging in these extrasynovial spaces or structures likely arises from injury to the cruciate ligaments.

Plantar compartments of the foot: MR appearance in cadavers and diabetic patients

PURPOSE

To demonstrate the plantar compartments of the foot on magnetic resonance (MR) images.

MATERIALS AND METHODS

The plantar compartments of four cadaveric feet underwent MR imaging and were sectioned. Fifteen MR studies in 11 patients with compartmental fluid were evaluated. The epicenter of infection was determined from review of the history, radiographs, and MR images.

RESULTS

In the cadaveric feet, distribution of contrast material conformed to the compartmental anatomic features. MR findings in the specimen correlated exactly with gross findings. All seven feet with infection centered at the second through fourth metatarsal heads demonstrated only central compartment fluid. In seven of eight feet with a more medial or lateral epicenter of infection, fluid was seen in the lateral or medial compartment and in the central compartment. In one foot with a lateral epicenter of infection, fluid was confined to the lateral compartment.

CONCLUSION

MR imaging accurately depicts the compartmental anatomic features of the foot.

Pigmented villonodular synovitis: MRI characteristics

The magnetic resonance imaging (MRI) scans of 26 patients with histopathologically proven pigmented villonodular synovitis (PVNS), involving joints but excluding tendon sheaths, were reviewed retrospectively. The purpose of this study is to define the spectrum and frequency of MRI characteristics for PVNS using conventional spin echo (in two cases before and after intravenous administration of gadopentate dimeglumine) and also gradient echo techniques. A cystic variety is presented, the MRI appearances of which have not been found in a review of the literature.

Painful conditions affecting the first metatarsal sesamoid bones

The sesamoid bones of the first metatarsal exhibit a special anatomic configuration, enveloped by the tendons of the flexor hallucis brevis and lying within the capsule of the first metatarsophalangeal joint. Painful conditions of the hallux sesamoid bones are many and include congenital, traumatic, arthritic, infectious, and ischemic conditions. Because of the complex anatomy and the numerous pain-sensitive structures in the region of the first metatarsophalangeal joint, a differential diagnosis can be challenging. The imaging examination should always begin with conventional radiography, including special axial and lateromedial views of the sesamoid bones. In cases in which results of routine radiography are inconclusive, scintigraphy, conventional or computed tomography, xeroradiography, or magnetic resonance imaging can be used. A thorough understanding of the anatomy; pathophysiology; and clinical, laboratory, and imaging findings is often helpful in the establishment of a diagnosis and management plan for painful conditions of the hallux sesamoid bones.

Osteonecrosis of the knee after arthroscopic surgery: diagnosis with MR imaging

Spontaneous osteonecrosis about the knee typically is a disease of the elderly characterized by an acute onset of pain. The exact cause of this condition has long been debated, although a causative relationship between meniscal tears and spontaneous osteonecrosis about the knee has been postulated. Seven patients with knee pain, meniscal tears, and chondromalacia without initial evidence of osteonecrosis at magnetic resonance (MR) imaging underwent arthroscopic surgery with meniscal recontouring or repair and cartilage shaving. These patients returned within 2-14 months with recurrent pain in the treated knee. MR imaging then demonstrated abnormalities consistent with osteonecrosis. Osteonecrosis of the femoral condyle or tibial plateau may be a late sequela of meniscal injury in association with chondromalacia and arthroscopic surgery. This diagnosis should be suspected in patients with recurrent knee pain after arthroscopic repair of meniscal tears. The precise relationship of this pattern of osteonecrosis to that previously described as spontaneous requires further investigation.

Sonography of thigh abscess: detection, diagnosis, and drainage

Sonographic characteristics and percutaneous catheter drainage of thigh abscesses in 18 patients are described. Most of these patients had underlying diseases including osteomyelitis, trauma, diabetes mellitus, rheumatoid arthritis, leukemia, lymphoma, sepsis, bleeding dyscrasia, and autoimmune disease. Previous procedures on these thigh collections included seven operations and 12 nondiagnostic ward aspirations. All collections were shown by sonography to be either anterior or anterolateral. Two cases referred for drainage were posteromedial; sonography showed these to be mycotic pseudoaneurysms. The abscesses were either anechoic or hypoechoic, and occasionally had debris and septations. Abscesses associated with underlying osteomyelitis abutted the femur; those related to other causes generally were more superficial within muscle or fascial layers. Sonographically guided catheter drainage successfully cured all patients, even those in whom ward aspiration or formal surgery had been unsuccessful. Sonography is a simple and inexpensive method of imaging and guiding the drainage of thigh abscesses. Percutaneous catheter drainage is the treatment of choice in cases in which simple emergency room or ward incision and drainage are inadequate.

Plasma cell dyscrasia with polyneuropathy, organomegaly, endocrinopathy, M protein, and skin changes: the POEMS syndrome. Report on two cases and a review of the literature

Two patients with plasma cell dyscrasias, manifested by osteosclerotic bone lesions and small amounts of M protein, and a complicating multi-system disorder are described. Their features of severe sensory-motor polyneuropathy, organomegaly, endocrine dysfunction, anasarca, elevated CSF protein, and skin hyperpigmentation are similar to a clinical syndrome reported primarily in Japanese men. Two previously unrecognized findings--hyperprolactinemia and an unusual radiographic abnormality of fluffy, spiculated bony proliferation--may facilitate recognition of the syndrome. The relationship of these various manifestations to the plasma cell dyscrasia is unknown, but a number of possibilities are discussed.