SSR white paper: guidelines for utilization and performance of direct MR arthrography.

OBJECTIVE: Direct magnetic resonance arthrography (dMRA) is often considered the most accurate imaging modality for the evaluation of intra-articular structures, but utilization and performance vary widely without consensus. The purpose of this white paper is to develop consensus recommendations on behalf of the Society of Skeletal Radiology (SSR) based on published literature and expert opinion. MATERIALS AND METHODS: The Standards and Guidelines Committee of the SSR identified guidelines for utilization and performance of dMRA as an important topic for study and invited all SSR members with expertise and interest to volunteer for the white paper panel. This panel was tasked with determining an outline, reviewing the relevant literature, preparing a written document summarizing the issues and controversies, and providing recommendations. RESULTS: Twelve SSR members with expertise in dMRA formed the ad hoc white paper authorship committee. The published literature on dMRA was reviewed and summarized, focusing on clinical indications, technical considerations, safety, imaging protocols, complications, controversies, and gaps in knowledge. Recommendations for the utilization and performance of dMRA in the shoulder, elbow, wrist, hip, knee, and ankle/foot regions were developed in group consensus. CONCLUSION: Although direct MR arthrography has been previously used for a wide variety of clinical indications, the authorship panel recommends more selective application of this minimally invasive procedure. At present, direct MR arthrography remains an important procedure in the armamentarium of the musculoskeletal radiologist and is especially valuable when conventional MRI is indeterminant or results are discrepant with clinical evaluation.

Accuracy of a Patient-Specific Total Ankle Arthroplasty Instrumentation.

BACKGROUND: Total ankle arthroplasty (TAA) is a preferred surgical option for end-stage ankle osteoarthritis; however, it is a demanding procedure with a higher historical rate of revision compared with ankle fusion. Patient-specific instrumentation (PSI) has been introduced to optimize prosthesis alignment and theoretically overall improve TAA outcomes. The goal of this study is to report on the experience and surgical outcomes of one implant with specific evaluation of the accuracy and reproducibility of the system with respect to prosthesis alignment and prediction of implant size. METHODS: A retrospective, multicentered study involving 4 foot and ankle fellowship-trained orthopaedic surgeon's patients undergoing TAA between January 1, 2015, and December 31, 2018, using the PROPHECY PSI system. RESULTS: 80 TAA procedures were performed. On average the postoperative tibial component alignment was 89.9 (range, 86.1-96.5) degrees in the coronal plane, with a mean sagittal alignment of 88.1 (range, 81.3-96.7) degrees. The mean deviation from neutral sagittal alignment improved from 4.9 ± 3.9 degrees preoperatively to 2.7 ± 1.7 degrees postoperatively, whereas the mean coronal alignment improved from 3.3 ± 2.5 degrees to 1.3 ± 1.1 degrees. The PSI software correctly determined the tibial implant size in 70 patients (89%). Prediction of talar implant sizing was less accurate than the tibial component, with 56 patients (71%) using the predicted sized implant. The overall implant survival at a mean follow-up of 45 months (range, 27-76) was 97.5%. CONCLUSION: We found that this PSI system accurately and reliably assisted in implant total ankle prosthesis positioning within a clinically acceptable margin and without significant outliers. Prediction of implant size was not as accurate as component orientation. LEVEL OF EVIDENCE: Level III, retrospective study.

Distal Radioulnar Joint: Normal Anatomy, Imaging of Common Disorders, and Injury Classification.

The distal radioulnar joint (DRUJ) is the distal articulation between the radius and ulna, acting as a major weight-bearing joint at the wrist and distributing forces across the forearm bones. The articulating surfaces are the radial sigmoid notch and ulnar head, while the ulnar fovea serves as a critical attachment site for multiple capsuloligamentous structures. The DRUJ is an inherently unstable joint, relying heavily on intrinsic and extrinsic soft-tissue stabilizers. The triangular fibrocartilage complex (TFCC) is the chief stabilizer, composed of the central disk, distal radioulnar ligaments, ulnocarpal ligaments, extensor carpi ulnaris tendon subsheath, and ulnomeniscal homologue. TFCC lesions are traditionally classified into traumatic or degenerative on the basis of the Palmer classification. The novel Atzei classification is promising, correlating clinical, radiologic, and arthroscopic findings while providing a therapeutic algorithm. The interosseous membrane and pronator quadratus are extrinsic stabilizers that offer a minor contribution to the joint's stability in conjunction with the joints of the wrist and elbow. Traumatic and overuse or degenerative disorders are the most common causes of DRUJ dysfunction, although inflammatory and developmental abnormalities also occur. Radiography and CT are used to evaluate the integrity of the osseous constituents and joint alignment. US is a useful screening tool for synovitis in the setting of TFCC tears and offers dynamic capabilities for detecting tendon instability. MRI allows simultaneous osseous and soft-tissue evaluation and is not operator dependent. Arthrographic CT or MRI provides a more detailed assessment of the TFCC, which aids in treatment and surgical decision making. The authors review the pertinent anatomy and imaging considerations and illustrate common disorders affecting the DRUJ. Online supplemental material is available for this article. © RSNA, 2022.

Mammary-type myofibroblastoma of the thigh mimicking liposarcoma.

Myofibroblastoma is a rare tumor that was originally described in the breast but has since been found in extra-mammary locations, where it been renamed mammary-type myofibroblastoma (MTM). We describe a case of MTM occurring in the anterior compartment of the thigh, which was initially interpreted as a possible a liposarcoma on MRI. Two subsequent biopsy samples and eventual excision revealed the tumor to have the characteristic pathology of MTM. This benign tumor, albeit rare, needs to be considered in the imaging differential diagnosis of fat containing deep soft tissue masses of the extremity.

Limited added value of whole spine MRI in spondyloarthritis for disease activity assessment.

OBJECTIVE: To evaluate the added value of whole spine magnetic resonance imaging (MRI) for disease activity assessment in ankylosing spondylitis (AS) and psoriatic arthritis (PsA). METHOD: Spine and sacroiliac joint (SIJ) MRI scans requested by rheumatologists between 2012 and 2018 were screened retrospectively, and patients who had known diagnosis of AS or PsA were included, if the MRI was done for disease activity assessment. All MRI scans were reviewed by two experienced musculoskeletal radiologists independently, blinded to patients' diagnosis and to the other MRI. Comparisons were done for the presence of active and structural lesions. In addition, radiologists were asked to rate for "confidence level for active inflammation related to SpA." Analysis was done using the consensus scores. RESULTS: Ninety patients with known diagnosis of AS (n = 55) or PsA (n = 35) were included. The frequency of active and structural lesions was not significantly different both in AS vs PsA, neither in the cervical/thoracic/lumbar spine or the SIJ. The percentage of people only with any inflammatory changes on the spine MRI without any inflammation in the SIJ MRI was 24% in AS and 23% in PsA. However, considering the confidence level of the radiologists on active inflammation, only one patient's spine MRI was scored as active, while SIJ MRI being negative for inflammation. CONCLUSIONS: The spinal MRI had limited added value to the SIJ MRI in SpA, when performed to assess disease activity, limiting its value in routine practice unless clinically indicated. Key Points • Spine MRI adds limited value to SIJs in SpA, when performed for disease activity assessment. • SpA disease activity assessment may be restricted to sacroiliac joint MRI, unless clinically indicated.

The association of patellar tendinosis with patellar maltracking and Hoffa's fat pad impingement: A case-control MRI study.

OBJECTIVES: To assess whether proximal or distal patellar tendinosis is associated with patellar maltracking parameters and superolateral Hoffa's fat pad impingement. METHODS: Institutional radiology database was reviewed for knee MRI scans performed over a 7-year period identifying cases of unequivocal patellar tendinosis, which were separated into 2 groups: proximal and distal tendinosis. For each group of proximal and distal patellar tendinosis, a control group of age and gender matched subjects was assigned. The scans were evaluated for patellar maltracking parameters including patellar alta, tibial tuberosity lateralization, trochlear dysplasia and lateral patellar tilt and for presence of superolateral Hoffa's fat pad edema. These parameters were compared between the case and control groups. RESULTS: Out of 9852 MRI scans, 94 patellar tendinosis cases were included (65 proximal and 29 distal tendinosis) and matched with equal numbers of controls. In the proximal patellar tendinosis group, more subjects had patella alta (22 versus 6, p = 0.0006), lateralization of tibial tuberosity (16 versus 7, p = 0.0495) and superolateral Hoffa's fat pad edema (16 versus 4, p = 0.0073) compared to the control group. In the distal patellar tendinosis group, there was no significant difference in the prevalence of any maltracking indicator or superolateral Hoffa's fat pad edema compared to the control group. CONCLUSION: Proximal patellar tendinosis was associated with patellar maltracking parameters including patella alta, lateralized tibial tuberosity and superolateral Hoffa's fat pad impingement. No association was demonstrated between distal patellar tendinosis and patellar maltracking indicators or superolateral Hoffa's fat pad impingement.

Subperiosteal chondromyxoid fibroma: a rare case involving the humeral diaphysis.

Initially described, in 1948, as a tumor that could be mistaken with chondrosarcoma at histopathology, chondromyxoid fibroma is now a well-recognized entity. Surface-type chondromyxoid fibroma, however, remains an extremely rare occurrence. We present a case of a 55-year-old woman, who experienced right arm pain for 5 years. After unsuccessful treatment for presumed thoracic outlet syndrome, MRI revealed a large mass abutting the anteromedial cortex of the distal humeral diaphysis in a subperiosteal location. Further characterization was made with radiography, CT, and bone scan, which were followed by ultrasound-guided biopsy. Although histopathologic features were suggestive of chondromyxoid fibroma, the diagnosis remained somewhat uncertain initially due to the very unusual location involving the diaphysis of the humerus. Surgical resection was performed, and subsequent histopathologic analysis confirmed the diagnosis of chondromyxoid fibroma. Despite being a rare entity, surface-type chondromyxoid fibroma would need to be considered in the differential when dealing with expansile surface diaphyseal lesions.

Cadaveric Simulation Training Improves Residents' Knowledge and Confidence in Performing Fluoroscopic Guided Joint Injections.

RATIONALE AND OBJECTIVE: Simulation training has been strongly encouraged to enhance radiology trainees' procedural competency. We aimed to assess whether a cadaveric simulation training session was effective in improving radiology residents' subjective technical ability, knowledge and confidence in performing fluoroscopic-guided joint injections. METHODS: As part of the residency program's procedural training curriculum, first year radiology resident participated in a cadaveric, musculoskeletal injection training session including a didactic lecture followed by a practical hands-on component. Trainees performed fluoroscopic guided hip and shoulder injections on fresh cadavers, supervised by two fellowship-trained musculoskeletal radiologists. Trainees' knowledge on indications, contraindications, preprocedural care, complications, and technical ability in performing the procedures, as well as their rating of overall session experience were evaluated with pre- and post-session questionnaires (5 point Likert-scale). The mean residents' scores for pre- and post-session questionnaire items were calculated and compared using paired t-test. The magnitude of difference between mean pre- and post-session scores was compared between the items using analysis of variance. RESULTS: Results Over a 5-year period, 27 trainees participated in the joint injection simulation session. The mean pre- and post-session scores were significantly higher in the post session questionnaire for all five items pertaining to knowledge of indications, contraindications, preprocedural care, complications, and technical ability (all p < 0.0001). The magnitude of improvement was not different between the items (p = 0.45). Most of the participants rated the training facilities, contents, hands-on experience, teaching quality, and session organization as very good or excellent. CONCLUSIONS: Cadaveric joint injection simulation training significantly improved trainees' subjective knowledge, confidence, and technical ability in performing joint injections.

The prevalence and characteristics of osseous erosions associated with parameniscal cysts on knee MRI.

OBJECTIVES: To determine the prevalence and characteristics of erosions associated with parameniscal cysts (PMCs) and to evaluate the profile of the associated meniscal tears MATERIALS AND METHODS: PACS database was reviewed for knee MRI scans performed over a 5-year period identifying those with PMCs in patients aged 18 years and above. The scans with PMCs were evaluated for the presence of associated osseous erosions. These erosions and PMCs were then analyzed. RESULTS: The search revealed 6773 knee MRI examinations, of which 555 had confirmed PMCs. There were 7 PMC-associated erosions for a prevalence of 1.3% (95% CI 0.6, 2.6). All erosions involved the proximal tibia. Three of 7 erosions had underlying marrow edema, and 4 out of 7 had an overhanging margin. The mean dimension of all PMCs was 13 mm (SD = 11). The mean dimension of PMCs associated with erosions was 38 mm (SD = 22), while that of PMCs without erosions was 12 mm (SD = 10) (P < 0.001, Wilcoxon rank sum test). Ninety-three percent (95% CI 90.5, 94.8) of PMCs had associated meniscal tears, most commonly of the horizontal type (57%). All PMCs with underlying erosions were associated with meniscal tears, most commonly complex type tears (5/7). CONCLUSION: Erosions can rarely be associated with contiguous parameniscal cysts (PMCs). These cysts are significantly larger compared with those without underlying erosions.

Accessory anterolateral talar facet: analysis of the morphologic features on MRI.

PURPOSE: To analyze the morphologic features of accessory anterolateral talar facet (AALTF) on MRI that can assist in detecting this entity, identify any associated structural changes and also define its MRI prevalence. METHODS: Two radiologists retrospectively evaluated 140 ankle MRI scans for the presence of AALTF, complimentary anterior calcaneal extension facet and angle of Gissane measurement. One observer evaluated the scans for other structural details including AALTF length, cartilage thickness, bone marrow edema, hind foot coalition and talar beaking. RESULTS: There was a good inter-observer agreement for the detection of AALTF on MRI (Kappa = 0.64). AALTF was present in 33 out of 140 (23.6%) scans. There was no significant difference in the prevalence of AALTF between male and female subjects (P = 0.71). No significant difference in age between those with and those without AALTF (P = 0.96). Angle of Gissane was significantly smaller in ankles with AALTF (P = 0.0367, observer 1 and 0.0003, observer 2). AALTF had a mean length of 7 mm and was covered with cartilage in 25/33 (75.8%) with mean cartilage thickness of 1.4 mm. Complimentary cartilage covered anterior calcaneal facet was demonstrated in 10/33 (30.3%) and had a mean cartilage thickness of 2.5 mm. Talar beaking was more prevalent in ankles with AALTF showing an anterior calcaneal extension facet than those without the latter feature (P = 0.02). CONCLUSION: AALTF is a frequently observed feature on ankle MRI, with good inter-observer reliability for its detection. When present, it is often opposed by a cartilage covered anterior calcaneal extension facet, which can be associated with talar beaking.

Psoriasis is an independent risk factor for entheseal damage in axial spondyloarthritis.

OBJECTIVES: To understand whether psoriasis has disease modifying effects on disease features and/or severity of enthesitis and spine disease in axial SpA (axSpA). METHODS: Patients with a diagnosis axSpA were included. Demographics, patient and physician reported outcomes were collected. Radiographic damage in the spine was assessed using modified Ankylosing Spondylitis Spine Score (mSASSS). Twelve entheses of the upper and lower extremity were assessed using ultrasound, focusing on inflammation and damage separately. The association between mSASSS, enthesitis scores and extra-articular manifestations such as psoriasis was analyzed using linear regression analysis. RESULTS: Among 120 axSpA patients 114 (95%) had axSpA according to The Assessment of SpondyloArthritis international Society (ASAS) criteria. Sixty-two were classified as ankylosing spondylitis (AS), fulfilling the modified New York criteria. Thirty-one patients had psoriasis. For spinal damage, entheseal damage was an independent and the strongest predictor (B = 0.52, p = 0.025), in addition to longer disease duration (B = 0.22, p = 0.045) and male gender (B = 6.1, p = 0.041) but not psoriasis. For enthesitis, psoriasis was found as an independent risk factor to increase the entheseal damage (B = 4.38, p = 0.009), in addition to age (B = 0.17, p = 0.007), male gender (B = 2.8, p = 0.032), mSASSS (B = 0.11, p = 0.035) and body mass index (B = 0.57, p < 0.001), but not entheseal inflammation (B = 2.0, p > 0.05) when corrected for HLA-B27. CONCLUSIONS: Psoriasis is an independent risk factor to increase the severity of entheseal damage, but not spinal damage. Peripheral enthesitis predicts spinal damage, regardless of the subtypes of SpA.

Patellar maltracking: an update on the diagnosis and treatment strategies.

Patellar maltracking occurs as a result of an imbalance in the dynamic relationship between the patella and trochlea. This is often secondary to an underlying structural abnormality. The clinical evaluation can provide useful clues for the presence of such entity; however, the diagnosis can often be challenging especially in the absence of a documented history of patellar dislocation. Imaging, particularly MRI, can detect subtle features that could lead to the diagnosis, probably even more importantly when there is no clear history of patellar dislocation or before its development. This can provide a road map for formulating a treatment strategy that would be primarily aimed at stabilizing the patellofemoral joint to halt or slow the progression of articular cartilage loss. The purpose of this article is to discuss the clinical and radiologic evaluation of patellar maltracking providing an update on the cross-sectional imaging assessment and also a synopsis of the management options.

2018 Frank Stinchfield Award: Spinopelvic Hypermobility Is Associated With an Inferior Outcome After THA: Examining the Effect of Spinal Arthrodesis.

BACKGROUND: Many patients undergo both THA and spinal arthrodesis, and those patients may not fare as well as those who undergo one procedure but not the other. The mechanisms of how spinal arthrodesis affects patient function after THA remain unclear. QUESTIONS/PURPOSES: The aims of our study were to (1) determine how patient-reported outcome measures (PROMs), including the Oxford hip score as well as dislocations and complications compare after THA between patients with and without spinal arthrodesis; (2) characterize sagittal pelvic changes in these patients that occur when moving between different functional positions and test for differences between patients with and without spinal arthrodesis; and (3) assess whether differences in sagittal pelvic dynamics are associated with PROMs, complications, and dislocations after THA. METHODS: In this case-control study, we identified 42 patients (60 hips) who had undergone both THA and spinal arthrodesis between 2002 and 2016 and who were available for followup at a minimum of 12 months (mean, 6 ± 5 years) after the later of the two procedures. These cases were case-control-matched for age, gender, and body mass index with 42 patients (60 hips) who underwent only THA and had no known spinal pathology. All patients completed PROMs, including the Oxford hip score, and underwent four radiographs of the pelvis and spinopelvic complex in three positions (supine, standing, and deep-seated). Cup orientation and various spinopelvic parameters, including pelvic tilt and pelvic-femoral angle, were measured. The difference in pelvic tilt between standing and seated allowed for patient classification based on spinopelvic mobility into normal (± 10°-30°), stiff (< ± 10°) or hypermobile (> ± 30°) groups. RESULTS: Compared with the THA-only group, the THA-spinal arthrodesis group had inferior PROMs (Oxford hip score, 33 ± 10 versus 43 ± 6; p < 0.001) and more surgery-related complications (such as dislocation, loosening, periprosthetic fracture or infection, psoas irritation) (12 versus 3; p = 0.013), especially dislocation (5 versus 0; p = 0.023). We detected no difference in change of pelvic tilt between supine and standing positions between the groups. When standing, patients undergoing THA-spinal arthrodesis had greater pelvic tilt (25° ± 11° versus 17° ± 8°; p < 0.001) and the hip was more extended (193° ± 22° versus 185° ± 30°; p = 0.012). We found that patients undergoing THA-spinal arthrodesis were more likely to have spinopelvic hypermobility (12 of 42 versus three of 42; odds ratio, 5.2; p = 0.02) with anterior tilting of the pelvis. Of all biomechanical parameters, only spinopelvic hypermobility was associated with inferior PROMs (Oxford hip score, 35 ± 9 versus 40 ± 7 in normal mobility; p = 0.049) and was also present in dislocating hips that underwent revision despite acceptable cup orientation. CONCLUSIONS: In patients with spinal arthrodesis who have undergone THA, spinopelvic hypermobility is associated with inferior outcomes, including hip instability. Spinopelvic hypermobility should be routinely assessed because these patients may have a narrow zone of optimum cup orientation that would require new technology to define and assist the surgeon in obtaining it.Level of Evidence Level III, therapeutic study.

Development of RAD-Score: A Tool to Assess the Procedural Competence of Diagnostic Radiology Residents.

OBJECTIVE: The purpose of this study is to develop a tool to assess the procedural competence of radiology trainees, with sources of evidence gathered from five categories to support the construct validity of tool: content, response process, internal structure, relations to other variables, and consequences. SUBJECTS AND METHODS: A pilot form for assessing procedural competence among radiology residents, known as the RAD-Score tool, was developed by evaluating published literature and using a modified Delphi procedure involving a group of local content experts. The pilot version of the tool was tested by seven radiology department faculty members who evaluated procedures performed by 25 residents at one institution between October 2014 and June 2015. Residents were evaluated while performing multiple procedures in both clinical and simulation settings. The main outcome measure was the percentage of residents who were considered ready to perform procedures independently, with testing conducted to determine differences between levels of training. RESULTS: A total of 105 forms (for 52 procedures performed in a clinical setting and 53 procedures performed in a simulation setting) were collected for a variety of procedures (eight vascular or interventional, 42 body, 12 musculoskeletal, 23 chest, and 20 breast procedures). A statistically significant difference was noted in the percentage of trainees who were rated as being ready to perform a procedure independently (in postgraduate year [PGY] 2, 12% of residents; in PGY3, 61%; in PGY4, 85%; and in PGY5, 88%; p < 0.05); this difference persisted in the clinical and simulation settings. User feedback and psychometric analysis were used to create a final version of the form. CONCLUSION: This prospective study describes the successful development of a tool for assessing the procedural competence of radiology trainees with high levels of construct validity in multiple domains. Implementation of the tool in the radiology residency curriculum is planned and can play an instrumental role in the transition to competency-based radiology training.