Whole-body magnetic resonance neurography in patients with chronic inflammatory demyelinating polyneuropathy.

INTRODUCTION/AIMS: Whole-body magnetic resonance neurography (MRN) is an imaging modality that shows peripheral nerve signal change in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). We aimed to explore the diagnostic potential of whole-body MRN and its potential as a monitoring tool after immunotherapy in treatment-naïve CIDP patients. METHODS: Whole-body MRN using coronal 3-dimensional short tau inversion recovery (STIR) sampling perfection with application-optimized contrasts by using different flip angle evolution (SPACE) techniques was performed in patients being investigated for CIDP and in healthy controls. Baseline clinical neuropathy scales and electrophysiologic parameters were collected, and MRN findings were compared before and after CIDP treatment. RESULTS: We found highly concordant symmetrical thickening and increased T2 signal intensities in the brachial/lumbosacral plexus, femoral, or sciatic nerves in five of the eight patients with a final diagnosis of CIDP and none of the healthy controls. There were no treatment-related imaging changes in five patients with CIDP who completed a follow-up study. Diffuse, symmetrical thickening, and increased T2 signal in root, plexus, and peripheral nerves were found in two patients ultimately excluded due to a diagnosis of polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin changes (POEMS) syndrome in addition to signal changes in the muscles, bony lesions, organomegaly, and lymphadenopathy. DISCUSSION: Whole-body MRN imaging shows promise in detecting abnormalities in proximal nerve segments in patients with CIDP. Future studies evaluating the role of MRN in assessing treatment response should consider follow-up scans after treatment durations of more than 4 months.

Radiomics in Musculoskeletal Tumors.

Sarcomas are heterogeneous rare tumors predominantly affecting the musculoskeletal (MSK) system. Due to significant variations in their natural history and variable response to conventional treatments, the discovery of novel diagnostic and prognostic biomarkers to guide therapeutic decision-making is an active and ongoing field of research. As new cellular, molecular, and metabolic biomarkers continue to be discovered, quantitative radiologic imaging is becoming increasingly important in sarcoma management. Radiomics offers the potential for discovering novel imaging diagnostic and predictive biomarkers using standard-of-care medical imaging. In this review, we detail the core concepts of radiomics and the application of radiomics to date in MSK sarcoma research. Also described are specific challenges related to radiomic studies, as well as viewpoints on clinical adoption and future perspectives in the field.

Radiologic evaluation of ankle fracture malunions of the fibula.

Ankle fractures involving the distal fibula are common injuries. Malreductions and subsequent malunions of the distal fibula can result in worse clinical outcomes and posttraumatic arthritis. The ability to accurately evaluate and identify malreductions and malunions of the distal fibula is important. A number of different radiographic and CT measurements have been described to assess fibular length and rotation. This review highlights various radiologic measures and discusses their advantages and limitations.

Imaging in an academic orthopedic shoulder service: a report on incidental lung pathology findings.

INTRODUCTION: Computed tomography (CT) is often utilized for both diagnostic and pre-operative planning purposes in shoulder arthroplasty. Our study reports on the incidence of pulmonary findings in our pre-operative shoulder arthroplasty population over 14 years at our institution. METHODS: We conducted a retrospective review of all "shoulder CT" exams ordered by two orthopedic upper extremity surgeons between the years of 2008 and 2021. These exams were then further analyzed to include only those ordered for the purpose of pre-operative "shoulder arthroplasty" planning. All incidental findings were documented and those with pulmonary findings were then further analyzed. A detailed chart review was then performed on these patients to determine the impact on their planned shoulder arthroplasty. RESULTS: A total of 363 shoulder pre-operative CTs were ordered by our two upper extremity orthopedic surgeons at our institution between the years of 2008 and 2021. Primary lung cancer in the form of adenocarcinoma (n = 3) had an incidence of 0.8% of all CT scans and 1.4% of all pulmonary incidental findings. Fifteen patients (4% of all CT scans and 7% of all pulmonary incidental findings) had no concern for malignancy and were appropriately evaluated with further imaging based on their initial shoulder CT. CONCLUSION: While shoulder arthroplasty and pre-operative planning with CT imaging continue to become more common, so too is the incidence of reported pulmonary findings. From a patient care standpoint, it is important that these findings are accurately identified, appropriately triaged, and communicated clearly to our patients.

Spectrum and patterns of shoulder pathology on MRI in symptomatic elite wheelchair basketball athletes.

BACKGROUND: Wheelchair basketball (WCB) is a popular para-sport adapted for athletes with physical disabilities. Shoulder injuries are commonly reported among WCB athletes. However, the understanding of the specific patterns and characteristics of shoulder injuries in WCB players is currently limited, and there is a lack of comprehensive literature available on this subject. OBJECTIVES: To investigate the spectrum of pathologies observed in elite wheelchair basketball (WCB) athletes referred for MRI evaluation of symptomatic injuries of the shoulder. METHODS: Retrospective review of consecutive elite WCB athletes referred for MRI evaluation of symptomatic shoulder injury. Demographic, clinical, and functional data including international wheelchair basketball federation (IWBF) classification of each athlete were collected. A total of 28 MRI studies were reviewed. Excluding MRI examinations of the same shoulder, 18 study cases were assessed for pathology of the rotator cuff (RC), labrum, long-head of biceps tendon, glenohumeral and acromioclavicular joints, and osseous lesions of the humerus or glenoid. Correlations between clinical-demographic features and MRI findings were statistically evaluated. RESULTS: Supraspinatus tears were observed in 72.2%, infraspinatus tears in 50%, and subscapularis tears in 38.9% shoulders. Articular-sided partial tears frequently involved posterior supraspinatus (88.9%) and anterior infraspinatus (100%). Labral tears were seen in 38.9%, with involvement of the posterosuperior labrum in all tears. Hill-Sachs and osseous Bankart lesions (5.6%), and anterior-inferior labral tears (11.1%), were uncommon findings. Statistically significant correlations were observed of low IWBF point class and non-ambulatory athletes with subscapularis tendinosis (p = 0.015, p = 0.001) and tearing (p = 0.050, p = 0.013), and athletes with limited trunk control with subscapularis tendinosis (p = 0.013). CONCLUSIONS: RC tears are common in elite WCB athletes with pattern of RC and labral tearing suggesting internal (superior-posterior) impingement as a contributory pathoetiologic mechanism. Non-ambulatory, low IWBF point class athletes, as well as those with limited trunk control have a statistically significant increase in subscapularis tendon pathology on MRI.

T2-weighted MRI radiomics in high-grade intramedullary osteosarcoma: predictive accuracy in assessing histologic response to chemotherapy, overall survival, and disease-free survival.

OBJECTIVE: To analyze radiomic features obtained from pre-treatment T2-weighted MRI acquisitions in patients with histologically proven intramedullary high-grade osteosarcomas and assess the accuracy of radiomic modelling as predictive biomarker of tumor necrosis following neoadjuvant chemotherapy (NAC), overall survival (OS), and disease-free survival (DFS). MATERIALS AND METHODS: Pre-treatment MRI exams in 105 consecutive patients who underwent NAC and resection of high-grade intramedullary osteosarcoma were evaluated. Histologic necrosis following NAC, and clinical outcome-survival data was collected for each case. Radiomic features were extracted from segmentations performed by two readers, with poorly reproducible features excluded from further analysis. Cox proportional hazard model and Spearman correlation with multivariable modelling were used for assessing relationships of radiomics features with OS, DFS, and histologic tumor necrosis. RESULTS: Study included 74 males, 31 females (mean 32.5yrs, range 15-77 years). Histologic assessment of tumor necrosis following NAC was available in 104 cases, with good response (≥ 90% necrosis) in 41, and poor response in 63. Fifty-three of 105 patients were alive at follow-up (median 40 months, range: 2-213 months). Median OS was 89 months. Excluding 14 patients with metastases at presentation, median DFS was 19 months. Eleven radiomics features were employed in final radiomics model predicting histologic tumor necrosis (mean AUC 0.708 ± 0.046). Thirteen radiomic features were used in model predicting OS (mean concordance index 0.741 ± 0.011), and 12 features retained in predicting DFS (mean concordance index 0.745 ± 0.010). CONCLUSIONS: T2-weighted MRI radiomic models demonstrate promising results as potential prognostic biomarkers of prospective tumor response to neoadjuvant chemotherapy and prediction of clinical outcomes in conventional osteosarcoma.

The accuracy of routine knee MR imaging in detection of acute neurovascular injury following multiligamentous knee injury.

OBJECTIVE: To assess the accuracy of routine knee MRI in detecting acute popliteal artery and/or common peroneal nerve (CPN) dysfunction following multiligamentous knee injury (MLKI), with correlation of MRI findings to clinical outcome. MATERIALS AND METHODS: Routine MRI knee examinations in 115 MLKI patients (54/115 with acute neurovascular injury, 61/115 without neurovascular injury) were retrospectively reviewed. Cases were classified by injury mechanism and ligamentous injuries sustained. MRI examinations were reviewed by two readers for vascular (arterial flow void, arterial calibre, intimal flap, perivascular hematoma) and CPN (intraneural T2-hyperintensity, calibre, discontinuity, perineural hematoma) injuries. Accuracy of routine knee MRI in the diagnosis of acute neurovascular injury and correlation of MRI findings to clinical outcome were evaluated. RESULTS: Patients included 86/115 males, mean age 33 years. The accuracy of MRI in diagnosis of acute CPN injury was 80.6%, 83.6% (readers 1 and 2): sensitivity (78%, 79.7%), specificity (80%, 86.7%), PPV (78%, 82.5%), and NPV (82.7%, 84.4%). Increased intraneural T2 signal showed a significant correlation to acute CPN dysfunction (p < 0.05). MRI was 75%, 69.8% (readers 1 and 2) accurate in detecting acute vascular injury: sensitivity (73.3%, 86.7%), specificity (75.2%, 67.3%), PPV (30.5%, 36.1%), and NPV (95%, 97.1%). No MRI features of vascular injury showed a statistical correlation with clinical outcome. Neurovascular complications were more common in ultra-low-energy injuries and KD-V3L pattern of ligament disruption. CONCLUSION: Routine MRI is of limited accuracy in assessing vascular complication, but higher accuracy in assessing CPN injury following MLKI. Increased intraneural T2 signal on conventional knee MR imaging shows statistically significant association with clinically documented acute CPN dysfunction following MLKI.

Soft tissue solitary fibrous tumors of the musculoskeletal system: spectrum of MRI appearances and characteristic imaging features.

OBJECTIVE: Solitary fibrous tumors (SFTs) uncommonly occur in the musculoskeletal system, with limited available data on their MRI appearance. This study was performed to assess the MRI features of SFTs in the musculoskeletal system (MSK-SFTs). MATERIALS AND METHODS: Pre-treatment MRI in 39 patients with pathologically proven SFTs in the trunk or extremities was evaluated. Patient demographics, clinical management and follow-up, and lesion histology were reviewed. MRI features including lesion location, size, morphology, signal characteristics, vascularity, and relationship to major neurovascular structures were assessed. RESULTS: MSK-SFTs most frequently occurred in the lower extremity (23/39 cases, 59%), deep to fascia (29/39, 74%), and intermuscular (22/29, 76%) in location. The majority of deep lesions were located along a major neurovascular bundle (20/29, 69%). Lesions had well-defined margins (39/39, 100%), multilobulated contours (27/39, 69%), and measured mean 6.9 ± 2.8 cm. The majority of lesions had slightly hyperintense T1 signal (34/39, 87%) and heterogenous intermediate-to-high T2/STIR signal (28/38, 74%). A "pseudo-cerebriform" internal architectural pattern on fluid-sensitive sequences, with internal lobulations and low signal bands/septations, was observed in 63% (24/38) of lesions. Lesions commonly demonstrated prominent intra-lesional (30/39, 75%) and peripheral juxta-lesional flow voids. Local invasion of surrounding structures was uncommon (3/39, 8%). Mitotically active lesions (p = 0.02) and lesions with tumor necrosis (p < 0.01) were larger in size. Tumor necrosis was associated with T1 heterogeneity (p = 0.04). Distant metastasis occurred in 10% (4/39) of patients, all in mitotically active lesions pre-operatively considered at least at intermediate risk of metastasis. CONCLUSION: MSK-SFTs commonly present as well-defined, hypervascular masses deep to fascia along major neurovascular bundles, with heterogeneous slightly hyperintense T1 signal, intermediate-to-high T2/STIR signal, and prominent macroscopic flow voids.

Gluteus minimus tendon: MR imaging features and patterns of tendon tearing.

PURPOSE: To highlight the spectrum of pathology and patterns of gluteus minimus tendon tearing observed on MR imaging of the hip. METHODS AND MATERIALS: Retrospective review of consecutive hip MRI exams with findings of gluteus minimus tendon (GMin) pathology. A total of 194 exams in 178 patients (148 female, mean age 61) were reviewed. MRI exams are assessed for GMin: tendinopathy, partial, or complete tendon tears. GMin muscular fatty atrophy, enthesopathic cortical irregularities of the greater trochanter (GT), and peri-trochanteric edema or bursal fluid collections were assessed in all cases. In all cases of complete GMin tendon tearing, position and relationship of GMin tendon were assessed relative to its normal insertion site and adjacent soft tissues. RESULTS: Clinical indications for MR imaging included hip pain (n = 151), and weakness or altered gait (n = 13). Insertional GMin tendinopathy was seen in 72, partial tearing in 81, and complete tendon tearing in 40 cases. Complete tendon tearing without proximal retraction was observed in 38/40 cases with soft tissue continuity visualized between distal tendon fibers and the proximal vastus lateralis muscle. Peri-trochanteric bursal fluid (n = 61), osseous irregularities of the GT (n = 118), and fatty atrophy GMin (n = 102) were statistically associated with partial or complete GMin tendon tearing (p < 0.001). CONCLUSIONS: The spectrum of GMin tendon pathology observed on MR imaging ranges from tendinopathy to complete tears. The majority of complete distal GMin tendon tears from the greater trochanter show continuity of distal tendon fibers with the proximal vastus lateralis, distally tethering and limiting proximal tendon retraction.

Imaging features of gluteal in vitro fertilization injection granulomas, with delayed clinical presentation simulating soft tissue sarcoma.

OBJECTIVES: To review the clinical and imaging findings of patients with remote history of intramuscular (IM) in vitro fertilization (IVF) gluteal injections, presenting with signs and symptoms of a possible gluteal soft tissue sarcoma. METHODS AND METHODS: Retrospective review of consecutive patients with a history of prior IVF therapy referred for MRI evaluation of a gluteal soft tissue mass was performed. Six patients were reviewed, with 5 patients meeting study inclusion criteria. Imaging exams (ultrasound n = 3, MRI n = 5) were assessed for lesion location, morphology, and intrinsic imaging characteristics. One case proceeded to percutaneous biopsy with histopathologic correlation. RESULTS: Average patient age was 43 years (range 38-50). Mean time interval between IVF IM injections and MRI was 5.7 years (range 2.2-13 years). Clinical findings included palpable gluteal mass (5/5) and local pain (4/5). Ultrasound showed heterogeneous subcutaneous lesions with varying complex cystic/solid internal echogenicity. On MRI, each case illustrated an irregularly marginated lesion, mean maximal dimension 3.5 cm (range 1.5-5.9 cm), within the deep gluteal subcutaneous fat composed of solitary (1/5) or multifocal (4/5) lobules demonstrating internal areas of high T1 and homogeneous low T2 fat suppressed signal with surrounding peripheral reticular high T2 signal. Correlative histological assessment showed central areas with features of fat necrosis and a peripheral inflammatory rim. CONCLUSIONS: In the setting of prior IVF therapy, imaging features of an irregularly marginated, deep subcutaneous gluteal lesion with inflammatory soft tissue changes surrounding solitary or multifocal areas of loculated fat signal may be seen as an inflammatory response to previous inadvertent subcutaneous injection(s).

Preoperative Magnetic Resonance Imaging Accurately Detects the Arthroscopic Comma Sign in Subscapularis Tears.

PURPOSE: To assess the accuracy and reliability of routine preoperative magnetic resonance imaging (MRI) in the detection of the comma sign compared with the gold standard of arthroscopic findings. METHODS AND MATERIALS: Preoperative MRI exams in consecutive patients undergoing arthroscopic subscapularis tendon repair, over a 5-year time frame, were retrospectively reviewed for full-thickness tears of the subscapularis and supraspinatus tendons, fatty atrophy of the subscapularis and supraspinatus muscles, and status of the long head of the biceps tendon. Each case was also evaluated for presence or absence of a comma sign on MRI. Surgical findings served as the diagnostic standard of reference in determination of a comma sign. RESULTS: The study cohort included 45 male and 10 female patients (mean age, 56; range, 32-80 years). A comma sign was present at arthroscopy in 19 patients (34.5%). Interclass and intrarater correlation showed 100% agreement in preoperative assessment of a comma sign on MRI. MRI showed an overall accuracy of 83.6% in diagnosis of a comma sign (sensitivity, 63.2%; specificity, 94.4%; positive predictive value, 85.7%; negative predictive value, 82.9%; positive likelihood ratio, 11.37; negative likelihood ratio, 0.39). No statistically significant association was observed between an arthroscopic comma sign and patient demographics or MRI findings of full-thickness rotator cuff tears, muscle fatty atrophy, or long head of the biceps tendon pathology. CONCLUSIONS: MR imaging illustrates excellent reliability and good specificity and accuracy in detection of the arthroscopic comma sign in the setting of subscapularis tendon tearing. Detection of a comma sign on MRI may be important preoperative planning information in the arthroscopic management of patients with subscapularis tendon tears. LEVEL OF EVIDENCE: Level IV, retrospective diagnostic study.

Core curriculum online lecture series in musculoskeletal imaging: initial results.

OBJECTIVE: To augment the educational resources available to training programs and trainees in musculoskeletal (MSK) radiology by creating a comprehensive series of Web-based open-access core curriculum lectures. MATERIALS AND METHODS: Speakers with recognized content and lecturing expertise in MSK radiology were invited to create digitally recorded lecture presentations across a series of 42 core curriculum topics in MSK imaging. Resultant presentation recordings, organized under curriculum subject headings, were archived as open-access video file recordings for online viewing on a dedicated Web page (http://radiologycorelectures.org/msk/). Information regarding the online core curriculum lecture series was distributed to members of the International Skeletal Society, Society of Skeletal Radiology, Society of Chairs of Academic Radiology Departments, and the Association of Program Directors in Radiology. Web page and online lecture utilization data were collected using Google Analytics (Alphabet, Mountain View, CA, USA). RESULTS: Forty-two lectures, by 38 speakers, were recorded, edited and hosted online. Lectures spanned ACGME curriculum categories of musculoskeletal trauma, arthritis, metabolic diseases, marrow, infection, tumors, imaging of internal derangement of joints, congenital disorders, and orthopedic imaging. Online access to the core curriculum lectures was opened on March 4, 2018. As of January 20, 2019, the core curriculum lectures have had 77,573 page views from 34,977 sessions. CONCLUSIONS: To date, the MSK core curriculum lecture series lectures have been widely accessed and viewed. It is envisioned that the initial success of the project will serve to promote ongoing content renewal and expansion to the lecture materials over time.

Advanced Imaging Techniques in the Knee: Benefits and Limitations of New Rapid Acquisition Strategies for Routine Knee MRI.

OBJECTIVE: The purpose of this article is to review current and emerging techniques and strategies that can be used to accelerate acquisition times in routine knee MRI. CONCLUSION: Specific techniques reviewed include 3D fast spin-echo imaging as well as new approaches to rapid image acquisition techniques (parallel imaging, compressed sensing, simultaneous multislice, and neural network reconstruction techniques) and their potential application to knee MRI.

Accuracy of non-arthrographic 3T MR imaging in evaluation of intra-articular pathology of the hip in femoroacetabular impingement.

OBJECTIVE: To investigate the accuracy of non-arthrographic 3-T MRI compared to hip arthroscopy in the assessment of labral and cartilaginous pathology in patients with suspected FAI. MATERIALS AND METHODS: Following IRB approval and waived consent, 42 consecutive cases of suspected FAI with non-arthrographic 3-T MRI and arthroscopy of the hip were reviewed. High-resolution TSE MR imaging was evaluated in consensus by two musculoskeletal radiologists, blinded to arthroscopic findings, for the presence of labral tears and articular cartilage lesions. Acetabular cartilage was categorized as normal, degeneration/fissuring, delamination, or denudation. MRI findings were compared to arthroscopy. Sensitivity, specificity, accuracy, and predictive values for MRI were calculated using arthroscopy as the standard of reference. RESULTS: Forty-two hips in 38 patients with a mean age of 29 (range 13-45 years) were assessed. Mean interval between MRI and arthroscopy was 154 days (range 27-472 days). MRI depicted 41 cases with labral tears (sensitivity 100%, specificity 50%, accuracy 98%, PPV 98%, NPV 100%), 11 cases with femoral cartilage abnormalities (sensitivity 85%, specificity 100%, accuracy 95%, PPV 100%, NPV 94%), and 36 cases with acetabular cartilage lesions (sensitivity 94% specificity 67%, accuracy 90%, PPV 94%, NPV 67%). Of the 36 cases with acetabular cartilage lesions on MRI, 7 were characterized as degeneration/fissuring, 26 as delamination, and 3 as denudation, with discordant results between MRI and arthroscopy for grading of articular cartilage in ten cases. CONCLUSION: Non-arthrographic 3-T MR imaging is a highly accurate technique for evaluation of the labrum and cartilage in patients with clinically suspected FAI.

Imaging of Athletic Injuries of Knee Ligaments and Menisci: Sports Imaging Series.

Acute knee injuries are a common source of morbidity in athletes and if overlooked may result in chronic functional impairment. Magnetic resonance (MR) imaging of the knee has become the most commonly performed musculoskeletal MR examination and is an indispensable tool in the appropriate management of the injured athlete. Meniscal and ligamentous tearing are the most frequent indications for surgical intervention in sports injuries and an understanding of the anatomy, biomechanics, mechanisms of injury, and patterns of injury are all critical to accurate diagnosis and appropriate management. These will be discussed in reference to meniscal tears and injuries of the cruciate ligaments as well as injuries of the posterolateral and posteromedial corners of the knee. (©) RSNA, 2016.

MRI findings of serous atrophy of bone marrow and associated complications.

OBJECTIVES: To report the MRI appearance of serous atrophy of bone marrow (SABM) and analyse clinical findings and complications of SABM. METHODS: A retrospective search of MRI examinations of SABM was performed. Symptoms, underlying conditions, MRI findings, delay in diagnosis and associated complications were recorded. RESULTS: We identified 30 patients (15 male, 15 female; mean age: 46 ± 21 years) with MRI findings of SABM. Underlying conditions included anorexia nervosa (n = 10), cachexia from malignant (n = 5) and non-malignant (n = 7) causes, massive weight loss after bariatric surgery (n = 1), biliary atresia (n = 1), AIDS (n = 3), endocrine disorders (n = 2) and scurvy (n = 1). MRI showed mildly hypointense signal on T1- weighted and hyperintense signal on fat-suppressed fluid-sensitive images of affected bone marrow in all cases and similar signal abnormalities of the adjacent subcutaneous fat in 29/30 cases. Seven patients underwent repeat MRI due to initial misinterpretation of bone marrow signal as technical error. Superimposed fractures of the hips and lower extremities were common (n = 14). CONCLUSIONS: SABM occurs most commonly in anorexia nervosa and cachexia. MRI findings of SABM are often misinterpreted as technical error requiring unnecessary repeat imaging. SABM is frequently associated with fractures of the lower extremities. KEY POINTS: • SABM occurs in several underlying conditions, most commonly anorexia nervosa and cachexia. • Abnormal marrow signal is often misinterpreted as technical error requiring unnecessary repeat imaging. • SABM is frequently associated with stress fractures. • Fractures in SABM can be obscured by marrow signal abnormality on MRI.

MRI of Labral and Chondral Lesions of the Hip.

OBJECTIVE: Unenhanced MRI, indirect MR arthrography, and direct MR arthrography have been used in the radiologic evaluation of patients with suspected labral tears and chondral lesions of the hip. The purpose of this article is to examine the existing evidence for the use of these techniques in patients with hip pain and suspected labral or chondral abnormalities. CONCLUSION: Evidence from a review of the radiologic literature supports the use of direct MR arthrography over unenhanced MRI and indirect MR arthrography for the detection of labral and cartilage abnormalities in the hip. Although high-resolution unenhanced 3-T MRI appears promising, limited information in the literature supports its use in the detection and characterization of chondrolabral lesions.

Trans-subscapularis portal versus low-anterior portal for low anchor placement on the inferior glenoid fossa: a cadaveric shoulder study with computed tomographic analysis.

PURPOSE: The purpose of this study was to evaluate the accuracy of inserting a glenoid anchor at the 5:30 clockface position using a trans-subscapularis (TSS) portal versus a low anterior (LA) portal. METHODS: Five surgeons (T.D., J.C., C.V., D.J.O-H., J.S.T.) placed a single anchor in 20 fresh-frozen cadaveric shoulders. In each of 2 shoulders, surgeons used an LA portal to insert the anchor, whereas in 2 shoulders a TSS portal was used. Surgeons were directed to place the anchor at the 5:30 position at an angle 45° to the glenoid surface (axial plane) and passing perpendicular to the glenoid rim in the coronal plane. Shoulders were then dissected and computed tomographic (CT) scans obtained. Anchor position relative to the clockface was documented by 2 blinded assessors, as was the angle of insertion in the axial and coronal planes. Statistical significance was calculated with a Student t test for paired samples (confidence interval [CI], 95%; significance, P < .05). RESULTS: The average deviation from the 5:30 position was 48 minutes (standard deviation [SD], 31 minutes) for the LA portal (average position, 4:42 o'clock) versus 28.5 minutes (SD, 19 minutes) for the TSS group (average position, 5:02 o'clock) (P = .15). The average angle of anchor insertion in the axial plane was 67.2° (SD, 19°) for the LA portal versus 62.8° (SD, 14°) for the TSS portal (P = .49), whereas the average angle of insertion in the coronal plane was 31.3° (SD, 14°) of inferior angulation in the LA group and 14.3° (SD, 8°) of inferior angulation in the TSS group (P = .009). Of the anchors inserted, 9 of 20 (45%) showed evidence of far-cortical perforation. No difference in cortical perforation was seen between the 2 portals, with perforation more likely with anchors inserted greater than 45° in the axial plane (8 of 20) than with those inserted less than 45° (1 of 20) (P = .02). CONCLUSIONS: The use of a TSS portal improves the angle of approach to the inferior glenoid rim in comparison with an LA portal, reducing the acuity of the angle of insertion in the coronal plane. CLINICAL RELEVANCE: The TSS portal is an option for surgeons performing arthroscopic Bankart repair using anchors low on the glenoid rim.

Pitfalls and pearls in MRI of the knee.

OBJECTIVE: The purpose of this article is to review the common pitfalls in MRI of the knee and pearls on how to avoid them. CONCLUSION: MRI of the knee is highly accurate in evaluation of internal derangements of the knee. However, a variety of potential pitfalls in interpretation of abnormalities related to the knee have been identified, particularly in evaluation of the menisci, ligaments, and articular cartilage.