Association Between Thenar Musculature and Carpal Tunnel Syndrome.

Background: Dynamic forces acting on the transverse carpal ligament (TCL) may influence the mechanics of the carpal tunnel (CT), thus affecting the occurrence of CT syndrome (CTS). Previous studies demonstrated an association between muscle overlying the CT and the diagnosis of CTS. Understanding the location of insertion/origin of the thenar musculature will allow mechanical analysis of the forces applied to the TCL during performance of individual tasks. Our purpose was to determine the location of muscle overlying the CT on magnetic resonance imaging (MRI) in CTS and controls. Methods: Case-control study of 21 normal adult wrist MRI scans. MRI measurements were performed on an axial cut at the level of the hook-of-hamate. Median nerve cross-sectional area (CSA), median nerve shape and increased signal intensity within the CT were associated with CTS. The amount and length of muscle crossing the midline and the CT on the same cut was measured and the association with the occurrence of CTS was analysed. Results: We found an inverse relationship between the amount of muscle crossing the midline and the size of the CT, and a direct relationship with occurrence of CTS p less than 0.01, but no differences regarding length of muscle crossing the midline. Conclusions: This study supports an association between the thenar musculature location relative to the CT and the predictors of CTS on MRI. Since the location of muscle origin/insertion is variable, their effect may differ accordingly, therefore, further study is needed to describe the exact location of origin/insertion and its differential dynamic or static effect on the pathogenesis of CTS. Level of Evidence: Level IV (Diagnostic).

Deep Learning Diagnosis and Classification of Rotator Cuff Tears on Shoulder MRI.

BACKGROUND: Detection of rotator cuff tears, a common cause of shoulder disability, can be time-consuming and subject to reader variability. Deep learning (DL) has the potential to increase radiologist accuracy and consistency. PURPOSE: The aim of this study was to develop a prototype DL model for detection and classification of rotator cuff tears on shoulder magnetic resonance imaging into no tear, partial-thickness tear, or full-thickness tear. MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act-compliant, institutional review board-approved study included a total of 11,925 noncontrast shoulder magnetic resonance imaging scans from 2 institutions, with 11,405 for development and 520 dedicated for final testing. A DL ensemble algorithm was developed that used 4 series as input from each examination: fluid-sensitive sequences in 3 planes and a sagittal oblique T1-weighted sequence. Radiology reports served as ground truth for training with categories of no tear, partial tear, or full-thickness tear. A multireader study was conducted for the test set ground truth, which was determined by the majority vote of 3 readers per case. The ensemble comprised 4 parallel 3D ResNet50 convolutional neural network architectures trained via transfer learning and then adapted to the targeted domain. The final tear-type prediction was determined as the class with the highest probability, after averaging the class probabilities of the 4 individual models. RESULTS: The AUC overall for supraspinatus, infraspinatus, and subscapularis tendon tears was 0.93, 0.89, and 0.90, respectively. The model performed best for full-thickness supraspinatus, infraspinatus, and subscapularis tears with AUCs of 0.98, 0.99, and 0.95, respectively. Multisequence input demonstrated higher AUCs than single-sequence input for infraspinatus and subscapularis tendon tears, whereas coronal oblique fluid-sensitive and multisequence input showed similar AUCs for supraspinatus tendon tears. Model accuracy for tear types and overall accuracy were similar to that of the clinical readers. CONCLUSIONS: Deep learning diagnosis of rotator cuff tears is feasible with excellent diagnostic performance, particularly for full-thickness tears, with model accuracy similar to subspecialty-trained musculoskeletal radiologists.

The Use of Ultrasound to Differentiate Between Gout and Infection in the Wrist.

BACKGROUND: Gout is a common condition and its prevalence is increasing. In the wrist, acute gouty arthritis is difficult to distinguish from infection and may occur concomitantly. Though aspiration is helpful, it is not always technically feasible or definitive. Imaging may assist in the differential diagnosis. CASE PRESENTATION: Two cases are described in which the use of ultrasound evaluation assisted in the diagnosis and ultimate treatment Conclusion: Ultrasound can be a helpful adjunct in the diagnosis of arthritis of the wrist, helping to tailor treatment in complex cases.

Palmar Musculature: Does It Affect the Development of Carpal Tunnel Syndrome? A Pilot Study.

Background The etiology of carpal tunnel syndrome (CTS) is multifactorial. Static mechanical characteristics of CTS have been described, but dynamic (muscular) parameters remain obscure. We believe that musculature overlying the transverse carpal ligament may have an effect on carpal tunnel pressure and may explain the prevalence of CTS in manual workers. Questions/Purposes To utilize magnetic resonance imaging (MRI) imaging to estimate the amount of muscle crossing the area of the carpal tunnel and to compare these MRI measurements in patients with and without documented CTS. Methods A case-control study of wrist MRI scans between January 1, 2018, and December 1, 2019, was performed. Patients with a diagnosis of CTS were matched by age and gender with controls without a diagnosis of CTS. Axial MRI cuts at the level of the hook of the hamate were used to measure the thenar and hypothenar muscle depth overlying the carpal tunnel. Muscle depth was quantified in millimeters at three points: midcapitate, capitate-hamate border, capitate-trapezoid border. Average depth was calculated by dividing the cross-sectional area (CSA) by the transverse carpal ligament width. Statistical analysis included Student's t -test, chi-square test, and Pearson's correlation coefficient calculation. Results A total of 21 cases and 21 controls met the inclusion criteria for the study. There were no significant differences in demographics between case and control groups. The location and depth of the musculature crossing the carpal tunnel were highly variable in all areas evaluated. A significantly positive correlation was found between proximal median nerve CSA and muscle depth in the capitate-hamate area (correlation coefficient = 0.375; p = 0.014). CSA was not significantly associated with chart documented CTS. Conclusions We found large variability in our measurements. This likely reflects true anatomical variation. The significance of our findings depends on the location of the muscles and the line of pull and their effect on the mechanics of the transverse carpal ligament. Future research will focus on refining measurement methodology and understanding the mechanical effect of the muscular structure and insertions on carpal tunnel pressure. Level of Evidence This is a Level 3, case-control study.

Epidermoid Cyst in an Infected Olecranon Bursa.

Epidermoid cysts are common, benign cysts that form due to follicular epithelium implanting into the dermis. Although these cysts are often painless, they can incite an inflammatory process as well as abscess formation, especially if ruptured. Our case involves a 59-year-old woman with a history of remote elbow trauma diagnosed with septic olecranon bursitis with concomitant epidermoid cyst found on histology following incision and drainage (I&D). Due to the rare presentation and inadequate preoperative imaging, the diagnosis of epidermoid cyst was not made prior to surgery, resulting in incomplete enucleation.

Labral and cartilage abnormalities in young patients with hip pain: accuracy of 3-Tesla indirect MR arthrography.

OBJECTIVE: Assess the diagnostic accuracy of 3-T indirect magnetic resonance arthrography (iMRA) for hip cartilage and labral pathology detection using arthroscopy as the reference standard and compare it to the published performance of direct magnetic resonance arthrography (dMRA). MATERIALS AND METHODS: Between 2009 and 2011, 290 patients suspected of having femoroacetabular impingement underwent iMRA. Our study group consisted of 41 of these patients (17 males, mean age 35 years; 24 females, mean age 33 years) who did not have a prior history of hip surgery and who subsequently underwent arthroscopy. Two experienced musculoskeletal radiologists separately evaluated the randomized and anonymized studies for the presence and quadrant location of labral and cartilage pathology. These recorded data were compared to arthroscopic reports. RESULTS: Forty-one patients had labral pathology, 34 patients had acetabular and 5 patients had femoral cartilage pathology at arthroscopy. Sensitivity, specificity, accuracy, negative- and positive-predictive values for labral lesion detection were respectively 98, 99, 99, 99 and 98 %; for acetabular cartilage lesion detection they were 69, 98, 89, 87 and 95 %; for femoral cartilage lesion detection they were 69, 95, 93 and 39 %. Sensitivities of iMRA by quadrant (anteroinferior, anterosuperior, posteroinferior, posterosuperior) for the labrum were 100.0, 95.0, NA and 85.7 %, for acetabular cartilage were NA, 58.8, NA and 39.5 % and for femoral cartilage were 50.0, 33.3, 75.0 and 75.0 %). NA indicates results not available because of the absence of findings in those quadrants. Specificities of iMRA by quadrant (anteroinferior, anterosuperior, posteroinferior, posterosuperior) for the labrum (95.0, 100.0, 95.1, 67.5 %), acetabular (100.0, 85.7, 92.6, 79.5 %) and femoral cartilage (100.0, 94.7, 96.2, 85.9 %). CONCLUSION: iMRA at 3 T is accurate in detecting labral pathology suggesting that it is a viable alternative to dMRA.

Demystifying radial imaging of the hip.

The hip joint poses unique challenges at magnetic resonance (MR) imaging because of its shape and anatomic position. When conventional imaging planes are used, partial-volume averaging effects may substantially hamper the depiction of cartilage and labral damage at MR imaging. Such effects are most prevalent when the imaging plane is not perpendicular to the curvature of the joint and result in images that poorly depict or fail to depict cartilage and labral conditions. Partial-volume averaging, along with the inherently thin and closely apposed articular cartilage, may be partly to blame for the seemingly disparate reported sensitivities of MR imaging for depicting cartilage damage in the literature, which vary widely depending on whether arthrography was used. Fortunately, the multiplanar capability of MR imaging is not limited to standard anatomic planes. Radial sections, which are obtained perpendicular to the surfaces of the hip joint, provide a true cross section of the cartilage and labrum that conventional planes do not. Radial imaging is a reproducible technique that enhances the morphologic assessment of the articular cartilage and labrum. The additional information it provides is important because early damage occurs in the anterosuperior region of the hip in patients with femoroacetabular impingement.

Anatomic variants and pitfalls of the labrum, glenoid cartilage, and glenohumeral ligaments.

Magnetic resonance (MR) imaging is the primary diagnostic imaging modality for the evaluation of patients with suspected internal derangement of the shoulder joint. Awareness and understanding of the complex anatomy of the shoulder articulation and the ability to recognize normal anatomic variants and potential imaging pitfalls are critical to accurate interpretation of conventional and arthrographic MR imaging studies. This review discusses the normal anatomy and anatomic variants of the glenoid labrum, articular cartilage, and glenohumeral ligaments. An improved understanding of normal anatomy, biomechanics, and variants will help to avoid potential pitfalls in the interpretation of noncontrast and arthrographic shoulder MR imaging examinations.

Gene knockout of glycine transporter 1: characterization of the behavioral phenotype.

N-methyl-d-aspartate receptor (NMDAR) activation requires both the binding of glutamate to its recognition site and occupancy of the strychnine insensitive glycine modulatory site (GMS). Pharmacological studies suggest that the glycine transporter, GlyT1, maintains subsaturating concentrations of glycine at synaptic NMDARs. To characterize further the role of GlyT1, we generated mice in which the gene encoding GlyT1 was inactivated by homologous recombination through insertion of a PGK-Neo cassette in place of exons 2 and 3. Real-time quantitative PCR revealed no transcripts in newborn homozygous [GlyT1(-/-)] mice and a 50% reduction in heterozygous (HZ) [GlyT1(+/-)] mice as compared with WT littermates. The activity of Na(+)-dependent glycine transport in forebrain homogenates was similarly affected. Homozygous mice died within 12 h of birth. In acute hippocampal slices, exogenous glycine or d-serine (10 microM) enhanced NMDAR currents with Schaffer collateral stimulation in WT mice but not HZ mice, suggesting that the GMS was more occupied in the latter. The NMDAR/alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor ratio of the excitatory postsynaptic currents was significantly increased in the HZ mice. In the water maze, the HZ mice exhibited better spatial retention. Furthermore, HZ mice were less sensitive to an amphetamine disruption of prepulse inhibition than WT mice but were more sensitive to the effects of MK-801. Thus, reduced expression of GlyT1 enhances hippocampal NMDAR function and memory retention and protects against an amphetamine disruption of sensory gating, suggesting that drugs which inhibit GlyT1 might have both cognitive enhancing and antipsychotic effects.