The extensor carpi ulnaris pseudolesion: evaluation with microCT, histology, and MRI

Pediatric Wrist

Pediatric wrist injuries pose unique diagnostic challenges due to distinct bone characteristics in children and their diverse injury patterns. The dynamic development of the wrist, marked by changes in bone age and emerging ossification centers, is crucial to evaluate growth and identify potential pathologies. The skeletal composition, rich in cartilage, renders bones relatively weaker yet more elastic, impacting their susceptibility to fracture. Forearm fractures display diverse patterns influenced by torsional forces. Scaphoid fractures, less common in children, differ from those in adults. Conditions like Madelung's deformity and ulnar variance are more common wrist disorders in the pediatric population. In addition, the scarcity and nonspecificity of symptoms in those with tendon injuries and triangular fibrocartilage complex lesions can be diagnostically challenging. This article reviews pediatric wrist injuries, emphasizing ossification patterns, common fracture types, and developmental variants. Grasping these complexities in pediatric wrist development and associated pathologies is essential for precise diagnosis and treatment.

Extracellular Acetylated Histone 3.3 Induces Inflammation and Lung Tissue Damage

Extracellular histones, part of the protein group known as damage-associated molecular patterns (DAMPs), are released from damaged or dying cells and can instigate cellular toxicity. Within the context of chronic obstructive pulmonary disease (COPD), there is an observed abundance of extracellular histone H3.3, indicating potential pathogenic implications. Notably, histone H3.3 is often found hyperacetylated (AcH3.3) in the lungs of COPD patients. Despite these observations, the specific role of these acetylated histones in inducing pulmonary tissue damage in COPD remains unclear. To investigate AcH3.3's impact on lung tissue, we administered recombinant histones (rH2A, rH3.3, and rAcH3.3) or vehicle solution to mice via intratracheal instillation. After 48 h, we evaluated the lung toxicity damage and found that the rAcH3.3 treated animals exhibited more severe lung tissue damage compared to those treated with non-acetylated H3.3 and controls. The rAcH3.3 instillation resulted in significant histological changes, including alveolar wall rupture, epithelial cell damage, and immune cell infiltration. Micro-CT analysis confirmed macroscopic structural changes. The rAcH3.3 instillation also increased apoptotic activity (cleavage of caspase 3 and 9) and triggered acute systemic inflammatory marker activation (TNF-α, IL-6, MCP-3, or CXCL-1) in plasma, accompanied by leukocytosis and lymphocytosis. Confocal imaging analysis confirmed lymphocytic and monocytic/macrophage lung infiltration in response to H3.3 and AcH3.3 administration. Taken together, our findings implicate extracellular AcH3.3 in inducing cytotoxicity and acute inflammatory responses, suggesting its potential role in promoting COPD-related lung damage progression.

Tendons and Tendon Sheaths of the Hand - An Update on MRI

BACKGROUND

 The tendons of the hand run in close proximity to each other and within retinacular tunnels adjacent to articular joints, while forming intersections in characteristic locations. The enclosing tendon sheaths are often sites of systemic or infectious inflammation.

METHOD

 This review article outlines the different entities of tendon and tendon sheath pathology and their manifestation in the hands. Diagnostic findings in tendon and tendon sheath disorders are illustrated using MRI imaging and discussed in context with the current literature.

RESULTS AND CONCLUSION

 Overuse may cause stenosis in the fibrous outer layer of the retinacula and the A1 annular ligaments as well as tendinosis. In contrast, proliferative tenosynovitis is a disease of the synovial inner layer of the tendon sheath with tendon infiltration and tendinitis. Pyogenic tenosynovitis favors the flexor compartments. Because of the narrow spaces in the hand, a high-resolution MRI technique must be used.

KEY POINTS

  · Diseases of the tendons and tendon sheaths may have a mechanical, degenerative, metabolic, systemic inflammatory, or infectious etiology.. · Fibrous tunnels and bony prominences in close proximity to crossing tendons predispose to mechanical tendon irritation at typical sites of the hand.. · Stenosing tenovaginitis occurs in the fibrous layer of the extensor retinaculum or the A1 annular pulleys. The most frequent manifestations are the "trigger finger" and de Quervain disease.. · Proliferative tenosynovitis affects the synovial layer of the tendon sheaths before infiltrating the tendons. The classic representative is rheumatoid arthritis..

CITATION FORMAT

· Schmitt R, Hesse N, Grunz JP. Tendons and Tendon Sheaths of the Hand - An Update on MRI. Fortschr Röntgenstr 2022; DOI: 10.1055/a-1826-1007.

Subluxation of the extensor carpi ulnaris on magnetic resonance imaging on neutral wrist position: correlation with tenosynovitis of the extensor carpi ulnaris and translation of the distal radioulnar joint

OBJECTIVE

To identify the subluxation degrees of extensor carpi ulnaris (ECU) tendon on neutral wrist MRI in patients with ulnar-sided wrist pain and to evaluate the relationships of ECU subluxation with accompanying imaging findings such as ECU tenosynovitis, distal radioulnar joint (DRUJ) stability, and triangular fibrocartilage complex (TFCC) pathology.

MATERIALS AND METHODS

A total of 297 MRIs of 292 patients having ulnar side pain were reviewed retrospectively. Degrees of ECU subluxation was classified into four grades: grade 0, no subluxation; grade 1, tendon displacement < 50% of the tendon width; grade 2, tendon displacement 51 to 99% of the tendon width; and grade 3, tendon displacement of 100% of the tendon width. ECU tenosynovitis, ECU tendinosis, injuries of triangular fibrocartilage and distal radioulnar ligaments (DRUL), translation ratio of the DRUJ, rotation angle of the DRUJ, and the width, depth, and length of the ulnar groove were assessed on wrist MRI. The relationships between degree of ECU subluxation and these imaging findings were investigated.

RESULTS

Women had higher subluxation degrees of the ECU tendon (p = 0.001). Tenosynovitis of the ECU, sprain of the dorsal DRUL, dorsovolar translation ratio and rotation angle of the DRUJ, and depth and length of the ulnar groove were statistically significantly related to the subluxation degree of the ECU tendon (p = 0.000).

CONCLUSION

High-grade subluxation of the ECU tendon was strongly correlated with ECU tenosynovitis and DRUJ translation. Clinicians and radiologists should scrutinize imaging findings, particularly when patients with ulnar-sided wrist pain have high-grade subluxation of the ECU tendon.

Pulley, Flexor, and Extensor Tendon Injuries of the Hand

Tendon injuries represent the second most common injury of the hand (after fractures) and are a common scanning indication in radiology. Pulley injuries are very frequent in rock climbers with the A2 pulley the most commonly affected. Tendon and pulley injuries can be reliably evaluated using ultrasound (US) and magnetic resonance imaging (MRI). US can be postulated as a first-line imaging modality, allowing dynamic examination. MRI is essential for cases with ongoing diagnostic doubt post-US and also for preoperative pulley reconstruction assessment.

Multimodality Pitfalls of Wrist Imaging With a Focus on Magnetic Resonance Imaging: What the Radiologist Needs to Know

Numerous pitfalls are frequently encountered at multimodality imaging of the wrist, which may mimic various tendinous, osseous, capsuloligamentous, muscular, and neurovascular pathologic conditions. These pitfalls may be secondary to variant anatomy, artifactual due to magnetic resonance imaging or sonographic technique, or represent varying ranges of structure-specific normal including a spectrum of findings associated with aging in asymptomatic subjects. When an imaging finding of questionable significance is encountered, it is critical that the interpreting radiologist make every attempt to review any relevant clinical information in an effort to determine whether the imaging findings in question may account for the patient's presenting symptomology. In order to accurately diagnose true pathology at wrist imaging, it is imperative that the radiologist be familiar with the pitfalls discussed throughout this manuscript that may mimic disease. This familiarity will allow the radiologist to provide a more useful report for referring providers focusing on true pathology while eliminating potentially confusing or misleading findings which are inconsistent with the patient's clinical presentation.

Extensor Carpi Ulnaris Tendon Anatomy May Mimic Tears

Background: Asymptomatic, incidental extensor carpi ulnaris (ECU) tendon abnormalities are frequently noted on imaging studies of the wrist. The aim of this investigation was to determine if variations in gross tendon anatomy existed that could possibly account for these findings on MRI and ultrasound (US) imaging.

Methods: The upper extremities of eleven (6 male and 5 female) formalin preserved cadavers were dissected and examined under loupe magnification with attention to the dorsal-ulnar wrist and hand and the ECU tendon. The tendons were inspected for anatomic variations, degenerative changes, and any other pathologies. The presence of intra-tendinous splits arising within the ECU tendon was noted and measured. The distances of the splits from the distal tendon insertion and the edge of the extensor retinaculum were recorded. Statistical correlations between age and the tendon splits were considered using R-squared to assess a linear regression.

Results: 17 ECU tendons were dissected and examined, and 5 ECU tendons were excluded due to poor preservation of that upper extremity; all five were right sided upper extremities. Eleven of the 17 specimens demonstrated at least one split in the distal tendon: Seven had 1 split, 1 had 2 splits, and 3 had 3 splits. The mean length of the tendon split was 3.52 cm. The mean distance of the distal edge of the split to the tendon insertion site was 2.4 cm. A linear regression was calculated and showed no correlation between age and number of tendon splits.

Conclusions: 64% of specimens showed a longitudinal split in the distal ECU tendon. The location of these frequent splits corresponds to imaging abnormalities on MRI and US in prior studies.

MRI of the Extensor Tendons of the Wrist

OBJECTIVE

This article reviews the normal anatomy of the extensor tendons of the wrist as well as the clinical presentation and MRI appearances of common tendon abnormalities, such as tears, tenosynovitis, intersection syndromes, and associated or predisposing osseous findings. Treatment options are also discussed.

CONCLUSION

We review the anatomy and normal MRI appearance of the clinically important dorsal extensor tendons of the wrist, in addition to the spectrum of abnormalities associated with these tendons.