2D-SWE of the Metacarpophalangeal Joint Capsule in Horses

SIMPLE SUMMARY: Osteoarthritis of fore fetlock in horses is a common disorder that causes owners to complain. It leads to changes in periarticular soft tissue composition. Diagnosis is achieved with radiography and ultrasonography when the disorder is already established. Two-dimensional shear wave elastography (2D-SWE) is an ultrasound-based technique that provides information about tissue composition and elasticity, measuring the velocity of shear waves and tissue stiffness. This study aimed to evaluate the feasibility of 2D-SWE of the fore fetlock joint capsule in horses free and affected from osteoarthritis and to compare their elastographic patterns. The technique was reproducible and repeatable. Age and capsule thickness did not seem to influence the elastographic variables in any group. Longitudinal scan, usually preferred by scientists because it produces fewer artifacts, did not provide significant results. Significant differences were found only in transverse scans, with horses with osteoarthritis having less stiff joint capsule. Poor sensitivity and reproducibility were found. Currently, 2D-SWE of the fetlock joint capsule is not suitable for clinical application. The promising results of other studies suggest that future research should be performed to establish a correlation with MRI or synovial fluid markers which are considered gold standard for diagnosis of osteoarthritis. ABSTRACT: (1) Two-dimensional shear wave elastography (2D-SWE) employs an ultrasound impulse to produce transversely oriented shear waves, which travel through the surrounding tissue according to the stiffness of the tissue itself. The study aimed to assess the reliability of 2D-SWE for evaluating the elastosonographic appearance of the distal attachment of the fetlock joint capsule (DJC) in sound horses and in horses with osteoarthritis (OA) (2). According to a thorough evaluation of metacarpophalangeal joint (MCPJ), adult horses were divided in a sound Group (H) and in OA Group (P). Thereafter, a 2D-SWE of MCPJs was performed. Shear wave velocity (m/sec) and Young’s modulus (kPa) were calculated independently by two operators at each selected ROI. Statistical analysis was performed with R software. (3) Results: 2D-SWE had good–excellent inter-CC and intra-CC in both groups. Differences in m/s and kPa between Groups H and P were found in transverse scans with lower values in Group P. No correlation with age or DJC thickness was found. (4) Conclusions: 2D-SWE was repeatable and reproducible. In Group H, DJC was statistically stiffer than in Group P only in transverse scan. The technique showed poor sensitivity and specificity in differentiating fetlocks affected by OA.