Reasons for performing study: Diagnosis and treatment of pathologies involving synovial structures in the shoulder region are technically difficult. Ultrasound-guided (UG) injection techniques have been shown to be highly accurate, safe and reliable for various structures in human and equine patients.
Objectives: To develop easy-to-use and reliable UG injection techniques for the infraspinatus bursa (IB), bicipital bursa (BB) and scapulohumeral joint (SHJ) and to compare them with conventional ‘blind’ methods.
Methods: Eight pairs of equine shoulders were positioned on a computed-tomography (CT) table with left and right shoulders randomly assigned to Operator A (UG) and Operator B (‘blind’). Contrast medium mixed with methylene blue was injected into the target structures. Time and number of attempts for correct needle placement and ease of injection were recorded. A CT scan of each shoulder was performed after every injection to evaluate the location of contrast material. Once injections and CT scans were completed, anatomic dissections were conducted. Statistical analysis was used to compare UG and ‘blind’ techniques with significance set at P<0.05.
Results: Intra-synovial injections using UG techniques were successful in all 24 synovial structures compared with 14/24 with conventional methods. The median number and range of needle repositioning to obtain accurate needle placement was 1 (1–2) for UG and 2 (1–4) for the ‘blind’ techniques. The median time and range required for accurate needle placement was 75.5 s (32–210 s) for UG and 43.5 s (11–140) for ‘blind’ technique. In 31% of all attempts, ease of injection was not indicative of successful intra-synovial administration.
Conclusions: Ultrasound-guided injections of IB, BB and SHJ proved to be highly reliable and more accurate than conventional ‘blind’ techniques.
Potential relevance: Ultrasound-guided injection techniques may be of great help for equine practitioners in the diagnosis and treatment of pathologies involving synovial structures in the shoulder region. Further work is needed to confirm these results in clinical cases.