Ultrasound-guided arthrocentesis and intra-articular injections of the elbow and stifle joint in the dog

Abstract Objective To provide a video tutorial on ultrasound-guided arthrocentesis and injection of the canine elbow and stifle joints. Animals Dogs undergoing arthrocentesis or IA injections for diagnostic or therapeutic purposes. Methods The target joint is visualized in long axis with a 70% isopropyl alcohol medium and linear array probe with a frequency range of 2 to 14 MHz and a footprint of 50 mm after clipping a window and preparing the region sterilely. The needle is inserted, bevel up, in long axis with probe and angled at the appropriate trajectory to enter the visible joint space. The needle is advanced until the tip is visualized entering the joint. Aspiration to obtain synovial fluid can further confirm needle placement or provide diagnostic sampling prior to injection. The aspirate syringe is exchanged for that containing the therapeutic agent, and then injectate can be visualized entering and/or expanding the joint upon injection. Results Ultrasound-guided arthrocentesis will help avoid surrounding vasculature and soft tissue structures of concern, confirm needle placement, and target fluid pocketing. Needle guidance into a joint can reduce iatrogenic tissue damage from inappropriate needle placement and/or by minimizing attempts. Clinical Relevance For arthrocentesis, ultrasound guidance can maximize joint fluid volume acquisition for diagnostic purposes (cytology, culture, and fluid analysis) while also avoiding blood contamination. For joint injections, ultrasound will help ensure IA delivery of the injectate to maximize its effects, particularly when synovial fluid aspirate feedback is inhibited by joint pathology (dry joint or obstructive synovial proliferation). Imaging guidance will help avoid iatrogenic tissue damage and reduce procedure time.