Evan Peck, MD, Editor

The first article in the issue addresses fundamental considerations for ultrasound-guided musculoskeletal procedures, including basic ultrasound physics and machine settings; patient, clinician, machine, transducer, and needle positioning; and important safety and technical tips. Six subsequent articles discuss the six major peripheral joint regions commonly encountered in the practice of musculoskeletal ultrasound: shoulder, elbow, wrist and hand, hip, knee, and foot and ankle. For each of these major peripheral body regions, ultrasound-guided aspirations and injections of targets such as joints, bursae, tendon sheaths, and cysts are discussed, including relevant literature and detailed procedural instructions.

Following the discussions of the peripheral joint regions, the focus shifts to the evolving field of ultrasound-guided spine procedures. Although traditionally, most interventional spine procedures have been performed under fluoroscopy, ultrasound possesses unique characteristics that have increased its utilization for spinal procedures, and an article dedicated to that topic is therefore included. Next is an extensive review of ultrasound-guided peripheral nerve procedures. Ultrasound-guided procedures for the diagnosis and treatment of peripheral focal nerve entrapments are discussed in that article, including the suprascapular nerve at the suprascapular notch, deep branch of the radial nerve at the supinator, median nerve at both the pronator teres and the carpal tunnel, lateral cutaneous nerve of the thigh, superficial fibular nerve at the leg, tibial nerve at the ankle, and interdigital neuroma.

The use of orthobiologics in musculoskeletal medical practice has expanded commensurate with the increased use of musculoskeletal ultrasound over the past several years. This exciting and rapidly growing area was deserving of its own article in this issue. The delivery of agents such as platelet-rich plasma and mesenchymal stem cells using ultrasound guidance for the treatment of musculoskeletal disorders is covered extensively in that article. The next article in the issue is dedicated to the evolving and increasingly relevant topic of advanced procedures for tendinopathy, most of which have been developed or increased in safety due to the emergence of ultrasound guidance. As our understanding of the pathophysiology of chronic tendon disease has improved, novel procedures have been developed, including percutaneous needle tenotomy, percutaneous ultrasonic tenotomy, high-volume injection, and percutaneous needle scraping. The evidence for and performance of these procedures are explored in detail in that article. The final article in this issue discusses the interesting origins of the use of ultrasound in medicine, a brief history of musculoskeletal ultrasound, its present state and developments, and its future outlook.

I hope that this issue serves as a concise yet complete review of the most practical and current interventional musculoskeletal ultrasound literature for the practicing clinician. In addition, I believe the reader will find valuable procedural tips and instruction, even for the seasoned musculoskeletal ultrasound interventionalist.