TECHNICAL NOTE Ethyl chloride spray for musculoskeletal ultrasound-guided injections: An alternative to subcutaneous injection of local anesthetic solution Amit Shah FRCR | Alessandro Vidoni MD | Sharon McGarry PGD | Mark Davies FRCR | Steven James FRCR | Rajesh Botchu FRCR Department of Musculoskeletal Radiology, Royal Orthopaedic Hospital, Birmingham, B31 2AP, United Kingdom Correspondence Amit Shah, Department of Musculoskeletal Radiology, Royal Orthopaedic Hospital, Birmingham B31 2AP, UK. Email: doctigs@gmail.com Abstract Ultrasound-guided injections such as steroid injections are common procedures involving the mus- culoskeletal system. They are usually performed after a subcutaneous injection of local anesthetic (LA), which can be painful. In 126 consecutive patients, local anesthesia was performed using ethyl chloride spray prior to a therapeutic ultrasound-guided injection in joints, tendons, or bursae. Ninety-nine (78.5%) patients found the use of ethyl chloride spray helpful. The use of ethyl chlo- ride spray is an effective, patient-friendly alternative to the standard injection of local aesthetic for ultrasound-guided therapeutic musculoskeletal injections with the advantage of a lower cost of $0.18 per procedure. KEYWORDS ethyl chloride spray, local anesthetic, musculoskeletal system, ultrasound guided injections 1 | INTRODUCTION Ultrasound (US)-guided therapeutic injections are performed routinely in the musculoskeletal system. Administration of local anesthetic is usually performed prior to performing the definitive therapeutic injec- tion and has been well documented to reduce subsequent pain. 1 Ethyl chloride spray (ECS) is a fast-acting vapo-coolant spray that provides rapid, transient, topical anesthesia. It has been used as an alternative to subcutaneous local anesthetic injection for skin tag excisions, 2 venipuncture/cannulation, Port-a-cath insertion, lumbar punctures, and bone marrow aspirations. 3 ECS is used routinely in pediatric patients to reduce discomfort of injection-associated pain. 4–6 We performed a prospective study to assess the efficacy and patient experience of ECS in US-guided soft tissue and intra-articular injections. 2 | MATERIAL AND METHODS This study was conducted in accordance to local clinical governance guidance and institutional review board approval was obtained. The study included 180 consecutive patients having US-guided injections performed at a tertiary orthopedic hospital. All injections were performed under US guidance and aseptic conditions by a single fel- lowship trained musculoskeletal radiologist. An Acuson S3000 scanner (Siemens Medical Solutions, Malvern, PA) with either a 12 MHz or 14 MHz probe was used. The application of ECS (Axongesic, Ennogen Pharma, UK) was performed by an assistant. The vapo-coolant was sprayed until a thin white film appeared (during approximately 5 s). The therapeutic injection was then performed immediately. After the proce- dure, all patients were given an ECS evaluation form. The cost of the spray per injection was calculated and compared to the cost of stand- ard injection of local anesthetic. 3 | RESULTS One hundred twenty-six patients of 180 responded to the survey with an average of 60 years of age (range, 28–90 years). There was a female predominance. Injected sites included foot joints (n 5 41), trochanteric bursa (n 5 22), ankle joint (n 5 21), Morton’s neuroma (n 5 20), knee joint (n 5 9), extremity tendon (n 5 8), hip joint (n 5 2), acromioclavicu- lar joint (n 5 1), retrocalcaneal bursa (n 5 1), and plantar fascia (n 5 1). Ninety-nine (78.5%) patients reported that ECS was helpful. Thirteen patients (10%) did not comment, 12 (9%) reported no difference com- pared to prior experiences of US-guided injections performed without J Clin Ultrasound. 2018;46:129–131. wileyonlinelibrary.com/journal/jcu V C 2017 Wiley Periodicals, Inc. | 129 Received: 29 March 2017 | Revised: 24 October 2017 | Accepted: 29 October 2017 DOI: 10.1002/jcu.22561