Original Investigation Ultrasound-guided Therapeutic Injection and Cryoablation of the Medial Plantar Proper Digital Nerve (Joplin’s Nerve): Sonographic Findings, Technique, and Clinical Outcomes Christopher J. Burke, MBChB, Julien Sanchez, MD, William R. Walter, MD, Luis Beltran, MD, Ronald Adler, MD, PhD Rationale and Objectives: The medial plantar proper digital nerve, also called Joplin’s nerve, arises from the medial plantar nerve, courses along the medial hallux metatarsophalangeal joint, and can be a source of neuropathic pain due to various etiologies, following acute injury including bunion surgery and repetitive microtrauma. We describe our clinical experience with diagnostic ultrasound assess- ment of Joplin’s neuropathy and technique for ultrasound-guided therapeutic intervention including both injection and cryoablation over a 6-year period. Materials and Methods: Retrospective review of all diagnostic studies performed for Joplin’s neuropathy and therapeutic Joplin’s nerve ultrasound-guided injections and cryoablations between 2012 and 2018 was performed. Indications for therapeutic injection and cryoa- blation, were recorded. Studies were assessed for sonographic abnormalities related to the nerve and perineural soft tissues. Post-treat- ment outcomes including immediate pain scores, clinical follow-up, and periprocedural complications were documented. Results: Twenty-four ultrasound-guided procedures were performed, including 15 perineural injections and nine cryoablations. With respect to sonographic abnormalities, nerve thickening (33%) and perineural hypoechoic scar tissue (27%) were the most common find- ings. The mean pain severity score prior to the therapeutic injection was 6.4/10 (range 4À10) and 0.25/10 (range 0À2) following the proce- dure; mean follow-up was 26.2 months (range 3À63 months). All of the cryoablation patients experienced sustained pain relief with a mean length follow-up of 3.75 months (range 0.2À10 months). Conclusion: Therapeutic injection of Joplin’s nerve is a safe and easily performed procedure under ultrasound guidance, with high rates of immediate symptom improvement. For those experiencing a relapse or recurrent symptoms, cryoablation offers an effective secondary potential treatment option. © 2019 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. INTRODUCTION T he medial plantar proper digital nerve (MPPDN), also called Joplin’s nerve, is the medial terminus of the medial plantar nerve, coursing through the sub- cutaneous fat along the medial-plantar aspect of the hallux digit (1,2). Its superficial position makes the nerve susceptible to acute or repetitive trauma, which can produce a neuroma and resultant neuropathy, and may go undiagnosed by practi- tioners unfamiliar with this condition. Joplin's neuroma, first described by Joplin in 1971 (3), describes focal fibrosis of the MPPDN arising from various etiologies, including trauma and biomechanical imbalance Acad Radiol 2019; &:1–10 From the NYU Langone Orthopedic Hospital, Department of Radiology, 301 E 17th St, New York, NY 10003 (C.J.B., J.S., W.R.W., L.B.); NYU Center for Mus- culoskeletal Care, Department of Radiology, Center for Musculoskeletal Care, New York, New York (R.A.). Received February 3, 2019; revised April 24, 2019; accepted May 24, 2019. The study was approved as a retrospective review by the Institutional Review Board. Address correspondence to: C.J.B. e-mail: Christopher.Burke@nyumc.org © 2019 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.acra.2019.05.014 1 ARTICLE IN PRESS