BackgroundIsolated gastrocnemius contracture is thought to lead to numerous conditions. Although many techniques have been described for gastrocnemius recession, potential anesthetic, cosmetic, and wound-related complications can lead to patient dissatisfaction. Open and endoscopic recession techniques require epidural anesthesia, lower limb ischemia, and stitches and may lead to damage of the sural nerve, which is not under the complete control of the surgeon at all stages of the procedure.The purpose of this study was to evaluate the safety and efficacy of a new technique based on ultrasound-guided ultra–minimally invasive gastrocnemius recession.MethodsWe performed a pilot study with 22 cadavers to ensure that the technique was effective and safe. In the second phase, we prospectively performed gastrocnemius recession in 23 patients (25 cases) with chronic non-insertional Achilles tendinopathy, equinus foot, and other indications. In the clinical study, we evaluated the range of dorsiflexion before and after the procedure, clinical outcomes with VAS and AOFAS scores, and potential complications, including neurovascular injuries.ResultsWe achieved complete release of the gastrocnemius tendon in all cases in the cadaveric study, with no damage to the sural nerve or vessels and minimal damage to the underlying muscle fibers. Ankle dorsiflexion increased for every patient in the study (mean, 14°; standard deviation, 3°) and was maintained throughout follow-up. The mean preoperative VAS score was 7 (6–9), which improved to 0 (0–1). The AOFAS Ankle-Hindfoot Score improved from a mean of 30 (20–40) to 93 (85–100) at 6 months. No major complications were observed. All patients returned to their previous sports after 6 months.ConclusionsAfter cadaveric and clinical study, we considered the technique to be safe and effective to perform ultrasound-guided ultra–minimally invasive gastrocnemius recession using a 1-mm incision in vivo. This novel technique represents an alternative to open techniques, with encouraging results and with the advantages of reducing pain, obviating lower limb ischemia, deeper anaesthesia, thus decreasing complications and contraindications and accelerating recovery.Electronic supplementary materialThe online version of this article (doi:10.1186/s12891-016-1265-7) contains supplementary material, which is available to authorized users.