The "cello technique" is a new calcaneoplasty technique for the treatment of Haglund disease. It is an ultrasound-assisted technique for resection of the posterosuperior part of the calcaneus. It is possible to resect the posterosuperior part of the calcaneus under direct ultrasound control with the patient in the prone position, with a dorsally positioned ultrasound probe, in line with the Achilles tendon fibers (sagittal line), and with the abrader in the posteromedial working portal. We describe in detail the technique for this new procedure in foot and ankle surgery. This innovative technique offers the possibility of expanding the indications for ultrasound-guided surgery in other fields of orthopaedic surgery.