A subcutaneous fasciotomy is performed to relieve pressure due to compartment syndrome. A small incision is made in a patients skin. A surgical instrument is advanced through the entry location, and moved between the skin and the fascia of the patient to a remote location, with a cutter of the instrument in a stowed configuration. After reaching the remote location, the cutter is deployed to pierce an initial opening in the fascia at the remote location. The fascia is maintained adjacent a blade of the cutter via a notch shape that traps the fascia. The instrument is then withdrawn back toward the entry location with the blade incising the fascia to relieve pressure in the muscle compartment. The surgical instrument is then removed through the entry incision.