US Patent 6851430 Method and apparatus for endoscopic spinal surgery

A method of performing percutaneous transforaminal endoscopic lumbar surgery on a patient, includes the steps of creating an opening in the patient's skin, passing at least one tubular cannula through the opening so as to create a soft tissue tunnel, placing a semi-tubular spreader over the at least one tubular cannula inside the soft tissue tunnel, placing a flat blade spreader into an opening formed by the semi-tubular spreader, dilating the opening by spreading apart blades of the flat blade spreader, inserting bone grafts through the opening and into an intervertebral space of the patient.