The procedure is done with the patient under general anaesthesia. A probe is inserted laterally through the psoas muscle, under fluoroscopic guidance, to lie alongside the affected disc. A posterior incision is also sometimes made, to allow access for manipulation of the probe. Nerve monitoring is recommended by many specialists. Dilators are inserted around the probe and a retractor is positioned to give the surgeon direct access to the spine. A discectomy is carried out and a cage implant inserted to hold the vertebrae in position. A bone graft (usually from the hip) is inserted between the 2 vertebrae, sometimes with additional support from screws, plates or rods. The procedure may be done at more than 1 level during the same operation. A recent variation of this procedure is oblique lateral interbody fusion, which involves retroperitoneal access anterior to the psoas. It may take a few months before patients are able to return to their normal activities after the procedure.