Cohort selection

We prospectively enrolled patients with lumbar degenerative disease and instability who needed lumbar fusion from 2013 to 2015 at the Santa Clara Valley Medical Center (SCVMC) in San Jose, CA. SCVMC is a level one trauma center and the county hospital wing of Stanford University Medical Center. IRB approval for the prospective data registry was obtained through SCVMC (approval #15-026ER). Informed patient consent was obtained at the time of treatment. All patients underwent pedicle or cortical screw placement by the senior author. Patients who underwent surgery because of trauma or infection, such as osteomyelitis, were excluded. In total, 18 patients underwent cortical screw fixation, and 15 underwent pedicle screw fixation. Most of the patients in the lumbar pedicle screw fixation group had their spinal fixation surgeries before the institution of lumbar cortical trajectory screws at SCVMC. The only patients who had pedicle screw fixation done after the institution of cortical trajectory screws were the ones with small pedicles (< 7 mm diameter) on preoperative CT scans.

All patients received the same pain regimen postoperatively, with a morphine patient-controlled analgesia pump for 24 hours, followed by long-acting OxyContin and IV morphine and/or Percocet thereafter during the hospital stay. Patients were discharged home on oral Percocet.