The authors sought to quantify the clinical outcome of microscopic lumbar spinous process–splitting laminectomy in patients with lumbar spinal stenosis (LSS). They performed a microscopic laminectomy in which the spinous process is split longitudinally into 2 halves. For single-level decompression, they inserted a tubular retractor between the split process.
Data obtained in a total of 124 patients were retrospectively analyzed. Patients were divided into 2 groups: the “slip” group, comprising patients with spondylolisthesis-type LSS with vertebral body slippage (Group 1), and the “nonslip” group, comprising patients with spondylosis-type LSS without vertebral body slippage or with LSS due to central protrusion of lumbar disc herniation. Clinical outcome in all patients was evaluated by using the Japanese Orthopaedic Association score. In the slip group, slippage and instability rates were evaluated by using pre- and postoperative dynamic radiographs in the sagittal plane. Postoperative CT images were used to evaluate bony union at 2 sites: a region between the left and right portions of the halved spinous process and a region between the base of the halved process and vertebral arch. Signal intensity of the multifidus muscle at individual decompression levels was evaluated on pre- and postoperative T1- and T2-weighted MR images.
Preoperative clinical symptoms improved significantly after surgery in all patients. Slippage and instability rates in the slip group showed no significant differences when pre- and postoperative conditions were compared. Union rates at the region between the left and right portions of the halved process and the region between the base of the halved process and vertebral arch were 97.1% and 82.5%, respectively. Magnetic resonance imaging showed only a small amount of fat infiltration in the multifidus muscle after surgery in 12.2% of cases.
The authors recommend microscopic lumbar spinous process–splitting laminectomy as a promising minimally invasive surgery for the treatment of LSS.