LAUSR

OBJECTIVE We studied the postoperative morphology of the dura mater and analyzed the probability of epidural hematoma (EH) after anterior controllable antedisplacement and fusion (ACAF). METHODS A total of 63 patients with a diagnosis of ossification of the posterior longitudinal ligament (OPLL) and degenerative kyphosis and stenosis (DKS) had undergone ACAF from 2016 to 2017. All these patients had undergone cervical plain films, computed tomography, and magnetic resonance imaging (MRI). The operation duration, blood loss, and hospital stay were estimated. Radiological assessments included the occupying rate, OPLL type and extent, kyphotic angle, decompression width, and postoperative area of the spinal canal. On sagittal MRI, the postoperative morphology of dura mater was observed. The Japanese Orthopaedic Association scoring system was used to evaluate neurological status. EH and other surgery-related complications were recorded. RESULTS Of the 63 patients, 39 had OPLL and 24 had DKS. All the patients were followed up for 3-18 months (average, 12.5). The mean decompression width and postoperative spinal canal area were 18.7 ± 1.1 mm and 167.7 ± 34.6 mm2 in the OPLL group and 17.9 ± 0.9 mm and 263.1 ± 46.9 mm2 in the DKS group, respectively. On sagittal MRI, the dura mater was classified into 4 types according to its morphology (dune, ladder, wave, and mixed type), protecting the spinal cord as would a suspensory tent. No patient presented with EH. The mean postoperative Japanese Orthopaedic Association score at the last follow-up examination was significantly better than preoperatively. CONCLUSIONS The dura mater can protect the spinal cord like a suspensory tent after ACAF. The occurrence of EH is rare when ACAF is used to treat OPLL and DKS.