Dural damage due to a loosened hydroxyapatite intraspinous spacer after spinous process-splitting laminoplasty. Report of two cases.

Excellent results from laminoplasty for cervical spinal myelopathy have been reported in many studies. Nevertheless, C-5 nerve root palsy or axial pain such as neck and shoulder pain after laminoplasty are known postoperative complications. To the authors' knowledge, dural damage from dislocation of the hydroxyapatite intraspinous spacer due to absorption of the tip of the spinous process has not been reported. Two cases of dural damage from dislocation of the hydroxyapatite intraspinous spacer after laminoplasty are described. Radiographs, computed tomography myelography, and magnetic resonance (MR) imaging revealed the dislocation of the hydroxyapatite intraspinous spacer, the absorption of the tip of the spinous process, and dural sac compression due to the hydroxyapatite intraspinous spacer. In one patient, the MR imaging studies revealed liquorrhea around the hydroxyapatite intraspinous spacers. Both patients underwent removal of the hydroxyapatite intraspinous spacer and attained good neurological recovery. In patients with dislocation of the hydroxyapatite intraspinous spacer associated with absorption of the tip of the spinous process after spinous process-splitting laminoplasty, each case should be evaluated for aggravating symptoms of myelopathy, dural damage, and liquorrhea around the spacer.