Application of piezosurgery to treat thoracic myelopathy caused by ossification of the ligamentum flavum

Objective: Piezosurgery is based on microvibrations generated by the piezoelectrical effect, which results in selective bone cutting with preservation of adjacent soft tissue. We aimed to study the applicability of piezosurgery in treating thoracic myelopathy caused by ossification of the ligamentum flavum (OLF). Methods: Between June 2011 and October 2015, thoracic myelopathy caused by OLF was diagnosed in 22 patients using plain radiography, CT, and MRI, and diagnoses were confirmed by postoperative pathological examination. Piezosurgery was supportively used to treat thoracic myelopathy in 22 patients with either OLF or dural ossification. After laminectomy, OLF or ossified dural mass was removed by piezosurgery to decompress the spinal canal. The modified Japanese Orthopedic Association (mJOA) scoring system was used to assess neurological status. The degree of postoperative expansion of the spinal cord was calculated on axial CT images. Results: In all 22 cases, Ossified mass, even those adhered onto dura or ossified dura could be safely removed by piezosurgery. No patient experienced any new neurological deficit after surgery. No serious complications ensured, only one patient suffered dura tear. Neurological status improved during follow-up (mean, 22.4 months) from a preoperative mean mJOA score of 5.05 +/- 1.84 to 8.68 +/- 1.52 points (t = 7.14, P < 0.05). Neurological-function recovery rate ranged from 33.3% to 100%. Conclusions: Piezosurgery could be a useful and safe technique for selective bone cutting in OLF decompression and removal, especially DO.