Surgical Strategies for Thoracic Myelopathy due to Ossification of Ligamentum Flavum: A Technical Note Based on Radiological Type

Özet

AIM: Ossification of the ligamentum flavum (OLF) is a primary cause of thoracic myelopathy. A relatively safe surgical techniquebased on radiological type is described for OLF-induced thoracic myelopathy.MATERIAL and METHODS: Forty patients with thoracic myelopathy caused by OLF were studied retrospectively. The OLF wasdivided into fused and non-fused types according to the computed tomography and magnetic resonance imaging findings. Allpatients underwent posterior decompression. For the fused type, open-door laminectomy and for the non-fused type, French-doorlaminectomy surgical techniques were adopted. Preoperative, postoperative, and follow-up neurological conditions were evaluatedusing the modified Japanese Orthopaedic Association (mJOA) score.RESULTS: The mean duration of symptoms was 9.2±11.5 and 8.4±9.7 months in the non-fused and fused groups, respectively. Theapex of OLF at the most severely compressed level was located at 2.7±1.9 mm above the disc level: 2.4±1.6 and 3.0±2.2 mm inthe non-fused and fused groups, respectively. The preoperative mJOA scores were 5.0±1.1 and 4.2±0.9 in the non-fused and fusedgroups, respectively. After the operation, the neurological deficits were improved in all patients. With an average follow-up of 33.9months, the mJOA score was ultimately improved in both groups.CONCLUSION: In OLF-induced thoracic myelopathy, the en-bloc elevation of the laminae with the OLF plaque is emphasized atthe key site for surgical decompression. Based on the present classification of OLF, different surgical strategies should be adoptedfor a safe neurological decompression.