Surgical strategies for thoracic myelopathy due to ossification of ligamentum flavum: A technical note based on radiological type.

Aim: Ossification of the ligamentumflavum (OLF) is a primary cause of thoracic myelopathy. A relatively safe surgical technique based on radiological type is described for the OLF-induced thoracic myelopathy.

Material And Methods: Forty patients with thoracic myelopathy caused by OLF were studied retrospectively. The OLF was divided into fused and non-fused types according to the CT and MRI findings. All patients underwent posterior decompression. For the fused type, open-door laminectomy and for the non-fused type, French-door laminectomy surgical techniques were adopted. Pre-operation, post-operative, and follow-up neurological status were evaluated using the modified Japanese Orthopaedic Association (mJOA) score.

Results: The mean duration of symptoms was 9.2±11.5 and 8.4±9.7months in the non-fused and fused groups, respectively. The apex of OLF at the most severely compressed level was located at 2.7±1.9mm above the disc level: 2.4±1.6 and 3.0±2.2mm in the 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 fused groups, respectively. After the operation, the neurological deficits in all patients improved. With an average follow-up of 33.9 months, the mJOA score ultimately improved in both groups.

Conclusion: In OLF-induced thoracic myelopathy, the en bloc elevation of the laminae with the OLF plaque is emphasized at the key site for surgical decompression. Based on the present classification of OLF, different surgical strategies should be adopted for a safe neurological decompression.