Surgical results and prognostic factors following percutaneous full endoscopic posterior decompression for thoracic myelopathy caused by ossification of the ligamentum flavum

Abstract

Minimally invasive surgery (MIS) has shown satisfactory surgical results for the treatment of thoracic myelopathy (TM) caused by ossification of the ligamentum flavum (OLF). This study investigated the prognostic factors following MIS and was based on the retrospective analysis of OLF patients who underwent percutaneous full endoscopic posterior decompression (PEPD). Thirty single-segment OLF patients with an average age of 60.4 years were treated with PEPD under local anaesthesia. Clinical data were collected from the medical and operative records. The surgical results were assessed by the recovery rate (RR) calculated from the modified Japanese Orthopaedic Association (mJOA) score. Correlations between the RR and various factors were analysed. Patients' neurological status improved from a preoperative mJOA score of 6.0 ± 1.3 to a postoperative mJOA score of 8.5 ± 2.0 (P < 0.001) at an average follow-up of 21.3 months. The average RR was 53.8%. Dural tears in two patients (6.7%, 2/30) were the only observed complications. Multiple linear regression analysis showed that a longer duration of preoperative symptoms and the presence of a high intramedullary signal on T2-weighted MRI (T2HIS) were significantly associated with poor surgical results. PEPD is feasible for the treatment of TM patients with a particular type of OLF. Patients without T2HIS could achieve a good recovery if they received PEPD early. Thoracic myelopathy (TM) is less common than cervical myelopathy and lumbar spinal stenosis 1 , and TM is mainly caused by ossification of the ligamentum flavum (OLF) in East Asian countries, such as Japan, Korea, and China 2. As the number of reported cases has increased, OLF has been studied not only in East Asia but also worldwide 3-5. Although much of its pathophysiology has been determined, the exact pathogenetic mechanism and the epidemiology of OLF remain poorly understood 6,7. Therefore, making an appropriate and timely therapeutic decision for the treatment of OLF may be hindered by the paucity of knowledge. TM caused by OLF remains a challenge for spine surgeons. OLF generally requires posterior surgical decompression due to its progressive nature and poor response to conservative therapy 8,9. Decompression procedures include traditional open surgeries, such as laminectomy with or without posterior fusion 10,11 , and minimally invasive surgery (MIS), such as microendoscopic decompression 12,13 and percutaneous endoscopic decompression 14-17. However, the prognostic guidelines are still unclear, and the surgical results vary widely despite complete decompression 3,18 .

Full endoscopic surgery for thoracic pathology: an assessment of supportive evidence

“…Interlaminar surgery was mainly limited to patients with stenosis and ossification of the ligamentum flavum replicating the results from open surgery. 24 , 61 Calcification of the disc may also present unique problems and require the availability of specialist endoscopic instruments. 49 …”

“…The incision is about 3 cm from the midline unless contralateral decompression is needed, in which case 5 cm may be more appropriate. 24 After stepwise dilatation the endoscope is inserted. The laminae and interlaminar window are decompressed with a combination of a diamond burr and Kerrison punches.…”

Design of a robot-assisted system for transforaminal percutaneous endoscopic lumbar surgeries: study protocol

“…In recent years, with the development of endoscopic surgical equipment and technology, minimally invasive spinal surgeries can be performed with various endoscopic techniques for the lumbar, cervical, and thoracic regions [23][24][25]. There has been a growing body of literature that not only confirms the efficacy of the endoscopic technique but also underscores the advantages with respect to less morbidity and safer complications [3,4,[26][27][28][29][30]. Percutaneous endoscopic spinal surgeries for lumbar, cervical, and thoracic regions categorized according to the surgical approaches are as follows: transforaminal lumbar, interlaminar lumbar, anterior cervical, posterior cervical, posterior thoracic, and posterolateral thoracic [23,31].…”

Design of a robot-assisted system for transforaminal percutaneous endoscopic lumbar surgeries: study protocol

“…In recent years, with the development of endoscopic surgical equipment and technology, minimally invasive spinal surgeries can be performed with various endoscopic techniques for the lumbar, cervical, and thoracic regions [22][23][24]. There has been a growing body of literature that not only con rms the e cacy of the endoscopic technique but also underscores the advantages with respect to less morbidity and safer complications [3,4,[25][26][27][28][29]. Percutaneous endoscopic spinal surgeries for lumbar, cervical, and thoracic regions categorized according to the surgical approaches are as follows: transforaminal lumbar, interlaminar lumbar, anterior cervical, posterior cervical, posterior thoracic, and posterolateral thoracic [21,30].…”