Three-dimensional morphological changes in ossification of the posterior longitudinal ligament of the thoracic spine following posterior decompression and fusion surgery

• Published in: Journal of clinical neuroscience Vol. 127; p. 110764
• Main Authors: Shibuya, Yohei, Katsumi, Keiichi, Watanabe, Kei, Ohashi, Masayuki, Hirano, Toru, Izumi, Tomohiro, Kawashima, Hiroyuki
• Format: Journal Article
• Language: English
• Published: Scotland Elsevier Ltd 01.09.2024
• Subjects: Morphological change; Ossification of the posterior longitudinal ligament; Posterior decompression and fusion; Thoracic spine; Three-dimensional analysis; Morphological change; Ossification of the posterior longitudinal ligament; Posterior decompression and fusion; Thoracic spine; Three-dimensional analysis
• ISSN: 0967-5868; 1532-2653; 1532-2653
• DOI: 10.1016/j.jocn.2024.110764

•Three-dimensional morphological changes of the thoracic OPLL were investigated.•OPLL volume reduction was observed in 41% after PDF surgery.•OPLL thickness had greater reduction in cases with reduced OPLL volume.•Dural pulsation may be involved in OPLL volume reduction. Using three-dimensional image analysis, we previously reported suppression of ossification progression following posterior fusion surgery for cervical ossification of the posterior longitudinal ligament (OPLL). Here, we aimed to evaluate the morphological changes in thoracic OPLL using three-dimensional analysis. Seventeen patients (eight males and nine females; mean age, 56.9 years) who underwent posterior decompression and fusion (PDF) for thoracic OPLL were included. We evaluated the OPLL volume using a novel analysis involving creating a three-dimensional model from computed tomography images to measure the volume accurately. Additionally, OPLL thickness, width, and length were measured on sagittal and axial computed tomography planes. We investigated the morphological changes in OPLL after PDF. Furthermore, patients were classified into reduced volume and increased volume groups and associated factors were compared. The mean OPLL volume was 1,677 mm3 preoperatively and 1,705 mm3 at the final examination and did not significantly differ. Volume reduction was observed in 7 of 17 cases (41 %). Although OPLL width and length significantly increased postoperatively, OPLL thickness significantly reduced from 7.1 mm preoperatively to 6.5 mm postoperatively (all, p < 0.05). The annual thickness changes significantly differed (p <0.05) in the reduced volume group (−0.36 mm/year) compared to that in the increased volume group (−0.06 mm/year). Thoracic OPLL after PDF becomes thinner in the anteroposterior direction but increases horizontally and craniocaudally. The reduction in OPLL thickness was related to a reduction in ossification volume. We believe that volume reduction in thoracic OPLL is influenced by pulsation of the dural sac.