PurposeThe objective of this study was to clarify the characteristics of immediate neurological deterioration (ND) after ambulation and its potential preventative measures using multi-rod reinforcement during posterior decompression and fusion (PDF) with instrumentation for thoracic ossification of the posterior longitudinal ligament (T-OPLL).MethodsStudy 1: Fifteen patients with T-OPLL who underwent PDF before 2020 were included. Demographic, radiographic, intraoperative, and postoperative data were compared between the 6 patients with ND and 9 patients without ND after ambulation. Study 2: The primary (incidence of ND after ambulation) and the secondary (postoperative hospital stay) outcomes were compared between 15 patients with a multi-rod construct since 2020 (multi-rod group) and 15 patients with a dual-rod construct before 2020 (dual-rod group; patients who were indicated in study 1).ResultsStudy 1: ND after ambulation tends to occur only in the upper or middle thoracic spine. The mean maximum OPLL occupation ratio was significantly different between the groups (ND vs non-ND, 67.7% vs 53.4%; p = .021). Study 2: The incidence of ND after ambulation (dual-rod vs multi-rod, 40% vs 6.7%; p = .040) and the mean duration of the postoperative hospital stay (dual-rod vs multi-rod, 51.2 days vs 25.6 days; p = .007) were significantly different between the groups.ConclusionsImmediate ND after ambulation occurs in the upper or middle thoracic spine, and a higher maximum OPLL occupation ratio is a significant risk factor. Multi-rod reinforcement can reduce its incidence, regardless of maximum OPLL occupation ratio, and duration of postoperative hospital stay, which could be a potential preventative measure.
Keywords: multi-rod construct; neurological deterioration; ossification of the posterior longitudinal ligament; posterior decompression and fusion; thoracic spine.