辻 崇

STUDY DESIGN: Prospective, multicenter, nationwide study. OBJECTIVE: To investigate perioperative complications and risk factors in surgery for thoracic ossification of the posterior longitudinal ligament (T-OPLL) using data from the registry of the Japanese Multicenter Research Organization for Ossification of the Spinal Ligament. SUMMARY OF BACKGROUND DATA: There is no prospective multicenter study of surgical complications and risk factors for T-OPLL, and previous multicenter retrospective studies have lacked details. METHODS: Surgical methods, preoperative radiographic findings, pre- and postoperative thoracic myelopathy (Japanese Orthopaedic Association [JOA] score), prone and supine position test (PST), intraoperative ultrasonography, and intraoperative neurophysiological monitoring (IONM) were investigated prospectively in 115 cases (males: 55, females: 60, average age 53.1 y). Factors related to perioperative complications and risk factors for postoperative motor palsy were identified. RESULTS: Posterior decompression and fusion with instrumentation with or without dekyphosis was performed in 85 cases (74%). The JOA recovery rate at 1 year after surgery in all cases was 55%. Motor palsy occurred postoperatively in 37 cases (32.2%), with a mean recovery period of 2.7 months. A long recovery period for postoperative motor palsy was significantly associated with a high number of T-OPLL levels (P < 0.0001), lower preoperative JOA score (P < 0.05), and greater estimated blood loss (P < 0.05). Perioperative complications or postoperative motor palsy were significantly related to a higher number of T-OPLL levels, comorbid ossification of ligamentum flavum rate, lower preoperative JOA score, higher preoperative positive PST rate, more surgical invasiveness, a lower rate of intraoperative spinal cord floating in ultrasonography, and higher rate of deterioration of IONM. CONCLUSION: This study firstly demonstrated the perioperative complications with high postoperative motor palsy rate in a nationwide multicenter prospective study. Surgical outcomes for T-OPLL should be improved by identifying and preventing perioperative complications with significant risk factors. LEVEL OF EVIDENCE: 3.

Background: Cost-utility analysis of surgery for degenerative lumber spondylolisthesis (DS) is essential for healthcare providers and patients to select appropriate treatment. The purpose of this study was to review the cost-utility of decompression alone versus decompression with fusion for DS. Methods: A retrospective review of 99 consecutive patients who were treated for Meyerding grade 1 DS at two representative spine centers was performed. Patients with significant spinal instability were treated by decompression with fusion (F group, 40 patients) all others were treated by decompression surgery alone (D group, 59 patients). All patients were followed for three years. Demographic and radiographic data, health-related quality of life (HRQoL), and the direct cost for surgery were analyzed, and the incremental cost-effectiveness ratio (ICER) was determined using cost/quality-adjusted life years (QALY). Results: There were no differences between the groups in baseline demographics (D vs. F: age 68 ± 9 vs. 66 ± 7 years 37% vs. 40% female) or HRQoL (ODI: D, 41 ± 16 vs. F, 46 ± 13%). The F group had a higher initial-surgery cost ($18,992 ± 2932) but lower reoperation frequency (7%) than the D group ($7660 ± 2182 and 12%, respectively). The three-year total direct cost was higher for F than for D ($19,222 ± 3332 vs. $9668 ± 6,168, p =.01). ICER was higher for F at one year ($136,408 ± 187,911 vs. $237,844 ± 212,049, p &lt .01), but was comparable for F and D at three years (D, $41,923 ± 44,503 vs. F, $51,313 ± 32,849, p =.17). Conclusion: At the three-year follow-up, the two methods had comparable cost-utility. Both methods were cost-effective (defined as an ICER within three times the per-capita gross domestic product).

Purpose: Hinge-like hyper-mobility is occasionally observed at the atlanto-occipital (O-C1) joint. However, it has not been clear if this kind of hinge-like hyper-mobility at the O-C1 joint should be regarded as “pathologic”, or referred to as “instability”. To solve this issue, we aimed to establish a reliable radiographic assessment method for this specific type of O-C1 instability and figure out the “standard value” for the range of motion (ROM) of the O-C1 joint. Methods: To figure out the standard range of the O-C1 angle, we acquired magnetic resonance imaging (MRI) sagittal views of the cervical spine for 157 healthy volunteers [average: 37.4 year-old (yo)] without spine diseases, at neutral, maximum flexion and maximum extension positions. Results: The average value (AVE) for ROM of O-C1 angle was 9.91°. The standard value for ROM of O-C1 angle was calculated as 0°–21°. There was no statistically significant gender difference. We also found that the older population (≧ 40 yo) significantly had a larger ROM of O-C1 angle (AVE: 11.72°) compared to the younger population (&lt  40 yo) (AVE: 8.99°). Conclusions: We consider that hinge-like instability at O-C1 joint, which cannot be assessed by measuring Powers ratio, can be assessed by measuring the range of O-C1 angles using dynamic-MRI. Evaluation of O-C1 instability is important especially when we perform surgical treatment for diseases with upper cervical instability (such as retro-odontoid pseudotumor). We consider that the current study provides important information in such a case.

Although the number of patients with intervertebral disc (IVD) degeneration is increasing in aging societies, its etiology and pathogenesis remain elusive and there is currently no effective treatment to prevent this undesirable condition. The unfolded protein response (UPR) is a cellular machinery that plays critical roles in handling endoplasmic reticulum (ER) stress, a condition caused by the accumulation of unfolded proteins in the ER lumen. This study aimed to elucidate the potential role of the UPR mediated by pancreatic endoplasmic reticulum kinase (PERK), one of the major ER stress sensors in mammalian cells, in the development of IVD degeneration. IVD degeneration was artificially induced in Wister rats by percutaneously puncturing the coccyx IVDs and human IVDs were collected from patients who underwent spinal surgery. Expression of the UPR target genes was elevated in degenerative IVDs in both humans and rats. The induction of ER stress in annulus fibrosus cells significantly increased the transcripts for tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) in a nuclear factor (NF)-κB pathway-dependent manner. The expression of TNF-α and IL-6 was significantly reduced by treatment with a selective PERK inhibitor, GSK2606414, and by gene silencing against PERK and activating transcription factor 4 (ATF4) transcripts. Our findings indicate that the UPR mediated by the PERK pathway is causally related to the development of IVD degeneration, suggesting that PERK may be a potential molecular target for suppressing the degenerative changes in IVDs. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1334–1345, 2018.