Hiroaki Nakamura

Study Design: Retrospective multicenter cohort study.Purpose: This study aimed to evaluate the incidence of cage subsidence and its impact on the clinical outcomes of anterior–posterior spinal fixation (APSF) for osteoporotic vertebral fractures (OVFs). It also aimed to identify the risk factors for cage subsidence.Overview of Literature: The risk factors for cage subsidence after APSF for OVFs remain unclear.Methods: This multicenter retrospective cohort study included patients who underwent combined APSF using an expandable cage system, with a minimum 1-year follow-up at multiple centers. Patients were divided into cage subsidence (n=53) and non-subsidence (n=47) groups. Demographic data, surgery-related factors, and radiographic parameters were analyzed. After univariate analysis of factors associated with cage subsidence, multivariate logistic regression was used to identify related factors.Results: The demographic data showed a significant difference in Hounsfield unit (HU) (102.6±28.3 vs. 80.0±30.6, p=0.005) and endplate injury (p<0.001). Furthermore, 1A1B fixation was significantly more common in the subsidence group (p<0.001). Radiographic data showed significant differences in Δlocal kyphosis (supine-standing) (−7.1°±9.2° vs. −14.6°±11.5°, p=0.001). Multivariate analysis showed that Δlocal kyphosis (supine-standing) (adjusted odds ratio [aOR], 12.8; p=0.010), HU (aOR, 8.1; p=0.033), fixation range (aOR, 8.2; p=0.020), and endplate injury (aOR, 18.8; p=0.011) were significant risk factors for subsidence.Conclusions: Intraoperative endplate injury, low HU (<87.5), short fusion, and preoperative vertebral instability (Δlocal kyphosis [supinestanding] <−14) were identified as risk factors for cage subsidence in APSF. Therefore, extending the fusion levels in patients with low HU values and significant preoperative vertebral instability should be considered to avoid intraoperative endplate injury.

Study Design.: Retrospective cohort study Objective.: This study aimed to evaluate the prevalence of patient-reported bladder dysfunction in individuals with degenerative cervical myelopathy (DCM), its impact on quality of life (QOL), and postoperative bladder function and QOL improvements. Summary of Background Data.: DCM frequently causes bladder dysfunction, in addition to limb neurological deficits, which substantially impair QOL. Although it is well established that posterior decompression surgery improves neurological function, its effect on patient-reported bladder function remains unclear. Methods.: We retrospectively analyzed prospectively collected data from 163 patients who underwent cervical laminoplasty for DCM during 2019–2021. Bladder dysfunction and QOL were assessed using the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ), particularly its bladder dysfunction (CMEQ-BD) and QOL (CMEQ-QOL) domains. Patients with a preoperative CMEQ-BD score of 20-point increase or 2-year postoperative CMEQ-BD score of ≥90. Results.: Preoperative patient-reported bladder dysfunction was identified in 123 of the 163 patients. Compared with patients without bladder dysfunction, those with bladder dysfunction were significantly older and had worse QOL. Multivariate analysis showed that bladder dysfunction was independently associated with lower preoperative QOL (β=−0.167, P =0.031). At postoperative 2 years, only 27 of the 123 patients (22.0%) experienced postoperative bladder function improvement. No demographic or clinical factors were significantly associated with postoperative bladder function recovery. However, patients with improved bladder function showed significantly greater improvements in neurological function (JOA score, P =0.007) and QOL ( P <0.001) than those without improvement. Conclusions.: Patient-reported bladder dysfunction was highly prevalent in patients with DCM and was independently associated with impaired QOL. However, bladder dysfunction rarely improved postoperatively. These findings suggest that considering bladder dysfunction may be helpful when determining the optimal surgery timing in patients with DCM. Level of Evidence.: Level Ⅲ

... Asian Spine Journal 2026;20(4):825-826.

Objective Osteoporosis is a well-known risk factor for incident vertebral fractures (VFs) and postoperative mechanical complications. However, the specific Hounsfield unit (HU) and vertebral bone quality (VBQ) cutoff values for predicting these complications, as well as the diagnostic and clinical significance of the differences between these two measurements, remain unclear. This study sought to evaluate the predictive value of HU and VBQ scores and to establish specific cutoff points for osteoporosis-related complications in lumbar spine surgery. Additionally, we analyzed whether combining HU and VBQ scores enhanced their predictive usefulness and whether the differences between them were clinically significant using principal component analysis (PCA). Methods We examined 189 patients with lumbar spinal stenosis who underwent microscopic bilateral decompression using a unilateral approach or short segmental fixation between 2010 and 2016. Patients who underwent prior lumbar surgery were excluded, and a minimum 5-year follow-up was conducted. Surgical indications were based on preoperative evaluation of segmental instability. HU values and VBQ scores were measured using computed tomography and magnetic resonance imaging, respectively. Osteoporosis-related complications, including incident VFs, and mechanical complications, such as proximal junctional fractures, cage subsidence, and screw loosening, were assessed. Results For predicting osteoporosis-related complications, cutoff points of HU < 95.5 and VBQ > 3.49 were identified, both demonstrating good predictive accuracy without a significant difference in the area under the curve. Multivariate logistic regression confirmed low HU and high VBQ as independent risk factors (adjusted odds ratio = 5.57 and 3.42, respectively; p < 0.001). Additionally, PCA revealed that the concordance of these scores significantly distinguished patients with complications from those without complications (odds ratio, 3.77; p < 0.001), while the differences between these scores lacked clinical significance. Conclusion This study demonstrated that both HU and VBQ scores effectively predicted postoperative osteoporosis-related complications, with no significant difference in predictive ability. Optimal cutoff values were identified at approximately ≤ 100 for HU and ≥ 3.5 for VBQ, and the difference between these two scores lacked clinical significance. These cut-offs for HU and VBQ can serve as practical thresholds for risk assessment, enabling spinal surgeons to use these scores as opportunistic tools for identifying patients at an elevated risk of osteoporosis-related complications after lumbar spine surgery.

A referral from a primary physician is a crucial initial diagnostic intervention for the management of osteosarcoma. We reviewed the awareness of primary physicians regarding the radiological findings of osteosarcoma through their referral documents. Referral documents of 40 patients (27 male and 13 female; median age, 19 [8–81] years) with osteosarcoma were retrospectively investigated. The documents were examined for suggested supplementary radiological procedures, presence or absence of a descriptive keyword for the radiological findings of osteosarcoma, periosteal reaction, matrix, soft tissue mass, type of border of the lesion, and type of bone destruction, followed by an assessment of the diagnostic radiologists’ findings. The keywords “periosteal reaction,” “matrix,” “soft tissue extension,” “border of the lesion,” and “type of bone destruction” were described in 5 (7.5%), 5 (15%), 4 (10%), 0 (0%), and 7 (17.5%) cases by the primary physicians, respectively. Records with “periosteal reaction,” “matrix,” “soft tissue mass,” “type of border of the lesion,” and “type of bone destruction” were described in 5 (31.25%), 5 (31.25%), 10 (62.5%), 3 (18.8%), and 3 (18.8%) radiologic findings of the diagnostic radiologists, respectively. The descriptions of keywords for radiological findings suggesting osteosarcoma in referral documents from primary physicians seemed generally insufficient. More enhanced and comprehensive awareness of the typical radiological findings of osteosarcoma is necessary to prevent diagnostic delays.

Background In the 2015 guidelines for the prevention and treatment of osteoporosis in Japan, the young adult mean percentage (%YAM) of the lumbar spine or femoral neck is required to diagnose osteoporosis in patients with distal radius fracture (DRF). When the %YAM of multiple locations is measured, the lower %YAM is adopted for the diagnosis. If the area with a lower %YAM is known, bone mineral densitometry tests may only need to be performed at one site. This study aimed to compare the lumbar and femoral neck %YAMs of patients with DRFs to find out the lower %YAM site. Methods We retrospectively compared the %YAM of the lumbar and femoral neck of patients with DRFs who underwent open reduction and internal fixation (ORIF) between April 2018 and March 2023. We also measured the lumbar and femoral neck %YAM of patients with hip fractures (HFs) treated by ORIF, bipolar hemiarthroplasty, or total hip arthroplasty. Results The %YAM of the femoral neck was significantly lower than that of the lumbar region in the DRF group. In the HF group, the lumbar %YAM was significantly higher than that of the femoral neck. Conclusions In patients with DRFs, the %YAM of the femoral neck was significantly lower than the lumbar %YAM. The lumbar %YAM appears to be less reliable than the %YAM of the femoral neck because of the lumbar degenerative changes. Therefore, we believe that the %YAM of the femoral neck should be measured first if osteoporosis is suspected in patients with DRF. Level of evidence III Case–control study.

Study Design: A retrospective study.Purpose: This study aimed to determine the impact of increased Hounsfield unit (HU) values for metastatic spinal lesions measured via computed tomography on the overall survival of patients with non-small-cell lung cancer (NSCLC) and identify factors associated with increased HU values in metastatic spinal lesions.Overview of Literature: Previous studies have underscored the utility of the HU as a marker of treatment response in metastatic bone lesions. However, no prior studies have explored the relationship between HU changes in response to treatment and overall survival in patients with NSCLC.Methods: This study included a total of 85 patients between 2016 and 2021. Nonsurgical treatments were provided by the respiratory medicine department. HU values for metastatic spinal lesions were evaluated upon diagnosis of spinal metastasis (baseline) and at 3, 6, and 12 months thereafter. Patients were then divided into two groups based on the median HU increase from baseline to 3 months. Overall survival was assessed using the Kaplan-Meier method.Results: Based on the median change in HU value (124), 42 and 43 patients were categorized into the HU responder and non-responder groups, respectively. The median overall survival was significantly longer in the HU responder group than in the HU non-responder group (13.7 months vs. 6.4 months, p <0.001). Multiple linear regression analysis revealed that the use of antiresorptive agents and molecularly targeted therapies were factors significantly associated with an increase in HU.Conclusions: An increase in HU values for metastatic spinal lesions after 3 months of treatment was correlated with a significantly longer overall survival in patients with NSCLC. Thus, HU measurements may not only serve as an easy and quantitative approach for evaluating treatment response in metastatic spinal lesions but also predict overall survival.

Background/Objective: Anti-tumor effects of plasma-activated medium (PAM) were demonstrated using various malignant tumors. However, the anti-tumor effect of PAM on synovial sarcoma remains unclear. Therefore, we aimed to investigate the anti-tumor effects of PAM on synovial sarcoma and its underlying mechanisms, focusing on the quantitative analyses of both intracellular reactive oxygen species (ROS) and cell apoptosis. Methods: The human synovial sarcoma cell line HS-SY-II was used to investigate the cell viability after PAM treatment. We investigated the anti-tumor effects and side effects of local PAM injection in a synovial sarcoma xenograft murine model. Moreover, we observed PAM-induced intracellular ROS accumulation and cell apoptosis and assessed the involvement of intracellular ROS in the anti-tumor effects of PAM using an intracellular ROS scavenger. Results: PAM significantly decreased the viability of synovial sarcoma cells compared with untreated Dulbecco’s modified Eagle medium. Local PAM injection into a synovial sarcoma xenograft murine model significantly suppressed tumor growth, including tumor volume (p < 0.001) and weight (p = 0.031), without side effects. Regarding anti-tumor mechanisms, PAM induced significant cell apoptosis and intracellular ROS accumulation (p < 0.001). The intracellular ROS scavenger significantly inhibited the anti-tumor effect of PAM (p < 0.001). Conclusions: We confirmed the anti-tumor effects of PAM on synovial sarcoma in vitro and in vivo, as well as the absence of side effects. The underlying mechanism was suggested to involve cell apoptosis induced by intracellular ROS accumulation. Considering the various clinical issues associated with the existing treatments of synovial sarcoma, PAM is a promising new option.

Purpose This study aimed to compare the incidence of radiological adjacent segment disease (R-ASD) at L3/4 between patients with L4/5 degenerative spondylolisthesis (DS) who underwent L4/5 posterior lumbar interbody fusion (PLIF) and those who underwent microscopic bilateral decompression via a unilateral approach (MBDU) at L4/5. Our ultimate goal was to distinguish the course of natural lumbar degeneration from fusion-related degeneration while eliminating L4/5 decompression as a confounder. Methods Ninety patients with L4/5 DS who underwent L4/5 PLIF (n = 53) or MBDU (n = 37) and were followed for at least 5 years were retrospectively analyzed. Various radiographic parameters at L3/4 and L4/5 were measured before surgery and at last follow-up. Progression of facet degeneration was measured on computed tomography (Japanese Orthopaedic Association [JOA] classification); disc degeneration and spinal stenosis were measured on magnetic resonance imaging (Pfirrmann and Imagama classifications, respectively). R-ASD on plain radiography (X-ASD) was defined as reported by Okuda et al. [1]. R-ASD on CT or MRI (C/M-ASD) was defined as at least a one-grade progression in the relevant classification. JOA score for low back pain and incidence of reoperation were also evaluated. Results The mean parameters at L3/4 in the PLIF group were as follows (before surgery/at last follow-up): (1) % slip: 0.8%/1.9%, (2) change in slip: 0.7/0.4 mm, (3) segmental lordosis: 11.9°/12.1°, (4) disc arc: 7.7°/7.5°, and (5) disc height: 8.6/7.7 mm. Corresponding data in the MBDU group was: (1) % slip: 1.8%/2.4%, (2) change in slip: 0.6/0.5 mm, (3) segmental lordosis: 9.6°/10.8°, (4) disc arc: 7.7°/8.7°, and (5) disc height: 7.8/6.5 mm. Disc height at last follow-up significantly differed between the groups (p = 0.002). Progression of facet degeneration was detected in 55.1% of PLIF patients and 77.8% of MBDU patients. Progression of disc degeneration and spinal stenosis was observed in 45.2% and 36.8% of PLIF patients, respectively, and 58.9% and 36.0% of MBDU patients, respectively. Overall, the incidence of X-ASD was 17.0% in the PLIF group and 16.2% in the MBDU group. Among the patients who underwent plain radiography plus CT or MRI, the total incidence of R-ASD was 70.6% in the PLIF group and 60.0% in the MBDU group. The above rates did not significantly differ between the groups. The mean improvement rate in the JOA score for low back pain was 52.8% in the PLIF group and 52.1% in the MBDU group (p = 0.867). The incidence of revision surgery at L3/4 was 1.9% in the PLIF group and 5.4% in the MBDU group (p = 0.62). Conclusion The 5-year incidence of R-ASD at L3/4 after PLIF and MBDU in patients undergoing surgery for L4/5 DS is similar, indicating that naturally occurring lumbar degeneration is probably responsible, not fusion.

Background The combined anteversion theory is used for implant placement in total hip arthroplasty (THA). While majority of the research emphasizes the precise placement of the acetabular cup, there’s less focus on stem alignment. This study aimed to investigate the impact of the discrepancy between the preoperatively planned femoral neck osteotomy level and the actual osteotomy level during surgery on stem alignment. Materials and Methods The study involved 232 patients (258 joints) who had a total hip arthroplasty (THA) between April 2018 and December 2022 at our hospital. They were implanted with either the ACTIS stem (Depuy Synthes) or Taperloc Complete XR 123° (Zimmer Biomet)—147 joints with ACTIS stem and 111 with Taperloc stem. Three-dimensional templating software was used to evaluate preoperative planning and postoperative stem placement angles. The difference between the actual and preoperatively planned osteotomy levels was also measured. The impact of this difference in femoral neck osteotomy level on stem alignment was evaluated. Results In the ACTIS stem group, the femoral neck osteotomy level was − 0.3 ± 3.7 mm. The stem alignment had a varus of 1.8 ± 1.9°, extension of 0.1 ± 1.5°, and anteversion of 2.4 ± 5.9°, compared to preoperative plans. A positive correlation was identified between osteotomy level and varus/valgus alignment (r = 0.607, p < 0.01), with a weak correlation for anteversion (r = 0.236, p < 0.01). No correlation existed with flexion/extension. In the Taperloc stem group, osteotomy level was 2.2 ± 3.1 mm. The postoperative stem showed a varus of 1.6 ± 1.5°, extension of 0.5 ± 1.7°, and anteversion of 4.9 ± 6.5°. A correlation was observed between osteotomy level and varus/valgus alignment (r = 0.476, p < 0.01), but not with flexion/extension or anteversion. Conclusions The study examined how differences in planned vs. actual femoral neck osteotomy affect stem alignment in THA using ACTIS stem and Taperloc stem. We found that osteotomy level influenced varus/valgus alignment; mildly affected flexion/extension; and had no effect on anteversion.