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BackgroundAcetabular reconstruction using an ice-cream cone prosthesis has been a reliable reconstruction option following pelvic tumour resection. However, it remains unknown which factor determines the success of this procedure. We aimed to determine risk factors for complications and functional loss in acetabular reconstruction using an ice-cream cone prosthesis.Patients and methodsFifty-four patients with malignant bone tumours who underwent acetabular reconstruction using an ice-cream cone prosthesis between 2004 and 2016 were studied. The bone–stem ratio was calculated as the ratio of the inserted length into the bone per the entire stem length.ResultsA total of 26 (48%) patients had at least one complication and 11 patients (20%) required surgical interventions. The complication rates were 71% and 40% with a bone–stem ratio ≤ 50% and > 50%, respectively (p = 0.026), and the bone–stem ratio significantly stratified the risk of complications (≤ 50%: OR, 4.67 versus > 50%; p = 0.048). The mean MSTS score at the final follow-up was 60% (range 23–97%): the scores were significantly lower in patients with complications/leg-length discrepancy (52%) than in those without (79%; p = 0.002). The mean score with a bone–stem ratio ≤ 50% was significantly lower than the score with a ratio > 50%, especially in patients who underwent non-navigated reconstructions (33% versus 64%; p = 0.001).ConclusionThe inserted length of the coned stem into residual bone was predictive of complications and functional outcome. Surgical indication for this procedure should be considered with the size of the remaining ilium to stabilise the prosthesis with a coned stem longer than half length.

Background Few reports have described clinical features, prognosis and prognostic factors of osteosarcoma patients according to age. Methods Using the Bone and Soft Tissue Tumor Registry in Japan, we identified 1043 osteosarcoma patients including 760 who were younger than 40 years, 173 aged between 41 and 64 years, and 110 patients older than 65 years. We extracted data on patient demographics and prognosis. Prognostic factors for patients older than 65 years or other age groups were analyzed. Results Patients older than 65 years showed a significantly higher proportion of tumors arising in the trunk and with metastasis at diagnosis, and their 5-year disease-specific survival (DSS) rate was 32.7%. Multivariate analysis showed that the presence of metastasis at diagnosis [hazard ratio (HR): 3.04; 95% confidence interval (CI), 1.63–5.69; P  < 0.001] and tumors > 16 cm in size (HR: 2.84 compared with < 8 cm; 95% CI, 1.16–6.97; P  = 0.023) were significantly associated with worse DSS. The 5-year DSS was 39.1% in 80 patients older than 65 years without metastasis at diagnosis. Methotrexate was used in only 5.0% of these patients. Adjuvant chemotherapy was not significantly associated with better DSS ( P  = 0.323) in this generation and aged between 41 and 64 years ( P  = 0.566), although adjuvant chemotherapy yielded significantly better survival in patients younger than 40 years ( P  < 0.001). Conclusions Analysis of this cohort of osteosarcoma patients revealed some unique clinical, therapeutic and prognostic features according to age groups in the largest cohort. Adjuvant chemotherapy was not associated with a better DSS in the group of patients aged between 41 and 64 years or older than 65 years.

BackgroundPrimary tumor resection is the mainstay of treatment for undifferentiated pleomorphic sarcoma (UPS); however, the necessity of adjuvant chemotherapy has been debated. We aimed to clarify the effect of adjuvant chemotherapy on survival rates in patients with UPS with localized and resectable primary lesions.MethodsThis retrospective analysis included data of 2112 patients with localized UPS arising in the extremities and trunk, extracted from a registry in Japan. We estimated overall survival (OS), identified prognostic factors, and adjusted patient characteristics in the two groups treated with or without chemotherapy using propensity score matching (PSM).ResultsThe 5-year OS rate was 79.4%. In multivariate OS analysis, adjuvant chemotherapy was a good prognostic factor (hazard ratio 0.65; 95% confidence interval 0.48–0.9, P = 0.009). Large tumor size was the poorest prognostic factor, and OS decreased with the tumor size (P < 0.0001). In all patients, adjuvant chemotherapy prolonged OS (5-year OS: 82.3% vs. 78.6%, P = 0.03). Adjuvant chemotherapy did not affect OS in patients with tumor size < 5 cm; the benefit was strong in patients with tumor size 10 to < 15 cm (5-year OS: 79.5% vs. 66.8%, P = 0.003). Adjuvant chemotherapy efficacy was not pronounced in patients with tumor size 5 to < 10 cm (5-year OS: 87% vs. 80%, P = 0.06) and ≥ 15 cm (5-year OS: 60.7% vs. 49.5%, P = 0.08). After PSM, adjuvant chemotherapy was significantly associated with improved OS (P = 0.02).ConclusionsIn patients with localized UPS, adjuvant chemotherapy tended to improve OS when tumors were ≥ 5 cm, especially when they were 10 to < 15 cm.

Introduction Mortality following hip fracture surgery is higher in patients with dementia than those without; however, few large-scale studies have investigated postoperative in-hospital complications in such patients. The aim of this study was to elucidate the complications that occur after hip fracture surgery in patients with and without dementia using a large national database. Materials and methods We retrospectively identified patients aged ≥70 years who underwent hemiarthroplasty, osteosynthesis for femoral neck fracture or osteosynthesis for intertrochanteric fracture, and compared the occurrence of postoperative complications between patients with and without dementia. Multivariate logistic regression analysis was performed to adjust for patient characteristics and hospital factors. Results A total of 87,654 patients were included in this study, including 9419 with dementia. Compared with the non-dementia group, the dementia group showed a higher incidence of overall postoperative complications [odds ratio (OR) 1.45; p  < 0.001), surgical site infection (OR 1.58; p  = 0.004), urinary tract infection (OR 1.87; p  < 0.001) and respiratory complications (OR 1.49; p  < 0.001). The rate of postoperative complications was higher for all types of hip fracture surgery. The occurrence of a postoperative complication was significantly higher in patients aged ≥80 years (OR 1.37; p  < 0.001) and those with dementia (OR 1.45; p  < 0.001), any type of malignancy (OR 1.42; p  < 0.001), a history of cardiovascular disease (OR 1.33; p  < 0.001), a history of cerebrovascular disease (OR 1.15; p  = 0.029), chronic renal failure (OR 1.36; p  < 0.001), liver cirrhosis (OR 1.41; p  < 0.001) or blood transfusion after surgery (OR 1.49; p  < 0.001). Conclusions Our results highlight the need to pay particular attention to surgical site infection, urinary tract infection and respiratory complications in patients with preoperative dementia after hip fracture surgery. These results provide additional useful evidence to inform the management of these patients.

Background Currently, there are few reports regarding predictors of postoperative complications and short-term mortality after surgery for pathological femur fracture related to bone metastasis. Methods Using data from the Japanese Diagnosis Procedure Combination Database from 2007 to 2012, we retrospectively identified 1497 patients who underwent internal fixation ( n  = 1073) or proximal femur resection and endoprosthetic reconstruction of the proximal femur ( n  = 424) for pathological femur fracture related to bone metastasis. Multivariable logistic regression analysis was performed to examine the relationship of various factors with postoperative complications and 30-day mortality. Results The overall 30-day mortality after surgery was 2.6 %, and the proportion of postoperative complications was 12.1 %. Multivariable logistic regression analysis showed that postoperative complications overall were significantly associated with older age [odds ratio (OR), 2.15; 95 % confidence interval (CI) 1.23–3.74 for age ≥80 vs. ≤59 years]; lung carcinoma (OR 2.05; 95 % CI 1.47–2.86); esophageal carcinoma (OR 4.41; 95 % CI 1.57–12.43); higher Charlson Comorbidity Index (OR 1.50; 95 % CI 1.03–2.18 for ≥9 vs. 8); and blood transfusion (OR 1.57; 95 % CI 1.14–2.15). Thirty-day mortality also was significantly higher in patients with rapid-growth tumors, visceral metastasis, internal fixation, and no postoperative chemotherapy in the univariate analysis. Conclusions Older age, type of primary tumor, higher Charlson Comorbidity Index, and blood transfusion were associated with higher morbidity. These findings can provide important information to assess perioperative risk in patients with pathological femur fracture related to bone metastasis.

The seasonality and epidemiology of viral acute respiratory infections (ARIs) have changed since the coronavirus disease 2019 pandemic. However, molecular-based ARI surveillance has not been conducted in Japan. We developed a regional surveillance program to define the local epidemiology of ARIs. Between December 2023 and March 2024, 2,992 upper respiratory samples collected from patients suspected of having ARIs at five facilities in Kyoto City, Japan, were tested for SARS-CoV-2, influenza virus, and respiratory syncytial virus (RSV) using RT‒PCR. Samples negative for these viruses were randomly selected for testing with the FilmArray Respiratory Panel, and the detection rates of other viruses were estimated. SARS-CoV-2, influenza virus, and RSV were detected in 598 (20.3%), 165 (5.6%), and 40 (1.4%) of the 2,949 samples with valid RT‒PCR results, respectively. The most prevalent viruses in the < 6, 6–17, 18–64, and ≥ 65 year age groups were rhinovirus/enterovirus, RSV, and SARS-CoV-2; influenza virus, seasonal coronavirus, and rhinovirus/enterovirus; SARS-CoV-2, seasonal coronavirus, and influenza virus; and SARS-CoV-2, seasonal coronavirus, and influenza virus, respectively. Significant differences in the detection rates of these viruses were detected between the age groups. This study highlights the importance of age-stratified molecular-based surveillance for a comprehensive understanding of the epidemiology of ARIs.

The role of neoadjuvant chemotherapy for localized synovial sarcoma is still controversial. This study aimed to explore the influence of neoadjuvant chemotherapy combined with surgery in localized synovial sarcoma through analysis of our hospital's patient records. A total of 122 patients diagnosed with synovial sarcoma were enrolled in this study from January 1980 to December 2016 at the Cancer Institute Hospital of The Japanese Foundation for Cancer Research. The impact of neoadjuvant chemotherapy on overall survival was assessed to show how clinicopathological factors (e.g. age, tumor size, treatment, dose intensity, pathological pattern and histological grading) influenced patient prognosis. Among 106 patients, 76 (71.7%) received neoadjuvant chemotherapy and 30 (28.3%) did not. The median follow-up was 39.2 (range=12-286) months. The 5-year and 10-year overall survival rates were 65.4% and 58.4% respectively. The tumor size and histological grade influenced the patient's overall survival (p<0.05). Among the patients with grade 2 tumor, tumor size did not influence prognosis. Neoadjuvant chemotherapy improved the overall survival of patients who had grade 3 tumors. Treatment with neoadjuvant chemotherapy proved beneficial for high-risk patients with grade 3 synovial sarcoma but was not effective for those with low-risk and grade 2 tumor. Tumor size and histological grade were important factors in patient prognosis but had no connection with pathological patterns.

We study the distribution of prime numbers that satisfy the Goldbach equation. In particular, we discuss the small gaps between such prime numbers using E. Bombieri and H. Davenport’s method. We prove that, for almost all even integer N , there exist primes p , p ′ which N - p , N - p ′ are also prime and | p - p ′ | < 0.8201 . . . S ( N ) - 1 ( log N ) 2 where S ( N ) denotes the singular series for the Goldbach conjecture.

Background Schwannomas are well-encapsulated, benign neoplasms, and enucleation is a standard operation procedure. The incidence of neurological complications after surgical treatment for schwannomas of the extremities varies, and there is no consensus concerning predictive factors for complications. The aim of this study was to elucidate predictive factors for complications after surgical treatment of schwannomas that develop in the major nerves of the extremities. Methods A total of 139 patients with 141 schwannomas arising in major nerves were retrospectively analyzed. Data regarding preoperative clinical features, the postoperative neurological complications, and clinical course of complications, with a median follow-up period of 2 months (range, 0.5–96), were obtained. Predictive factors for complications were statistically analyzed. Results Postoperative complications occurred in 49 lesions (34.8%), including 42 with sensory disturbance and 8 with motor weakness. In univariate analysis, older age, tumors originating from the upper extremity, and major motor nerve involvement were associated with a higher complication rate ( p  = 0.03, p  = 0.003, and p  = 0.001, respectively). In multivariate analysis, major motor nerve involvement was an independent predictive factor for postoperative complications ( p  = 0.03). Almost all complications gradually improved, but 6 out of 8 patients with motor weakness did not show full recovery at the final follow-up. Conclusions Schwannomas originating from major motor nerves can lead to a higher risk for postoperative complications.

Background/Aim: We analyzed the process of healing at osteotomy sites and timing of achievement of full weight-bearing in sarcoma patients who underwent hemicortical or intercalary reconstruction using the extracorporeal irradiated autologous bone graft technique. Patients and Methods: We studied 10 patients who had undergone tumor resection and reconstruction with hemicortical extracorporeal irradiated autologous bone graft at mid-shaft femur or tibia. The control group consisted of 30 patients who received the reconstruction using intercalary bone graft. Results: Full weight-bearing was achieved in all 10 patients at a median time of 4.8 months. Function was excellent in all patients. When comparing the clinical outcome among the patients who received intercalary and hemicortical grafts, the duration to full weight-bearing achievement in patients who received hemicortical graft was shorter than that in those with intercalary graft. Conclusion: Early full weight-bearing may be achieved in patients undergoing hemicortical resection and reconstruction using extracorporeal irradiated autologous bone graft.