Treatment of Lumbar Degenerative Disease with a Novel Interlaminar Screw Elastic Spacer Technique: A Finite Element Analysis.

A novel interlaminar elastic screw spacer technique was designed to maintain lumbar mobility in treating lumbar degenerative diseases. A validated finite element model of L4/5 was used to establish an ISES-1/2 model and an ISES-1/3 model based on different insertion points, a unilateral fixation model and a bilateral fixed model based on different fixation methods, and a Coflex-F model based on different implants. The elastic rods were used to fix screws. Under the same mechanical conditions, we compared the biomechanical characteristics to investigate the optimal entry point for ISES technology, demonstrate the effectiveness of unilateral fixation, and validate the feasibility of the ISES technique. Compared to ISES-1/3, the ISES-1/2 model had lower intradiscal pressure, facet cartilage stress, and posterior structural stress. Compared to the ISES-BF model, the ISES-UF model had lower intervertebral pressure, larger mobility, and smaller stress on the posterior structures. The ISES model had a similar intervertebral pressure and limitation of extension as the Coflex-F model. The ISES model retained greater mobility and reduced the stress on the facet cartilage and posterior structure compared with the Coflex-F model. Our study suggests that the ISES technique is a promising treatment of lumbar degenerative diseases, especially those with osteoporosis.

Development and validation of a predictive model for spinal fracture risk in osteoporosis patients.

BACKGROUND: Spinal osteoporosis is a prevalent health condition characterized by the thinning of bone tissues in the spine, increasing the risk of fractures. Given its high incidence, especially among older populations, it is critical to have accurate and effective predictive models for fracture risk. Traditionally, clinicians have relied on a combination of factors such as demographics, clinical attributes, and radiological characteristics to predict fracture risk in these patients. However, these models often lack precision and fail to include all potential risk factors. There is a need for a more comprehensive, statistically robust prediction model that can better identify high-risk individuals for early intervention. AIM: To construct and validate a model for forecasting fracture risk in patients with spinal osteoporosis. METHODS: The medical records of 80 patients with spinal osteoporosis who were diagnosed and treated between 2019 and 2022 were retrospectively examined. The patients were selected according to strict criteria and categorized into two groups: Those with fractures (n = 40) and those without fractures (n = 40). Demographics, clinical attributes, biochemical indicators, bone mineral density (BMD), and radiological characteristics were collected and compared. A logistic regression analysis was employed to create an osteoporotic fracture risk-prediction model. The area under the receiver operating characteristic curve (AUROC) was used to evaluate the model's performance. RESULTS: Factors significantly associated with fracture risk included age, sex, body mass index (BMI), smoking history, BMD, vertebral trabecular alterations, and prior vertebral fractures. The final risk-prediction model was developed using the formula: (logit [P] = -3.75 + 0.04 × age - 1.15 × sex + 0.02 × BMI + 0.83 × smoking history + 2.25 × BMD - 1.12 × vertebral trabecular alterations + 1.83 × previous vertebral fractures). The AUROC of the model was 0.93 (95%CI: 0.88-0.96, P < 0.001), indicating strong discriminatory capabilities. CONCLUSION: The fracture risk-prediction model, utilizing accessible clinical, biochemical, and radiological information, offered a precise tool for the evaluation of fracture risk in patients with spinal osteoporosis. The model has potential in the identification of high-risk individuals for early intervention and the guidance of appropriate preventive actions to reduce the impact of osteoporosis-related fractures.

FDG PET/CT in a Case of Pure Ductal Adenocarcinoma of the Prostate With Osteolytic Metastases and Normal PSA Level.

ABSTRACT: Prostatic ductal adenocarcinoma is an uncommon aggressive subtype of prostate carcinoma. It is more likely to present with advanced stage and lower prostate-specific antigen. We describe FDG PET/CT findings in a case of pure prostatic ductal adenocarcinoma with lymph node, bone and lung metastases, normal serum prostate-specific antigen level, and elevated serum carbohydrate antigen 19-9 and carbohydrate antigen 724 levels. The primary tumor, and lymph node and bone metastases were hypermetabolic. All the bone metastases were osteolytic. The multiple lung metastases showed no significant FDG uptake, which may be due to small size.

Biomechanical evaluation of a short-rod technique for lumbar fixation surgery.

Objective: The purpose of this study was to analyze the stability and instrument-related complications associated with fixation of the lumbar spine using the Short-Rod (SR) technique. Methods: Using finite element analysis, this study assessed the stability of a bilateral lumbar fixation system when inserting the pedicle screws at angles of 10°, 15°, and 20° to the endplate in the sagittal plane. Using the most stable construct with a screw angle, the model was then assessed with different rod lengths of 25, 30, 35, and 45 mm. The optimal screw inclination angle and rod length were incorporated into the SR model and compared against traditional parallel screw insertion (pedicle screws in parallel to the endplate, PPS) in terms of the stability and risk of instrument-related complications. The following parameters were evaluated using the validated L4-L5 lumbar finite element model: axial stiffness, range of motion (ROM), stress on the endplate and facet joint, von-Mises stress on the contact surface between the screw and rod (CSSR), and screw displacement. Results: The results showed that the SR model with a 15° screw inclination angle and 35 mm rod length was superior in terms of construct stability and risk of complications. Compared to the PPS model, the SR model had lower stiffness, lower ROM, less screw displacement, and lower stress on the facet cartilage, the CSSR, and screws. However, the SR model also suffered more stress on the endplate in flexion and lateral bending. Conclusion: The SR technique with a 15° screw inclination and 35 mm rod length offers good lumbar stability with a low risk of instrument-related complications.

Perioperative Coagulation Profile with Thromboelastography in Aspirin-Treated Patients Undergoing Posterior Lumbar Fusion.

BACKGROUND: It has been generally recommended that platelet function may recover after the recommended 5-day discontinuation period prior to operation. The technique of thromboelastography has been demonstrated to monitor intraoperative platelet function in liver transplantation and coronary bypass surgery. However, there is a dearth of literature that addresses the utility of thromboelastography in aspirin-treated patients undergoing fusion. OBJECTIVES: To introduce a functional method of monitoring coagulation and validate the effectiveness of thromboelastography perioperatively in assessing aspirin-treated patients undergoing posterior lumbar fusion. STUDY DESIGN: This research used a retrospective study design. SETTING: Orthopedic Department of Changhai Hospital,Shanghai, China and Orthopedic and Anesthesia Department of Changzheng Hospital. METHODS: Eighty patients were divided into aspirin-naive and aspirin-treated groups in this study. They had equally undergone lumbar fusion surgery for at least one or more segments between January and June 2018. They matched for age, gender, number of fused segments, and surgical procedures. The coagulation profile, including the reaction time (R), kinetics (K), maximal amplitude (MA), alpha-angle, and coagulation index (CI), platelet inhibition ratio (PIR) was analyzed by thromboelastogram (TEG) prior to operation and on preoperative days 1, 3, and 5. Correlation analysis included parameters such as waiting time, intraoperative blood loss, and postoperative drainage. RESULTS: Perioperatively, the TEG values including R, K, MA, alpha-angle, and CI, PIR, and correlation analysis showed no significant difference between the 2 groups, respectively (P > 0.05). LIMITATIONS: First, the relatively small number of patients recruited limits control over other factors; larger studies may need to confirm our findings. Second, the patients were objectively less healthy with more medication treatment, which may result in a variance in the amount of blood loss. Randomized controlled studies are needed to further confirm these results. CONCLUSIONS: TEG may be a helpful method to monitor perioperative platelet function in aspirin-treated patients undergoing fusion. It may be comparatively safe to relax the restriction of the aspirin-discontinued therapeutic window to approximately 2 to 3 days prior to surgery.

Thymic Granuloma Mimicking Malignancy on 18F-FDG PET/CT.

We present a case with an unexpected nodule in the thymus showing increased F-FDG uptake on PET/CT. The nodule was surgically removed. Histopathologic examination revealed granuloma in the thymus. This case indicates physicians and radiologists must be aware that although thymic granuloma is rare, it should be included in the differential diagnosis of the thymic lesions with F-FDG accumulation along with neoplastic and nonneoplastic conditions.