Objective:To investigate the risk factors of pleural effusion after spinal separation surgery for patients with spinal metastatic tumors.Methods:A total of 427 patients with spinal metastatic tumors from January 2014 to January 2022 in the Second Affiliated Hospital of Zhejiang University School of Medicine were retrospectively analyzed. There were 252 males and 175 females, with an average age of 59±12 years (range, 15-87 years). All patients underwent separation surgery. Based on the chest CT within 1 month after surgery, the volume of pleural effusion was measured individually by reconstruction software. Pleural effusion was defined as small volume (0-500 ml), moderate volume (500-1 000 ml), and large volume (above 1 000 ml). Baseline data and perioperative clinical outcomes were compared between the groups, and indicators with statistically significant differences were included in a binary logistic regression analysis to determine the independent risk factors for the development of pleural effusion after isolation of spinal metastatic cancer. Receiver operating characteristic (ROC) curves were conducted to calculate the area under the curve (AUC) for each independent risk factor.Results:All patients successfully completed the operation. Among the 427 patients, there were 35 cases of large pleural effusion, 42 cases of moderate pleural effusion, and 350 cases of small pleural effusion. There were significant differences in tumor size (χ 2=9.485, P=0.013), intraoperative blood loss ( Z=-2.503, P=0.011), blood transfusion ( Z=-2.983, P=0.003), preoperative total protein ( Z=2.681, P=0.007), preoperative albumin ( Z=1.720, P= 0.085), postoperative hemoglobin ( t=2.950, P=0.008), postoperative total protein ( Z=4.192, P<0.001), and postoperative albumin ( t=2.268, P=0.032) in the large pleural effusion group versus the small and moderate pleural effusion group. Logistic regression analysis showed that decreased preoperative albumin ( OR=0.89, P=0.045) and metastases located in the thoracic spine ( OR=4.01, P=0.039) were independent risk factors for the occurrence of large pleural effusion after separation surgery. The ROC curve showed that the AUC and 95% CI for preoperative albumin, lesion location, and the combined model were 0.637 (0.54, 0.74), 0.421 (0.36, 0.48), and 0.883 (0.81, 0.92). The combined predictive model showed good predictive value. Conclusion:The volume of pleural effusion can be measured individually and quantitatively based on chest CT. Decreased preoperative albumin and metastases located in the thoracic spine are independent risk factors for the occurrence of large pleural effusion after separation surgery. The combined prediction of the two factors has better predictive efficacy.

Objective:To investigate the surgical method and clinical effect of O-arm navigation mini-open burring for osteoid osteoma.Methods:Eighteen patients with osteoid osteoma were treated with O-arm guided grinding drill from June 2021 to May 2022, including 15 males and 3 females, the age was (18.4 ±10.9) years (range 2 to 44 years), and the course of disease ranged from 1 week to 3 years (mean 14.2 months). The lesions sites included 6 cases of proximal femur, 3 cases of distal femur, 4 cases of proximal tibia, 1 case of distal tibia, 2 cases of proximal fibula and 1 case of distal and proximal humerus. During the operation, the O-arm navigation was used to determine the location of the focus, the muscle and soft tissue was peeled off to the bone surface through a 1-4 cm small incision, the channel retractor was placed, and the burr was registered as a navigation recognition device to gradually remove the bone on the surface of the tumor nest, and the tumor nest was scraped with a curette for pathological examination; according to the navigation image, the focus was enlarged removed with burr and the grinding range was confirmed by the O-arm X-ray machine before the end of the operation. The patients were followed up for 6 to 15 months (mean 9.5 months). CT scans were performed before and after surgery for imaging comparison in order to figure out whether it had residual lesions or recurrence. The visual analogue score (VAS) of pain was used as a parameter for evaluating the clinical efficacy.Results:The operation time of 18 cases was 40-175 min, with an average of 89.3 min. The time required to establish navigation image was 18.0 ±4.1 min (range 13 ~ 22 min). The length of the incision was 2.7±1.1 cm (range 1-4 cm). All patients achieved complete curettage of the lesions, and osteoid osteoma was confirmed by pathology after operation. All the patients could move to the ground 24 hours after operation, and the pain was significantly relieved from 3 to 7 d after operation, and the pain almost disappeared 3 months after operation. The VAS score of 18 cases was 5.33±1.24 before surgery, 2.79±1.32 on the 3rd day, 1.86±1.21 on the 7th day, 0.86±0.93 on the 1st month, 0.33±0.48 on the 3rd month, and 0.09±0.29 on the 6th month after operation, and the difference was statistically significant ( F=58.50, P<0.001). There were no serious complications during and after operation, and the success rate of treatment (no recurrence of symptoms, no residual recurrence of imaging lesions, no serious complications after operation) was 100%. Conclusion:Treatment of osteoid osteoma with mini-open excision using burrs under the navigation of O-arm is a simple, safe, minimally invasive and efficient technique. Intraoperative precise positioning and the use of burr with navigation to remove a larger area than the tumor nest are the keys to successful treatment.