Objective:To explore the clinical characteristics of dislocation after resection and reconstruction of tumors involving pelvic area II, and to try to propose intraoperative and postoperative techniques to prevent its occurrence.Methods:From March 2011 to March 2021, 122 patients with resection and reconstruction involving pelvic area II were retrospectively analyzed. Among them, 17 had postoperative dislocation, 32 had pelvic area II, and 31 had pelvic area I+II. There were 40 cases in the pelvic area II+III, and 19 cases in the pelvic area I+II+III. There were 49 female patients and 73 male patients; the mean age was 47 years (9-73 years). The Musculoskeletal Tumor Society (MSTS) score of lower extremity patients after reduction was evaluated, and the clinical characteristics of dislocation, such as dislocation direction, dislocation time and reduction method, were counted and analyzed, and feasible prevention measures were analyzed based on the imaging characteristics after resection and reconstruction. dislocation method.Results:Among the 122 patients, there were 17 cases of dislocation, and the dislocation rate was 13.7%. Among them, 12 cases were anterior dislocation, accounting for 70.6% of anterior dislocation; 5 cases were posterior dislocation, and the proportion of posterior dislocation was 29.4%, difference (χ 2=4.52, P=0.033). There were 12 cases of dislocation within 3 months after operation, accounting for 70.6%; 1 case of dislocation occurred in 5 months after operation, and the other 4 cases of dislocation occurred for more than one year. The MSTS score of the dislocation patients after reduction was 56.1±15.6% (20%-80%). Combined with postoperative imaging examinations, the feasible methods for preventing dislocation include: The anteversion angle of the acetabular cup can be appropriately reduced (0°-10°); The acetabular cup can be appropriately shifted to the rear of the rotation center; Appropriately reducing the anteversion angle of the femoral neck prosthesis, the combination of the three can reduce the occurrence of femoral-acetabular prosthesis impingement; at the same time, the affected limb is controlled in a neutral position with strict nail shoes after surgery to avoid the occurrence of external rotation. Conclusion:The dislocation after tumor resection and reconstruction in pelvic area II is mostly anterior dislocation. Postoperative CT scan of the pelvis shows that the space between the neck of the femoral stem prosthesis and the lower edge of the acetabulum is small, which is prone to impingement. If the anteversion angle of the acetabular cup is appropriately reduced, the acetabular prosthesis is appropriately displaced posteriorly, and the anteversion angle of the femoral neck is reduced by 5°, the possibility of femoral-acetabular impingement can be reduced, thereby reducing the risk of postoperative dislocation.

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.

Objective:To explore the risk factors of recurrence after resection of thigh soft tissue malignant tumors and the evaluation of the postoperative lower limb function.Methods:A total of 211 patients who underwent thigh soft tissue malignant tumor resection in the Department of Orthopaedics of the second affiliated Hospital of Medical College of Zhejiang University from May 2011 to May 2021 were retrospectively analyzed, including 117 males and 94 females, aged 53 (43, 65) years. There were 59 cases of atypical/well-differentiated liposarcoma, 30 cases of other types of liposarcoma, 33 cases of malignant fibrous histiocytoma, 19 cases of fibrosarcoma, 12 cases of rhabdomyosarcoma, 12 cases of leiomyosarcoma, 9 cases of synovial sarcoma, and 37 cases of others. The tumor involvement of muscle, bone, blood vessel, nerve tissue and intermuscular compartment, postoperative Musculoskeletal Tumor Society (MSTS) functional score and recurrence were recorded. The relationship between anatomical structure and postoperative recurrence was analyzed by Cox logistic regression to determine risk factors; the cumulative recurrence rate of different compartment groups (medial compartment, anterior compartment, and posterior compartment) were compared; The Box plot was used to compare the postoperative function of patients with resection of different anatomical structures (e.g., vastus lateralis, biceps femoris, femur, etc.).Results:A total of 34 out of 211 patients relapsed, with a recurrence rate of 16.1%. The recurrence time ranged from 2.6 months to 91.6 months after operation, with a median recurrence time of 37.0 (18.2, 52.8) months. Three independent risk factors were found to be associated with recurrence, namely: pathological grade [ HR=3.86, 95% CI(1.75, 8.51)], involvement of vastus intermedius [ HR=3.05, 95% CI(1.53, 6.06)], and involvement of vastus medialis [ HR=3.17, 95% CI(1.56, 6.41)]. The recurrence rate of patients with anterior chamber tumor resection was 35.3%, which was higher than that of patients without tumor resection (16.2%), and the difference was statistically significant ( P=0.020). There was no significant difference in recurrence rate between patients with medial chamber tumor resection and patients without tumor resection ( P>0.05). The recurrence rate of patients with posterior compartment tumor resection was 12.3%, which was lower than that of unresectable patients (37.6%), and the difference was statistically significant ( P=0.002).The postoperative MSTS score of 167 patients averaged 26±3.2 points (9-30 points). After intraoperative resection of part of the femur, vastus intermedius, vastus medialis, and rectus femoris, the patient's function was relatively poor [corresponding median MSTS score: 25 (23, 28), 26 (24 28), 26 (24,28), 26(24, 27)]. Conclusion:The risk factors for local recurrence after resection of thigh soft tissue malignant tumors include: pathological grade of the tumor, and whether the vastus intermedius or vastus medialis is involved. Anterior compartment tumors have a higher recurrence rate after surgery. If the tumor involves the above-mentioned anatomical structures, more attention should be paid to the risk of local recurrence after surgery.

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.