Revision surgery for periprosthetic fracture of distal femur after endoprosthetic replacement of knee joint following resection of osteosarcoma.

Purpose: Periprosthetic fracture (PPF) is one of the severe complications in patients with osteosarcoma and carries the risk of limb loss. This study describes the characteristics, treatment strategies, and outcomes of this complication. Methods: Patients were consecutively included who were treated at our institution between 2016 and 2020 with a PPF of distal femur. The treatment strategies included two types: 1) open reduction and internal fixation with plates and screws and 2) replacement with long-stem endoprosthesis and reinforcement with wire rope if necessary. Results: A total of 11 patients (mean age 12.2 years (9-14)) were included, and the mean follow-up period was 36.5 (21-54) months. Most fractures were caused by direct or indirect trauma (n = 8), and others (n = 3) underwent PPF without obvious cause. The first type of treatment was performed on four patients, and the second type was performed on seven patients. The mean Musculoskeletal Tumor Society (MSTS) score was 20 (17-23). All patients recovered from the complication, and limb preservation could be achieved. Conclusion: PPF is a big challenge for musculoskeletal oncologists, particularly in younger patients. Additionally, PPF poses a challenge for orthopedic surgeons, as limb preservation should be an important goal. Hence, internal fixation with plates and endoprosthetic replacement are optional treatment strategies based on fracture type and patient needs.

HMGB1 Positive Feedback Loop Between Cancer Cells and Tumor-Associated Macrophages Promotes Osteosarcoma Migration and Invasion.

Numerous studies have demonstrated the key roles of tumor-associated macrophages (TAMs) in osteosarcoma metastasis. Higher levels of high mobility group box 1 (HMGB1) promote osteosarcoma progression. However, whether HMGB1 is involved in the polarization of M2 macrophages into M1 macrophages in osteosarcoma remains largely unknown. Here, HMGB1 and CD206 mRNA expression levels were measured by a quantitative reverse transcription-polymerase chain reaction in osteosarcoma tissues and cells. HMGB1 and receptor for advanced glycation end products (RAGE) protein expression levels were measured by western blotting. Osteosarcoma migration was measured using transwell and wound-healing assays, while a transwell assay determined osteosarcoma invasion. Macrophage subtypes were detected using flow cytometry. HMGB1 expression levels were aberrantly enhanced in osteosarcoma tissues compared with normal tissues and were positively correlated with AJCC III and IV stages, lymph node metastasis, and distant metastasis. Silencing HMGB1 inhibited the migration, invasion, and epithelial-mesenchymal transition (EMT) of osteosarcoma cells. Furthermore, reduced HMGB1 expression levels in conditioned media derived from osteosarcoma cells induced the polarization of M2 TAMs to M1 TAMs. In addition, silencing HMGB1 inhibited the liver and lung metastasis of tumors and reduced the expression levels of HMGB1, CD163, and CD206 in vivo. HMGB1 was found to regulate macrophage polarization through RAGE. Polarized M2 macrophages induced osteosarcoma migration and invasion, activating HMGB1 expression in osteosarcoma cells to form a positive feedback loop. In conclusion, HMGB1 and M2 macrophages enhanced osteosarcoma migration, invasion, and EMT through positive feedback regulation. These findings reveal the significance of tumor cell and TAM interactions in the metastatic microenvironment.

En bloc resection of huge primary tumors with epidural involvement in the mobile spine using the "rotation-reversion" technique: Feasibility, safety, and clinical outcome of 11 cases.

Background: En bloc resection of spinal tumors provides better local control and survival outcomes than intralesional resection. Safe margins during en bloc resection of primary spinal tumors with epidural involvement are required for improved outcomes. The present study describes a "rotation-reversion" technique that has been used for en bloc resection of huge primary tumors in the mobile spine with epidural involvement and reported the clinical outcomes in these patients. Methods: All patients with primary spinal tumors who were treated with the rotation-reversion technique at our institution between 2015 and 2021 were evaluated retrospectively. Of the patients identified, those with both huge extraosseous soft-tissue masses and epidural involvement were selected for a case review. Clinical and radiological characteristics, pathologic findings, operative procedures, complications, and oncological and functional outcomes of these patients were reviewed. Results: Of the 86 patients identified with primary spinal tumors who underwent en bloc resection using the rotation-reversion technique between 2015 and 2021, 11 had huge extraosseous soft-tissue masses with epidural involvement in the mobile spine. The average maximum size of these 11 tumors was 8.1 × 7.5 × 9.7 cm. Median follow-up time was 28.1 months, mean operation time was 849.1 min (range 465-1,340 min), and mean blood loss was 6,972.7 ml (range 2,500-17,700 ml), with 10 (91%) of the 11 patients experiencing perioperative complications. The negative margin rate was 91%, with only one patient (9%) experiencing local recurrence. Ten patients were able to walk normally or with a crutch at the last follow-up, whereas one was completely paralyzed preoperatively. Conclusion: The rotation-reversion technique is an effective procedure for the en bloc resection of huge primary spinal tumors, with the extension of invasion in selected patients including not only the vertebral body but also the pedicle and part of the posterior arch.

Image-guided percutaneous biopsy and pathological diagnosis in atypical tuberculous spondylitis: a case series and clinical outcomes.

Background: Tuberculous spondylitis can be difficult to distinguish from alternative spinal pathologies such as malignancy, particularly if the imaging features are not typical. Biopsy and histopathological analysis are facilitative to the early and accurate diagnosis of atypical tuberculous spondylitis and the clinical management. The purpose of this study is to describe some of the atypical imaging features of tuberculous spondylitis diagnosed by image-guided percutaneous biopsy, as well as associated treatment outcomes. Methods: We performed a retrospective analysis of all patients diagnosed with tuberculous spondylitis after image-guided percutaneous biopsy at The Third Affiliated Hospital of Southern Medical University between 2013 and 2020. Of the patients identified, those with atypical imaging features were selected for case review. All patients were given anti-tuberculous medication treatment with or without surgery. The imaging features, histological and microbiological results, and clinical presentations and outcomes were evaluated. Neurological function was evaluated according to the Frankel grading system. The clinical outcomes were evaluated by Visual Analogic Scale (VAS) scores for pain, imaging [X-ray, computed tomography (CT), and magnetic resonance imaging (MRI)] results, and laboratory examinations. Comparison of VAS scores was made by Student t-test. Results: Of the 102 patients identified with tuberculous spondylitis between 2013 and 2020, eight patients (two females and six males) with a mean age of 41.6 years (range, 18-61 years) demonstrated atypical imaging findings, including central vertebral body lesion, multiple skip vertebral lesions, extradural mass lesion and anterior subperiosteal lesion. All eight patients received anti-tuberculous medication treatment, and six underwent surgery. One patient developed a pleural effusion after debridement of the thoracic lesion. The mean follow-up period was 16.2 months (6-37 months). The VAS scores before treatment and at the final follow-up showed significant differences (7.25±1.49 and 0.0±0.0, respectively, P<0.01). Improved neurological function were observed in all patients. Solid fusion and osteogenic osteosclerosis were observed at the final follow-up, and no recurrence was observed in any cases. Conclusions: All eight patients had a good prognosis. Image-guided biopsy and histopathological analysis are helpful for the early diagnosis of tuberculous spondylitis, especially when imaging features are not typical for this condition.

A Comprehensive Understanding of the Genomic Bone Tumor Landscape: A Multicenter Prospective Study.

Complexity and heterogeneity increases the difficulty of diagnosis and treatment of bone tumors. We aimed to identify the mutational characterization and potential biomarkers of bone tumors. In this study, a total of 357 bone tumor patients were recruited and the next generation sequencing (NGS)-based YuanSu450 panel, that includes both DNA and RNA sequencing, was performed for genomic alteration identification. The most common mutated genes in bone tumors included TP53, NCOR1, VEGFA, RB1, CCND3, CDKN2A, GID4, CCNE1, TERT, and MAP2K4. The amplification of genes such as NCOR1, VEGFA, and CCND3 mainly occurred in osteosarcoma. Germline mutation analysis reveal a high frequency of HRD related mutations (46.4%, 13/28) in this cohort. With the assistance of RNA sequencing, 16.8% (19/113) gene fusions were independently detected in 20% (16/79) of patients. Nearly 34.2% of patients harbored actionable targeted mutations, of which the most common mutation is CDKN2A deletion. The different mutational characterizations between juvenile patients and adult patients indicated the potential effect of age in bone tumor treatment. According to the genomic alterations, the diagnosis of 26 (7.28%) bone tumors were corrected. The most easily misdiagnosed bone tumor included malignant giant cell tumors of bone (2.8%, 10/357) and fibrous dysplasia of bone (1.7%, 6/357). Meanwhile, we found that the mutations of MUC16 may be a potential biomarker for the diagnosis of mesenchymal chondrosarcomas. Our results indicated that RNA sequencing effectively complements DNA sequencing and increased the detection rate of gene fusions, supporting that NGS technology can effectively assist the diagnosis of bone tumors.

Application of a novel porous tantalum implant in rabbit anterior lumbar spine fusion model: in vitro and in vivo experiments.

BACKGROUND: Some porous materials have been developed to enhance biologic fusion of the implants to bone in spine fusion surgeries. However, there are several inherent limitations. In this study, a novel biomedical porous tantalum was applied to in vitro and in vivo experiments to test its biocompatibility and osteocompatibility. METHODS: Bone marrow-derived mesenchymal stem cells (BMSCs) were cultured on porous tantalum implant. Scanning electron microscope (SEM) and Cell Counting Kit-8 assay were used to evaluate the cell toxicity and biocompatibility. Twenty-four rabbits were performed discectomy only (control group), discectomy with autologous bone implanted (autograft group), and discectomy with porous tantalum implanted (tantalum group) at 3 levels: L3-L4, L4-L5, and L5-L6 in random order. All the 24 rabbits were randomly sacrificed at the different post-operative times (2, 4, 6, and 12 months; n = 6 at each time point). Histologic examination and micro-computed tomography scans were done to evaluate the fusion process. Comparison of fusion index scores between groups was analyzed using one-way analysis of variance. Other comparisons of numerical variables between groups were made by Student t test. RESULTS: All rabbits survived and recovered without any symptoms of nerve injury. Radiographic fusion index scores at 12 months post-operatively between autograft and tantalum groups showed no significant difference (2.89 ±â€Š0.32 vs. 2.83 ±â€Š0.38, F = 244.60, P = 0.709). Cell Counting Kit-8 assay showed no significant difference of absorbance values between the leaching liquor group and control group (1.25 ±â€Š0.06 vs. 1.23 ±â€Š0.04, t = -0.644, P = 0.545), which indicated the BMSC proliferation without toxicity. SEM images showed that these cells had irregular shapes with long spindles adhered to the surface of tantalum implant. No implant degradation, wear debris, or osteolysis was observed. Histologic results showed solid fusion in the porous tantalum and autologous bone implanted intervertebral spaces. CONCLUSION: This novel porous tantalum implant showed a good biocompatibility and osteocompatibility, which could be a valid biomaterial for interbody fusion cages.

Huge myxoid chondrosarcoma expanded into the thoracic cavity with spinal involvement.

PURPOSE: En bloc resection is the treatment of choice of myxoid chondrosarcoma. These tumors can produce huge masses. Anatomical constraints limit the possibility to perform en bloc resection in the spine. METHODS: A very huge myxoid chondrosarcoma (14.2 × 10.8 × 11.4 cm) arising from T2 to T5 and invading the whole higher left pleural cavity was observed. Surgical planning according to WBB staging system was performed. RESULTS: The tumor was successfully submitted to en bloc resection achieving a tumor-free margin as demonstrated by the pathologist's report. CONCLUSIONS: A careful planning and a multidisciplinary collaboration make possible to perform en bloc resection even in apparently impossible cases.

MicroRNA 628 suppresses migration and invasion of breast cancer stem cells through targeting SOS1.

PURPOSE: The purpose of this study is to evaluate the effects of miR-628 on migration and invasion of breast cancer stem cells (CSCs), which are essential for tumor recurrence and metastasis. MATERIALS AND METHODS: Quantitative reverse transcription-polymerase chain reaction was used to determine the expression of microRNAs and mRNAs. A subpopulation of CD44+/CD24- breast CSCs were sorted by flow cytometry. Transwell assays were used to evaluate cell migration and invasion. Luciferase reporter assays were performed to verify whether miR-628 targeted SOS Ras/Rac guanine nucleotide exchange factor 1 (SOS1). pcDNA3.1(+)-SOS1 was constructed for overexpressing SOS1 after transfection. RESULTS: Compared with primary breast cancer cells, bone metastatic breast cancer cells showed significant downregulation of miR-628. The CD44+/CD24- breast CSC subpopulations in MDA-MB-231 and MCF-7 cell lines were analyzed and sorted. Transfection with an miR-628 mimic significantly suppressed the migration and invasion of these breast CSCs by targeting SOS1, which plays an essential role in epithelial-to-mesenchymal transition. Overexpression of SOS1 rescued miR-628-mediated migration and invasion by upregulating Snail and vimentin, and downregulating E-cadherin. CONCLUSION: miR-628 suppressed migration and invasion of breast CSCs of MDA-MB-231 and MCF-7 cells by directly targeting SOS1. Enhancement of miR-628 expression might be an effective strategy for managing breast cancer metastasis.