Use of a 3D-Printed Patient-Specific Surgical Jig and Ready-Made Total Sacral Endoprosthesis for Total Sacrectomy and Reconstruction

Objective. In the present study, the authors aimed to optimize the workflow of utilizing a 3D printing technique during surgical treatment for malignant sacral tumors, mainly on preparation of patient-specific surgical jigs and ready-made 3D-printed total sacral endoprosthesis. Methods. Three patients with a malignant sacral tumor received total sacrectomy with preoperative design of a patient-specific 3D-printed cutting jig and endoprosthetic reconstruction. Size of ready-made 3D-printed endoprosthesis was determined based on preoperative images, planned surgical margin, and size of the endoprosthesis. A patient-specific cutting jig was designed with a bilateral cutting slot matching the bilateral planes of the implant precisely. The tumor was removed en bloc through a single posterior approach only, being followed by reconstruction with ready-made total sacral endoprosthesis. Results. The mean time for preoperative design and manufacture of the surgical jig was 6.3 days. Surgical jigs were successfully used during surgery and facilitated the osteotomy. The mean operation time was 177 minutes (range 150-190 minutes). The mean blood loss was 3733 ml (range 3600-4000 ml). R0 resections were achieved in all the three cases proven by pathology. Evaluation of osteotomy accuracy was conducted by comparing preoperative plans and postoperative CT scans. The mean osteotomy deviation was 2.1 mm (range 0-4 mm), and mean angle deviation of osteotomy was 3.2° (range 0-10°). At a mean follow-up of 18.7 months, no local recurrence was observed. One patient had lung metastasis 15 months after surgery. Two patients were alive with no evidence of the disease. Conclusions. The patient-specific surgical jig and ready-made 3D-printed total sacral endoprosthesis can shorten the surgical preparation time preoperatively, facilitating accurate osteotomy and efficient reconstruction intraoperatively. The workflow seems to be feasible and practical.

DDRE-45. HIGH-THROUGHPUT SCREENING OF EPIGENETIC COMPOUNDS FOR THE TREATMENT OF CHORDOMA IDENTIFIES POTENTIAL NOVEL THERAPEUTICS

BACKGROUND Chordoma is a rare malignant tumor with few treatment options. While surgical resection is deemed the most effective treatment, the 5-year overall survival rate is 61% and 5-year recurrence free survival rate is approximately 50%. To date, no FDA approved pharmacotherapies exist for the treatment of chordoma, and adjuvant therapy remains highly debated. This necessitates the need for further research to provide clinicians with more options to treat this patient population. METHODS In this study, we conducted a high-throughput 139-compound epigenetic inhibitor screen against 12 chordoma patient-derived cell lines; 4 were resected at our institution and 8 were graciously donated by the Chordoma Foundation. RESULTS 8 tumors were located in the sacrum, 3 were located in the mobile spine, and 1 tumor was located in the clivus. 5 tumors were primary, 5 were recurrent, and 2 were metastatic. 6 tumors came from female patients and 6 tumors came from male patients. The top three most effect compounds across the cohort were the G9a inhibitor UNC0631 (cell viability = 64.5% +/-25.1SD; p=1.53x10-9), the KDM inhibitor JIB-04 (cell viability = 68.4% +/-27.2SD; p=9.81x10-8), and the G9a inhibitor BIX01294 (cell viability = 68.6% +/-27.9SD; p=1.27x10-7). No single compound significantly reduced viability in every tumor in the cohort, although the HDAC inhibitor HC Toxin significantly reduced viability in 9 tumors (cell viability = 69.7% +/-16.6SD; p=2.6x10-12). The most effective compound for sacral tumors was UNC0631 (viability = 68.6% +/-22.1SD; p=4x10-7), UNC0631 was also the most effective for spinal tumors (viability = 54.4% +/-32.1SD; p=2.72x10-3), and notably, no significant compounds were identified for the single clival tumor. CONCLUSIONS Based on our drug screen results, epigenetic inhibition, particularly methyltransferase inhibition, may be a promising therapeutic avenue for the treatment of chordomas.

Radiomics Models for the Preoperative Prediction of Pelvic and Sacral Tumor Types: A Single-Center Retrospective Study of 795 Cases

PurposeTo assess the performance of random forest (RF)-based radiomics approaches based on 3D computed tomography (CT) and clinical features to predict the types of pelvic and sacral tumors.Materials and MethodsA total of 795 patients with pathologically confirmed pelvic and sacral tumors were analyzed, including metastatic tumors (n = 181), chordomas (n = 85), giant cell tumors (n =120), chondrosarcoma (n = 127), osteosarcoma (n = 106), neurogenic tumors (n = 95), and Ewing’s sarcoma (n = 81). After semi-automatic segmentation, 1316 hand-crafted radiomics features of each patient were extracted. Four radiomics models (RMs) and four clinical-RMs were built to identify these seven types of tumors. The area under the receiver operating characteristic curve (AUC) and accuracy (ACC) were used to evaluate different models.ResultsIn total, 795 patients (432 males, 363 females; mean age of 42.1 ± 17.8 years) were consisted of 215 benign tumors and 580 malignant tumors. The sex, age, history of malignancy and tumor location had significant differences between benign and malignant tumors (P < 0.05). For the two-class models, clinical-RM2 (AUC = 0.928, ACC = 0.877) performed better than clinical-RM1 (AUC = 0.899, ACC = 0.854). For the three-class models, the proposed clinical-RM3 achieved AUCs between 0.923 (for chordoma) and 0.964 (for sarcoma), while the AUCs of the clinical-RM4 ranged from 0.799 (for osteosarcoma) to 0.869 (for chondrosarcoma) in the validation set.ConclusionsThe RF-based clinical-radiomics models provided high discriminatory performance in predicting pelvic and sacral tumor types, which could be used for clinical decision-making.

Modern approach to the treatment of sacrococcygeal chordomas

Chordomas of the sacrococcygeal region account for more than 50 % of all sacral tumors. These malignant neoplasms grow slowly and are asymptomatic for a long time. As a result, chordomas often reach large sizes and affect the neurovascular structures of the sacrum and pelvic organs. The use ofen-bloc resection allows to increase survival rates and reduce the risk of progression. However, this method of chord treatment is difficult for surgeons and in most cases, after surgery, the quality of life of patients decreases. The improvement of imaging methods, the success of oncological orthopedics and radiation therapy allow performing radical organ-preserving operations. In this article, we will consider the modern concept of treatment with a sacrococcygeal chord.

Sacroplasty Augmentation of Instrumented Pelvic Reconstruction After High Sacrectomy: A Technical Case Report

BACKGROUND AND IMPORTANCE En bloc resection of sacral tumors is the most effective treatment to help prevent recurrence. Sacrectomy, however, can be destabilizing, depending on the extent of resection. Various surgical techniques for improving stability and enabling early ambulation have been proposed. CLINICAL PRESENTATION Here, we report a case in which we use PMMA (poly[methyl methacrylate]) to augment pelvic instrumentation to improve mechanical stability after sacrectomy for en bloc resection of a solitary fibrous tumor. CONCLUSION We highlight the use of sacroplasty augmentation of pelvic ring reconstruction to provide biomechanical stability without the need for fusion of any mobile spine segments, which allowed for early patient ambulation and no appreciable loss of range of motion or mobility.

Demystifying Sacral Masses: A Pictorial Review

The sacrum is a triangular shaped bone made up of five fused vertebral bodies. It is composed of bone, cartilage, marrow elements as well as notochord remnants and is a common site for both benign and malignant (primary and secondary) tumors. Familiarity with the imaging features and clinical presentations of sacral bone tumors could be helpful in narrowing the differential diagnosis. Magnetic resonance imaging and computed tomography are the preferred imaging modalities for evaluating sacral masses. This pictorial review will highlight imaging features of common sacral tumors with pathologic correlation. Additionally, this article will review some critical principles and helpful tips to successfully biopsy these lesions.