Surgical Treatment of Primary Osteosarcoma of the Sacrum: A Case Series of 26 Patients

Complex geometry and integrated macro-porosity: Clinical applications of electron beam melting to fabricate bespoke bone-anchored implants

The last decade has witnessed rapid advancements in manufacturing technologies for biomedical implants. Additive manufacturing (or 3D printing) has broken down major barriers in the way of producing complex 3D geometries. Electron beam melting (EBM) is one such 3D printing process applicable to metals and alloys. EBM offers build rates up to two orders of magnitude greater than comparable laser-based technologies and a high vacuum environment to prevent accumulation of trace elements. These features make EBM particularly advantageous for materials susceptible to spontaneous oxidation and nitrogen pick-up when exposed to air (e.g., titanium and titanium-based alloys). For skeletal reconstruction(s), anatomical mimickry and integrated macro-porous architecture to facilitate bone ingrowth are undoubtedly the key features of EBM manufactured implants. Using finite element modelling of physiological loading conditions, the design of a prosthesis may be further personalised. This review looks at the many unique clinical applications of EBM in skeletal repair and the ground-breaking innovations in prosthetic rehabilitation. From a simple acetabular cup to the fifth toe, from the hand-wrist complex to the shoulder, and from vertebral replacement to cranio-maxillofacial reconstruction, EBM has experienced it all. While sternocostal reconstructions might be rare, the repair of long bones using EBM manufactured implants is becoming exceedingly frequent. Despite the various merits, several challenges remain yet untackled. Nevertheless, with the capability to produce osseointegrating implants of any conceivable shape/size, and permissive of bone ingrowth and functional loading, EBM can pave the way for numerous fascinating and novel applications in skeletal repair, regeneration, and rehabilitation. STATEMENT OF SIGNIFICANCE: Electron beam melting (EBM) offers unparalleled possibilities in producing contaminant-free, complex and intricate geometries from alloys of biomedical interest, including Ti6Al4V and CoCr. We review the diverse range of clinical applications of EBM in skeletal repair, both as mass produced off-the-shelf implants and personalised, patient-specific prostheses. From replacing large volumes of disease-affected bone to complex, multi-material reconstructions, almost every part of the human skeleton has been replaced with an EBM manufactured analog to achieve macroscopic anatomical-mimickry. However, various questions regarding long-term performance of patient-specific implants remain unaddressed. Directions for further development include designing personalised implants and prostheses based on simulated loading conditions and accounting for trabecular bone microstructure with respect to physiological factors such as patient's age and disease status.

Association between intraoperative fluid overload and postoperative debridement in major sacrum tumor resection: A propensity score matching study

Intra-aortic balloon occlusion (IABO) is used to reduce intraoperative bleeding and facilitate successful sacrum tumor resection. Up to 20% of patients experience postoperative wound healing problems, but the risk factors related to this complication have not been clearly defined. The anesthetic database of Peking University People's Hospital, Beijing, China, was searched for all patients (aged 14-70 years old) who underwent sacrum tumor surgery with the application of IABO from 2014 to 2017. Data from 278 patients with an aortic occlusion duration of 72 ± 33 minutes were collected. Fifty-six patients required postoperative debridement because of wound infection. The independent risk factor identified by logistic regression was fluid excess (calculated as volume infused minus blood loss and urine output divided by body weight [kg]), and decision tree analysis revealed that the cutoff point for fluid excess was 38.5 mL/kg. Then patients were then divided into high fluid excess group (fluid excess > 38.5 mL/kg) and low fluid excess group (fluid excess ≤ 38.5 mL/kg) and 91 pairs of patients were generated through propensity score matching (PSM). Fluid excess was significantly higher in the high fluid excess group (46 vs 30 mL/kg, P < .001), and more patients required postoperative debridement than in the low fluid excess group (24 (26.3%) vs 12 (13.1%), P < .001). In this retrospective PSM study on sacrum tumor resection, fluid overload was related to postoperative debridement and further studies are needed to improve the clinical prognosis.

Primary Tumors of the Sacrum: Imaging Findings

The diagnosis of sacral neoplasms is often delayed because they tend to remain clinically silent for a long time. Imaging is useful at all stages of managing sacral bone tumors: from the detection of the neoplasm to the long-term follow-up. Radiographs are recommended as the modality of choice to begin the imaging workup of a patient with known or suspected sacral pathology. More sensitive examinations such as computerized tomography (CT), magnetic resonance (MRI), or scintigraphy are often necessary. The morphological features of the lesions on CT and MRI help to orientate the diagnosis. Although some imaging characteristics are helpful to limit the differential diagnosis, an imaging-guided biopsy is often ultimately required to establish a specific diagnosis. Imaging is of paramount importance even in the long-term follow-up in order to assess any residual tumor when surgical resection is incomplete, to assess the efficacy of adjuvant chemotherapy and radiotherapy, and to detect recurrence.

Total sacrectomy with a combined antero-posterior surgical approach for malignant sacral tumours

Purpose

To investigate the indications, approaches, resection methods, and complications of total sacrectomy with a combined antero-posterior approach for malignant sacral tumours.

Methods

Fourteen cases of primary malignant sacral tumours treated with total sacrectomy between January 2012 and 2018 were retrospectively analysed. All patients presented with pre-operative lumbosacral pain or constipation. A combined antero-posterior approach was used for tumour resection, and the spinal pedicle screw rod system was used to achieve ilio-lumbar stability. The visual analogue scale (VAS) and Musculoskeletal Tumor Society (MSTS) scores were used to assess pain and lower limb function, respectively. The mean operative time and intra-operative blood loss were 6.54 hours and 2935 mL, respectively. The mean follow-up period was 62 months.

Results

None of the patients died peri-operatively. At the last follow-up, ten patients were continuously disease-free, three were alive with disease, and one died of disease from lung metastasis. Tumour recurrence occurred in three patients. The MSTS scores ranged from 6 to 28 (20.00–93.33%, 6/30–28/30) with an average of 20 (66.67%, 20/30). Seven patients could walk independently in public, five could only walk at home using a walking aid, and two could only lie down and stand for a short time. Thirteen patients developed post-operative complications such as skin necrosis, screw loosening, connecting rod fracture, neuropathic pain, sciatic nerve injury, dysuria, and urinary incontinence.

Conclusion

Total sacrectomy can effectively treat malignant sacral tumours with good resection boundaries and prognosis. However, the high incidence of post-operative complications may impact post-operative neurological function.

LINC01278 is Highly Expressed in Osteosarcoma and Participates in the Development of Tumors by Mediating the miR-134-5p/KRAS Axis

Purpose

There is increasing evidence that non-coding RNAs (ncRNAs), including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), produce a critical regulatory effect on osteosarcoma (OS). LINC01278, as a newly discovered lncRNA, is found to be highly expressed in OS, but its related mechanism remains unclear. This research, therefore, is designed to study the mechanism of LINC01278 in OS and to find potential targets for clinical use.

Methods

qRT-PCR was applied to determine the relative expression of LINC01278 and analyze its diagnostic value in OS. CCK-8, Transwell and flow cytometry were utilized for the determination of cell proliferation, migration/invasion, and apoptosis. RIP and RNA pull-down experiments were used to verify the targeted binding effect of miR-134-5p and LINC01278. The relationship between miR-134-5p and LINC01278 or KRAS was analyzed using dual luciferase reporter gene. The effects of LINC01278 on tumor growth in nude mice was analyzed by in vivo experiment.

Results

qRT-PCR showed that LINC01278 increased in OS tissues and serum, indicating poor prognosis. In addition, LINC01278 was also of high value for OS diagnosis. Functional experiments showed that LINC01278 inhibited KRAS-mediated OS cell proliferation and metastasis through miR-134-5p. Finally, the results of an in vivo animal model indicated that LINC01278 promoted OS growth.

Conclusion

LINC01278 is expressed highly in OS, and patients with high LINC01278 expression have poor prognosis. Moreover, LINC01278 can suppress the proliferation and apoptosis of OS cells through mediating miR-134-5p/KRAS axis, which is expected to become a potential therapeutic target for OS.

Cyclin E1 is a prognostic biomarker and potential therapeutic target in osteosarcoma

While amplified expressed cyclin E1 is a well-known tumorigenic factor and prognostic biomarker in several malignancies, its prognostic predictive potential and function in osteosarcoma is poorly understood. Here we reveal discrete expression pattern, correlation to clinicopathological characteristics and prognosis and overall function of cyclin E1 in osteosarcoma. Sixty-nine osteosarcoma patient tumor specimens were enrolled to construct a tissue microarray to evaluate cyclin E1 expression through immunohistochemical staining. Cyclin E1 expression in osteosarcoma cell lines and fresh tissues was assessed by Western blot. Cyclin E1 gene expression was evaluated using RNA sequencing data acquired from the public database. We correlated staining intensity to clinical characteristics. Cyclin E1 small interfering RNA was used to determine the effect of cyclin E1 silencing on osteosarcoma cell proliferation and chemotherapeutic sensitivity. Sixty-one percent of the osteosarcoma patient specimens in the tissue microarray had high cyclin E1 expression. Cyclin E1 gene was significantly highly expressed in osteosarcoma tissues and cell lines compared to normal tissues. The expression of cyclin E1 positively correlated with disease status, and inversely correlated to prognosis and response to neoadjuvant chemotherapy. The expression of cyclin E1 was an independent prognostic factor for osteosarcoma patients. In addition, silencing cyclin E1 expression in osteosarcoma cells significantly inhibited cell proliferation and increased sensitivity to chemotherapeutics. We conclude that cyclin E1 is overexpressed in osteosarcoma and is a promising biomarker for prognosis and chemotherapeutic response. We confirm aberrant cyclin E1 expression is a potent therapeutic target in osteosarcoma, and its selective inhibition is a rational treatment strategy for osteosarcoma.

Assessment of patient experiences following total sacrectomy for primary malignant sacral tumors: A qualitative study

BACKGROUND AND OBJECTIVES

Few reports have investigated patient experiences following total en bloc sacrectomy. The aims of this study were to obtain a deeper understanding of patients' personal experiences, needs, and satisfaction with the treatment to reveal areas in which perioperative and long-term patient care can be improved.

METHODS

A qualitative design was applied to examine patient experiences and supportive care needs. Patients treated between 2007 and 2017 were identified from our institutional database.

RESULTS

A total of 28 survivors were interviewed (13 females, age 13-75 years). Eight themes were identified: the effect of surgery on patients' (a) daily lives, (b) social activities, (c) work or school activities, (d) and family lives; (e) acceptance of ostomy surgery; (f) need for guidance regarding long-term rehabilitation; (g) satisfaction with the medical services provided in the hospital; and (h) satisfaction with the treatment outcomes.

CONCLUSION

Total en bloc sacrectomy can yield satisfactory oncological outcomes; however, the procedure is a life-changing event for patients and their families. Physicians must provide long-term support and guidance after surgery to enable patients to fully understand and cope with the changes in their lives.

Ras-ERK1/2 Signaling Promotes The Development Of Osteosarcoma By Regulating H2BK12ac Through CBP

Background

H2BK12ac is an important histone acetylation pattern of H2B, which has been reported in several cancers. However, whether H2BK12ac joins in Ras-ERK1/2 activation-induced osteosarcoma (OS) cell behaviors remain unclear. The study explored this peradventure and revealed the underlying mechanism.

Methods

MG-63 cells were transfected with pEGFP-N1, pEGFP-Ras^WT and pEGFP-K-Ras^G12V/T35S, H2BK12ac and ERK1/2 expression levels were analyzed by Western blot. Effects of H2BK12ac on cell viability, migration, colony formation and cell cycle were investigated by MTT, Transwell, soft-agar colony formation and flow cytometry assays. RT-qPCR and ChIP were performed to study the effect of H2BK12ac and CBP on ERK1/2-downstream gene transcriptions.

Results

H2BK12ac was specifically down-regulated by Ras-ERK1/2 activation in MG-63 cells. Down-regulated H2BK12ac participated in regulating cell proliferation and migration of MG-63 cells, meanwhile, affected the transcription of ERK1/2-downstream genes. Additionally, silence of HDAC1 up-regulated H2BK12ac expression, and inhibited the promoting effect of Ras-ERK1/2 on MG-63 cells' proliferation, migration and RNA expression levels of ERK1/2-downstream genes. Further, the degradation of CBP mediated by MDM2 was discovered to be linked to Ras-ERK1/2 activation-induced H2BK12ac down-regulation.

Conclusion

These findings from the study demonstrated that Ras-ERK1/2 signaling could promote the development of OS via regulating H2BK12ac through MDM2-mediated CBP degradation.

Factors Associated With Spinopelvic Fixation Mechanical Failure After Total Sacrectomy

STUDY DESIGN

We retrospectively analyzed factors associated with spinopelvic mechanical failure after total sacrectomy.

OBJECTIVE

To find the rate and type of mechanical fixation failure after total sacrectomy and to identify the associated risk factors.

SUMMARY OF BACKGROUND DATA

Although rigid fixation has been achieved, mechanical failure is sometimes encountered in reconstruction after total sacrectomy. The incidence and factors associated with spinopelvic fixation mechanical failure after total sacrectomy are still not clear.

METHODS

The study comprised 63 patients who underwent spinopelvic reconstruction after total sacrectomy. The potential risk factors for fixation mechanical failure after total sacrectomy were evaluated, which included age, sex, body mass index, type of tumor (benign or malignant), and adjuvant treatment received (e.g., chemotherapy, radiation therapy). The surgery-related factors included the classification of tumor resection (en bloc or piecemeal resection) and the type of iliosacral resection. Adoption of anterior spinal column fixation (ASCF), posterior pelvic ring fixation (PPRF), four-rod technique (FRT) of spinopelvic fixation (SPF), and structural or morselized bone grafting after total sacrectomy in patients were considered reconstruction-related factors. Cox regression models were used to analyze associations between postoperative fixation failure and risk factors for all models.

RESULTS

Postoperative fixation mechanical failure occurred in 25% of patients (16/63) who underwent total sacrectomy. Univariate analysis showed that the factors associated with spinopelvic fixation mechanical failure after total sacrectomy were the non-adoption of FRT of SPF and ASCF, the adoption of Type II sacroiliac resection, and female sex, whereas multivariate analysis demonstrated similar results, except for the adoption of Type II sacroilliac resection.

CONCLUSION

FRT connection of SPF and ASCF should be adopted in reconstruction after total sacrectomy, especially in female patients.

LEVEL OF EVIDENCE

3.