Prognostic Analysis of Spinal Metastasis Secondary to Lung Cancer after Surgeries: A Unicentric, Large-Cohort, Retrospective Study

The Impact of Adjunct Medical Therapy on Survival after Spine Metastasis: A Systematic Review and Pooled Data Analysis

Targeted therapy has greatly improved the outlook for patients with spinal metastatic cancers. Scoring systems like the Tokuhashi or Tomita scores are commonly used to predict prognosis and inform surgical decisions, but they are outdated and fail to consider recent advancements. We aimed to investigate the current state of the literature and treatment options pertaining to advancements in targeted therapy compared to other forms of medical management for metastatic spinal tumors. This study represents the first comprehensive systematic review that encompasses the most common primary cancers that metastasize to the spine and evaluates the median overall survival (mOS) across five different medical treatment modalities as well as surgical intervention. Additionally, our study analyzes the tumor receptor status in conjunction with these treatments. A PubMed search was conducted, and according to the PRISMA guidelines, 28 articles out of 1834 met the inclusion criteria. The pooled data analysis highlighted the superior efficacy of targeted therapy, evidenced by a significant improvement in the mOS and lower hazard ratios in patients with lung and breast cancers who received targeted therapy compared to those who did not. Our study provides valuable insights into the recent advancements in the medical management of metastatic spinal tumors. Future indications include incorporating this literature into personalized treatment approaches for metastatic spinal tumors.

Biomechanical effects of transverse connectors on total en bloc spondylectomy of the lumbar spine: a finite element analysis

BACKGROUND

The influence of total en bloc spondylectomy (TES) on spinal stability is substantial, necessitating strong fixation to restore spinal stability. The transverse connector (TC) serves as a posterior spinal instrumentation that connects the left and right sides of the pedicle screw-rod system. Several studies have highlighted the potential of a TC in enhancing the stability of the fixed segments. However, contradictory results have suggested that a TC not only fails to improve the stability of the fixed segments but also might promote stress associated with internal fixation. To date, there is a lack of previous research investigating the biomechanical effects of a TC on TES. This study aimed to investigate the biomechanical effects of a TC on internal fixation during TES of the lumbar (L) spine.

METHODS

A single-segment (L3 segment) TES was simulated using a comprehensive L spine finite element model. Five models were constructed based on the various positions of the TC, namely the intact model (L1-sacrum), the TES model without a TC, the TES model with a TC at L1-2, the TES model with a TC at L2-4, and the TES model with a TC at L4-5. Mechanical analysis of these distinct models was conducted using the Abaqus software to assess the variations in the biomechanics of the pedicle screw-rod system, titanium cage, and adjacent endplates.

RESULTS

The stability of the surgical segments was found to be satisfactory across all models. Compared with the complete model, the internal fixation device exhibited the greatest constraint on overextension (95.2-95.6%), while showing the least limitation on left/right rotation (53.62-55.64%). The application of the TC had minimal effect on the stability of the fixed segments, resulting in a maximum reduction in segment mobility of 0.11° and a variation range of 3.29%. Regardless of the use of a TC, no significant changes in stress were observed for the titanium cage. In the model without the TC, the maximum von Mises stress (VMS) for the pedicle screw-rod system reached 136.9 MPa during anterior flexion. Upon the addition of a TC, the maximum VMS of the pedicle screw-rod system increased to varying degrees. The highest recorded VMS was 459.3 MPa, indicating a stress increase of 335.5%. Following the TC implantation, the stress on the adjacent endplate exhibited a partial reduction, with the maximum stress reduced by 27.6%.

CONCLUSION

The use of a TC in TES does not improve the stability of the fixed segments and instead might result in increased stress concentration within the internal fixation devices. Based on these findings, the routine utilisation of TC in TES is deemed unnecessary.