Incidence and Risk Factors for Implant Failure in Spinal Metastasis Surgery

Finite element investigation of the influence of a new transpedicular vertebral implant positioning on biomechanical responses of the spine segment

The optimal positioning of an implant into a living organ such as femurs and vertebra is still an open problem. In particular, vertebral implant position has a significant impact on the results on spine behaviour after treatment in terms of stiffness, range of motion (ROM), wear, loosening and failure. In the current work, a 3D finite element analysis was conducted to investigate the positioning parameters of a novel transpedicular implant (V-STRUT©, Hyprevention, France) in terms of placement of the implant in the treated vertebra. The implant was designed in order to strength osteoporotic vertebral body and the related spine segment under compressive load. The effects of the axial and sagittal positions of the implant in the treated vertebra was investigated in terms of stress and stiffness variations. A 3D finite element model of an osteoporotic spine segment was built based on a Computed Tomography (CT) scan of an osteoporotic female (69 yo). The model is composed of T12, L1 and L2 vertebrae and corresponding intervertebral discs and ligaments. The bone tissue was modeled as a heterogeneous material with properties assigned based on the grey scale levels. The intervertebral discs were modeled using two regions describing the annulus and the nucleus and linear beam elements with specific stiffness each were used representing each ligament. The simulations indicated that the sagittal position (distance d) plays a role on the stress distribution. The closer the implant to the interior wall the lower the stress applied to the spine segment. Nevertheless, the axial plane position (distance h) have limited effects on the stress applied to the bone with a higher stress applied to the device (subjected to a higher bending load). These results can have direct clinical implications when dealing with the optimal placement of the implant. It is also possible to select a particular position in order to assign a given (target) stiffness for a patient.

Early fusion outcome after surgical treatment of single-level and multi-level pyogenic spondylodiscitis: experience at a level 1 center for spinal surgery-a single center cohort study

STUDY DESIGN

Retrospective single center cohort study.

PURPOSE

Spinal instrumentation in combination with antibiotic therapy is a treatment option for acute or chronic pyogenic spondylodiscitis (PSD). This study compares the early fusion outcome for multi-level and single-level PSD after urgent surgical treatment with interbody fusion in combination with fixation.

METHODS

This is a retrospective cohort study. Over a 10 year period at a single institution, all surgically treated patients received surgical debridement, fusion und fixation of the spine to treat PSD. Multi-level cases were either adjacent to each other on the spine or distant. Fusion rates were assessed at 3 and 12 months after surgery. We analyzed demographic data, ASA status, duration of surgery, location and length of spine affected, Charlson comorbidity index (CCI), and early complications.

RESULTS

A total of 172 patients were included. Of these, 114 patients suffered from single-level and 58 from multi-level PSD. The most frequent location was the lumbar spine (54.0%) followed by the thoracic spine (18.0%). The PSD was adjacent in 19.0% and distant in 81.0% of multi-level cases. Fusion rates at the 3 month follow-up did not differ among the multi-level group (p = 0.27 for both adjacent and distant sites). In the single-level group, sufficient fusion was achieved in 70.2% of cases. Pathogen identification was possible 58.5% of the time.

CONCLUSIONS

Surgical treatment of multi-level PSD is a safe option. Our study demonstrates that there was no significant difference in early fusion outcomes between single-level and multi-level PSD, whether adjacent or distant.

Factors associated with spinal fixation mechanical failure after tumor resection: a systematic review and meta-analysis

Background

No available meta-analysis has been published that systematically assessed spinal fixation mechanical failure after tumor resection based on largely pooled data. This systematic review and meta-analysis aimed to investigate the spinal fixation failure rate and potential risk factors for hardware failure.

Methods

Electronic articles published between January 1, 1979, and January 30, 2021, were searched and critically evaluated. The authors independently reviewed the abstracts and extracted data on the spinal fixation failure rate and potential risk factors.

Results

Thirty-eight studies were finally included in the meta-analysis. The pooled spinal fixation mechanical failure rate was 10%. The significant risk factors for hardware failure included tumor level and cage subsidence. Radiotherapy was a potential risk factor.

Conclusion

The spinal fixation mechanical failure rate was 10%. Spinal fixation failure is mainly associated with tumor level, cage subsidence and radiotherapy. Durable reconstruction is needed for patients with these risk factors.

Indications for early revision surgery for material failure in spinal instrumentation: experience at a level 1 center for spinal surgery - a single-center study

Posterior instrumentation is an established treatment for a range of spinal disorders. Material failure is not uncommon, and the indications for a revision are very heterogeneous. This study aimed to evaluate the indications and timing for early revision spinal surgery due to material failure.In this retrospective, single-center cohort study, patients underwent spinal posterior instrumentation between January 2017 and July 2019. They were followed up at 3, 12, and 18 months postoperatively. The time of onset of material failure which led to revision surgery was analyzed. In addition, the relationship between the indications for revision surgery and independent variables was examined using a multivariate logistic regression model.A total of one hundred thirty-five patients were enrolled. Radiolucent zones were found in 30 patients (20%) after 3 months, whereas 48 patients (31%) had radiolucent zones after 12 months. Revision surgery was performed in 13 patients (8.5%). The peak time for revision due to instability was within the first four months of the primary surgery. Multivariate analysis revealed that location, pathology, ASA score, and smoking had no significant impact on the indication for revision surgery, and neither did BMI (P = .042). Non-fusion (P = .007) and radiolucent zones (P = .004), in combination with increased pain (P = .006), were predictors for revision.Our data show that the peak time for early revision of material failure after posterior instrumentation was within the first 4 months of primary surgery. The abnormalities (e.g., radiolucent zones) surrounding the screws without fusion, including persistence of pain, were predictors for revision surgery.

Surgical Causes of Significant Intraoperative Neuromonitoring Signal Changes in Three-Column Spinal Surgery

Study Design

Retrospective case series.

Purpose

To evaluate the risks and causes of neurologic complications in three-column spinal surgery by analyzing intraoperative neurophysiological monitoring (IONM) data.

Overview of Literature

Three-column spinal surgery, which may be required to correct complex spinal deformities or resection of spinal tumors, is known to carry a high risk of neurologic complications. However, few studies reported a specific surgical procedure related to a significant IONM signal change during surgery.

Methods

Multimodality IONM data, including somatosensory-evoked potentials (SSEP) and motor-evoked potentials (MEP), were reviewed in 64 patients who underwent three-column spinal surgery from 2011 to 2015. Surgical procedures included posterior vertebral column resection, pedicle subtraction osteotomy, total en bloc spondylectomy, piecemeal spondylectomy, and corpectomy with laminectomy (n=27) in three cervical, 34 thoracic, and 31 lumbar procedures.

Results

Significant IONM signal changes occurred in 11 of 64 (17.1%) patients. SSEP and MEP were changed in 11 patients. Postoperative neurologic deterioration occurred in 54.5% (6 of 11) of the patients, and two of them were permanent. There was no postoperative neurologic deterioration in patients without significant signal change. Suspected causes of IONM data changes are as follows: adhesion/tethering, translation, contusion, and perfusion.

Conclusions

Based on the results of this study, to enhance neurologic safety in three-column spinal surgery, surgeons should pay attention to protect the spinal cord from mechanical insult, especially when the spinal column was totally destabilized during surgery, and not to compromise perfusion to the spinal cord in close cooperation with a neurologist and anesthesiologist.

Factors Related to Instrumentation Failure in Titanium Mesh Reconstruction for Thoracic and Lumbar Tumors: Retrospective Analysis of 178 Patients

Purpose

To investigate risk factors for instrumentation failure (IF) in titanium (Ti) mesh reconstruction for thoracic and lumbar tumors.

Patients and Methods

The clinical data of patients with thoracic or lumbar tumors who received Ti mesh reconstruction via the posterior approach in our hospital from 2013 to 2018 were analyzed retrospectively. The observation indexes included sex, age, BMI, the vertebra resection mode, the number of resected vertebral segments, application of bone cement, radiotherapy, chemotherapy, revision or primary surgery, and primary tumor metastasis. Correlations between these factors and IF were analyzed by Kaplan–Meier survival and logistics regression analyses.

Results

The 178 patients included 108 males and 70 females with a mean age of 48.09±16.21 (6–78) years and a mean follow-up period of 51.18 (24–90) months. The data showed that 17 patients (9.55%) were inflicted with IF, involving the thoracic vertebra in 11 cases, thoracolumbar vertebrae (T12–L1) in 2 cases, and lumbar vertebrae in 4 cases. The mean interval between surgery to IF was 35.18±14.17 (14–59) months. Univariate analysis showed that total vertebral body resection, the number of resected vertebral segments, radiotherapy and multiple tumor resection were potential factors for IF, while multivariate analysis showed that only total vertebral body resection, the number of resected vertebral segments and radiotherapy were independent factors.

Conclusion

Total vertebra resection, the number of resected vertebral segments (≥2) and radiotherapy before and after operation were significant risk factors related to IF.