Vertebral body reconstruction with a modified Harrington rod distraction system for stabilization of the spine affected with metastatic disease

Evolution of materials for implants in metastatic spine disease till date - Have we found an ideal material?

"Metastatic Spine Disease" (MSD) often requires surgical intervention and instrumentation with spinal implants. Ti6Al4V is widely used in metastatic spine tumor surgery (MSTS) and is the current implant material of choice due to improved biocompatibility, mechanical properties, and compatibility with imaging modalities compared to stainless steel. However, it is still not the ideal implant material due to the following issues. Ti6Al4V implants cause stress-shielding as their Young's modulus (110 gigapascal [GPa]) is higher than cortical bone (17-21 GPa). Ti6Al4V also generates artifacts on CT and MRI, which interfere with the process of postoperative radiotherapy (RT), including treatment planning and delivery. Similarly, charged particle therapy is hindered in the presence of Ti6Al4V. In addition, artifacts on CT and MRI may result in delayed recognition of tumor recurrence and postoperative complications. In comparison, polyether-ether-ketone (PEEK) is a promising alternative. PEEK has a low Young's modulus (3.6 GPa), which results in optimal load-sharing and produces minimal artifacts on imaging with less hinderance on postoperative RT. However, PEEK is bioinert and unable to provide sufficient stability in the immediate postoperative period. This issue may possibly be mitigated by combining PEEK with other materials to form composites or through surface modification, although further research is required in these areas. With the increasing incidence of MSD, it is an opportune time for the development of spinal implants that possess all the ideal material properties for use in MSTS. Our review will explore whether there is a current ideal implant material, available alternatives and whether these require further investigation.

Bone graft options for spinal fusion following resection of spinal column tumors: systematic review and meta-analysis

OBJECTIVE With the advent of new adjunctive therapy, the overall survival of patients harboring spinal column tumors has improved. However, there is limited knowledge regarding the optimal bone graft options following resection of spinal column tumors, due to their relative rarity and because fusion outcomes in this cohort are affected by various factors, such as radiation therapy (RT) and chemotherapy. Furthermore, bone graft options are often limited following tumor resection because the use of local bone grafts and bone morphogenetic proteins (BMPs) are usually avoided in light of microscopic infiltration of tumors into local bone and potential carcinogenicity of BMP. The objective of this study was to review and meta-analyze the relevant clinical literature to provide further clinical insight regarding bone graft options. METHODS A web-based MEDLINE search was conducted in accordance with preferred reporting items for systematic review and meta-analysis (PRISMA) guidelines, which yielded 27 articles with 383 patients. Information on baseline characteristics, tumor histology, adjunctive treatments, reconstruction methods, bone graft options, fusion rates, and time to fusion were collected. Pooled fusion rates (PFRs) and I² values were calculated in meta-analysis. Meta-regression analyses were also performed if each variable appeared to affect fusion outcomes. Furthermore, data on 272 individual patients were available, which were additionally reviewed and statistically analyzed. RESULTS Overall, fusion rates varied widely from 36.0% to 100.0% due to both inter- and intrastudy heterogeneity, with a PFR of 85.7% (I² = 36.4). The studies in which cages were filled with morselized iliac crest autogenic bone graft (ICABG) and/or other bone graft options were used for anterior fusion showed a significantly higher PFR of 92.8, compared with the other studies (83.3%, p = 0.04). In per-patient analysis, anterior plus posterior fusion resulted in a higher fusion rate than anterior fusion only (98.8% vs 86.4%, p < 0.001). Although unmodifiable, RT (90.3% vs 98.6%, p = 0.03) and lumbosacral tumors (74.6% vs 97.9%, p < 0.001) were associated with lower fusion rates in univariate analysis. The mean time to fusion was 5.4 ± 1.4 months (range 3-9 months), whereas 16 of 272 patients died before the confirmation of solid fusion with a mean survival of 3.1 ± 2.1 months (range 0.5-6 months). The average time to fusion of patients who received RT and chemotherapy were significantly longer than those who did not receive these adjunctive treatments (RT: 6.1 months vs 4.3 months, p < 0.001; chemotherapy: 6.0 months vs 4.3 months, p = 0.02). CONCLUSIONS Due to inter- and intrastudy heterogeneity in patient, disease, fusion criteria, and treatment characteristics, the optimal surgical techniques and factors predictive of fusion remain unclear. Clearly, future prospective, randomized studies will be necessary to better understand the issues surrounding bone graft selection following resection of spinal column tumors.

Spinal cord compression secondary to bone metastases from hepatocellular carcinoma

Bone metastases are rare in primary hepatocellular carcinoma (HCC). Spinal cord compression (SCC) due to bone metastases occur commonly in patients with lung and breast carcinomas, and metastatic HCC is an unusual cause of SCC. Spinal cord compression is an oncologic emergency and treatment delays can lead to irreversible consequences. Thus, the awareness that SCC could be a potential complication of bone metastases due to HCC is of significance in initiation of early treatment that can improve the quality of life and survival of the patients, if diagnosed earlier. This paper describes four cases of primary HCC with varied manifestations of SCC due to bone metastases. The first patient presented primarily with the symptoms of bone pains corresponding to the bone metastases sites rather than symptoms of associated hepatic pathology and eventually developed SCC. The second patient, diagnosed as having HCC, developed extradural SCC leading to paraplegia during the course of illness, for which he underwent emergency laminectomy with posterior fixation. The third patient developed SCC soon after the primary diagnosis and had to undergo emergency laminectomy. Post laminectomy he had good neurological recovery. The Fourth patient presented primarily with radicular pains rather than frank paraplegia as the first manifestation of SCC.

Systematic Review of the Diagnosis and Management of Malignant Extradural Spinal Cord Compression: The Cancer Care Ontario Practice Guidelines Initiative‘s Neuro-Oncology Disease Site Group

Purpose

This systematic review describes the diagnosis and management of adult patients with a suspected or confirmed diagnosis of extradural malignant spinal cord compression (MSCC).

Methods

MEDLINE, CANCERLIT, and the Cochrane Library databases were searched to January 2004 using the following terms: spinal cord compression, nerve compression syndromes, spinal cord neoplasms, clinical trial, meta-analysis, and systematic review.

Results

Symptoms for MSCC include sensory changes, autonomic dysfunction, and back pain; however, back pain was not predictive of MSCC. The sensitivity and specificity for magnetic resonance imaging (MRI) range from 0.44 to 0.93 and 0.90 to 0.98, respectively, in the diagnosis of MSCC. The sensitivity and specificity for myelography range from 0.71 to 0.97 and 0.88 to 1.00, respectively. A randomized study detected higher ambulation rates in patients with MSCC who received high-dose dexamethasone before radiotherapy (RT) compared with patients who did not receive corticosteroids before RT (81% v 63% at 3 months, respectively; P = .046). There is no direct evidence that supports or refutes the type of surgery patients should have for the treatment of MSCC, whether surgical salvage should be attempted if patient is progressing on or shortly after RT, and whether patients with spinal instability should be treated with surgery.

Conclusion

Patients with symptoms of MSCC should be managed to minimize treatment delay. MRI is the preferred imaging technique. Treatment for patients with MSCC should consider pretreatment ambulatory status, comorbidities, technical surgical factors, the presence of bony compression and spinal instability, potential surgical complications, potential RT reactions, and patient preferences.

A meta-analysis of surgery versus conventional radiotherapy for the treatment of metastatic spinal epidural disease

Radiotherapy has been the primary therapy for managing metastatic spinal disease; however, surgery that decompresses the spinal cord circumferentially, followed by reconstruction and immediate stabilization, has also proven effective. We provide a quantitative comparison between the "new" surgery and radiotherapy, based on articles that report on ambulatory status before and after treatment, age, sex, primary neoplasm pathology, and spinal disease distribution. Ambulation was categorized as "success" or "rescue" (proportion of patients ambulatory after treatment and proportion regaining ambulatory function, respectively). Secondary outcomes were also analyzed. We calculated cumulative success and rescue rates for our ambulatory measurements and quantified heterogeneity using a mixed-effects model. We investigated the source of the heterogeneity in both a univariate and multivariate manner with a meta-regression model. Our analysis included data from 24 surgical articles (999 patients) and 4 radiation articles (543 patients), mostly uncontrolled cohort studies (Class III). Surgical patients were 1.3 times more likely to be ambulatory after treatment and twice as likely to regain ambulatory function. Overall ambulatory success rates for surgery and radiation were 85% and 64%, respectively. Primary pathology was the principal factor determining survival. We present the first known formal meta-analysis using data from nonrandomized clinical studies. Although we attempted to control for imbalances between the surgical and radiation groups, significant heterogeneity undoubtedly still exists. Nonetheless, we believe the differences in the outcomes indicate a true difference resulting from treatment. We conclude that surgery should usually be the primary treatment with radiation given as adjuvant therapy. Neurologic status, overall health, extent of disease (spinal and extraspinal), and primary pathology all impact proper treatment selection.

Evidence-based review of the surgical management of vertebral column metastatic disease

Object

Significant controversy exists over the most appropriate treatment for patients with metastatic disease of the vertebral column. Treatment options include surgical intervention, radiotherapy, or a combination of the two; nevertheless, a standard of care that yields the best survival, outcome, and quality of life has not been established. The purpose of this review was to determine the foundation in the literature of views favoring surgical intervention for spinal metastatic disease.

Methods

A search of the English-language literature published between 1964 and 2003 was performed for the subject of spinal metastatic disease. Papers were selected based on the inclusion criteria described, and evidentiary information was compiled and graded using previously described methods.

Conclusions

Although there is insufficient evidence to support a standard for surgical treatment in patients with metastatic spinal disease, the authors present guidelines and recommendations based on the evidence provided by the current literature.

Spinal stabilization by using crossed-screw anterior-posterior fixation after multisegmental total spondylectomy for thoracic chondrosarcoma. Case report

The authors describe the case of a 41-year-old man with high-grade chondrosarcoma who presented with a paraspinous mass extending into three thoracic vertebrae (T10-12). Crossfixed long anterior and posterior instrumentation was placed after three complete spondylectomies (T10-12). This technique augments spinal stability with an outrigger effect by using crossfixators placed between paired dorsal rods, as well as between the anterior and posterior hardware components. This technique may be used as an alternative when multiple vertebrae or all three spinal columns are involved by radioresistant malignant tumors in patients in whom there is a relatively long life expectancy.