Andrew C. Hecht

Lumbar discography: A comprehensive review of outcome studies, diagnostic accuracy, and principles

Background and Objectives: Since its advent more than 50 years ago, the use of discography has been mired in controversy. The purpose of this review is to provide a clinical overview of lumbar discography and discogenic back pain, with special emphasis on determining the accuracy of discography and whether or not the procedure improves outcomes for surgery. Methods: Material for this review was obtained from a MEDLINE search conducted from 1951 thru September 2004, bibliographic references, book chapters, and conference proceedings. Results: Based on a large number of comparative studies, plain discography is less accurate than magnetic resonance imaging in diagnosing lumbar herniated nucleus pulposus and comparable or slightly more sensitive in detecting degenerative disc disease. For disc degeneration, CT discography remains the gold standard for diagnosis. There are very few studies comparing surgical outcomes between patients who have undergone preoperative provocative discography and those who have not. What little evidence exists is conflicting. Before disc replacement surgery, approximately half the studies have used preoperative discography. A comparison of outcomes did not reveal any significant difference between the 2 groups but none of the studies was controlled, and they used different outcome measures, follow-up periods, and surgical techniques. Because all intradiscal electrothermal therapy (IDET) studies have used discography before surgery, no conclusions can be drawn regarding its effects on outcome. Conclusions: Although discography, especially combined with CT scanning, may be more accurate than other radiologic studies in detecting degenerative disc disease, its ability to improve surgical outcomes has yet to be proven. In the United States and Europe, there are inconsistencies in the use of lumbar discography such that it is routinely used before IDET, yet only occasionally used before spinal fusion.

A role for TNFα in intervertebral disc degeneration: A non-recoverable catabolic shift

This study examines the effect of TNFα on whole bovine intervertebral discs in organ culture and its association with changes characteristic of intervertebral disc degeneration (IDD) in order to inform future treatments to mitigate the chronic inflammatory state commonly found with painful IDD. Pro-inflammatory cytokines such as TNFα contribute to disc pathology and are implicated in the catabolic phenotype associated with painful IDD. Whole bovine discs were cultured to examine cellular (anabolic/catabolic gene expression, cell viability and senescence using β-galactosidase) and structural (histology and aggrecan degradation) changes in response to TNFα treatment. Control or TNFα cultures were assessed at 7 and 21 days; the 21 day group also included a recovery group with 7 days TNFα followed by 14 days in basal media. TNFα induced catabolic and anti-anabolic shifts in the nucleus pulposus (NP) and annulus fibrosus (AF) at 7 days and this persisted until 21 days however cell viability was not affected. Data indicates that TNFα increased aggrecan degradation products and suggests increased β-galactosidase staining at 21 days without any recovery. TNFα treatment of whole bovine discs for 7 days induced changes similar to the degeneration processes that occur in human IDD: aggrecan degradation, increased catabolism, pro-inflammatory cytokines and nerve growth factor expression. TNFα significantly reduced anabolism in cultured IVDs and a possible mechanism may be associated with cell senescence. Results therefore suggest that successful treatments must promote anabolism and cell proliferation in addition to limiting inflammation.

Genetic polymorphisms associated with intervertebral disc degeneration

BACKGROUND CONTEXT Disc degeneration (DD) is a multifaceted chronic process that alters the structure and function of the intervertebral discs and can lead to painful conditions. The pathophysiology of degeneration is not well understood, but previous studies suggest that certain genetic polymorphisms may be important contributing factors leading to an increased risk of DD. PURPOSE To review the genetic factors in DD with a focus on polymorphisms and their putative role in the pathophysiology of degeneration. Elucidating the genetic components that are associated with degeneration could provide insights into the mechanism of the process. Furthermore, defining these relationships and eventually using them in a clinical setting may allow an identification and early intervention for those who are at a high risk for painful DD. STUDY DESIGN Literature review. METHODS This literature review focused on the studies concerning genetic polymorphisms and their associations with DD. RESULTS Genetic polymorphisms in 20 genes have been analyzed in association with DD, including vitamin D receptor, growth differentiation factor 5 (GDF5), aggrecan, collagen Types I, IX, and XI, fibronectin, hyaluronan and proteoglycan link protein 1 (HAPLN1), thrombospondin, cartilage intermediate layer protein (CILP), asporin, MMP1, 2, and 3, parkinson protein 2, E3 ubiquitin protein ligase (PARK2), proteosome subunit β type 9 (PSMB9), tissue inhibitor of metalloproteinase (TIMP), cyclooxygenase-2 (COX2), and IL1α, IL1β, and IL6. Each genetic polymorphism codes for a protein that has a functional role in the pathogenesis of DD. CONCLUSIONS There are known associations between several genetic polymorphisms and DD. Of the 20 genes analyzed, polymorphisms in vitamin D receptor, aggrecan, Type IX collagen, asporin, MMP3, IL1, and IL6 show the most promise as functional variants. Genetic studies are crucial for understanding the mechanism of the degeneration. This genetic information could eventually be used as a predictive model for determining a patients risk for symptomatic DD.

Cost-effectiveness analysis: comparing single-level cervical disc replacement and single-level anterior cervical discectomy and fusion: clinical article.

OBJECT In recent years, there has been increased interest in the use of cervical disc replacement (CDR) as an alternative to anterior cervical discectomy and fusion (ACDF). While ACDF is a proven intervention for patients with myelopathy or radiculopathy, it does have inherent limitations. Cervical disc replacement was designed to preserve motion, avoid the limitations of fusion, and theoretically allow for a quicker return to activity. A number of recently published systematic reviews and randomized controlled trials have demonstrated positive clinical results for CDR, but no studies have revealed which of the 2 treatment strategies is more cost-effective. The purpose of this study was to evaluate the cost-effectiveness of CDR and ACDF by using the power of decision analysis. Additionally, the authors aimed to identify the most critical factors affecting procedural cost and effectiveness and to define thresholds for durability and function to focus and guide future research. METHODS The authors created a surgical decision model for the treatment of single-level cervical disc disease with associated radiculopathy. The literature was reviewed to identify possible outcomes and their likelihood following CDR and ACDF. Health state utility factors were determined from the literature and assigned to each possible outcome, and procedural effectiveness was expressed in units of quality-adjusted life years (QALYs). Using ICD-9 procedure codes and data from the Nationwide Inpatient Sample, the authors calculated the median cost of hospitalization by multiplying hospital charges by the hospital-specific cost-to-charge ratio. Gross physician costs were determined from the mean Medicare reimbursement for each current procedural terminology (CPT) code. Uncertainty as regards both cost and effectiveness numbers was assessed using sensitivity analysis. RESULTS In the reference case, the model assumed a 20-year duration for the CDR prosthesis. Cervical disc replacement led to higher average QALYs gained at a lower cost to society if both strategies survived for 20 years (

Outcomes and complications of diabetes mellitus on patients undergoing degenerative lumbar spine surgery.

3042/QALY for CDR vs

National Trends in Outpatient Surgical Treatment of Degenerative Cervical Spine Disease

8760/QALY for ACDF). Sensitivity analysis revealed that CDR needed to survive at least 9.75 years to be considered a more cost-effective strategy than ACDF. Cervical disc replacement becomes an acceptable societal strategy as the prosthesis survival time approaches 11 years and the

Anterior Spinal Arthrodesis With Structural Cortical Allografts and Instrumentation for Spine Tumor Surgery

50,000/QALY gained willingness-to-pay threshold is crossed. Sensitivity analysis also indicated that CDR must provide a utility state of at least 0.796 to be cost-effective. CONCLUSIONS Both CDR and ACDF were shown to be cost-effective procedures in the reference case. Results of the sensitivity analysis indicated that CDR must remain functional for at least 14 years to establish greater cost-effectiveness than ACDF. Since the current literature has yet to demonstrate with certainty the actual durability and long-term functionality of CDR, future long-term studies are required to validate the present analysis.

The impact of diabetes mellitus on patients undergoing degenerative cervical spine surgery.

Study Design. Retrospective database analysis. Objective. To assess the effect glycemic control has on perioperative morbidity and mortality in patients undergoing elective degenerative lumbar spine surgery. Summary of Background Data. Diabetes mellitus (DM) is a prevalent disease of glucose dysregulation that has been demonstrated to increase morbidity and mortality after spine surgery. However, there is limited understanding of whether glycemic control influences surgical outcomes in patients with DM undergoing lumbar spine procedures for degenerative conditions. Methods. The Nationwide Inpatient Sample was analyzed from 2002 to 2011. Hospitalizations were isolated on the basis of International Classification of Diseases, Ninth Revision, Clinical Modification, procedural codes for lumbar spine surgery and diagnoses codes for degenerative conditions of the lumbar spine. Patients were then classified into 3 cohorts: controlled diabetic, uncontrolled diabetic, and nondiabetic. Patient demographic data, acute complications, and hospitalization outcomes were determined for each cohort. Results. A total of 403,629 (15.7%) controlled diabetic patients and 19,421 (0.75%) uncontrolled diabetic patients underwent degenerative lumbar spine surgery from 2002 to 2011. Relative to nondiabetic patients, uncontrolled diabetic patients had significantly increased odds of cardiac complications, deep venous thrombosis, and postoperative shock; in addition, uncontrolled diabetic patients also had an increased mean length of stay (approximately, 2.5 d), greater costs (1.3-fold), and a greater risk of inpatient mortality (odds ratio = 2.6, 95% confidence interval = 1.5–4.8, P < 0.0009). Controlled diabetic patients also had increased risk of acute complications and inpatient mortality when compared with nondiabetic patients, but not nearly to the same magnitude as uncontrolled diabetic patients. Conclusion. Suboptimal glycemic control in diabetic patients undergoing degenerative lumbar spine surgery leads to increased risk of acute complications and poor outcomes. Patients with uncontrolled DM, or poor glucose control, may benefit from improving glycemic control prior to surgery. Level of Evidence: 3

C5 nerve root palsy following decompression of the cervical spine: a systematic evaluation of the literature

Study Design Retrospective population-based observational study. Objective To assess the growth of cervical spine surgery performed in an outpatient setting. Methods A retrospective study was conducted using the United States Healthcare Cost and Utilization Projects State Inpatient and Ambulatory Surgery Databases for California, New York, Florida, and Maryland from 2005 to 2009. Current Procedural Terminology, fourth revision (CPT-4) and International Classification of Diseases, ninth revision Clinical Modification (ICD-9-CM) codes were used to identify operations for degenerative cervical spine diseases in adults (age > 20 years). Disposition and complication rates were examined. Results There was an increase in cervical spine surgeries performed in an ambulatory setting during the study period. Anterior cervical diskectomy and fusion accounted for 68% of outpatient procedures; posterior decompression made up 21%. Younger patients predominantly underwent anterior fusion procedures, and patients in the eighth and ninth decades of life had more posterior decompressions. Charlson comorbidity index and complication rates were substantially lower for ambulatory cases when compared with inpatients. The majority (>99%) of patients were discharged home following ambulatory surgery. Conclusions Recently, the number of cervical spine surgeries has increased in general, and more of these procedures are being performed in an ambulatory setting. The majority (>99%) of patients are discharged home but the nature of analyzing administrative data limits accurate assessment of postoperative complications and thus patient safety. This increase in outpatient cervical spine surgery necessitates further discussion of its safety.

Inflammatory Kinetics and Efficacy of Anti-inflammatory Treatments on Human Nucleus Pulposus Cells.

Study Design. The authors report on anterior vertebral reconstruction following tumor resection with use of fresh-frozen, cortical, long-segment allografts prepared from diaphyseal sections of long bones. A retrospective analysis of clinical outcomes is presented. Objective. To analyze the results following the use of cortical allografts in the treatment of spine tumors. Summary of Background Data. Metastatic disease and primary spinal bone tumors may result in progressive vertebral collapse, instability, deformity, pain, and neurologic deficit. Controversy as to the appropriate type of anterior reconstruction and/or graft material persists. Methods. From 1995 until 2001, 30 patients with primary spinal bone tumors or metastases to the spine were treated by anterior vertebral reconstruction with fresh-frozen cortical bone allografts. Grafts were used in combination with anterior and posterior instrumentation. Results. The median survival was 14 months. Ninety-three percent of all allografts were radiographically incorporated as early as 6 months after surgery in spite of adjuvant chemotherapy and radiation therapy. Fourteen patients (46%) had intraoperative or postoperative complications. Two patients underwent revision surgery for local recurrence. There were no allograft infections, fractures, or collapse. Conclusion. Anterior column reconstruction with structural cortical allografts proved to be a reliable technique in patients with spine tumors. Postoperative complications can often be successfully managed.