Faculty Bibliography

Interbody fusion techniques have been promoted as an adjunct to lumbar fusion procedures in an effort to enhance fusion rates and potentially improve clinical outcome. The medical evidence continues to suggest that interbody techniques are associated with higher fusion rates compared with posterolateral lumbar fusion (PLF) in patients with degenerative spondylolisthesis who demonstrate preoperative instability. There is no conclusive evidence demonstrating improved clinical or radiographic outcomes based on the different interbody fusion techniques. The addition of a PLF when posterior or anterior interbody lumbar fusion is performed remains an option, although due to increased cost and complications, it is not recommended. No substantial clinical benefit has been demonstrated when a PLF is included with an interbody fusion. For lumbar degenerative disc disease without instability, there is moderate evidence that the standalone anterior lumbar interbody fusion (ALIF) has better clinical outcomes than the ALIF plus instrumented, open PLF. With regard to type of interbody spacer used, frozen allograft is associated with lower pseudarthrosis rates compared with freeze-dried allograft; however, this was not associated with a difference in clinical outcome.

The utilization of pedicle screw fixation as an adjunct to posterolateral lumbar fusion (PLF) has become routine, but demonstration of a definitive benefit remains problematic. The medical evidence indicates that the addition of pedicle screw fixation to PLF increases fusion rates when assessed with dynamic radiographs. More recent evidence, since publication of the 2005 Lumbar Fusion Guidelines, suggests a stronger association between radiographic fusion and clinical outcome, although, even now, no clear correlation has been demonstrated. Although several reports suggest that clinical outcomes are improved with the addition of pedicle screw fixation, there are conflicting findings from similarly classified evidence. Furthermore, the largest contemporary, randomized, controlled study on this topic failed to demonstrate a significant clinical benefit with the use of pedicle screw fixation in patients undergoing PLF for chronic low-back pain. This absence of proof should not, however, be interpreted as proof of absence. Several limitations continue to compromise these investigations. For example, in the majority of studies the sample size is insufficient to detect small increments in clinical outcome that may be observed with pedicle screw fixation. Therefore, no definitive statement regarding the efficacy of pedicle screw fixation as a means to improve functional outcomes in patients undergoing PLF for chronic low-back pain can be made. There appears to be consistent evidence suggesting that pedicle screw fixation increases the costs and complication rate of PLF. High-risk patients, including (but not limited to) patients who smoke, patients who are undergoing revision surgery, or patients who suffer from medical conditions that may compromise fusion potential, may appreciate a greater benefit with supplemental pedicle screw fixation. It is recommended, therefore, that the use of pedicle screw fixation as a supplement to PLF be reserved for those patients in whom there is an increased risk of nonunion when treated with only PLF.

The medical literature continues to fail to support the use of lumbar epidural injections for long-term relief of chronic back pain without radiculopathy. There is limited support for the use of lumbar epidural injections for shortterm relief in selected patients with chronic back pain. Lumbar intraarticular facet injections are not recommended for the treatment of chronic lower-back pain. The literature does suggest the use of lumbar medial nerve blocks for short-term relief of facet-mediated chronic lower-back pain without radiculopathy. Lumbar medial nerve ablation is suggested for 3-6 months of relief for chronic lower-back pain without radiculopathy. Diagnostic medial nerve blocks by the double-injection technique with an 80% improvement threshold are an option to predict a favorable response to medial nerve ablation for facet-mediated chronic lower-back pain without radiculopathy, but there is no evidence to support the use of diagnostic medial nerve blocks to predict the outcomes in these same patients with lumbar fusion. There is insufficient evidence to support or refute the use of trigger point injections for chronic lowerback pain without radiculopathy.

The utilization of orthotic devices for lumbar degenerative disease has been justified from both a prognostic and therapeutic perspective. As a prognostic tool, bracing is applied prior to surgery to determine if immobilization of the spine leads to symptomatic relief and thus justify the performance of a fusion. Since bracing does not eliminate motion, the validity of this assumption is questionable. Only one low-level study has investigated the predictive value of bracing prior to surgery. No correlation between response to bracing and fusion outcome was observed; therefore a trial of preoperative bracing is not recommended. Based on low-level evidence, the use of bracing is not recommended for the prevention of low-back pain in a general working population, since the incidence of low-back pain and impact on productivity were not reduced. However, in laborers with a history of back pain, a positive impact on lost workdays was observed when bracing was applied. Bracing is recommended as an option for treatment of subacute low-back pain, as several higher-level studies have demonstrated an improvement in pain scores and function. The use of bracing following instrumented posterolateral fusion, however, is not recommended, since equivalent outcomes have been demonstrated with or without the application of a brace.

Intraoperative monitoring (IOM) is commonly used during lumbar fusion surgery for the prevention of nerve root injury. Justification for its use stems from the belief that IOM can prevent nerve root injury during the placement of pedicle screws. A thorough literature review was conducted to determine if the use of IOM could prevent nerve root injury during the placement of instrumentation in lumbar or lumbosacral fusion. There is no evidence to date that IOM can prevent injury to the nerve roots. There is limited evidence that a threshold below 5 mA from direct stimulation of the screw can indicate a medial pedicle breach by the screw. Unfortunately, once a nerve root injury has taken place, changing the direction of the screw does not alter the outcome. The recommendations formulated in the original guideline effort are neither supported nor refuted with the evidence obtained with the current studies.

In an attempt to enhance the potential to achieve a solid arthrodesis and avoid the morbidity of harvesting autologous iliac crest bone (AICB) for a lumbar fusion, numerous alternatives have been investigated. The use of these fusion adjuncts has become routine despite a lack of convincing evidence demonstrating a benefit to justify added costs or potential harm. Potential alternatives to AICB include locally harvested autograft, calcium-phosphate salts, demineralized bone matrix (DBM), and the family of bone morphogenetic proteins (BMPs). In particular, no option has created greater controversy than the BMPs. A significant increase in the number of publications, particularly with respect to the BMPs, has taken place since the release of the original guidelines. Both DBM and the calciumphosphate salts have demonstrated efficacy as a graft extender or as a substitute for AICB when combined with local autograft. The use of recombinant human BMP-2 (rhBMP-2) as a substitute for AICB, when performing an interbody lumbar fusion, is considered an option since similar outcomes have been observed; however, the potential for heterotopic bone formation is a concern. The use of rhBMP-2, when combined with calcium phosphates, as a substitute for AICB, or as an extender, when used with local autograft or AICB, is also considered an option as similar fusion rates and clinical outcomes have been observed. Surgeons electing to use BMPs should be aware of a growing body of literature demonstrating unique complications associated with the use of BMPs.

The relationship between the formation of a solid arthrodesis and electrical and electromagnetic energy is well established; most of the information on the topic, however, pertains to the healing of long bone fractures. The use of both invasive and noninvasive means to supply this energy and supplement spinal fusions has been investigated. Three forms of electrical stimulation are routinely used: direct current stimulation (DCS), pulsed electromagnetic field stimulation (PEMFS), and capacitive coupled electrical stimulation (CCES). Only DCS requires the placement of electrodes within the fusion substrate and is inserted at the time of surgery. Since publication of the original guidelines, few studies have investigated the use of bone growth stimulators. Based on the current review, no conflict with the previous recommendations was generated. The use of DCS is recommended as an option for patients younger than 60 years of age, since a positive effect on fusion has been observed. The same, however, cannot be stated for patients over 60, because DCS did not appear to have an impact on fusion rates in this population. No study was reviewed that investigated the use of CCES or the routine use of PEMFS. A single low-level study demonstrated a positive impact of PEMFS on patients undergoing revision surgery for pseudarthrosis, but this single study is insufficient to recommend for or against the use of PEMFS in this patient population.

OBJECT: There is significant practice variation and uncertainty as to the value of surgical treatments for lumbar spine disorders. The authors' aim was to establish a multicenter registry to assess the efficacy and costs of common lumbar spinal procedures by using prospectively collected outcomes. METHODS: An observational prospective cohort study was completed at 13 academic and community sites. Patients undergoing single-level fusion for spondylolisthesis or single-level lumbar discectomy were included. The 36-Item Short Form Health Survey (SF-36) and Oswestry Disability Index (ODI) data were obtained preoperatively and at 1, 3, 6, and 12 months postoperatively. Power analysis estimated a sample size of 160 patients: lumbar disc (125 patients) and lumbar listhesis (35 patients). The quality-adjusted life year (QALY) data were calculated using 6-dimension utility index scores. Direct costs and complication costs were estimated using Medicare reimbursement values from 2011, and indirect costs were estimated using the human capital approach with the 2011 US national wage index. Total costs equaled $14,980 for lumbar discectomy and $43,852 for surgery for lumbar spondylolisthesis. RESULTS: There were 198 patients enrolled over 1 year. The mean age was 46 years (49% female) for lumbar discectomy (n = 148) and 58.1 years (60% female) for lumbar spondylolisthesis (n = 50). Ten patients with disc herniation (6.8%) and 1 with listhesis (2%) required repeat operation at 1 year. The overall 1-year follow-up rate was 88%. At 30 days, both lumbar discectomy and single-level fusion procedures were associated with significant improvements in ODI, visual analog scale, and SF-36 scores (p = 0.0002), which persisted at the 1-year evaluation (p < 0.0001). By 1 year, more than 80% of patients in each cohort who were working preoperatively had returned to work. Lumbar discectomy was associated with a gain of 0.225 QALYs over the 1-year study period ($66,578/QALY gained). Lumbar spinal fusion for Grade I listhesis was associated with a gain of 0.195 QALYs over the 1-year study period ($224,420/QALY gained). CONCLUSIONS: This national spine registry demonstrated successful collection of high-quality outcomes data for spinal procedures in actual practice. These data are useful for demonstrating return to work and cost-effectiveness following surgical treatment of single-level lumbar disc herniation or spondylolisthesis. One-year cost per QALY was obtained, and this cost per QALY is expected to improve further by 2 years. This work sets the stage for real-world analysis of the value of health interventions.

Object There is significant practice variation and considerable uncertainty among payers and other major stakeholders as to whether many surgical treatments are effective in actual US spine practice. The aim of this study was to establish a multicenter cooperative research group and demonstrate the feasibility of developing a registry to assess the efficacy of common lumbar spinal procedures using prospectively collected patient-reported outcome measures. Methods An observational prospective cohort study was conducted at 13 US academic and community sites. Unselected patients undergoing lumbar discectomy or single-level fusion for spondylolisthesis were included. Patients completed the 36-item Short-Form Survey Instrument (SF-36), Oswestry Disability Index (ODI), and visual analog scale (VAS) questionnaires preoperatively and at 1, 3, 6, and 12 months postoperatively. Power analysis estimated a sample size of 160 patients: 125 patients with lumbar disc herniation, and 35 with lumbar spondylolisthesis. All patient data were entered into a secure Internet-based data management platform. Results Of 249 patients screened, there were 198 enrolled over 1 year. The median age of the patients was 45.0 years (49% female) for lumbar discectomy (n = 148), and 58.0 years (58% female) for lumbar spondylolisthesis (n = 50). At 30 days, 12 complications (6.1% of study population) were identified. Ten patients (6.8%) with disc herniation and 1 (2%) with spondylolisthesis required reoperation. The overall follow-up rate for the collection of patient-reported outcome data over 1 year was 88.3%. At 30 days, both lumbar discectomy and single-level fusion procedures were associated with significant improvements in ODI, VAS, and SF-36 scores (p