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Friday, May 22, 2015

The topic of sagittal imbalance has been studied extensively, and there is a clear association between sagittal balance and outcomes in thoracolumbar fusion patients. The role of sagittal imbalance in lumbar stenosis patients is less clear. The majority of elderly lumbar stenosis patients have some degree of sagittal imbalance, and it is not known how this affects their standing and walking ability. Most stenosis patients with claudication choose to stand in a flexed posture to maximize the volume of the spinal canal, and such a posture results in positive sagittal imbalance and loss of lumbar lordosis. Given that sagittal imbalance in these cases is postural, theoretically it could improve following lumbar decompression if patients are able to stand more upright without neural compression. Dr. Fujii and his colleagues from Tokyo wanted to address this question, so they retrospectively reviewed sagittal balance parameters and clinical outcomes in 88 patients undergoing a spinous process splitting decompression (“recapping laminoplasty”) without fusion. Using a threshold of 4 cm of positive sagittal balance or a pelvic incidence (PI) at least 10 degrees greater than lumbar lordosis (LL) to define sagittal imbalance, 74% of patients had preoperative imbalance. Following decompression, the sagittal vertical axis (SVA) decreased by an average of 2 cm, LL increased by 6 degrees, and there was a corresponding 6 degree decrease in PI-LL. All of these differences were statistically significant. As a result of the improvements in sagittal balance, 43% of patients with pre-operative imbalance had resolution of the radiographic abnormalities. The strongest predictor of the degree of post-operative improvement was the severity of baseline imbalance, with greater improvement observed in those with the greatest imbalance. Age, gender, and the number of levels decompressed did not correlate with the degree of improvement. While a detailed analysis of patient reported outcome measures was not reported, the authors did note that scores on the Zurich Claudication Questionnaire did not correlate with sagittal parameters.

 

The authors should be applauded for addressing a question that spine surgeons face daily, namely how to treat the elderly stenosis patient with claudication and sagittal imbalance. Prior to this publication, the effect of lumbar decompression on sagittal imbalance was unknown. On one hand, disruption of the posterior tension band could predispose the patient to increasing kyphosis. On the other, expanding the volume of the spinal canal might allow patients to stand more upright and improve their sagittal balance. This paper makes it clear that decompression alone can improve sagittal balance by allowing patients to perform a postural correction once their claudication symptoms are resolved. As such, stenosis patients with a non-ankylosed, flexible spine should be considered to have a postural rather than fixed sagittal imbalance. In patients with classic claudication symptoms rather than symptoms related to imbalance, a simple decompression should be sufficient to improve both their claudication symptoms and their radiographic sagittal imbalance. One caveat about this paper is that the authors performed a spinous process splitting decompression, and it is unclear if the results would hold true for a traditional laminectomy. Another limitation is the minimal reporting of patient reported outcomes, though the authors did state there were no correlations between sagittal parameters and patient reported measures. This paper supports the decision to perform a simple decompression in elderly stenosis patients with postural sagittal imbalance. Hopefully this analysis will be repeated for patients treated with traditional laminectomy.

 

Please read Dr. Fujii’s article in the May 15 issue. Does this change how you view sagittal imbalance in the lumbar stenosis patient? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor


Friday, May 15, 2015

The impact of a scholarly paper is typically judged based on the number of citations it receives from other papers. As such, Dr. Steinberger and his colleagues from New York performed a bibliographic analysis in order to determine the 100-most cited lumbar spine surgery papers of all time. They found that the most-cited paper is Scott Boden’s 1990 classic demonstrating high rates of lumbar “pathology” found on MRI in asymptomatic people. The second-most cited paper is on the same topic. Studies describing outcome measures appear frequently in the Top 10, with the Oswestry Disability Index coming in at number 3 and the Roland-Morris Disability Questionnaire at number 8. In a similar vein, Deyo’s guidelines for outcome measures for low back pain are also in the Top 10. Radiographic classification schemes for disk degeneration also feature prominently in the Top 10, including Pfirrman’s classification scheme and Modic’s paper describing endplate changes. Interestingly, there are no clinical trials in the Top 10, with Fritzell’s RCT comparing fusion to non-operative care being the highest ranked clinical study at number 11. While the Spine Patient Outcomes Research Trial (SPORT) was the largest, most expensive lumbar clinical trial ever performed, the paper reporting the results of the RCT for lumbar disk herniation only makes it to number 25 on the list. Somewhat ironically, the RCT was very difficult to interpret due to high rates of crossover, and the observational study on the same topic is probably the more relevant study. However, the observational paper was number 53 on the list. Eugene Carragee’s paper highlighting the inconsistencies in the industry-sponsored bone morphogenetic protein (BMP) studies was the most recent paper on the list, garnering 228 citations since 2011. Not surprisingly, low back pain was the most common topic of the Top 100 papers, including 23 papers. More unexpected was that biomechanical papers were the second most common category, with 16 papers. Spine was the most common journal in which the Top 100 papers were published (63%; JBJS-Am was a distant second with 7%). The University of Washington, Yale University, Emory University, and Dartmouth College were the top 4 institutions, thanks to the work of Rick Deyo, Manohar Panjabi, Scott Boden, and Jim Weinstein.

 

This article is a nice way for individuals, institutions, and journals to be recognized for their contributions. To make it onto the list, the papers generally have had to stand the test of time and are now incorporated in the canon of spine surgery. While impact factor is measured by number of citations, real impact is determined by how a paper can influence clinical practice or healthcare policy. In looking at the Top 100 papers, some have clearly affected practice. The top two papers both reported on the higher rate of “pathology” found on lumbar spine MRIs in asymptomatic patients, alerting clinicians to the fact that imaging findings must be considered in light of the clinical picture rather than in isolation. Three of the top 10 papers were related to outcome measures. These papers have had a major influence on outcomes research, though their effect on clinical practice is inherently secondary. There are multiple papers in the Top 100 that describe rapidly increasing rates of lumbar fusion and the use of more invasive techniques to treat spinal stenosis in elderly patients despite higher complication rates. While the authors who wrote those papers likely hoped that they might give surgeons pause as they consider how to treat elderly stenosis patients, there is no indication that the rates of more invasive surgery on the elderly are slowing down. On the other hand, the articles in the Top 100 looking at BMP were likely responsible both for its rapid adoption and nearly equally as rapid decline. This list of the Top 100 papers in lumbar spine surgery is worth perusing. While research is not always as powerful at changing behavior as reimbursement patterns, industry marketing, and thought-leader opinion, it is nice to see that lots of these papers have changed the way we think and practice. I’m looking forward to the list for cervical spine surgery.


Please read Dr. Steinberger’s paper in the May 15 issue. Have any of these papers changed how you practice? Let us know by leaving a comment on The Spine Blog.

 

Adam Pearson, MD, MS

Associate Web Editor


Saturday, May 09, 2015

Given the generally poor outcomes for chronic low back pain patients treated either surgically or nonoperatively, the spine community is motivated to improve results in this challenging population. Prior studies have shown only modest improvement in the degenerative disc disease (DDD) population following lumbar fusion or cognitive behavioral therapy (Oswestry Disability Improvement at one year approximately 10-15 points for fusion vs. 9-13 points for CBT).1-3 As such, Ms. Rolving and her colleagues from Denmark were interested to determine if a preoperative CBT program for patients undergoing lumbar fusion improved surgical outcomes. They enrolled 90 patients in the study (approximately 60% of eligible patients agreed to enroll), randomized in a 2:1 fashion into the CBT and control groups. Eighty-three percent of the CBT patients completed at least 3 of the 6 two hour group CBT sessions. At one year, there were no significant differences in ODI change scores (the primary outcome measure) between the two groups (-14 CBT vs. -6 control, p=0.08). However, at three months the CBT group had improved 15 points vs. a 1 point decline in the control group. Interestingly, there were no consistent benefits on outcomes measuring catastrophizing or fear avoidance behavior, though the CBT group did have an advantage on these psychological outcomes at 6 months. Only forty-two percent of work-eligible patients in both groups had returned to work by one year. An as-treated analysis showed that patients compliant with assignment to CBT did significantly better than the control group combined with the non-compliant CBT patients.

 

The poor outcomes for DDD patients regardless of treatment modality was the impetus for this study, and the concept that the effects of CBT and fusion could be additive is enticing. While the authors were relatively negative about the benefit of CBT in this trial, I would suggest that the outcome differences were likely clinically meaningful and would be statistically significant in a larger sample. Given that CBT was performed pre-operatively, it is not surprising that the greatest effect was seen early in the study. The benefits of CBT probably fade with time, and this study raises the question of whether CBT for an extended period post-operatively would have led to a longer duration of benefit. If the results had been analyzed as the proportion of patients reaching MCID, it seems likely that this would have also showed a more consistent benefit of CBT. While the as treated analysis showed that patients compliant with CBT improved more than the others, it is impossible to know if this was a result of CBT or that the non-compliant patients were different in other, unmeasured ways that limited their improvement. Similar to other studies, this one confirmed the poor correlation between results on patient reported outcome measures and return to work. The major limitation of this study was the heterogeneous patient population including both DDD patients and spondylolisthesis patients. The listhesis patients tend to have much better surgical outcomes than the DDD patients, so mixing them together makes interpreting the data more difficult (i.e. degenerative spondylolisthesis patients improved 25 points on the ODI one year after surgery in SPORT4). This paper suggests that CBT is likely helpful for fusion patients, and certain subgroups likely benefit more than others. Future work should help to identify those patients who do benefit and also determine the most effective duration of treatment following surgery.


Please read Ms. Rolving’s paper in the May 1 issue. Does this paper encourage you to consider preoperative CBT in your lumbar fusion patients? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 

 

REFERENCES

 

1.            Brox JI, Sorensen R, Friis A, et al. Randomized clinical trial of lumbar instrumented fusion and cognitive intervention and exercises in patients with chronic low back pain and disc degeneration. Spine (Phila Pa 1976) 2003;28:1913-21.

2.            Fairbank J, Frost H, Wilson-MacDonald J, Yu LM, Barker K, Collins R. Randomised controlled trial to compare surgical stabilisation of the lumbar spine with an intensive rehabilitation programme for patients with chronic low back pain: the MRC spine stabilisation trial. BMJ 2005;330:1233.

3.            Fritzell P, Hagg O, Wessberg P, Nordwall A. 2001 Volvo Award Winner in Clinical Studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine (Phila Pa 1976) 2001;26:2521-32; discussion 32-4.

4.            Weinstein JN, Lurie JD, Tosteson TD, et al. Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis. The New England journal of medicine 2007;356:2257-70.

 


Friday, May 01, 2015

Many spine surgery patients are on aspirin (ASA) or other anticoagulants due to the presence of cardiac stents or for other indications. Traditionally, spine surgeons have had patients go off ASA and anticoagulants 5-10 days prior to surgery in order to decrease the risk of bleeding complications. Unfortunately, a small percentage of patients suffer stent thrombosis when ASA is stopped, and some of these patients die as a result. On the other hand, an epidural hematoma can result in an irreversible neurological deficit, and spine surgeons and cardiologists have to attempt to weigh the risks and benefits of continuing or stopping ASA around spine surgery. Not surprisingly, there is not good evidence on this topic to guide decision-making. As such, Dr. Cuellar and colleagues elected to compare outcomes between spine surgery patients with cardiac stents who either stopped ASA five days pre-operatively or continued ASA throughout the perioperative period. Their institution changed their policy around ASA and spine surgery in 2011, which created a natural experiment. Prior to the change, all patients on ASA stopped it 5 days prior to surgery, while after the change patients continued ASA at their regular dose. They compared 100 consecutive spine surgery patients with stents prior to the change (no ASA group) to 100 such patients after the change (ASA group). There were no cases of epidural hematoma in either group, and estimated blood loss and transfusion rates were similar for the two groups. The ASA group had a somewhat shorter average operative time and length of stay, and this likely reflects the fact that fewer patients in this group underwent multilevel lumbar fusions. There were no reported cases of stent thrombosis, and complication rates were similar for the two groups.

 

This topic attempts to answer an important question that spine surgeons face every day. Given the rarity of epidural hematoma or stent thrombosis, a huge number of patients would be need to be studied in order to have sufficient power to detect a difference between patients on or off ASA. The current study was sufficiently powered to detect an increase in epidural hematoma rate from 0.2% to 4.5%, a twenty fold increase. As such, most readers would consider this paper very underpowered. Additionally, the two groups being compared were substantially different, with the ASA group undergoing shorter, smaller magnitude surgeries compared to the no ASA group. These differences were not controlled for and represent potential confounders that could have masked some of the negative effects of ASA on bleeding complications. While some would argue that a randomized trial on this topic would be unethical given the concerns about stent thrombosis in patients coming off ASA, the authors could have matched the cohorts for magnitude of surgery and other patient characteristics. Despite the shortcomings of the current study, it does include a case series of one hundred consecutive spine surgery patients with cardiac stents who underwent surgery without coming off their ASA, and none of them had an epidural hematoma or other significant bleeding complication. On the other hand, no patients in the no ASA group suffered stent thrombosis or a complication related to coming off ASA. This study does give spine surgeons some reassurance that operating through ASA is reasonably safe, though a much larger randomized or better controlled study would need to be performed in order to make any definitive conclusions on the topic.

 

Please read Dr. Cuellar’s article in the May 1 issue. Does this article change how you view the use of ASA perioperatively? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor


Friday, April 24, 2015

Results of industry-sponsored IDE trials comparing cervical disk arthroplasty (CDA) to ACDF have been promising, demonstrating low complication rates, similar patient-reported outcomes, and significantly lower re-operation rates over the short-term. However, adoption of CDA has been relatively slow, likely due to a lack of surgeon enthusiasm related to skepticism of industry-sponsored studies, relatively good outcomes with ACDF, concern about long-term durability, and difficulty obtaining reimbursement. Given the possible cost-savings associated with CDA with its similar upfront costs and a potentially lower re-operation rate compared to ACDF, Dr. Radcliff and associates used the Blue Health Intelligence database to evaluate costs and re-operation rates for CDA and ACDF in a “real-world” retrospective cohort study. While the study was funded by Synthes, the database includes 110 million patients covered by BlueCross BlueShield and reflects actual practice outside the strict confines of an IDE trial. From 2008-2009, they identified 6635 single level ACDF patients and 327 single level CDA patients between the ages of 18 and 60. The CDA group was almost 3 years younger and had a slightly lower comorbidity burden. About 2/3 of patients had claims data for at least two years post-operatively, with follow-up dropping off substantially after that as patients changed healthcare coverage. The authors reported a reoperation rate twice as high for ACDF compared to CDA (approximately 10% vs. 5%). It should be noted that only 10 CDA patients underwent re-operation, so the numbers involved are quite small. The causes of re-operation were not reported, but the authors did report a significantly higher rate of “mechanical complications” in the ACDF cohort, with no such complications being reported in the CDA group. Index surgery costs were about $2,000 less for the CDA group, likely reflecting local differences in contracted prices rather than differences in implant or hospitalization costs. Overall costs of the index operation and three years of follow-up were about $5,000 less for the CDA group, though the causes of these differences were not explored. The average length of stay was about 3.5 hours less for CDA, and there were no significant differences in readmission rates.

 

The findings from this retrospective database study support the findings of prior RCTs demonstrating lower re-operation rates for CDA. However, the results of the current study should be interpreted carefully due to many of the limitations inherent to all database studies as well as some that are unique to the current investigation. The decision to reoperate reflects a subjective choice made by patient and surgeon, and this can be influenced by patient and surgeon characteristics. Given that only 327 CDA patients were included in the study and only 10 of these patients underwent reoperation, specific patient and surgeon factors could influence this rate. As such, the results may not reflect practice across the entire spine community. Additionally, there were likely substantial unmeasured differences between the CDA and ACDF populations, and the authors did not compare characteristics like gender, smoking status, BMI, worker’s compensation status, psychosocial comorbidities, and socioeconomic status between the two groups. All of these factors could have affected outcomes. Costs beyond the initial surgery and hospitalization were undoubtedly affected by reoperation rates, but other factors such as the use of physical therapy, injections, and imaging also affected costs and could have been utilized differently by ACDF and CDA patients. This paper adds to the growing literature that suggests CDA is a reasonable alternative to ACDF with similar clinical outcomes and possibly a lower rate of reoperation and lower costs over the short- and medium-term. Long-term data will likely be needed prior to widespread adoption.

 

Please read Dr. Radcliff’s article on this topic in the April 15 issue. Does this paper change how you view CDA as an alternative to ACDF? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 

About the Blog

Spine Journal
This Blog provides a forum for discussion about high impact articles published in Spine, including the bi-annual publication of "Evidenced-Based Recommendations for Spine Surgery." Website users can use this forum to discuss how the articles have affected their practice and query the authors about their findings and recommendations.