The Spine Blog

Friday, May 26, 2017

There are relatively few prevalence studies looking at lumbar spondylolisthesis, and none have combined radiographs, MRI, and a clinical evaluation. Dr. Ishimoto and his colleagues from Japan involved in the Wakayama Spine Study sought to fill this void by performing a population-based cross-sectional study that evaluated 938 participants over the age of 40. All subjects underwent standing x-rays, lumbar MRI, and a clinical evaluation to determine the presence of back pain, leg pain, and neurogenic claudication. About two thirds of the patients were female, and the average age was 67. Spondylolisthesis was defined as antero- or retrolisthesis greater than 5% of the length of the superior endplate of the caudal vertebra in the motion segment, and both degenerative (DS) and isthmic spondylolisthesis (IS) were included. Thirteen percent of males and 17% of females had spondylolisthesis, and this difference was not statistically significant. Low back pain was about 20% more prevalent in the spondylolisthesis subjects (47% vs. 38%), though this difference did not reach significance either. Symptomatic spinal stenosis, defined as the presence of at least moderate stenosis on MRI and radiculopathy or claudication symptoms, was more than twice as prevalent in patients with listhesis (16% vs. 7%), and nearly three times as common in men with listhesis (20% vs. 8%). The average slip was measured at 14%, and the degree of slip was not related to the presence of symptomatic stenosis.

This paper is a nice cross-sectional study of lumbar spondylolisthesis and represents the first time where a population-based study evaluating lumbar spondylolisthesis included radiographs, MRI, and clinical evaluation. Their findings of nearly equal prevalence among men and women was surprising given that previous studies have found symptomatic DS to be nearly twice as common among women.1 This study did include a mixture of IS, DS, and retrolisthesis (primarily at L3-L4) subjects, so it is possible that the sex-based prevalence differences in DS observed previously were obscured by the inclusion of IS and retrolisthesis patients. Another possibility is that the sex-based prevalence differences in DS are less pronounced in the Japanese population. The major weakness of this paper was the failure to stratify most of the analyses by type of listhesis (i.e. IS, DS, retrolisthesis) as patient characteristics and presenting symptoms can be different among those three subgroups. The association between spondylolisthesis and symptomatic stenosis is not surprising as listhesis of any kind tends to develop with stenosis (i.e. DS tends to cause central and lateral recess stenosis, IS tends to cause foraminal stenosis, and retrolisthesis can cause stenosis in all compartments). The lack of a strong association with low back pain is also not that surprising as listhesis itself does not necessarily cause back pain, but the degenerative changes that accompany it do. As such, the prevalence of back pain is probably similar or only slightly higher in a spondylolisthesis cohort as compared to an age-matched cohort without listhesis (assuming a similar degree of degenerative changes). This finding is in-line with a previous study that showed a similar degree of back and leg pain across spinal stenosis patients stratified by the presence of DS.2 The cross-sectional design of this study limits us to a snapshot in time, so how the radiographic and clinical findings change over time remains unknown. The authors promise a follow-up report in 3 years, which should be illuminating.

Please read Dr. Ishimoto's paper in the June 1 issue. Does this change how you view the association between spondylolisthesis and clinical symptoms? Let us know by leaving a comment on The Spine Blog.

 

Adam Pearson, MD, MS

Associate Web Editor

 

REFERENCES

1.            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.

2.            Pearson A, Blood E, Lurie J, et al. Degenerative spondylolisthesis versus spinal stenosis: does a slip matter? Comparison of baseline characteristics and outcomes (SPORT). Spine (Phila Pa 1976) 2010;35:298-305.

 

 


Friday, May 19, 2017

All spine surgeons are familiar with the time-consuming, frustrating, and stressful experience of trying to determine the appropriate vertebral level in thoracic spine surgery when there are no good radiographic landmarks on which to rely. Unlike cervical and lumbar surgery when the proximity of the occiput or sacrum allows for easy level confirmation, the thoracic spine does not have reliable radiographic landmarks. Counting ribs on the AP fluoroscopic view can help with level confirmation, though significant anatomic variation in the appearance and location of the T12 rib makes this somewhat unreliable. The situation is even worse in the upper thoracic spine, where the shoulder girdle limits visualization. Obesity and osteoporosis complicate the process further as bony structures are more difficult to visualize fluoroscopically. Universal protocols to prevent wrong-site surgery such as marking the site and the “time-out” provide little to no benefit in preventing wrong-level thoracic surgery. Given these challenges, Dr. Madaellil and colleagues from Washington University in St. Louis wrote a succinct technical report describing pre-operative placement of intra-osseous fiducial markers in order to facilitate level identification in thoracic spine surgery. They reported on 19 patients undergoing thoracic spine surgery who had CT-guided placement of a fiducial marker (usually an embolization coil) by interventional radiology prior to surgery. The radiologists placed the marker using a bone biopsy needle advanced into the thoracic vertebra using a transpedicular approach. This allowed for rapid identification of the level intra-operatively using the fluoroscope. They reported no complications related to marker placement and an average cost of under $400.

 

It is rare that a technical report provides interesting fodder for a blog post, but this article is a nice example of a simple technique that can markedly decrease intra-operative radiation exposure, time spent in the operating room localizing the level, surgeon stress, and, most importantly, wrong level surgery. We use this technique at our institution, and it has markedly improved the experience of level identification in the thoracic spine. We used to spend significant amounts of time and radiation to try and find our level using the fluoroscope, and frequently there was at least some degree of uncertainty associated with the process. Now we take one fluoroscopy shot and immediately know where we are. The most challenging aspect related to this technique is probably communicating successfully with the interventional radiologist and having a process that allow for fiducial placement on short notice and during off-hours. Much thoracic spine surgery is non-elective, so having an interventional radiology group that can place the markers on short notice is key to this working well. Additionally, the radiologist needs to target the appropriate level for marker placement, and this generally requires a sagittal MRI view that shows the entire spine so that any anomalous anatomy can be taken into account. While this may not be a groundbreaking new technique, it is a relatively simple solution to a problem that can make thoracic spine surgery vexing. It would be interesting to quantify how much intra-operative time and radiation this method saves, though it is one of those interventions that has obvious benefits and probably does not require an RCT to demonstrate that.

Please read Dr. Madaelil’s article in the May 15 issue. Is this a technique you currently use or would consider adopting? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor   


Friday, May 12, 2017

Workers’ compensation (WC) patients are known to have worse outcomes following lumbar fusion compared to non-compensated patients. Secondary gain issues and a higher burden of psychosocial comorbidities have been blamed for the poor outcomes in the WC population.  Fusion techniques have changed over time, with pedicle screw fixation gaining popularity in the 1990s and posterior interbody techniques becoming mainstream in the early 2000s. Modern instrumentation has clearly improved the fusion rate, but it is unclear if this leads to better patient-reported outcomes. To address this question in the Utah WC population, Dr. Cuneo and colleagues performed a retrospective cohort study in which they compared long-term lumbar fusion outcomes between 110 patients undergoing surgery between 1998-2007 and a historical control from 1990-1995 that included 130 patients. The two groups were similar at baseline, with the more recent cohort about 4 years older (43 vs. 39 years old), more likely to be diagnosed with depression (36% vs. 9%), and more likely to be treated with pedicle screws (99% vs. 83%) and interbody fusion devices (51% vs. 0%). Average follow-up for the more recent group was 6.5 years compared to 4.5 years for the historic group. Overall, the outcomes were similar between the two cohorts, with about 50% reporting great or moderate improvement, 40% reporting satisfaction with the procedure, and 70% stating they would have the operation again. Over 70% of each group returned to at least light duty work. The more recent cohort had a Raymond Morris Disability Questionnaire (RMDQ) score about 2 points worse than the historic cohort and also a much higher use of narcotics at long-term follow-up (50% vs. 26%). The more recent cohort also had a significantly higher fusion rate (89% vs. 72%).

 

The results of this study were similar to prior studies on fusion in the WC population. The novel aspect of the current study was that it compared outcomes across time. Retrospective cohort studies have a host of inherent limitations that need to be considered, and this study is no exception. Political and cultural changes over time can affect who applies for and receives workers’ compensation, how motivated patients are to return to work, and narcotic prescribing habits. This study did not include any baseline patient-reported outcomes, so change scores could not be calculated. Fusion was defined based on chart review of the surgeons’ notes and radiologists’ reports, a likely unreliable way to analyze this outcome. While fusion methods changed over time and appear to have led to a predictably higher fusion rate, this did not seem to affect outcomes in a positive way. If anything, outcomes were somewhat worse in the later cohort, particularly the high rate of narcotic use (which likely reflects changes in prescribing patterns over time). The moderately worse outcomes on the RMDQ could have been due to a variety of factors, one of which was the longer follow-up period for the later cohort. This paper adds indirect evidence to support the case that fusion technique is not a strong driver of patient reported or functional outcomes.1,2 In the WC population, patient and compensation factors are likely much stronger outcome predictors.

 

Please read Dr. Cuneo’s article on this topic in the May 1 issue. Does this change how you view fusion in the WC population? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 

REFERENCES

1.            Abdu WA, Lurie JD, Spratt KF, et al. Degenerative spondylolisthesis: does fusion method influence outcome? Four-year results of the spine patient outcomes research trial. Spine (Phila Pa 1976) 2009;34:2351-60.

2.            Endler P, Ekman P, Moller H, Gerdhem P. Outcomes of Posterolateral Fusion with and without Instrumentation and of Interbody Fusion for Isthmic Spondylolisthesis: A Prospective Study. J Bone Joint Surg Am 2017;99:743-52.

 


Friday, May 5, 2017

Depression is known to be a strong predictor of worse patient reported outcomes following surgical and non-operative treatment of spinal disorders. This has been shown across the domains of pain, disability, and satisfaction with care. Over the past few years, the Centers for Medicare and Medicaid Services (CMS) have started to adjust payments to hospitals using its value-based purchasing program based on quality measures. The Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey is weighted heavily in the calculations that assess hospital quality. It surveys a random selection of patients following hospital discharge and asks them to evaluate their satisfaction with their providers and the hospital. Given the financial implications of patient responses to HCAHPS, the spine surgery group at the Cleveland Clinic decided to analyze the relationship between preoperative depression and HCAHPS scores following lumbar fusion. They identified 217 patients who had completed the Preoperative Patient Health Questionnaire 9 (PPHQ 9), which assesses depression, and who also completed an HCAHPS survey. Based on PPHQ 9 scores, 57 patients were classified as depressed, and 160 as non-depressed. Depression was strongly associated with lower satisfaction with their spine surgeon, nursing staff, and the hospital on HCAHPS surveys. The authors also performed a multivariate regression analysis that demonstrated that depression was the strongest independent predictor of lower satisfaction with providers on HCAPHS.

Given the consistently worse results across a broad range of outcomes for depressed patients, these results come as no surprise. The effect size is impressive, with depressed patients approximately 65% less likely to report that their nurses and doctors treated them with respect, even after controlling for other baseline differences. Even though there were only 57 patients in the depressed group, many of the differences were statistically significant. For the differences that failed to reach significance, the trend was universally towards less satisfaction in the depressed group. With a larger sample size, the depressed group would likely have had significantly worse HCAHPS scores on nearly every question. This paper makes it clear that hospitals that choose to care for depressed patients, and likely other groups of patients with significant comorbidities, are at risk for financial penalties given that these patients will rate their hospitals and providers lower on HCAHPS as compared to non-depressed patients. This paper highlights just one small aspect of how basing reimbursement on patient surveys is problematic. There are likely countless other characteristics (i.e. medical comorbidities, low educational attainment, narcotic use, receiving disability payments, smoking, etc.) that are associated with lower HCAHPS scores, and current efforts by CMS to control for these in their analysis are woefully deficient. If financial incentives to obtain high HCAHPS score are sufficiently strong, health systems will make efforts to avoid caring for patients with these characteristics. Additionally, many of the characteristics associated with poor patient satisfaction are likely more common in patients who are uninsured, underinsured, or on Medicaid. Hospital systems already take a financial hit for caring for these patients due to the low levels of reimbursement they receive, so CMS should be cautious about creating further financial disincentives to care for this vulnerable patient population.

Please read the article on this topic by Levin et al. in the May 1 issue. Does this change how you view the use of patient satisfaction surveys (i.e. HCAHPS) in determining hospital and physician reimbursement? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 


Friday, April 28, 2017

Lateral lumbar interbody fusion (LLIF) techniques continue to evolve, and the role of this technology is being defined. One potentially attractive use of LLIF is for adjacent segment disease (ASD). Traditional posterior approaches for ASD typically require removing or revising existing hardware and performing a decompressive procedure in an epidural space that frequently has a significant amount of scarring related to the prior surgery. LLIF is appealing in this situation as the approach is through virgin tissue, and decompression of foraminal and lateral recess stenosis can frequently be performed indirectly by restoring the disk height and correcting any coronal plane deformity. While there is anecdotal support to use LLIF for this indication, there is scant literature on the topic. As such, Dr. Aichmair and colleagues from New York elected to publish their retrospective case series of 52 patients who had been treated with LLIF for ASD. The average age in the cohort was 62, and about 2/3 of patients were women. Sixty percent underwent a stand-alone LLIF without posterior instrumentation, with the remainder undergoing posterior instrumentation with or without decompression as well. Bone morphogenetic protein-2 was used as bone graft in 80% of cases. The average follow-up was 16 months, ranging from 5-44 months. The authors reported that back pain improved 3.8 points on a 10 point scale, while leg pain improved 4.1 points at final follow-up. The overall reoperation rate was 21%, with reoperation occurring at a mean of 14 months following LLIF. The indications for reoperation included ASD, the need for posterior decompression at the LLIF level, and pseudarthrosis. The reoperation rate trended higher in the stand-alone LLIF group compared to the group with supplemental posterior stabilization (26% vs. 14%). Among patients who underwent a CT scan at more than 12 months post-operatively (n=21), the pseudarthrosis rate appeared higher in the stand-alone group (46% vs. 12%).

 

Given that there is effectively no published literature on this topic, this case series is a nice addition and describes the authors’ experience with using LLIF for ASD. This study has all of the limitations inherent to a retrospective case series, the most significant of which is that there is no comparison group. As such, it is very difficult to gauge whether this is an effective technique. While all of the details are not provided, one can assume this is a relatively heterogeneous patient population who underwent a variety of different procedures (i.e. stand-alone LLIF vs. additional posterior fusion with or without direct decompression). The patient reported outcomes are quite rudimentary, limited to a VAS for back and leg pain. Additionally, the authors admit that many of the patients did not complete the VAS, and the VAS was estimated from the narrative portion of the surgeon’s progress note (they did not report how many were estimated). The data on pseudarthrosis is interesting, though fewer than 50% of patients had a post-operative CT scan obtained over a year out from surgery, so there is likely selection bias in terms of who received a CT scan (i.e. there was probably concern for pseudarthrosis in many of those who underwent CT scan). Finally, there is minimal data on complications. While hip flexor weakness is a well-described and common complication following LLIF, the authors simply noted that a similar proportion of patients had a motor deficit following surgery as compared to baseline. They did not make an effort to define how many had a new motor deficit. This paper clearly has many limitations, but it does suggest that LLIF may be a reasonable option for some patients with ASD. Future studies will have to define who this population is. One concerning result from this paper is the relatively high rate of reoperation and pseudarthrosis, especially among the stand-alone group. If it turns out that the stand-alone technique has an unacceptably high failure rate and a posterior procedure is required, it is hard to imagine that the addition of LLIF to a posterior surgery leads to markedly better results than a posterior procedure alone.

Please read Dr. Aichmair’s paper on this topic in the May 1 issue. Do you have experience using LLIF for ASD? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS
Associate Web Editor