The Spine Blog

Friday, January 12, 2018

Trauma and spine specialists continue to struggle with the decision to obtain cervical spine MRI in addition to a CT scan in trauma patients.  The presence of a neurological deficit is the most widely accepted indication to obtain an MRI. In the absence of a neurological deficit, the principal reason to obtain an MRI is to evaluate soft tissue structures not visualized on a CT scan. Common scenarios in which this is done include the obtunded patient who cannot participate in a clinical examination, a patient with persistent neck pain despite a normal CT scan, and a patient going to the OR for an unstable fracture demonstrated on CT scan when the surgeon wants to evaluate cord compression or soft tissue injury at adjacent levels. However, the benefit of MRI in these situations is debatable. MRI is more sensitive than CT scan in detecting soft tissue injuries, but it is not clear if MRI is able to detect unstable, occult injuries missed on CT scan that could lead to a progressive neurological deficit if not stabilized. In order to better assess the utility of MRI in trauma patients, Schoenfeld and colleagues from Boston used a database to identify over 8,000 trauma patients who had undergone CT scan evaluation. Of these, 693 had also underwent MRI. They performed a propensity score matching process to create two matched cohorts of 668 patients, one of which had received CT scan alone and the other CT scan plus MRI. The groups were matched on age, gender, comorbidities, injury severity scale (ISS), and Glasgow coma scale (GCS). Of the 473 patients who had no injury on CT scan and underwent an MRI, 53 had an injury identified on MRI, and five underwent surgery based on the MRI finding. The authors did not discuss the specifics of these 5 injuries identified on MRI but not on CT scan that prompted surgical intervention. This translates to a need to perform 167 MRIs in order to identify 1 patient who would subsequently undergo surgery. No patients in the CT only group went onto develop a delayed neurological deficit.

The authors have done a nice job performing a large, retrospective, propensity-score matched cohort study in an effort to assess the utility of cervical MRI in the trauma patient. Most trauma and spine specialists would agree that cervical spine MRI is not indicated in the awake, neurologically intact trauma patient with a normal CT scan. It seems likely that this study included many such patients (i.e. there were 632 CT scan alone patients with no injury identified on CT scan), and these patients do not shed much light on the subject. The most controversial decision is whether to obtain an MRI in an obtunded patient with a normal CT scan. This study did not report any new injuries identified on MRI in the obtunded population that resulted in surgical treatment that would not have occurred based on the CT scan alone. Multiple large meta-analyses have also reported that MRI does not identify unstable injuries missed on CT scan in obtunded trauma patients, and these have concluded that obtunded trauma patients can have their cervical spine cleared safely based on CT scan alone.1,2 Like all retrospective studies, this paper has significant limitations. The major limitation is the inability of propensity score matching to take into account injury and clinical characteristics (i.e. neurological deficit, pain, soft-tissue swelling on CT scan, etc.) that likely drove the decision to get the MRI. As such, the two groups are probably not equivalent. Additionally, the authors do not report the number of obtunded patients who had their cervical spine cleared based on CT scan alone, so it is unclear if this represented a sufficient number of patients from which to draw conclusions. The authors’ conclusion that the decision to obtain cervical MRI should be made on a “case-specific basis” is valid, and there is no evidence to support routine use of cervical MRI in all trauma patients.

Please read Dr. Schoenfeld’s article on this topic in the February 1 issue. Does this change how you view the role of cervical MRI in trauma patients? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 

REFERENCES

1.            Patel MB, Humble SS, Cullinane DC, et al. Cervical spine collar clearance in the obtunded adult blunt trauma patient: a systematic review and practice management guideline from the Eastern Association for the Surgery of Trauma. J Trauma Acute Care Surg 2015;78:430-41.

2.            Raza M, Elkhodair S, Zaheer A, Yousaf S. Safe cervical spine clearance in adult obtunded blunt trauma patients on the basis of a normal multidetector CT scan--a meta-analysis and cohort study. Injury 2013;44:1589-95.

 


Thursday, January 4, 2018

Spine researchers have expended significant energy in efforts to predict outcomes following surgical and nonoperative treatment of degenerative conditions, though much less work has been focused on predicting outcomes following spine fractures. This may be a result of spine trauma not being elective. However, identifying fracture patients at risk for poor outcomes could allow providers to allocate more resources for these patients. Due to the lack of literature on this topic, Dr. Vorlat and colleagues from Belgium prospectively gathered outcome data including the Oswestry Disability Index (ODI), visual analog scale (VAS) for back pain, Greenough and Fraser (GF) low back pain score, and patient satisfaction on 48 neurologically intact thoracolumbar compression and burst fracture patients (AO Type A) treated with bracing. The majority of patients (42/48) had compression fractures that did not involve the posterior cortex of the vertebral body, and the remaining 6 had burst fractures that involved the posterior cortex. There was a wide age range (19-85), and the majority (34/48) had sustained high energy trauma including falls from a height, sports injuries, and motor vehicle accidents. Thirteen were injured in ground level falls and one due to lifting. Shortly after admission to the hospital, one of the authors asked patients to recall their baseline status and answer the questionnaires based on their pre-injury condition. The mean ODI score was 8 at baseline and 17 at 12 months. VAS low back pain scores increased from 1 at baseline to 4 at 12 months. Multivariate regression demonstrated that receiving workers’ compensation, smoking, burst fractures, and pre-existent back pain were the strongest predictors of worse outcomes on ODI, VAS, GF, and patient satisfaction. For example, patients receiving workers’ compensation deteriorated 12 points more on the ODI, smokers deteriorated 11 point more, and burst fracture patients deteriorated 16 points more (vs. compression fracture patients).

The authors have done a nice job looking at risk factors for poor outcomes following thoracolumbar compression and burst fractures. Similar to studies looking at treatment outcomes for degenerative conditions, patient factors such as smoking or receiving workers’ compensation tended to be the strongest predictors of outcomes.1 Burst fracture patients did worse on the ODI than compression fracture patients, though these tend to be very different injuries involving a different patient population and a markedly different amount of energy. Sagittal plane deformity and disk height loss did not correlate with outcomes. Prior to drawing conclusions from this paper, its limitations need to be considered. One limitation inherent to all trauma literature is that baseline scores need to be estimated after the injury, and these may not reflect the true baseline. This paper also only included 48 patients, which limited the power of the multivariate regression to assess multiple predictors. The authors also did not include any measure of mental health or depression, factors that have been shown to be among the strongest outcome predictors for degenerative conditions.2 This paper is a nice first foray into outcome predictors following thoracolumbar fracture. While there was not sufficient power to evaluate predictors that may have had more subtle effects, the findings of this paper are in line with the degenerative condition literature that has shown patient factors such as smoking, workers’ compensation, and depression tend to affect outcomes more than disease factors such as severity of stenosis, degree of listhesis, etc. Fracture patients at risk for poor outcomes should be targeted for social and occupational support and physical therapy in an effort to prevent long-term disability.

 

Please read Dr. Vorlat’s article on this topic in the January 15 issue. Does this change how you view outcomes following thoracolumbar fracture? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

REFERENCES

1.            Pearson A, Lurie J, Tosteson T, et al. Who should have surgery for an intervertebral disc herniation? Comparative effectiveness evidence from the spine patient outcomes research trial. Spine 2012;37:140-9.

2.            Slover J, Abdu WA, Hanscom B, Weinstein JN. The impact of comorbidities on the change in short-form 36 and oswestry scores following lumbar spine surgery. Spine (Phila Pa 1976) 2006;31:1974-80.

 


Saturday, December 30, 2017

As 2017 comes to a close, this edition of The Spine Blog will reflect on the hot topics in the journal this year and take a look at readers’ opinions on these issues. Debate on the best fusion technique for various indications continues to remain front and center, especially now that surgeons are equipped with such a broad armamentarium of fusion options. Surgeons employ a wide range of fusion techniques for isthmic spondylolisthesis, without any high level evidence demonstrating the superiority of any given technique. Gala et al. reviewed the NSQUIP database and found no difference in adverse events or length of stay for patients treated with posterolateral fusion, TLIF, ALIF or AP fusion. Interestingly, 100% of respondents to the quick poll asking about surgeons’ preferred technique for low-grade adult isthmic spondylolisthesis indicated they preferred TLIF or PLIF. Degenerative spondylolisthesis remains a controversial subject, with continued debate on whether to fuse and how to fuse. Two Level 1 RCTs were published in 2016 that reached opposite conclusions about the benefits of fusion in addition to decompression for degenerative spondylolisthesis. This year in Spine, Ulrich et al. published an observational study that suggested minimal benefit on patient reported outcomes but possibly a lower re-operation rate associated with fusion. When readers were queried about their preferred surgical technique for a 70 year old female with a “stable” degenerative spondylolisthesis, 45% responded decompression alone, with the remaining 55% equally divided among decompression and uninstrumented fusion, decompression and instrumented fusion, and decompression and interbody fusion. Minimally invasive fusion techniques have become more popular, though the benefits of these less invasive techniques have not been well-established. Lu et al. published a meta-analysis comparing MIS to open fusion for lumbar spondylolisthesis and found less blood loss and shorter length of stay in MIS patients without any difference in patient reported outcomes. When asked about potential advantages of MIS, all quick poll respondents selected less blood loss.

How to address thoracolumbar deformity in the elderly patient remains a vexing topic, with surgeons continuing to debate how much of the curve needs to be fused and how aggressive to be about correcting sagittal balance. Lee et al. performed a meta-analysis comparing long (3 or more segment) vs. short (1 or 2 segment) fusion for adult deformity and found no difference in patient reported outcomes but a higher complication rate and re-operation rate in the long fusion group. When asked about how to address two level stenosis in a 70 year old with a “stable” 20 degree lumbar curve, 71% responded decompression alone and the remaining 29% favored two level decompression and fusion. None indicated they would fuse the entire curve. Lafage et al. published their series of elderly adult deformity patients undergoing thoracolumbar fusion to the pelvis and found that patients who had more aggressive sagittal balance correction were more likely to develop proximal junctional kyphosis (PJK). Readers responded that increasing age and osteoporosis were the biggest risk factors for PJK and did not feel that over- or under-correction were as important.

Spine care delivery and policy were also addressed in multiple articles, with Anandasivam et al. reporting the results of a survey that demonstrated that fewer than 1% of spine surgeons would schedule an appointment for a lumbar disk herniation patient with Medicaid compared to 95% for the same patient with private insurance. A group from Virginia Mason Medical Center wrote an article describing their experience using a panel approach to determining if patients are appropriate candidates for lumbar fusion. They found that of 100 patients who had been offered lumbar fusion by an outside surgeon, only 36 were felt to be appropriate fusion candidates by the panel. Readers were split about whether or not a panel should determine if patients are appropriate for lumbar fusion, with 40% supporting the use of a panel and 60% preferring the traditional decision-making between the patient and surgeon.

Spine care remains a challenging field with many unanswered questions that remain hotly debated. We here at Spine are looking forward to another year of great literature that can hopefully add to the evidence base and help those of us who are making hard clinical decisions on a daily basis. Happy 2018!


Adam Pearson, MD, MS

Associate Web Editor     


Thursday, December 21, 2017

Whenever there are many accepted surgical techniques to deal with a given spine problem, it typically means that either all of them or none of them work. Widely used fusion approaches for lumbar spondylolysis and low grade isthmic spondylolisthesis include posterolateral fusion, TLIF/PLIF, ALIF, and AP fusion. Conventional wisdom suggests that a simple posterolateral fusion has the lowest perioperative complication rate but may have suboptimal long-term outcomes due to its inability to restore foraminal height, a lower fusion rate, and less re-establishment of lumbar lordosis. Anterior-posterior fusion theoretically addresses these technical issues but is assumed to be associated with a higher perioperative complication rate and cost. Surgeons tend to think of TLIF as a compromise between the other two techniques—it offers the advantage of an interbody device (albeit a smaller one) with a better complication profile than AP fusion. Meta-analyses have generally found no differences in clinical outcomes among the different techniques.1 In order to better assess the perioperative outcomes associated with the different techniques, Dr. Gala and colleagues used the NSQIP database to evaluate 30 day outcomes of 1,077 spondylolysis patients undergoing a single level lumbar fusion. All patients had an ICD-9 code for either “spondylolysis” or “congenital spondylolisthesis”. The most common procedure was TLIF (n=556), followed by posterolateral fusion (n=327), AP fusion (n=108), and ALIF (n=86). The TLIF and posterolateral fusion patients were older and had a greater comorbidity burden. The only significant outcome difference among the techniques was a longer operative time for AP fusion compared to the other procedures. There was a trend towards a higher DVT rate in the AP fusion and ALIF groups, though these differences were not present in the propensity-score matched analysis. There were no differences among the groups on specific or overall complication rates, length of stay, or stransfusion rate.

The current paper provides data that contradicts previously published literature that has reported a higher perioperative complication rate for patients undergoing AP fusion compared to posterior-only fusion.2 The limitations of this study need to be considered before drawing any strong conclusions. The most important limitation is the lack of power to detect differences in relatively low complication rates. For example, in the AP fusion and ALIF groups, no specific complication occurred in more than 8 patients. Serious adverse events occurred in only 3 AP fusion patients and 6 ALIF patients. With low numbers like this, there was a high risk for Type II error (i.e. failure to detect a true difference when one existed). One reason for the low number of patients (only about 1,000 over a four year period) may be related to the diagnostic coding. Many surgeons may have coded for an acquired spondylolisthesis, a more general code that can potentially be used for both degenerative and isthmic spondylolisthesis. The other major limitation is the lack of longer-term patient related outcomes. While this paper did not show it, most surgeons would assume that AP-fusion is associated with a higher complication rate and higher costs. The only way to justify these would be through better patient reported outcomes, and those have not been shown in this or other studies. The current paper suggests that AP fusion may not be as morbid as previously reported, and part of that could be related to the adoption of less invasive percutaneous screw placement techniques. The jury remains out on the best fusion technique for spondylolysis and isthmic spondylolisthesis. There is a broad spectrum of pathology within this diagnosistic category, and the best technique likely varies according to both patient characteristics and surgeon familiarity with the different operations. This and other papers support the concept of doing the operation that works best in your hands.

Please read Dr. Gala’s paper on this topic in the January 15 issue. Does this change how you consider fusion technique for lumbar spondylolysis and isthmic spondylolisthesis? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

REFERENCES

1.            Wang SJ, Han YC, Liu XM, et al. Fusion techniques for adult isthmic spondylolisthesis: a systematic review. Arch Orthop Trauma Surg 2014;134:777-84.

2.            Thirukumaran CP, Raudenbush B, Li Y, Molinari R, Rubery P, Mesfin A. National Trends in the Surgical Management of Adult Lumbar Isthmic Spondylolisthesis: 1998 to 2011. Spine (Phila Pa 1976) 2016;41:490-501.

 


Friday, December 15, 2017

Pseudarthrosis is a common phenomenon after ACDF, with rates around typically cited around 10% for a one level procedure and up to 30% or more for a three level fusion. Most surgeons don’t expect a solid fusion before one year, but concern about nonunion tends to develop around the twelve month follow-up. While many patients with radiographic pseudarthrosis at one year are asymptomatic, some have persistent axial neck pain or radiculopathy without evidence of mechanical failure. The best approach to this patient is unknown, and many surgeons would consider a revision fusion procedure to address the pseudarthrosis. In order to address this void in the literature, Dr. Lee and colleagues from Korea published their series of 89 consecutive ACDF patients (51 one level, 26 two level, 12 three level) who had dynamic x-ray and CT scan evaluation at one year follow-up. They had a stringent definition of union, requiring less than 1 mm of motion between spinous processes from extension to flexion, bony union across the fusion site, and no significant radiolucent lines through the graft-bone interface. Based on this definition, they found an overall one year radiographic pseudarthrosis rate of 33% (30% for one level, 35% for two level, and 42% for three level). The radiographic studies were repeated at two years in the pseudarthrosis patients, and they found that 21 out of 29 (73%) had gone onto a solid fusion at two years without any further intervention. Three of the pseudarthrosis patients had evidence of mechanical problems on the one year imaging studies (i.e. screws backing out, bent plate), and all three went onto solid fusion by two years. Patients who had persistent pseudarthrosis at two years had worse axial neck pain and neck disability index scores compared to those with a solid fusion, though there was no difference in arm pain. In logistic regression, the only significant risk factor for pseudarthrosis was multilevel fusion.

Spine surgeons will find this paper very reassuring as the majority of patients with radiographic nonunion at 12 month follow-up went onto a solid fusion by two years without any further intervention. While it can be difficult to continue observation on patients with persistent neck pain and a pseudarthrosis at 12 months, revision fusion in these patients (either anterior or posterior) tends to have mediocre outcomes as the radiographic nonunion may not be the pain generator in all cases. The fact that even patients with evidence of mechanical failure can go onto fuse beyond one year indicates that fusion can be a slow process, and patients and surgeons need to be patient. The main limitation of this study is their very stringent definition of union. Unless a pattern recognition program was used for the intervertebral motion measurements, a threshold of 1 mm of motion to define a nonunion is likely within the measurement error for that technique. Additionally, radiolucent lines between the graft and vertebral body can persist in solid fusions when the fusion occurs around the graft rather than through it. This strict definition of union is likely the reason behind the high one year pseudarthrosis rate reported in this paper, and it seems likely that some cases that were clearly well on their way to fusion at one year were classified as nonunions. This would bias the results towards indicating a better prognosis for going onto a solid fusion by two years as many of their “nonunions” may not have been considered as such by a surgeon in the clinic. It seems as though a patient with 2 mm of motion and some bony bridging at one year has a much better chance of going onto a fusion by two years than a patient with no evidence of fusion and gross motion. Despite this limitation, this paper offers fairly good evidence to suggest there is no need to jump into a revision fusion procedure at 12 months in cases of radiographic pseudarthrosis after ACDF.

Please read Dr. Lee’s paper on this topic in the January 1 issue. Does this change how you consider treating radiographic pseudarthrosis one year after ACDF? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor