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Friday, February 27, 2015

Extension-distraction injuries in the ankylosed spine have long been recognized as unstable injuries with high rates of spinal cord injury (SCI), surgical complications, and mortality. These poor outcomes result from both the unstable nature of these fractures as well as from the advanced age of the patients and their accompanying comorbidities. Additionally, surgical stabilization tends to require long posterior constructs that can be complicated by significant intra-operative blood loss and relatively high infection rates. The literature on this topic contains primarily case series including fractures from all regions of the spine treated with a variety of surgical and non-operative approaches. Dr. Robinson and his colleagues in Sweden elected to publish their series of 41 cervical extension-distraction injuries in the ankylosed spine, including both ankylosing spondylitis and DISH patients. All patients were treated with long, posterior constructs from the upper cervical spine (C2 in most patients, with 4 requiring fixation to C1 or the occiput) to the upper thoracic spine. The 27% of patients with SCI also underwent decompression. The average age was 71, though a 95 year old was included, and the vast majority of patients were men. Twenty four percent of patients died within 1 year, and the median survival was 52 months. Not surprisingly, older patients, males, smokers, and those with SCI were significantly more likely to die. The average blood loss was over 2L, with 17L of blood loss in one case. Twelve percent of patients developed surgical site infection, though most were treated with antibiotics without the need for debridement. All patients healed their fractures, and none suffered hardware failure.

 

This study makes a valuable contribution to the literature on these difficult fractures. The study population and treatment approach is more homogenous than most of the existing literature, and the authors have demonstrated that a long posterior construct is a highly effective approach to stabilizing these injuries and consistently results in healing. There is consensus in the spine community that these fractures are best treated surgically, and most spine surgeons likely agree with the authors of the current paper that a long posterior construct is best for most patients. The high blood loss and infection rate are consistent with prior reports, and anticipating these challenges should allow surgeons to deal with them more effectively. Additionally, these data should be shared with patients and their families so that they have realistic expectations and are not surprised when complications arise. The good news from this study is that if patients survive the initial injury and surgery, they will likely heal their fracture. Long-term outcomes are likely driven more by the patient’s age, comorbidities, and neurological status than by factors within the surgeon’s control. While this study is unlikely to change clinical practice, it adds more data to the literature on this topic and lends strong support to treating these fractures aggressively with long posterior constructs.

 

Please read Dr. Robinson’s article in the February 15 issue. Does this change how view extension-distraction injuries in the ankylosed spine? Let us know by leaving a comment on The Spine Blog.

 

Adam Pearson, MD, MS

Associate Web Editor


Friday, February 20, 2015

The treatment of symptomatic lumbar spondylolysis in young adults is challenging. For the minority who fail to improve despite efforts at non-operative treatment, surgical options include fusion and direct pars repair. Neither option is particularly appealing for a patient in their twenties. While fusion is a relatively reliable treatment option for patients in whom the pars defect is the clear pain generator, it alters their lumbar mechanics and puts them at risk for adjacent segment disease over the course of their life. Direct pars repair, which can be successful in the pediatric population, has a checkered history in adult patients due to high rates of non-union. However, there has never been a high quality prospective study evaluating direct pars repair in adults that used modern outcome measures and imaging. As such, Dr. Lee and his colleagues from Korea prospectively evaluated the results of direct pars repair in 47 predominantly male soldiers aged 20-25. They evaluated back pain visual analog scale (VAS), Oswestry Disability Index (ODI), patient satisfaction, and fusion status based on CT scan with one year follow-up. The back pain VAS improved from 8.4 to 3.7, and ODI improved from 25.3 to 4.7. However, only 53% of patients reported significant or complete relief, with the remainder reporting slight or no improvement. Only 55% were found to have successfully fused the pars defects at one year, though fusion status was not related to outcomes. Based on these results, the authors suggested direct pars repair in young adults led to “unsatisfactory outcomes”.

 

The results of this study should be considered mixed, and whether they are satisfactory or not depends on one’s perspective. A twenty point improvement on the ODI with final average ODI scores of less than 5 would be considered a very successful result in most studies of lumbar spine surgery. It is somewhat surprising that only 53% were satisfied with such a result. This cohort was much different from your average back pain population in that they were much younger, more active, and likely expected a higher level of function than the middle-aged sedentary individual with chronic low back pain. As such, the patients in the current study may have found any persistent pain or disability unsatisfactory. Their relatively low baseline ODI scores may reflect their high expectations in that they elected to undergo surgery at a level of disability that may not have prompted surgery in a lower demand population. While this study aimed to determine if direct pars repair was effective in this population, it really did not answer the question. Longer follow-up may be revealing as the patients with non-union could have developed hardware loosening or failure with symptom recurrence or they may have gone onto stable, fibrous unions. The real question is whether direct pars repair or fusion leads to better outcomes in young adults, and this is unlikely to be answered until an RCT with long-term follow-up is performed comparing the two techniques in this population. While the authors suggested such a study was not possible due to difficulty recruiting enough patients, they managed to recruit almost 50 patients in ten months. It is hard to imagine many other institutions being able to recruit more young adult spondylolysis patients, so maybe this is the group to do such a study.

 

Please read Dr. Lee’s article on this topic in the February 15 issue. Does this change how you view the treatment of lumbar spondylolysis in the young adult? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor


Friday, February 13, 2015

One important goal of clinical research is to predict treatment outcomes based on individual patient characteristics. This allows patients to have more realistic expectations and to compare likely outcomes between different treatment options. Many patient characteristics have been shown to predict worse outcomes following spine surgery, including narcotic pain medication use, lower socioeconomic status, medical and psychological comorbidities, and receiving worker’s compensation. However, most of these same factors also predict worse non-operative outcomes, so patients with these characteristics still have a similar benefit from surgery relative to non-operative treatment.1 In an effort to evaluate another potential predictor of surgical outcomes in spinal stenosis patients, Dr. Kim and his colleagues from Korea compared surgical outcomes between stenosis patients stratified by their score on the Pain Sensitivity Questionnaire (PSQ). They stratified 171 lumbar stenosis patients undergoing decompression with or without fusion into high and low pain sensitivity groups based on the mean PSQ for the cohort. The high PSQ group had worse baseline Oswestry Disability Index (ODI) and VAS back and leg pain scores. That group also included more women. Not surprisingly, the high PSQ group also had worse outcome scores at 12 months, though the 12 month change scores were similar for the two PSQ groups, indicating that the high PSQ patients benefited similarly from surgery as the low PSQ group.

 

The PSQ represents an attempt to quantify a somewhat vague quality that is likely related to characteristics such as catastrophizing and coping difficulty. All spine providers are familiar with this cluster of traits and generally see them as a gestalt, though the ability to quantify such factors has the potential to improve outcome prediction models. It comes as no surprise that reporting higher levels of pain for imagined stimuli on the PSQ is associated with reporting worse pain and disability on the ODI or VAS back and leg pain. What is not clear is whether or not patients who report greater pain sensitivity and worse pain and function actually experience greater pain or are simply prone to responding to questionnaires with answers reflecting greater degrees of distress. Since pain is a subjective phenomenon, it is likely not possible to answer this question. As such, absolute ODI and VAS scores are less useful measures of surgical success, and change scores are probably a better outcome measure. Like many patient characteristics, PSQ did not predict change scores. Since non-operative outcomes were not measured, calculation of the treatment effect of surgery (i.e. the difference in the change scores between surgical and non-operative treatment) was not possible.  Hopefully future research will evaluate the association between PSQ and both surgical and non-operative outcomes so that it can be assessed as a predictor of treatment effect. The current paper suggests that patients with high pain sensitivity will likely see similar degrees of surgical improvement as patients with lower levels of pain sensitivity, though, since they start with higher reported levels of pain and disability, they will likely have worse absolute levels of pain and disability following surgery. This study and other literature suggest that surgery should still be offered to these patients, though they should have realistic expectations about their long-term post-operative outcomes.

 

Please read Dr. Kim’s article on this topic in the February 1 issue. Does it change how you view surgical outcome prediction in spinal stenosis? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 

REFERENCE

1.            Pearson A, Lurie J, Tosteson T, Zhao W, Abdu W, Weinstein JN. Who should have surgery for spinal stenosis? Treatment effect predictors in SPORT. Spine 2012;37:1791-802.

 


Friday, February 06, 2015

The role of MRI in predicting outcomes in cervical spondylotic myelopathy (CSM) is poorly understood. Some studies have suggested that the presence of cord signal changes on T1 or T2 imaging and worse degrees of cord compression portend less improvement with surgery, while others have reported that significant improvement is possible even in the presence of such findings.1 Clinical factors, especially baseline functional status as measured by the mJOA score, have been shown to be relatively strong predictors of surgical outcomes.2 Given the conflicting data regarding the utility of MRI findings in predicting surgical outcomes in CSM, Dr. Nouri and colleagues evaluated the relationships between MRI findings and surgical outcomes in 102 CSM patients. They dichotomized 6 month surgical outcomes into those with mild residual symptoms (mJOA score ≥ 16) and significant impairment (mJOA < 16). Not surprisingly, baseline mJOA score was the strongest predictor in the univariate analysis. The authors evaluated many MRI characteristics, but only T2 hyperintensity area on sagittal and axial images and the maximum degree of cord compression were significantly associated with worse outcomes. They went onto create a multivariate model that included baseline mJOA score, T1 hypointensity, and maximum cord compression and found that to be a reasonably good predictor of their dichotomized outcome.

 

This study does a nice job demonstrating that MRI findings do predict CSM surgical outcomes to some degree but that baseline functional status is a much stronger predictor. These results are not surprising as cord signal changes and maximum cord compression are both related to baseline functional status. While there have been some contradictory findings regarding the role of cord signal changes in predicting outcomes, this is likely related to how outcomes are defined. If the outcome measure is change in mJOA score from baseline, patients with worse baseline mJOA scores, cord signal changes, and significant cord compression can frequently improve more than patients with mild disease who are limited by the ceiling effect of the mJOA scale. As such, studies that looked at change scores did not find that cord signal changes and severe cord compression predicted worse outcomes. Studies like the current study, which looked at the absolute post-operative mJOA score, have found worse outcomes related to cord signal change and cord compression since patients with these characteristics tend to have worse baseline mJOA scores and continue to have worse post-operative scores compared to patients with less severe myelopathy. This study allows surgeons to have more informed discussions with CSM patients so that expectations about post-operative function can be more accurate. However, it seems unlikely that specific MRI findings are going to significantly affect surgical decision making once the diagnosis of CSM is made.

 

Adam Pearson, MD, MS

Associate Web Editor

 

 

REFERENCE

 

1.            Tetreault LA, Dettori JR, Wilson JR, et al. Systematic review of magnetic resonance imaging characteristics that affect treatment decision making and predict clinical outcome in patients with cervical spondylotic myelopathy. Spine (Phila Pa 1976) 2013;38:S89-110.

2.            Tetreault LA, Kopjar B, Vaccaro A, et al. A clinical prediction model to determine outcomes in patients with cervical spondylotic myelopathy undergoing surgical treatment: data from the prospective, multi-center AOSpine North America study. J Bone Joint Surg Am 2013;95:1659-66.

 


Friday, January 30, 2015

While the accuracy of administrative billing databases may not seem like the most exciting spine-related topic, the proliferation of literature based on these databases makes it relevant. Level 1 RCTs will always represent the gold-standard in evidence-based medicine, however, these studies are very expensive to perform and usually answer only one specific question in a highly selected population. As such, spine researchers have turned to administrative billing databases in order to capture large numbers of “real-world” patients at relatively low costs. In order for the results of such analyses to be valid, the coding needs to accurately reflect the clinical situation. To address this question of the accuracy administrative billing data, Dr. McGuire and his colleagues from Boston used an administrative coding algorithm to classify surgical indication and technique and then compared the findings of the algorithm to the indications and technique documented in the medical record. They identified 477 patients who had undergone lumbar spine surgery at one institution and classified the indication for surgery as degenerative disk disease, disk herniation, spinal stenosis, spondylolisthesis, or scoliosis. Surgical technique was classified as fusion or no fusion, and fusion patients were subclassifed as combined anterior-posterior vs. single approach, instrumented vs. uninstrumented, and one or two level vs. three or more level fusion. Using the chart review as the gold standard, they found the coding algorithm had a sensitivity and specificity of over 80% for every diagnosis other than spinal stenosis (sensitivity 33%) and degenerative disk disease (sensitivity 72%).  The accuracy was excellent (sensitivity/specificity > 95%) for determining if a fusion was performed and for surgical approach (i.e. combined AP vs. single approach). However, the accuracy dropped off substantially in identifying the use of instrumentation and number of levels fused.

 

This is a helpful study as it lets the reader get a sense of what aspects of administrative database studies are likely valid and which ones should be questioned. The algorithm was relatively accurate for diagnosis other than for spinal stenosis. This is in contrast to a similar study that evaluated the algorithm compared to the diagnosis assigned to patients in the Spine Outcomes Research Trial (SPORT), which found a sensitivity of 88% for spinal stenosis.1 The cause of the discrepancy between the two studies is not clear, but the algorithm used a “hierarchical” approach that assumed fusion should be relatively uncommon for spinal stenosis. While this held true for SPORT, in which 11% of stenosis patients underwent fusion,2 58% of the stenosis cohort in the current study underwent fusion. Another possibility is that patients that were documented as having stenosis in the chart actually had listhesis or scoliosis that could have been detected had the radiographs been reviewed. The algorithm was much more accurate in assigning a diagnosis to spondylolisthesis or scoliosis patients, where the hierarchical model assumed that fusion would be performed on most of these patients. The poor specificity in determining the use of instrumentation was surprising. There are straightforward CPT codes for lumbar instrumentation, and one would assume that these would be coded accurately. However, only 28 fusion patients in this cohort underwent uninstrumented fusion, and the algorithm inappropriately classified 12 of these patients as instrumented cases. It is possible that the low numbers involved make this finding less robust. The poor accuracy for capturing multilevel fusions is also surprising given that CPT codes for numbers of levels fused are also unambiguous. It is possible that the use of ICD-9 codes, which are less specific, may have reduced the accuracy. This paper indicates that the accuracy of administrative billing databases varies according to what is being coded. The discrepancy with the findings of the study using the SPORT data also indicates that coding is a local phenomenon, and the accuracy and precision of coding likely varies substantially across hospitals. This study reminds us to be cautious when evaluating administrative database studies and echoes concerned voiced previously about the accuracy of ICD-9 coding.3

 

Please read Dr. McGuire’s study in the January 15 issue. Does this article change how you view papers based on administrative billing data? Let us know by leaving a comment on The Spine Blog.

 

Adam Pearson, MD, MS

Associate Web Editor

 

REFERNCES

1.            Martin BI, Lurie JD, Tosteson AN, et al. Indications for spine surgery: validation of an administrative coding algorithm to classify degenerative diagnoses. Spine (Phila Pa 1976) 2014;39:769-79.

2.            Weinstein JN, Tosteson TD, Lurie JD, et al. Surgical versus nonsurgical therapy for lumbar spinal stenosis. The New England journal of medicine 2008;358:794-810.

3.            Golinvaux NS, Bohl DD, Basques BA, Fu MC, Gardner EC, Grauer JN. Limitations of administrative databases in spine research: a study in obesity. Spine J 2014;14:2923-8.

 

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.