The Spine Blog

Friday, October 13, 2017

Spine clinicians strive to come to specific diagnoses down to the nerve root level based on a history, physical exam, and imaging studies. At a practical level, spine surgeons need to determine if a nerve root is a pain generator in order to plan surgical treatment. The patient characterization of pain and numbness location and type of weakness plays a major role in diagnosing the specific nerve root(s) involved. While traditional dermatomal maps that adorn the walls of spine clinics suggest clear demarcations between the nerve roots, clinical experience and the literature would indicate that these dermatomes have significant overlap. In order to better define this, Dr. Rainville and colleagues performed an interesting study where they recruited 122 patients with pain radiating into the arm for whom cervical radiculopathy was high on the differential diagnosis. The patients then marked diagrams of the arm to report where they had pain and numbness and also answered questions about the type of weakness they had (i.e. no weakness, difficulty lifting arm overhead, difficulty pushing items, difficulty holding items, etc.). Spine clinicians then evaluated them and gave them a diagnosis based on a history, physical exam, and cervical MRI. Patients with non-spinal diagnoses, myelopathy or multilevel radiculopathy were excluded. This left 30 patients with C6 radiculopathy and 39 patients with C7 radiculopathy. Analyses of pain and numbness location and type of weakness demonstrated no statistically significant differences between the C6 and C7 radiculopathy patients. There were trends towards C7 patients being more likely to report pain in the posterior index finger and medial forearm and sensory symptoms in the posterior middle finger, though a minority of patients in either group reported symptoms in any of those specific regions.  The authors concluded that C6 and C7 radiculopathies cannot be reliably distinguished based on patient reported symptoms.

The authors should be congratulated for tackling a topic that many in the spine field may have assumed was settled based on anatomic studies decades ago. However, spine surgeons realize the practical difficulty faced when trying to determine if a specific root is contributing to radicular symptoms and needs to be surgically decompressed. This paper suggests that is not possible to do based on the location of pain and sensory symptoms reported by the patient. The authors did not include any data from the physical examination, though motor and sensory exams are very subjective and may not provide much more discriminatory data than the history. The authors also noted that the study may have been underpowered, but they pointed out that a study with more patients that generated a statistically significant difference of the magnitude observed in the current study would still have not allowed for differentiation between C6 and C7 radiculopathy as there was so much overlap between the groups. Spine clinicians should be relieved by this study as their difficulty in diagnosing cervical radiculopathy down to the nerve root level is likely more related to the overlap between the nerve roots than to their lack of clinical acumen. Spine surgeons should also take note and understand that differentiating between C6 and C7 radiculopathy based on symptom location is not possible, and surgery for patients with radicular symptoms radiating distally in the arm should address all areas of nerve compression in the lower cervical spine.

Please read Dr. Rainville’s article on this topic in the October 15 issue. Does this change how you view your ability to diagnose C6 versus C7 radiculopathy based on clinical findings? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor


Friday, October 6, 2017

Patients and spine surgeons have long sought out tools to predict outcomes following surgery in order to make more informed treatment decisions. In general, patient characteristics such as medical comorbidities, psychosocial problems, and being involved in worker’s compensation claims or litigation have been stronger predictors of outcomes than surgical factors such as fusion technique.1-4 In order to assess risk factors for poor outcomes following PLIF for degenerative spondylolisthesis and/or foraminal stenosis requiring complete facetectomy, Dr. Makino and colleagues from Japan evaluated 2 year outcomes for 100 consecutive patients undergoing one or two level PLIF. Their main outcome measure was effectiveness on the Japan Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), defined as an improvement of over 20 points or final score of over 90. This questionnaire evaluates five different domains (pain-related disorders, lumbar spine dysfunction, gait disturbance, social life dysfunction, and psychological disorders), with each domain scored 0-100, with 100 being the best possible score. Two-year effectiveness of surgery ranged from 31% on psychological disorders to 78% for gait dysfunction. In their multivariate analysis, the strongest predictor of ineffectiveness across most domains was increasing age. A post-operative decrease in lumbar lordosis predicted poor outcomes on pain-related disorders, social life dysfunction, and psychological disorders. Surgical factors such as increased number of fused levels, pseudarthrosis, and radiographic adjacent segment degeneration (ASD) predicted worse outcomes on lumbar spine dysfunction and gait disturbance.

The authors have done a nice analysis of risk factors for poor outcomes on the relatively new JOABPEQ, which has not been used in this type of study in the past. Most prior studies of risk factors for poor outcomes have used legacy instruments such as the SF-36, Oswestry Disability Index, and Roland Morris Disability Questionnaire. The major limitation of this study is that the authors only included age, sex, and body mass index as patient-related variables in their model. Characteristics such as medical comorbidities, psychosocial factors such as depression, educational attainment, and socioeconomic status, and work-related factors such as disability or litigation were not included. Given that these factors have been the strongest predictors of outcomes in prior studies, it is hard to interpret the results of this study. Age seems to be a predictor of surgical ineffectiveness, but that might be a function of the definition of effectiveness which includes patients who obtain a score of over 90. A prior study has shown that JOABPEQ scores decrease with age, so older patients likely had to improve more to reach this threshold for effectiveness.5 Finally, the number of patients in the subgroups analyzed likely became very small (i.e. there were only 22 patients in the non-effective group for pain-related disorders, and only 5 among them with a pseudarthrosis), making it underpowered to detect the effects of many variables. Despite the limitations of this paper, it does suggest that certain surgical factors such as multilevel fusion, post-operative loss of lumbar lordosis, pseudarthrosis, and radiographic ASD are associated with worse outcomes. However, it remains likely that the strongest drivers of outcomes are patient-related factors.

Please read Dr. Makino’s article in the October 1 issue. Does this change how you think about risk factors for failure following lumbar fusion? 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.            Ekman P, Moller H, Tullberg T, Neumann P, Hedlund R. Posterior lumbar interbody fusion versus posterolateral fusion in adult isthmic spondylolisthesis. Spine (Phila Pa 1976) 2007;32:2178-83.

3.            Pearson AM, Lurie JD, Tosteson TD, Zhao W, Abdu WA, Weinstein JN. Who should undergo surgery for degenerative spondylolisthesis? Treatment effect predictors in SPORT. Spine (Phila Pa 1976) 2013;38:1799-811.

4.            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.

5.            Hashizume H, Konno S, Takeshita K, et al. Japanese orthopaedic association back pain evaluation questionnaire (JOABPEQ) as an outcome measure for patients with low back pain: reference values in healthy volunteers. J Orthop Sci 2015;20:264-80.

 


Friday, September 29, 2017

The appropriate magnitude of surgery for adult deformity cases is difficult to define using objective criteria, and the decision is typically made subjectively based on surgeon judgment and personal preference. The literature to help make the decision is quite weak, probably due to the high level of heterogeneity in patient and deformity characteristics that makes the topic very difficult to study. One of the major questions in this field is whether or not a short segment fusion accompanying decompression of the stenotic levels within the curve without complete curve stabilization puts the patient at increased risk for curve progression at the adjacent levels with need for revision surgery. In the elderly population, smaller magnitude surgery has obvious advantages in terms of decreased morbidity, but this must be balanced against the possibility for worse clinical outcomes and a higher rate of revision surgery. In order to better understand this topic, Dr. Lee and colleagues from Korea performed a meta-analysis comparing degree of curve correction, Oswestry Disability Index (ODI) scores, and complications between “balanced” adult deformity patients undergoing either short (1 or 2 level) or long (3 or more level) fusions. Complications included reoperation for adjacent segment degeneration, pseudarthrosis, or sagittal balance correction. They identified six observational studies that compared these two groups and included 202 short fusion patients and 160 long fusion patients who were generally followed for 2 years or more. The average age was 65 in the short fusion group and 67 in the long fusion group. At baseline, the long fusion patients tended to have greater coronal Cobb angles and less lumbar lordosis, though these differences were not statistically significant. Final follow-up Cobb angles, coronal imbalance measured by C7 plumb line, and ODI scores were not different between the two groups. Not surprisingly, blood loss and operative times were significantly higher in the long fusion group. The re-operation rate for the mechanical issues noted above was over twice as high for the long fusion group (12% vs. 5%).

 

The authors have done a nice job summarizing the literature that exists on this topic, though the quality of the available literature is low. None of the studies were randomized, and there were substantial differences between the groups at baseline on the measured variables. There were likely major differences in the important unmeasured variables as well including patient comorbidities, flexibility of curve, bone quality, extent of stenosis, and sagittal parameters. Overall, the patients saw major improvements in their ODI scores, from the 70s pre-operatively to the 30s post-operatively, indicating that surgery for this problem was generally effective. Given that these were not randomized studies, this implies that surgeons were making reasonable decisions about the magnitude of surgery. One can conclude that the surgeons in these studies were able to select the patients in whom short segment fixation tended to be successful. There may well have been patients in the long fusion group who could have been managed successfully with short fusions, but this study design does not allow for that question to be answered. The reoperation rate for mechanical complications was more than twice as high in the long fusion group, suggesting that short segment fusion does not increase the need for reoperation. While this paper did not stratify by type of mechanical complication, the increased rate of reoperation in long fusions is likely due to higher rates of pseudarthrosis and proximal junctional failure. This paper does not provide any meaningful guidance to the deformity surgeon trying to decide on fusion length in an individual patient, though it does suggest that short segment fusion without complete curve correction is reasonable in a select group. Defining that group will remain up to the surgeon’s judgment until there is more data to inform the decision.

Please read Dr. Lee’s paper on this topic in the October 1 issue. Does this change how you consider the decision about fusion length in the adult deformity population? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor


Friday, September 22, 2017

The opioid crisis has received extensive coverage in the lay press and medical literature, and a large number of patients with opioid abuse problems were initially exposed to narcotic pain medication as treatment for back pain. Many lumbar fusion patients are taking opioids pre-operatively, and many of these patients fail to wean off narcotics following surgery. In order to determine risk factors for long-term opioid use following lumbar fusion, Dr. Connolly and colleagues from Texas used a large commercial insurance administrative billing database and evaluated demographic characteristics, comorbidities, fusion approach, and duration of pre-operative opioid use as risk factors for long-term post-operative narcotic use (defined as prescriptions written for more than 365 days of narcotics in the two year post-operative period). They identified over 8,000 adult patients under age 65 who underwent fusion from 2009 to 2012 and who had two years of pre- and post-operative billing data. Overall, approximately 30% of fusion patients used long-term opioids post-operatively. The strongest predictor of long-term post-operative narcotic use was duration of pre-operative narcotic use. Compared to patients who had not received prescriptions for opioids pre-operatively, those who had received 1-22 days of pre-operative opioids had over twice the odds of long-term use (5% vs. 2%), and those who had taken opioids for over 250 days pre-operatively had an odds ratio of 220 relative to the opioid naïve patients (84% vs. 2%). There was a clear dose-response curve, with increasing duration of pre-operative use associated with increasing risk of long-term post-operative use. Depression (OR= 1.4) and undergoing a revision fusion operation (OR=1.3) increased the risk of long-term use modestly, while those undergoing anterior fusion were 21% less likely to use opioids in the long-term compared to those undergoing posterior fusion.

The results of this study come as no surprise to practicing spine surgeons and are consistent with the literature. It is rare for a patient who has been on long-term opioids pre-operatively to come off of these medications after fusion surgery. The fact that only 2% of the opioid naïve patients and 5% of those on narcotics for under 3 weeks pre-operatively went onto long-term use is reassuring and suggests that spine surgery itself is a relatively uncommon route for patients to develop problems with opioid dependence. The limitations of this study are those associated with any large administrative database study, namely that some of the billing data may be unreliable and the database does not capture sufficient detail on factors such as psychosocial comorbidities. The clear dose response relationship between pre-operative duration of opioid use and long-term post-operative use indicates that these data are likely reliable. Specific psychosocial factors such as work status, personal or family history of substance abuse, educational attainment, and coping ability may play a stronger role in long-term opioid dependence than a coded diagnosis of depression, but these data are not available in billing databases.   This paper suggests that long-term treatment with opioids pre-operatively is the main driver of long-term opioid use post-operatively, so efforts to avoid treating low back pain with narcotics are essential to addressing this problem. The pendulum seems to be swinging in this direction, and hopefully physicians will stop treating chronic low back pain with opioid medication.

Please read Dr. Connolly’s article on this topic in the September 15 issue. Does this change how you view opioid use following spine surgery? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor


Friday, September 15, 2017

Debate about the need for fusion in degenerative spondylolisthesis (DS) has continued since Herkowitz and Kurz’s seminal 1991 paper reporting better outcomes in DS patients who underwent decompression and fusion compared to decompression alone.1 Two recent RCTs randomized DS patients to decompression and fusion or decompression alone and reached essentially opposite conclusions.  The Swedish study found no differences in patient reported outcomes or reoperation rates, while the American study reported significantly better patient reported outcomes and a lower reoperation rate in the decompression and fusion group.2,3 In order to add more data on this topic to the literature, Dr. Ulrich and colleagues from Switzerland used data from the Lumbar Stenosis Outcome Study to compare outcomes between DS patients treated with decompression and fusion and decompression alone.  They identified a cohort of 131 DS patients who had undergone surgery and had follow-up for at least 12 months (46 had outcomes out to 3 years). The decision to perform fusion in addition to decompression was made by the treating surgeon, and approximately 1/3 of patients underwent a posterolateral instrumented fusion with or without interbody fusion. The fusion patients were significantly younger and more likely to undergo a single level procedure. Unadjusted analyses revealed significantly more improvement on the Spinal Stenosis Measure for the fusion group, but after adjustment for baseline characteristics, the differences were no longer significant. The reoperation rate was 4.3% (n=2) in the fusion group and 9.4% (n=9) in the decompression only group. The vast majority of reoperations (7/9) in the decompression alone group were for restenosis at the index level.

This paper adds some interesting data to the debate about the role of fusion in DS. However, the limitations of a small, non-randomized study need to be considered before drawing any strong conclusions. There were major differences in baseline characteristics in the two cohorts, namely that the decompression only patients were older and had more multilevel disease. The authors presented no data about radiographic characteristics like disk height, facet alignment relative to the sagittal and coronal planes, motion on flexion-extension x-rays, and degree of disk degeneration that may have influenced surgeons’ decision making about the need to perform fusion. As such, there were likely many unmeasured confounders that could not be taken into account with statistical analysis. Additionally, very few patients reached 3 year follow-up, and the precision of models controlling for multiple covariates decreases as the number of patients decreases. Overall, this paper suggests that many DS patients do quite well with a decompression alone, and it is possible that the surgeons may have been able to select those patients based on factors not reported in this paper. Similarly, certain patients may do better with a fusion, and performing a fusion seems to reduce the risk of reoperation at the index level. At this point, the scientific literature does not provide guidance on how to select which DS patients will benefit from fusion in addition to decompression, and surgeons will continue to rely on their clinical judgment to make this decision. In the United States, most surgeons continue to perform decompression and fusion for DS, possibly due to the desire to avoid difficult revision surgery at a previously decompressed level. Hopefully future research will provide evidence to help surgeons select the right operation for DS patients based on their individual characteristics.

Please read Dr. Ulrich’s article on this topic in the September 15 issue. Does this change how you view the need for fusion in DS? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

REFERENCES

1.            Herkowitz HN, Kurz LT. Degenerative lumbar spondylolisthesis with spinal stenosis. A prospective study comparing decompression with decompression and intertransverse process arthrodesis. The Journal of bone and joint surgery 1991;73:802-8.

2.            Forsth P, Olafsson G, Carlsson T, et al. A Randomized, Controlled Trial of Fusion Surgery for Lumbar Spinal Stenosis. The New England journal of medicine 2016;374:1413-23.

3.            Ghogawala Z, Dziura J, Butler WE, et al. Laminectomy plus Fusion versus Laminectomy Alone for Lumbar Spondylolisthesis. The New England journal of medicine 2016;374:1424-34.