The Spine Blog

Friday, March 24, 2017

There is an established literature demonstrating that high volume surgeons and hospitals have better outcomes, fewer complications, and lower costs than low volume surgical programs. 1,2 However, data on the relationship between surgeon volume and outcomes in cervical spine surgery are scant. As such, Dr. Basques and colleagues from Chicago used the National Inpatient Sample (NIS) from 2003-2009 to evaluate the association between surgeon volume and complications and costs for patients undergoing anterior cervical fusion (ACF). They divided surgeons into low (25th percentile or less, under 6 cases/year), medium (25th-74th percentile, 6-66 cases/year), and high (75th percentile or higher, more than 66 cases/year) volume cohorts. The low volume surgeons’ patients were older, more likely to be on Medicare or Medicaid, had a higher proportion of males, and a higher comorbidity burden compared to the medium and high volume surgeons. Using a statistical model controlling for age, sex, comorbidity burden, and insurance status, they found that low volume surgeons had an over 3-fold higher rate of any inpatient complication, while high volume surgeons had a 30% lower complication rate compared to the medium volume cohort. Length of stay was over 2 days longer in the low volume group and 0.3 days shorter in the high volume group. Inpatient costs were over $4,500 higher in the low volume group and $1,200 less for the high volume group. Based on these data, the authors concluded that the typical surgeon volume-outcomes relationship held true in ACF.

The results of this study come as no surprise given the consistent findings across disciplines that increased surgeon and hospital volumes result in better outcomes with decreased complications and lower costs. While this study provides a very high level view of the topic, the important causative details that underlie this relationship remain obscure with such a study design.  One of the major limitations of the NIS is that only inpatient complications for the index admission are recorded, and these complications are oftentimes not the most relevant for the procedure under consideration. In this study, included complications included death, pneumonia, acute kidney injury, urinary tract infection, MI, sepsis, surgical site infection, and durotomy. Given that the overall complication rate including all of these was only 1.3%, the rate of any individual complication was clearly very low. The inpatient complications more germane to ACF such as neurological injury, re-operation, esophageal injury, vascular injury, and dysphagia were not recorded, and complications seen most frequently after discharge including readmission, hardware failure, surgical site infection, pseudarthrosis, and adjacent segment disease could not be captured with the NIS. Another limitation was the failure to control for hospital volume, which likely played a greater role in affecting the outcomes measured in this study than surgeon volume. Finally, the study did not control for different diagnoses, so non-elective cases performed for trauma, infection, or tumor were lumped together with the more common degenerative cases. This study makes a reasonably good case that higher volume surgeons have fewer complications and are more efficient in resource utilization than lower volume surgeons performing ACF. However, we still do not know exactly why this relationship holds true or how to transfer some of the effective practices of high volume surgeons to their low and medium volume counterparts.

Please read Dr. Basques’s article on this topic in the March 15 issue. Do you believe the relationship between surgeon volume and outcomes holds true in your institution? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor



1.            Davies JM, Ozpinar A, Lawton MT. Volume-outcome relationships in neurosurgery. Neurosurg Clin N Am 2015;26:207-18, viii.

2.            Lau RL, Perruccio AV, Gandhi R, Mahomed NN. The role of surgeon volume on patient outcome in total knee arthroplasty: a systematic review of the literature. BMC Musculoskelet Disord 2012;13:250.



Friday, March 17, 2017

Neuromonitoring (NM) is considered the standard of care for deformity correction surgery, however, its role in routine anterior cervical spine surgery for degenerative conditions is less clear. A recent article published in Spine by Ajiboye et al. based on the Pearl Diver database demonstrated a decrease in the rate of NM use during ACDF from over 20% in 2007 to under 5% in 2014.1 This study also reported no differences in the rate of neurological injury between the monitored and unmonitored groups. In the March 15 issue, this group published a follow-up article in which they performed a meta-analysis in an attempt to determine the test characteristics of NM for anterior cervical surgery and whether it decreased the rate of intra-operative neurological injury. They identified 10 studies that evaluated NM use in anterior cervical surgery. Not surprisingly, the included studies were primarily Level IV evidence, with two retrospective cohort studies graded Level III. The studies were also quite heterogeneous in terms of neuromonitoring technique (i.e. SSEPs vs. MEPS vs. both), thresholds for defining a positive intra-operative alarm, and the types of patients (i.e. radiculopathy, myelopathy, trauma, tumor, infection) and procedures (i.e. ACDF, corpectomy or both) included. Only two of the studies compared the rate of neurological injury between the monitored and unmonitored groups. Despite these limitations, the authors combined the data for analysis, which included over 26,000 patients (though a single database study included over 22,000 of these). The overall rate of perioperative neurological injury was 0.19%, with a rate of 0.64% if each study was weighted equally. The studies that included only ACDF had a lower neurological injury rate (0.19%) as compared to those that included corpectomies as well (1%), though the large database study with over 22,000 patients included only ACDF patients and had one of the lowest neurological injury rates (0.12%), which likely pulled down the average for the ACDF-only studies. There were no significant differences in the rate of neurological injury for the monitored vs. non-monitored groups. The overall sensitivity of NM was 71%, and the positive predictive value was only 24%, indicating a false positive rate of 76%.


The authors did a nice job combining the available evidence on this topic, despite it being of relatively low quality and of a heterogeneous nature. The strength of a meta-analysis is limited by the quality of the included studies, which is the most significant limitation of the current study. The heterogeneity in terms of NM technique, alarm threshold, and patient and procedure characteristics also make it difficult to interpret the data. Due to the fortunately low rate of intra-operative neurological injury, this is a very difficult topic to study as huge numbers of patients are needed to sufficiently power a study. The large database study included in this meta-analysis represents one way to address the power issue, however, the ability of such a study to capture every case of neurological injury is questionable given that study’s very low rate of neurological injury. Additionally, it is unclear how each study defined neurological injury, so it is not possible to determine the rate of major spinal cord injury or less concerning neurological injuries such as C5 palsy. While this study did not address it, the major question regarding NM use for routine anterior cervical surgery is whether or not it can actually alert the surgeon to a reversible neurological insult. Most of the neurological injuries that occur intra-operatively are probably not reversible, so alerting the surgeon to such a problem intra-operatively does not change the outcome. The current study is probably not definitive in demonstrating the lack of efficacy of neuromonitoring for routine anterior cervical surgery, however, it does support the current trend in the spine surgery community of moving away from NM for these cases.

Please read Dr. Ajiboye’s article in the March 15 issue. Does this change how you view the use of NM in anterior cervical surgery? Let us know by leaving a comment on The Spine Blog.


Adam Pearson, MD, MS

Associate Web Editor



1.            Ajiboye RM, D'Oro A, Ashana AO, et al. Routine Use of Intraoperative Neuromonitoring During ACDFs for the Treatment of Spondylotic Myelopathy and Radiculopathy Is Questionable: A Review of 15,395 Cases. Spine (Phila Pa 1976) 2017;42:14-9.


Friday, March 10, 2017

Non-physician providers are playing an increasingly important role across healthcare, and spine care is no exception. In fact, spine care may be an excellent field in which to utilize non-physician providers (i.e. physician assistants, nurse practitioners, physical therapists, etc.) given that the majority of spine patients do not require surgical treatment. There are many motivations to employ non-physicians in a spine practice, namely to reduce wait times to evaluation and to increase the efficiency of a surgeon’s time in clinic such that they are seeing primarily patients with surgical pathology. While healthcare system and clinic efficiency may be improved with non-physician providers, it is unclear if patients are willing to see them instead of a spine surgeon when determining the appropriateness of surgery for their case. Given this uncertainty, Rempel et al. surveyed 80 Canadian spine patients referred for surgical evaluation to evaluate their opinions about the role of non-physician providers in the care of their spine problem. Over 85% of patients completed the survey, and they were relatively neutral regarding their willingness to be evaluated by a non-physician. On a 0-4 scale judging their willingness to see a non-physician, the median response was 2, and 45% answered 3 or 4. Only 11.2% answered 0, indicating an absolute unwillingness to see a non-physician. However, 70% responded they would want a second opinion from the surgeon if the non-physician concluded that surgery was not indicated. 45% of patients were willing to pay out of pocket to see a non-physician if they could be evaluated within 2 weeks of referral. Canadians are apparently accustomed to long wait times to see specialists, with 73% being willing to wait up to 3 months for spine surgeon evaluation. Written comments on the survey indicated a willingness to see non-physicians if it could reduce the waiting time for evaluation, but many patients were concerned that the non-physician might evaluate their case differently than a surgeon.

This is an important paper as it analyzes a question facing most spine practices at this time. My practice, like many American spine practices, utilizes midlevel providers (i.e. physician assistants, nurse practitioners) to evaluate patients referred to us. However, some patients find this dissatisfying and would be prefer to see a surgeon during their evaluation. Patient satisfaction needs to be weighed against clinic efficiency, and, given that over 90% of spine patients do not meet indications for surgery, spine surgeon evaluation of an unscreened population will result in the surgeon evaluating primarily patients who need non-operative care. In Canada, where spine surgeons are in short supply and waiting lists are long, non-physician providers could help reduce this wait time and allow for surgical patients to be treated more expeditiously. In the United States, where there is no lack of spine surgeons, such a model would increase efficiency of the spine surgeon in clinic. It could also improve patient satisfaction as the surgeon could potentially spend more time with patients that meet the indications for surgery, while non-operative patients can avoid an unnecessary evaluation by a surgeon. The results of this paper suggest that Canadian patients are willing to see non-physician providers if it helps them access the system faster. It is unclear if the results generalize to the United States, where access to spine surgeons is much quicker. The authors suggest an RCT to determine the effectiveness of a model in which spine patients are initially evaluated by a non-physician. While this would yield interesting results, these models are already in place and seem to be here to stay. The key going forward is to make sure that the non-physicians are well-trained and provide the same or better quality evaluation and patient experience. If that is the case, patients will probably increase their enthusiasm for non-physician providers.

What role do non-physician providers play in your practice? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

Friday, March 3, 2017

The association between smoking and surgical complications has been well-established across many surgical disciplines. A recent article in the Journal of Bone and Joint Surgery by Tischler and colleagues from Thomas Jefferson University demonstrated an 82% increased risk of re-operation for infection following total joint arthroplasty (unadjusted rates of 1.2% vs. 0.6%).1 This study included over 15,000 patients who had undergone arthroplasty at a single institution and used multivariate statistical techniques to control for potential confounders. The publication of this study was the impetus for a review of the spine literature on the topic. In the April 2016 issue of Spine, Dr. Martin and colleagues from Iowa published a retrospective cohort study of over 35,000 lumbar surgery patients based on the National Surgery Quality Improvement Project (NSQIP) database.2 Approximately 22% of patients in this study were current smokers, and this group had a 27% increased risk of wound complications compared to non-smokers after controlling for potential confounders. There was a similar trend for former smokers, but due to the small number of patients who identified themselves as such (about 500, or less than 2% of the patients), these differences were not significant. Overall, these findings echo those of the recent arthroplasty study and suggest that smokers have a significantly higher rate of wound and infectious complications.

While the deleterious effect of smoking on wound healing may seem clear, the spine literature is somewhat varied in its findings about the association between smoking and wound complications. Multiple studies have reported no association between smoking and wound healing or infectious complications following spine surgery.3,4 However, these studies tended to be underpowered or controlled for comorbidities associated with smoking (i.e. heart disease, COPD, vascular disease, etc.) The overall surgical literature does suggest a fairly strong association between smoking and wound healing complications, and it seems that the same pathophysiology affecting wound healing applies in a similar fashion across all surgical disciplines. In addition to complications such as surgical site infection and pseudarthrosis, smoking also appears to be associated with worse patient reported outcomes. The Spine Patient Outcomes Research Trial (SPORT) disk herniation and spinal stenosis studies demonstrated that smokers had worse patient reported outcomes after both surgical and non-operative treatment.5,6 While it is clear that smoking has a negative effect on outcomes following spine surgery, what is less clear is the effect of smoking cessation. Most studies have shown intermediate outcomes for former smokers when compared with never smokers and current smokers, so it seems likely that pre-operative smoking cessation does have at least some benefit. Based on the data currently available, it seems reasonable to suggest smoking cessation prior to lumbar surgery. A very large RCT on the topic would be required to definitively answer the question, and it is unclear if such a study will be undertaken.

Do these articles change how you treat smokers considering spine surgery? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor



1.            Tischler EH, Matsen Ko L, Chen AF, Maltenfort MG, Schroeder J, Austin MS. Smoking Increases the Rate of Reoperation for Infection within 90 Days After Primary Total Joint Arthroplasty. J Bone Joint Surg Am 2017;99:295-304.

2.            Martin CT, Gao Y, Duchman KR, Pugely AJ. The Impact of Current Smoking and Smoking Cessation on Short-Term Morbidity Risk After Lumbar Spine Surgery. Spine (Phila Pa 1976) 2016;41:577-84.

3.            Bydon M, De la Garza-Ramos R, Abt NB, et al. Impact of smoking on complication and pseudarthrosis rates after single- and 2-level posterolateral fusion of the lumbar spine. Spine (Phila Pa 1976) 2014;39:1765-70.

4.            Seicean A, Seicean S, Alan N, et al. Effect of smoking on the perioperative outcomes of patients who undergo elective spine surgery. Spine (Phila Pa 1976) 2013;38:1294-302.

5.            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.

6.            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.


Sunday, February 26, 2017

Cervical disc arthroplasty (CDA) has been available for over a decade, with short and medium term results suggesting similar patient reported outcomes compared to anterior cervical discectomy and fusion (ACDF), with the possible advantage of a lower reoperation rate. Investigators have continued to follow patients from the original FDA IDE trials, and 10 year follow-up data is now becoming available. Sasso et al. reported the 10 year results of the RCT comparing single level CDA to ACDF in 47 patients treated at a single site as a part of the Bryan CDA IDE trial. At 10 years, 86% of the CDA patients and 92% of the ACDF patients were available for follow-up. The CDA group had significantly lower Neck Disability Index (NDI) scores at 10 years (8 vs. 15), though the VAS arm and neck pain scores were similar. The 10 year reoperation rate was 9% in the CDA group as compared to 32% in the ACDF group (p=0.06). All reoperations were for pathology remote from the index surgical site (i.e. no reoperations for index level pseudarthrosis or hardware failure). A formal radiographic or clinical analysis of adjacent segment degeneration (ASD) was not performed.

The authors should be congratulated for presenting longer-term outcomes for RCT data on cervical CDA. Short and medium term data have been promising, though the more pressing concerns relate to long-term outcomes, including ASD and CDA mechanical failure. This study did not include a formal radiographic or clinical analysis of ASD, though the reoperations were essentially all for ASD (either at an adjacent or more remote level), with a trend towards more reoperations in the ACDF group. Reoperation is a complex outcome, as the choice to reoperate is based on surgeon and patient preference. Since the surgeon and patient were not blinded to treatment received, bias could affect this outcome. One of the most reassuring aspects of the current study was that no CDA patients underwent reoperation for device failure, indicating that these devices likely have a relatively long lifespan. Given that CDA tends to be recommended for relatively young patients with minimal bony deformity, long-term durability needs to be determined. This study adds to the evidence suggesting that CDA has similar long-term outcomes as ACDF, with the possible advantage of a decreased reoperation rate. Determining the best candidates for CDA remains challenging, and it may be that a relatively small number of patients with cervical degenerative conditions benefit from the technology. Hopefully the authors will continue to follow the current cohort to provide very long-term outcome data (i.e. > 20 years).

Please read the article by Sasso et al. in the February 15 issue. Does this change how you view long-term outcomes associated with CDA? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS
Associate Web Editor