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The Spine Blog

Friday, October 19, 2018

Thoracic hypokyphosis: An underappreciated compensatory mechanism

​The adult deformity literature has long-focused on compensatory mechanisms for the loss of lumbar lordosis and sagittal imbalance.  These mechanisms typically include pelvic retroversion and flexion at the hips and knees.  These changes help to keep the head centered over the pelvis.  Spinal deformity surgeons have also noted a tendency for thoracic hypokyphosis in patients with sagittal imbalance, though this mechanism has rarely been discussed in the literature.  Patients can effectively have a panspinal flat back deformity with loss of lumbar lordosis and decreased thoracic kyphosis yet maintain their sagittal vertical axis in the normal range.  In order to better understand this topic, Dr. Protopsaltis and colleagues in the International Spine Study Group evaluated 219 adult deformity patients in their registry who had undergone corrective surgery with fusion from the lower thoracic spine to the pelvis.  The mean age was 62, and approximately 70% were females.  The majority were undergoing revision surgery, and nearly 50% underwent a 3 column osteotomy.  The authors followed the patients out to 1 year with full–length radiographs and patient reported outcome measures.  They divided the patients into two groups, those with reciprocal kyphosis defined as an increase in kyphosis of the unfused thoracic spine of at least 15 degrees and at those with maintained thoracic alignment with less than a 15 degree change.  The demographic characteristics were not different between those 2 groups.  The reciprocal kyphosis group had a greater pelvic incidence minus lumbar lordosis mismatch at baseline and also less thoracic kyphosis.  The novel radiographic parameter evaluated by this paper was the expected thoracic kyphosis, which the authors calculated as the pelvic incidence - 20 degrees, based on prior radiographic investigations.  While the 2 groups had similar baseline expected thoracic kyphosis, the reciprocal kyphosis group had greater baseline thoracic kyphosis compensation, defined as the difference between expected thoracic kyphosis and baseline thoracic kyphosis (in other words, less thoracic kyphosis).  The reciprocal kyphosis group underwent greater deformity correction compared to the maintained thoracic alignment group, with a significantly greater change in pelvic incidence minus lumbar lordosis mismatch, pelvic tilt, sagittal vertical axis, and T1 pelvic angle.  At one year, the reciprocal kyphosis group had a markedly increased rate of proximal junctional kyphosis compared to the maintained thoracic alignment group, 66% versus 19%.  Overall sagittal alignment measured by sagittal vertical axis was not significantly different for the 2 groups.  There were also no differences in patient reported outcomes.

The authors have done a nice job continuing their work on understanding sagittal imbalance and its correction.  In some ways, thoracic compensation through hypokyphosis is a more obvious compensatory mechanism than pelvic retroversion given that spine surgeons frequently observe it on full-length radiographs, whereas pelvic retroversion can be more subtle.  It is not surprising that patients with baseline thoracic compensation are more likely to develop reciprocal kyphosis given that they, by definition, have more flexible thoracic spines.  Reciprocal kyphosis that does not go on to develop PJK does not appear to be harmful given that these patients maintained their overall alignment and had similar patient reported outcomes compared to those who maintained their thoracic alignment.  While those with reciprocal kyphosis had an increased risk of PJK compared to the maintained thoracic alignment, risk factors for PJK in the reciprocal kyphosis group were not well-defined.  More aggressive correction is a well-known risk factor for PJK, and avoiding this in those with baseline thoracic hypokyphosis might be helpful.  The authors suggested that those with baseline thoracic compensation might be candidates for fusion to the upper thoracic spine in order to prevent reciprocal kyphosis.  Given that this group had overall post-operative sagittal alignment in the appropriate range despite the reciprocal kyphosis implies that a similar degree of lumbar correction while preventing reciprocal kyphosis could result in overcorrection and increased risk of PJK in the upper thoracic spine.  Sagittal imbalance remains a challenging problem for which we still do not have a perfect solution.  A better understanding of the non-skeletal factors such as anterior soft tissue contractures and central neural mechanisms that contribute to sagittal imbalance and PJK may lead to more effective treatment in the future.

Please read Dr. Protopsaltis's article on this topic in the November 1 issue.  Does the concept of thoracic compensation improve your understanding of the sagittal imbalance?  Let us know by leaving a comment on The Spine Blog.


Adam Pearson, MD, MS

Associate Web Editor


Saturday, October 13, 2018

Management of Spine Trauma in the British System

All regional health systems have triage methods, either formal or informal, for triaging and managing spine trauma. It is challenging to provide high quality spine care across a region as spine fractures are common, the majority are stable, and spine trauma specialists are relatively uncommon and tend to be concentrated in trauma centers. This creates a high volume of work, much of it dedicated to finding the small proportion of patients with unstable fractures, while treating all fracture patients as if they have an unstable spine until instability can be ruled out by an expert. In the United States, with its decentralized health care system, inter-hospital policies about spine trauma are uncommon. Spine fractures are managed by a variety of specialties including emergency medicine, internal medicine, physiatry, orthopaedic surgery, and neurosurgery, depending on local culture and expertise of the managing physician. In countries with centralized, government-run health systems, protocols can be developed to triage and manage spine trauma patients in a more consistent pattern across the system. In order to evaluate the efficiency of the United Kingdom (UK) system, Hill and Marynissen analyzed 100 consecutive spine trauma patients managed by general orthopaedists at their district general hospital using an electronic consultation with spine specialists at the regional trauma hospital. The high-energy trauma and spinal cord injuries were directly transferred to the trauma center and were not included in this analysis. In the current cohort, the average age was 86 years, and 85% were female, suggesting that the vast majority of fractures represented low energy fragility fractures. Only 6% of patients had an unstable injury, and 17% were found to have no fracture after work-up. Eighty percent of patients underwent a CT scan, and 37% underwent MRI as recommended by the spine trauma specialist. The average response time from consultation until the spine specialist made initial recommendations was 19 hours, and the median time to complete imaging and develop a definitive management plan was 72 hours. British orthopaedic guidelines recommend that spinal immobilization should be maintained for no more than 48 hours, and the authors found that only 34% of patients had imaging completed and a definitive plan within that timeframe.

The authors have produced an interesting study looking at a health delivery topic that affects patients and providers on a daily basis. Similar issues arise in the United States, though there tend not to be spine-specific protocols for inter-hospital consultation. In general, patients will frequently present to smaller hospital emergency departments where low energy spine fractures are diagnosed. If the local physicians are trained in treating these stable fractures, sometimes no consultation to the trauma center is generated. Other times, it results in a phone call and triage of the patient by the trauma center. Now that images can be transmitted electronically, the spine specialists can usually evaluate the images and make recommendations. In the past, this was not possible, and management was based on radiology reports, which varied in their accuracy. Unlike the British system, in which the spine consultation can be delayed depending on the availability of the spine specialist, in the United States there is an expectation that this consultation be performed whenever the phone call is placed. As a result, many of the consultations are performed by on-call residents. In some cases, this can result in inappropriate management, either missing an unstable fracture or transferring a patient to a higher level of care unnecessarily. I am unaware of a paper looking at this topic in the United States, but it seems likely that the time to imaging or definitive management is faster in the US system. One of the barriers to speedy care in the British system is the lack of 24-hour access to MRI. While many small US hospitals lack MRI access, this situation frequently results in the transfer of patients to tertiary care centers when a consultant recommends that study. This paper does a nice job shining a light on factors that delay care and are likely present in most health systems. Hopefully more work can be done on this topic to expedite care and prevent the negative side effects of unnecessary, prolonged bedrest on the vulnerable elderly population.

Please read this article in the October 15 issue. Does this change how you consider the regional management of spine trauma patients? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS

Associate Web Editor

 

Friday, October 5, 2018

When do we let patients drive after cervical spine surgery?

Patients frequently ask when they can return to driving after cervical spine surgery, and surgeons have to make recommendations without much evidence supporting their advice. There are a handful of studies looking at this, and most make recommendations based on driver reaction time, a metric that evaluates a specific, focused factor that probably does not capture overall driving ability.1 Given the lack of evidence on this topic, Dr. Moses and colleagues performed a survey of Cervical Spine Research Society (CSRS) meeting attendees to determine practice patterns and see if a consensus exists on the topic. In addition to evaluating return to driving, they also evaluated recommendations for post-operative cervical collar use, which would likely impact decisions about return to driving. They had 71/98 surveys they handed out completed, and 80% of respondents were orthopaedic spine surgeons (20% neurosurgeons). In general, most surgeons allowed patients to return to driving between 2 and 6 weeks, with 2 weeks being the most common response (40%) following 1 or 2 level ACDF or disk replacement. Six weeks was the most common response for > 2 level ACDF (52%) or laminectomy and fusion (60%). About 40% of surgeons recommended less than 2 weeks of driving restriction following foraminotomy or disk replacement. In terms of collar use, there was also a broad range of practices. Following single-level ACDF, 42% used no collar, 27% used a hard collar, and 31% used a soft collar. Of those who used a collar, 40% used it for 2 weeks and 36% for 6 weeks. For > 2 level ACDF, 23% used no collar, 68% used a hard collar, and 10% used a soft collar. The majority (57%) kept the collar in place for 6 weeks. Similar bracing patterns were reported for laminectomy and fusion. Following foraminotomy and disk replacement, approximately 2/3 of surgeons used no collar, and under 10% used a hard collar. Surgeons with over 15 years of practice experience were more likely to allow patients to return to driving in under 2 weeks following > 2 level ACDF and laminectomy and fusion (47% vs. 24%).

The authors have done a nice job administering a survey on a topic on which there is very little literature to guide practice. In these situations, consensus is likely the best way to determine best practice patterns. Not surprisingly, given the lack of evidence on this topic, there was no clear consensus and a wide variation in practice. When deciding about return to driving, one must consider reaction time, range of motion, pain severity, and judgment. All of these impact driving ability, and cervical spine surgery, collar use, and opioid medication can adversely affect these factors. There is one RCT that demonstrated no advantage to collar use following one level ACDF, but no data looking at other procedures.2 The authors point out that driving while wearing a cervical collar or while taking narcotic pain medication likely put the patient and the surgeon who approved return to driving in legal jeopardy. Both factors almost certainly have a negative effect on driving performance. The most concerning finding in the paper is that 28% of surgeons allow patients to drive while taking opioids, and 31% allow driving in a cervical collar. It seems as though these practices should be changed in order to promote driver safety and reduce legal exposure. This survey has the same limitations of all survey studies, the most important of which is potential limited generalizability to the entire population of spine surgeons. However, the authors reported a 70% response rate, which is relatively good, and this group of surgeons at CSRS likely have practices that mirror those of the greater spine surgeon community. The most important finding of this study is the wide variation in practice, as would be expected given the lack of evidence on the topic. It would be helpful if professional societies could issue guidelines on collar use and return to driving as these issues come up after every surgery, and it would be nice to inform patients that our recommendations are based on something (slightly) more solid that our individual opinions. Such guidelines could also provide some legal cover, provided they are followed.

Please read Dr. Moses's article on this topic in the October 15 issue. Does this change how you view collar use and return to driving following cervical spine surgery? Let us know by leaving a comment on The Spine Blog.

Adam Pearson, MD, MS

Associate Web Editor

 

REFERENCES

1.            Alhammoud A, Alkhalili K, Hannallah J, Ibeche B, Bajammal S, Baco AM. Driving Safety after Spinal Surgery: A Systematic Review. Asian Spine J 2017;11:319-27.

2.            Campbell MJ, Carreon LY, Traynelis V, Anderson PA. Use of cervical collar after single-level anterior cervical fusion with plate: is it necessary? Spine (Phila Pa 1976) 2009;34:43-8.


Sunday, September 30, 2018

The effectiveness of PT for acute LBP in a military population

​Physical therapy (PT) has been a mainstay in the treatment of acute low back pain (LBP), along with admonitions to avoid bedrest, anti-inflammatory medication, and education about the benign natural history of the condition. Level 1 data on these interventions are sparse, and, given the high incidence of acute LBP, evidence should exist to guide treatment as the potential societal cost of these interventions is relatively high. In order to address this, Dr. Rhon and colleagues performed an RCT comparing usual care to early physical therapy for the treatment of acute LBP in an active military population. They enrolled 119 patients who all attended a 20 minute educational class about acute LBP and were then randomized to receive usual care (UC) or 8 PT sessions over the next 3 weeks. The primary outcome measure was the Oswestry Disability Index (ODI) score at one year, and they also recorded numeric pain rating scales and healthcare related costs. The average age was 27, and 85% of patients were male. The only patient reported outcome that was significantly different was the 4 week ODI score, which was 4 points better in the PT group. The PT group spent about $1,000 more on LBP related treatments, though overall one-year healthcare costs were similar for the two groups. The UC group spent about $700 more on non-LBP related care.

The authors have done a nice job performing an RCT to study the effect of early PT on acute LBP outcomes. Their results suggest that early PT does not yield any long-term advantage compared to UC in active military patients with acute LBP, and the short-term advantage is likely clinically insignificant. An important consideration when interpreting these data is the population to which they apply:  active military patients with acute LBP. Randomized trials offer the benefit of eliminating sources of bias and confounding, however, they tend to answer very narrow questions in very specific populations. These results are not generalizable to the non-military population, to patients with chronic LBP, or to those with radiculopathy or claudication. The other major limitation of this study is that it was likely underpowered according to the authors’ power analysis, however, there were no trends indicating that PT likely resulted in a clinically significant long-term benefit compared to UC. The most important finding from this trial is the benign natural history of acute LBP in a young, fit military population. These patients should be reassured that they will most likely get better regardless of treatment received, and expensive or time-consuming early treatment is probably not necessary. For the minority whose symptoms persist, more intensive treatment can be started.

Please read Dr. Rhon’s article on this topic in the October 1 issue. Does this change your view of the role of PT in acute LBP? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS

Associate Web Editor

Friday, September 21, 2018

ALIF for DDD?

The best treatment for axial low back pain (LBP) in patients with degenerative disk disease (DDD) remains unknown, with relatively modest improvements reported after both surgical and non-operative treatment. Most of the RCTs on the topic have demonstrated no differences in outcomes between fusion and non-operative care,1-3 though a more recent Japanese RCT demonstrated superior outcomes for the fusion group.4 This study by Ohtori et al. also compared outcomes between ALIF and posterolateral fusion (PLF) and showed superior outcomes for the ALIF patients on some outcome measures. The groups were small (15 ALIFs, 6 PLFs), so strong conclusions regarding the advantage of one technique over the other could not be drawn. In order to evaluate their outcomes with ALIF for DDD, Dr. Kleimeyer and colleagues from Stanford and MGH retrospectively compared patient reported outcomes between 42 patients who underwent ALIF and 33 who were treated non-operatively for one or two level DDD. At a mean follow-up of 7.4 years, they found that the ALIF patients improved significantly more on a visual analog scale for back pain (3.4 vs. 0.9) and on the ODI (14 points vs. -0.2 points) compared to the non-operative patients. At baseline, the two groups were similar, with the surgery group trending towards having more smokers and patients involved in active litigation. Baseline ODI scores indicated relatively mild disability (27.4 in the ALIF group and 23.9 in the non-operative group), and patients had a mean age of about 50. Complications were low in the ALIF group, with about a 10% pseudarthrosis rate (1 reoperation for pseudarthrosis) and 12% rate of radiographic, asymptomatic adjacent segment degeneration. The authors concluded that ALIF was more effective for axial back pain associated with one or two level DDD than non-operative treatment.

While RCTs performed in Europe in the early 2000s painted a grim picture for the effectiveness of fusion for DDD, the RCT by Ohtori and the current study suggest more favorable outcomes. The major limitation of the current study is that it is a non-randomized, retrospective cohort study prone to bias. The two groups appeared similar on measured baseline characteristics, but factors such as educational attainment, socioeconomic status, body mass index, and psychological and medical comorbidities were not measured. These have all shown to be strong predictors of outcomes following lumbar surgery and may have been different between the two groups. The two groups were also inherently different in that one group chose to have surgery, while the other group chose not to. The patients also had relatively low levels of baseline disability with ODI scores in the 20s, and the majority were working preoperatively. In comparison, the patients in the Fairbank, Bros, and Fritzell RCTs had baseline ODI scores in the 40s, and the majority were out of work. In the Ohtori, the baseline ODI scores were in the 60s. The European studies demonstrated 12-14 point improvements on the ODI with surgery, similar to the current study. These older studies also showed similar, if slightly less, improvement with non-operative care compared to the surgical groups, while the current study showed effectively no improvement with non-operative care. The European RCTs all employed PLF, and it is possible that ALIF has better outcomes for this problem. Given that the current study represents Level III data, one cannot use it to conclude that ALIF is superior to non-operative treatment for axial LBP associated with DDD. However, this and the Ohtori study should provide motivation to perform an RCT comparing ALIF to structured non-operative care for these patients, preferably in a US or international population.

Please read Dr. Kleimeyer’s article on this topic in the October 1 issue. Does this change how you view the role of ALIF for the treatment of DDD? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS

Associate Web Editor

REFERENCES

1.            Brox JI, Sorensen R, Friis A, et al. Randomized clinical trial of lumbar instrumented fusion and cognitive intervention and exercises in patients with chronic low back pain and disc degeneration. Spine (Phila Pa 1976) 2003;28:1913-21.

2.            Fairbank J, Frost H, Wilson-MacDonald J, Yu LM, Barker K, Collins R. Randomised controlled trial to compare surgical stabilisation of the lumbar spine with an intensive rehabilitation programme for patients with chronic low back pain: the MRC spine stabilisation trial. BMJ 2005;330:1233.

3.            Fritzell P, Hagg O, Wessberg P, Nordwall A. 2001 Volvo Award Winner in Clinical Studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine (Phila Pa 1976) 2001;26:2521-32; discussion 32-4.

4.            Ohtori S, Koshi T, Yamashita M, et al. Surgical versus nonsurgical treatment of selected patients with discogenic low back pain: a small-sized randomized trial. Spine 2011;36:347-54.