By Prof. Dr. H. Michael Mayer - ms T · Content The pathology of spinal stenosis 4 The treatment of spinal stenosis 6 Spinal stenosis treatment options and outcomes 8 Conservative

Treatment pathways in lumbar spinal stenosisBy Prof. Dr. H. Michael Mayer

Content

The pathology of spinal stenosis 4

The treatment of spinal stenosis 6

Spinal stenosis treatment options and outcomes 8 Conservative treatment 9

Surgical procedures 10

Indirect decompression 10

Direct (open), microsurgical decompression 12

Lumbar spinal stenosis with associated dominant back pain 14

Lumbar spinal stenosis with dominant back pain – surgical treatment options and outcome 16

Direct decompression 17

Direct decompression + spinal fusion 18

Direct decompression + dynamic stabilization using ligament devices or pedicle screws 20

Direct decompression + dynamic stabilization using interspinous/ interlaminar spacers 21

The coflex® study - design and execution 22

Continuum of care for lumbar spinal stenosis with and without back pain 24

References 26

Treatment pathways in lumbar spinal stenosis 3

Degenerative lumbar spinal stenosis has become one of the most frequent pathologies treated by spine surgeons around the world. Since the 50’s of the last century, decompression techniques have been developed and refined. Total laminectomies with destruction of the posterior tension band system and the risk of iatrogenic destabilization of the motion segment have become rare. Modern, minimally invasive decompression techniques can avoid such destabilization in the majority of the cases. However, cases where degenerative lumbar spinal stenosis is associated with deformities, e.g. degenerative lumbar (‚de novo’) scoliosis or translational instabilities like degenerative spondylolisthesis, still bear some uncertainty in decision making. Is it enough to decompress the spinal canal, or is it necesssary to add some kind of correction and/or stabilization? This is true for patients which are symptomatic (back pain) as well as for those whose deformity/instability is asymptomatic.

International standards which tell us ‚when to do what’ are still missing. The following brochure should help surgeons in decision making. Although I realize that this personal guideline based on longterm experience and intensive literature review not completely fulfills the requirements of an evidence-based medical guideline, it does though represent what we can learn from the current scientific literature and what my own experience with the treatment of degenerative lumbar spinal stenosis in the last 20 years has taught me.I sincerely hope that it will be helpful and will contribute to a more sophisticated view on a seemingly simple clinical problem.

Yours

Michael Mayer

Prof. Dr. med. habil. H. Michael MayerHead of Spine CenterSchön Klinik München Harlaching

Editorial

Dear readers,

4 Treatment pathways in lumbar spinal stenosis4

The pathology of spinal stenosis

Pathological changes

Lumbar spinal stenosis is one of the most common spinal conditions seen in adults. The fact that most of the pathological changes associated with the condition occur as a result of degenerative changes or a combination of congenital and degenerative changes means that age-related progressive degeneration of the intervertebral disc represents a key factor. It is likely that this progressive degeneration is based on genetic predisposition, and that it is modulated by external factors (e.g. excess weight, lack of exercise, incorrect posture or lifting techniques). A decrease in disc height leads to an anular bulge (clinical variant: spinal disc herniation) (Figure 1) and increased pressure on the joints, particularly during spinal extension. In many cases, this leads to what is referred to as spondylosis deformans, a condition that is associated with hypertrophic changes which result in thickening of both the joint surface and the joint capsule (Figure 2).

In addition to this, there is hypertrophy or thickening of the ligamentum flavum, a development that even in the absence of any additional changes may occasionally lead to spinal stenosis (Figure 3).

Figure 1: MRI: Multi-level degenerative disc disease L1-2-3-4-5

Figure 2: CT scan axial view: Spondylosis with thickening of the articular processes and spinal stenosis

Figure 3: Spinal stenosis secondary to ligamentum flavum hypertrophy

The exact etiology of this ligamentum flavum hypertrophy remains to be established. The main consequence of spinal disc degeneration, i.e. rotational instability resulting in increased pressure on the posterior complex, appears to be a causal factor. (1, 2)

In terms of future therapeutic decisions, the morphological and clinical changes arising as a result of associated pathologies such as degenerative spondylolisthesis (Figure 4) and degenerative (de novo) lumbar scoliosis (Figure 5), play an important role in more than 50% of cases.

Degenerative spondylolisthesis is usually associated with central stenosis and represents an aggravating factor in clinical presentation. When lumbar scoliosis is present, the clinical and morphological features of the condition are more likely to include lateral (lateral recess) and/or foraminal stenosis. When the above-named conditions are characterized by flexibility or instability, the severity of the symptoms associated with them is usually dependent upon postural position and movement.


The pathology of spinal stenosis

Clinical presentation

More than 85% of patients with degenerative spinal stenosis have a history of back pain or report back pain to be a more or less prominent feature of their symptoms. (3) The cardinal symptom of lumbar spinalstenosis, however, is spinal claudication, a condition that is associated with a reduction in both walking distance and standing time, a tendency for the leg muscles to tire quickly when walking, heavy legs, muscle pain reminiscent of muscle ache which is associated with intermittent radiating pain, as well as hypoesthesia and dysesthesia. Only rarely do motor deficits formpart of early symptoms. Less than 5% of patients are found to have a history of symptoms indicative of undiagnosed cauda equina syndrome, which characteristically includes difficulties emptying the bladder and occasional genital sensory disturbance. Symptoms are almost always reversible as well as dynamic, with standing or increased lordosis of the spine leading to a worsening of symptoms, and sitting and bending forward leading to an alleviation of symptoms. Lumbar lordosis is usually absent during standing or walking.

‚Natural‘ progression

The normal course of untreated or conservatively treated lumbar spinal stenosis has been studied extensively (please also refer to Chapter 3). The majority of patients (> 65 – 85%) find that symptoms remain either unchanged or worsen over a period of between 2 and > 4 years after the initial onset of symptoms. (4,5)

Figure 4: Degenerative spondylolisthesis II°

Figure 5: Degenerative lumbar scoliosis


The treatment of spinal stenosis


The treatment of spinal stenosis

The past few decades have seen significant improvements in the types of clinical investigations and diagnostic equipment available for the diagnosis of lumbar spinal stenosis. This has led to a significantly more detailed understanding of the clinical picture, and has prompted the development of new therapeutic approaches.Five of these developments have been of particular significance and have changed our attitudes, particularly with regard to surgical (curative) procedures.

Imaging Magnetic resonance imaging, including open upright and functional MRIs, functional x-ray imaging, and CT scans can be used to provide precise information on the morphology (changes in the bones, ligaments, discs etc.), location (central, recess, foraminal) and extent (level) of the stenosis present, as well as any potentially aggravating functional changes (deformity, instability) that may be present. This is essential for an in-depth approach to treatment planning.

Semi-invasive diagnostic techniques

Exact pin-pointing of the origin of the pain experienced is particularly important in patients with pain symptoms associated with stenosis (radicular pain, back pain etc.). The use of image intensifier-guided or

symptoms, and by employing minimally-invasive and safe treatment methods.Age, duration of symptoms, comorbidities, the levels of risk associated with surgery and anesthesia, as well as goals and expectations form the basis of all individualized treatment decisions.

Surgical techniques New developments and improvements in the surgical techniques available are responsible for changing the face of lumbar spinal stenosis treatment. Nowadays, decompression of neural structures (direct or indirect) is carried out using only minimally-invasive procedures that are capable of addressing the cardinal symptoms of spinal stenosis. The treatment of associated back pain or functional components usually involves additional corrective and/or stabilizing measures (dynamic or rigid).

CT-guided diagnostic injections can help to identify the origin of radicular pain or back pain, as well as helping to identify the exact nature of the latter (joint, disc, functional etc.).

Anesthesiology and intensive care medicine

The initial onset of symptoms in patients with degenerative spinal stenosis is usually in the 7th or 8th decade of life, with > 80% of patients also reporting concomitant diseases. (6) Advances made in these medical specialties are resulting in an increase in the safety of surgical interventions in elderly patients and patients with multiple comorbidities.

Patient expectations

The increase in life expectancy seen in Western industrialized nations is responsible for an increasing number of elderly people displaying a high degree of mental and physical fitness, with many managing to enjoy a physically active lifestyle well into their 80s. As a result of this development, patient expectations are not merely focused on maintaining the status quo but are focused on achieving ‚restitutio ad integrum’ i.e. a restoration to the original condition, including a return to physical exercise. This aim can only be achieved by employing a treatment strategy that is informed by the specifics of the individual case, by taking into consideration individual risk factors as well as clinical and morphological


Spinal stenosis treatment options and outcomes

9Treatment pathways in lumbar spinal stenosis


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In summary, it appears that there is insufficient evidence for the effectiveness of conservative treatment in symptomatic lumbar spinal stenosis and that published data suggest positive and lasting effects only in relation to surgical treatment.

Conservative treatment

The conservative treatment of lumbar spinal stenosis attracts controversy for a number of reasons.Firstly, it is unlikely that a reversal of the morphological changes responsible for a narrowing of the spinal canal occurs during the natural course. Secondly, many of the patients on long-term conservative treatment who require surgical interventions at a later stage, find themselves at a distinct disadvantage because neurological symptoms have already become manifest (at rest). Late-stage surgical interventions do not usually result in the complete reversal of such symptoms. (7) Another important factor is the prevention of a gradual increase in the degree of immobilization, and the risk of secondary complications arising from it.

Conservative treatment options should only be considered if they are unlikely to have an adverse effect on the patient‘s chances of successful surgical treatment at a later stage or if the level of risk associated with surgery is unacceptably high. A number of prospective studies have investigated conservative treatment options. A prospective study involving 80 patients (in-hospital conservative treatment for a duration of 2 weeks and consisting of traction, lumbosacral corset and repeated epidural injections) reported that only 34.8% of patients showed significant improvements (JOA Score) over a follow-up period of 2 years. (5)

A recent meta-analysis, which analyzed the results of 21 studies, investigated the effects of different conservative treatments (8) and found that, when compared to placebo and a variety of different medical treatments such ascalcitonin, paracetamol and epidural injections had no significant effect on the symptoms experienced by patients with spinal stenosis. Prostaglandins and gabapentin had no effect on walking distance. Physical therapy had no major effect on functional levels or quality of life. (8) The studies that were included in the analysis all represented a category IV or V level of evidence.

As early as 2000, Amundsen et al. published data from a prospective, randomized study, which provided evidence of superior outcomes following surgical treatment vs. conservative treatment. (9) The study, involving a total of 100 patients with lumbar spinal stenosis receiving either surgical or conservative treatment, showed that after an average 4 years of follow-up, only 50% of the conservatively treated patients (vs. 80% of surgical patients)were satisfied with the outcome of treatment. (9) Pearson et al. (2012) confirmed this with a prospective study involving 654 patients, which also reported significantly better outcomes following surgical treatment. (6)

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Hierarchy of EBM (Evidence Based Medicine)simplified from CEBM Oxford 2001

Level Type of evidence

I

Systematic reviews of well controlled Randomized Controlled Trials (meta-analysis) or single RCT with narrow CI (confidence interval)

IISystematic review cohort studies or lesser quality RCTs

IIICase controlled studies (non randomized)

IV Case series (no control group)

(V)Expert opinion (GOBSAT – Good Old Boys Sat Around Table)


Surgical procedures

Figure 7: Percutaneous implantation

The main goal of surgical treatment is the effective decompression of the central and/or lateral canal and/or of the intervertebral foramen. This can be achieved with different surgical procedures with an increasing degree of invasiveness.

Indirect decompression

The introduction of interspinous spacers has expanded the spectrum of treatment options available in lumbar spinal stenosis. The principle behind these devices is based on the biomechanical effects of the spacer, which distracts the spinous processes, thus indirectly widening the spinal canal and the intervertebral foramen. (10, 11)

In clinical terms, the effect of this process is akin to flexion (forward bending) or decreasing the lordosis of the lumbar spine, which in many cases will alleviate symptoms, particularly in the early stage of spinal stenosis. Typical examples of this category of implants are the X-StopTM (Medtronic) and the In-Space (DepuySynthes).

The two systems are based on the same principle: distraction of the spinous processes increases the space between them, thus indirectly widening the central spinal canal and the intervertebral foramen (Figure 6).

However, they differ in terms of the degree of invasiveness involved. While the In-Space-type device is inserted via a percutaneous lateral approach, using a small skin incision (Figure 7), the X-StopTM is inserted via a midline approach, and requires incision of the lumbar fascia and stripping of the paraspinal muscles.

Figure 6: The principle behind interspinous distraction and widening of the spinal canal



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Procedures involving indirect decompression when used as stand-alone treatments are indicated in the early, dynamic stages of lumbar spinal stenosis. In rare cases, they may also be indicated in high-risk patients if the risks associated with an invasive procedure are judged to be considerable. Data currently available on these procedures mainly belong to the level of evidence categories IV-V (with the exception of X-StopTM; however, evidence is limited to proven benefit compared to conservative treatment). What makes these procedures attractive is the low degree of invasiveness involved, particularly during percutaneous implantation. What needs to be considered, however, is that these procedures involve temporary, non-stabilizing implants, and that their effect is likely to be limited to delaying the need for additional treatment.

Indications and results

Procedures involving indirect decompression are only indicated in those cases where clinical symptoms and radiological evidence suggest the presence of dynamic spinal stenosis, i.e. symptoms should improve with forward bending and the affected segment(s) should retain physiological mobility during flexion/extension. There must be no deformities or macro-instability. This means that the use of interspinous spacers as a 'stand-alone' treatment is usually limited to the early variants of spinal stenosis.

The first data ever to be published in relation to this procedure involved the X-StopTM device. A prospective, randomized study was able to show that when compared to conservative treatment, the implantation of X-StopTM resulted in greater benefits for patients with spinal stenosis and spinal claudication. (12, 13, 14) Initial data describing the same effect in patients with spinal stenosis and grade 1 degenerative spondylolisthesis could

not be replicated in later studies. (15, 16)

Although X-StopTM interspinous spacers are described as minimally invasive, their implantation involves open surgery, and usually requires larger surgical incisions than direct decompression using modern microsurgical techniques (Figures 8/9). (17, 18) Above all, this calls into question the clinical benefits ascribed to this method.

Percutaneous implantation is far less invasive in nature. The first-ever implantation of an In-Space-type spacer was performed in 2006. Initial results, based on 41 patients, showed a significant improvement in the Oswestry Disability Index and significant pain relief in patients with dynamic degenerative lumbar spinal stenosis. (19, 20)

When compared to all other interspinous spacers currently available, In-Space appears to be the most minimally-invasive type (Figure 8). For instance, intraoperative blood loss was reported as < 5 ml, operating room time as usually less than 15 minutes per segment, and no relevant intraoperative or perioperative complications were observed*.

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Figure 8: Wound after minimally-invasive implantation of In-Space.

*Own, unpublished data.


Direct (open), microsurgical decompression

Direct decompression of the spinal canal represents the most effective surgical treatment for spinal stenosis.In nearly all cases of spinal stenosis, microsurgical techniques can achieve satisfactory results without spinal stability being compromised. (17, 18) In the majority of cases, laminectomies and hemilaminectomies are no longer indicated. The same applies to surgery involving multilevel spinal stenosis. (21)

Surgical principle: once interlaminar access has been established, the first step is to expose and decompress the cauda equina and lateral recess (Figure 9).

Once this step has been completed, the operating table and microscope are tilted to the opposite side. In what is sometimes referred to as a unilateral ‚cross-over‘ approach, decompression of the spinal canal and lateral recess is then performed on the contralateral side as well (Figure 10).

The major advantage of this particular procedure is that removal of approximately 30% of the caudal articular process is only required on the side that is used for access. The muscles, outer joint capsule and inferior articular process on the contralateral side remain virtually untouched. This allows decompression whilst maintaining spinal stability (Figure 11).

Figure 11: MRI before (left) and after (right) successful bilateral decompression via an unilateral approach. Both joints remain virtually completely intact. Soft tissue damage along the route used for procedural access is minimal.

Figure 9: Ipsilateral, microsurgical

decompression (21)

Figure 10: Contralateral ‚cross-over‘

decompression (21)



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open surgery procedures involving direct (microsurgical) decompression are considered the most effective types of procedures that provide good, reproducible results in spite of the fact that there is currently no difference in the level of evidence available in support of these procedures and those involving indirect decompression (this, by the way, also applies for older ‚standard procedures‘ such as hemilaminectomies and laminectomies!). However, clinical results are good and reoperation rates are low (Table 1 and 2).These procedures are not limited to specific types of spinal stenosis. There are, however, limitations with regard to their use in patients with associated symptoms (back pain), and patients with obvious instability.

Indications and results

This procedure is suitable for all types of lumbar spinal stenosis. Scar tissue formation in patients who have previously undergone surgery may render the unilateral approach more difficult or even impossible. In such cases, a bilateral approach may be required. There are no contraindications. Using a ‚slalom technique‘, the same procedure may be used for multilevel stenosis. (21) This technique is also recommended as standard in cases with adjuvant implantation of dynamic stabilizers due to the fact that it helps

to preserve the anatomical structures required to maintain stability. In the neurosurgical literature, this procedure is considered standard. The aim of treatment is always to achieve the decompression of neural structures. This is why the best results are achieved in patients with predominant ‚leg symptoms‘ (please also refer to ‚Lumbar spinal stenosis with associated back pain‘) although, as a ‚side effect‘ of this kind of treatment, more than 65% of the patients also experience a relief of their back pain. (7)

Table 1 and Table 2 provide summaries of published data and reoperation rates.

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authorfollow-up

(y)success rate

Sasai K et al J Neurosurg Spine 9;554-559, 2008 (22) 4 88%

Costa F et al, J Neurosurg Spine 7;579-586, 2007 (23) 5 87.9%

Yagi M et al, J Neurosurg Spine 10;293-299, 2009 (24) 1.5 90%

Papavero L et al; Neurosurgery 65;182-187, 2009 (25) 1 83.9%

Müslüman AM et al, J Neurosurg Spine online Aug 2011 (26) 2 80%

Toyoda H et al, Spine 36: 410-415, 2011 (27) 5 73.5%

Table 1: Success rates after microsurgical “cross-over” decompression

author n follow-up (y) Reoperation rate

Toyoda H et al Spine 36: 410-415, 2011 (27) 57 5 7%

Papavero L et al; Neurosurgery 65;182-187, 2009 (25) 165 1 4.2%

Costa F et al, J Neurosurg Spine 7:579-586, 2007 (23) 374 5 0.8%

Kelleher MO et al, Spine 35:E981-987, 2010 (28) 75 5 10%

Matsumara A et al, J Neurosurg Spine 13:758-765, 2010 (29) 50 2 0.5%

Müslüman AM et al, J Neurosurg Spine August 2011 (26) 84 3 1.2%

Table 2: Reoperation rates following microsurgical “cross-over” decompression


Lumbar spinal stenosis with associated dominant back pain


Lumbar spinal stenosis with associated dominant back pain

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Current international consensus exists in relation to changes affecting the curvature and stability of the spine, with experts agreeing that these require decompression surgery with additional stabilization. However, there is ongoing controversy regarding the issue whether decompression procedures that do not compromise spinal stability should also be accompanied by spinal stabilization in patients presenting with significant back pain.

Nearly all patients with lumbar spinal stenosis present themselves with back pain. In an FDA regulated IDE study comparing fusion surgery with dynamic stabilization in spinal stenosis patients, 98.6% of all patients reported back pain of > 6 months‘ duration. Of these, 87.4% reported having had this pain for more than one year. (30)

In the majority of cases, back pain is an associated symptom. However, if its severity is such that it exceeds that of spinal-stenosis-related leg symptoms (spinal claudication, sciatica), it must form part of the treatment-planning process, with particular emphasis being placed on the etiological factors involved. The morphological changes involved are usually arthritic changes affecting the facet joints (arthrogenic back pain) (Figure 12) and/or disc degeneration (discogenic back pain) (Figure 13).

Figure 12: Spondylosis deformans with spinal stenosis (CT myelogram)

Figure 13: "Erosive" osteochondrosis L4–5 (type I Modic changes). MRI T1-weighted sequence after administration of contrast agent, showing typical edema formation affecting the cancellous bone near the end plates in L4 and L5

In more than 50% of all cases, it is morphological and/or functional changes affecting the curvature of the spine, that contribute to back pain and to an aggravation of spinal stenosis. Changes typically seen include degenerative spondylolisthesis (Figure 14) and degenerative lumbar scoliosis (Figure 15), both of which may differ in their clinical presentation.

Figure 15: (left) monosegmental shift (stable) L3–4 and (right) unstable degenerative lumbar scoliosis (de novo)

Figure 14: (left) Stable and (right) unstable degenerative spondylolisthesis L4–5


Spinal stenosis with dominant back pain – surgical treatment options and outcome


Direct decompression

A number of studies have investigated how back pain associated with lumbar spinal stenosis may be alleviated by decompression surgery alone. Results from our own investigations have revealed significant improvements in back pain in patients with spinal stenosis without abnormalities in the curvature of the spine or spinal instability. (31)

In 2012, Pearson et al. published the results of the SPORT (Spine Patient Outcomes Research Trial) study. Results from their prospective, randomized study involving 654 patients with lumbar spinal stenosis showed that, after a mean follow-up period of 4 years, the treatment effect of decompression surgery in patients with predominant back pain was significantly lower (p < 0.05) than that observed in patients without back pain. (6)

As early as 2009, Kleinstück et al. reported similar findings as part of their retrospective analysis of data from 221 of their own patients,

obtained via the Spine Tango database. Their analysis revealed worse outcomes in terms of COMI scores (<0.001) and showed that these outcomes were positively correlated with levels of back pain reported prior to surgery. (32)

Other researchers have reported similar results, particularly in relation to patients with concomitant abnormalities in the curvature of the spine or spinal deformities. Reporting on clinical symptoms in patients with spinal stenosis and significant back pain with concomitant spinal deformities (degenerative spondylolisthesis or degenerative lumbar scoliosis), Toyoda et al. were able to show that, after a follow-up period of 4 years, improvements in clinical symptoms were limited to 64.1% of patients with degenerative spondylolisthesis and 51.6% of patients with degenerative lumbar scoliosis. (27)

Kelleher et al. found that 5-year reoperation rates were significantly higher in patients presenting with both spinal stenosis and degenerative lumbar scoliosis. (28)

Take HoMe Message

Most of the studies investigating the effects of decompression surgery alone belong to the level of evidence categories I – Iv. In spite of this, it should be assumed that decompression alone is likely to produce worse outcomes in patients presenting with significant back pain and/or spinal deformities than in patients with no back pain or back pain that is not clinically relevant.


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Direct decompression + spinal fusion

The combined use of surgical decompression and different types of fusion is generally regarded as the ‚gold standard‘ in the treatment of patients with spinal stenosis andsignificant back pain. According to current scientific opinion, the clinical outcomes associated with different fusion procedures can be regarded as acceptable. (33–38) Overall success rates range between approximately 70–80%, with success rates slightly higher in patients with degenerative spondylolisthesis. (39, 40) In spite of this, the lack of evidence-based data means that the scientific community remains skeptical with regard to fusion surgery as a treatment for degenerative changes affecting the lower spine. (41)

In addition, patients with lumbar spinal stenosis usually represent a group of high-risk surgical patients. The average age of patients is over 70 years of age, with 40-80% of them presenting with significant comorbidities, including diabetes, high blood pressure and other cardiovascular problems. Patients also usually present with spinal rigidity and poor bone quality. Considering the fact that both complication and mortality rates are higher in this patient group, these factors certainly have an impact on surgical outcomes.

Complications associated with spinal surgery in elderly patients

The overall risk of suffering spinal surgery-related complications increases with the age of the patient. The risk of suffering serious complications is 9 times higher in patients aged over 69 years (42) as compared to patients under 40 years, with an overall rate of serious complications in patients over 80 years reported as > 35% . (43) In 2003, a study investigating complication rates for decompression and spinal fusion in patients aged > 70 years found that the overall rate of complications in the patient group investigated was 80%. (44) As early as 1993, Medicare data showed that the combination of decompression surgery and fusion surgery increases the risk of complications by a factor of 1.9, the rate of blood transfusions by a factor of 5.8, 6-week mortality by a factor of 2.0, and the risk of requiring permanent nursing care by a factor of 2.2. (45)

Using data obtained from the Spine Tango database, Sobottke et al. revealed the age of the patient to be the single most important independent risk factor. (46)

The current scientific literature reports complication rates for decompression + fusion between 12–100%. (33, 34, 35, 37, 47)

Mortality associated with lumbar fusion surgery

Recent epidemiological research involving data on more than 1.2 million spinal procedures reported an average mortality rate of 0.2% (48), with the age of the patient once again being identified as a highly significant independent risk factor (p > 0.0001).

Mortality rates following fusion surgery have been reported as being four times higher than those observed following surgery without spinal fusion (49), while the use of implants has been associated with a three-fold increase in mortality rates when compared with procedures that did not involve the use of implants. (49)

Other studies investigating overall surgery-related mortality in patients with lumbar spinal stenosis have reported rates of between 1–15%. (33, 45)

Reoperation rates after direct decompression + fusion

With regard to the issue of reoperation following lumbar fusion surgery in patients with degenerative disease, there is a general tendency among clinical practitioners to underestimate both the rate at which these surgical procedures occur as well as the outcomes associated with them. Reoperation rates in the first 3–5 years following fusion surgery range between 11.9–18.2% (50, 51, 52), with increasing rates of 21.5–25.4% 15 years after surgery. (53, 54, 55) Pseudarthrosis, hardware failure and adjacent segment disease represents one of the most common reasons for reoperations, particularly in elderly patients. Postoperative sagittal balance and rigidity of fixation are further key factors that can influence the level of stress on the adjacent segments. (56) The annual incidence of further surgery involving adjacent segments is approximately 2.5% following transforaminal and posterior lumbar interbody fusion (TLIF/PLIF), both of which are very common procedures. (57) Depending on the life expectancy of the patient, this factor must be taken into


Take HoMe Message

A critical review of these data shows that the results of fusion surgery are at best acceptable, that there is only low level evidence available in support of spinal fusion procedures and that these are associated with significant risks, particularly in elderly patients. Given that fusion surgery is associated with significantly increased mortality rates, perioperative and postoperative complication rates of up to 70%, reoperation rates of up to 30% in the first 15 years following surgery, and an annual incidence of adjacent segment disease requiring surgery in 2.5–3.9%, it is clear that a more critical approach is needed with regard to indications for fusion surgery in this patient population.This of course raises the question whether there might be treatment alternatives with a more favorable risk-benefit ratio.

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account as part of any benefit-risk analysis prior to surgery. After analyzing data from 162 studies identified as dealing with this particular issue, ameta-analysis published in 2012 came to a similar conclusion. (58) Among the risk factors associated with adjacent segment disease requiring surgery were the age of the patient (> 60 years), presence of spondylosis deformans or degenerative disc disease in the adjacent segment, multilevel fusions, fusions above L5–S1 and total laminectomy. All these risk factors are very common in spinal stenosis patients. (58) The question whether adjacent segment disease is induced or accelerated by the fusion procedure or whether it represents the natural course of spinal degeneration still lacks a clear

answer. However, a comparative analysis of radiographical evidence of clinically relevant adjacent segment disease in patients undergoing fusion surgery vs. patients not undergoing surgery (59), showed radiographic and clinically relevant adjacent segment disease considerably more frequently in patients who had undergone fusion surgery (12.7–51.3% after 4–12.6 years). (59) Adjacent segment disease appears unrelated to the indication for spinalfusion surgery, with the cumulative incidence of adjacent segment disease following fusion surgery in patients with adolescent idiopathic scoliosis being almost identical to that found in patients with degenerative disease. (59, 60)

author n follow-up (y) Reop

Malter A et al. Spine 23:814-820,1998 (50) 1041 5 18.2%

Ciol AA et al. Spine 19:1329-1334,1994 (51) ? 4 11.9%

Taylor VM et al. Spine 21:2255-2259,1996 (52) ? 3 12.5%

Brook IM et al Spine 32:382-387,2007 (53) 2345 11 21.5%

Gillet P, J Spinal DisordTech 16:338-345,2003 (54) 106 15 20%

Ghiselli G et al, JBJS (Am) 86:1497-1503,2004 (55) 215 6 27.4%

author n follow-up (y) Reop

Jansson KA et al, Eur Spine J 14:659-663,2005 (36) 9664 11 11%

Nasca R , Spine 14:451-454,1989 (35) 114 > 2 J 7%

Deyo RA et al, Spine 18:1463-1470,1993 (45) 1524 4 11.9%

Brook IM et al Spine 32:382-387,2007 (53) 2345 11 21.5%

Similar rates are seen following fusion surgery in large groups of patients with spinal stenosis.

Reoperation rates following fusion surgery (all types)

Reoperation rates following fusion surgery (in spinal stenosis)


2020 Treatment pathways in lumbar spinal stenosis

Take HoMe Message

With regard to different methods of stabilizing the lumbar spine following decompression, interspinous spacers - spacers that are anchored by wrapping tension bands around the spinous processes - are associated with a lower complication rate than pedicle screw-based spinal stabilization systems. However, clear indications for this type of surgery are yet to be defined. In addition, a complete lack of data from prospective, randomized or sufficiently controlled studies means that there is only low-quality evidence (level of evidence IV/V) from small case series available.Similar issues apply in relation to pedicle screw systems used for dynamic stabilization. Screw loosening and/or reoperation rates are likely to be significant, particularly in older patients with spinal stenosis and poor bone quality. The spectrum of possible indications is not clearly defined, particularly in relation to patients who also present with translational instability and/or deformation.

Direct decompression + dynamic stabilization using ligament devices or pedicle screws

The treatment options described previously - which combine spinal fusion and segmental decompression - all carry certain disadvantages. As a result, research over the past few years has focused on finding other treatment options that also pose less of a risk to the patient. The development of interspinous spacers - spacers that are anchored by wrapping artificial ligaments around the dorsal spinous processes - has been particularly relevant in this regard, with the WALLIS and DIAM implants (61,62,63,64), the best-known examples. The main advantage of these types of spacers is the fact that fixation does not require the use of pedicle screws.Although the procedures involved are more invasive than decompression alone, they are less invasive in terms of radiation exposure and surgical approach (posterior approach).

However, there is currently no international consensus - or robust scientific evidence - regarding surgical indications (stand-alone spacer or an adjunct to spinal fusion; prevention of recurrent spinal disc herniation; discogenic low back pain). (65,

66, 67, 68) The same also applies to a number of pedicle screw systems used for dynamic stabilization.

Procedures involving pedicle screw systems are comparable to spinal fusion in terms of their invasiveness and the risks associated with pedicle screw placement.While case series have been reported as showing satisfactory outcomes and/or results comparable to those achieved by spinal fusion surgery (69,70,71,72,73,74), other studies have reported high screw loosening and reoperation rates. (75,76,77)

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Take HoMe Message

Recently published data suggest that direct decompression followed by stabilization using coflex® is an effective treatment for patients with spinal stenosis and predominant back pain. In addition to addressing the cause of the patient‘s back pain and producing clinical outcomes that are comparable to those of spinal fusion, this treatment also causes less trauma to the patient. Normal spinal motion is preserved in both the treated and adjacent segments.

Direct decompression + dynamic stabilization using interspinous/interlaminar spacers

Aside from screw-based procedures, treatment options for the dynamic stabilization of the spine following microsurgical decompression also include interspinous or interlaminar devices, which allow one or two-level stabilization without the need for screw-based posterior stabilization devices. These types of implant - which include the coflex® (Paradigm Spine) and Stenofix (Synthes) devices - provide stability in the affected segments of the spinal column following decompression surgery, whilst maintaining foraminal height and relieving pressure on the facet joints. In addition to addressing the cause of the patient‘s (arthrogenic

and discogenic) back pain, these devices are intended to preserve a near-normal range of motion in adjacent segments.The effectiveness of the coflex® device has been confirmed in a prospective, randomized controlled study by Davis et al., which was published in August 2013

(30) and compared decompression and the coflex® interlaminar spacer with decompression and posterolateral fusion in patients with spinal stenosis and back pain. While coflex® matched spinal fusion in terms of the clinical outcomes measured, it was similar in terms of adverse events, with the less invasive nature of the coflex® procedure resulting in a significant reduction in perioperative morbidity.At 2 years‘ follow-up, spinal fusion was associated with a threefold increase in the reoperation rate at adjacent levels and a considerable increase in motion of the adjacent segments.

LeveL of evIDence



I







RoM Above Level of Implant (degrees)

7.00

6.00

5.00

4.00

3.00

2.00

1.00

0.00

Pre-Op W 6 M 3 M 6 M 12 M 18 M 24

52% Increase

* *

fusion coflex®

* fusion not evaluated

fusion vs. coflex®Pre-opp-value = 0.222

fusion vs. coflex®Month 24p-value = 0.002

fusion vs. fusionPre-op vs. Month 24p-value = < 0.001

coflex® vs. coflex®Pre-op vs. Month 24p-value = 0.594

fusion coflex®

fusion vs. coflex®

Pre-opp-value = 0.843

fusion vs. coflex®

Month 24p-value = 0.345

fusion vs. fusionPre-op vs. Month 24p-value = < 0.001

coflex® vs. coflex®

Pre-op vs. Month 24p-value = < 0.001

Improvement vas Back Pain90

80

70

60

50

40

30

20

10

0Pre-Op W 6 M 3 M 6 M 12 M 18 M 24

• coflex® maintained physiological adjacent segment kinematics at 24 months whereas fusion led to a 52% increase of adjacent segment kinematics.

• coflex® significantly decreased the degree of back pain.


The investigation was a prospective, randomized, multicenter, concurrently controlled comparison of the coflex® procedure to the current standard of care (posterolateral fusion with autograft and pedicle screw fixation), following surgical decompression in both groups. The objective of this clinical trial was to evaluate the safety and effectiveness of the coflex® device for the treatment of 1 or 2-level lumbar stenosis with or without degenerative spondylolisthesis up to Grade I, from L1–L5, that requires surgical decompression, and in patients with at least moderate impairment in function, who experience relief in flexion from their symptoms of leg/buttocks/groin pain with or without back pain, and who have undergone at least six months of conservative treatment.215 randomized coflex® patients and 107 randomized control patients were enrolled in 21 investigational sites all across the United States. A follow-up rate of nearly 96% underlines the credibility of the study findings. The primary success criteria was centered around measuring safety of the coflex® device (i.e. evaluating reoperations, revisions and major complications) and its effectiveness (i.e. pain and function before and after receiving the coflex® device). The patient had to demonstrate no safety failures and show improvement in pain and function tobe a clinical success.

Inclusion criteria*

• Back pain with neurogenic claudication with at least moderate stenosis (L1 to L5) at 1 or 2 levels• ODI > 40• VAS LBP > 50• Age 40 to 80• Six months conservative care + ≥ 1 epidural injection

Exclusion criteria

• Greater than 2 stenotic levels• Previous fusion or multiple surgeries• BMI > 40• Bone density < –1.0 (Osteopenia/Osteoporosis)• Scoliosis > 25° Cobb Angle• Spondylolisthesis > Grade I• Isthmic spondyloslisthesis

Data collected within the study

• clinical ODI, SF–12, ZCQ, VAS, operative details, demographics, etc. • Radiographic ROM, disc heights, foraminal heights, bone resection analysis, fusion and lack of fusion, fractures, etc.• safety Collection and reporting of any adverse event that occurred during the course of the study

* The scores used during the coflex®-FDA study are questionnaire based scores commonly used in the USA to rate back pain, leg pain, symptom severity and physical function of patients.

oDI Oswestry Disability Indexvas LBP Visual Analog Scale Low Back Painvas LLeg Visual Analog Scale Left Legvas RLeg Visual Analog Scale Right LegZcQ sv Zurich Claudication Questionnaire Symptom SeverityZcQ Pf Zurich Claudication Questionnaire Physical FunctionZcQ sf Zurich Claudication Questionnaire Patient Satisfactionsf-12 Pcs Short Form 12 Health Survey Physical Component Summarysf-12 Mcs Short Form 12 Health Survey Mental Component Summary

The coflex® study - designand execution

The authors of that study, Davis et al, discuss and conclude the following:

Discussion

„This study provides level 1 evidence from a randomized, prospective, multicenter FDA Investigational Device Exemption trial that laminectomy with coflex® interlaminar stabilization provided equivalent or superior outcomes to laminectomy and posterior spinal fusion in the treatment of spinal stenosis and degenerative spondylolisthesis. This study is the first to demonstrate equivalence or superiority with a nonfusion device compared with the “gold standard” lumbar fusion in the treatment of patients with spinal stenosis and low back pain or degenerative spondylolisthesis.Although this study met the FDA-determined a priori success criteria of noninferiority compared with fusion controls, with a similar safety profile and adverse event rate, the coflex® interlaminar device significantly outperformed fusion controls in several notable outcomes, which highlights several distinct advantages of coflex® stabilization compared with fusion. First, perioperative outcomes (hospital LOS, estimated blood loss, and operative times) were significantly reduced with coflex®. On average, for 1-level procedures the average


Take HoMe Message

coflex® interlaminar stabilization led to shorter surgical times, reduced hospital Los, and less blood loss compared with in-strumented spinal fusion for lumbar spinal stenosis with up to grade 1 degenerative spondylolisthesis. at 24 months, significant improvements were seen in the coflex® cohort compared with fusion in all ZcQ subdomains, sf-12 Physical component, and a trend toward significance was seen in oDI. fusions exhibited significantly increased angulation at the superior adja-cent level, and a trend toward significant increase in superior level translation, at 2 years, compared with coflex® interlaminar stabilization.

The coflex® study - design and execution

LeveL of evIDence



I






hospital LOS with the coflex® cohort was 1.14 days shorter than fusion, while for 2-level procedures the difference was 1.99 days. In combination with reduced operative times, the data and literature suggest that there is the potential for reduced resource use and cost savings with coflex® while still achieving the same or better clinical results. (78) A second potential advantage of coflex® compared with fusion is seen in the significantly improved functional and clinical outcomes. At multiple early postoperative time points, the coflex® cohort experienced improved outcomes with respect to ODI, with significance achieved early and 24-month improvements seen in all 3 sub domains of ZCQ, and SF-12 Physical Component. This is most likely attributable to the less-invasive nature of coflex® implantation after laminectomy, which incurs less surgical dissection, less blood loss, and may explain the reduced early postoperative pain profile compared with fusion. [ ... ]" (30)

Conclusion

„In conclusion, the current data demonstrate that coflex® interlaminar stabilization after laminectomy is a viable alternative to lumbar spinal fusion. Advantages in perioperative outcomes, and equivalent or superior 2-year clinical outcomes data were seen with coflex®, while the clinical relevance, if any, of maintained operative and adjacent level motion will need to be studied when longer-term follow-up is available. The safety profile and adverse event rates are similar, with secondary surgery rates that are equivalent to that of fusion reported in the literature. [ ... ] We conclude that coflex® interlaminar stabilization is a safe, efficacious, and viable alternative to spinal fusion and an adjunct to laminectomy in the treatment of spinal stenosis with low back pain and degenerative spondylolisthesis." (30)


Continuum of care for spinal stenosis with and without back painBased on the previously discussed results of the current literature, a continuum of care for the treatment of lumbar spinal stenosis might look like the following graphic:

Patie

nt P

rofil

e

- Intermittent neurogenic claudication


- Mild to moderate stenosis

- At least moderate stenosis


- Severe stenosis

- Insignificant back pain - Insignificant back pain - Insignificant back pain - Significant back pain (> leg pain)

- Significant back pain (> leg pain)

- Dominant back pain

- Early or infrequent symptomatology

- Too sick for general anesthesia

- No instability - Stable spondylolisthesis up to 15%

- Unstable spondylosisthesis > Grade I

- Degenerative lumbar scoliosis ≤ 25° Cobb Angle

- Degenerative lumbar scoliosis > 25° Cobb Angle

- Unstable isthmic spondylolisthesis

Trea

tmen

t

- Modification of daily activities

- Indirect decompression - Direct decompression - Direct decompression + coflex® - Direct decompression + fusion

- Interspinous distraction

Stab

iliza

tion

Back Pain

Instability

Leg Pain


Continuum of care for lumbar spinal stenosis with and without back pain

Continuum of care for spinal stenosis with and without back pain

Patie

nt P

rofil

e



- Mild to moderate stenosis



- Severe stenosis

- Insignificant back pain - Insignificant back pain - Insignificant back pain - Significant back pain (> leg pain)

- Significant back pain (> leg pain)

- Dominant back pain

- Early or infrequent symptomatology

- Too sick for general anesthesia

- No instability - Stable spondylolisthesis up to 15%

- Unstable spondylosisthesis > Grade I

- Degenerative lumbar scoliosis ≤ 25° Cobb Angle

- Degenerative lumbar scoliosis > 25° Cobb Angle

- Unstable isthmic spondylolisthesis

Trea

tmen

t

- Modification of daily activities

- Indirect decompression - Direct decompression - Direct decompression + coflex® - Direct decompression + fusion

- Interspinous distraction

Stab

iliza

tion


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Notes


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By Prof. Dr. H. Michael Mayer - ms T · Content The pathology of spinal stenosis 4 The treatment of spinal stenosis 6 Spinal stenosis treatment options and outcomes 8 Conservative