The problem of non-specific low back pain:

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Chronic lower back pain is a symptom, not a diagnosis, and no operative intervention should proceed without a diagnosis. It is akin to operating blindly on an abdomen for stomach pain or performing a brain procedure for headaches without a cause.

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There has been recent written and visual media calling for the regulation of spinal fusion for non-specific and uncomplicated low back pain. The implication for patients who have ‘uncomplicated axial low back pain’ who do not have a surgically correctable lesion diagnosed and have failed initial non-operative care is that they are unlikely to benefit from open surgery. In this instance, it is agreed that surgery and its sequelae are unjustified and a waste of resources as well as posing risk to the patient - indeed the MBS reflects this per the picture below. These patients are more likely to benefit from functional multidisciplinary rehabilitation which may include rehabilitation physicians, pain specialists, rheumatologists and psychologists/psychiatrists (with or without chiropractic) working in concert with their general practitioner. Allied health involvement with physiotherapy/exercise physiology and possibly psychology for psychoneuroeducation is important. Particularly in the case of patients with central sensitisation, this is critical, as outcomes from surgery and interventions generally are poor without consideration.

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An example of a scenario where the correct approach does not occur and could lead to poorer outcomes is where evidence of degenerative disc disease is seen on imaging such as a CT or MRI and operated upon based on the patient having low back pain without an attempt to confirm which structure or level(s) are responsible for the patient’s predominant presentation. This approach is flawed as it does not precisely characterise the pain generators which can be multiple and areas which may appear the most pathological on imaging are not necessarily the correct pain generator for the patient (Colhoun 1988; Osti & Fraser 1992). For example, a surgeon may choose to fuse the L5/S1 intervertebral space based upon patient reports of axial back pain and a disc that appears the most pathological on MRI. However, the patient’s pain here could emanate from multiple sources including the L4/5 disc or the sacroiliac joint(s) (Sembrano & Polly 2009; Young, Aprill & Laslett 2003). Unsurprisingly, a fusion here would not help the patient but is likely to worsen their symptoms as fusion adjacent to diseased structures can increase mechanical shear stress and the spinal fusion surgery is then labelled as ‘failed back syndrome’ incorrectly. This highlights the need for a precision diagnosis of the patient’s pain generator.

Uncomplicated as a term implies a benign condition where there is no underlying structural, neurological or serious medical impairment. As such, the term uncomplicated would not apply to the following conditions:

• ‘Red flag’ conditions such as tumor, fracture, infection or congenital progressive conditions such as hemivertebrae

• Patients with clinical or electrodiagnostic proven chronic radiculopathy

• Patients with imaging proven deformity e.g. sagittal or coronal plane deformities with or without compensatory changes.

• Patients with structural instability such as spondylolisthesis, pars defects, retrolisthesis

• Patients with previous spinal operations presenting with adjacent segment disease to a previous fusion or decompression procedure including proximal or distal junctional kyphosis.

It is arguable whether patients with internal disc disruption and discogenic back pain without radiculopathy should be considered uncomplicated if they have failed an appropriate period of supervised conservative treatment and are, as a result, are impaired socially, economically and requiring increasing analgesia and healthcare episodes (Seghal & Fortin 2000). Depending on the interpretation of the wording, these people invariably present with high levels of disability and evidence of physical deconditioning in their daily lives which would appropriately be described as low back pain due to internal disc disruption (if so diagnosed).

Spinal fusion is fundamental to many forms of spinal treatment and its removal would not only limit treatment to potentially inappropriate or incomplete techniques of care but would deny effective treatment to many Australians.

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The human intervertebral disc is one of the most studied anatomical structures in medicine and there is myriad of high level of evidence literature (Level I and II) to support the application of spinal fusion in many conditions. While some conditions have lower level evidence supporting their use due to their nature (Tumor, Trauma, Infection), they deserve sensitive treatment in their consideration due to their devastating effect on the patient and the nature of these conditions. Evidence for use of fusion includes but is not limited to:

• Degenerative conditions including confirmed discogenic pain, sacroiliac joint pain and acquired conditions (e.g. spondylolisthesis – ‘slipped vertebrae’)

• Tumor conditions

• Trauma

• Infection

• Paediatric and Adult Deformity (kyphosis, scoliosis, combined deformities)

 

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PREFACE ON SPINAL FUSION

Below is a concise and evolving summary of the evidence supporting the use of spinal fusion. It is a form of treatment that has been shown to reduce pain and disability and improve function in properly selected individuals when performed correctly. Accordingly, with evidence of its clinical utility, it is inappropriate to remove this form of effective treatment. A large portion of Australians, many of them of working age and in gainful employment, could benefit from reconstruction for treatment for their condition, should it arise. Similarly, conditions indicating spinal fusion can afflict the young and vulnerable who without it would be rendered more deformed or disabled, with lost potential for productivity and increasing care requirements. As discussed below, to lump spinal fusion risks, efficacy and cost-effectiveness for all comers without regard to the indication is inappropriate.

It is important to note that spinal fusion (and or disc replacement) on clinical grounds is only appropriate in a minor proportion of patients that fail non-operative treatment and are referred via their GP or other specialists to spinal surgeons. However, a subset of these patients when properly diagnosed (as opposed to treatment for non-specific back pain), optimised and selected can return to a productive life of limited pain and good function rather than a natural history of failed conservative treatment where opioid dependence, psychological morbidity and pain medicine interventions are common. Studies of large cohorts of patients with untreated low back pain tend to steady trajectories over time (Chen et al. Pain 2018).

Dr David Sackett, the pioneer of evidence-based practice, said that evidence-based medicine is “the conscientious, explicit and judicious use of current best evidence in making decisions about the care of the individual patient. It means integrating individual clinical expertise with the best available external clinical evidence from systematic research.” Thus, the absence of unanimous irrefutable level I evidence does not necessarily equal absence of benefit and such is the case with lumbar fusion for disogenic back pain. Equally, sham (placebo) type surgery should not be required to brand surgery efficacious or not where there is already compelling evidence consistently showing benefit and the ethical and physical harms and impracticalities of conducting such research are real considerations.

Please review this concise summary of the literature below as to accurately inform evidence of efficacy.

SPINAL FUSION

1. SPINAL FUSION AND DISC REPLACEMENT FOR DEGENERATIVE AND ACQUIRED CONDITIONS (LUMBAR/CERVICAL)

Overall synthesised evidence in the literature supports the effectiveness of fusion for spine surgery in degenerative lumbar conditions (Phillips et al. 2013). For some of these conditions, it is important to note that non-operative treatment is rarely appropriate and consequently have limited comparative studies – a prime example of this is cervical fusion for myelopathy (spinal cord compression) – many would view this as an absolute indication for surgery.

Two of the four randomised controlled trials for ‘chronic low back pain’ (as opposed to a specific diagnosis of discogenic back pain) were inadequately designed to support their conclusion. They did not properly confirm the diagnosis (of discogenic back pain), had mixed surgical techniques (some of them outdated in modern spine surgery such as posterolateral fusion without interbody fusion) for fusion or failed to confirm the presence of fusion on imaging (as was intended) – these have been used to suggest that fusion for ‘back pain’ is ineffective [Knox 2003; Fairbank 2005] where there was only marginal, non-clinically important benefits favoring surgery over conventional medical management.

Conversely, there were 2 RCTs that established the superiority of surgery in alleviating back pain due to discogenic pain compared to non-operative treatment methods [Fritzell 2001; Ohtori 2010]. There was a non-randomized cohort study completed comparing anterior lumbar interbody fusion to medical management finding compelling improvements in pain and function favoring surgery for degenerative disc disease (Kleimeyer et al 2018).

There is also registry data demonstrating clinical efficacy of surgical treatment of degenerative disc disease and discogenic pain when comparing pre- and postoperative patient reported outcome scores – regarded by some as level I evidence – in multiple countries including Sweden (SweSpine), Switzerland (SwissSpine) and the New Zealand Joint Replacement Registry.There are also level II cohort studies also support the use of fusion in degenerative conditions compared to nonoperative treatment for symptomatic disc-related back pain. (Radcliff 2015, Mirza 2013).

Spondylolisthesis is a common subset of patients with back pain related to instability (occult or overt) from a variety of causes. There is compelling evidence in the utility of fusion compared to non-operative treatment for this indication including the SPORT trial [Weinstein 2007] and 3 further RCTs [Moller 2000/Ekmann 2005/Malvimaara 2007]. In fact, the SPORT trial group reported longterm followup in 2018 demonstrating continued benefit at 8 years [Abdu 2018 Spine].

Regarding fusion for spondylolisthesis compared to decompression alone, synthesis of the literature shows superiority for combined fusion and decompression including a RCT (Ghogawala SLIP STUDY NEJM 2016) and an increased risk of re-operation for decompression alone versus fusion [Yavin 2017 Neurosurgery]. Despite the study of Firth et al. 2016 NEJM (Swedish spine group) not finding significant benefit of the addition of fusion over decompression alone at 2 years for spinal stenosis, multiple studies support the routine inclusion of fusion as the standard of care for spondylolisthesis with/without spinal stenosis (Kornblum 2004; Bridwell 1993; Vaccaro 1997; Martin 2007).

 

 

A small subset of patients will have recalcitrant back and/or leg symptoms (typically radiculopathy) following prior posterior discectomy or laminectomy procedures and have recurrent prolapse or stenosis. There is some limited evidence that fusion in these patients yield more predictable outcomes than another discectomy or decompressive procedure where further damage to muscle and neurological scarring from retraction is typical (Greenleaf, Harris and Bono 2011).

Sacroiliac joint fusion is another subset of so-called ‘low back pain’ related spinal fusion procedures. Low back pain when systematically diagnosed and attributed to sacroiliac joint disease has been shown to be improved by sacroiliac joint fusion when compared to non-operative treatment [Polly 2015]

Modern spinal surgery literature has shown that in the cervical spine, posterior decompression alone procedures (ie laminectomy or foraminotomy) lead to poor outcomes and high rates of instability for segmental degenerative pathology compared to the rates reported in fusion or motion preserving procedures (Guigui 1998; Herkowitz 1990; Mikawa 1987). Cervical degenerative disc disease with related radiculopathy (nerve root related dysfunction) has been shown to have superior outcomes when treated with fusion surgery (cervical discectomy and fusion) and a supervised exercise compared to physiotherapy alone (Engquist 2017). While there is evidence to support a conservative approach for cervical radiculopathy without motor loss, there is no evidence to support the prescription of non-operative care once myelopathy is diagnosed thus, there is essentially no evidence comparing fusion to nonoperative treatment for this latter indication (Rhee Spine 2013).

This piece relates to fusion rather than all forms of spinal surgery but there is also level I evidence from the SPORT and Canadian papers on effectiveness of decompression versus conservative medical management.

 

It is incorrect to group the efficacy of fusion in the same evidence category, and therefore private health categorisation, as lumbar disc replacement for discogenic source confirmed axial back pain or cervical disc replacement for radiculopathy. There are a limited number of candidates for fusion who are also candidates for TDR. Disc replacement has had only limited comparisons to non-operative treatment but has shown statistical differences albeit clinically minor in improvement of back pain compared to intensive rehabilitation (Hellum et al. 2011) and further high quality level I studies comparing disc replacement to non-operative treatment are required. There are several level I studies, however, comparing different types of lumbar fusions to disc prostheses and syntheses of these data that show at least equivalent outcomes but in many, superior outcomes, return to work and function are achievable with the use of lumbar disc prostheses (Zigler et al. 2017; Mattei et al 2017). There is also emerging data from multiple RCTs to support at least equivalence if not superiority of cervical TDR over fusion (Wang et al. 2023)

 

2. SPINAL SURGERY INCLUDING FUSION FOR DEFORMITY      

Spinal fusion is the cornerstone of current techniques for correcting adult deformity conditions. Operative treatment has been shown to have superior quality of life improvements compared to non-operatively treated patients in a prospective multicentre cohort trial (International Spine Study group 2016 Neurosurgery). It has also been shown to be cost-effective compared to non-operative care in terms of quality of life years gained in the medium to long-term (McCarthy et al. 2014)

Cohort studies of Bridwell et al. (2009) and Li et al. (2009) both compared operative (constructs including fusion) and non-operative care in de novo scoliosis patients, a common adult deformity, demonstrating reduced pain and improved quality of life compared to nonoperative care. Adult patients with kyphosis also benefit from fusion as part of their corrective surgery to return them to the normal limits of spinal alignment as this correlates with outcome scores and quality of life (Terran et al. 2013)

Fusion in paediatric conditions most commonly relates to spinal deformity and instability in the form of upper cervical (e.g. atlantoaxial instability), thoracolumbar kyphosis and scoliosis and spondylolisthesis. While some milder and less morbid conditions (e.g. mild adolescent idiopathic scoliosis caught before growth and reaching stiff/large magnitude curve or adolescent mild spondylolisthesis with minor symptoms) are appropriate for bracing and observation (Weinstein 2013 BRAIST Trial NEJM), many of the paediatric conditions are not appropriate for non-operative management and again the difficulty in generating evidence ethically arises here. There is a very wide spectrum of diseases in paediatrics and nonoperative treatment that works for adolescent idiopathic scoliosis has been shown to be ineffective for early onset scoliosis as well as syndromic and neuromuscular conditions (Olaffson et al. 1999). Progression of deformity and loss of neurological function in a very young individual is the consequence of inappropriate prescription of non-operative care.

Understandably, there is also difficulty in constructing high quality level I data for tumors, trauma and infection due to the ethical and logistical difficulty in randomizing patients to different treatment types. However, lower grade evidence supports the efficacy of fusion applied to treating these pathologies.

3. SPINAL SURGERY INCLUDING FUSION FOR TRAUMA

There is a high level of evidence to support operative intervention for unstable thoracolumbar and cervical fractures (Scheer 2014).

Fusion either intervertebral or vertebrectomy with cage is indicated in cervical fractures with instability and neurological loss. Non-operative treatment in these situations is associated with inferior results (Gelb et al. 2013).

There is some controversy as to the role of short segment fusion in the management of thoracolumbar fractures that would otherwise be managed by pedicle screw fixation alone (Qian 2006; Dai 2009). Posterior instrumentation in these patients without fusion has been shown to lead to satisfactory results. However, there is a subset of patients with severely comminuted anterior column injuries that benefit from fusion in anterior reconstruction in reducing late collapse/deformity and increasing healing rates (Korovessis et al.  2006; Schnake et al. 2014)

 

4. SPINAL SURGERY INCLUDING FUSION FOR TUMORS

Patients with spinal tumors are a unique and diverse subgroup of patients where the indication for surgery varies widely but relates to pain, instability and poor function more commonly than curative attempts at increased survival (Kim et al. 2011). As such they are a difficult group to study for evidence purposes and there are limited studies with comparison to other treatments in big enough numbers for meaningful conclusions for obvious reasons. Adjudged ability of spinal surgery to achieve pain reduction, limit functional loss (e.g. bladder/bowels) and quality of life on an individual basis with clinician experience should direct care here in the face of low level evidence.

For many years, spinal cancer was treated palliatively with or without radiation and chemotherapy. However, landmark the studies of Patchell et al. (2005) as well as Holman et al. (2005) established the utility of decompression (with or without stabilisation) for tumors in improving pain, function and quality of life even in metastatic cancers. Vertebral bodies severely affected by disease that have not responded to conservative measures such as radiotherapy and chemotherapy and are causing instability, deformity or neurological damage can benefit from vertebrectomy and reconstruction (Goskalan 1998 Neurosurgery).

Tumor resection for potentially curable lesions has been shown to increase survival in selected neoplasms (sarcomas) and requires fusion and stabilisation in reconstruction (Krepler et al. 2002). This was demonstrated in studies by the osteosarcoma cooperative study group where wide excision improved survival (Ozaki et al. 2002). Essentially, without spinal fusion and reconstruction any attempts at curative treatment by surgical excision will likely be compromised (in terms of tumor recurrence) and complicated by secondary issues including instability, neurological loss and pain (Hart et al. 1997).

 

5. SPINAL SURGERY INCLUDING FUSION FOR INFECTION

The role of fusion in infection relates to reconstruction and stabilisation of the spinal column when severely affected by infection despite medical therapy or when the required decompression causes instability. This population is similar to the tumor population in this regard (Kim et al. 2011) and can present with rapid onset and dramatic neurological loss. Again there are no higher level evidence comparative studies for this indication but there are level III-IV studies supporting fusion either in initial treatment or reconstruction. Aggressive surgical treatment incorporating fusion has been shown to be effective in this regard and improve neurology in the majority of patients (Gorensek et al. 2012; Shousha & Boehm 2012).

For instance, severely diseased vertebral bodies that have not responded to antibiotics and are causing instability, deformity or neurological damage can benefit from vertebrectomy and reconstruction (Gorensek et al. 2012; Kim et al. 2011). This includes not only infections commonly seen in Australia but also atypical infections such as tuberculosis where secondary spine deformity is common (Talu et al. 2006).

 

6. ECONOMIC AND SOCIETAL IMPACTS:

Health Economic aspects relating to surgery for appropriately selected and diagnosed patients with predominant degenerative low back pain (as opposed to surgery for deformity, trauma, tumor, infection, neural involvement) should be considered.

• EMPLOYMENT: For all comers, there a several studies which demonstrate a satisfactory rate of long-term return to gainful employment – generally increased compared to pre-operative (Wang et al. 2017; Fayssoux et al. 2010).

• NARCOTIC/OPIOID USE: Excluding patients who were longterm dependent on narcotics (known to be strongly associated with postoperative use), a large USA database study showed that 9.1% of patients who were dependent on narcotics became narcotic free, 87.1% who were narcotic independent remained independent while only 3.8% became narcotic dependent. Wang and colleagues (2017) in a recent systematic review of papers reporting opioid use after lumbar fusion reported reduced narcotic usage post-operatively in the majority of studies.

• QUALITY OF LIFE ADJUSTED YEARS – Australian studies have shown favourable cost effectiveness of lumbar fusion for low back pain due to spondylolisthesis - McCombe; Sears Mohktour 2010. In fact, this is similar to large joint replacements where total hip replacement is considered one of the most successful operations in all of medicine and comparable quality of life the population of similar age. The SPORT trial provided an RCT of cost effectiveness of fusion for lumbar spondylolisthesis and other studies, for example single level posterolateral fusion, have also been reported (Glassman 2012 Spine).

• HEALTHCARE EPISODES

• These outcomes have not been extensively studied in Australia as applied to discogenic back pain or sacroiliac joint pain but there are Australian studies (Parkinson et al 2012) which report return to work in the order of 80-90% and a reduced requirement for morphine based derivatives (Mobbs, Malham, Seex, + Scott-Young et al. 2012). Patients with compensable / litigious injuries and patients on longterm narcotics should be considered separately as these factors are known to affect outcomes.

 

Comments on optimal pre and post surgical care that can influence outcomes and their evaluation:

Pre-operatively these patients require a clear precision diagnosis (see above), a period of appropriate supervised non-operative care and have had a multi-disciplinary assessment prior to fusion. The latter includes profiling and optimising comorbidities by a suitable perioperative physician or anaesthetist, perioperative conditioning with physiotherapy and (if indicated) review by a mental health professional or pain physician if there are concerns over psychosocial or patient factors [including opioid use] that could compromise outcome (LaCaille et al. 2005).

The literature is clear that inclusion of interbody devices in the fusion are the most effective form of treatment due to discogenic back pain (Barrick et al. 2000; Weatherley 1986; Greenough et al. 1998). Furthermore, treatment of degenerative disc disease via the standalone anterior approach for suitable candidates has been associated with superior outcomes in reported literature when compared to other approaches (Mummameni et al. 2014; Greenough et al. 1998; Connolly et al. 2017). As such, if an anterior interbody placing approach is selected for a patient with discogenic back pain for either fusion or disc replacement, assuming there are no other contraindications, then involvement of a vascular surgeon for surgeons unfamiliar with vascular mobilisation or repair techniques (with or without imaging of any pathological vessels) should be encouraged.

Post-operatively, other than routine hospital care, structured rehabilitation to maintain the patient’s movement and musculature has been a successfully employed approach (Green et al. 2015; Canbulat et al. 2011) and is based upon principles that patients with relative disuse are affected by impaired trunk control, proprioception and muscular atrophy and have poorer outcomes (Gu et al. 2016; LeHuec et al. 2005; Storheim et al. 2017).

Patients should be followed to an appropriate time frame given the potential for complications and the structural result should be confirmed. This should be done with CT scanning (to validate fusion or incorporation of implant), standing alignment imaging (such as EOS™) to confirm satisfactory correction and alignment and flexion/extension imaging (if a motion preserving device has been used). Some of the studies which have shown surgery was equivocal with non-operative treatment for undiagnosed low back pain also did not confirm the result of the planned surgery i.e. confirm solid bony fusion or satisfactory sagittal alignment following fusion surgery (Brox et al. 2003; Fairbank et al. 2005).

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Why are spinal fusion outcomes so inconsistent and how can we improve consistency?

What steps should spinal surgeons take to optimise outcomes and ensure correct procedure and patient selection?

Suggestions:

• Ensuring attempts at the correct diagnosis have been made through investigations and the addition of testing the suspected pain generators e.g. discography in the case of suspected discogenic back pain or sacroiliac/facet joint block for suspected sacro-iliac or facet pain; SPECT and MR spectroscopy scans have also been reported to have clinical utility through high sensitivity in ruling out the disc as a pain generator; Electrodiagnostic testing indirectly suggests significant disc pathology if radiculopathy is diagnosed through the effect of the disc upon the nerves in the spinal canal or neuroforamen.

• Appropriate perioperative care with optimisation through conditioning (physiotherapy), management of comorbidities (physician or general practitioner) and appropriate planning.

• Risk calculators and patient selection tools are important for prognosis of the intervention and expectation management.

• Planning for degenerative lumbosacral conditions should include specific evidence of assessment of pelvic and sagittal parameters – where there is often a ‘hidden deformity’ (Barrey et al. 2011) as the treatment plan is compromised without this (e.g. EOS or standing alignment radiographs). To our knowledge, this has not been routinely undertaken by spinal surgeons and should become the standard of care for appropriate planning and validation of treatment strategy and avoiding creating a deformity by inadequate surgery.

• Interbody devices (either devices intended for fusion or motion-preserving device such as total disc prosthesis) as opposed to posterolateral fusion only strategies should be utilised for discogenic back pain. Posterolateral fusions which do not incorporate interbody devices have been shown to have poorer results (Barrick et al. 2000; Weatherley 1986; Greenough et al. 1998). The case of sacroiliac joint fusion is unique and there are currently several accepted methods to obtain fusion.

• A perioperative plan for rationalisation of opioid medication should be in place with multidisciplinary involvement as required. The spinal surgeon working in conjunction with a chronic pain specialist and the general practitioner would benefit from an agreement or even contract regarding the timeline for opioid withdrawal, as appropriate, and attempts made to scale down dosage prior to surgery given it has been associated with poorer outcomes from surgery (Connolly et al. 2017).

• Surgeons should show evidence of appropriate follow-up of spinal fusion patients and involvement in audit of their spinal outcomes. Involvement in the Australian Spine Surgery registry (recently commenced) should be encouraged.

• Rather than Membership of the Australian Orthopaedic Association or Neurosurgical Society of Australia alone, surgeons intending to continue to perform spinal fusion or disc replacement surgery for degenerative conditions ideally would show both adequate training such as post graduate fellowships and involvement in professional organisations mainly dedicated to spinal care. Examples of this (non-exhaustive) would include Spine Society of Australia, Scoliosis Research Society, International Society for Study of the Lumbar Spine, AO Spine and North American Spine Society.

 

The concern about future management of tens of thousands of Australians with low back pain is  particularly relevant where general practitioners and other healthcare providers charged with looking after patients who have failed conservative treatment with chronic symptoms may have limited choices in the care of these patients. When appropriately selected and performed without reversion to a pattern of longterm disability, spinal surgery can be life-changing for patients and return them to functionality. In limiting access to interventional therapties an increase in disability pension claims, reduction in employment amongst patients of working age and increased referral to rehabilitation, pain specialists and psychiatrists for complex pain care programs can be anticipated without necessarily cost effective commensurate increases in quality adjusted life years (QALY) and 'value'. For those not of working age, decreasing mobility and increased care requirements could be anticipated where, instead, selected patients may be amenable to improvement in their function and symptoms from surgery.