» Discogenic Back Pain and Spinal Fusion: Who Gets Better?

There are 3 things to know about any form of treatment for back pain:

Everything works for someone
Nothing works for everyone
We often don’t know what will work for whom or the extent to which it will work.

Considering that, in most cases, a completely accurate diagnosis for the cause of back pain cannot be made, (read more about that HERE ) it is no wonder that the results of treatment are so variable. This is particularly true with lumbar spinal fusion.

Lumbar (low back) fusion, despite its risk, expense, and technical “savvy” remains just as unpredictable as any other form of treatment.

There is uncertainty about who should have spinal fusion surgery: This is best illustrated by a 20-fold variation in the rate of such surgery depending on where one lives, and not on the diagnosed problem. (1)
There is uncertainty about what type of spinal fusion surgery to perform . Over the last 20 years, spine surgery research has almost exclusively focused on developing new techniques and not on defining what type of patient they are best suited for. (2)
There are even doubts about low back fusion being better than routine conservative care . One study found that lumbar fusion was no better than behavioral intervention and exercises. (3) Another concluded that, “long term outcomes for patients with back pain and concordant discography did not demonstrate a significant difference in outcomes of pain, health status, satisfaction, or disability based on whether the patient elected for fusion or non-operative treatment.” (4)

Undeterred by these lingering doubts, the business of spinal fusion continues to grow.

Since 1998, the number of lumbar fusions has almost tripled and their national cost has increased by a factor of 8x. (5)
This is even worse in Florida, where spinal fusions have increased 16-fold since 1992 and their average case cost has grown from $40,996 to $111,662. Even more alarming is that more than half of the cases performed in 2012 were considered to be of questionable medical necessity. (6)

There are 4 main reasons why predicting lumbar fusion outcomes are difficult.

Clinical diagnosis is imprecise. Several studies have shown that, in most cases, a structural source of spinal pain cannot be defined by either the type of pain experienced or the results of clinical examination procedures that are typically used. (7,8). This was discussed above and you can read more HERE.
The question of which lumbar MRI findings that should be used to guide surgery remains unanswered. (9) Interpreting lumbar MRI findings, in relationship to the need for fusion surgery, becomes even more complicated when one recognizes that similar MRI abnormalities are also seen in completely symptom-free people. (10,11)
The research on lumbar fusion is like Forest Gump’s “box of chocolates”. By this I mean it is very heterogenous. It is dissimilar in the criteria used to select patients for surgery, the type of fusion surgery performed, and the criteria used to define a surgical “success.” This situation has caused one researcher to conclude, “Rather than clarifying what, if any, indications for surgery exist, investigators in the field continue to analyze variations in surgical technique, which will probably have relatively little impact on patient outcomes. As a result, clinicians, unfortunately, have little evidence to advise patients regarding surgical intervention.” (2)
Not enough attention is given to the behavioral and psychological aspects of pain. Numerous studies have shown that individual behavioral and psychosocial factors are stronger predictors of poor treatment outcomes and chronic pain, than are imaging findings or “mechanical” factors. (12,13,14). This has even been demonstrated in individuals who have a clear diagnosis and definitive treatment. (15). Largely because of this overemphasis on the “structural” cause of back pain, to the exclusion of a person’s psychology, calls for a “de-medicalized” approach have been made. (16)

2 studies are worth considering when seeking to predict outcomes of spinal fusion surgery for lumbar discogenic pain.

Lumbar Disc Space Collapse May Predict Spinal Fusion Outcomes.

Studying presumed lumbar discogenic pain; Djurasovic et al. (17) revisited whether or not certain abnormalities on a lumbar MRI could predict a successful lumbar fusion outcome. They found one. The only finding that correlated with a good response to lumbar fusion (and by a large margin) was if the lumbar disc space height was less than 5 mm. Surgical outcomes worsened as the size of the disc space increased, regardless of any other abnormalities that may have been present. Consistent with many other studies on back pain, MRI, and surgical outcomes, they further noted that, “Our study would suggest that many commonly used MRI findings are not reliable markers of who will improve after surgery.”

It should be noted that this is not the first article to suggest such a relationship. A prior study by Hagg et al (18) showed that lumbar disc space narrowing and a personality characterized by low neuroticism were the only factors predicting improvement with fusion for low back pain. The importance of behavioral and psychological factors in back pain treatment results was also discussed earlier in this post.

Outcomes of Transverse Lumbar Interbody Fusion (TLIF) using strict diagnostic criteria provides insight into prognosis.

Corenman et al. (19) looked at surgical fusion in a way that potentially offers more usable information than other similar studies. What they did differently was:

Used a very strict set of criteria to arrive at a diagnosis of lumbar discogenic pain. Among other things, this included patient’s having to show NO benefit from pain relieving injections given to other possible sources of spinal pain and showing significant worsening of pain when the spine was “loaded” and marked improvement in pain at rest.
Studied only one form of lumbar spinal fusion (TLIF) using bone morphogenetic protein (BMP), a substance designed to augment the fusion.
Evaluated outcomes that most people would consider important. (improvement of pain, improvement of function, return to work broken down according to job demands, and adverse effects from the surgery)

The main limitation of this research was that only 45 patients were studied, reducing its statistical power. It also looked at patients having single and double level surgery. However, despite the low statistical power, I still believe that the reported outcomes offer some insight into “predictability”, especially because of the stringent criteria used to determine surgical indications. The outcomes of those patients who had follow up visits at an average of 42 months revealed the following:

84% were able to return to their pre-operative job with or without some limitations. This included 7/7 in the heavy work group and 20/25 in the light work group.
Revision surgery due to peri-operative complications was needed in 4/36.
The average reduction in pre-operative low back pain was 50%.
Physical function scores improved an average of 42%.

Considering the strict criteria used for surgical selection, I would consider these average outcomes as very reasonable expectations when one contemplates TLIF surgery for presumed lumbar discogenic pain.

In summary:

The outcomes for many surgical procedures are unpredictable, largely because research specific to the procedure and using clear diagnostic criteria are lacking.
The best chance for a favorable outcome will likely occur when diagnosis is more precise, and based upon factors that have prognostic significance.
At present, many surgeries are still performed relying upon MRI findings that may have little clinical significance. An exception to this, could be a severe reduction to less than 5 mm of the lumbar disc space.
As with all forms of treatment, the behavioral and psychological make up of each individual plays at least as much of a role in outcomes as does any clinical finding.

For more in-depth information, you can go to the HOME page and download a free copy of my e-book, “Who’s Got Your Back” to learn the importance of obtaining reliable and impartial guidance in your spine-care decisions.

REFERENCES:

Weinstein, Lurie, et al. United States Trends and Regional Variations in Lumbar Spine Surgery: 1992-2003. Spine 2006 Nov. 1;31(23)
Andrade NS, Flynn JP, Bartanusz V. Twenty-year perspective of randomized controlled trials for surgery of chronic nonspecific low back pain: citation bias and tangential knowledge. Spine J 2013 Sept 5.
Brox, Nygaard et al. Four-year follow-up of surgical versus non-surgical therapy for chronic low back pain. Ann Rheum Dis. 2010;69
Smith JS, Sidhu G, et al. Operative and Nonoperative Treatment Approaches for Lumbar Degenerative Disc Disease Have Similar Long-Term Clinical Outcomes Among Patients with Positive Discography. World Neurosurg, 2013. Sept 15.
Rajaee SS, Bae HW et al. Spinal Fusion in the United States: Analysis of trends from 1998-2008. Spine 2012 Jan 1: 37(1)
A Florida Case Study in Surgical Necessity. Washington Post Oct. 2013
Rubinstein and van Tulder. A best-evidence review of diagnostic procedures for neck and low back pain. Best Practice & Clinical Rheumatology Vol. 22, No. 3
May et al. Reliability of procedures used in the physical examination of non-specific low back pain: A systematic review. Aust J Physiother 2006 Vol. 52. No. 2
Djurasovic et al. The influence of preoperative MRI findings on lumbar fusion clinical outcomes. Eur Spine J. 2012;21
Booden et al. Abnormal magnetic resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am 190; 72A
Jarvik JJ et al. The longitudinal assessment of imaging and disability of the back. Spine 2001;26
Jones GT et al. Predictors of low back pain in British schoolchildren: a population-based cohort study. Pediatrics 2003
Jones EA et al. What characterizes persons who do not report musculoskeletal pain? Results from a 4-year population-based longitudinal study. J. Rheumatol 36(5)
Campbell CM, Edwards RR. Mind-body interactions in pain: the neurophysiology of anxious and catastrophic pain-related thoughts. Transl Res 2009; 153
Voorhies RM et al. Predicting outcome in the surgical treatment of lumbar radiculopathy using the Pain Drawing Score McGill Short From Pain Questionnaire, and risk factors including psychosocial issues and axial joint pain. Spine J. 2007;7
Deyo R et al. Over-treating Chronic Back Pain: Time to Back Off? JABFM Jan-Feb. 2009. Vol. 22, No. 1
Djurasovic M et al. The influence of preoperative MRI findings on lumbar fusion clinical outcomes. Eur Spine J. 2012;21
Hagg O et al. Predictors of outcome in fusion surgery for chronic low back pain. A report from the Swedish lumbar spine study. Eur Spine J. 12;22-33
Corneman DS et al. Recombinant Human Bone Morphogenetic Protein-2-Augmented Fusion for the Treatment of Chronic Low Back Pain Secondary to the Homogenous Diagnosis of Discogenic Pain Syndrome.

Discogenic Back Pain and Spinal Fusion: Who Gets Better?