The Open Orthopaedics Journal




ISSN: 1874-3250 ― Volume 13, 2019

Spinal Fusion in the Treatment of Chronic Low Back Pain: Rationale for Improvement



Bo Nyström*
Clinic of Spinal Surgery, Löt, 64594 Strängnäs, Sweden

Abstract

Results following fusion for chronic low back pain (CLBP) are unpredictable and generally not very satisfying. The major reason is the absence of a detailed description of the symptoms of patients with pain, if present, in a motion segment of the spine. Various radiological findings have been attributed to discogenic pain, but if these radiological signs were really true signs of such pain, fusion would have been very successful. If discogenic pain exists, it should be possible to select these patients from all others within the CLBP population. Even if this selection were 100% perfect, however, identification of the painful segment would remain, and at present there is no reliable test for doing so. Regardless of whether an anterior or posterior type of fusion is performed, or even if artificial discs are used, solving the puzzle of pain associated with the presumed segmental disorder must be the primary goal.

Keywords:: Spinal fusion, low back pain, symptoms, discography, pseudarthrosis, artificial disc.


Article Information


Identifiers and Pagination:

Year: 2012
Volume: 6
First Page: 478
Last Page: 481
Publisher Id: TOORTHJ-6-478
DOI: 10.2174/1874325001206010478

Article History:

Received Date: 23/5/2012
Revision Received Date: 5/10/2012
Acceptance Date: 14/10/2012
Electronic publication date: 8/11/2012
Collection year: 2012

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© Bo Nyström; Licensee Bentham Open

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.


* Address correspondence to this author at the Clinic of Spinal Surgery, Löt, 64594 Strängnäs, Sweden; Tel: +46 152 26300; Fax: +46 152 26370; E-mail: bo.nystrom@ryggkirurgiska.se




INTRODUCTION

In cases of pronounced chronic low back pain with or without nonspecific leg pain (CLBP) where the patient does not respond to conservative treatment, a discussion about spinal fusion may ultimately take place. The results following this surgery are varying, controversial and not very satisfying [1 Turner JA, Ersek M, Herron L, et al. Patient outcomes after lumbar spinal fusions JAMA 1992; 268: 907-11.-3 Gibson JNA, Waddell G. Surgery for degenerative lumbar spondylosis: Updated Cochrane review Spine 2005; 30: 2312-0.]. Since the specific indication for fusion in these cases is not yet determined, the question is whether spinal fusion should really be performed [2 Deyo RA, Nachemson A, Mirza SK. Spinal-Fusion surgery – the case for restraint New Eng J Med 2004; 350: 722-6., 4Hanley EN Jr, David SM. Lumbar arthrodesis for the treatment of back pain J Bone Joint Surg Am 1999; 81-A: 716-30.-6 Chou R, Baisden J, Carragee EJ, Resnick DK, Shaffer WO, Loeser JD. Surgery for low back pain. A review of the evidence for an American Pain Society clinical practice guideline Spine 2009; 34: 1094-.].

A number of different conditions may present with symptoms of low back pain. Homogeneous groups of patients, each with a specific reason for their pain, are mixed with other groups of patients whose pain is also of homogeneous origin. Nevertheless, we do not know exactly what these different reasons are for the pain. This could be likened to a situation in which patients are collected under the diagnosis of abdominal pain, but specific disorders such as gall bladder disease, gastric ulcer and appendicitis are not distinguishable. Clearly, a spinal fusion would be of no help in cases of muscular or inflammatory pain or if the pain originates in the sacroiliac joints. Spinal fusion might, however, be of value in facet joint pain, discogenic pain and “instability”, provided these patients could be selected with certainty from the whole population of patients with CLBP.

SELECTION OF PATIENTS, SYMPTOMS

In most reports back pain is never specified, and is referred to simply as chronic low back pain. This is also true in recent randomised studies [7 Fritzell P, Hägg O, Wessberg P, Nordwall A, et al. Volvo award winner in clinical studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain Spine 2001; 26: 2521-34.-10 Brox JI, Reikerås O, Nygaard Ö, et al. Lumbar instrumented fusion compared with cognitive intervention and exercises in patients with chronic back pain after previous surgery for disc herniation: A prospective randomized controlled study Pain 2006; 122: 145-55.]. Analogous with the example of abdominal pain and with the intention of finding a specific pain pattern, back pain ought to be more thoroughly analysed according to localization (lateral or midline), character (diffuse or restricted, continuous or intermittent, dull, burning, stabbing, etc.), and situations that aggravate or alleviate the pain. Similarly, leg pain should be analysed as to whether it is diffuse, radicular, pseudoradicular, dull, burning, continuous or intermittent, and whether it is coupled with numbness or paresthesia. Specific questions about any bladder disturbance such as urinary retention, urgency, hesitancy, or terminal dribbling should also be posed. We have to complete the puzzle regarding pain associated with the condition to be treated using spinal fusion. The ideal condition for this treatment would be pain in one motion segment of the spine, i.e. pain in the motion between two vertebrae, or segmental pain. If such a condition exists, its clinical pain presentation would be the segmental pain syndrome.

RADIOLOGY HAS FAILED

In efforts to select patients suitable for treatment with fusion surgery, radiological findings have not provided a solution. Osteoarthritis of the facet joints is seen as early as at 20 years of age and in almost every person by the age of 50 [11 Eubanks JD, Lee MJ, Cassinelli E, Ahn NU. Prevalence of lumbar facet arthrosis and its relationship to age sex and race Spine 2007; 32: 2058-62., 12 Kalichman L, Li L, Kim DH, et al. Facet joint osteoarthritis and low back pain in the community-based population Spine 2008; 33: 2560-5.], and concentric as well as radiating tears appear even in young discs [13 Vernon-Roberts B, Moore RJ, Fraser RD. The natural history of agerelated disc degeneration The pathology and sequelae of tears Spine 2007; 32: 2797-804.]. Over the years these and other radiological findings such as marked disc degeneration, spondylotic spurs, internal disc disruption and annular tears seen on MRI or discography, high intensity zones and Modic signs have been attributed to low back pain and also more specifically to discogenic pain [14 Macnab I. The traction spur An indicator of segmental instability J Bone Joint Surg Am 1971; 53: 663-70.-17 Braithwaite I, White J, Saifuddin A, Renton P, Taylor BA. Vertebral end-plate (Modic) changes on lumbar spine MRI: correlation with pain reproduction at lumbar discography Eur Spine J 1998; 7: 363-8.]. However, this opinion has been contradicted by others [18 Carragee EJ, Paragioudakis SJ, Khurana S. Volvo award winner in clinical studies. Lumbar high-intensity zone and discography in subjects without low back problems Spine 2000; 25: 2987-92.-20 Hancock MJ, Maher CG, Latimer J, et al. Systematic review of tests to identify the disc SIJ or facet joint as the source of low back pain Eur Spine J 2007; 16: 1539-50.]. If these radiological signs were actually true signs of discogenic pain spinal fusion would have been extremely successful in cases of CLBP because all these signs are easily recognized on plain X-rays, MRI and discography. Since this is not the case, the search for pathoanatomic changes that serve as landmarks of low back pain has so far been unsuccessful. If in some cases the origin of unspecific low back pain is discogenic, which is supported to some extent by the findings of low back pain provocation by direct palpation and pressure on the discs of awake individuals undergoing surgery under local anaesthesia [21 Spurling RG, Grantham EG. Neurologic picture of herniations of the nucleus pulposus in the lower part of the lumbar region Arch Surg 1940; 40: 375-88., 22 Kuslich SD, Ulstrom CL, Michael CJ. The tissue origin of low back pain and sciatica A report of pain response to tissue stimulation during operations on the lumbar spine using local anesthesia Orthop Clin North Am 1991; 22: 181-7.], the question may be posed as to whether there has to be any specific radiological disc abnormality at all.

REPORTED INDICATIONS FOR FUSION

In textbooks and reviews concerning indications for fusion in cases of CLBP the following can be found: translational instability, segmental instability, postlaminectomy syndrome, internal disc disruption, painful disc degeneration, isolated disc resorbtion, persistent low back pain after lumbar discectomy, discogenic back pain, annular tear, failed back syndrome, primary large central disc herniation and recurrent disc herniation [23 Gill K. Clinical indications for lumbar interbody fusion In: Lin PM, Gill K, Eds. Lumbar interbody fusion Principles and techniques in spine surgery. Rockville, Maryland: Aspen publishers 1989; pp. 35-53. Chapter 4, 24 Burkus JK. Interbody fusion devices: Biomechanics and clinical outcomes In: Vaccaro AR, Betz RR, Zeidman SM, Eds. Priciples and practice of spine surgery. USA: Mosby Inc 2003; pp. 385-97. Chapter 30]. The results following spinal fusion surgery with regard to these indications have been reported by Turner et al. [1 Turner JA, Ersek M, Herron L, et al. Patient outcomes after lumbar spinal fusions JAMA 1992; 268: 907-11.] who concluded, ”For several low back disorders no advantage has been demonstrated for fusion over surgery without fusion”. Further, Chou et al. [6 Chou R, Baisden J, Carragee EJ, Resnick DK, Shaffer WO, Loeser JD. Surgery for low back pain. A review of the evidence for an American Pain Society clinical practice guideline Spine 2009; 34: 1094-.] stated recently that “For nonradicular pain with common degenerative changes, fusion is no more effective than intensive rehabilitation.” Only one out of four rather recent randomised studies reported that the results following fusion surgery were better than in the control group [7 Fritzell P, Hägg O, Wessberg P, Nordwall A, et al. Volvo award winner in clinical studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain Spine 2001; 26: 2521-34.-10 Brox JI, Reikerås O, Nygaard Ö, et al. Lumbar instrumented fusion compared with cognitive intervention and exercises in patients with chronic back pain after previous surgery for disc herniation: A prospective randomized controlled study Pain 2006; 122: 145-55.].

We therefore face a situation in which the decision to perform a spinal fusion operation in cases of CLBP is based in most cases only on the presence of chronic low back pain and some very unspecific radiological signs. In every other kind of surgery there is an effort to rely on specific and relevant symptoms for each surgical intervention, e.g. symptoms of appendicitis for appendectomy, of gall bladder disease for cholecystectomy and so on. Abdominal surgery is not generally performed on the indication of diffuse abdominal pain. It is therefore an absolute necessity to search for the clinical symptoms and the pain description indicating a condition that is treatable by spinal fusion, and not to look for various radiological signs.

PINPOINTING THE PAINFUL SEGMENT, IF PRESENT

Logically, provocative discography would be the most suitable test for pinpointing a painful disc, and several reports defend this opinion [16 Aprill C, Bogduk N. High-intensity zone a diagnostic sign of painful lumbar disc on magnetic resonance imaging Br J Radiol 1992; 65: 361-9., 25 Simmons EH, Segil CM. An evaluation of discography in the localization of symptomatic levels in discogenic disease of the spine Clin Orthop Relat Res 1975; 108: 57-69.-27 Zdeblick TA. Discogenic back pain In: Rothman RH, Simeone FA, Eds. The Spine. Philadelphia: WB Saunders 1999; pp. 749-65. Chapter 28] while others do not [26Bogduk N, Modic MT. Controversy. Lumbar discography Spine 1996; 21: 402-., 28 Carragee EJ. Is lumbar discography a determinate of discogenic low back pain provocative discography reconsidered Curr Rev Pain 2000; 4: 301-8., 29 Madan S, Gundanna M, Harley JM, Boeree NR, Sampson M. Does provocative discography screening of discogenic back pain improve surgical outcome? J Spinal Disord Tech 2002; 15: 245-51.]. A positive discographic test is usually based on concordant pain reaction of significant magnitude in one disc that is not found in an adjacent disc [27 Zdeblick TA. Discogenic back pain In: Rothman RH, Simeone FA, Eds. The Spine. Philadelphia: WB Saunders 1999; pp. 749-65. Chapter 28, 30 Merskey H, Bogduk N, Eds. Classification of chronic pain Descriptions of chronic pain syndromes and definitions of pain terms. 2nd ed. USA: IASP Press 1994; pp. 175-206.]. The test has been questioned on the basis that pain may also be provoked during disc injection in normal subjects [31 Holt EP. The question of lumbar discography J Bone Joint Surg 1968; 50A: 720-6.] and in subjects without low back pain but with ongoing chronic pain of non-lumbar origin [32 Carragee EJ, Alamin TF, Carragee JM. Low-pressure positive discography in subjects asymptomatic of significant low back pain illness Spine 2006; 31: 505-9.]. However, by definition these persons should be unable to report about concordance. Similarly, it is difficult to understand how patients with iliac crest pain following bone harvesting can report concordant pain during discography [33 Carragee EJ, Tanner CM, Yang B, Brito JL, Truong T. False-positive findings on lumbar discography. Reliability of subjective concordance assessment during provocative disc injection Spine 1999; 24: 2542-7.]. Early reports on pain provocation at lumbar discography invariably noted that the pain was located in the lumbar spine, but also, in declining frequency, in the buttock, thigh or lower leg [34 Fernström U. A discographical study of ruptured lumbar intervertebral discs Acta Chiru Scand Suppl 1960; ((Suppl 258))1-60.]. A recent report strongly supports the view that a positive provocation test in discography is of little or no value in detecting the pain generator, e.g. the presumed painful disc, if performed in a non-specific group of patients suffering from CLBP [35 Carragee EJ, Lincoln T, Parmar VS, Alamin T. A gold standard evaluation of the ”discogenic pain” diagnosis as determined by provocative discography Spine 2006; 31: 2115-3.]. Whether the disc provocation test would be of value in selecting the pain-generating disc in a homogeneous population of patients actually suffering from discogenic pain is an open question, since no such patient selection has yet been possible on clinical or other grounds. Some other testing techniques have also been developed and used as possible methods for finding the painful segment, if present, including the bony vibration test [36 Yrjämä M, Vanharanta H. Bony vibration stimulation a new noninvasive method for examining intradiscal pain Eur Spine J 1994; 3: 233-5.], but they are apparently not specific enough [20 Hancock MJ, Maher CG, Latimer J, et al. Systematic review of tests to identify the disc SIJ or facet joint as the source of low back pain Eur Spine J 2007; 16: 1539-50.]. The open mechanical provocation test that has been described [37Nyström B. Open mechanical provocation under local anesthesia: a definitive method for locating the focus in painful mechanical disorder of the motion segment In: Fifth international conference on lumbar fusion and stabilization; 1991; Osaka Japan. ] is likewise not validated. In summary, as recently stated by Hancock et al. [20 Hancock MJ, Maher CG, Latimer J, et al. Systematic review of tests to identify the disc SIJ or facet joint as the source of low back pain Eur Spine J 2007; 16: 1539-50.], “The usefulness of all these tests in clinical practice, particularly for guiding treatment selection, remains unclear.”

SEGMENTAL PAIN AND PAIN DISTRIBUTION

If we assume that segmental pain really exists and can express itself clinically in a specific segmental pain syndrome, it would be possible to select these patients from all others within the population suffering from CLBP. Even if this selection of patients were to be 100 % perfect, we would still have to identify the segment producing the pain. Pain might have its origin in one single segment, L3-L4, L4-L5 or L5-S1, but possibly also in two or even three of these segments. Without any reliable test to pinpoint a painful segment [20 Hancock MJ, Maher CG, Latimer J, et al. Systematic review of tests to identify the disc SIJ or facet joint as the source of low back pain Eur Spine J 2007; 16: 1539-50.] the probability of fusing the appropriate painful segment or segments would depend on the distribution of segmental pain at different levels. Let us assume that patients in a given population have segmental discogenic pain localized to only one segment and with an equivalent distribution among the three lower lumbar segments, i.e. one third of the selected patients have their segmental pain at L3-L4, one third have it at L4-L5 and one third at L5-S1 (column A in Fig. 1). In this situation a segmental fusion at a single level would have a 33% probability of curing the patient from his/her low back pain. If we assume another distribution of segmental pain, e.g. 10% with their discogenic pain at L3-L4, 40% at L4-L5 and 50% at L5-S1 (column B in Fig. 1), which probably would be more relevant, a mono-segmental fusion at L5-S1 would have a 50% probability of success, the remaining half of the patient population would have their pain at higher levels. If we add to this discussion the possibility that segmental pain might exist at two levels simultaneously, e.g. in both the L4-L5 and L5-S1 segments, and assume this to be the case in say 20% of the patients, the probability of curing the patient with a mono-segmental fusion declines to 40% in the L5-S1 example just mentioned, since one fifth of these patients would still have pain from the L4-L5 segment. It must be remembered that the prerequisite for these figures is the assumption that it is possible to select all these patients with exclusively segmental pain. If only half of the patients selected truly suffer from discogenic pain, the figures just discussed would decrease by half to around a 20-25% probability of curing the L5-S1 patient discussed above with a mono-segmental fusion, a figure actually found in a well-designed study by Carragee et al. [35 Carragee EJ, Lincoln T, Parmar VS, Alamin T. A gold standard evaluation of the ”discogenic pain” diagnosis as determined by provocative discography Spine 2006; 31: 2115-3.].

Fig. (1)

Examples of different percent distributions, A and B, of segmental pain in the lower lumbar levels in a conceived patient population.



One may argue that a two-level fusion in the example just given, where 40% of the patients had segmental pain at L4-L5 and 50% at L5-S1, would have a 90% chance of success. Two-level fusions, however, are often performed using a postero-lateral technique. Even after successful bony healing this type of fusion may permit some movement in the disc region [38 Johnsson R, Selvik G, Strömqvist B, Sundén G. Mobility of the lower lumbar spine after posterolateral fusion determined by roentgen stereophotogrammetric analysis Spine 1990; 15: 347-50., 39 Rolander SD. Motion of the lumbar spine with special reference to the stabilizing effect of posterior fusion. An experimental study on autopsy specimens Acta Orthop Scand 1966; (Suppl 90)1-144.]. Therefore, if discogenic pain were of a mechanical nature, pain might still exist despite a healed postero-lateral fusion due to the lever arm anterior to the disc, making slight axial movement still possible and thereby the possibility of persisting pain. If discogenic pain really exists, the appropriate fusion would therefore be an interbody fusion [40 Weatherley CR, Prickett CF, O´Brian JP. Discogenic pain persisting despite solid posterior fusion J Bone Joint Surg Br 1986; 68: 142-3.-42 Videbaek TS, Christensen FB, Soegaard R, et al. Circumferential fusion improves outcome in comparison with instrumented posterolateral fusion: Long-term results of a randomized clinical trial Spine 2006; 31: 2875-80.].

PSEUDARTHROSIS

It has been argued that good results following spinal fusion can also be seen in cases of pseudarthrosis in both interbody and postero-lateral fusions [2 Deyo RA, Nachemson A, Mirza SK. Spinal-Fusion surgery – the case for restraint New Eng J Med 2004; 350: 722-6., 43 Frymoyer JW, Hanley EN, Howe J, Kuhlmann D, Matteri RE. A comparison of radiographic findings in fusion and nonfusion patients ten or more years following lumbar disc surgery Spine 1979; 4: 435-0.]. If discogenic pain exists and is of a mechanical nature, it is, however, reasonable to assume that the sensitivity for pain in the discs might differ considerably in different patients. There might be very sensitive discs that react to the slightest movement or compression in the disc region, whereas in other patients the disc might only react after considerably more disc movement or compression. This might be one explanation for why some patients present with very good clinical results despite pseudarthrosis. Another possible explanation is that the pain was not discogenic. The real but unknown reason for the pain might have subsided, leading to apparent success of the fusion without any connection whatsoever to the operation and bony healing.

THE PROBLEM

The problem we must deal with involves, first of all, the selection of those patients who really suffer from segmental pain; secondly we have to find the painful segment(s); and thirdly we have to perform a fusion that best alleviates the pain, with all probability an interbody fusion that does not permit any axial movement [39 Rolander SD. Motion of the lumbar spine with special reference to the stabilizing effect of posterior fusion. An experimental study on autopsy specimens Acta Orthop Scand 1966; (Suppl 90)1-144., 40 Weatherley CR, Prickett CF, O´Brian JP. Discogenic pain persisting despite solid posterior fusion J Bone Joint Surg Br 1986; 68: 142-3.].

Spine surgeons of all kinds have tried to contribute knowledge to this issue but most published studies do not specify the symptomatology of the patients included in the study; it is generally described simply as chronic low back pain with or without nonspecific leg pain. This tells us nothing about whether the pain originates in the sacro-iliac joints, if it is of muscular origin or if it represents segmental pain. The development and use of various internal fixation devices might add some knowledge about how to improve fusion rates [3 Gibson JNA, Waddell G. Surgery for degenerative lumbar spondylosis: Updated Cochrane review Spine 2005; 30: 2312-0., 44 Zdeblick TA. A prospective, randomized study of lumbar fusion Spine 1993; 18: 983-1., 45 Sonntag VKH, Marciano FF. Is fusion indicated for lumbar spinal disorders? Spine 1995; 20: 138S-42S.], but this is only one factor among several. Prospective randomised multicenter studies also encounter the same problem regarding patient selection, perhaps even more so since in these studies a large number of surgeons are responsible for the selection of patients. Of four such studies published recently, three describe the symptoms of the patients included in the study simply as “chronic low back pain” [8 Brox JI, Sörensen R, Friis A. Randomized clinical trial of lumbar instrumented fusion and cognitive intervention and exercises in patients with chronic low back pain and disc degeneration Spine 2003; 28: 1913-21.-10 Brox JI, Reikerås O, Nygaard Ö, et al. Lumbar instrumented fusion compared with cognitive intervention and exercises in patients with chronic back pain after previous surgery for disc herniation: A prospective randomized controlled study Pain 2006; 122: 145-55.] and in the fourth study they are described as “back pain more pronounced than leg pain and no signs of nerve root compression” [7 Fritzell P, Hägg O, Wessberg P, Nordwall A, et al. Volvo award winner in clinical studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain Spine 2001; 26: 2521-34.]. In all four studies the selection of the segment or segments to be fused was based on clinical and radiographic grounds, which we know to be of doubtful value.

ARTIFICIAL DISCS

Some surgeons and clinics advocate the use of artificial discs with the intention of preserving motion of the segment in question [46 Panjabi M, Malcolmson G, Teng E, Tominaga Y, Henderson G, Serhan H. Hybrid testing of lumbar Charité discs versus fusions Spine 2007; 32: 959-66.]. When the artificial disc is placed in the disc space, the outer layers of the annulus are with all probability left in place. These layers contain the nerve endings of the disc innervation [47 Roofe PG. Innervation of annulus fibrosus and posterior longitudinal ligament Arch Neurol Psychiatr 1940; 44: 100-3., 48 Palmgren T, Grönblad M, Virri J, Kääpä E, Karaharju E. An immunohistochemical study of nerve structures in the anulus fibrosus of human normal lumbar intervertebral discs Spine 1999; 24: 2075-9.]. Therefore, if segmental pain is related to movement in the disc space, pain will probably remain following a movement-preserving operation with an artificial disc. The same argument holds true for so-called semi-rigid fixation [49 Grob D, Benini A, Junge A, Mannion AF. Clinical experience with the Dynesys semirigid fixation system for the lumbar spine Spine 2005; 30: 324-1.].

CONCLUSION

In summary, therefore, it is absolutely necessary to find and describe the symptomatology of those patients who might suffer from segmental pain in order to be able to select just those patients for the surgical procedure. Following this selection a number of problems remain: selecting the proper segment for fusion without being able to recognize it visually, choosing a fusion procedure that best alleviates the pain (probably not the postero-lateral procedure), obtaining solid bony healing, and clearly understanding that after having made the right choice in each of these steps we still have a patient in great need of support and rehabilitation after, in most cases, having suffered from severe pain for many years.

CONFLICT OF INTEREST

The author confirms that this article content has no conflict of interest.

ACKNOWLEDGEMENTS

Declared none.

REFERENCES

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[8] Brox JI, Sörensen R, Friis A. Randomized clinical trial of lumbar instrumented fusion and cognitive intervention and exercises in patients with chronic low back pain and disc degeneration Spine 2003; 28: 1913-21.
[9] Fairbank J, Frost H, Wilson-MacDonald J, Yu L M, Barker K, Collins R. Randomised controlled trial to compare surgical stabilisation of the lumbar spine with an intensive rehabilitation programme for patients with chronic low back pain: the MRC spine stabilisation trial Br Med J 2005; 330: 1233-9.
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[11] Eubanks JD, Lee MJ, Cassinelli E, Ahn NU. Prevalence of lumbar facet arthrosis and its relationship to age sex and race Spine 2007; 32: 2058-62.
[12] Kalichman L, Li L, Kim DH, et al. Facet joint osteoarthritis and low back pain in the community-based population Spine 2008; 33: 2560-5.
[13] Vernon-Roberts B, Moore RJ, Fraser RD. The natural history of agerelated disc degeneration The pathology and sequelae of tears Spine 2007; 32: 2797-804.
[14] Macnab I. The traction spur An indicator of segmental instability J Bone Joint Surg Am 1971; 53: 663-70.
[15] Vanharanta H, Sachs BL, Spivey MA, et al. The relationship of pain provocation to lumbar disc deterioration as seen by CT/Discography Spine 1987; 12: 295-8.
[16] Aprill C, Bogduk N. High-intensity zone a diagnostic sign of painful lumbar disc on magnetic resonance imaging Br J Radiol 1992; 65: 361-9.
[17] Braithwaite I, White J, Saifuddin A, Renton P, Taylor BA. Vertebral end-plate (Modic) changes on lumbar spine MRI: correlation with pain reproduction at lumbar discography Eur Spine J 1998; 7: 363-8.
[18] Carragee EJ, Paragioudakis SJ, Khurana S. Volvo award winner in clinical studies. Lumbar high-intensity zone and discography in subjects without low back problems Spine 2000; 25: 2987-92.
[19] Deyo RA, Andersson GBJ, Jarvik JG. Diagnostic test performance: sensitivity, specificity, and predictive value In: Frymoyer JW, Wiesel SW, Eds. The adult and pediatric spine 2004; 15-25. Chapter 2
[20] Hancock MJ, Maher CG, Latimer J, et al. Systematic review of tests to identify the disc SIJ or facet joint as the source of low back pain Eur Spine J 2007; 16: 1539-50.
[21] Spurling RG, Grantham EG. Neurologic picture of herniations of the nucleus pulposus in the lower part of the lumbar region Arch Surg 1940; 40: 375-88.
[22] Kuslich SD, Ulstrom CL, Michael CJ. The tissue origin of low back pain and sciatica A report of pain response to tissue stimulation during operations on the lumbar spine using local anesthesia Orthop Clin North Am 1991; 22: 181-7.
[23] Gill K. Clinical indications for lumbar interbody fusion In: Lin PM, Gill K, Eds. Lumbar interbody fusion Principles and techniques in spine surgery. Rockville, Maryland: Aspen publishers 1989; pp. 35-53. Chapter 4
[24] Burkus JK. Interbody fusion devices: Biomechanics and clinical outcomes In: Vaccaro AR, Betz RR, Zeidman SM, Eds. Priciples and practice of spine surgery. USA: Mosby Inc 2003; pp. 385-97. Chapter 30
[25] Simmons EH, Segil CM. An evaluation of discography in the localization of symptomatic levels in discogenic disease of the spine Clin Orthop Relat Res 1975; 108: 57-69.
[26] Bogduk N, Modic MT. Controversy. Lumbar discography Spine 1996; 21: 402-.
[27] Zdeblick TA. Discogenic back pain In: Rothman RH, Simeone FA, Eds. The Spine. Philadelphia: WB Saunders 1999; pp. 749-65. Chapter 28
[28] Carragee EJ. Is lumbar discography a determinate of discogenic low back pain provocative discography reconsidered Curr Rev Pain 2000; 4: 301-8.
[29] Madan S, Gundanna M, Harley JM, Boeree NR, Sampson M. Does provocative discography screening of discogenic back pain improve surgical outcome? J Spinal Disord Tech 2002; 15: 245-51.
[30] Merskey H, Bogduk N, Eds. Classification of chronic pain Descriptions of chronic pain syndromes and definitions of pain terms. 2nd ed. USA: IASP Press 1994; pp. 175-206.
[31] Holt EP. The question of lumbar discography J Bone Joint Surg 1968; 50A: 720-6.
[32] Carragee EJ, Alamin TF, Carragee JM. Low-pressure positive discography in subjects asymptomatic of significant low back pain illness Spine 2006; 31: 505-9.
[33] Carragee EJ, Tanner CM, Yang B, Brito JL, Truong T. False-positive findings on lumbar discography. Reliability of subjective concordance assessment during provocative disc injection Spine 1999; 24: 2542-7.
[34] Fernström U. A discographical study of ruptured lumbar intervertebral discs Acta Chiru Scand Suppl 1960; ((Suppl 258))1-60.
[35] Carragee EJ, Lincoln T, Parmar VS, Alamin T. A gold standard evaluation of the ”discogenic pain” diagnosis as determined by provocative discography Spine 2006; 31: 2115-3.
[36] Yrjämä M, Vanharanta H. Bony vibration stimulation a new noninvasive method for examining intradiscal pain Eur Spine J 1994; 3: 233-5.
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"Open access will revolutionize 21st century knowledge work and accelerate the diffusion of ideas and evidence that support just in time learning and the evolution of thinking in a number of disciplines."


Daniel Pesut
(Indiana University School of Nursing, USA)

"It is important that students and researchers from all over the world can have easy access to relevant, high-standard and timely scientific information. This is exactly what Open Access Journals provide and this is the reason why I support this endeavor."


Jacques Descotes
(Centre Antipoison-Centre de Pharmacovigilance, France)

"Publishing research articles is the key for future scientific progress. Open Access publishing is therefore of utmost importance for wider dissemination of information, and will help serving the best interest of the scientific community."


Patrice Talaga
(UCB S.A., Belgium)

"Open access journals are a novel concept in the medical literature. They offer accessible information to a wide variety of individuals, including physicians, medical students, clinical investigators, and the general public. They are an outstanding source of medical and scientific information."


Jeffrey M. Weinberg
(St. Luke's-Roosevelt Hospital Center, USA)

"Open access journals are extremely useful for graduate students, investigators and all other interested persons to read important scientific articles and subscribe scientific journals. Indeed, the research articles span a wide range of area and of high quality. This is specially a must for researchers belonging to institutions with limited library facility and funding to subscribe scientific journals."


Debomoy K. Lahiri
(Indiana University School of Medicine, USA)

"Open access journals represent a major break-through in publishing. They provide easy access to the latest research on a wide variety of issues. Relevant and timely articles are made available in a fraction of the time taken by more conventional publishers. Articles are of uniformly high quality and written by the world's leading authorities."


Robert Looney
(Naval Postgraduate School, USA)

"Open access journals have transformed the way scientific data is published and disseminated: particularly, whilst ensuring a high quality standard and transparency in the editorial process, they have increased the access to the scientific literature by those researchers that have limited library support or that are working on small budgets."


Richard Reithinger
(Westat, USA)

"Not only do open access journals greatly improve the access to high quality information for scientists in the developing world, it also provides extra exposure for our papers."


J. Ferwerda
(University of Oxford, UK)

"Open Access 'Chemistry' Journals allow the dissemination of knowledge at your finger tips without paying for the scientific content."


Sean L. Kitson
(Almac Sciences, Northern Ireland)

"In principle, all scientific journals should have open access, as should be science itself. Open access journals are very helpful for students, researchers and the general public including people from institutions which do not have library or cannot afford to subscribe scientific journals. The articles are high standard and cover a wide area."


Hubert Wolterbeek
(Delft University of Technology, The Netherlands)

"The widest possible diffusion of information is critical for the advancement of science. In this perspective, open access journals are instrumental in fostering researches and achievements."


Alessandro Laviano
(Sapienza - University of Rome, Italy)

"Open access journals are very useful for all scientists as they can have quick information in the different fields of science."


Philippe Hernigou
(Paris University, France)

"There are many scientists who can not afford the rather expensive subscriptions to scientific journals. Open access journals offer a good alternative for free access to good quality scientific information."


Fidel Toldrá
(Instituto de Agroquimica y Tecnologia de Alimentos, Spain)

"Open access journals have become a fundamental tool for students, researchers, patients and the general public. Many people from institutions which do not have library or cannot afford to subscribe scientific journals benefit of them on a daily basis. The articles are among the best and cover most scientific areas."


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(University Clinic of Navarre, Spain)

"These journals provide researchers with a platform for rapid, open access scientific communication. The articles are of high quality and broad scope."


Peter Chiba
(University of Vienna, Austria)

"Open access journals are probably one of the most important contributions to promote and diffuse science worldwide."


Jaime Sampaio
(University of Trás-os-Montes e Alto Douro, Portugal)

"Open access journals make up a new and rather revolutionary way to scientific publication. This option opens several quite interesting possibilities to disseminate openly and freely new knowledge and even to facilitate interpersonal communication among scientists."


Eduardo A. Castro
(INIFTA, Argentina)

"Open access journals are freely available online throughout the world, for you to read, download, copy, distribute, and use. The articles published in the open access journals are high quality and cover a wide range of fields."


Kenji Hashimoto
(Chiba University, Japan)

"Open Access journals offer an innovative and efficient way of publication for academics and professionals in a wide range of disciplines. The papers published are of high quality after rigorous peer review and they are Indexed in: major international databases. I read Open Access journals to keep abreast of the recent development in my field of study."


Daniel Shek
(Chinese University of Hong Kong, Hong Kong)

"It is a modern trend for publishers to establish open access journals. Researchers, faculty members, and students will be greatly benefited by the new journals of Bentham Science Publishers Ltd. in this category."


Jih Ru Hwu
(National Central University, Taiwan)


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