A Commentary on Appropriate Use Criteria for Sacroiliac Pain

Pain Medicine 2017; 18: 2055–2057 doi: 10.1093/pm/pnx234 PERSPECTIVE & COMMENTARY Commentary A Commentary on Appropriate Use Criteria for Sacroiliac Pain evaluated for accuracy only in normal volunteers [1,3]. No one has reported applying these tests in a sample of natural patients. We do not know if posterior ligament pain is common, rare, or nonexistent. We do not know the extent to which it occurs in isolation or in combination with sacroiliac joint pain. In terms of scientific attention, the oldest entity is sacroiliac joint pain. The concept is that the pain arises within the sacroiliac joint itself. The diagnostic test for this condition is controlled, intra-articular local anesthetic blocks of the sacroiliac joint. Relief of pain following such blocks implies that the source of pain lies in structures that are bathed by or infiltrated by the local anesthetic, such as the capsule of the joint. The panellists for the AUC, published by MacVicar et al. [4], advocate physical examination as a screening test before considering diagnostic blocks. There is merit in this, but only in certain respects. Positive responses to three or more provocation tests have a positive likelihood ratio of 3.7 [5] and a negative likelihood ratio of 0.20 (i.e., the reciprocal of 5.0). The positive likelihood ratio is not particularly helpful clinically because the resultant diagnostic confidence (post-test probability) is only 50%, meaning that only 50% of patients who are positive to physical examination will prove to be positive to diagnostic blocks. This figure is low because the false-positive rate of physical examination is high (24%). The negative likelihood ratio, however, is more useful. If the prevalence of sacroiliac joint pain is, say, 20%, physical examination eliminates 64 of every 100 potential patients from undergoing diagnostic blocks, which constitutes an efficiency of practice; because the false-negative rate of physical examination is low (15%), the clinical cost of this efficiency is only three patients who might have sacroiliac joint pain being denied diagnostic blocks. The second entity is pain stemming from the interosseous or dorsal sacroiliac ligaments, which lie behind the sacroiliac joint and which would not be anesthetised by an intra-articular local anesthetic block. The diagnostic test for this entity would be controlled, diagnostic blocks of the lateral branches of the sacral dorsal rami (S1 to S4), branches of which innervate the posterior ligaments. In this regard, it has been demonstrated that lateral branch blocks do not protect normal volunteers from experimental sacroiliac joint pain [1]. Lateral branch blocks relieve pain from the posterior ligaments; they cannot block pain from the sacroiliac joint. Intra-articular blocks relieve joint pain; they do not relieve ligament pain. Consequently, intra-articular blocks cannot be diagnostic of posterior ligament pain, nor can lateral branch blocks be diagnostic of sacroiliac joint pain. The prevalence of each of the two entities is important because it underlies the possible false-positive and false-negative rates of diagnostic tests, be they physical examination or diagnostic blocks. In this regard, several studies have estimated the prevalence of sacroiliac joint pain as between 10% and 33% among patients presenting with chronic low back pain [2]. With potentially one in five patients having this condition, its diagnosis is worth pursuing. In contrast, however, we have no data on the prevalence of posterior sacroiliac ligament pain. Diagnostic tests for this entity have been developed and However, provocation tests have been validated only for sacroiliac joint pain. No studies have tested physical examination for the diagnosis of posterior ligament pain. Consequently, although physical examination might constitute an efficiency for the pursuit of sacroiliac joint pain, its value is totally unknown for the pursuit of posterior ligament pain. There is no published evidence that justifies using physical examination either to direct or to deny lateral branch blocks for the pursuit of posterior ligament pain. The AUC also provides recommendations pertaining to injections into the sacroiliac joint [4]. It highlights that, in many jurisdictions, physicians are reimbursed for only a single injection. Therefore, they perform a pragmatic procedure combining a diagnostic agent and a therapeutic agent and argue that temporary relief constitutes a positive diagnostic block and that prolonged relief C 2017 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: [email protected] V 2055 Downloaded from https://academic.oup.com/painmedicine/article/18/11/2055/4569658 by guest on 25 May 2022 Fundamental to any assessment of an appropriate use criterion (AUC) for sacroiliac pain is the recognition that there are at least two entities in question. The two are distinctly different conceptually; each requires a different paradigm of diagnosis and treatment, and the evidence base for each differs both in quality and quantity. Bogduk A diagnosis of sacroiliac joint pain cannot be established or inferred from a single intra-articular block. Some form of controlled block would be required in order to make the diagnosis. If for no other reasons, a diagnostic block should be repeated in order to identify patients who fail to respond to a second block. Experience with other spinal conditions has documented that some 30% of patients fail to respond to a repeat block [8], revealing a lack of consistency of response. Although a positive response to a single block might be satisfying to the physician as well as the patient, unless controlled blocks are used to exclude false-positive responses, physicians have no legitimate claim of a diagnosis. The AUC recommends a repeat injection if the first injection (of local anesthetic and steroid) provides at least 75% relief of pain for the duration of action of the local anesthetic used. The purpose of this action is either ambiguous or elusive. If the purpose of the repeat injection is to confirm the diagnosis, the steroid is redundant, for only a local anesthetic is required to anesthetize the joint. Meanwhile, by having a short-lasting response, the patient has already shown that the first injection was not therapeutic, whereupon the further use of steroids as a therapeutic agent is neither indicated nor justified. Under these conditions, the routine use of a second injection of steroids cannot be distinguished from hopeful behavior: repeating an injection just in case it might work better on the second occasion. The preoccupation with using steroids seems to be based on a misplaced faith in steroids as a therapeutic agent. The published evidence does not justify this faith. The reputation of intra-articular steroids for sacroiliac joint pain rests on descriptive studies, of various degrees of quality, that report various degrees of success for short or longer periods [9,10]. The best quality outcome study happens to have followed the protocols advocated by the AUC. It investigated 150 patients with presumptive sacroiliac joint pain based on clinical examination [11]. All underwent a first intra-articular injection of bupivacaine and triamcinolone, from which 88 had at least 75% pain relief. Of these 88, 58 underwent a second injection of the same agents, from which 39 had relief again. Of these 39 patients, 13 had at least 50% relief that lasted 2056 less than six weeks, but 26 (45%) had relief that lasted longer than six weeks (36.8 6 9.9 weeks). Some physicians might argue that, although modest, this success rate is worth pursuing, for no other conservative therapy rivals achieving 50% relief in 45% of patients. However, no controlled study has vindicated intra-articular steroids as a treatment for mechanical sacroiliac joint pain. No studies have shown that intra-articular steroids reduce the burden of illness or succeed in restoring patients to normal life with no need for other health care. At best, therefore, the available evidence shows that intra-articular steroids might be palliative to some extent, in a small proportion of patients, for some unpredictable duration. The AUC maintains that lateral branch blocks would be appropriate in patients who had a positive response to an initial intra-articular injection of local anesthetic and steroid. Seemingly, the panelists of the AUC considered the two blocks to be complementary: that having diagnosed sacroiliac joint pain with the first block, the next step could be to perform lateral branch blocks because lateral branch radiofrequency neurotomy could be used to treat the joint pain. While the reasoning may be that lateral branch blocks may reduce the intensity of sacroiliac joint pain by blocking the posterior innervation of the joint, the degree to which lateral branch blocks might relieve pain in patients with proven sacroiliac joint pain is unknown and has not been studied. Meanwhile, the cardinal indication for lateral branch blocks would be suspicion of posterior ligament pain. The investigation of that entity is neither pursuant to nor dependent on a diagnosis of sacroiliac joint pain. Confusion deepens when the indications for lateral branch neurotomy are consulted. The panelists agreed that neurotomy was appropriate if lateral branch blocks provided 100% relief and if sacroiliac joint blocks provided greater than 50% relief, but neurotomy was not appropriate if sacroiliac joint blocks provided less than 50% relief despite lateral branch blocks providing 100% relief. Implicitly, the panelists attributed great stock to the response to injections into the sacroiliac joint. It seems that they did not recognize that patients could have posterior ligament pain without sacroiliac joint pain. Those patients would have complete relief of pain from lateral branch blocks, but their response to sacroiliac joint blocks is spurious and irrelevant. On behalf of patients and responsible practitioners, it is disturbing if physicians are restricted, by those who pay, to single injections. That restriction prevents good practice based on science, which relies on controlled diagnostic blocks. Single injections do not provide valid information; they create only diagnostic noise. However, restrictions to practice are not a matter of science; they are a socio-economic matter, about which others might care to comment. On the other hand, it is disturbing that the AUC contains some recommendations made without applying the Downloaded from https://academic.oup.com/painmedicine/article/18/11/2055/4569658 by guest on 25 May 2022 constitutes a positive therapeutic response. However, there is no evidence that temporary relief can validly be attributed to only the local anesthetic. Nor is there evidence that a prolonged response is specifically due to the therapeutic agent. There is contrary evidence, from studies of other sources of spine pain, that intraarticular injections of local anesthetic alone can provide long-lasting relief of pain [6], and there is evidence from animal studies that steroid preparations have a local anesthetic effect [7]. Moreover, it is axiomatic philosophically that without appropriate controls a physician cannot tell if a positive response, of any duration, to a single, combined injection is a placebo response to the local anesthetic, or to the steroid, or to both. To believe otherwise may amount to no more than wishful thinking. Commentary basic science literature or the known anatomic considerations of the posterior pelvis. Instead, they appeared to be made based on the current clinical outcome studies and practice patterns agreed upon by expert consensus. Rather than entrench current practices, it would have been more noble if the AUC defined appropriate practices based on evidence and responsible clinical reasoning—and if these were not compatible with existing payment systems, then to argue for reform so that patients could get proper care and physicians could be reimbursed for honestly providing that care. References 1 Dreyfuss P, Henning T, Malladi N, Goldstein B, Bogduk N. The ability of multi-site, multi-depth sacral lateral branch blocks to anesthetize the sacroiliac joint complex. Pain Med 2009;10:679–88. 2 Kennedy DJ, Engel A, Kreiner S, et al. Fluoroscopically guided diagnostic and therapeutic intra-articular sacroiliac joint injections: A systematic review. Pain Med 2015;16:1500–18. 3 Dreyfuss P, Snyder BD, Park K, et al. The ability of single site, single depth sacral lateral branch blocks to anesthetize the sacroiliac joint complex. Pain Med 2008;9:844–50. 4 MacVicar J, Kreiner D, Duszynski B, Kennedy D. Appropriate use criteria for fluoroscopically-guided diagnostic and therapeutic sacroiliac interventions: Results from the Spine Intervention Society-convened collaborative. Pain Med 2017;18: 5 Szadek KM, van der Wurff P, van Tulder MW, Zuurmond WW, Perez RSGM. Diagnostic validity of criteria for sacroiliac joint pain: A systematic review. J Pain 2009;10:354–68. 6 Barnsley L, Lord SM, Wallis BJ, Bogduk N. Lack of effect of intraarticular corticosteroids for chronic pain in the cervical zygapophyseal joints. N Engl J Med 1994;330:1047–50. 7 Johansson A, Hao J, Sjolund B. Local corticosteroid application blocks transmission in normal nociceptive C-fibres. Acta Anaesthesiol Scand 1990;34: 335–8. 8 Lord SM, Barnsley L, Bogduk N. The utility of comparative local anaesthetic blocks versus placebo-controlled blocks for the diagnosis of cervical zygapophysial joint pain. Clin J Pain 1995;11:208–13. 9 Hawkins J, Schofferman J. Serial therapeutic sacroiliac joint injections: A practice audit. Pain Med 2009;10:850–3. is J, et al. Injection of 10 Hart R, Wendshce P, Koc anaesthetic-corticosteroid to relieve sacroiliac joint pain after lumbar stabilisation. Acta Chir Orthop Traimatol Cech 2011;78:339–42. 11 Liliang PC, Lu K, Weng HC, et al. The therapeutic efficacy of sacroiliac joint blocks with trimacinolone acetonide in the treatment of sacroiliac joint dysfunction without spondyloarthropathy. Spine 2009; 34:896–900. 2057 Downloaded from https://academic.oup.com/painmedicine/article/18/11/2055/4569658 by guest on 25 May 2022 NIKOLAI BOGDUK, MD, Phd, DSc The University of Newcastle, Newcastle, Australia multispecialty 2081–95.