Pain Medicine 2011; 12: 565 570 Wiley Periodicals, Inc. SPINE SECTION Original Research Articles Sacroiliac Joint Pain after Lumbar and Lumbosacral Fusion: Findings Using Dual Sacroiliac Joint Blockspme_1087 565..570 Po-Chou Liliang, MD, Kang Lu, MD, PhD, Cheng-Loong Liang, MD, Yu-Duan Tsai, MD, Kuo-Wei Wang, MD, and Han-Jung Chen, MD, PhD Department of Neurosurgery, E-Da Hospital/I-Shou University, Kaohsiung, Taiwan Reprint requests to: Po-Chou Liliang, MD, Department of Neurosurgery, E-Da Hospital/ I-Shou University, No. 1, Yi-Da Road, Jiau-Shu Tsuen, Yan-Chau Shiang, Kaohsiung County 824, Taiwan. Tel: +886-7-6150011; Fax: +886-7-6150982; E-mail: ed100172@edah.org.tw. Abstract Objective. The present study was performed to ascertain whether sacroiliac joint (SIJ) pain represents a potential source of pain in patients who have undergone lumbar or lumbosacral fusions. Design. Prospective cohort study. Patients and Methods. Between June 2007 and June 2009, 130 patients who underwent lumbar or lumbosacral fusions were evaluated for SIJ pain. Fifty-two patients for whom positive findings were obtained on at least three of the provocating tests for SIJ pain were selected to receive dual diagnostic blocks. Outcome Measures. A positive response was defined as characteristic pain reduction of 75% for 1 4 hours following the SIJ blocks. Predictive factors for a positive response to the SIJ blocks were also investigated. Results. Among the 52 patients, 21 were considered to have SIJ pain on the basis of two positive responses to diagnostic blocks. Univariate analysis revealed that the predictive factors related to positive responses were unilateral pain (P = 0.002), more than three positive responses to provocating maneuvers (P = 0.02), and postoperative pain with characteristics different from those of preoperative pain (P = 0.04). Conclusions. SIJ pain is a potential source of pain after lumbar and lumbosacral fusion surgeries. Provocating SIJ maneuvers represent reliable tests for SIJ pain. The characteristics of postoperative SIJ pain frequently differ from those of preoperative pain. Key Words. Lumbar Fusion; Lumbosacral Fusion; Postoperative Back Pain; Sacroiliac Joint Blocks; Sacroiliac Joint Pain Introduction Findings of a multicenter study [1] strongly support the concept that lumbar fusion surgery results in greater pain relief than conservative treatment for patients with chronic low back pain. Nonetheless, failure rates associated with lumbar fusion surgeries range from 5% to 30% despite careful selection of patients [2,3]. Low back pain following lumbar fusion has been attributed to many different causes. Several investigators have invoked the involvement of the sacroiliac joint (SIJ) in the postoperative pain experienced by patients who have undergone lumbar fusion surgeries [3 6]. However, the frequency and characteristics of SIJ pain after lumbar and lumbosacral fusions remain to be determined. Furthermore, controversy currently exists regarding the optimal method for diagnosis of SIJ pain. Although SIJ pain may be identified by a single SIJ block [3,4], the false-positive rate using a single block is reported to be as high as 20% [7]. The present study was performed to ascertain whether SIJ represents a potential pain source for patients who have undergone lumbar fusion surgeries. Dual rather than single SIJ blocks were employed to establish the presence of SIJ pain. In addition, the predictive factors for SIJ pain after lumbar fusions were identified. Methods Design and Setting This prospective cohort study was approved by the institutional review board of our hospital. Between June 2007 565
Liliang et al. and June 2009, 130 patients who underwent lumbar or lumbosacral fusions were evaluated in our spine center for persistent chronic (no less than 3 months) back pain after prior surgery. There were 397 lumbar/lumbosacral fusions performed in our institute during this period. However, some patients were referred from other institutes. Inclusion Criteria Patients were included if their reported pain was below the L5, over the posterior aspect of one or both SIJs, with or without leg pain, and with a distribution compatible with an SIJ origin [8]. All patients received medical history taking, image studies, and physical examinations. Patients who exhibited positive findings on at least three of the following provocating tests were included[9]: pain upon application of pressure to the sacroiliac ligaments, Patrick s test, Gaenslen s test, Shear test, Yeoman maneuver, and standing extension test. All patients with pain meeting inclusion criteria were selected to receive diagnostic blocks for SIJ pain. Exclusion Criteria Patients with pain located midline or with symmetrical pain above the level of L5, with clear nerve root compression signs (motor or sensory deficits), of age less than 18 years, with spinal tumors, with systemic infections, with recent fractures in the lumbar spine region, with proven osteoarthritis of the hip with clinical symptoms, with pain related to disc or facet joint origins, who were pregnant, with coagulopathy, or who had a history of allergies to injected medications were excluded. Patients with signs of sacroiliitis (ankylosing spondylitis, reactive arthritis, psoriatic arthritis, or enteropathic arthritis) were also excluded. Diagnostic Evaluation Dual SIJ blocks were performed for the diagnosis of SIJ pain. Each patient underwent two diagnostic SIJ blocks on separate occasions. Patients with two consecutive positive responses were considered to have SIJ pain. A positive response was defined as characteristic pain reduction of 75% or greater for 1 4 hours following the SIJ block. The blocks were capable of stopping pain at the characteristic site but were unable to block all pain (such as pain above the L5, pain at the lateral aspect of the thigh, abdominal pain, and lower leg pain). Patients with one positive and one negative response received a third SIJ block to eliminate the false-positive or false-negative finding. Patients who did not experience adequate pain relief during the 1 4 hours following performance of the SIJ blocks were considered not to have SIJ pain. Responses to SIJ blocks were independently evaluated by a nurse who was not involved in the procedure. SIJ Block Procedures Informed consent was obtained from each patient prior to performing the SIJ blocks. Standard procedures, which are described elsewhere [10], were selected to perform the blocks. The patient was placed in the prone position, and the sacroiliac skin was prepared and draped. With the C-arm tube perpendicular to the table, the skin over the inferior margin of the SIJ was marked. The tube was adjusted slightly as necessary until the entrance to the SIJ was clearly visible. A 23-gauge 3.5-inch spinal needle was then inserted into the entrance. Confirmation of the correct needle position was made with 0.5 ml nonionic contrast medium injection. Then, 1 ml of 0.5% bupivacaine (or 2% lidocaine) mixed with 1 ml (40 mg) of triamcinolone acetonide (Kenalog 40; Bristol-Myer Squibb, NJ) was injected into the SIJ. Predictive Factors for SIJ Pain The following were examined for the capacity to serve as predictive factors for a positive response to SIJ blocks: age, gender, pain location (unilateral or bilateral), body mass index (BMI), findings from provocating maneuvers, fusion levels and lumbosacral fusion, pain with characteristics different from those of preoperative pain, pain-free intervals, and bone graft harvesting on the painful side. Statistical Analysis Data were subjected to univariate analysis using the independent samples Student s t-test, c 2 test, or Fisher s exact test as appropriate. Findings were considered statistically significant if P values were less than 0.05. Data were analyzed using the SPSS 12.0 (SPSS Inc., Chicago, IL) software package. Results Patient Findings Fifty-two patients had pain that met the inclusion criteria. Figure 1 shows the results of the dual diagnostic SIJ blocks. Twenty-six patients had two consecutive negative responses and were therefore considered not to have SIJ pain. Seventeen patients with two positive responses to diagnostic blocks were judged to have SIJ pain. Nine patients exhibited inconsistent responses and received a third diagnostic block; of these, four had a positive response to the third block. Among the 52 patients, 21 were considered to have SIJ pain. Demographic data for the 52 patients (38 women and 14 men) with presumptive SIJ pain are presented in Table 1. Their mean age was 63.0 11.5 years (range, 38 86 years). Their mean BMI was 25.5 3.2 (range, 21 35). Twenty-eight patients had bilateral low back pain whereas 24 had unilateral pain (nine with left-sided and 15 with right-sided pain). Twenty patients underwent lumbar fusion to sacrum. Twenty-one received lumbar fusion at one spinal level, 21 had fusion at two levels, and 10 had fusion at more than two levels with instrumentation. Ten patients received posterior iliac crest bone graft harvesting, and six of these had ipsilateral post-fusion pain. Other patients received bone grafts from another origin (spinal processes, lamina, or allograft). 566
Sacroiliac Joint Pain after Lumbar Fusion 52 patients who had pain meeting the inclusion criteria were selected for diagnostic blocks Figure 1 Flow diagram illustrating the results of diagnostic SIJ blocks. Of 52 patients who met the inclusion criteria, 21 were considered to have SIJ pain. False-Positive and False-Negative Responses If the patients did not have third SIJ blocks, the falsepositive rate was 26.0% (95% confidence interval [CI] 11.1% ~ 48.6%) and the false-negative rate was 10.3% (95% CI 2.7% ~ 28.5%) according second SIJ blocks. False-positive and false-negative responses were eliminated by performance of a third SIJ block. Those patients that had two positive results were included in the SIJ pain group. Predictive Factors 26 patients had two consecutive negative response (not SIJ pain) Table 1 General characteristics of 52 low back pain patients after lumbar fusion Characteristics Number (%) or mean SD (range) Age, year 63.0 11.5 (38 86) Gender Male/female (%) 14 (27)/38 (73) Body mass index 25.5 3.2 (21 35) Location Left (%) 9 (17.3) Right (%) 15 (28.8) Bilateral (%) 28 (53.9) Lumbar fusion levels Lumbosacral fused 20 (38.5) One level fused 21 (40.4) Two levels fused 21 (40.4) More than two levels fused 10 (19.2) Sacroiliac joint blocks positive 21 (40.4) Five had negative response (not SIJ pain) Univariate analysis revealed that the predictive factors related to positive responses to the SIJ blocks were unilateral pain (P = 0.002), positive responses to four or more provocating maneuvers (P = 0.02), and pain of character different from that of preoperative pain (P = 0.04). However, age, gender, BMI, L5 S1 fusion, fusion level (single or multiple levels), pain-free intervals, and iliac crest bone graft harvesting on the painful side were not significantly associated with positive responses to the SIJ blocks (Table 2). Complications Four (7.7%) patients experienced transient weakness of the lower extremities (mostly due to ventral side injection material leakage) persisting less than 8 hours after performance of the SIJ blocks. Discussion 9 patients had one negative and one positive response These patients underwent third SIJ block Four had positive response (SIJ pain) 17 patients had two consecutive positive response (SIJ pain) Findings of the present study reveal that SIJ pain is a potential source of pain after lumbar fusion surgeries and that provocating SIJ maneuvers represent reliable tests for the presence of SIJ pain following such surgeries. Furthermore, univariate analysis for the predictive factors related to positive responses to SIJ blocks revealed that unilateral pain, positive responses to more than three provocating SIJ maneuvers, and pain with characteristics different from those of preoperative pain each increase the possibility of SIJ pain after lumbar fusion. The SIJ is a common site of low back pain [11] and may potentially be involved in such pain after lumbar or lumbosacral fusion surgeries [3 6]. Maigne and Planchon [3] reported that the SIJ plays a role in pain persisting after lumbar fusion, and Katz and colleagues [4] reported that the SIJ was responsible for generation of pain in certain patients who underwent lumbosacral fusions. However, in each of these studies, SIJ pain was diagnosed using a single block, an approach associated with significant 567
Liliang et al. Table 2 Predictive factors in sacroiliac joint pain (N = 52) Variables SIJ pain (N = 21) Not SIJ pain (N = 31) P value Age 60.3 9.2 64.9 12.6 0.154 Gender 0.118 Male (N = 15) 9 6 Female (N = 24) 17 7 Unilateral or bilateral 0.002 Left (N = 9) 6 3 Right (N = 15) 10 5 Bilateral (N = 28) 5 23 Body mean index 25.6 3.8 25.5 2.9 0.11 Provocating maneuvers 0.02 Three maneuvers positive 6 19 More than three maneuvers positive 15 12 Lumbosacral fused 7 (33) 13 (42) 0.532 Lumbar spine fused levels 0.765 One level fused 9 12 2 levels fused 12 19 Different from preoperative pain 14 (67) 11 (35) 0.04 Free interval 3 months 15 (71) 21 (68) 0.392 Bone graft harvesting on the painful side 2 (11) 4 (13) 0.91 SIJ = sacroiliac joint. false-positive rates [9]. In the present study, the patients with persistent low back pain after lumbar fusion were selected to receive provocating SIJ maneuvers. Those with positive results on at least three of the SIJ provocating tests were then selected for SIJ blocks. The presence of pain from SIJ was confirmed using dual SIJ blocks, and the SIJ was shown to be a likely source of pain in 40% of the cases. Pain from SIJ was found to present unilaterally more frequently (76%) than bilaterally (24%). The incidence of SIJ pain when three or more positive responses of six provocating SIJ maneuvers is 40% in our study; it is lower than others [9] who use the same methods for patient selection, which resulted in an incidence of 60%. Another study [12] used five provocating tests (distraction test, compression test, thigh trust test, Patrick sign, Gaenslen s test) for evaluation, and the predictive rate was high if three provocating maneuvers were positive. Patients, provocating maneuvers, study methods, and performers are different. More investigations are needed to clarify this issue. In the present study, the incidence of SIJ pain for patients exhibiting only three positive responses of six provocating SIJ maneuvers was 24%. When patients had four or more positive responses of six provocating SIJ maneuvers, the incidence of SIJ pain was higher (56%; P = 0.02). From the findings of the present study and those of others [9,12], it is concluded that use of multiple regimen provocating SIJ maneuvers represents a reliable tests for the presence of SIJ pain. Current indications for lumbar fusion include low back pain with spinal instability, spondylolisthesis, and spinal stenosis [13]. Characteristics and symptoms of such low back pain differ from those of SIJ pain. In the present study, 67% of patients diagnosed with SIJ pain had pain with characteristics different from those of their preoperative pain, and this difference in characteristics was identified as a significant predictive factor for positive diagnostic blocks of SIJ pain. These findings agree with those of Maigne and Planchon [3], who reported that the only criterion characterizing patients with SIJ pain following lumbar fusion was postoperative pain that differed from preoperative pain in its distribution. Several hypotheses have advanced to explain the causes of SIJ pain in patients who have undergone lumbar fusion [3,4,14,15]. These hypotheses include postsurgical transfer of a mechanical load on the SIJ, disruption of the SIJ following bone graft harvesting, and inappropriate lumbar fusion due to misdiagnosis of SIJ pain as a cause of pre-fusion low back pain. A mechanical load may potentially be transferred on the SIJ as a consequence of straightening of the fused lumbar segments [3,4]. This straightening process increases load transfer on the disc above the fused level [16], and the disc below the fused level is also subjected to new strains [17] due to a translational motion [18]. Some investigators have observed that SIJ blocks are more often positive in patients with lumbosacral fusion [3,4]. In the present study, however, no differences in responses were observed between the patients with or without lumbosacral fusion surgeries. Further study is required to resolve these apparently contradictory findings. Regarding disruption of the SIJ following bone graft harvesting, Ebraheim et al. [15] observed a high frequency of a sacroiliac inner table disruption resulting in sacroiliac pain in subjects with donor site pain. In 568
88% of the patients in the present study, however, bone graft was harvested from the lamina or spinal processes; only six patients underwent bone graft harvesting from the iliac crest. As SIJ pain was present with a similar frequency in patients with or without bone graft harvesting from the iliac crest, disruption of the SIJ due to bone graft harvesting does not explain the presence of SIJ pain in the subjects in the present study. Misdiagnosis of SIJ pain as a pre-fusion low back pain also appears to be a possible explanation for post-fusion SIJ pain because absence of a post-fusion interval free of pain and post-fusion pain similar to preoperative pain would be expected in such cases. It is possible that SIJ pain may develop in certain patients independently of lumbar diseases and in a manner not associated with lumbar fusion surgery. Although a clear predisposition to SIJ dysfunction has not been identified, several factors such as degenerative joint disease, SIJ laxity, and trauma have been implicated in the etiology of SIJ dysfunction [19,20]. Further investigation is needed to confirm this possibility. Lack of a diagnostic gold standard for SIJ pain [10] is an important limitation of the present study. Double SIJ blocks and controlled comparative blocks have been described as the gold standards; however, false-positive and false-negative findings are possible using these blocks [21]. We performed 397 lumbar/lumbosacral fusions during this period. However, some patients were referred from other institutes. Some patients were selfreferral. It is difficult to know the total number of fusion operations performed in other institutes, and then it might not be easy to estimate the incidence of SIJ pain following fusion. This is another limitation. Conclusion Because low back pain can arise from a variety of causes after lumbar fusion has been performed, diagnosis by history taking, physical examinations, and image studies is difficult [22]. Based on the findings of the present report, painful SIJ should be considered as a potential source of such postsurgical low back pain. Provocating SIJ maneuvers serve as reliable tests for SIJ pain, which often presents with characteristics different from those of preoperative pain. Diagnostic SIJ blocks are currently the most reliable diagnostic approaches for identification of patients with SIJ pain following lumbar fusion surgery. References 1 Fritzell P, Hagg O, Wessberg P, et al. Lumbar fusion vs nonsurgical treatment for chronic low back pain: A multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine 2001;26: 2521 32. 2 Bose B. Outcomes after posterolateral lumbar fusion with instrumentation in patients treated with adjunctive Sacroiliac Joint Pain after Lumbar Fusion pulsed electromagnetic field stimulation. Adv Ther 2001;18:12 20. 3 Maigne JY, Planchon CA. Sacroiliac joint pain after lumbar fusion. A study with anesthetic blocks. Eur Spine J 2005;14:654 8. 4 Katz V, Schofferman J, Reynolds J. The sacroiliac joint: A potential cause of pain after lumbar fusion to the sacrum. J Spinal Disord Tech 2003;16:96 9. 5 Slipman CW, Shin CH, Patel RK, et al. Etiologies of failed back surgery syndrome. Pain Med 2002;3:200 14. 6 Liliang PC, Lu K, Weng HC, et al. The therapeutic efficacy of sacroiliac joint blocks with triamcinolone acetonide in the treatment of sacroiliac joint dysfunction without spondyloarthropathy. Spine 2009;34: 896 900. 7 Maigne JY, Aivakiklis A, Pfefer F. Results of sacroiliac joint double block and value of sacroiliac pain provocation test in 54 patients with low back pain. Spine 1996;21:1889 92. 8 van der Wurff P, Buijs EJ, Groen GJ. Intensity mapping of pain referral areas in sacroiliac joint pain patients. J Manipulative Physiol Ther 2006;29:190 5. 9 Slipman CW, Sterenfeld EB, Chou LH, et al. The predictive value of provocative sacroiliac joint stress maneuvers in the diagnosis of sacroiliac joint syndrome. Arch Phys Med Rehabil 1998;79:288 92. 10 Bogduk N (ed). Sacroiliac Joint Blocks, Practice Guidelines for Spinal Diagnostic and Treatment Procedures. San Francisco, CA: International Spine Intervention Society; 2004:66 86. 11 Slipman CW, Jackson HB, Lipetz JS, et al. Sacroiliac joint pain referral zones. Arch Phys Med Rehabil 2000;81:334 8. 12 van der Wurff P, Buijs EJ, Groen GJ. A multitest regimen of pain provocation tests as an aid to reduce unnecessary minimally invasive sacroiliac joint procedures. Arch Phys Med Rehabil 2006;87:10 4. 13 Weinstein JN, Lurie JD, Tosteson TD, et al. Surgical vs nonsurgical treatment for lumbar degenerative spondylolisthesis. N Engl J Med 2007;356:2257 70. 14 Frymoyer JW, Howe J, Kuhlman D. The long-term effects of spinal fusion on the sacroiliac joints and ilium. Clin Orthop 1978;134:196 201. 15 Ebraheim NA, Elgafy H, Semaan HB. Computed tomographic findings in patients with persistent sacroiliac pain after posterior iliac graft harvesting. Spine 2000;25:2047 51. 569
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