The Prevalence of Sacroiliac Joint Degeneration in Asymptomatic Adults

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1 932 COPYRIGHT Ó 2015 BY THE OURNAL OF BONE AND OINT SURGERY, INCORPORATED A commentary by Ronal W. Linsey, MD, is linke to the online version of this article at jbjs.org. The Prevalence of Sacroiliac oint Degeneration in Asymptomatic Aults onathan-ames T. Eno, MD, Christopher R. Boone, MD, Michael. Bellino, MD, an ulius A. Bishop, MD Investigation performe at the Department of Orthopaeic Surgery, Stanfor University School of Meicine, Stanfor, California Backgroun: Degenerative changes of the sacroiliac joint have been implicate as a cause of lower back pain in aults. The purpose of this stuy was to etermine the prevalence of sacroiliac joint egeneration in asymptomatic patients. Methos: Five hunre consecutive pelvic compute tomography (CT) scans, mae at a tertiary-care meical center, of patients with no history of pain in the lower back or pelvic girle were retrospectively reviewe an analyze for egenerative changes of the sacroiliac joint. After exclusion criteria were applie, 373 CT scans (746 sacroiliac joints) were evaluate for egenerative changes. Regression analysis was use to etermine the association between age an the egree of sacroiliac joint egeneration. Results: The prevalence of sacroiliac joint egeneration was 65.1%, with substantial egeneration occurring in 30.5% of asymptomatic subjects. The prevalence steaily increase with age, with 91% of subjects in the ninth ecae of life isplaying egenerative changes. Conclusions: Raiographic evience of sacroiliac joint egeneration is highly prevalent in the asymptomatic population an is associate with age. Caution must be exercise when attributing lower back or pelvic girle pain to sacroiliac joint egeneration seen on imaging. Level of Evience: Prognostic Level IV. See Instructions for Authors for a complete escription of levels of evience. Peer Review: This article was reviewe by the Eitor-in-Chief an one Deputy Eitor, an it unerwent bline review by two or more outsie experts. The Deputy Eitor reviewe each revision of the article, an it unerwent a final review by the Eitor-in-Chief prior to publication. Final corrections an clarifications occurre uring one or more exchanges between the author(s) an copyeitors. Lower back pain has become one of the most commonly encountere ailments in meical practice in general an in orthopaeics in particular 1. It is the most frequent cause of activity limitation for people younger than forty-five years, with a point prevalence of 30%, one-year prevalence of 50%, an lifetime prevalence of 80% 2,3.Itaccountsfor3%ofallemergency-room visits an $30 billion to $50 billion in health-care costs annually 4-6. Sacroiliac joint isease has been implicate as a possible cause of low back pain an ysfunction, an there is increasing interest in invasive treatments ranging from analgesic an corticosteroi injections to percutaneous or open arthroesis 7,8. Traitional open sacroiliac joint arthroesis has been utilize in the past; however, poor clinical results an high complication rates requiring aitional surgery tempere enthusiasm for such proceures 9. Recent avances in surgical technique, incluing minimally invasive sacroiliac joint arthroesis, have le to renewe interest in surgical treatment of low back pain ue to presume sacroiliac joint pathology 10. The iagnosis is typically base on symptoms, physical examination, an egenerative changes seen on compute tomography (CT) scanning. However, the association between pain an egenerative changes on CT scans has not been establishe. It has long been Disclosure: None of the authors receive payments or services, either irectly or inirectly (i.e., via his or her institution), from a thir party in support of any aspect of this work. One or more of the authors, or his or her institution, has ha a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomeical arena that coul be perceive to influence or have the potential to influence what is written in this work. No author has ha any other relationships, or has engage in any other activities, that coul be perceive to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitte by authors are always provie with the online version of the article. Bone oint Surg Am. 2015;97:

2 933 T HE OURNAL OF B ONE &OINT SURGERY BS. ORG THE P REVALENCE OF SACROILIAC OINT D EGENERATION IN scans. We hypothesize that sacroiliac joint egeneration woul be prevalent in asymptomatic iniviuals an that the prevalence woul increase with age. Fig. 1 A type-0 sacroiliac joint has no evience of egenerative changes. known that sacroiliac joint egeneration is common Over thirty years ago, Vogler et al. evaluate forty-five asymptomatic patients with CT scans in an attempt to istinguish raiographic markers of inflammatory sacroiliitis from normal egenerative changes of the sacroiliac joint, fining minor changes such as subchonral sclerosis or joint-space narrowing in up to 83% of patients 11. More avance changes, incluing osteophyte formation (20%), erosions (2%), subchonral cysts (2%), an ankylosis (9%), were seen less commonly 11. More recent research has reveale that raiographic abnormalities elsewhere in the lumbar spine are also highly prevalent in asymptomatic iniviuals. Boen et al. acquire lumbosacral magnetic resonance imaging (MRI) for sixty-seven asymptomatic patients an foun that 28% of the cohort ha substantial pathological changes on MRI, incluing 24% with isc herniation an 4% with spinal stenosis 15. Similarly, ensen et al. evaluate ninety-eight patients with no history of back pain who unerwent lumbosacral MRI an foun that only 36% of the subjects ha no raiographic abnormality, with the remaining 64% showing pathological changes in at least one isc an 38% with multilevel pathological changes 16. All of these stuies foun an increasing prevalence of lumbosacral abnormalities with increasing age an suggest that caution is neee when attributing low back pain to pathological changesseenonavanceimaging. We eneavore to conuct a contemporary stuy similar to that of Vogler et al. but with a larger group of patients of various ages 11. The purpose of the present stuy was to quantify egenerative changes of the sacroiliac joint in a large cohort of asymptomatic patients evaluate with contemporary, high-resolution CT Materials an Methos Institutional review boar approval was obtaine prior to the initiation of the present stuy. Compare with elsewhere in the axial spine where soft-tissue pathology is highly prevalent, sacroiliac joint egenerative changes are primarily osseous in nature, so CT scanning was selecte as the imaging moality of choice Five hunre consecutive scans of the pelvis mae over a twomonth perio for reasons other than low back or pelvic girle pain were ientifie from the picture archiving an communication system (PACS) at an acaemic tertiary-care meical center. Patients were initially exclue if the inication for the CT scan inclue trauma; back, hip, or pelvic pain; or the presence of open physes or any hip or spinal instrumentation. A chart review was also performe, an patients with a history of spinal stenosis; back, pelvic, or hip pain; previous spine, pelvic, or hip surgery; or a history of metastatic, inflammatory, or rheumatologic isease were ientifie an exclue. All CT scans were reviewe by an attening orthopaeic surgeon specializing in pelvic surgery as well as an orthopaeic fellow, an a classification system was applie. Axial plane reformatte images were viewe in the bone winow parameters with manual ajustment by the reviewer as eeme necessary. Sacroiliac joints were evaluate for joint-space narrowing, sclerosis, an osteophyte formation. oints were classifie as type 0 if there were no egenerative changes (Fig. 1); as type 1 if there were mil egenerative changes with minimal osteophyte formation, mil subchonral sclerosis, an/or subtle joint-space narrowing (Fig. 2); as type 2 if there were substantial egenerative changes incluing large osteophytes, substantial subchonral sclerosis, an/or efinite jointspace narrowing without ankylosis (Fig. 3); an as type 3 if there was sacroiliac joint ankylosis (Fig. 4). The prevalence of egenerative changes was quantifie in the overall patient population as well by ecae of life. Statistical analyses in the form of linear regression moels were then run to estimate the change in the os of sacroiliac joint egeneration for each aitional year of age. Fig. 2 A type-1 sacroiliac joint has evience of mil egenerative changes (mil subchonral sclerosis, minimal osteophyte formation, an subtle joint-space narrowing).

3 934 T HE OURNAL OF B ONE &OINT SURGERY BS. ORG THE P REVALENCE OF SACROILIAC OINT D EGENERATION IN Fig. 3 Fig. 4 Fig. 3 A type-2 sacroiliac joint has substantial egeneration without ankylosis (large briging osteophyte formation). Fig. 4 A type-3 sacroiliac joint has sacroiliac joint ankyloses. Source of Funing No external funing was receive for this stuy. Results Atotal of 500 pelvic CTscans were reviewe. Three hunre an seventy-three scans (746 sacroiliac joints) met the inclusion criteria an were use in the stuy. The inication for a CT scan inclue abominal pain in 260 patients (69.7%), cancer staging or surveillance in forty-eight patients (12.9%), evaluation of an abominal or pelvic mass in sixteen patients (4.3%), postoperative complication following abominal surgery in eleven patients (3.0%), an other (preoperative planning, Fig. 5 Patient age istribution.

4 935 T HE OURNAL OF B ONE &OINT SURGERY BS. ORG THE P REVALENCE OF SACROILIAC OINT D EGENERATION IN Fig. 6 Prevalence of sacroiliac (SI) joint egeneration per ecae of life. abominal aortic aneurysm, aortic coarctation, leukocytosis of unknown origin, or ingestion of a foreign object) in thirty-eight patients (10.2%). One hunre an eighty-one patients were male an 192 were female; the mean age was 57.7 years (range, sixteen to ninety-six years) (Fig. 5). The overall prevalence of sacroiliac joint egeneration (type 1, 2, or 3) in at least one sacroiliac joint was 65.1%, an the overall prevalence of substantial egeneration (efine as type 2 or 3) in at least one sacroiliac joint was 30.5%. Degenerative changes were also relate to age (Fig. 6). In patients uner the age of thirty years, only 7.1% showe mil egenerative changes an none ha substantial egenerative changes. In patients who were thirty years an oler, the prevalence of egenerative changes increase progressively with increasing age, with 87.6% of patients sixty years an oler emonstrating some changes an 45% emonstrating substantial egenerative changes. By the ninth ecae of life, 91% of subjects isplaye egenerative changes. A logistic regression moel calculating the increase probability of the presence of sacroiliac joint egeneration reveale a progressive increase of 8.5% (95% confience interval, 6.5% to 10.4%) per year of life in the os of having sacroiliac joint egeneration. A separate logistic regression moel evaluating substantial sacroiliac joint egeneration (type 2 or 3) estimate a 5.5% increase per year of life, peaking at 57.9% in the eighth ecae of life. Discussion We foun a high prevalence of egenerative changes in the sacroiliac joints of asymptomatic aults. Sixty-five percent of the subjects ha some egenerative changes, while 30.5% ha avance egeneration or ankylosis. The prevalence of egenerative changes increase with age, an >85% of asymptomatic patients over the age of sixty ha sacroiliac joint egeneration. Given the high prevalence of pain-free sacroiliac joint egeneration, physicians must be cautious in attributing low back pain to egenerative changes of the sacroiliac joint seen on crosssectional imaging. There are a number of limitations to this stuy. Although we scrutinize patient charts for any evience of back or pelvic pain, it is possible that some patients with sacroiliac joint egeneration actually i have pain that was not reflecte in their meical recor. This coul have le us to overestimate the prevalence of isease in the asymptomatic population. Aitionally, in the absence of a previously valiate classification system, we create our own for the purposes of this stuy, but it requires valiation. Finally, we evaluate an oler patient population an ha only six patients uner the age of twenty. Our finings therefore may not be applicable to a younger patient population. However, our series still captures a large sample of patients with no ocumente history of pelvic or back pain that likely represents a large cross section of the general population. Our results are consistent with those of previous stuies in the orthopaeic literature The present stuy confirme these finings while assessing many more patients across a wier age range using contemporary CT technology. Several stuies have also ocumente the isconnect between pathological finings on imaging an symptoms in other areas of the boy 15,16,19,20.ans et al. evaluate 691 patients with clinical symptoms of sacroiliitis with pelvic MRI an foun that 41% of the patients showe no abnormality on imaging 19. In aition to the previously note

5 936 T HE OURNAL OF B ONE &OINT SURGERY BS. ORG THE P REVALENCE OF SACROILIAC OINT D EGENERATION IN finings in the spine escribe by Boen et al. an ensen et al. 15,16, recent stuies have also ocumente a very high prevalence of asymptomatic trapeziometacarpal arthrosis in patients being seen for a istal raial fracture 20. As has been suggeste with trapeziometacarpal joint egeneration, sacroiliac joint egeneration appears to be a normal part of human aging for which many patients with raiographic finings never seek treatment for pain. These observations an the lack of universally accepte iagnostic criteria may help to explain the ongoing controversy that surrouns the iagnosis an treatment of suspecte sacroiliac joint pain 10. Recent clinical stuies of invasive treatment of the sacroiliac joint have shown mixe results. A systematic review of stuies in which sacroiliac joint arthroesis was compare with enervation as well as analgesic an corticosteroi injection foun clinical improvement in terms of pain regarless of treatment moality 7,21. However, less than half of the patients with available ata on work status were able to return to work, an one of the inclue stuies reveale that 82% of the patients ha marke or severe pain at thirty-nine months after sacroiliac joint arthroesis 9. A better unerstaning of the natural history of sacroiliac joint egeneration provie by our stuy will likely help surgeons to improve their clinical ecision-making. In summary, the prevalence of sacroiliac joint egeneration is high in patients without a history of pain an increases substantially with age. Because sacroiliac joint egeneration may be foun coincientally on imaging stuies mae to investigate the source of back or pelvic pain, physicians must be cautious in attributing pain to these finings an in avocating surgical intervention. n onathan-ames T. Eno, MD Michael. Bellino, MD ulius A. Bishop, MD Stanfor Meicine Outpatient Center, M/C 6342, 450 Broaway Street, Rewoo City, CA aress for.-.t. Eno: jeno@stanfor.eu. aress for M.. Bellino: michael.bellino@stanfor.eu. aress for.a. Bishop: jabishop@stanfor.eu Christopher R. Boone, MD Bellevue Bone an oint Physicians, th Avenue N.E., Bellevue, WA aress: boone34@gmail.com References 1. Frymoyer W. Back pain an sciatica. N Engl Me Feb 4;318(5): Kent PM, Keating L. The epiemiology of low back pain in primary care. Chiropr Osteopat ul 26;13:13. Epub 2005 ul Dagenais S, Haleman S. Evience-base management of low back pain. St. Louis: Elsevier Mosby; Waterman BR, Belmont P r, Schoenfel A. 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