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Research Review By Dr. Jeff Muir©

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Date Posted:

August 2015

Study Title:

The prevalence of sacroiliac joint degeneration in asymptomatic adults

Authors:

Eno JJT, Boone CR, Bellino MJ, Bishop JA

Author's Affiliations:

Department of Orthopaedic Surgery, Stanford University School of Medicine, California, USA.

Publication Information:

Journal of Bone & Joint Surgery (Am) 2015; 97: 932-6.

Background Information:

Low back pain is one of the most commonly encountered ailments in general and musculoskeletal practice, with the sacroiliac (SI) joint often implicated as a cause of, or contributor to, mechanical low back pain (1, 2). Degeneration of the SI joint is often identified as a causative agent in SI joint-related low back pain (3-6); however, the role of degeneration in SI joint pain etiology remains controversial. Vogler (3) completed the early work on the link between SI joint degeneration and low back pain, noting that minor changes were observed in up to 83% of LBP patients on imaging.

In this study, the authors sought to expand upon the work of Vogler by increasing the size and age range of the cohort and by utilizing contemporary, high-resolution CT scanning to investigate the role of SI joint degeneration in mechanical low back pain.

Pertinent Results:

Study Population:
500 pelvic CT scans were reviewed, with 373 (746 SI joints) deemed eligible for inclusion. Indications for CT scanning included abdominal pain (n = 260), cancer staging (n = 48), abdominal or pelvic mass (n = 16), postoperative complications (n = 11) and other (n = 38). Mean age of patients was 57.7 years (range: 16-90); 181 patients were male.

Primary Outcomes:
  • SI joint degeneration of any grade (1, 2 or 3) in one SI joint was present in 65.1% of patients; substantial degeneration was present in at least one joint in 30.5% of patients.
  • Degenerative changes were related to age. Degeneration was present in patients under 30 in only 7.1% of cases. In those 30 yrs and older, degeneration increased progressively with age, with 87.6% of patients over 60 demonstrating degenerative changes (45% demonstrated substantial changes). Over age 80, 91% of patients displayed degenerative changes.
  • Logistic regression analysis revealed a progressive increase of 8.5% per year of life regarding the odds of having SI joint degeneration. A second logistic regression model evaluated substantial sacroiliac joint degeneration (type 2 or 3) and estimated a 5.5% increase per year of life, peaking at 57.9% in the eighth decade of life.

Clinical Application & Conclusions:

The authors’ findings, which support those of Vogler, indicate that the prevalence of SI joint degeneration in asymptomatic patients is considerable and they suggest that this degeneration is a normal part of human aging.

These findings seem to downplay the role of the SI joint in low back pain etiology, a suggestion discussed by Dr. Ronald Lindsey in his published commentary on this article (7). Dr. Lindsey reminds clinicians that currently, no definitive test exists that can identify the SI joint as the absolute causative agent, highlighting the difficulty in establishing a definitive diagnosis. As such, he recommends that clinicians incorporate all of the relevant patient-related factors available (e.g. symptoms, history, physical examination, comorbidities, imaging, provocative studies, and psychosocial issues) in the management of a symptomatic patient. He suggests that the mere presence of degeneration on CT does not confirm this pathology as the source of the pain.

Study Methods:

Study Design:
This was a prospective analysis of pelvic CT scans over a 2 month period at a tertiary-care medical centre, plus a retrospective chart review to clarify patient history and establish inclusion/exclusion status.

Exclusion Criteria:
Patients were excluded if the indication for CT included: trauma; back, hip, or pelvic pain; or the presence of open physes or any hip or spinal instrumentation.

Outcome Measures:
All scans were reviewed by an attending orthopaedic surgeon and an orthopaedic fellow. A classification system was utilized rating SI joints as follows:
  • Type 0: free of degenerative changes
  • Type 1: mild degeneration with minimal osteophyte formation, mild subchondral sclerosis, and/or subtle joint-space narrowing
  • Type 2: substantial degenerative changes including large osteophytes, substantial subchondral sclerosis, and/or definite joint space, narrowing without ankyloses
  • Type 3: sacroiliac joint ankylosis

Study Strengths / Weaknesses:

Strengths:
  1. The study built on the original work in this area by Vogler, expanding on his cohort and using modern CT technology; and
  2. The authors utilized a logical rating scale (although this scale has not been validated).
Limitations:
  1. Some patients could have had low back pain that was not recorded during their intake/examination,
  2. The SI joint degeneration classification system has yet to be fully validated, and
  3. the patients involved were relatively old (mean age: 57.7), with only 6 patients younger than 20, thus the findings may not be generalizable to a younger population.

Additional References:

  1. Spiker WR, Lawrence BD, Raich AL, et al. Surgical versus injection treatment for injection-confirmed chronic sacroiliac joint pain. Evid Based Spine Care J 2012; 3(4): 41-53.
  2. Ledonio CG, Polly DW Jr, Swiontkowski MF. Minimally invasive versus open sacroiliac joint fusion: are they similarly safe and effective? Clin Orthop Relat Res 2014; 472(6): 1831-8.
  3. Vogler JB 3rd, Brown WH, Helms CA, Genant HK. The normal sacroiliac joint: a CT study of asymptomatic patients. Radiology 1984; 151(2): 433-7.
  4. Resnick D, Niwayama G, Goergen TG. Comparison of radiographic abnormalities of the sacroiliac joint in degenerative disease and ankylosing spondylitis. AJR Am J Roentgenol 1977; 128(2): 189-96.
  5. Resnick D, Niwayama G, Goergen TG. Degenerative disease of the sacroiliac joint. Invest Radiol 1975; 10(6): 608-21.
  6. Cohen AS, McNeill JM, Calkins E, et al. The “normal” sacroiliac joint. Analysis of 88 sacroiliac roentgenograms. Am J Roentgenol Radium Ther Nucl Med 1967; 100(3): 559-63.
  7. Lindsey RW. Sacroiliac Joint Degeneration: Forgiving, But Not to Be Forgotten. J Bone Joint Surg (Am) 2015; 97: e50(1-2).

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