Incorporating assessment of the cervical facet joints in the modified Stoke ankylosing spondylitis spine score is of additional value in the evaluation of spinal radiographic outcome in ankylosing spondylitis

Exploring radiographic patterns of the cervical spine, including zygapophyseal joints, in axial spondyloarthritis

INTRODUCTION

The assessment of the cervical spine (CS) in axial spondyloarthritis (axSpA) and its radiographic characteristics, including the zygapophyseal joints (ZJ), may be helpful for an accurate diagnosis, establishing a prognosis and enhancing treatment decisions.

OBJECTIVES

To describe the prevalence and characteristics of CS involvement in patients with axSpA and perform a comparison between groups according to cervical radiographic damage.

METHODS

Patients who fulfilled the Assessment of SpondyloArthritis International Society classification criteria were included from January 2011 to January 2021. Sociodemographic, clinical, radiographic and treatment variables were gathered. Patients were categorised into 'CS group' (Bath Ankylosing Spondylitis Radiology Index ≥2 or De Vlam score ≥3 for ZJ) and 'no CS group' as controls. ZJ fusion and interobserver reliability in ZJ scoring were analysed.

RESULTS

A total of 340 patients were included, 244 (71.7%) men, with mean age 57±15 years. CS involvement was observed in 181 (53.2%) patients. Patients in the CS group, as compared with no CS group, were predominantly men, older, had a higher body mass index, higher prevalence of smoking, showed higher disease activity, worse functionality and mobility, as well as more structural damage. Sixty-nine patients with CS involvement had ZJ fusion at some level. These patients showed worse mobility and more radiographic damage. Overall, ZJ involvement was observed in 99 patients (29.1%), 20 of whom did not present with vertebral body involvement.

CONCLUSION

Radiographic evaluation of CS is relevant in patients with axSpA and should be assessed routinely. Evaluation of the ZJ is particularly significant, as it is related to higher disease activity and worse function.

Impact of sex on spinal radiographic progression in axial spondyloarthritis: a longitudinal Swiss cohort analysis over a period of 10 years

OBJECTIVE

To investigate sex differences in spinal radiographic progression in axial spondyloarthritis (axSpA).

METHODS

AxSpA patients in the Swiss Clinical Quality Management cohort with available spinal radiographs every 2 years were included. Paired radiographs were scored by two readers according to the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). Progression was defined as an increase of ≥2 mSASSS units in 2 years. The relationship between sex and progression was investigated with binomial generalised estimating equation models, considering baseline spinal damage as an intermediate covariate. Additional analyses included adjustments for explanatory variables and multiple imputations for missingness.

RESULTS

In a total of 505 axSpA patients (317 men and 188 women), mean±SD radiographic progression over 2 years was 1.0±2.8 years in men and 0.3±1.1 years in women (p<0.001). Male sex was associated with enhanced progression in a small model not including baseline damage (OR 3.41, 95% CI 1.87 to 6.21). Both a direct effect of male sex on spinal progression, and an indirect effect, via enhancement of baseline spinal damage were significant (OR 2.06, 95% CI 1.15 to 3.67 and OR 1.04, 95% CI 1.01 to 1.07, respectively). A significant impact of male sex on spinal radiographic progression was still demonstrated after multiple adjustments for covariates known to potentially affect spinal radiographic progression (OR 1.97, 95% CI 1.04 to 3.71).

CONCLUSIONS

Spinal radiographic progression in axSpA is more severe in men than in women, with three times higher odds of progression in male patients and an effect that is mediated in part through an increase in baseline radiographic damage.

Radiographic involvement of cervical facet joints in ankylosing spondylitis: a longitudinal analysis in correlation with vertebral body lesions

BACKGROUND

The inability to assess structural changes in facet joints is a limitation of established radiographic scoring systems for ankylosing spondylitis (AS). We compared radiographic evidence of ankylosis in cervical facet joints and cervical vertebral bodies in patients with AS.

METHODS

We analysed longitudinal data collected from 1106 AS patients and assessed 4984 spinal radiographs obtained up to 16 years of follow-up. Comparisons between cervical facet joints and cervical vertebral bodies focused on the presence of ankylosis, which was defined by at least one facet joint exhibiting complete ankylosis (according to the method of de Vlam) or at least one vertebral body with a bridging syndesmophyte (according to the modified Stoke Ankylosing Spondylitis Spinal Score [mSASSS]). Ankylosis was assessed over time using spinal radiographs collected during follow-up periods stratified in 4-year increments.

RESULTS

Patients with cervical facet joint ankylosis had higher cervical mSASSS, sacroiliitis grades, and inflammatory markers, with more prevalent hip involvement and uveitis. Overall, the numbers of spinal radiographs indicating ankylosis were comparable between cervical facet joints (17.8%) and cervical vertebral bodies (16.8%), and they usually presented together (13.5%). We observed similar proportions of radiographs with ankylosis only in cervical facet joints (4.3%) and cervical vertebral bodies (3.3%). As damage progressed, configurations with both cervical facet joint ankylosis and bridging syndesmophytes became more predominant with longer follow-up times, while configurations with cervical facet joint ankylosis only or bridging syndesmophytes only were less frequently observed.

CONCLUSIONS

Evidence of cervical facet joint ankylosis appears as often as bridging syndesmophytes on routine AS spinal radiographs. Presence of cervical facet joint ankylosis should be considered because it may have a higher disease burden.

Associations between syndesmophytes and facet joint ankylosis in radiographic axial spondyloarthritis patients on low-dose CT over 2 years

OBJECTIVES

In radiographic axial spondyloarthritis (r-axSpA), spinal damage manifests as syndesmophytes and facet joint ankylosis (FJA). We evaluated whether the presence of one lesion increased the risk of the other lesion.

METHODS

Patients with r-axSpA underwent low-dose CT (ldCT) and MRI of the whole spine at baseline and 2 years. On ldCT, vertebrae were scored for presence and size of syndesmophytes; facet joints were assessed for ankylosis. MR images were assessed for inflammation. Two hypotheses were tested: (i) presence of FJA is associated with new syndesmophyte(s) on the same vertebral unit (VU) 2 years later, and (ii) presence of bridging syndesmophyte(s) is associated with new FJA on the same VU 2 years later. Two generalized estimating equations models were tested per hypothesis using increase of FJA/syndesmophytes (model A) or presence of FJA/syndesmophytes (model B) as outcome, adjusted for inflammation at baseline. Secondary analyses tested the hypotheses with outcomes on adjacent VUs and dose-response effects.

RESULTS

Fifty-one patients were included (mean age 49, 84% male, 82% HLA-B27+). Baseline bridging syndesmophytes occurred more often (range: 10-60% per VU) than FJA (range: 8-36%). Odds ratios (ORs) (95% CI) for presence of bridging syndesmophytes on development of FJA were 3.55 (2.03, 6.21) for model A and 3.30 (2.14, 5.09) for model B. ORs for presence of baseline FJA on new syndesmophytes were 1.87 (1.20, 2.92) for model A and 1.69 (0.88, 3.22) for model B. Secondary analyses yielded positive ORs for both hypotheses.

CONCLUSIONS

Bone formation in vertebrae and in facet joints influence each other's occurrence, with the effect of syndesmophytes being larger than that of FJA.

Association between facet joint ankylosis and functional impairment in patients with radiographic axial spondyloarthritis

OBJECTIVES

To investigate the occurrence of facet joint ankylosis in the spine of patients with radiographic axial spondyloarthritis (r-axSpA) using low dose computed tomography (ldCT), and to examine the association between facet joint ankylosis and functional impairment.

METHODS

A group of 126 patients with r-axSpA was selected from Incheon Saint Mary's axSpA observational cohort and whole spine ldCT data were examined. Facet joint (right and left, C2-S1) ankylosis was scored from 0-46 (total). The presence of facet joint ankylosis was assessed by two readers, each blinded to the patient data. The inter-reader reliability of facet joint ankylosis scoring was assessed using intraclass correlation coefficients (ICCs). The CT Syndesmophyte Score (CTSS) was assessed. Lumbar spinal mobility was evaluated using the modified Schober test. Functional impairment was measured using the Bath AS functional index (BASFI).

RESULTS

The ICCs of ankylosed facet joint scores at the cervical, thoracic, lumbar and whole spine were 0.84, 0.88, 0.92 and 0.90, respectively. Facet joint ankylosis was most common in the thoracic spine. Scores for the whole spine correlated positively with the ASDAS, mSASSS and the syndesmophyte score. Multivariate analysis revealed that facet joint ankylosis was significantly associated with decreased lumbar motion. For both readers, the scores for the whole spine were independently associated with BASFI after adjusting for syndesmophyte score and disease activity.

CONCLUSIONS

Facet joint ankylosis in patients with r-axSpA was associated with functional impairment and spinal mobility. Facet joints should be incorporated into a structural damage assessment method.

Facet joint ankylosis in r-axSpA: detection and 2-year progression on whole spine low-dose CT and comparison with syndesmophyte progression

Objectives

To evaluate the occurrence and progression of facet joint ankylosis in the whole spine using low-dose CT (ldCT) in radiographic axial spondyloarthritis (r-axSpA) and compare progression of facet joint ankylosis and syndesmophytes.

Methods

Patients with r-axSpA from the Sensitive Imaging in Ankylosing Spondylitis (SIAS) cohort underwent ldCT at baseline (n = 60) and 2 years (n = 53). Facet joints (right and left, levels C2-S1) were scored as ankylosed, not ankylosed or unable to assess. Joints that were frequently poorly visible (>15% missing), were excluded. Inter-reader reliability on the patient level was assessed with intraclass correlation coefficients (ICCs) and smallest detectable change (SDC). Ankylosis was assessed at joint level and patient level for both timepoints. Syndesmophytes were assessed with CT syndesmophyte score.

Results

Levels C5-T2 were difficult to assess and excluded from all further analyses. Facet joint ICCs were good to excellent for status scores (0.72–0.93) and poor to excellent for progression scores (0.10–0.91). Facet joint ankylosis was detected at every level but most frequently in the thoracic joints. In total, 48% of patients showed 2-year progression. Most progression occurred in the thoracic segment. Using SDCs as cutoff, 18% of patients had progression of facet joint ankylosis only, whereas 20% of patients had progression of syndesmophytes only.

Conclusion

This is the first study evaluating facet joints in the whole spine by ldCT in r-axSpA. Facet joint ankylosis was detected most often in the thoracic spine. Assessing facet joints in addition to syndesmophytes detected substantially more patients with damage progression over two years.

Differential Diagnosis of Facet Joint Disorders

Spinal pain due to facet joint disease is difficult to diagnose since the clinical history and physical examination findings are usually nonspecific. Facet joint disorders have a wide range of causes and, because of the potential for chronic back pain and disability, an accurate diagnosis is essential. The most frequent cause of pain in facet joints is osteoarthritis, which can be assessed at radiography, CT, or MRI. Ganglion and synovial cysts of the facet joints can cause compressive symptoms of adjacent structures, especially radiculopathy, lower back pain, and sensory or motor deficits. In ankylosing spondylitis, imaging findings of the facet joints are useful not only for diagnosis but also for monitoring structural changes. In septic arthritis of the facet joints, an early diagnosis at MRI is essential. Gout and metabolic diseases are best evaluated at dual-energy CT, which allows the depiction of crystals. Traumatic dislocations of facet joints are usually unstable injuries that require internal reduction, fixation, and fusion and can be well assessed at CT with three-dimensional reconstructions. Facet joint neoplasms like osteoid osteoma, plasmacytoma, tenosynovial giant cell tumor, and osteochondroma are best evaluated at CT or MRI. The authors provide an overview of key imaging features of the most common facet joint disorders along with anatomic tips and illustrative cases. Acknowledging key imaging findings for the differential diagnosis of facet joint disorders plays a crucial role in the diagnostic accuracy and proper treatment approach for such entities. Online supplemental material is available for this article. ^©RSNA, 2021.

Update of imaging in the diagnosis and management of axial spondyloarthritis

Imaging of the spine and sacroiliac joints has acquired a central role in the diagnosis and classification of axial spondyloarthritis (axSpA) in the earliest phases of the disease. New definitions of specific imaging lesions, particularly in magnetic resonance imaging (MRI), have been recently updated and revised by the ASAS MRI working group to reach a standardized understanding and diagnosis of axSpA among rheumatologists. Recognizing the misleading pitfalls of MRI lesions and differential diagnosis also represents an essential issue in clinical practice to avoid false-positive findings and establish the diagnosis of axSpA with careful regard to the clinical context, clinical signs, and biological tests. This review summarizes the current evidence on the different imaging modalities of the sacroiliac joints and the spine with their application in the clinical setting of SpA and their main pitfalls; it also highlights the newest emerging imaging techniques.

Consequences of spinal ankylosis on bone trabecular fragility assessed on CT scans in patients with ankylosing spondylitis. A retrospective study

INTRODUCTION

Ankylosing spondylitis (AS) patients seems to be at risk of osteoporosis but bone screening is not often performed. The objective was to evaluate the effect of vertebral ankylosis on scanographic bone attenuation coefficient (SBAC) on lumbar vertebrae in AS patients.

METHODS

This study included AS patients fulfilling New York criteria who underwent both thoraco-abdomino-pelvic computed tomography and X-rays during routine follow-up. The modified stoke ankylosing spondylitis spinal score (mSASSS) was scored on X-rays, and the presence of at least one syndesmophyte (mSASSS≥2) defined mSASSS+ patients. Ankylosis of a lumbar vertebra was defined by the presence of bone bridges to its two adjacent vertebrae. The SBAC was measured from L1 to L5, and the fracture threshold was set at SBAC≤145 HU.

RESULTS

A total of 73 AS patients were included (mean age: 60.3 [±10.7] years, 65 men [89%]). Sixty patients (82.2%) were mSASSS+; 13 patients (17.8%) presented ankylosis of at least one lumbar vertebra. The SBAC of each lumbar vertebra was not significantly different between mSASSS- and mSASSS+ patients. The SBAC was lower for patients with at least one bone bridge than for patients without (P<0.05). Patients with lumbar vertebral ankylosis had a higher risk of presenting an SBAC≤145 HU (OR: 4.95 (95% CI: 1.1-17.4)).

CONCLUSION

The presence of a bone bridge and complete ankylosis of lumbar vertebra were associated with a higher risk of SBAC under the fracture threshold, suggesting structural deterioration of trabecular bone in ankylosed vertebrae in AS patients.

Effect of Therapy on Radiographic Progression in Axial Spondyloarthritis: A Systematic Review and Meta-Analysis

OBJECTIVE

To investigate the effect of therapies on radiographic progression in patients with axial spondyloarthritis (SpA).

METHODS

A comprehensive database search for studies assessing radiographic progression in axial SpA (particular treatment versus no treatment of interest) was performed. Study-specific standardized mean differences in treatment outcomes at 2 and ≥4 years were estimated and combined using random-effects models.

RESULTS

Twenty-four studies in patients with axial SpA were identified, of which 18 involved tumor necrosis factor inhibitors (TNFi), 8 involved nonsteroidal antiinflammatory drugs (NSAIDs), and 1 involved secukinumab. Spinal radiographic progression, as measured by the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), was not significantly different between TNFi-treated and biologics-naive patients at 2 years (mSASSS difference -0.73 [95% confidence interval (95% CI) -1.52, 0.12], I2 = 28%) and ≥4 years (mSASSS difference -2.03 [95% CI -4.63, 0.72], I2 = 63%). Sensitivity analyses restricted to studies with a low risk of bias showed a significant difference in spinal radiographic progression between TNFi-treated and biologics-naive patients at ≥4 years (mSASSS difference -2.17 [95% CI -4.19, -0.15]). No significant difference in spinal radiographic progression was observed between NSAID-treated and control patients (mSASSS difference -0.30 [95% CI -2.62, 1.31], I2 = 71%) or between secukinumab-treated and biologics-naive patients (mSASSS difference -0.34 [95% CI -0.85, 0.17]). With regard to treatment differences in patients with nonradiographic axial SpA or in patients with radiographic progression measured using the sacroiliac joint score, an insufficient number of studies were available for analysis.

CONCLUSION

Although no significant protective effect of TNFi treatment on spinal radiographic progression was seen over the course of 2 years or ≥4 years in patients with axial SpA, our analysis restricted to studies with a low risk of bias showed a protective effect of TNFi after ≥4 years. Therefore, long-term TNFi exposure might confer beneficial effects on spinal radiographic progression in axial SpA. No difference in radiographic progression at 2 years was seen in either the NSAID or secukinumab treatment groups compared to their controls. Future studies should explore the effects of biologic treatment on radiographic progression, as well as the effects of long-term biologics exposure, in patients with early axial SpA or those with nonradiographic axial SpA.

Modified stoke ankylosing spondylitis spinal score as an outcome measure to assess the impact of treatment on structural progression in ankylosing spondylitis

In ankylosing spondylitis (AS), structural damage that occurs as a result of syndesmophyte formation and ankylosis of the vertebral column is irreversible. Structural damage is currently assessed by conventional radiography and scoring systems that reliably assess radiographic structural damage are needed to capture the differential effects of drugs on structural damage progression. The validity of the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) as a primary outcome measure in evaluating the effect of AS treatments on radiographic progression rates was assessed in this review. The mSASSS has not been used, to date, as a primary outcome measure in a prospective randomized controlled clinical trial of biologic therapy in AS. This review of the medical literature confirmed that the mSASSS is the most validated and widely used method for assessing radiographic progression in AS, correlating with worsening measures of disease signs and symptoms, spinal mobility and physical function, with a 2-year interval being required to ensure sufficient sensitivity to change.