LAUSR

OBJECTIVES To investigate radiographic damage and 4-year progression of the cervical facet joints in a prospective observational cohort of AS patients treated with TNF-α inhibitors, to compare this with damage and progression of the cervical vertebral bodies, and to study the relation with patient characteristics and clinical outcome. METHODS Patients from the Groningen Leeuwarden AS (GLAS) cohort starting TNF-α inhibitors with baseline and 4-year radiographs were included. Cervical facet joints and vertebral bodies were scored by two independent readers according to the method of de Vlam and mSASSS, respectively. RESULTS At baseline, 25 of 99 (25%) AS patients had partial or complete ankylosis of the cervical facet joints, whereas 51 (52%) patients had non-bridging or bridging syndesmophytes of cervical vertebral bodies. During 4 years, 13 (13%) patients developed new (partial) ankylosis of the facet joints, whereas 26 (26%) developed new (bridging) syndesmophytes. Facet joint damage and progression without involvement of the vertebral bodies were seen in 5 (5%) and 8 (8%) patients, respectively. Damage of facet joints was associated with longer disease duration, history of IBD/uveitis/psoriasis, higher disease activity, larger occiput-to-wall distance, higher mSASSS, and presence of syndesmophytes. Progression of the facet joints was associated with larger occiput-to-wall distance and more facet joint damage at baseline. CONCLUSIONS Cervical facet joints were frequently involved in AS. During 4 years of TNF-α blocking therapy, 13% of the patients showed radiographic progression of cervical facet joints of which the majority did not show progression of vertebral bodies.