Radiographic damage and progression of the cervical spine in ankylosing spondylitis patients treated with TNF-α inhibitors: Facet joints vs. vertebral bodies.

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.