Ankylosing spondylitis

Ankylosing spondylitis (AS) is a type of arthritis in which there is long term inflammation of the joints of the spine. Typically the joints where the spine joins the pelvis are also affected. Occasionally other joints such as the shoulders or hips are involved. Eye and bowel problems may also occur. Back pain is a characteristic symptom of AS, and it often comes and goes. The stiffness of the affected joints generally worsens over time.
Although the cause of ankylosing spondylitis is unknown; to involve a combination of genetic and environmental factors. More than 90% of those affected have a specific human leukocyte antigen known as the HLA-B27 antigen. The underlying mechanism is believed to be autoimmune or autoinflammatory.  Diagnosis is typically based on the symptoms with support from medical imaging and blood tests. AS is a type of seronegative spondyloarthropathy, meaning that tests show no presence of rheumatoid factor (RF) antibodies.

High Prevalence of hip

Patients with ankylosing spondylitis (AS) showed a high prevalence of hip involvement at a rate of 10% to 23%; depending on the method of assessment, according to a study published in Rheumatology. Data also show that 6 months of tumor necrosis factor-α (TNF-α)  inhibitor therapy resulted in a significant decrease in tender hip joints; inflammatory ultrasound lesions, and positive power Doppler signals.

This daily clinical practice observational cohort study to assess the prevalence of ultrasound, radiographic, and clinical hip involvement in patients with active AS; to identify associations between the assessments, and to evaluate the effect of 6 months of TNF-α inhibitor therapy. Participants beginning TNF-α inhibitor therapy were first assessed for hip joint involvement; a baseline radiographic evaluation is using the Bath Ankylosing Spondylitis Radiology Index of the hip, and participant history of hip involvement.

Ultrasound and clinical examinations

Therefore ultrasound and clinical examinations of hip joints are at baseline and after 6 months of treatment. Of 111 participants; 20% reported a history of hip involvement and 23% had tender hip joints at baseline. So a moderate correlation is between the history of hip involvement and radiographic hip involvement (phi coefficient, 0.333; <.05). A weak correlation between structural ultrasound lesions and tender hip joints (phi coefficient, 0.193; <.05) and radiological hip involvement (phi coefficient 0.203; <.05).
No significant correlation with any other assessment; only 2 patients with inflammatory ultrasound lesions also reported a painful hip. After participants received 6 months of TNF-α inhibitor therapy; the total number of inflammatory ultrasound lesions decreased from 29 to 9, positive power Doppler decreased from 22 to 6, and tender hip joints decreased from 29 to 11.
In conclusion, the percentage of total participants with tender hip joints significantly decreased from 25% to 12% (<.05). Study investigators conclude, “based on our results, [ultrasound] examination of hip joints is a useful, sensitive and objective method that