Approximately 10 to 23 percent of people with ankylosing spondylitis have hip joint involvement that can be managed with tumor necrosis factor-α (TNF-alpha) blocking therapy, a study shows.
The study, “High prevalence of hip involvement and decrease in inflammatory ultrasound lesions during tumour necrosis factor-α blocking therapy in ankylosing spondylitis,” was published in the journal Rheumatology.
Ankylosing spondylitis is a rheumatic disease mainly characterized by painful inflammation of the spine and sacroiliac (where the base of the spine meets the pelvis) joints. Still, hip involvement has also been reported in patients with more severe disease.
Several anatomical structures in the hip region can be involved in the inflammatory process of ankylosing spondylitis, including the synovial membrane (which lines joints), the site where tendons or ligaments insert into the bone, and bone marrow. In addition, degeneration of the femur and pelvis joint may occur, furthering functional impairment.
Researchers now evaluated the prevalence of hip involvement in 111 ankylosing spondylitis patients with active disease and the impact of TNF-alpha blocking therapy on hip joints’ lesions.
Participants had a mean age of 42.9 years (71% male), and had the disease for a median of 15 years.
In the beginning of the study, patients were asked for a history of hip involvement and radiographic data on both hip joints to be analyzed. Clinical evaluation of tender hip joints during physical examination was also performed, as well as ultrasound examination, at baseline and six months after treatment initiation.
Initial analysis revealed that 22 (20%) patients had a reported history of hip involvement and 25 (23%) had one or more tender hip joints during physical examination. These symptoms affected both hip joints in eight (32%) of the 25 affected patients.
Ultrasound data revealed a higher prevalence of hip lesions, with 33 (30%) patients having clinically relevant hip manifestations. Of the 68 detected lesions, 38 (56%) were structural and 30 (44%) were inflammatory lesions.
Structural lesions were detected in 22 (20%) patients, which were present in both hips in 12 patients. Nineteen (17%) patients had inflammatory lesions, of which eight had bilateral involvement (both hips).
These results show that the prevalence of hip involvement in ankylosing spondylitis patients with active disease is relatively high, “varying from 10 to 23%, depending on the assessment used,” researchers stated.
Eighty-five patients were followed for six months while receiving treatment with available TNF-alpha therapies, such as infliximab (marketed as Remicade or Remsima), adalimumab (marketed as Humira or Imraldi), Simponi (golimumab), Cimzia (certolizumab), and Enbrel (etanercept).
Comparison of hip involvement before and after six months of therapy showed that the number of tender hip joints had decreased significantly, from 29 to 11. The percentage of patients with tender hip joints also significantly decreased, from 25% to 12%.
The total number of inflammatory lesions detected by ultrasound also decreased from 29 at baseline to nine after six months of TNF-alpha inhibitors.
“Based on our results, ultrasound examination of hip joints is a useful, sensitive, and objective method that contributes to the assessment of hip involvement in ankylosing spondylitis in daily clinical practice, including the evaluation of the response of TNF-a blocking therapy on inflammatory lesions,” researchers said.