Ultrasonographic evaluation of femoral cartilage thickness in patients with ankylosing spondylitis.

OBJECTIVE: To evaluate femoral cartilage thickness in patients with ankylosing spondylitis (AS) by using ultrasonography. METHODS: Eighty-four patients (55 M, 29 F) with a diagnosis of AS and 84 age-, gender- and body mass index-matched healthy subjects were enrolled. Demographic and clinical characteristics of the patients including disease duration, morning stiffness and medications were recorded. The femoral cartilage thicknesses of both knees were measured with a 7-12 MHz linear probe while subjects' knees were held in maximum flexion. Three mid-point measurements were taken from both knees (lateral femoral condyle (LFC), intercondylar area (ICA) and medial femoral condyle (MFC)). RESULTS: Concerning both ICA (p < 0.001) and left MFC (p = 0.013), cartilage measurements were significantly thicker in AS patients than control subjects. In a subgroup analysis (anti-tumour necrosis factor (TNF) users vs anti-TNF naive), cartilage thickness measurements - bilateral ICA (p = 0.000) and left MFC (p = 0.017) - were found to be greater in AS patients under anti-TNF treatment (n = 65) when compared with those of healthy controls. CONCLUSION: We imply that AS patients seem to have thicker femoral cartilage, which could be related to anti-TNF treatment.