Background The destruction of cartilage is one of the basic mechanisms of the progression of hand osteoarthritis (HOA). Radiographic study indicates the thickness of the cartilage indirectly based on the degree of joint space narrowing (JSN). At the same time, the ultrasound (US) method allows to measure it directly.
Objectives To determine the thickness of the cartilage in the interphalangeal joints of patients with HOA and to correlate this rate with the degree of JSN, identified by radiologic imaging.c imaging.
Methods 45 women at the age of 45 – 75 years were included in the research. All of them were diagnosed of HOA according to the criteria of American College of Rheumatology (ACR). For each patient 8 proximal interphalangeal joints (PIP) were surveyed. The conventional radiographs (CRs) of each hand were performed for all patient in the standard frontal projection and the radiological changes were assessed using Kallman's method. Next, US investigation was carried out. The thickness of the cartilage was measured in the central part of the 2–5 proximal phalanx heads of both hands in the dorsal longitudinal view in the static image in gray- scale with the flexion position no more than 90 degrees. The cartilage is defined as a thin hypoechoic smooth layer, paralleling the contours of the articular surface. The thickness of the cartilage was defined as the distance between the subchondral bone and the surface layer of cartilage, which was the border between the cartilage and the joint cavity. In the presence of synovitis measurement of joint cartilage was carried out before the border and hypertrophic synovial if they differed in the degree of intensity of the US signal. The measurement of cartilage thickness was carried out by a conventional line, which was an exact perpendicular to the surface of the subchondral bone and parallel to the direction of US waves. Measurement was not carried out if visualization of the surface layer of cartilage was not possible. The control group consisted of 45 women 45–75 years old without HOA, but with ultrasound investigation. Data were analyzed using Statistica 10.0 and are presented as mean (standard deviation), “odds ratio” coefficient (OR) and χ 2 Pearson's correlation coefficient.
Results 360 joints of both hands were investigated with successful measurement of the cartilage thickness of 338 (94.7%) joints. The average value of the cartilage in all PIP was 0.31 (0.11) mm. The maximum thickness of the cartilage was obtained in the 2nd PIP joints - 0.34 (0.12) mm on the right hand and 0.36 (0.14) mm on the left hand. For the control group results were 0.38 (0.11) mm and 0.37 (0.13) mm respectively. We have found a reliable relationship between the degree of JSN and cartilage thickness with the OR 1.849 (95% confidence interval 1.198 – 2.855), χ2 =7.772, p=0.0053.
Conclusions US reduction of the cartilage thickness is a marker of cartilage loss which is correlated with the results of radiologic examination. This makes possible to use ultrasound as an alternative method of diagnosing HOA.
Disclosure of Interest None declared