In clinical practice, an anechoic signal was often exhibited between the volar plate (VP) of the proximal interphalan-geal joint (PIPJ) (PIPJVP) and the flexor digitorum tendon (FDT) on ultrasound, which suggests the presence of effusions (PIPJVP-FDT effusions). The purpose of this study was to investigate the prevalence of PIPJVP-FDT effusions and to explore the possible mechanism preliminarily.
A single-center, cross sectional study in hand osteoarthritis (HOA) patients, rheumatoid arthritis (RA) patients and healthy controls was conducted. Ultrasound examination was per-formed by the same real-time scanner with 18-MHz linear array transducer. Bilateral interphalangeal joints (IPJs) of the thumb, 2ed, 3rd, 4th and 5th PIPJs were examined. The PIPJVP-FDT effusions was defined as an anechoic signal between the PIPJVP and FDT in two perpendicular ultrasound planes.
In total, 200 patients with HOA, 78 patients with RA and 101 healthy controls were eligible for the study. 37.6% of healthy controls and 35.0% of HOA patients showed PIPJVP-FDT effusions, while only 11.5% of RA patients had PIPJVP-FDT effusions (p<0.001). The 2ed, 3rdand 4th PIPJs showed more PIPJVP-FDT effusions, while the IPJs of the thumbs and 5th PIPJs showed less PIPJVP-FDT effusions (p<0.05). Furthermore, the prevalence of PIPJVP-FDT effusions in different age groups were similar in HOA patients and healthy controls.
To the best of our knowledge, this paper is the first to demonstrate that the presence of PIPJVP-FDT effusions is a very common phenomenon in HOA patients and healthy individuals, and may be unrelated to inflammation, degeneration and age.