To sonographically characterize pseudoerosions and dorsal joint recess and capsule morphology of the hand and wrist in 100 asymptomatic subjects.

The metacarpal heads, and dorsal aspects of the lunate, triquetrum, and ulna were evaluated for pseudoerosions including measurements and sonographic characterization. The dorsal recesses of the metacarpophalangeal, radiocarpal, and midcarpal joints were also characterized with regards to echogenicity, fibrillar pattern, hyperemia, and measurements.

100 subjects were included (average age 47 years, range 19-82 years; 52% male, 48% female). Pseudoerosions of metacarpophalangeal heads were seen in every subject, in all metacarpal heads, but most commonly the second and third (99% were bilateral, 97% were multiple); 81.5% involved at least three metacarpal heads; 99% were central with maximum depth of 2.6 mm. At the wrist, in 92% of subjects a bilateral pseudoerosion was present at the dorsal triquetrum, lunate, or ulna. Dorsal joint capsules and recesses at the metacarpophalangeal joints were isoechoic to subdermal fat and fibrillar measuring 3.1-6.3 mm in maximal thickness. The dorsal capsules and recesses of the radiocarpal and midcarpal joints were hypoechoic to subdermal fat, non-fibrillar and with maximal thickness of 3.9 and 3.4 mm, respectively. No hyperemia on color Doppler imaging was noted.

Pseudoerosions are common at the dorsal metacarpal heads, lunate, triquetrum, and ulna, which should not be mistaken for true inflammatory erosions. The characteristic appearances of dorsal joint capsules and recesses should not be confused with synovial hypertrophy.