Background Cystic alterations of carpal bones are occasionally found on imaging examination of the wrist. These alterations could potentially confused as bone erosions in rheumatoid arthritis. Detection of bone erosion is very important in the diagnosis and treatment of rheumatoid arthritis, however very few studies have assessed on the cystic alterations of carpal bones.
Objectives To investigate the prevalence and distributing features of carpal bone cysts.
Methods We analyzed 156 three-dimensional extremity computed tomographies (CTs) on carpal bones of patients with distal radius fractures (120 women and 36 men with a mean age of 63 years). Patients with carpal bone fracture or prior arthralgia were excluded from this study. Cystic alterations on CTs were evaluated separately in each carpal bone in the sagittal, coronal and transverse planes. A carpal bone cyst was defined as a sharply marginated intraosseous radiolucent lesion (usually larger than 2 mm in size), with eccentric localization, visible in two planes.
Results CTs showed carpal bone cysts in 72 (46%) out of 156 subjects. Altogether, 121 carpal bone cysts were found in the 1404 carpal bones evaluated (4 in the trapezium, 10 in the trapezoid, 21 in the capitate 5 in the hamate, 24 in the scaphoid, 35 in the lunate, 21 in the triquetrum, and 1 in the pisiform). Cystic alterations were found more often in the older subjects. Cyst size was <4mm in 41% of all the cysts found, 4-6mm in 40%, and >6mm in 19%. 29% of the cysts had the cortical penetration in at least one plane. Mild osteoarthritic changes with subchondral sclerosis were seen in 25% of lesions.
Conclusions The distribution and frequency of cystic alterations as detected by CTs in carpal bones were identified. Cystic lesions were found frequently seen in the capitate, scaphoid, lunate and triquetrum, which also frequently show bone erosions in rheumatoid arthritis. These finding of the present study may be considered when distinguishing arthritic joints from normal joints.
Disclosure of Interest None declared