Page 53 - Imaging of Osteoarthritis and Rheumatoid Arthritis in Hand Joints

of the estimated original joint space left, 3 = bony ankylosis. Osteophytes
were defined as bony protrusions from the cortical shell and were scored for
both the trapezium and the first metacarpal. Each bone was scored as: 0 = no osteophytes, 1 = one or more small osteophytes of less than 2 mm, 2 = one or
more osteophytes larger than 2 mm. Subchondral sclerosis was defined as a
visibly increased bone density in the subchondral bone, which appeared more radiopaque than normal. The 2nd and 3rd CMC joints were used for comparing
the subchondral density. Bone cysts were defined as sharply sclerotic outlined radiolucent spots within the bone, and erosions were defined as a clear break 3 within the cortical shell. If lesions looked like a typical cyst, but had a small break
in the cortical shell, they were still considered cysts. Subchondral sclerosis, bone cysts and erosions were scored as 0 = absent, or 1= present for both the first metacarpal bone and the trapezium at the first CMC1 joint. Subluxation was calculated as a percentage of the base of the metacarpal bone that failed to cover the trapezium.
We used a reduced scoring system for the STT joint for feasibility. The STT joint was defined as the combination of the scaphotrapezial joint, the scaphotrapezoidal joint and the trapeziotrapezoidal joint. JSN, osteophytes, subchondral sclerosis, bone cysts and erosions were each scored over the whole STT joint as 0 = absent, 1 = doubtful or 2 = definite.
All images were scored by two musculoskeletal radiologists (GM and RO) with respectively 5 and 3 years of experience in evaluating hand radiographs and hand CT-scans. If both hands were imaged on both CT and radiograph, the hand in which the patient experienced the most pain was scored. The image evaluators were blinded to patient identity, clinical patient data and which CT corresponded to which radiograph. A training session to acquaint both radiologists with the scoring system was held before scoring the images.
CMC1 OA, STT OA, and Eaton and Glickel stages were derived from the scores provided. CMC1 OA was defined as the presence of JSN or an osteophyte. STT OA was defined as the presence of definite JSN or osteophyte, or as three or more STT features that were scored as doubtful. Eaton stage I was defined as no detectable CMC1 OA. Stage II was the presence of a JSN score of 1 and/or an osteophyte score of 1, without cysts or erosions in the CMC1 joint and without
CT for detection of thumb base OA
51