Answer for CoW 12 March 2017
KEINBOCKS DISEASE- STAGE 3
Findings
Diffusely decreased signal intensity and size is present within the lunate.
Discussion
The large majority of the lunate is covered with articular cartilage, leaving only small areas accessible to nutrient vessels along the dorsal and volar poles. These “bare areas” correspond to ligamentous insertion sites, and thus trauma may result in avulsion injuries to the entering arteries. Internally, the lunate blood supply forms patterns resembling a Y (59%), an I (31%), or an X (10%). Kienbock’s disease may be staged based upon its MR appearance: Stage 0 -MR reveals a linear fracture line within the mid lunate on T1-weighted images without a diffuse marrow signal abnormality. Plain films are normal. Stage I -MR demonstrates focal or diffusely decreased signal intensity on T1-weighted images. T2*-weighted images reveal low signal intensity, perhaps due to hemorrhage, though hyperintensity may be present on STIR or fat-suppressed T2-weighted exams. Plain films remain normal. Stage II -Progressively decreased signal intensity on T1-weighted images and heterogeneously increased signal on T2-weighted images is present. Sclerosis is evident on plain films. Stage III – The lunate undergoes progressive collapse in the coronal plane and elongation in the sagittal plane. Associated scapholunate ligamentous tearing with rotary subluxation of the scaphoid takes one from IIIA to IIIB. Stage IV – All of the stage III features are present in addition to generalized arthritic changes at the carpus.
Findings
Diffusely decreased signal intensity and size is present within the lunate.
Discussion
The large majority of the lunate is covered with articular cartilage, leaving only small areas accessible to nutrient vessels along the dorsal and volar poles. These “bare areas” correspond to ligamentous insertion sites, and thus trauma may result in avulsion injuries to the entering arteries. Internally, the lunate blood supply forms patterns resembling a Y (59%), an I (31%), or an X (10%). Kienbock’s disease may be staged based upon its MR appearance: Stage 0 -MR reveals a linear fracture line within the mid lunate on T1-weighted images without a diffuse marrow signal abnormality. Plain films are normal. Stage I -MR demonstrates focal or diffusely decreased signal intensity on T1-weighted images. T2*-weighted images reveal low signal intensity, perhaps due to hemorrhage, though hyperintensity may be present on STIR or fat-suppressed T2-weighted exams. Plain films remain normal. Stage II -Progressively decreased signal intensity on T1-weighted images and heterogeneously increased signal on T2-weighted images is present. Sclerosis is evident on plain films. Stage III – The lunate undergoes progressive collapse in the coronal plane and elongation in the sagittal plane. Associated scapholunate ligamentous tearing with rotary subluxation of the scaphoid takes one from IIIA to IIIB. Stage IV – All of the stage III features are present in addition to generalized arthritic changes at the carpus.
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!