Question
Which deformity of rheumatoid arthritis is shown below?
| A. |
Swan neck deformity
|
| B. |
Boutonniere deformity
|
| C. |
Z line deformity
|
| D. |
Piano key deformity
|
Show Answer
|
Correct Answer � B
Explanation
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|
– Boutonniere deformity is characterized by flexion of the proximal interphalangeal (PIP) joint and hyperextension of the distal interphalangeal (DIP) joint, as shown in the image.
– It occurs due to rupture or attenuation of the central slip of the extensor tendon at the PIP joint, commonly seen in rheumatoid arthritis.
Reasons to rule out other options:
– Swan neck deformity (A) involves hyperextension of the PIP joint and flexion of the DIP joint, which is opposite to Boutonniere deformity.
– Z line deformity (C) is not a commonly described deformity in rheumatoid arthritis and does not match the clinical picture here.
– Piano key deformity (D) usually refers to a deformity at the wrist or clavicle and is unrelated to the finger joint deformities seen in RA.
