Orthopaedic Nurses Certification Board (ONCB) Metabolic/Inflammatory/Tumors Practice Exam

Which deformity is recognized as a "zigzag" wrist deformity associated with rheumatoid arthritis?

1. Swan-neck deformity

2. Boutonniere deformity

3. Ulnar deviation

4. Phalangeal retraction

The correct answer is: Ulnar deviation

The "zigzag" wrist deformity associated with rheumatoid arthritis is recognized as ulnar deviation. This deformity occurs due to the progressive damage to the joint structures caused by inflammation and synovitis, typical of rheumatoid arthritis. As the disease advances, the ligaments and tendons supporting the wrist become lax, leading to the characteristic bending of the fingers toward the ulnar side, resulting in a zigzag appearance when viewing the wrist and fingers. Ulnar deviation is specifically distinguished from conditions such as swan-neck deformity, which involves hyperextension of the proximal interphalangeal joint and flexion of the distal interphalangeal joint, or boutonniere deformity, where the proximal interphalangeal joint is flexed while the distal interphalangeal joint is hyperextended. Phalangeal retraction is not a widely recognized term but could refer to finger positioning changes without specifically addressing the ulnar deviation seen in arthritis. The unique presentation of ulnar deviation makes it the primary deformity associated with this condition.