National Physical Therapy Examination (NPTE) Practice Exam

A 45-year-old female with rheumatoid arthritis shows increased flexion at proximal interphalangeal joints and hyperextension at distal interphalangeal joints. What is the most likely diagnosis?

1. Boutonniere deformity

2. Mallet finger

3. Swan Neck deformity

4. Ulnar drift

The correct answer is: Boutonniere deformity

The presentation of increased flexion at the proximal interphalangeal (PIP) joints combined with hyperextension at the distal interphalangeal (DIP) joints is characteristic of the swan neck deformity. This adaptive posture results from the imbalance of the flexor and extensor tendons due to joint instability commonly seen in rheumatoid arthritis. In swan neck deformity, the extension of the DIP joint occurs alongside the simultaneous flexion of the PIP joint due to the specific alterations in the soft tissue surrounding the joints. This condition is a direct result of the synovitis and subsequent joint destruction caused by rheumatoid arthritis, which affects the tendons and ligaments that stabilize the fingers. Recognizing swan neck deformity is crucial in the management of patients with rheumatoid arthritis, as it indicates the need for appropriate interventions to enhance function and alleviate discomfort. The other conditions listed—such as boutonniere deformity, where the PIP joint is flexed and the DIP is hyperextended due to a rupture of the central slip of the extensor tendon; mallet finger, which is characterized by the inability to extend the DIP joint due to a tendon injury; and ulnar drift, which refers to the lateral deviation of the