The condition described involves a deformity where the proximal interphalangeal (PIP) joint is affected but the distal interphalangeal (DIP) joint is spared. This pattern is characteristic of Rheumatoid arthritis.
Osteoarthritis: Typically presents with involvement of both PIP and DIP joints, particularly Heberden's nodes at the DIP and Bouchard's nodes at the PIP.
Rheumatoid arthritis: Primarily affects the PIP and metacarpophalangeal (MCP) joints, sparing the DIP joints. Deformities such as swan neck and boutonniere are common.
Psoriatic Arthritis: Can affect PIP and DIP joints but often associated with skin changes and nail pitting.
Ankylosing spondylitis: Primarily affects the spine and sacroiliac joints, not typically associated with finger joint deformities.
Therefore, based on the presentation where only the PIP joint is affected and the DIP is spared, the correct answer is Rheumatoid arthritis.
