What is the normal capsular pattern of the interphalangeal joints 2-5?

• A. Flexion >/= Extension
• B. Extension > Flexion
• C. Flexion only
• D. Extension only

Answer: (A)

The main idea is how a damaged joint capsule restricts movement in a predictable pattern. For the finger interphalangeal joints, the capsule tightens most with flexion, so flexion is limited more than extension. In other words, you’ll see a greater loss of bending (flexion) than straightening (extension), with extension relatively preserved. That’s why the normal capsular pattern is flexion limited to a greater degree than extension. Noncapsular patterns would show selective loss of motion in only one direction (like extension only or flexion only), which isn’t typical for a true capsular involvement.