A blocking splint that keeps the MCP joints in extension isolates which movements?

A blocking splint that keeps the MCP joints in extension isolates which movements?

• A. MCP flexion and FDP excursion
• B. IP extension and FDP excursion
• C. IP flexion and FDP excursion
• D. Proximal IP extension and FDP excursion

Answer: (C)

Holding the MCP joints in extension with a blocking splint prevents MCP flexion and minimizes intrinsic muscle activity, so the test moves focus on the interphalangeal joints. In this setup, flexing the IP joints relies on the wrist’s flexor tendons: the FDP drives DIP flexion and the FDS drives PIP flexion. Observing IP flexion together with FDP tendon glide (FDP excursion) shows that these movements can occur independently of MCP motion. Therefore, the blocking splint isolates IP flexion and FDP excursion.

Holding the MCP joints in extension with a blocking splint prevents MCP flexion and minimizes intrinsic muscle activity, so the test moves focus on the interphalangeal joints. In this setup, flexing the IP joints relies on the wrist’s flexor tendons: the FDP drives DIP flexion and the FDS drives PIP flexion. Observing IP flexion together with FDP tendon glide (FDP excursion) shows that these movements can occur independently of MCP motion. Therefore, the blocking splint isolates IP flexion and FDP excursion.