What is the typical position of the MCPs when casting for a WHO?

When casting for a wrist-hand orthosis (WHO), the typical position for the metacarpophalangeal joints (MCPs) is indeed in a range of 35-40 degrees of flexion. This position is crucial for ensuring proper function of the orthosis, allowing for optimal finger positioning to enable both grip and pinch.

Flexing the MCP joints allows for the natural prehension and function of the hand while maintaining a relaxed and functional posture. If the MCPs are casted at a more extended position, it could lead to increased stiffness and discomfort in the hand. Furthermore, a too aggressive flexion or lack of support can hinder the thumb’s and fingers’ functional use, which is why the specific degrees of flexion are important in the design of these orthotic devices.

This precise positioning helps to optimize hand function and improve the overall effectiveness of the orthosis in assisting patients with various hand-related conditions or injuries.