How to measure wrist range of motion

• Flexion — bending the palm towards the inside of the forearm.
• Extension — bending the back of the hand towards the outside of the forearm.
• Radial deviation — tilting the hand towards the thumb side.
• Ulnar deviation — tilting it towards the little-finger side.
• Turning the palm up and down is forearm rotation, not a wrist movement — see the elbow page.

Usually with the forearm resting on a table and the hand free over the edge. The pivot sits at the wrist, one arm along the forearm and the other along the hand, and the angle is read at the end of the movement. Flexion and extension are measured with the palm down; deviation with the palm flat and the hand sliding sideways.

The wrist angle is made from the elbow, the wrist and the index point — the pose model's marker for the base of the index finger, which gives the hand its far end. A straight wrist, the hand in line with the forearm, reads 180°. The distance from 180° is how far the wrist is bent.

Which bend you are reading depends on the camera. To read flexion and extension, film the thumb side of the hand, so the hand bends across the picture. To read radial and ulnar deviation, film the palm or the back of the hand, so it tilts across the picture instead. Either way, the other direction of movement happens towards or away from the camera and reads short.

The wrist is one of the six joints Markerless calculates from the landmarks rather than measures with the engine, and every figure and download says so. Measurements analysed before the index point was stored have no wrist angle, rather than a guessed one.

Filmed front-on, a person's two sides are mirror images in the picture, so the same movement reads x on one side and 360 − x on the other. The report flips the mirrored side back so left and right sit on the same scale; the downloads keep the engine's own clockwise angles.

1. Rest the forearm on a table so it stays still; the elbow must stay in frame.
2. For flexion and extension, put the camera level with the thumb side of the hand.
3. For deviation, put it above or in front of the palm.
4. Get close: the hand is small, and the model's hand points need it clearly in view.
5. Keep the fingers together and relaxed, so the index point follows the hand.
6. Film the same way each time.

The full-body pose model marks the hand with only a few approximate points — the index finger, the little finger and the thumb — not the bones of the wrist. That makes the wrist angle coarser than the elbow or knee, and a curled or spread hand moves the index point and the reading with it.

Forearm rotation is invisible to it, and so is any movement out of the filmed plane. If the wrist is what you need to measure in detail, a dedicated hand-tracking model will see more of the hand than a whole-body one.