1. The Z-splint is the Position of Safe Immobilisation, as this allows collateral ligaments to be positioned on a stretch, thereby limiting tightness of these ligaments.
2. The wrist is 30° extended, MCP 70°–90° flexed and IP’s extended.
3. Use this splint in any hand or finger injury that needs to be immobilised.
4. Use this splint to immobilise infective conditions.

Steps of applying a POSI Z-splint

1. It is easiest if the patient lies on their back and their hand is fully supinated facing to the roof.
2. Wrap the whole forearm to the fingers with velband or webril.
3. Use 2100mm gypsona casts and make it the length of two hand spans.
4. Use a buttress under the distal radius to allow the wrist to fall back in 30° extension.
5. Apply the cast to the volar (palmar) side of the hand and ensure the cast is long enough to support the full length of the middle finger.
6. Work the cast into the depth of palm and try to obtain maximum MCP flexion whilst keeping the fingers straight.
7. Ensure the cast does not limit elbow flexion and extension.
8. Wrap this up with a bandage (elastoform).
9. It is preferable to see the fingertips