A first web space splint, often called a C-BAR, holds the thumb stretched away from the index finger so the skin and muscle between them can’t tighten.
It’s used after burns, crush injuries and scar across the web, after surgery to release a tight web, and when nerve damage stops the thumb opening on its own.
A web that shrinks by even a small amount makes it hard to grip a bottle, a steering wheel or a cup.
Why the web space matters
- The web between thumb and index finger is what lets the hand open wide around large objects. See thumb anatomy
- After injury, the hand rests with the thumb pulled in. Left that way, skin, scar and the muscle in the web shorten
- Once shortened, it takes months of stretching, splinting or surgery to open again
- Prevention is far easier than correction
You don’t notice the web until it’s tight. Then you notice it every time you pick something up.
What it’s used for
- Burns to the web, back of the hand or palm, often alongside silicone gel and pressure garments
- Crush injuries with heavy swelling in the thumb and web
- After web space contracture release or skin grafting
- Median nerve injury, where the thumb can’t lift away from the palm, and before or after tendon transfers to restore that movement
- Spasticity, after stroke or brain injury, where the thumb pulls tightly into the palm
The designs
- Hand-based C-bar: a curved piece of thermoplastic shaped to the web, strapped around the hand
- Forearm-based thumb abduction splint: when the wrist also needs support
- Soft web spacers: foam or silicone, for night use and for burns where rigid pressure isn’t tolerated
- Serial splints: remolded wider as the web gains length
How long
- After burns: at night, and often between daytime sessions, for as long as the scar is active. Burn scar can keep tightening for 12 to 18 months
- After a crush injury: mainly at night for the first 4 to 6 weeks, while swelling settles
- After contracture release: full time early, then nights for several months
- Nerve injury: until the nerve recovers or a tendon transfer takes over
Problems to watch for
- Pressure on fragile grafts or new scar
- Stretching the wrong joint. The force should open the web, not bend the thumb knuckle backwards
- Sweat and blistering in the web crease
- A splint that no longer reaches the new end of range
Get it checked if
- Blisters or broken skin in the web
- The web getting tighter despite wearing it
- The thumb knuckle starting to bend backwards
This is one of dozens of splints a hand therapist makes. See what a hand therapist does for the full list, and scar management for the treatments that go alongside it.
Keep the web open while it heals, because reopening it later is much harder.
Every article on this site is written using the Closing Window Method: name the window your condition runs on, find where you are in it, and act while it’s still open.