A PIP extension block splint sits on the back of the finger and stops the middle joint straightening past a set angle, while letting it BEND FREELY.
It’s used for volar plate injuries and stable PIP fracture-dislocations, where the joint stays in place when bent but slips out as it straightens.
The block is reduced step by step over about four to six weeks, until the finger straightens fully on its own.
Why block straightening but allow bending
- The volar plate is the thick ligament on the palm side of the middle joint. It stops the joint bending backwards
- When it tears or pulls off a fragment of bone, the joint can slide backwards out of place, especially near full straightening
- Bent, the joint stays reduced. The block keeps it in that safe range
- Bending freely keeps the joint moving, which is what prevents the stiffness this joint is notorious for
Stable when bent, unstable when straight. The splint lets the finger live in the stable half.
What it’s used for
- Volar plate injuries from a finger bent backwards, the classic ball-sport injury. See jammed finger and ball sports
- Stable PIP fracture-dislocations that stay in place in the splint
- After surgery on the middle joint, such as volar plate repair
- PIP dislocations that were put back and feel unstable near full straightening
The X-ray that matters
A side-on X-ray is taken WITH the splint on.
The joint surfaces should sit evenly against each other. If a gap opens at the back of the joint, the block angle isn’t enough or the injury needs a different plan.
A typical timeline
- Week 0 to 1: block set at the angle where the joint stays in place, often around 20 to 30 degrees short of straight. Bend the finger fully many times a day
- Weeks 1 to 4: block reduced a little each week, typically by about 10 degrees, with a repeat X-ray if the fracture is involved
- Weeks 4 to 6: splint off. Full straightening encouraged, buddy strapping for activity
- Months 2 to 6: the joint can stay thick and slightly stiff for months while it matures
Problems to watch for
- A finger that stops straightening once the block is gone. Flexion contractures are the common long-term problem
- Pressure on the back of the middle joint
- Not bending enough inside the splint, which lets the joint stiffen in the protected position
- Straps loosening, so the finger straightens past the block at night
Get it checked if
- A clunk or visible step at the joint
- The finger slips out of line again
- Numbness or color change
- Straightening still limited well after the splint is off
This is one of dozens of splints a hand therapist makes. See what a hand therapist does for the full list, and finger joint anatomy for why the middle joint behaves this way.
Block the straightening, keep the bending, and take the block away a step at a time.
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.