Understanding A2 Pulley Ruptures

The A2 is the most commonly ruptured pulley in adult climbers (not kids) and is NOT common in other sports.

Loading the PIP joint at 90-degrees creates a locking mechanism (previous post) with the flexor tendons and the A2 pulley. This locking mechanism provides a mechanical advantage when using this position.

The "classic" scenario of an A2 pulley rupture looks something like this:

1. Hit a hold with a high-rate of force and "reel" it in. This contraction is part concentric/isometric.
2. Once set up on the hold, the locking mechanism is engaged. This is primarily an isometric contraction.
3. After the grip is established, the feet are moved and the center of mass changes for the athlete. This causes some eccentric load and rotational stress to the pulley.
4. The pulley might be unable to tolerate the multi-directional stress (fatigue failure), or the athlete's foot pops and "shock loads" the pulley. These typically result in an audible popping sound.

*One of the essential components of this post is understanding the location of a rupture. It is NOT common to tear the pulley itself. They are too strong. It is the attachment to the bone in which they become detached. This is why using a pulley splint is necessary. As the pulley scars down, you want it close to the bone.

Takeaways

• This post DOES NOT mean that half-crimping is "risky". We need that position to optimize leverage on small holds in many instances. But it does load the A2 pulley more than the open position.

• This post is about the A2 pulley. The full crimp position is the position which is most likely to rupture an A4 pulley. In addition, Athletes can also have multiple pulley injuries at once (A2/3), (A3/4) are common.

• These ruptures typically happen in response to weeks/months of training. The newer to climbing you are (1-2 years), the more likely they are a response to a single day of loading.

• Training habits matter most. If you've never had a pulley injury before, don't get one by adding new things to your training. You have to consider the long game with your finger training. Any sharp increases in strength are a red flag.