This is yet another phrase I haven’t seen in a few years that I saw the other day doing my chart reviews. This goes for every joint in the body. Depending on the position you place the joint in, it’s called either open or closed pack. Open pack means the joint is all loosey-goosey, that the ligaments holding the joint together are not taut. The joint is considered rather unstable in the open pack position. Closed-pack position is the opposite. The ligaments surrounding the joint are pulled taut. A sprain of a ligament usually will happen when a joint is in closed pack position and an extreme force is applied. I mean if the force is great enough a sprain or tear can happen in the open pack position too. In the open pack position the joint is really unstable so…you have more of a chance of performing a movement that will cause an extreme force because of the instability of the joint so forget what I just said I’m just thinking out loud. No I’m not, I’m thinking out typing??? Whatever. Think of the elbow, easy example. Straighten the arm, your forearm barely moves – that’s closed pack. Bend the arm 70 degrees, it’s a heck of a lot easier to move the forearm around right? That’s open pack. When performing joint mobilizations, the joint should be placed in the open pack position.