I mentioned in my last post that joints are the place where bones meet. But they don’t meet in any random place that varies day to day, they meet at the same place all the time. Your leg does not bend at a different place every day. The reason for this is ligaments.

The reason for this is ligaments.

Ligaments are very tough, strong tissue that connect things together in us. They mainly connect one bone to another but there also ligament to hold our organs in place or attach the organs to the frame. You can consider ligaments the cables that hold the parts together and do so in a way that allows whatever is being connected to move in a consistent pattern without harming the parts being connected. Your knee stays put and folds where it does day after day because the ligaments prevent the bones from shifting relative to each other.

A sprain is a strain or tear of a ligament and they are slow to heal. If you think of ligaments as cables to hold things in place then it makes sense that you can’t drill holes through them to run blood vessels through. Instead, blood vessels run over the surface of a ligament and nutrients have to diffuse in and waste out. Because of this, ligaments heal slowly if they get injured. On the order of 16-20 weeks to heal completely if you are nice to them. Longer if you are not.

Which is why that ankle you sprained still talks to you months later if you just tweak it a little. Ligaments connect to the bones very firmly with the end of the ligament going through the bone surface and bonding to deeper layers. If a ligament tears off from a bone or gets ripped in half it often requires a surgical repair to get the ligament to sit in the right place to work again. Sometimes the fact that a ligament is torn will change how you can move a joint but you can still function okay such as with a separated shoulder (where the collarbone pulls off from the shoulder blade, not to be confused with a dislocated shoulder.) The ACL (anterior cruciate ligament) in the knee is often repaired, but not always, as it provides important stability to the knee.

Ligaments often have sensory organs in them to provide information to the brain about the forces it is experiencing so the brain can make judgements about how to use a joint as you move. Retraining the brain’s control of a joint after the loss of a ligament is a big part of rehab after an ACL repair because a graft is put in to replace the torn ligament, a graft without the nerve connections.

As is all connective tissues ligaments are made up mainly of collagen, a complex mixture of over 40 substances that impart both strength and flexibility. Each person’s recipe for their collagen varies as to how much of each ingredient is in the mix which contributes to the wide variations in how flexible or tight a person is in their joints and muscles.

So, now we have bones to act as levers, and ligaments to hold the bones together so the levers can work the same time after time. Next time we will look at muscles, the tissues that generate the force for moving our bodies.

– By John Macy, PT