Should I be concerned about knee hyperextension?
Let’s start by defining hyperextension. This is a word that can be confusing because it can be used in two different ways. The first way that the term hyperextension can be used is to describe a basic, normal movement. Hyperextension is extension past the point of “neutral” when we are standing in anatomical position. So, if I extend my arm at the shoulder joint from a flexed position and return it to my side, I have done extension of the shoulder joint. If I keep going with that movement until my arm is behind my body, I have now technically done hyperextension of the shoulder joint.
There is a second way that the term hyperextension can be used, which is to describe the condition of hyperextension. This condition can describe the position of multiple different joints in the body, but is probably most commonly applied to the knee joints and the elbow joints.
Hyperextension of the knee joint means that the shape of the joint itself, where the tibia meets the femur, is extended past where we would consider “neutral” to be when we are standing in anatomical position. The chronic condition of hyperextension of the knee joints might have a genetic predisposition as a result of bone shape, and/or laxity of the tendons and ligaments that surround the knee joint. Postural patterns can also influence a habit of moving the knees to hyperextension. An acute condition of knee hyperextension could result from an accident or injury, and is often sports-related.
When to be concerned about hyperextension of the knees
If you experience a chronic pattern of hyperextended knees that is never retrained, it’s possible for problems to occur such as wearing away cartilage, over-stretching the posterior cruciate ligaments of the knee, or overstretching the gastrocnemius and hamstring tendons. If you have an acute condition of knee hyperextension caused by an accident or sports injury, then there may be more immediate injuries that need attention. Concern about a pattern of hyperextension at the knee joints sometimes comes up in activities where we toward ends of range of motion like yoga or gymnastics. But even in those activities the issue is really more of a concern when we're weight-bearing through the knee joint.
What to do?
If you are experiencing the chronic type of mildly hyperextended knees, try cultivating a new pattern. Retrain yourself to maintain a micro bend in the knee joint to keep the surrounding muscles actively holding the knee joint in a healthy place. If you have an acute condition of knee hyperextension caused by a recent accident or sports injury, then you should see an appropriate medical professional for diagnosis and treatment.