Knee Extension Lag

What Is Knee Extension Lag?

When your leg is in proper working order, you have no difficulty straightening it out completely.

People with the condition called knee extension lag, however, can’t do that. When they try, the knee remains partly bent.

Knee extension lag

The severity of the condition is expressed in degrees. If the patient does his or her best and the knee still has a 20-degree bend, that’s 20 degrees of knee extension lag. If the best a person can manage is a 30-degree bend, that’s 30 degrees of knee extension lag. And so forth.

What’s Happening if You Have a Knee Extension Lag?

When someone stands straight with complete, normal leg extension, the hamstring muscles in the back of the leg and the quadriceps in the front are mostly inactive. If you have knee extension lag, however, the hamstrings are short and the quadriceps muscles are hard at work.

There are a number of underlying reasons why this may be happening. These include the following:

  • Bone spurs
  • A posterior cruciate ligament is too tight or has suffered scarring
  • Damaged, locking meniscus tissue
  • Chronic tightness in the hamstring muscle
  • The joint capsule has been scarred by arthrofibrosis (in other words, after knee arthroscopic surgery)

Why Knee Extension Lag Is A Problem

When in proper working order, the human body should be able to hyper-extend the knee joints and stand for a long while without discomfort, fatigue, or very much consumption of energy.

If you have knee extension lag, though, standing works differently. Because the thigh muscles have to work considerably harder to support your weight, the patellar tendon, quadriceps tendon, and kneecap cartilage are all placed under a strain. If the knee lag extension goes uncorrected, the tendons eventually tear and the back kneecap loses cartilage.

Try this experiment to get a taste of what knee extension lag is like. Stand with your knees slightly bent. It won’t be long at all before you feel strain and discomfort in your thigh muscles.

Knee Extension Lag Treatment

As you might expect, providing knee extension lag treatment starts with diagnosing the source of the problem.

For example, patients wit bone spurs may need them removed.

Similarly, it’s conceivable that the hamstrings themselves are undamaged but the nerves connected to them are making them function improperly, and treatment will center on correcting the problem with the nerves.

Sometimes it turns out that the quadriceps and patellar tendon have suffered significant damage. In those instances, platelet-rich plasma can often turn the damage around, or, in the more severe cases, stem cell therapy injections.