EN 
NL Stretch limitation after knee surgery
We often see a limitation in knee extension after knee surgery. We can distinguish two reasons by which we can explain why a knee may not be able to stretch after an injury or surgery.
The least common reason is an intra-articular mechanical blockage. This means that there is something in the joint that is preventing the knee from stretching. This is rare because any loose fragments/tissues in the knee are basically removed naturally during surgery. The most important reason for a stretch limitation after surgery is found in the muscles around the knee and their control.
Our body cannot distinguish between injury and surgery and thus cannot know that surgery is being performed with the aim of restoring function and anatomy. So after surgery, the body signals tissue damage, so to speak, which causes it to take protective action. It does this in the case of the knee by switching off the quadriceps (knee extensors), so to speak. What actually happens is that the nerve stimulus sent from the brain to tighten these muscles is blocked. As a result, the stimuli needed to tighten the muscles do not arrive and no muscle contraction occurs. We also call this principle arthrogenic muscle inhibition (AMI). In addition to preventing the quadriceps from contracting, we also regularly see a kind of spasm of the hamstrings, which causes the leg to remain in flexion.
Trochantor major syndrome
Unfortunately, there are still question marks surrounding the concept of AMI. From the scientific point of view, it is thought that the underlying mechanism lies in swelling, pain and restlessness in the knee causing certain receptors to be stimulated. This, in turn, then causes the flexors of the knee (hamstrings) to be over-stimulated and the extensors to be inhibited.
Regaining quality stretching and activation of the quadriceps is one of the most important goals in the first phase of rehabilitation. This is because failure to achieve these goals in the first weeks of your rehabilitation is a predictor of problems such as a cyclops (scar tissue formation) in the knee.
Both post-operatively and pre-operatively, proper stretching has great added value. In fact, studies have shown that patients who undergo knee surgery and have good knee extension (and function) experience less pain and restriction after surgery. In addition, good pre-operative function also reduces the risk of cyclops post-operatively. Read what is important for walking patterns.
