What is Involution, and why does anyone involved in acute injury management need to know?

Involution isn’t a word we come across daily, but it is an essential principle in physiology, particularly with our new understanding of knee injury management. But what does it mean? If we look at the word itself in-volution,it is the antonym of evolution. We know that to evolve is to become something more substantial, more significant or better, so it suggests that to involute would mean to regress, go backward and become nothing or less than we were before. The Oxford Dictionary describes involution in physiology as ‘The shrinkage of an organ in old age or when inactive, e.g., of the uterus after childbirth’. Soft tissue musculoskeletal injuries (ligaments, muscles or tendons) can refer to the state of the tissue after it is damaged, torn or ruptured. In the case of, say, an Achilles rupture being pulled away from the bone, if the torn tendon cannot reattach to the bone after a certain period, the tendon will involute, and the torn stump will curl up and die, resulting in calf muscle function being forever lost unless surgery is performed to reattach.

Best avoided if possible

After any injury, the body desperately wants to heal itself. The critical healing period is 5-20 days post-injury, whether soft tissue or bony. If the body can’t start its normal healing pathway during that period, it will give up, and the soft tissue will involute. Understanding this principle is essential for dealing with acute injuries. If they are managed poorly during the ‘magic healing window’, the injury will not heal and will either last a lifetime, require surgery, or both. The ideal way to prevent involution during this healing window differs for each injury. Many health care professionals are not trained on the wide range of soft tissue injuries and how to avoid involution in each injury. They are taught to put the knee in a long brace that keeps it straight. Unfortunately, if it is an ACL, it is one of the best ways to encourage involution and ruin any chance of healing.

This management will maximise a chance of ACL involution

However, keeping the knee straight for a PCL or PLC injury can assist healing. An experienced healthcare professional with an interest in acute knee injuries can make a preliminary diagnosis of these injuries and put the knee in the ideal position for healing and preventing involution. With the acute knee injuries that we see every day in our ski clinics, we have scoured the planet for the best way to encourage healing and have developed a world-leading acute injury management program for the range of these common traumatic knee injuries (ACL, MCL, PCL, PLC and meniscus tears).

This type of ACL tear may heal

In the world of acute knee injuries and all sports injuries, no injury seems to garner attention and controversy like the anterior cruciate ligament (ACL).  And in ACL tears, there is no higher risk sport than skiing. We have been working closely with leading sports doctor and ACL researcher Tom Cross, who has overseen over 480 ACL tears managed through his “Cross Bracing Protocol” in the Stadium Sports Clinic in Sydney. Tom estimates that about 75% of ACLs injured while skiing are healable. In ball sports with contact, such as football or rugby, the injuries are often high-energy/high-velocity, and the ACL is more profoundly injured and not healable. These high-force ruptures happen in skiing, in very high-speed falls, or landing from big jumps, and large, swollen knees characterise them. After taking an MRI, we see that ligament ends are pulled apart and frayed, and one of the stumps may have flipped over with a significant gap distance (distance between the two torn stumps). These injuries have a poor healing chance and often damage other structures in the knee, contributing to gross swelling and pain.

This type of ACL tear is unlikely to heal

It’s important to note that not all ACL tears can heal, and an MRI read by a person with a special interest in ACL tears is necessary to decide which ones are more likely to heal. While it can be challenging to know if a ligament has involuted, and for people who are unlucky enough to tear their ACL on holidays, it can be difficult to get an MRI until they return home, the main goal should be to reduce the injury to put the injured parts in a close to ideal position, and as best as possibles, prevent involution.