Stages of Tissue Healing

If you have ever injured yourself, you may understand that there are different stages int he healing process, especially if you ever had to deal with setbacks and re-injury. Furthermore, you may have wondered why the doctor or physiotherapist either limited you or pushed you to do certain exercises at certain times. Understanding the healing process in general can actually facilitate your recovery, as you may have a better idea of why certain advice has been given to you, and you may also be able to better identify when you need to be cautious and when you're good to go.

In this article, we will describe the healing process in general, and we will relate this information to some common injuries that you may have heard about before, or potentially even experienced yourself.

3 Main Stages of Healing

There are three main stages to the healing process. We will break down each of these stages in more detail, and will also provide some analogies for better understanding. One thing to keep in mind with all of this is that tissue and their associated cells basically have a limit as to how fast they can heal. The best thing we can do as patients and healthcare professionals is to provide the best environment possible for healing to take place, so as to not prolong the process more than necessary.

Inflammation Phase

Typical Timeline: 0-10 days

This is a word that many people have heard before, but it's often a misunderstood concept. Inflammation is the very earliest stage of the healing process and is often closely associated with pain and swelling. Of course, pain and swelling are undesirable effects, which is why a lot of pain medication falls under the category of "anti-inflammatory", for example, Advil, Motrin, etc. 

That said, even though the inflammation process often hurts and leads to swelling, we do not want to avoid it altogether. The inflammation process is crucial for proper healing and sets the stage for further work to be done. Generally speaking, inflammation allows the damaged area to be cleaned of toxins and debris that are byproducts of injury to the cells in the area. Increased blood flow to the area will facilitate this process, as increased blood flow will lead to increased nutrition coming into the injured area and more debris and toxins being swept away. 

It is important to note that, at this time, the injured area is extremely vulnerable and fragile, so we need to do all we can to protect it and let the body do its thing. Here are some ways that you can help yourself feel better when an injured region is inflammed, while also provided a good environment for healing.

What To Do During the Inflammation Stage

At this point, the most crucial thing is that you protect your injury. For example, if you recently sprained your ankle, you don't want to put too much weight on it, and you definitely don't want to do strenuous stretching or strengthening of the muscles and other tissue in the area. It may be helpful to wrap it, add some padding to the area, use an ankle brace, or whatever helps you further avoid stressing that area.

Ice can really help with the swelling, and can also provide some pain relief in certain situations. When icing an area, it's important to make sure you have proper sensation, adequate circulation, and no major conditions that can be affected by applying ice, for example, Reynaud's disease. Most ice protocols call for a damp towel to be placed between the ice pack and the skin. This will allow heat to be transferred away from the injured area effectively, while also adding as a safety mechanism so you don't get frost bite or ice burn. It is very important to continually check the area you are icing, as numbing occurs over time, and you may not feel damage like frost bite occurring. Compression can also helps sometimes, as long as there isn't too much pressure on the area. 

In terms of exercise, your doctor or physiotherapist will be able to tell you exactly when to begin certain exercises, and when to hold off. Often times, patients can begin doing active range of motion exercises a few days after injury. This is more so for soft tissue injuries like ligament sprains, and tendon/muscle strains. For example, if you sprained your ankle, some patients may be able to begin moving the ankle around under their own power within tolerable limits. Maintaining motion will prevent it from stiffening up too much, and actually will be a form of mild stretching and strengthening. This is often done in a non-weight-bearing fashion. Fractures are usually treated way more conservatively, so this active range of motion strategy likely won't apply to fractures.

Inflammation Stage Analogy

The following is an analogy I have used to describe the stages of healing before. I hope it makes sense!

Let's say we describe an acute injury in terms of someone's house burning down (weird, I know, but stay with me). If the acute injury is analogous to a house burning down, the inflammation stage can be considered the immediate clean up. The first responders come in to put out the fire and sort through some of the mess. In the days thereafter, the property continues to be cleaned, with all of the old damaged rubble being removed and new material for a rebuild coming in fresh. We now have set the stage for a new framework to be laid down.

Proliferative Phase

Typical Timeline: 7-21 days.

As the inflammatory phase starts to wind down, we begin to enter the proliferative phase. There is always a little bit of overlap between the inflammatory and proliferative phases of healing. For example, you will notice the typical timeline I have listed for inflammation is 0-10 days, whereas the typical timeline for the proliferative phase is 7-21 days, so there is a little bit of overlap here (days 7-10). Also, keep in mind that these timeframes are approximate and generalized, so may vary between individuals with a strong dependency on the nature of injury.

So what is the proliferative phase? The word "proliferative" means to grow or produce by multiplication of parts. When it comes to the human body, this terms is typically used in relation to cellular activity. So in our case of tissue healing, the proliferative phase represents the time when new cells are growing and multiplying, which allows for brand new tissue to be laid down. One thing to keep in mind here is that the new tissue isn't at full strength yet, but rather, has been deposited at the necessary site and is still quite fresh and fragile. 

Unlike the inflammation stage, you shouldn't experience as much pain or swelling, but you may still notice some discomfort, stiffness, and/or weakness. You may still notice pain with excessive force or movement, such as bearing your own weight fully, or moving the injured joint to into its end ranges.

What To Do During the Proliferative Stage

Essentially, you want to build on what you were able to do during the inflammation phase. Remember, there isn't too much you can do in the way of exercise during the inflammation phase, so we are usually limited to simply moving the joint around within tolerable limits. During the proliferative phase, we will gradually move towards applying some load (e.g. partial weight bearing or light resistance) while moving the associated joints around in a very controlled manner.

The exact degree to which you stress the tissue will depend on the nature of the tissue. For example, if you have a ligament sprain, you generally don't want to stretch that ligament. Ligaments are passive structures and can be thought of as strong elastic bands. When a force is applied to a joint that causes a ligament crossing that joint to be stretched, this can lead to damage if the force is too high or rapid. For example, hyperextension of the knee can often lead to ACL tears if that force is too much to handle or it is applied extremely quickly. When we rehab a torn ligament, we don't want to stretch that ligament anymore, which in the case of an ACL, is often why you will see people wearing an ACL brace in the immediate stages after injury or surgery (they are protecting that ligament while still being able to keep the rest of the knee moving around). 

However, since the joint that ligament crosses will now be less stable, we generally tend to work on strengthening other structures around the joint, mainly muscles, too help with stability and provide an optimal environment for the ligament to heal. We may move the ligament around a bit, which can be ok in certain situations, as long as we aren't stretching it too much. You can also work on muscle strength using isometric contractions, which is basically holding a contraction without actually moving. 

Every type of tissue, such as muscles, tendons, ligaments, nerves, bone, etc, all respond differently to mechanical stress, so they all have different requirements in this proliferative stage, which again is why it is important to seek one-on-one in-person advise. From an overall perspective, this proliferative stage will involve a bit more active rehab than the inflammation stage, but we are still cautious to not cause any aggravation of the injured tissue.

Proliferative Stage Analogy

We described the inflammation stage as a burning house under the attention of first responders, who would put out the fire, with the area being subsequently cleaned for future repairs. In the proliferative stage, imagine the exact same property a little bit later. We may see piles of freshly cut building material around, and maybe the foundation or the frame to the house is in place. At this point, the house hasn't yet taken on a true identity, but all the material required for building a solid structure is there somewhere.

In the body, the proliferative stage represents the time when things have started to clear up and new tissue is being laid down at the site of the injury. However, at this point, the new tissue isn't really arranged in a manner that is optimal for the stresses that will be placed on it. We want to continue the process of new tissue being laid down, but we also want to start encouraging it to gain some strength, a process that can be refined in the third and final stage.

Remodelling Phase

Typical Timeline: 14 days to 1+ year

The proliferative phase will eventually blend into the remodelling phase, until we reach the point where we are all in on the remodelling phase. The remodelling phase represents the latest stage of healing, whereby there is no inflammation and we have almost all the new tissue we need to return to normal function.

This stage is where the rehabilitation can become very creative, and actually sometimes fun, and certainly more specific to the patient's exact needs and typical function. Let's take the example of a torn tendon. Once the tendon has healed, the region that was injured will have all the new fibers it needs, but they aren't really organized in the best way. You can picture them as being jumbled around, or mat-like.

In this case, we will likely work on putting some tension on that tissue, either through an isometric contraction or eccentric contractions, or both. An eccentric contraction is when the tissue is contracting, but it's being lengthened at the same time. For example, a biceps curl is a concentric contraction, which means it's shortening while being contracted. As you slowly lower the weight back down, you are still using your biceps just as much (if not more), but the muscle is being lengthened at this point, representing an eccentric contraction. If the biceps tendon was the structure we wanted to fix, the eccentric contraction would help the fibers reorganize themselves in the direction of that pull, making the tendon stronger and more functional for that type of elbow flexion movement.

Physiotherapists will often get creative with the person's occupation, hobbies, or general lifestyle as well. For example, if you have a shoulder injury, but work doing lots of overhead work, they will eventually get you doing exercises that will help the structures in those overhead positions. Another example is if you do repetitive work on a factory line. The rehab will likely, at some point, place a focus on strengthening those sorts of movements to make the work more comfortable, and to also prevent any future occurrences of injury from the workplace.

What To Do During the Remodelling Phase

This is truly aa difficult question to answer, as it's simply too general. It will depend highly on the person, the exact injury, what tissue is damage, how far along in rehab you are, and all sorts of other things like resources and potentially even your financial situation. However, if one thing holds true, it's that we are generally applying more stress to the tissue during this stage, and it really can be considered the final stage of healing, unless you consider general maintenance afterwards as a stage as well. 

For more information on how the remodelling phase works, we suggest you explore the web for information on Wolff's Law, or something called Specific Adaptations to Imposed Demand, a.k.a. the "SAID Principle". These concepts go into way more detail about how human tissue can respond to its environment and the stresses placed on it in order to optimize its own strength and function.

Remodelling Phase Analogy

In the proliferative phase, we had a new foundation and frame to our house, with piles of other building material around the property ready for use. Now in the remodeling phase, we take all the extra details into account. This includes accounting for any stresses the house could be subject to. For example, if it's in the Pacific Northwest, we may opt to build the roof in a manner that will ensure no collection of water, and we will place a lot of focus on ensuring no leaks throughout the house.

As another example, let's say the house is in Chicago, and the street funnels the wind to hit a certain side of the house all the time. We may place or design the house such that it is a little more resistant or aerodynamic to the wind, making it stronger for that specific purpose. Of course, we also have the finishing touches, where we really get to determine what we want in the house, and how much we really want to make it unique to the homeowners.

Conclusion

We recognize this article was a little heavy on content that included physiology and some technical jargon, but we really hope that it gives you a better idea of how the body heals, why timelines are so hard to predict, and what to generally expect with injury recovery. We encourage you to consider this information when researching about how to deal with certain injuries, but again, remember there are professionals out there who are extremely well versed in the ins-and-outs of all sorts of injuries, and they should be consulted whenever possible.

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