A quick turn followed by a pop of the knee may be the pinnacle of oh s*** moments. It’s a common occurrence in sporting events but also happens in everyday life.
It’s not always a grave situation—knees make creaky noises all the time and are quite robust— but the dreaded knee sprain does happen to many and is immediately impactful.
Despite the suddenness of the injury, it leaves a prolonged aftermath. Not only painful and limiting, but the biggest struggle is the extended time to heal, and potentially the need for surgery.
In this article, we’ll help explain the knee sprain and guide a path to getting you back into action.
Anatomy Review
A knee sprain is the result of damage to the ligaments of the knee joint. There are several major ligaments, and a few lesser ones, that will be covered shortly.
A ligament is a fibrous tissue that attaches bone to bone. Ligaments are often confused with tendons, but it’s a different part of the anatomy.
If you want a full review of the knee and how everything ties together, check out our Quick Guide to Understanding How the Knee Works. But if you want to get straight to it, let’s focus specifically on the ligaments of the knee.
Understanding the difference between the types of tissue in the knee is important because it helps answer the usual question…
“How long will this take to heal?!!?”
The reason is due to blood flow! In general, the ligaments in our bodies have a poor blood supply. Bone has a great blood supply, the muscle has a great blood supply, but cartilage, tendons, and ligaments do not.
Without quick access to new blood, and therefore healing factors that our body uses to repair, it takes an extended time to heal those strained or sprained tissues.
Sprain vs. Strain vs. Tear
Damage to the ligaments gets classified as either:
A sprain is when we overextend a ligament.
A tear is when we overextend, and the two pieces lose their connection.
(Note- A strain is another common orthopedic injury term, but this occurs when we overextend a tendon or muscle.)
All ligaments have a threshold of strength. Just like a rope has an amount of force that it can withstand when holding two objects together. And just like the rope, if a ligament gets stretched too quickly OR too hard, then it gets damaged.
Each ligament provides a specific restraint to prevent the knee from going too far in one direction. Here are the major ones and usual suspects when it comes to knee sprains:
- Anterior cruciate ligament (ACL) is commonly injured in fields sports, volleyball, gymnastics, and skiing. Typically injuries occur by a hit to the side of the knee, or if there is a twisting motion with hyperextension at the knee.
- Posterior cruciate ligament (PCL) is most commonly injured in what is called the “dashboard” mechanism—when knees are bent to the chest (called hyperflexion) and the shin bone is pushed backward. This happens in a car crash (hence the name) or may also occur by getting tackled while the knee is bent.
- Medial collateral ligament (MCL) commonly injured in field and ice sports. This ligament protects the knee from bending inwards.
- Lateral collateral ligament (LCL) protects the knee from going out and is injured much less than the MCL.
- Medial patellofemoral ligament (MPFL) is a small but mighty ligament that helps to stabilize the knee cap in the groove over the knee. An injury to the MPFL is likely anytime there is a dislocation of the knee cap.
You have other ligaments in the knee, but you’re not as likely to injure them.
Grading Your Sprain
Sprains are graded by the level of injury to the tissue. These grading systems vary for different ligaments in the body, but the most common scale for the knee ligament injuries is I-III (least to worst.)
A grade I sprain occurs due to overstretching. It is considered a “mild” sprain and usually results in minor swelling and stiffness of the knee. Current evidence shows that a grade I sprain in the knee will heal and return to normal in anywhere from 4-8 weeks.
It’s a frustratingly long time for some “minor” stretching. But the blood supply issue pushes the healing time out longer than most people suspect. And since the knee is so crucial to getting around, even minor discomfort doesn’t go unnoticed.
A Grade II sprain means there is a small tear, but it’s not all the way through the ligament. At this time, it’s unknown how much those sprains truly heal, but it’s safe to assume that you can get back to your sport after some time off.
A Grade III sprain is equivalent to a full tear in which the ligament has torn apart from itself and don’t expect these to heal. Grade III sprains often undergo surgery, although there are currently many valid non-operative options.
Diagnosing Your Knee Sprain
If you’ve been hit with a knee sprain, start by looking for the following Red Flags as a reason to seek further medical evaluation.
Medical Red Flags
- Knee gets “locked” in position- either bent or straight
- New onset of painful clicking or catching
- Feeling of instability or giving out
- Swelling that lasts >5 days
If you test out of all these and want to save the time and money, then it’s fine to wait it out.
But, if you’re worried about your knee, get it checked out by a medical professional for peace of mind. It’s not really an emergency situation though, so no need to rush to the emergency room.
If you have direct access to a physical therapist in your state, this is probably your best resource for the sake of time, cost, and a more comprehensive recovery plan when appropriate. Otherwise, a general practitioner or urgent care clinic can evaluate the issue and provide further recommendations, which are usually rest and anti-inflammatories, and potentially a referral for a sports medicine doctor (ref).
The Process for Knee Sprain Rehab
If you’ve sprained your knee, the first question is likely: What should be done? It’s a simple, yet challenging task, and that is resting the injury.
Rest will be slightly different for each type of sprain, but in general, it means eliminating painful activities. In the best-case scenario, inflammation takes about 14 days to resolve. Thus, the rule of “if it hurts, don’t do it” is a safe bet to follow for 2 weeks. Trying to push through the pain will only bring further inflammation and ultimately slow healing time.
In total, you’re looking at a healing time of 6-8 weeks, but will be feeling better between 2-4 weeks. You will notice a reduction in swelling, and your range of motion will return to normal. You’ll feel that it’s time to get back to life—unfortunately, it’s not done healing.
It’s in the window of weeks 2-4 that people run into issues because they jump right back into their previous activity level. Even though the knee feels better, it’s still missing some stability, which increases the risk of hurting the same ligament again. If not something worse!
It’s during these weeks that a properly structured exercise plan becomes super important.
Low impact exercises targeting the glutes, core, and leg muscles will keep those muscles engaged, while healing occurs. This makes it easier to return to full activity, and potentially even solving some of the underlying strength issues that caused the knee sprain to happen.
If you need help with this, we walk you through everything in our 30-Day Knee Fix.