You've Sprained Your MCL - All of Your Questions Answered.

1. What the heck is an MCL and what's its purpose?

MCL stands for medial collateral ligament and as the name implies - it is a ligament.  Ligaments are different from muscles and tendons in many ways, but, with regards to the MCL, its main role is to limit excess motion at the knee, especially when the knee caves in.  

To understand how the MCL works, we must understand the knee joint. The knee joint, which is comprised of the femur and tibia, is very good at moving in a straight line but not so much in other directions. Akin this to a hinge on a door that can swing open or closed but is unable to rotate like a doorknob or bend like a stick would. Ironically, the hip above and ankle below love these types of movements, and the knee, which's stuck in the middle, must adequately adapt to this.

This is where the individualistic nature of ligaments, muscles, and tendons come into play; together they restrict, produce, and transfer forces for safe and efficient movement.

Anatomy dictates function - The MCL, which is divided into superficial and deep sections, spans from the end of the femur to the top of the tibia along the medial side of the knee joint. The superficial part of the MCL is longer, blends with parts of connective tissue that surround the knee cap, and runs parallel with the femur and tibia.

The deep part, on the other hand, is shorter, runs obliquely from the end of the femur to the back side of the tibia, and has more investing attachments to the medial meniscus, posterior joint capsule, and tendon of the semi-membranous muscle (not shown) (1).

From the image above we can see how the MCL would either limit the foot from moving too far outside the body or the knee from collapsing too far inside the foot. This position is called knee valgus, and cadaver studies have shown at 5 and 25 degrees of knee flexion, the MCL provides 57% and 78% restraint of the valgus moment, respectively (2).

In addition to side to side motion, the MCL becomes relatively taut in knee hyperextension (someone who locks out their knees) and at extremes of tibial external rotation (picture someone whose knees face straight ahead but their feet point outward). This is primarily due to the MCL's position along the knee joint. Not surprisingly, the risk of an MCL injury significantly increases when all three happen in conjunction, which is often the case (1)(3)(5).

The MCL is a ligament that restricts excess motion at the knee joint. Its main purpose is to limit knee valgus (knee collapse), knee hyperextension, and extremes of external tibial rotation. Common injury mechanisms include the knee collapsing in while the foot is planted and excessive knee hyperextension.

2. How bad is my injury and how long will it take to recover?

MCL sprains are graded as 1, 2, or 3 and are based on the severity of certain diagnostic criteria. These criteria include the area of tenderness, the amount of joint laxity and if the knee is unstable or not.

*If you are unfamiliar with what sprain means, it's just a fancy word for stretching or tearing of a ligament.

* Valgus stress testing is when a clinician tries to "gap" the inside of the knee joint due to the loss of restraint from the MCL.  

Grade 1 - Localized tenderness, 3 - 5 mm of laxity with valgus stress testing, and no reported instability. Grade 1 sprains are considered relatively minor (2).

Grade 2 - Generalized tenderness, 5 - 10 mm of laxity with valgus stress testing, and no reported instability. Grade 2 sprains are considered more severe but not complete disruption of the MCL complex (2).

Grade 3 - Gross tenderness, greater than 10 mm of laxity with valgus stress testing, and instability of the knee joint. Grade 3 sprains result in complete tearing of the MCL complex and are the most severe (2).

3. How long until I can resume my normal activities?

Healing times are inconsistent in the literature, highly variable, and depend on a multitude of factors. Generally speaking, recovery times for MCL sprains are as follows:

Grade 1 - Roughly 10 days for a return to sport or work-related activities (3).

Grade 2 - Roughly 20 days for a return to sport or work-related activities (3).

Grade 3 - Roughly 4 to 8 weeks, however, this is highly dependent on other compounding variables such as the involvement of the anterior cruciate ligament and medial meniscus (4).

4. Can complete tears (grade 3) of the MCL heal?

In short, yes, grade III tears of the MCL can heal without surgical intervention. Despite a complete disruption of the ligament, the MCL houses a rich blood supply, wide surface area, and optimal location on the knee for regeneration. Secondary structures also provide support to the MCL, essentially "picking up" the slack while the MCL heals (4).

In a 46 month study following 21 collegiate athletes with isolated grade III MCL tears, a success rate of 95% was reported. The average time to full contact conditioning was 9.2 weeks, and all athletes with remaining eligibility returned to their respective sport (4).

Caveats to Grade III tears

1. Isolated grade III tears are the exception to the rule, not the standard. Research has shown a high probability of damage to secondary structures, most commonly, the anterior cruciate ligament (ACL) (5).

2. Criteria for good non-surgical outcomes include no valgus instability or articular irritation and natural alignment of the knee. Examples of articular irritation include entrapment of the MCL inside the knee joint or bony avulsion (5).

5. Should I have surgery?

While success rates are high for non-surgical management, failure to recover appropriately can result in chronic knee instability, secondary anterior cruciate ligament (ACL) dysfunction, weakness, and osteoarthritis.  

If other factors are involved, then surgery might be the best option if:

1. If you have an ACL or posterior medial capsule tear in conjunction with your MCL tear.

2. You have failed non-surgical treatment and instability of your knee remains.

3. There is the presence of a bony avulsion or entrapment of the MCL in the knee joint.

4.  You have a severe valgus alignment of your knee.

According to the research, the most common surgical indications were patients with chronic instability who had failed non-surgical treatment or who had multi-ligament knee injuries (5).  

*As always this should not be considered medical advice and you should consult with your doctor before making any medical decisions.

6. My doctor said the deep portion of my MCL is injured, what does this mean?

Reviewing question number 1, the MCL is divided into superficial and deep sections. Some research and textbooks describe the deeper portions of MCL to be more frequently injured than the superficial fibers during a valgus-related injury. In theory, because the deeper fibers of the MCL are shorter than the superficial fibers, they experience a higher percentage of strain during a valgus load (1).

Possible complications of a deep MCL sprain include an increased presence of rotational instability and increased valgus laxity when the knee is straight (1).

7. Other than surgery, what else can I do?

Rehab of course! The best medicine for a non-surgical MCL sprain is guided exercise. We won't give specifics because every case is different. Look for an excellent physiotherapist. Ask around, do your research and you'll be in good hands. After all, you only get two knees.

If you're the stubborn type and decide to wing it, at least do these three things:

1. Wear a hinged knee brace to limit the possibility of subsequent valgus stress-related injuries.

2. Early motion and weight bearing are encouraged. Don't be afraid to put weight on your leg, within reason of course.

3.  Not to beat a dead horse, but get assessed. You need to rule out any other serious issues before an appropriate rehabilitation program can be prescribed.

8. Will I be able to return to my prior activities?

If you've made it this far, then yes, you should be able to return to all your prior activities. If you've just skimmed this article, scroll back up for more details about recovery times and outcomes.

9. How can the Vital Six help me?

We offer the best and most comprehensive rehab programs on the market. Our goal is to make sure you get back to the activities you love as quickly as possible.

To take the next step, and talk to a physcial therapist today by calling or texting 913 - 303 - 0032. . We know we can help you get back to the life you deserve, and if you give us a chance, we promise we won't let you down.

Citations

1. Neumann, Donald. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. Elsevier, 2010.

2. Musculoskeletal key. Medial Ligamentous Injuries of the Knee: Acute and Chronic. https://musculoskeletalkey.com/medial-ligamentous-injuries-of-the-knee-acute-and-chronic-2/. Accessed January 12, 2019.

3. Encinas-Ullán CA, Rodríguez-Merchán EC. Isolated medial collateral ligament tears: An update on management. EFORT Open Rev. 2018;3(7):398-407. Published 2018 Jul 2. doi:10.1302/2058-5241.3.170035

4. Andrews K, Lu A, Mckean L, Ebraheim N. Review: Medial collateral ligament injuries. J Orthop. 2017;14(4):550-554. Published 2017 Aug 15. doi:10.1016/j.jor.2017.07.017

5. Phisitkul P, James SL, Wolf BR, Amendola A. MCL injuries of the knee: current concepts review. Iowa Orthop J. 2006;26:77-90.

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