6 Most Common Knee Injuries

November 1st, 2022

We may not realize it, but we rely on our knees for more than we think. Whether we’re running, walking up the stairs, or simply keeping our balance as we move from point A to point B, the knee is responsible for a lot of our simple motor functions. And because we rely on it so much, it’s even more likely to fall victim to injury than some of the other joints in our body.

In this piece, we’ll discuss what the knee is made of as well as six of the most common knee injuries our orthopedic specialists see throughout the year.

Anatomy of the Knee

The knee is made up of four components: bones, tendons, ligaments, and cartilage.

Bones: There are three bones that form your knee joint:  the femur (thighbone) and the tibia (shinbone), which meet to form the knee, and the patella (kneecap), which provides protection in the anterior and acts as a lever point for the hinge mechanics of the knee. Injuries to bones are referred to as fractures or breaks and can be very painful. There is often swelling and difficulty with motion as a result.

Tendons: These bands of soft tissue connect the muscle to the bone, both from the front of the thigh to the patella and from the patella to the tibia. Injuries to tendons are referred to as strains, tears, or ruptures. Strains are graded on a scale of I-III and, like fractures, can involve swelling and a lot of pain. A complete tendon rupture can completely “knock out” the function of a joint and make normal movement very difficult.

Ligaments: These are elastic bands of tissue that run from one bone to another, which in turn stabilize the joint itself. In the knee, there are two sets of paired ligaments – collateral ligaments and cruciate ligaments. We’ll discuss injuries to both types in this article. Injuries to ligaments are called sprains. Making up about 42% of all knee injuries, knee sprains happen when multiple fibers in one ligament are overstretched or torn in some way. Sprains are generally graded on a scale of I-III, depending on if there is simply stretching of the ligament, a partial tear of the ligament, or a complete rupture. Pain and swelling are often common after a ligament sprain. Advanced imaging is generally used to confirm the degree of damage.

Cartilage: Found in other joints across the human body, articular cartilage is a soft, slippery padding that lines bony joint surfaces and allows them to slide along one another to bend or straighten without causing injury. Another form of specialized cartilage, the meniscus, or menisci, are two special shock-absorbing pads inside the knee between the thigh bone and the shin bone. The menisci also serve as an important stabilizer for any lateral or twisting movement across the knee. Cartilage injuries can be complex and are often associated with ligament injuries and fractures.

Unfortunately, due to its complex structure involving all these parts, the knee is also one of the most vulnerable joints when it comes to injury. Let’s walk through some of the most common knee injuries, as well as what treatment generally looks like.

[H2] Cruciate Ligament Tears

Your cruciate ligaments are found inside the knee joint and are responsible for the forward and backward stability of your knee. These are your anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), which form an X as they cross one another deep inside the knee.

ACL Tears

The ACL is one of the most pivotal ligaments in the knee, and tears often occur during the course of sports or some athletic activity. Because the ACL is such an important piece of the overall knee structure, an ACL tear tends to cause additional problems. In fact, about 50% of all injuries to the ACL also incur some level of damage to accompanying structures in that same area of the knee.

In most cases, ACL tears happen as a result cutting or moving in an awkward way, usually without any contact at all. Because of this, they normally happen in multidirectional sports like football, basketball, and soccer. Without a functional ACL, the knee can feel very unstable, and normal motion can be significantly compromised, leading to increased risk of falls and other injuries. If someone wants to eventually return to activity where turning, planting, or rotating is required, surgery must be considered for ACL tears.

PCL Tears

Opposite to anterior cruciate ligament, its counterpart, the PCL, is responsible for the posterior stability of the knee. Tears are often the result of contact to the front of the knee while it’s bent with a force in the opposite direction. For this reason, they are also frequently injured from a fall on a flexed knee or by passengers during a car accident who can strike the knee on a dashboard.

PCL tears are generally less serious than ACL tears and, in most cases, are just a partial tear. When the tear is partial, they can typically heal on their own over time with the right treatment plan, and surgery does not necessarily need to be considered.

Collateral Ligament Injuries

Unlike the cruciate ligaments found deep within the knee, your collateral ligaments are found on the outside of your knee joint and are responsible for stabilizing and bracing the knee in side-to-side movements. More specifically, the medial collateral ligament (MCL) is on the inside of the knee, while the lateral collateral ligament (LCL) is on the outside of the knee.

MCL Injuries

If you’re moving on foot and someone runs into the outside of your knee or makes significant contact with it, there can be risk of injury to your MCL. It’s a common injury in sports like football, hockey, and soccer.

When the MCL is damaged, overextending and/or locking your knee becomes a lot easier to do and, if so, can lead to some severe pain. Those dealing with an MCL stretch or tear will usually feel pain on the inside portion of their knee. 

LCL Injuries

Probably the least common ligament injury of the bunch, lateral collateral ligament tears occur as a result of someone running into the inside of your knee or from an awkward landing at the end of a jump or fall. A direct blow to this region of the knee can cause a tear or overextension of the ligament that runs along the outside of your knee, which provides stability to your knee joint while you move.

This sort of injury is frequent in sports like wrestling and soccer due to their high-contact nature. While some of these injuries can heal over time, more severe forms of the injury may require a brace following surgery.

Cartilage Injuries and Meniscus Tears

One interesting fact about cartilage is that when injured, it does not have the ability to heal. Thus, injuries to cartilage can be very difficult to manage and over time, damaged cartilage will continue to break down and lead to arthritis. Direct injury to cartilage (the lining of the bone in the joint) can be associated with the previously mentioned ligament injuries or a direct blow to the knee, similar to a fall or fracture.

Meniscus injuries are also often associated with injuries to other structures, particularly when the knee is unstable or moves in a manner that is not natural. However, the meniscus can be injured in isolation, typically with a pivot or abrupt turn. Damage to the meniscus can cause mechanical symptoms as well; when a piece of damaged cartilage does not sit properly in the knee, it causes significant pain and leads to difficulty bending the knee and walking.

Tendon Injuries

Tendons are what attach our muscles to our bones and make our joints move as we use them. Thus, injury to tendons from falls or contact during sports can be very painful and can compromise our ability to use our joints. 

These types of injuries occur when the tendons in our knees get stretched beyond normal capacity and give way, leading to a muscle that can no longer function appropriately because it is not attached to a bone. These injuries can be very painful and can lead to severe swelling and severe joint dysfunction, resulting in difficulty walking.

Dislocations or Fractures

Though these injuries are different in their treatment and recovery time, both dislocations and fractures of the knee happen in the same way most knee injuries happen: direct contact to the knee during physical activity, a fall, or other trauma. 

Unfortunately, depending on the severity of fracture or area of dislocation, there is a wide range of recovery times. Some fractures and dislocations can be a medical emergency and require immediate stabilization and urgent treatment. Others may require surgical intervention in a different form.

Thinking you may have a knee injury? See an orthopedic specialist.

If you think you might be dealing with one of the injuries we described here, please consider reaching out to our specialized team at Rothman Orthopaedics. Our team of orthopedic physicians and surgeons is one of the most qualified in the country to help you make a proper diagnosis and get you back to doing what you love.

Rothman Orthopaedics is home to world-class orthopedic specialists serving athletes and patients across the country with bone and joint care from some of the best surgeons and physicians in the country. Find out more about Dr. Stephen A. Stache, a non-operative sports medicine physician and Division Chief for Non-Operative Sports Medicine at Rothman Orthopaedics. If you’re interested in making an appointment, feel free to follow the link or call us at 1-800-321-9999.

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