The knee is the largest joint of the body, and is also one of the most commonly injured joints. Bones, cartilage, ligaments, and tendons work together to form your knee joint and allow you to bend your leg. Because of all the moving parts on the knee and the sensitive nature of the joint, it’s very prone to multiple types of injuries.
If you’re experiencing knee pain, it’s likely that you’re suffering from one of the most common knee injuries. We’ll help you understand the makeup of the knee, as well as how to identify the symptoms of a knee injury. However, only your orthopaedic doctor can determine what injury you’re dealing with.
Anatomy of the Knee
Within the knee joint are three bones: the femur (thighbone), the tibia (shin bone), and the patella (kneecap). These three bones meet to form the knee joint. Articular cartilage covers the ends of the femur and the tibia, as well as the back of the patella. The cartilage allows the bones of the knee joint to smoothly glide against one another as you bend or straighten your leg. The meniscus is a tough and rubbery wedge-shaped cartilage located between your femur and tibia. The meniscus cartilage cushions the joint and also acts as a shock-absorber between the femur and tibia bones.
There are four ligaments that connect the bones together and stabilize the knee joint. The medial collateral ligament is located on the inside of the knee, while the lateral ligament is on the outside. These ligaments control your knee joint as it moves sideways and stabilizes it and protects it from any unusual movement that may occur. The cruciate ligaments are within the knee joint and cross over each other to create an “X” shape. The anterior cruciate ligament is in the front of the knee joint and the posterior cruciate ligament is located behind it. These ligaments control the back and forth motion of the knee.
The tendons within your knee connect the muscles to the bones. The quadriceps tendon is located in the front of your thigh and connects those muscles to the patella. The patellar tendon connects your patella to your shinbone.
There are many different types of knee injuries that can occur, since there are several different parts that make up the knee. In some cases, more than one knee structure is affected and also injured. Below are the most common types of injuries.
1. Knee Fracture
Your patella, or your knee cap, protects your knee joints from injuries or further damage. When you fall or collide with an object or a person, your kneecap makes first contact and shields the different parts within your knee joint. This makes the kneecap susceptible to fractures.
Knee fractures are common but they’re also very serious. The knee must be immobilized to allow the bone to heal or sometimes needs surgery for repair.
2. Knee Dislocation
A knee dislocation occurs when the knee bones come out of place. This can happen when there is a large impact to the knee, such as a fall, a collision, or a car accident.
In certain situations, the knee will correct itself. It will feel a little sore, but will function normally. If this doesn’t happen, the only way to recover from a dislocation is to relocate the knee bones back into place. A doctor will strategically adjust the bones back in place in what is usually a quick, fluid motion.
3. Knee Ligament Injury
Ligament injuries are extremely common in sports. They occur when the knee is overextended, or moved in a way it shouldn’t naturally move and the ligaments are unable to support the movement. Because the ligaments serve to keep the knee in place, if they’re forced too much, they aren’t able to do their job and they can stretch or tear.
The most commonly injured ligaments include the cruciate ligaments which make up the X - the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The collateral ligaments - the medial collateral ligament (MCL) and the lateral collateral ligament (LCL) - are also commonly injured.
Although ligament injuries are very common, there are varying degrees to how serious the injury is.
Grade I: In a Grade I ligament injury, the fibers have been slightly overstretched causing a ligament sprain. You won’t notice a lot of bruising, if any, and only minimal swelling. An example of this type of injury is an MCL sprain.
Grade II: This is when the ligament fibers are partially torn, but not all the way across. This will result in more pain and joint restriction than Grade I, as well as additional bruising and swelling.
Grade III: A Grade III injury is when the ligament is completely torn which involves severe pain initially. The knee and surrounding area will be very bruised and swollen. An example of this type of injury is an LCL tear.
4. Meniscus Tear
Meniscus tears occur frequently during sports where jumping or twisting is involved, such as volleyball. Meniscus tears also are common in sports such as football or soccer, where athletes change direction quickly while running. Any type of knee twisting, cutting or pivoting can result in a torn meniscus. Sometimes the meniscus also tears from wearing out over time.
5. Knee Tendon Tear
Tendon tears can happen to anyone, but are especially common in middle-aged people who are running or engaging in jumping sports and other activities. Landing awkwardly after coming down from a jump is a common way to injure the tendon, as the tendon is unable to support the overextension.
Falls can also cause a stretched tendon due to the direct force to the front of the knee.
Knee Injury Signs and Symptoms
Two tell-tale signs of a knee injury are pain and swelling of the knee. You may also have difficulty with the joint moving. It may feel stiff, lock up, or feel like it’s catching as you bend and straighten your leg.
If you hear your knee pop and then give out at the time of impact, it’s definitely a cause for concern. This popping sound could be the sound of something tearing. You may feel like you can’t stand firmly on your leg after a knee injury, since your ligaments are unstable. It may feel like your knee is giving way.
Knee Injury Treatment
If your knee pain is minimal, it’s possible you did not injure it and it’s just feeling a little sore from overexertion. You can typically treat this type of pain with the RICE (rest, ice, compression, elevation) method. If this method works for you and you’re feeling back to normal, you can avoid a doctor visit.
When experiencing a lot of pain, swelling, bruising and instability, it’s important to visit your doctor for treatment. Neglecting the problem could aggravate it, and turn a minor sprain into a tear.
One of the first steps of treating your knee injury is stabilizing the knee. Your doctor will likely recommend a brace to keep your knee joint from moving. This will allow bone fractures to heal properly. You may also be given crutches to prevent you from putting weight onto your injured leg.
Physical therapy will involve a program of several weeks of specific stretches and exercises to restore function of your knee joint. In addition, the exercises will strengthen the muscles surrounding the joint.
You may need surgery to treat your knee injury in certain cases to fully restore its function, when physical therapy and other methods have not proven successful. Some injuries cannot heal on their own, such as a completely torn ligament, and they’ll need to be operated on. Many knee surgeries can be minimally invasive and performed arthroscopically using miniature tools and small incisions. In other cases, your surgeon will need to make a larger incision to repair the injury.
Rothman Orthopaedics has many knee specialists that can help you determine what type of knee injury you’re dealing with and how you can find relief. Don’t wait to see an orthopaedic doctor to avoid further injury.