Your knees do a lot of moving and have a lot of moving parts. So when injuries happen, they can lead to pain, weakness in the joint and limited activity. In fact, knee pain is the second most common cause of chronic pain among American adults, and a third of all Americans have reported having knee pain at some point in life.
The Knee Joint: The Basics
As the largest joint in the body, the knee is one of the most easily injured. It’s composed of bones, ligaments, tendons and cartilage.
- Bones: The kneecap (patella), shinbone (tibia) and thighbone (femur) meet to form the knee joint.
- Ligaments: Four main ligaments in the knee, the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL), hold the bones together and provide stability.
- Tendons: Your muscles are connected to your bones by tendons; for example, the muscles in your thigh are connected to the kneecap with the quadriceps tendon.
- Cartilage: The cartilage cushions the bones of the knee joint, protecting the bones and allowing the ligaments to slide over the bones.
Risk Factors for Knee Injury
There are many different factors that can increase your risk of a knee injury, including:
- Sports: high-impact sports, including cycling, running, basketball, soccer, football and others, can increase the risk of knee injury and pain.
- Overuse: during sports and other activities, if you are overusing and overtraining your knee, or training incorrectly, you can increase your risk of a knee injury.
- Disease: Osteoporosis, arthritis, degenerative joint disease, or gout can all cause knee injuries such as bursitis.
- Age: The elderly are at higher risk of knee injury due to falls and diseases like osteoporosis.
- Gender: Women may be more susceptible to ACL and patellar injuries due to their anatomy.
- Weight: Excess weight puts additional strain on lower extremity joints; being overweight can create a greater risk of a knee injury.
Symptoms of Knee Injury
If you experience any of the following symptoms, you most likely have one of the common knee injuries — or another injury — listed later in this article:
- Difficulty bearing weight
- Clicking or popping noises
- Trouble bending the knee
These symptoms can differ depending on the type of injury. For example, acute injuries may cause more pain and swelling, while a chronic injury or injury from overuse may cause intermittent pain, clicking and popping.
Most common knee injuries
Knee injuries are often due to twisting or bending the knee in a way that it was not intended to move, or other behaviors that cause extra force to be applied to the knee, such as falling and other accidents. Here’s a look at some of the most common knee injuries, how they’re caused and treatment options.
1. Torn Meniscus
The knee has two menisci, which are pieces of cartilage that act like pillows between the shinbone and the thigh bone. An extreme twisting motion to the knee can cause one or both of them to tear. Like a torn ACL, a meniscus injury can include a popping sensation, swelling, stiffness and pain. It also can lead to difficulty rotating the knee, extending it, or feeling like it’s locked in place.
2. ACL (Anterior Cruciate Ligament) Injury
This common knee injury happens when the ACL is either sprained or torn. It happens most often while playing sports that have sudden starts, stops, and movement changes, such as football or soccer. If you injure your ACL, you might feel — or even hear — a popping sound. It can also cause immediate swelling, instability and a lot of pain.
3. Patellar Tendonitis
The patellar tendon attaches the quadriceps (thigh) muscle to the shinbone, and activities like running, skiing, cycling, and jumping can cause it to become inflamed and irritated. Also known as Jumper’s Knee, this type of tendinitis will cause pain on the top of the knee that may get worse with jumping, landing, running or even prolonged sitting. A related injury, called Runner’s Knee, can also affect the patellar area.
If you fracture your knee, it’s most likely to be the patella that’s broken. However, the ends of both the thigh bone and shinbone can break as well. A break in the knee area is usually due to a trauma at high force, like a fall or car accident. If you think you may have broken your knee, look for swelling, immobility and intense pain.
Your knees contain small sacs of fluid called bursae that act like a cushion on the outside of your knee joint. Their job is to help the tendons and ligaments move smoothly, but they can become filled with blood after injury or overuse, and possibly even infected in rare instances. With bursitis, you’ll likely experience localized swelling, redness, tenderness and warmth that can get worse when you kneel.
When To See a Doctor
You should see a doctor if:
- The knee pain is severe
- The knee pain is chronic
- The knee pain lasts for more than one week
- There is reduced range of motion in the knee joint
- Bending the knee becomes difficult
And, of course, you should immediately see a doctor in cases of blunt force or trauma.
Treatments for Knee Injuries
With the exception of an obvious fracture or severe tear that requires knee surgery, knee injuries are often treated conservatively first with rest, compression, elevation, or anti-inflammatory medications. If those don’t provide enough pain relief or progress, you may be a candidate for knee arthroscopy, a minimally invasive procedure that uses a camera to repair the injury. If knee problems become chronic, you may consider a total knee replacement.
No matter your injury or course of treatment, the experts at Alexander Orthopaedics can help. If your knee has been bothering you, schedule an appointment today.