Knee pain can be caused by a number of issues such as overuse, arthritis, or injury. Symptoms of knee injury can include pain, swelling, and stiffness.
Common causes of knee pain include:
Damage to the menisci
Sitting between the upper and lower leg bones at the knee joint are rubbery pads of tissue called menisci. These pads cushion the bones, acting as shock absorbers. The menisci can become worn as you get older, and are a common reason for knee pain in middle-aged people. A meniscus can be torn after suddenly twisting the knee joint. A tear of this kind may resolve itself without treatment, although surgery is sometimes needed to repair the injury.
Osteoarthritis
In older people, prolonged knee pain is often caused by osteoarthritis. Osteoarthritis causes damage to the articular cartilage (protective surface of the knee bone) and swelling of the tissues in and around the joint. Osteoarthritis can sometimes affect younger people, especially those who are overweight or have had serious injuries to the knee in the past.
Torn ligament or tendon
Knee pain may be caused by torn ligaments or tendons. Ligaments are tough bands of tissue that connect the bones at the knee joint. Tendons on the other hand connect the muscles to the bone.`
Knee Anatomy
No matter what you do for work or pleasure, standing, sitting, running to the grocery store or running a football, the knee is truly one of the most complex joints of the human body. We will touch on how it moves as well as all of the components which enable it to do all the things we need it to do.
Simply put, the knee works in a similar fashion to a modified hinge on a door. It not only bends back and forth like a hinge, but it also has a complex rotational component that occurs whenever we bend (this is called “flexion”) as well as when we straighten it (this is referred to as “extension”). It is a major weight-bearing joint that is held together by muscles, ligaments and soft tissue. Cartilage can be found inside the joint and provides shock absorption which comes into play whenever we walk, run, lift, climb stairs and pretty much any other impact activity you can name. See the below illustration for more on the components of the knee.
Your knee is comprised of four main components:
Bones
Your knee is made up of the thighbone (femur), the shinbone (tibia) and the kneecap (patella). So how do these bones work together? The thighbone and shinbone come together to form a hinge with the kneecap in front of them, which provides protection for the joint. All the while, the kneecap moves in a sliding action up and down in a groove in the thighbone. This groove is called the femoral groove and the sliding occurs whenever we bend or straighten our knees.
Ligaments
The job of the ligaments is to assure that the components of the knee are held together and kept stable. The medial (inner) collateral ligament (MCL) and lateral (outer) collateral ligament (LCL) limit sideways motion of the knee. All the while, the posterior and anterior cruciate ligaments (PCL and ACL) limit forward motion of the knee bones, thus keeping them stable.
Cartilage
Each knee has two cartilage structures called menisci, which sit between the thighbone and the shinbone. These act as shock absorbers. Oftentimes, a torn meniscus is called “torn cartilage.” The menisci are one of two types of cartilage in the knee. The second type, articular cartilage, is a smooth and very slick material which covers the end of the thighbone, the femoral groove, top of the shinbone and the underside of the kneecap. All of these enable the knee and its bones to move smoothly.
Tendons
The information listed on this site is for informational and educational purposes and is not meant as medical advice. Every patient's case is unique and each patient should follow his or her doctor's specific instructions. Please discuss nutrition, medication and treatment options with your doctor to make sure you are getting the proper care for your particular situation. The information on this site does not replace your doctor's specific instructions.
Knee Arthritis
An estimated 50 million adults in the U.S. have been diagnosed with some form of arthritis, or other disease of the musculoskeletal system. This includes (based on 2005-2007 estimates) 27 million people with OA and 1.5 million people with RA.
Any form of arthritis may cause the knee joint to become stiff, making it difficult to bend or extend the knee, and may cause pain. The two most common forms of Arthritis are Osteoarthritis and Rheumatoid Arthritis.
Osteoarthritis is a slowly progressive degenerative disease in which the joint cartilage gradually wears away or loses flexibility. Without cartilage, the bones have no cushioning to protect them from grinding against each other. With OA, the knee joint may ache, be painful or be stiff first thing in the morning, during and after physical activity, and even after periods of inactivity.[1]
Rheumatoid Arthritis is an inflammatory disease in which the immune system can destroy the joint cartilage. It can cause the soft tissue lining the inside of joints (also called the synovial membrane) to produce too much fluid, causing swelling known as “water on the knee.”[2] RA can occur at any age. With RA, the knee can become swollen, red, and hot to the touch.[3]
Post-traumatic arthritis – another cause of knee problems that is similar to osteoarthritis – can develop after an injury to the knee. This type of arthritis may develop years after a bone fracture, a tear to cartilage called the meniscus, or injury to the two major ligaments that stabilize the knee – the anterior or posterior cruciate ligaments (ACL/PCL).[4]
Knee Injuries
Few parts of the human body are more synonymous with sports injuries than the knee. Namely because the knee joint is instrumental in helping us perform almost every athletic task. Here we will look at some of the most common sports-related injuries to the knee. How they happen. What can be done to prevent them and how to treat them when they do occur.
Meniscus Tear
One of the most common types of knee injuries is what is called a meniscal tear. The menisci are two horseshoe-shaped pieces of cartilage found between the thighbone (femur) and shinbone (tibia.) They act as a rubbery cushion that provides the knee with stability and behave as a shock-absorbing system. Meniscal injuries can happen in a variety of ways and are usually referred to as tears. Those playing sports can tear a meniscus by twisting a knee too hard. Tears can even occur from everyday life movements like stepping off a curb.
Anterior Cruciate Ligament
The anterior cruciate ligament (ACL) stabilizes your knee and connects the thighbone (femur) to the shinbone (tibia.) The ACL is often torn by changing direction too quickly or landing from a jump.
Posterior cruciate ligament
The posterior cruciate ligament (PCL) is located on the back of your knee and connects your thighbone to your shinbone. The PCL can tear when you take a bad fall on a bent knee.
Patellofemoral Joint pain
This type of pain occurs around the front of the knee and is commonly found in athletes who put heavy stress on their knees.
Articular Cartilage Injuries
Arthritis is one of the purest forms of inflammation within the knee joint and is often used to describe wear and tear and loss of the articular cartilage along the gliding surfaces on the knee joint. Injuries to the articular cartilage can occur from rapid deceleration or quick changes in direction during athletic activity.