Knee Pain & Injury Information

What is the basic anatomy of the knee?
The knee is the largest joint in the body located between the thigh bone (femur) and shin bone (tibia). The joint is protected in front by the knee cap (patella). Cartilage on the ends of each bone and underneath the knee cap absorbs shock and provides a smooth, gliding surface for joint movement. Ligaments, tendons, and muscles run along the sides and front of the knee connecting the shin bone to the thigh bone at the center of the knee.
How common is knee pain?
Knee pain is very common, especially among athletes. It’s responsible for about one third of all doctor’s visits for muscle and bone pain.
What is involved in a physical examination of the knee?
The doctor will examine the movement of the knee while placing it in a variety of positions and performing in-office tests. He/she will also assess the appearance of the knee and compare it to the “good” knee.
What are some common causes of knee pain?
Some of the most common causes of knee pain are swollen or torn ligaments, cartilage (meniscus) tears, and a condition known as runner’s knee. Some people are more likely to develop knee problems than others depending on their job, participation in certain sports and recreational activities, their age, or physical conditions such as osteoporosis or arthritis.

The two main types of knee injuries are sudden (acute) injuries and overuse injuries.

What are sudden (acute) injuries?
Sudden injuries may be caused by a direct blow to the knee or from abnormal twisting, bending or falling on the knee.
What are the symptoms of sudden injuries?
Pain, bruising, or swelling may be severe and develop within minutes of the injury. The knee or lower leg may feel numb, weak, or cold; tingle; or look pale or blue.
What are some common acute injuries?
Acute injuries include:
  • Sprains, strains, or other injuries to the ligaments and tendons that connect and support the knee cap.
  • A tear in the meniscus, which works to cushion the knee joint.
  • Ligament tears. The medial collateral ligament (MCL) is the most commonly injured ligament of the knee. An anterior cruciate ligament (ACL) injury is also common.
  • Breaks (fractures) of the knee cap, lower portion of the femur, or upper part of the tibia or fibula. Knee fractures are most commonly caused by abnormal force, such as a falling on the knee, a severe twisting motion, severe force that bends the knee, or when the knee forcefully hits an object.
  • Knee cap dislocation, where pieces of bone or tissue from a fracture or dislocation get caught in the joint and interfere with movement. This type of dislocation is most common among 13 to 18 year old girls.
What are overuse injuries?
Overuse injuries occur with repetitive activities or repeated or prolonged pressure on the knee. Activities such as stair climbing, bicycle riding, jogging, or jumping stress the joints and other tissues and can lead to irritation and inflammation.
What are some common overuse injuries?
Some common overuse injuries include:
  • Patellafemoral pain syndrome: Pain in the front of the knee from overuse, injury, excess weight, or problems in the knee cap.
  • Iliotibial band syndrome (IT band syndrome): Irritation and inflammation of the band of fibrous tissue that runs down the outside of the thigh.
  • Bursitis: Inflammation of the small sacs of fluid that cushion and lubricate the knee.
  • Tendinitis/tendinosis: Inflammation or small tears in the tendons.
  • Plica syndrome: Thickening or folding of the knee ligaments
How are knee problems treated?
Treatment for a knee problem or injury may include first aid measures, rest, bracing, physical therapy, medicine, and in some cases surgery. Treatment depends on the location, type, and severity of the injury as well as your age, health condition, and activity level (such as work, sports, or hobbies).
What is runner’s knee?
Runner’s knee isn’t really a condition itself. It’s a term used to describe a collection of several specific disorders, including iliotibial band syndrome (IT band syndrome) and patellafemoral pain syndrome.
Runner’s knee is a common ailment among runners. It can also affect any athlete that participates in activities that require a lot of knee bending such as walking, biking, and jumping. It usually causes aching pain around the knee cap.
What causes runner’s knee?
Overuse, direct trauma to the knee, misalignment of the bones in the leg or knee, problems with the feet or weak thigh muscles can all cause runner’s knee.
What are some symptoms of runner’s knee?
Symptoms of runner’s knee include pain behind or around the knee cap, pain when you bend the knee, or pain that worsens when walking downstairs or downhill. You may also notice swelling, popping or grinding sensations in the knee.
How is runner’s knee diagnosed?
Runner’s knee is diagnosed following a thorough physical exam. You may also need X-rays, MRIs (Magnetic Resonance Imaging), CT (Computed Tomography) scans, and other tests.
What’s the treatment for runner’s knee?
Minor to moderate cases of runner’s knee may heal on their own, or with the aid of physical therapy. Early diagnosis and treatment is important. To speed the healing it is often advisable to rest, ice and elevate the knee. Severe cases of runner’s knee may require surgery.
What is an anterior cruciate ligament (ACL) injury?
The anterior cruciate ligament (ACL) keeps the knee stable. An ACL injury is a tear in one of the knee ligaments that joins the upper leg bone with the lower leg bone. Injuries range from mild, such as a small tear, to severe, such as when the ligament tears completely or when the ligament and part of the bone separate from the rest of the bone.
What causes an ACL injury?
Your ACL can be injured if your knee joint is bent backward, twisted, or bent side to side. An ACL injury often occurs during contact sports, particularly when rapidly change speed or direction while running. They may also occur when landing after a jump or from sudden and forceful impact.
What is chronic ACL deficiency?
If an ACL injury is not treated, it can lead to ACL deficiency and eventually to osteoarthritis. An injured ACL makes it difficult to control knee movement, and the bones are more likely to rub against each other. The abnormal bone movement can damage the tissue (cartilage) that covers the ends of the bones and can trap and tear the pads (menisci) that cushion the knee joints.
What are the symptoms of chronic ACL deficiency?
The most common symptom of chronic ACL deficiency is the knee buckling or giving out, sometimes with pain and swelling.
How is an ACL injury diagnosed?
Your doctor may be able to diagnose an ACL injury by asking questions about your past health and examining your knee. You may need X-rays, which can show damage to the knee bones. An MRI can show damage to ligaments, tendons, muscles, or knee cartilage.
Your doctor can also perform an arthroscopy where he/she inserts surgical tools through one or more small cuts (incisions) in the knee to look at the inside of the knee.
How is an ACL injury treated?
Initial treatment of an acute ACL injury consists of using first aid steps to stabilize your knee and reduce swelling and pain. Move your leg as little as possible, apply ice and use an elastic bandage to give gentle compression to the knee. Also elevate your knee above the level of your heart.
Later treatment may include several months of rehabilitation, or surgery followed by rehabilitation. Not all ACL tears require surgery.
How can you prevent ACL injuries?
The best way to prevent ACL injuries is to stretch and strengthen the leg muscles, especially the front and back muscles of the thigh (quadriceps and hamstrings).