Anterior Cruciate Ligament (ACL) Injuries :: Collateral Ligament Injuries :: Combined Knee Ligament Injuries
Distal Femur (Thighbone) Fractures of the Knee :: Fractures of the Proximal Tibia (Shinbone) :: Growth Plate Fractures :: Meniscus Tears :: Osgood-Schlatter Disease (Knee Pain) :: Patellar (Kneecap) Fractures :: Patellar Dislocation and Instability in Childrens :: Posterior Cruciate Ligament Injuries :: Shin Splints :: Stress Fractures :: Tibia (Shinbone) Shaft Fractures :: Arthritis of the Knee


The knee is the largest joint in the body, and one of the most easily injured. It is made up of four main things: bones, cartilage, ligaments, and tendons. Because of its complexity, your knee is vulnerable to a variety of injuries. Many knee injuries can be successfully treated with simple measures, such as bracing, rehabilitation, and conservative steroid treatments. Other injuries may require surgery to correct. Every year, millions of patient visits are made to doctors’ offices because of common knee injuries such as fractures, dislocations, sprains, and ligament tears.


  • Bones. Three bones meet to form your knee joint: your thighbone (femur), shinbone (tibia), and kneecap (patella).
  • Articular cartilage. The ends of the femur and tibia, and the back of the patella are covered with articular cartilage. This slippery substance helps your knee bones glide smoothly across each other as you bend or straighten your leg.
  • Meniscus. Two wedge-shaped pieces of meniscal cartilage act as "shock absorbers" between your femur and tibia. Different from articular cartilage, the meniscus is tough and rubbery to help cushion and stabilize the joint. When people talk about torn cartilage in the knee, they are usually referring to torn meniscus.
  • Ligaments. Bones are connected to other bones by ligaments. The four main ligaments in your knee act like strong ropes to hold the bones together and keep your knee stable.
    • Collateral Ligaments. These are found on the sides of your knee. The medial collateral ligament is on the inside of your knee, and the lateral collateral ligament is on the outside. They control the sideways motion of your knee and brace it against unusual movement.
    • Cruciate ligaments. These are found inside your knee joint. They cross each other to form an "X" with the anterior cruciate ligament in front and the posterior cruciate ligament in back. The cruciate ligaments control the back and forth motion of your knee.
  • Tendons. Muscles are connected to bones by tendons. The quadriceps tendon connects the muscles in the front of your thigh to your patella. Stretching from your patella to your shinbone is the patellar tendon.


Anterior Cruciate Ligament (ACL) Injuries

One of the most common knee injuries is an anterior cruciate ligament sprain or tear. This injury is common to athletes, particularly those participating in high demand sports like soccer, football, and basketball. This injury may require surgery to regain full function of your knee.

Collateral Ligament Injuries

Your knee ligaments connect your thighbone to your lower leg bones. Knee ligament sprains or tears are a common sports-related injury. Regaining full movement is vital given the knee is the largest joint in your body and one of the most complex.

Combined Knee Ligament Injuries

Because the knee joint relies simply on the collateral and cruciate ligaments and surrounding muscles for its stability, the knee is easily injured. Any direct contact to the knee, or hard muscle contraction, can injury a knee ligament.

Distal Femur (Thighbone) Fractures of the Knee

Fractures of the thighbone that occur just above the knee joint are called distal femur fractures. The distal femur is where the bone flares out like an upside-down funnel. Distal femur fractures most often occur either in elderly people dealing with weak bones, or in younger people who have high energy injuries, such as from a car crash. In both the elderly and the young, the breaks may extend into the knee joint and may shatter the bone into many pieces.

Fractures of the Proximal Tibia (Shinbone)

A fracture, or break, in the shinbone just below the knee is called a proximal tibia fracture. The proximal tibia is the upper portion of the bone where it widens to help form the knee joint. Soft tissues, as well as the bone, may be injured at the time of the fracture. Both the broken bone and any soft-tissue injuries must be treated together. In many cases, surgery is required to restore strength, motion, and stability to the leg, and reduce the risk for arthritis.

Growth Plate Fractures

A child’s bones, still in the process of growing, are subject to a unique injury called a growth plate fracture. Growth plates are areas of cartilage located near the ends of bones. Because they are the last portion of a child’s bones to harden, growth plates are particularly vulnerable to fracture.

Meniscus Tears

Meniscus tears are among the most common knee injuries. Athletes, particularly those who play contact sports, are at risk for meniscus tears. However, anyone at any age can tear a meniscus. When people talk about torn cartilage in the knee, they are usually referring to a torn meniscus.

Osgood-Schlatter Disease (Knee Pain)

Osgood-Schlatter disease most often occurs during growth spurts, when bones, muscles, tendons, and other structures are changing rapidly. Because physical activity puts additional stress on bones and muscles, children who participate in athletics — especially running and jumping sports – are at an increased risk for this condition. However, less active adolescents may also experience this problem. In most cases involving this form of knee pain, simple measures like rest, over-the-counter medication, and stretching and strengthening exercises will relieve pain and allow a return to daily activities.

Patellar (Kneecap) Fractures

Because your kneecap (patella) acts like a shield for your knee joint, it can easily be broken. Falling directly onto your knee, for example, is a common cause of patellar fractures. Patellar fractures vary. The kneecap can crack just slightly, or can be broken into many pieces. Fracture types can include: stable, displaced, comminuted, or open.

Patellar Dislocation and Instability in Children (Unstable Kneecap)

The kneecap (patella) is usually right where it should be in adolescents—resting in a groove at the end of the thighbone (femur). When the knee bends and straightens, the patella moves straight up and down within the groove. Sometimes, the patella slides too far to one side or the other. When this occurs — such as after a hard blow or fall — the patella can completely or partially dislocate. Whether the dislocation is partial or complete, this injury type typically causes pain and loss of function. Even if the patella slips back into place by itself, it will still require treatment to relieve painful symptoms. Children experiencing a dislocation of any kind should be taken to their orthopedic physician for a full examination to identify any damage to the knee joint and surrounding soft tissues.

Posterior Cruciate Ligament Injuries

The posterior cruciate ligament is located in the back of the knee. It is one of several ligaments that connect the femur (thighbone) to the tibia (shinbone). The posterior cruciate ligament keeps the tibia from moving backwards too far. An injury to the posterior cruciate ligament requires a powerful force. A common cause of injury is a bent knee hitting a dashboard in a car accident or a football player falling on a knee that is bent.

Shin Splints

A common exercise-related problem, the term "shin splints" refers to pain along the inner edge of the shinbone (tibia). This injury typically induced by physical activity, is often associated with running. Shin splints can be relieved by simple measures such as resting the body, icing the area, and stretching. The best preventative measure to avoid this injury altogether is avoiding “overdoing” your exercise regimen.

Stress Fractures

Another common overuse injury is the stress fracture. Stress fractures occur when muscles become fatigued and are unable to absorb added shock. Often this occurs when the amount or intensity of an activity has been increased too rapidly. Eventually, the fatigued muscle transfers the overload of stress to the bone causing a tiny crack called a stress fracture.

Tibia (Shinbone) Shaft Fractures

The tibia, or shinbone, is the most common fractured long bone in your body. A tibial shaft fracture occurs along the length of the bone, below the knee and above the ankle, and typically occurs only after a major force. Fracture types may include: stable, displaced, transverse, oblique, spiral, comminuted, open, and closed.

Arthritis of the Knee

Arthritis is inflammation of one or more of your joints. Pain, swelling, and stiffness are the primary symptoms of arthritis. Any joint in the body may be affected by the disease, but it is particularly common in the knee. Knee arthritis can make it hard to do many everyday activities, such as walking or climbing stairs. It is a major cause of lost work time and a serious disability for many people. There are many treatment options available to help manage pain and keep people staying active.