The knee is a complicated joint which is made up of muscle, tendons, ligaments, and bones. These components permit it to move in a number of directions enabling us to sit, stand, walk, climb stairs, and change direction (pivot). There are three bones: the femur (thigh bone), the tibia (shin bone), and the patella (knee cap). The surface of the ends of these bones is covered in cartilage. A cartilage pad, called the meniscus, sits between the femur and the tibia. The entire joint is bathed in a slippery fluid – synovial fluid – which lubricates the joint and also supplies the cartilage with nutrients.
Your knees aborb a tremendous amount of energy and power every day. They act as the primary shock absorber in your body. For example, when walking up steps, your knees absorb five to seven times your body weight.
How a Healthy Knee Works
The knee is the largest joint in the body and is central to nearly every routine activity. A joint is formed by two or more bones that are connected by thick bands of tissue called ligaments. The knee is made up of three main parts:
- The lower end of the thighbone, or femur
- The upper end of the shinbone, or tibia
- The kneecap, or patella
The thighbone (femur) turns on the upper end of the shinbone (tibia), and the kneecap (patella) slides in a groove on the end of the thighbone. Ligaments, which are bands of tissue, connect the thighbone and the shinbone to help keep the knee joint steady. The quadriceps, the long muscles on the front of the thigh, help strengthen the knee.
A smooth substance called articular cartilage covers the surface of the bones where they touch each other within the joint. This articular cartilage acts as a cushion between the bones. The rest of the knee joint surfaces are covered by a thin, smooth tissue liner called the synovial membrane, which makes a small amount of fluid. This fluid acts as a lubricant so that the joint bones will not rub against each other.
Common symptoms include instability when standing, walking, or running; stiffness, swelling; a limp when walking.
Injuries to the knee often involve the ligaments that connect or pad the knee. Acute injuries to the knee frequently occur in activities that require acceleration, deceleration, twisting, pivoting, cutting, and jumping.
One of the most common injuries involve the Anterior Cruciate Ligament, which connects the femur and the tibia in the center of your knee. A direct blow to the knee, or sudden stop or landing on an extended leg can result in an ACL tear with symptoms such as an audible popping sound and the knee giving way. See:ACL Tear for more information on this type of injury.
Another common injury involves the Meniscus which absorbs shock between your bones. You can idenitfy it as the pad of cartiledge on the head of the tibia (shin bone). Injuries to the Meniscus often occur as a result of a sudden twist.
Arthritis is the most common form of pain due to general wear and tear. The pain associated with arthritis of the knee usually develops slowly over time, although sudden onset is also possible. Pain may worsen after a period of inactivity, or in the morning. Activities such as walking or kneeling may exacerbate the pain. The knee may become swollen and stiff, and it may become difficult to straighten or bend the knee. The degree of pain and immobility may be affected by changes in the weather.
In most cases, your ProSports physician will be able to diagnose your problem with direct examination. In the likelihood that there may be additional injury to the joint, or if the swelling makes diagnosis difficult, your physician may conduct an MRI or arthroscopy to fully evaluate the injury to the knee.
Surgery or not?
The decision whether or not to surgically repair the knee depends on several factors, including the extent of the injury and the expectations of the patient. Your ProSports physician will determine the degree of the injury or injuries to the knee, and the “laxity,” or looseness, of the joint.
Conservative treatments, such as steroidal and non-steroidal anti-inflammatory drugs, physical therapy, bracing, and cortisone injections may effectively relieve pain and restore mobility for some patients, for some period of time. But more severe conditions may not respond adequately to these approaches. In these cases, the orthopaedic surgeon may recommend knee replacement surgery.
For younger patients with moderate to several injuries and laxity, who want to continue with a broad range of physical activities, surgery will most likely be necessary. For older patients and others with less severe injuries, who anticipate less vigorous physical activity, a rehabilitation program will be prescribed.
Knee rehabilitation includes exercises to restore the full range of motion to the knee, followed by a program of strengthening exercises. These programs continue until the leg strength and flexibility are nearly back to normal.
Protocols are available to guide you through your recovery.
- ACL Protocol
- Arthroscopy Protocol