Knee

Anterior cruciate ligament (ACL)
The ACL is one of the four main ligaments within the knee that connect the femur to the tibia. The ACL runs diagonally in the middle of the knee, preventing the tibia from sliding out in front of the femur as well as providing rotational stability to the knee.

Cause:
ACL injuries happen to active people, especially athletes. Injury is often associated with deceleration coupled with cutting, pivoting or sidestepping maneuvers, awkward landings or "out of control" play. Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes. Approximately 50 percent of ACL injuries occur in combination with damage to the meniscus, articular cartilage, or other ligaments. Additionally, patients may have bone bruises beneath the cartilage surface. These may be seen on an MRI and may indicate injury to the overlying articular cartilage.

Prevention:
Neuromuscular training enhances balance, body/joint awareness, and movement technique, and muscle strength. Good flexibility of the joints, muscles, and tendons, as well as appropriate muscle strength in the lower extremity is important to prevent an ACL injury. “Core strength,” which is strengthening the muscles around the back and hip, is also helpful. Proprioception involves balance and body/joint awareness and can be trained as well. Bracing is rarely needed for sports unless an individual has had a previous injury.

Treatment:
In non-operative treatment, progressive physical therapy and rehabilitation can restore the knee to a condition close to its pre-injury state, while educating the patient on how to prevent instability. A hinged knee brace may be used. Surgical treatment is usually advised for combined injuries (ACL tears in combination with other injuries in the knee). Patients treated with surgical reconstruction of the ACL have a high success rate of restoring stability and function.

In surgery, the ACL is reconstructed, not repaired. That means a tendon is used to make a new ligament as the torn ligament usually is torn in such a way that it cannot be sutured or repaired. There are various tendons that can be used to make the new ACL.

Therapy and appropriate rehabilitation is important following ACL surgery. Any individual undergoing ACL surgery needs to plan rehabilitative exercises for six months to a year.

Meniscus tears
One of the most commonly injured parts of the knee, the meniscus is a wedge-like rubbery cushion (like gristle) where the major bones of the leg connect. Meniscal cartilage curves like the letter "C" at the inside and outside of each knee. A strong stabilizing tissue, the meniscus helps the knee joint carry weight, glide and turn in many directions. It also keeps the femur (thighbone) and tibia (shinbone) from grinding against each other.

Cause:
Athletes in contact sports may tear the meniscus by twisting the knee, pivoting, cutting or decelerating. In athletes, meniscal tears often happen in combination with other injuries such as a torn ACL. Older people can injure the meniscus without any trauma as the cartilage weakens and wears thin over time, setting the stage for a degenerative tear.

Prevention:
Although prevention is important, sometimes these injuries are not preventable. Always warm up. Keep muscles around the knee in good shape through regular stretching and strengthening.

Treatment:
Initial treatment follows the basic RICE formula: rest, ice, compression, and elevation, along with nonsteroidal anti-inflammatory medications for pain. If the knee is stable and does not lock, this conservative treatment may be all that is needed. Blood vessels feed the outer edges of the meniscus, giving that part the potential to heal on its own. Small tears on the outer edges often heal themselves with rest.

If the meniscal tear does not heal on its own and the knee continues to be painful or if there is continued swelling or mechanical symptoms such as catching or locking, then it may require surgical treatment. Depending upon the type of tear, whether there’s also an injured ligament, the person’s age and other factors, a doctor may use an arthroscope to trim off damaged pieces of cartilage. Occasionally, if it is a very specific type of tear, the meniscus can be repaired with a suture. Rehabilitation exercises are important for resuming activity.

Runner’s knee (Patellofemoral Pain)
Various athletes – runners, jumpers, skiers, cyclists, and soccer players – put heavy stress on their knees. "Runner's knee" refers to various medical conditions that can cause pain around the front of the knee (patellofemoral pain). These conditions include anterior knee pain syndrome, patellofemoral malalignment, chondromalacia patella (cartilage damage to the undersurface of the patella), patellar tendinosis, Osgood-Schlatter Disease (apophysitis or inflammation to the bone where the patellar tendon attaches), and some other conditions. Pain is worsened by excessive activity. People often feel stiffness after prolonged sitting.

Cause:
The quadriceps muscles are the largest muscles in the body. A significant force is placed across the knee through the kneecap or patella and the patellar tendon, which attaches to the tibia. A number of factors can contribute to "runner's knee," including: malalignment of the kneecap which can be identified with radiographs and clinical exam, an injury to the knee, excessive training or overuse, inappropriate athletic equipment, especially shoes, or malalignment of the feet and ankles.

Prevention:
To avoid knee pain:
• If overweight, lose weight to avoid stress on the knees.
• Do a 5-minute warm-up followed by stretching before starting exercise. Also stretch after exercise.
• Increase training gradually. Avoid sudden changes in the intensity of exercise. Increase force or duration of activities gradually.
• Use proper running gear, including shoes with good shock absorption and quality construction. Shoe inserts may be necessary for people with flat feet or an excessive arch.
• Use proper running form. Lean forward and keep the knees bent. Never run straight down a steep hill. Walk down it, or run in a zigzag pattern.

Treatment:
Treatment is usually nonsurgical. First rest the knee until pain and swelling go down. Then gradually regain full range of motion. An orthopedist may prescribe an exercise program. Taping the kneecap or using a special brace for knee support during sports may be required. Special shoe inserts (orthotics) may sometimes be prescribed to help the pain go away.

When needed, surgical treatments include:
• Arthroscopy: Arthroscopy can be useful for treating damage to the cartilage surface of the kneecap or moving inflamed tissue in the knee such as a plica and also examining the remaining structures inside the knee.
• Realignment: Realignment of the kneecap may be needed if this is the primary cause of pain.

Patellofemoral instability
The kneecap or patella tracks any groove on the front part of the femur. Some people are prone to have instability of the kneecap because of the anatomical shape of the kneecap or the groove. The kneecap may slide out of place called a subluxation or may come completely out of place and become locked called a dislocation.

Cause:
The patella often sublux or dislocates with a twist to the knee with a foot planted.

Prevention:
It is very important to maintain good quadricep muscle tone as well as good flexibility to prevent this injury. If someone is prone to this injury, bracing may be needed.

Treatment:
If this is a recurrent problem, there are surgical techniques to realign the kneecap. Following surgery, additional strength and rehabilitation would be needed and even possible additional bracing.

Articular cartilage injury
The gliding surfaces of the bone in the knee joint are covered by cartilage. This cartilage is often called hyaline cartilage, articular cartilage or weight-bearing cartilage. It covers the undersurface of the kneecap as well as the entire end of the femur (thigh bone), and the top of the tibia (shin bone). Damage to this cartilage can lead to arthritis.

Cause:
Often the cause of an injury to the articular cartilage is unknown. It can occur with an athletic injury or other type of accident. There is significant variability in the severity of the injury to the articular cartilage. It can get a simple crack or fissure and wear over time due to overuse, or have more significant injury to the cartilage with trauma. This cartilage is several millimeters thick and can be injured down to the underlying bone. Some people may be prone to an injured articular cartilage because of genetics.

Prevention:
The best prevention is to avoid a serious injury to the knee. Similar to the meniscus injury, keep the muscles around the knee in good shape, do regular stretching and strengthening.

Treatment:
These injuries may or may not be seen with MRI scan. Arthroscopy may or may not be needed to treat the lesion. Occasionally small injuries may be treated with chondroplasty, which is smoothing the rough area of the injury. This may not make the knee normal but will help prevent further damage to the cartilage surface. This type of injury is often permanent. If there is an injury of this cartilage all the way down to the bone, there are techniques to restore a cartilage surface, such as microfracture or cartilage transplant. Cartilage grafting is possible for some knees with limited or contained cartilage loss from trauma or arthritis. Visco supplementation, a series of injections into the knee, can help lubricate the knee.

Arthritis of the knee
Three basic types of arthritis may affect the knee joint.
• Osteoarthritis (OA), the most common form of knee arthritis, progresses slowly as the joint cartilage gradually wears away. It most often affects middle-aged and older people. The knee joint is one of the common joints affected by osteoarthritis. Other joints in the body may or may not be affected.
• Rheumatoid arthritis (RA), an inflammatory type of arthritis, destroys the joint cartilage. RA can occur at any age and often affects both knees and can affect other joints in the body.
• Post-traumatic arthritis can develop after an injury to the knee. Similar to osteoarthritis, it may develop years after a fracture, ligament injury, meniscus tear, or articular cartilage injury.

Cause:
Generally, the pain associated with arthritis develops gradually, although sudden onset happens. In fact the pain can have a sudden onset despite the fact that the arthritis has been developing over a significant period of time. The joint becomes stiff and swollen, making it difficult to bend or straighten the knee. Pain and swelling are worse in the morning or after a period of inactivity. Pain may also increase after activities such as walking, stair climbing or kneeling. The pain may often cause a feeling of weakness in the knee, resulting in a "locking" or "buckling." Many people report that changes in the weather also affect the degree of pain from arthritis.

Prevention:
Exercise regularly, but don’t participate in high-impact exercises like running, which can hasten the progress of arthritis. Lose weight because even small amounts of weight loss can improve symptoms and slow progress. Appropriate diet is important. The physician may want to discuss oral supplements such as vitamins, minerals, glucosamine, and anti-inflammatories.

Treatment:
In its early stages, arthritis of the knee is treated with conservative, non-surgical measures. Lifestyle modification can often minimize aggravating the condition. Exercise helps increase flexibility and range of motion. This particularly can include swimming and cycling. Use of a cane, a brace or energy-absorbing shoes can be helpful. Applying heat or ice, liniments or elastic bandages may be appropriate. Several types of drugs can be used in treating arthritis of the knee, and the orthopedist will develop a program for the specific condition. Visco supplementation, a series of injections into the knee, can help lubricate the knee.

If the arthritis does not respond to these treatments, surgery may be needed. Arthroscopic surgery uses fiber optic technology to enable the surgeon to see inside the joint and clean it of debris or repair torn cartilage.

An osteotomy cuts the shinbone or the thighbone to improve the alignment of the knee joint. A total or partial knee arthroplasty replaces the severely damaged knee joint cartilage with metal and plastic.

Total knee replacement
Most patients who undergo total knee replacement are age 60 to 80. However, orthopedic surgeons evaluate each patient based on a patient's pain and disability. People of all ages have had successful total knee replacements. By resurfacing the knees damaged and worn surfaces, total knee replacement surgery can relieve pain, correct leg deformity and help a person be able to resume normal activities. Alternatives to traditional total knee replacement surgery that the surgeon may discuss include a unicompartmental knee replacement.