Knee Injuries: Common Knee Problems

Knee Injuries: Common Knee Problems

Your knee is made up of many important structures, any of which can be injured. The most common knee injuries include fractures around the knee, dislocation, and sprains and tears of soft tissues, like ligaments. In many cases, injuries involve more than one structure in the knee.

The Knee

The knee joint is composed of three bones: the femur, the tibia and the patella. The proximal tibia-fibula joint is included in the knee, but is rarely injured. Articular cartilage covers the joint surface and provides a smooth lubricated gliding surface for knee motion. The shapes of the bony articulation provide very little inherent stability. Proper function depends upon intact ligaments. This includes the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medical collateral ligament (MCL), and the lateral collateral ligament (LCL). While the ACL functions as the main stabilizer to anterior knee translation, the PCL functions as the main stabilizer to posterior translation. The collateral ligaments are the main stabilizers to side to side stress. The medial and lateral menisci are located within the joint between the femur and tibia. At times they have been referred to as the "cartilage" in the knee joint, but it is important to differentiate these structures from articular cartilage which covers the ends of the bones within the joint. The menisci function as "shock absorbers" within the knee joint and also influence knee stability.

The front of the knee is protected by the patella or kneecap, which is attached to the quadriceps muscle by the quadriceps tendon and to the tibia by the patellar tendon. While the quadriceps muscle controls knee extension, knee flexion is controlled by the hamstring muscles.

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Most common knee problems in man and women

Patella Tendinitis and Quadriceps Tendinitis

Patella tendinitis is a common injury following overuse or repetitive trauma to the extensor mechanism, such as basketball or volleyball. Patients usually present with pain in the front of their knee over the patella tendon associated with limited flexion and swelling. Treatment is directed towards a period of rest to allow the symptoms to subside followed by activity modification that limits high impact sports. Stretching and strengthening exercises are initiated once the pain subsides. Ice and short courses of NSAID's are helpful adjuncts.

In a similar fashion, the quadriceps tendon may become sore and irritated. This is usually manifested with tenderness in the soft tissue just above the patella. Treatment is similar to patellar tendinitis as discussed above.


The most common bone broken around the knee is the patella. The ends of the femur and tibia where they meet to form the knee joint can also be fractured. Many fractures around the knee are caused by high energy trauma, such as falls from significant heights and motor vehicle collisions.


A dislocation occurs when the bones of the knee are out of place, either completely or partially. For example, the femur and tibia can be forced out of alignment, and the patella can also slip out of place. Dislocations can be caused by an abnormality in the structure of a person's knee. In people who have normal knee structure, dislocations are most often caused by high energy trauma, such as falls, motor vehicle crashes, and sports-related contact.


Bursae are synovial lined cavities that overly a bony prominence around the knee. Repetitive trauma from overuse or, more commonly, chronic irritation results in local inflammation and fluid collection within the bursa. The prepatellar bursa is the most commonly affected and when inflamed is called "housemaid's knee." The bursa overlying the attachment of the medial hamstrings or pes anserinus tendons on the tibia can also become inflamed. This is usually termed a pes bursitis and is usually caused by a repetitive activity such as running. Treatment is directed at stopping the irritating activity. Ice and a short course of NSAID's are useful. A compressive wrap is sometimes helpful. Aspiration is sometimes required for extreme cases.

Patellofemoral Pain and Chondromalacia Patella

Pain in the front of the knee is a common complaint and can be the result of numerous maladies. Sources of pain include patella malalignment, chondromalacia, osteoarthritis, osteochondral fractures, synovial plica, bursitis, tendinitis, and patella instability. An understanding of knee anatomy, as it relates to the mechanism of injury, is important in establishing a diagnosis. Your physician may need to perform ancillary tests in order to finalize a diagnosis. While the initial treatment is usually nonoperative, it is sometimes necessary to perform surgery to solve the problem.

Malalignment, along with acute or repetitive trauma, can lead to degenerative changes on the surface of the patella or femoral groove. Softening and erosive changes are referred to as chondromalacia. Initial treatment includes activity modification, ice and NSAID's. As the pain subsides, an exercise program is begun that usually focuses on stretching and strengthening. For those patients with recalcitrant cases, their physician may need to modify their treatment plan and consider surgical intervention.

Anterior Cruciate Ligament (ACL) Injuries

The anterior cruciate ligament is often injured during sports activities. Athletes who participate in high demand sports like soccer, football, and basketball are more likely to injure their anterior cruciate ligaments. Changing direction rapidly or landing from a jump incorrectly can tear the ACL. About half of all injuries to the anterior cruciate ligament occur along with damage to other structures in the knee, such as articular cartilage, meniscus, or other ligaments.

Posterior Cruciate Ligament Injuries

The posterior cruciate ligament is often injured from a blow to the front of the knee while the knee is bent. This often occurs in motor vehicle crashes and sports-related contact. Posterior cruciate ligament tears tend to be partial tears with the potential to heal on their own.

Collateral Ligament Injuries

Injuries to the collateral ligaments are usually caused by a force that pushes the knee sideways. These are often contact injuries. Injuries to the MCL are usually caused by a direct blow to the outside of the knee, and are often sports-related. Blows to the inside of the knee that push the knee outwards may injure the lateral collateral ligament. Lateral collateral ligament tears occur less frequently than other knee injuries.

Meniscal Tears

Meniscal tears usually result from a twisting injury. Because the medial meniscus is less mobile than the lateral meniscus, it has a greater chance of being entrapped between the femur and tibia in the knee joint. Beyond the physical exam and x-rays, MRI has been useful in confirming the diagnosis. While some meniscal tears may heal with rest and activity modification, failure to respond to nonoperative treatment or repetitive episodes of catching or locking suggest that a surgical arthroscopy should be considered. Depending on the pattern and extent of the tear, the arthroscopy may involve either a partial menisectomy or meniscal repair. Following arthroscopy, an exercise program facilitates restoration of motion and strength.

Tendon Tears

The quadriceps and patellar tendons can be stretched and torn. Although anyone can injure these tendons, tears are more common among middle-aged people who play running or jumping sports. Falls, direct force to the front of the knee, and landing awkwardly from a jump are common causes of knee tendon injuries.