Different Types of Knee Injuries and Their Causes

Most often due to sports, recreational activities, work tasks or home projects, knee injuries of some sort can happen to anyone. Knee injuries can be a result of anything from basic wear-and-tear or overuse injuries to specific, acute injuries.

Knee Anatomy

The knee is made up of four primary anatomical elements: the bones, cartilage, ligaments and tendons.

• Bones: Three bones combine to form the knee joint: The thigh bone (femur), the shinbone (tibia) and the kneecap (patella).
• Cartilage: There are multiple areas of cartilage, a slippery substance that helps facilitate movement, in the knee. The articular cartilage covers the ends of the femur and tibia, along with the back of the patella. It helps the knee bones glide smoothly as you bend or straighten your leg. The meniscus, on the other hand, describes two wedge-shaped pieces of cartilage between the femur and tibia. This cartilage is tougher and more rubbery than the articular cartilage, and helps cushion and stabilize the joint like a shock absorber. Torn cartilage in the knee is generally a torn meniscus.
• Ligaments: Ligaments connect bones to other bones. Two collateral ligaments (medial on the inside, lateral on the outside) are found on the sides of the knee, while another two cruciate ligaments (anterior in the front, posterior in the back, crossing to form an X) are found inside the knee joint itself. Cruciate ligaments handle the back-and-forth motion of the knee.
• Tendons: These connect muscles to bones. The quadriceps tendon connects the front thigh muscles to the patella, while the patellar tendon connects the shinbone to the patella.

Acute Injuries

Acute injuries, or sudden injuries, are the most common cause of knee problems. They can be caused by a blow to the knee or from twisting, bending or falling on the knee. Symptoms can range from pain and bruising to numbness, weakness, tingling and other symptoms. These injuries include:

• Strains, sprains or other ligament and tendon injuries
• Meniscus tear
• Ligament tears, such as to the ACL (anterior cruciate ligament) or MCL (medial collateral ligament—the most commonly injured ligament)
• Breaks (or fractures) of the kneecap, lower femur or upper tibia or fibula. Generally caused by an unusual force such as falling, twisting, bending or direct contact
• Dislocated kneecap: Most common in 13-to-18-year-old girls
• Loose bodies: Pieces of bone or tissue from a fracture or dislocation that get caught in the joint and disrupt movement
• Dislocated knee joint: A rare injury that needs a large amount of force to take place. It’s very serious and demands immediate medical attention, however.

Overuse Injuries

Overuse injuries develop after repeated activities or pressure on the knee. Activities like stair climbing, riding a bike, jogging or jumping can stress the joints and lead to these injuries, which include:

• Bursitis: Inflammation of small sacs of fluid that lubricate the knee
• Tendinitis or tendinosis: Inflammation of the tendons or small tears in the tendons, respectively
• Plica syndrome: Thickening or folding of the knee ligaments
• Patellofemoral pain syndrome: Pain felt in the front of the knee after overuse, injury, excess weight or issues in the kneecap
• Iliotibial band syndrome: Irritation and inflammation of the iliotibial band, a fibrous tissue that runs down the outer part of the thigh

 

Dr. Carlson tends to be conservative with surgical treatment, and much of his training is in minimally-invasive procedures, such as arthroscopy. He believes everyone deserves a trial of a more conservative treatment before moving to more invasive treatments such as surgery. Dr. Carlson tries to spend time with patients to better understand their goals and work together to come up with a treatment plan based on those goals and their distinct medical history.

 

Knee Conditions

In some cases, knee problems can occur without being related to an injury or specific overuse. These are often due to specific knee conditions:

• Osteoarthritis: A degenerative joint disease that often develops after a previous injury. Other types of arthritis can also cause knee issues.
• Osgood-Schlatter disease: Causes pain, swelling and tenderness at the front of the knee under the kneecap, and is common in boys aged 11 to 15.
• Popliteal cyst: Also called a Baker’s cyst, this leads to swelling in the back of the knee.
• Infections: In the skin (cellulitis), joint (infectious arthritis), bone (osteomyelitis) or bursa (septic bursitis), these can lead to pain and issues with knee movement.
• Outside issues: Issues elsewhere in the body like pinched nerves or issues in the hip can lead to knee pain.
• Osteochondritis dissecans: A cause of pain and decreased movement after bone or cartilage (or both) inside the knee joint loses blood supply and dies.

 

Treatment methods range from basic first aid and rest to therapy, medicine and surgery in some cases. This will depend on several factors, including the severity of your injury, location, your health and other factors. If you have a knee issue, your doctor will recommend a course of treatment.

Sources:

“Knee Problems and Injuries – Topic Overview.” WebMD. http://www.webmd.com/pain-management/knee-pain/knee-problems-and-injuries-topic-overview#1

“Common Knee Injuries.” American Academy of Orthopaedic Surgeons.” http://orthoinfo.aaos.org/topic.cfm?topic=a00325