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300 Longwood Avenue
Boston, MA 02115
(617) 355-6000
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My Child Has:
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Articular Cartilage Injury
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Articular cartilage is a complex, living tissue that lines the bony surface of joints. It provides a low friction surface, enabling the joint to withstand weight bearing movements, both for daily activites as well as athletic endeavors, including walking, stair climbing, and work-related activities. In other words, articular cartilage is a very thin shock absorber. It is organized into five distinct layers, with each layer having structural and biochemical differences.
Three different types of cartilage are found in the body:
- Articular or hyaline cartilage -- covers joint surfaces
- Fibrocartilage -- such as in the knee meniscus and vertebral disk
- Elastic cartilage -- such as the outer ear
These different cartilages are distinguished by their structure, elasticity, and strength. In some joints, such as the knee, both articular cartilage and fibrocartilage are found functioning side-by-side, as distinctly different structures with different functions.
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Articular cartilage injuries can occur as a result of either traumatic mechanical destruction or progressive mechanical degeneration (wear and tear).
Mechanical destruction
With mechanical destruction, a direct blow or other trauma can injure the articular cartilage. Because articular cartilage has no direct blood supply, it has little or no capacity to repair itself from mechanical destruction. However, depending on the extent of the damage and location of the injury, it is sometimes possible for the articular cartilage cells to heal. If the injury penetrates the bone beneath the cartilage, the underlying bone provides some blood to the area, improving the rate of healing.
Occasionally, an articular cartilage fragment completely breaks loose from the underlying bone. This chip, called a loose body, may float in the joint interfering with normal joint motion.
Mechanical degeneration
Mechanical degeneration (wear and tear) of articular cartilage occurs with the progressive loss of the normal cartilage structure and function. This initial loss begins with cartilage softening then processes to fragmentation. As the loss of the articular cartilage lining continues, the underlying bone has no protection from the normal wear and tear of daily living and begins to breakdown, leading to osteoarthritis.
Also known as degenerative joint disease, osteoarthritis is characterized by three processes:
- a progressive loss of cartilage
- the body's attempted to repair the cartilage
- the destruction of the bone underneath the articular cartilage
The cause of osteoarthritis is poorly understood, but lifelong moderate use of normal joints does not increase the risk. Factors such as high impact twisting injuries, abnormal joint anatomy, joint instability, inadequate muscle strength or endurance, and medical or genetic factors can contribute to osteoarthritis.
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In many cases, a patient will experience knee swelling and vague pain. At this point continued activity may not be possible. If a loose body is present, words such as "locking" or "catching" might be used to describe the problem. With mechanical degeneration (wear and tear), the patient often experiences stiffness, decreased range of motion, joint pain, and/or swelling.
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The physician examines the knee, looking for decreased range of motion, pain along the joint line, swelling, fluid on the knee, abnormal ailment of the bones making-up the joint, and ligament or meniscal injury. Injuries to the articular cartilage are difficult to diagnose, and evaluation with MRI (magnetic resonance imaging) or arthroscopy may be necessary.
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When a joint is injured, the body releases enzymes that may further breakdown the already damaged articular cartilage. Injuries to the cartilage that do not extend to the bone generally do not heal on their own. Injuries that penetrate to the bone may heal, but the type of cartilage that is laid down is structurally unorganized and does not function as well as the original articular cartilage.
Defects smaller than two centimeters have the best prognosis and treatment options. Those options include arthroscopic surgery, which can remove damaged cartilage and increase blood flow from the underlying bone (e.g. drilling, pick procedure.) For larger defects, it may be necessary to transplant cartilage from other areas of the knee (joint).
For patients with osteoarthritis, non-surgical treatment consists of:
- physical therapy
- lifestyle modification (e.g. reducing activity)
- bracing
- supportive devices
- oral and injection drugs (i.e. non-steroidal anti-inflammatory drugs, cartilage protective drugs)
- medical management
Surgical options often only provide short-term relief, and depend on the severity of the osteoarthritis:
- Tibial or femoral osteotomics (cutting the bone to rebalance joint wear) may reduce symptoms, help to maintain an active lifestyle, and delay the need for total joint replacement.
- Total joint replacement can provide relief for the symptom of advanced ssteoarthritis, but generally requires changes in a patient's lifestyle and/or activity level.
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The information on this website should not be taken as medical advice,
which can only be given to you by your personal health care professional. |
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Copyright © Children's Hospital Boston. All rights reserved. |
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