There are three types of cartilage in the body, elastic cartilage, fibrocartilage, and hyaline cartilage. These three types of cartilage vary in composition and location. For example, elastic cartilage is more easily able to stretch and is found in the ear lobe. Fibrocartilage is tougher and is found in the intervertebral discs in the spine or the menisci ligaments in the knee. Hyaline cartilage is smooth and it is found on the ends of bones that make up joints, which is referred to as articular cartilage. Articular cartilage is only 2-4 mm thick, but it is important because it allows the joint to easily glide back and forth by reducing the friction; in fact, articular cartilage is more slippery than ice!
Articular cartilage does not have a blood supply, so the nutrients are received by diffusion, which means as the cartilage compresses, nutrients are delivered to the cartilage. Also due to lack of blood supply, if cartilage is damaged, it is slow or is completely unable to repair itself. This is a significant problem especially for those patients who suffer an ankle sprain or ankle fracture, because 50% of ankle sprains and 73% of ankle fractures have an associated cartilage injury to the talus. The talus is the bone that connects the foot to the leg bones (tibia and fibula), which makes up the ankle joint. Covering the talus is articular cartilage and when the articular cartilage and/or underlying bone are damaged, the injury is called and osteochondral defect.
Osteochondral defects can really occur at any joint, but the ankle joint is one of the most common areas for this injury to occur. These injuries most commonly are caused by trauma, such as ankle sprain or fracture or long term repetitive microtrauma.
These injuries are able to damage the cartilage as well as the underlying bone. Symptoms include:
-Joint stiffness and locking
-Clicking in the joint-maybe able to hear a click as well as feel it when moving the ankle
The diagnosis of these injuries is partially made clinically based off history of injury, location, and the symptoms. The diagnosis can be confirmed with diagnostic imagining such as x-rays and/or magnetic resonance imaging (MRI). X-rays will not show a mild injury where only the
cartilage is damaged because x-ray is unable to pick up the details of the cartilage. In this case an MRI is needed since it is able to show soft tissue, such as cartilage, as well as bone. X-rays will detect a severe injury where there is damage to the cartilage and bone or if
the damaged cartilage and underlying bone fragment has become detached. However, even if the osteochondral defect is seen on x-ray an MRI will still be ordered to better show the
extent and detail of the injury.
Unfortunately, conservative treatment is usually not effective, since as already stated, cartilage is slow growing and may not even have the capability to repair itself. However one conservative method for a mild injury would include wearing a cast to below the knee and remaining non-weightbearing for 6-8 weeks in hopes that the bone and cartilage may heal. If this fails and if the pain is affecting your life there are many surgical options to treat osteochondral lesions. The Boulder County Foot and Ankle will be able to further evaluate your injury and further discuss the most appropriate treatment for your injury.
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American Academy of Podiatric Sports Medicine