You’re watching your daughter play in the high school championship soccer game. She runs down the field, plants her foot, and cuts sharply to her left. Suddenly, she grabs her knee. After the game, her knee is swollen and stiff, and she tells you it’s really sore.

When these symptoms don’t go away after a few days, you set up a doctor’s appointment. After doing a physical examination and running some diagnostic tests, the orthopaedist tells you that your daughter has suffered an injury to the articular cartilage, a type of connective tissue that covers the ends of the bone in joints like your knee and elbow.

Articular cartilage injuries are a common joint injury, especially among those who are physically active. This type of injury most frequently occurs in the knee, but it may also involve the hip, elbow, shoulder, and ankle. While articular cartilage injuries can be painful and may make it difficult to go about your daily activities, there are several treatments available to both relieve bothersome symptoms and repair and restore damaged articular cartilage.

“The treatment of cartilage injuries remains one of the most difficult challenges in medicine. Articular cartilage injuries are difficult to treat successfully and require technical expertise,” says Christina Allen, MD, chief of Yale Medicine Orthopaedics & Rehabilitation Sports Medicine and head team physician for Yale Athletics.  

To understand articular cartilage, it’s best to start with the basics. Cartilage is a tough but flexible tissue that helps keep joints in good working order.

A joint is the area where the ends of two or more bones join one another. For instance, the knee is the joint where the shinbone (tibia), thighbone (femur), and kneecap (patella) all come together.

The most common type of joint is known as a synovial joint, which allows for a lot of movement. Synovial joints include the knee, elbow, hip, ankle, and wrist. The bones that meet at synovial joints are covered with a thin layer of cartilage known as articular cartilage. (Articular simply means “having to do with joints.”)

Articular cartilage forms a smooth, durable covering (almost the consistency of linoleum) at the end of each bone in the joint. Fluid from within the synovial joints lubricates this cartilage, allowing the opposing bones to slide over one another—for instance when the knee or elbow bends—smoothly and with little friction.

Articular cartilage is one of two types of cartilage found in the joints. The other is known as meniscus cartilage, which can also be found in the knees and which acts to distribute load between the articular cartilage surfaces.

While articular cartilage is strong, as well as capable of bearing heavy loads and withstanding decades of use, it can become damaged by injury or overuse.

Articular cartilage injuries can result from a number of causes, including:

• Forceful impacts to the joint as a result of sports injuries or a fall
• Repetitive smaller impacts to the joint
• Twisting the joint while it bears weight, for instance twisting the knee while the foot is planted
• Progressive wear and tear, usually over several decades of use
• Poor alignment of joints due to a congenital (meaning “at-birth”) abnormality or previous injury

Articular cartilage injuries most frequently occur in the knee, but they may also involve the hip, ankle, shoulder, and ankle.

In many cases, the damage is limited to the thin layer of articular cartilage at the end of a bone, which is referred to as a chondral injury or chondral defect. (Chondral simply means “relating to cartilage.”) Chondral injuries typically don’t heal well on their own, in part, because articular cartilage does not have a blood supply, which promotes healing.

Articular injuries can cause a number of symptoms, including:

• Pain and/or swelling in the joint
• A “catching” feeling when bending or moving the joint
• A crackling, grating, or popping sound and sensation that occurs when bending or moving the joint
• Joint locking (an inability to fully extend or bend the joint)
• Feeling that the joint may give way or is unstable
• Stiffness
• Reduced range of motion

Some articular injuries do not cause any symptoms.

Diagnosing cartilage injuries and damage usually entails obtaining a medical history, performing a physical exam, and ordering one or more diagnostic tests.

The doctor will start by asking about pain and other symptoms in and around the affected joint. He or she may also ask about previous surgeries, whether any specific injury precipitated the symptoms, and the types of physical activities typically performed.  

During the physical exam, the doctor will observe how the joint moves. He or she may bend and rotate the joint to evaluate pain, swelling, range of motion and ligament stability. He or she may also ask the patient to move in certain ways; for instance, if the knee is injured, the patient may be asked to perform a squat, walk, or “duck walk.”

Imaging studies, including a weight-bearing X-ray and/or a magnetic resonance imaging (MRI) study, may also be needed. These tests allow a doctor to detect and determine the severity of any damage to the articular cartilage, underlying bone, and surrounding tissues and ligaments. In patients with arthritis, in which cartilage loss is extensive, weight-bearing X-rays will show the bones touching one another.

Sometimes, a procedure called arthroscopy is done to help diagnose articular cartilage injury or damage. Arthroscopy is a minimally invasive surgical procedure in which a surgeon makes a one or two small incisions on the skin around the affected joint, then inserts an arthroscope—a thin, pencil-sized tube equipped with a camera—and surgical tools into the joint. The camera transmits a video of the inside of the joint to a monitor, which allows the surgeon to see the structures and tissues of the joint. 

The outlook is good for patients with these injuries, although not everyone will be able to resume all activities. Pain and discomfort can be relieved with both nonsurgical and surgical treatments. When the articular cartilage is damaged, surgical procedures can effectively repair and restore the tissue. In general, healthy individuals younger than 40 with minor articular cartilage injuries have the best outcomes and often successfully return to pre-injury activities. But not every patient is a suitable candidate for cartilage restoration or repair. These procedures are ideal for active people under age 50.

If left untreated, articular cartilage injuries can lead to the development of osteoarthritis, a condition in which the articular cartilage wears away, exposing the underlying bone. Joint replacement surgery may be required to treat osteoarthritis.

“Our experienced providers will assess your condition and help you make an informed decision,” says Dr. Allen. “Our Sports Medicine surgeons are fellowship-trained and have expertise in meniscus transplant, osteochondral autograft and allograft procedures, and 2^nd and 3^rd generation cartilage restoration procedures.”