Articular Cartilage Injury

If you have previously suffered a traumatic knee injury such as an ACL tear, you are especially at risk for an articular cartilage defect.

Articular cartilage is the dense, fibrous cartilage cap that covers the ends of bones within the joint. In the knee, articular cartilage covers the lower end of the femur (thigh bone), the upper end of the tibia (shin bone), and the undersurface of the patella (knee cap). The articular cartilage is normally a dense, smooth, white structure that provides a very smooth, pain-free gliding surface for knee motion. An articular cartilage injury or Chondral Defect is a problem with this tissue.

Causes
Injury to the articular cartilage may be the result of a chronic wear and tear process, or may be caused by a traumatic knee injury such as an ACL tear.

Symptoms
Patients with articular cartilage injury will often complain of knee pain, especially with activity, swelling and stiffness. Other symptoms may also include the knee catching, giving way or locking.

Diagnosis
Your doctor can detect an articular cartilage injury by examining the knee and by learning more about the history of the injury or the onset of symptoms. X-rays can indirectly show evidence of injury to the articular cartilage. A magnetic resonance imaging (MRI) examination may be used to obtain more detail regarding the condition of the articular cartilage, as well as other knee structures.

Treatment
Initial treatment of an acute articular cartilage injury consists of rest, ice, elevation, anti-inflammatory medications, protected weight bearing and range of motion exercises.

• Rest . All activities that require active use of the knee should be restricted. Talk with your doctor about a plan for gradually returning to full activity.
• Ice . Ice packs may be used for about 20 minutes at a time, each hour to help alleviate pain and decrease swelling.
• Bandage/Compression Wraps . Your doctor may recommend that you use a soft elastic wrap or bandage at the knee to help reduce swelling.
• Elevation . Elevating the knee should help ease pain and swelling. Ideally, the foot should be elevated higher than the knee, and the knee should be elevated higher than the hip.
• Medication . Your doctor may prescribe an anti-inflammatory medication.
• Crutches . Your doctor may advise you to use crutches to take pressure off the knee, reduce pain and increase mobility. You should be protected with crutches if weight bearing is painful or if you are limping.
• Physical Therapy . Your doctor or physical therapist may recommend a range of motion and muscle stretching and strengthening program for your knee.

For chronic articular cartilage injury, the nonoperative treatment program typically emphasizes therapy, activity modification, bracing and energy-absorbing orthotics. Your doctor may recommend using a needle to drain fluid from the knee if the knee is swollen. Injections of cortisone and lubricating fluid may also be recommended.

Surgery may be recommended for an articular cartilage injury caused by trauma, or for a chronic wear and tear cartilage injury that does not respond to the above outlined treatment program. During the surgery, your doctor will typically make several small incisions in the knee just large enough to allow pencil-sized instruments to be introduced into the knee. Your doctor will use an instrument called an arthroscope, which is a thin tube with a tiny camera, that allows the inside structures of the knee to be seen on a television monitor, to view the inside of the knee joint. Other small arthroscopic tools will be used to perform the actual work in the knee.

The surgery may be a relatively simple arthroscopic debridement (clean out) procedure to remove fragments of torn or rough articular cartilage. If the injury to the articular cartilage is of full thickness, with a cartilage cap that is absent and an exposed bone, your doctor may recommend performing a cartilage regenerating procedure to try to recover the end of the exposed bone with a cartilage cap. There are several different techniques used by orthopaedic surgeons to regenerate articular cartilage. One of the most popular is microfracture, during which your doctor will make a series of small holes through the area of exposed bone down into the underlying bone marrow. This will release marrow tissue into the area of the articular cartilage defect and promote healing with a new cartilage cap.

Recovery Outlook
The length of recovery required will vary, depending on the severity of the articular cartilage defect. In many cases of minor wear and tear articular cartilage injury, you may respond fairly quickly to the above outlined nonoperative treatment program. After a minor arthroscopic procedure, such as an arthroscopic debridement, recovery may be fairly rapid with good recovery by 6-12 weeks after the procedure. With more advanced techniques for regenerating articular cartilage, such as the microfracture technique, recovery will be more prolonged. The initial recovery may include an extended period of touch down or non-weight bearing with crutches, as well as the use of a continuous passive motion (CPM) machine. Full recovery from a microfracture technique typically takes at least 6-12 months.