Cartilage Repair & Cartilage Allografting
The articular cartilage covers the bony surfaces within the knee joint and is essential for optimal knee function. The articular cartilage in the knee is thicker than in most other parts of the body having to withstand significant loads during daily activities and particularly during high impact activities such as running and jumping sports.
Articular cartilage can be damaged by injury or normal wear and tear, and is often referred to as Condral Damage. Because cartilage does not heal itself well, doctors have developed surgical techniques to stimulate the growth of new cartilage. Restoring articular cartilage can relieve pain and allow better function. Most importantly, it can delay or prevent the onset of arthritis.
The symptoms of an articular cartilage injury are not as obvious as those of a meniscus tear or ligament injury. Symptoms can include:
Intermittent swelling - This is often the only symptom, with the loose cartilage fragments floating in the knee causing swelling to occur.
Pain - Pain can occur with prolonged walking or stair climbing.
Giving way - The knee may occasionally buckle or “give way” when placing weight on it.
Locking or catching - The loose, floating pieces of cartilage may block the joint as it bends, causing the knee to lock or catch.
Noise - The knee may make noise during motion, especially if the cartilage on the back of the kneecap is damaged.
An articular cartilage injury, or chondral injury, may occur as a result of a pivot or twist on a bent knee, similar to the motion that can cause a meniscus tear. Damage may also be the result of a direct blow to the knee. Chondral injuries may accompany an injury to a ligament, such as the anterior cruciate ligament. Small pieces of the articular cartilage can actually break off and float around in the knee as loose bodies, causing locking, catching, and swelling.
More often, there is no clear history of a single injury. The patient’s condition may result from a series of minor injuries that have occurred over time. Articular cartilage also wears down as we age.
Articular cartilage degeneration is often treated without surgery. Some measures the orthopaedic surgeon may recommend are:
Weight loss and changes in physical activity
Exercises to strengthen the muscles around the joint
Shock absorbent shoe inserts
Injections of hyaluronic acid to improve joint lubrication and reduce friction
Your doctor will usually prescribe medications to treat the symptoms and will monitor your progress. Although there are medicines that can treat the symptoms associated with articular cartilage damage, there are no medications that can repair or encourage new growth of cartilage.
Further treatment would require a surgical procedure. The most common surgical treatment involves smoothing the rough areas of the defect with a shaving technique. Factors that influence the choice of procedure include:
The size and location of the defect in the knee.
The age and weight of the patient.
The patient’s future goals and activity level.
The patient’s motivation and ability to participate in postoperative rehabilitation.
The patient’s limb alignment: Is the patient bow-legged or knock-kneed?
This arthroscopic technique of shaving, or debridement, has been popular for 20 years and has had very satisfactory results for over 75% of patients. It is a common treatment for patients with a cartilage defect that has not worn all the way down to the bone, especially under the kneecap. This procedure is also used in the more arthritic knee when other resurfacing techniques are not appropriate. Using special arthroscopic instruments, Dr. Carl Schillhammer smoothes the shredded or frayed articular cartilage. Ideally, this treatment will decrease friction and irritation, reducing the symptoms of swelling, noise, and pain.
The patient’s commitment level to the rehabilitation process is an important factor in determining the outcome of the treatment. Crutch use is minimal and rehabilitation is started immediately after surgery. Regular activities are often resumed within 4-6 weeks.
The healthy knee joint features articular cartilage that acts as a lubricant between the bottom of the femur (thigh bone) and the top of the tibia (shin bone). Healthy articular cartilage is smooth white tissue. This lubricating cartilage is present in all of our joints and allows the bones to glide properly with little friction.
This cartilage, however, can be damaged by a traumatic injury to the joint, or it can simply degrade over time from wear or the effects of arthritis. Unfortunately, unlike other ligaments, muscles and tendons, cartilage doesn’t repair itself well.
Consequently, physicians have developed surgical techniques to help stimulate the growth of new cartilage. The goal with restoring cartilage is to relieve pain symptoms and allow improved function of the joint. Equally important, efforts to repair this damaged cartilage can delay the onset of arthritis.
The knee is the most common joint where cartilage restoration surgery is performed, although the ankle and shoulder could also be addressed this way. Typically young adults are the best candidates for surgery intended to repair cartilage. Older patients tend to do less well with this approach.
The two common approaches to repairing cartilage is an “autograft” where cartilage is harvested from the person’s own body, and “allograft” where cartilage is sourced from a tissue bank where it was harvested from a cadaver and sterilized. The main limit with autograft is that there are great limitations to the amount of cartilage that can be harvested from within a patient’s own knee, so large areas needing repair wouldn’t be possible. Consequently, most surgeons prefer allografts as it provides the most flexibility and ease of installation.
How cartilage allograft surgery is done
During an osteochondral allograft surgery, the surgeon uses an allograft of donated human decellularized hyaline cartilage and cancellous bone.
The surgeon identifies the damaged cartilage and using surgical instruments removes the segment of cartilage along with a small piece of underlying bone. A replacement core is then size to fit into the hole. The replacement insert is then gently tapped into place until it lines up with the surrounding tissue. No other screws are needed to keep the insert in place.
After cartilage allograft surgery, patients can usually start to put weight on the joint after a month or so. Activity can be increased slowly over 6 months where the person can return to their sport or recreational activity.
In a study of 211 cartilage allograft patients, a University of California, San Diego study found an overall success rate of 84% at the follow up point of 4 years. Because an allograft involves tissue harvested from a cadaver, there is a small risk of disease transmission, such as hepatitis C or HIV.. This risk can managed by using tissue from a certified American Association of Tissue Banks. Other issues can relate to autoimmune reactions to the tissue implant.
Overall, researchers conclude that an osteochondral cartilage allograft is one of the most promising ways to provide athletes and highly active patients the ability to return to their favorite sport or recreational activity after surgery.
The other significant benefit of the allograft surgery is that it can delay the need for a knee replacement for many patients in their thirties, forties and fifties. The life of an artificial knee joint can range from 15 to 20 years, so a knee surgeon will often try to delay that implant as long as possible so the patient doesn’t outlive the lifespan of the artificilal joint, which can require a more complex knee revision surgery to remove the worn out artificial knee joint and replace it with a second joint.
We are one of the few knee specialists in the State of Montana to provide osteochondral cartilage allograft surgery. We believe that it is one of the best ways to relieve knee pain related to cartilage damage and delay the need a total knee replacement.