How is an articular cartilage injury treated?
Articular cartilage degeneration is often treated without surgery. Some measures that the physician may recommend are:
exercises to strengthen the muscles around the joint.
shock absorbent shoe inserts.
changes in physical activity.
glucosamine and chondroitin supplements (not FDA regulated).
injections of hyaluronic acid to improve joint lubrication and reduce friction.
The doctor usually prescribes medications to treat the symptoms and watches the patient's 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.
In the past 10 years, there have been many exciting advances in the surgical treatment of articular cartilage defects. The most commonly used treatment involves smoothing the rough areas of the defect with a shaving technique; however, significant research in this area of medicine has led to the development of several new ways to address this difficult problem.
Factors that influence the choice of procedure include:
the size of the defect.
the 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?
The most commonly performed procedures for treating chondral defects are Shaving and Microfracture.
Shaving or Debridement
This arthroscopic technique 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, the physician smoothes the shredded or frayed articular cartilage. Ideally, this treatment will decrease friction and irritation, reducing the symptoms of swelling, noise, and pain.
Microfracture or Abrasion
This technique encourages the growth of new cartilage into a defect. This is a well-accepted technique that is a common procedure for patients with damage through the full thickness of articular cartilage, all the way down to the bone. Using an arthroscopic procedure, the base of the damaged area is scraped to create a bleeding bed of bone. Blood is essential for healing. Small holes are then "picked" into the defect with a special instrument, allowing blood vessels and bone marrow cells to be in contact with the exposed cartilage defect. Bone marrow then fills the defect promoting the formation of a clot, which will eventually mature into firm scar cartilage. Research has shown that this tissue is a hybrid cartilage. Although this newly grown cartilage is durable and can function for many years, it may not have the same durability or strength as the original hyaline cartilage that existed before the injury.
The following procedures to repair articular cartilage defects are currently being researched and evaluated. Although these newer techniques hold some promise, their effectiveness and long-term outcomes have not been established and only a few surgeons perform them. Some of these procedures can be very costly. The patient should check with the insurance company before proceeding with any of these techniques.
Osteochondral Autograft Resurfacing
Ideally, defects of the articular cartilage in the knee would be replaced with normal hyaline cartilage. This cartilage would withstand years of use and prevent the development of arthritis. Osteochondral autograft resurfacing offers some hope in achieving this goal. The advantage of this treatment is that the patient's own cartilage is used to repair the damaged area.
This procedure involves the transfer of normal cartilage from one area of the knee to another. Cartilage plugs are taken from areas of the knee that do not bear the weight of the body during walking, and then "planted" in the damaged areas with a technique that is similar to the one used for a hair transplant.
This procedure is best for defects smaller than 15-20mm in size because there is a limit to the number of plugs that can be harvested. It is not recommended for osteoarthritis, in which the cartilage is thinning around the defect. This procedure can be done arthroscopically except when multiple plugs are required. In the case of a larger defect, a small incision may be necessary to position the plugs correctly.
Autologous Chondrocyte Implantation
This procedure is most commonly reserved for defects over 20 mm in size or when the damaged site is too large to be reliably treated with other techniques. It is only recommended if there is no cartilage wear around the defect.
This treatment involves using the patient's own cartilage cells. The patient's articular cartilage cells are arthroscopically removed from the injured knee and grown outside the body in tissue culture. After a growth period of three weeks, a second surgical procedure is performed to implant these cells into the defect. Ideally, these cells will fill the defect with a new cartilage surface over time. The implantation process requires a large incision so that the cartilage cells can be properly placed on the bone surface and begin to grow. It takes two to three years for these new cells to mature completely.
Osteochondral Allograft Resurfacing
This procedure is used if there is bone damage in combination with articular cartilage defects. It requires the transplantation of fresh cartilage and bone from a donor, soon after that person's death. One large graft is implanted into the damaged area. (The tissue banks that provide grafts carefully screen the donors for infectious diseases, including AIDS and hepatitis.) Although this procedure has been done for over 20 years, it has only recently gained popularity because fresh grafts have become more readily available.
What types of complications may occur?
None of the above procedures are perfect, but each one may be helpful for patients with painful articular cartilage defects. Although the results have not been evaluated in controlled trials, these techniques have been shown to be safe and effective with positive results in the 70-80% range. The success rate seems to be time dependent. Some patients may have relief from symptoms for a short time, but find that symptoms gradually reoccur. Long-term results are still not available for some of the procedures. Joint stiffness, infection, and continued pain may sometimes follow surgery, as can happen with any major knee operation.
The decision to choose any of these procedures should be made only after the patient and physician have carefully discussed all the options. Adequate training and experience in the use of any of these techniques is important to the success of the chosen procedure.