Chondral Defect Knee
What is a chondral defect or cartilage defect?
A chondral defect refers to a specific, localized area of damage to the articular cartilage that lines the ends of the bones (like a tile missing in the floor). Articular cartilage is the coating of the bones and allows for smooth motion between the ends of the bones. It is a common injury affecting 5-10% of people over age 40, but it can also affect young patients that experience traumatic injuries. Damage to knee cartilage can lead to osteoarthritis of the knee over time.
Focal chondral defects are graded by severity. Grade I is the mildest and grade IV is the most severe describing full thickness injury of the cartilage.
What causes a chondral defect?
Damage is typically caused by an acute traumatic injury such a sudden pivot or twist with a bent knee, or a fall or direct blow to the knee. When the underlying bone beneath the cartilage is also damaged it is called an osteochondral injury.
What are the symptoms?
The purpose of articular cartilage is to provide smooth movement between the bones that make up the joint. A focal injury to the cartilage can cause pain, joint stiffness, intermittent swelling, and catching or locking of the knee joint when there is a loose fragment of cartilage.
How is chondral injury diagnosed?
Dr. Jorge Chahla will review the patient’s health history and ask about the circumstances surrounding the injury, activities that cause pain, and identify the patient’s future activity goals.
The physical examination will test joint laxity, joint line pain, misalignment, and assess range of motion, stability, and gait. However, physical exam alone may not reveal the damage. X-rays will rule out arthritis, bony defects, and misalignment. Other imaging may also be ordered such as MRI. MRI is a sensitive technique to diagnose chondral injuries. However, the most reliable diagnosis is made with knee arthroscopy using a small camera inserted into the joint where the lesion can also be treated, measured, or biopsied if further treatment is needed down the line.
How is a chondral defect treated?
The choice of treatment will depend on the size of the defect, its location, and the patient’s goals. Chondral defects are difficult to treat and can sometimes require surgical repair if all conservative measures have failed.
Conservative treatment is usually recommended initially. It will include anti-inflammatory medications, icing, therapy to strengthen the muscles and improve flexibility, and activity modification. In addition, protective supplements of glucosamine and chondroitin may be recommended in specific cases. Other nonsurgical options include injections of steroids or hyaluronic acid, and weight loss. These treatments will not regenerate the cartilage, but they might help treat the symptoms.
The goal of surgery is to improve symptoms, and restore function. In the past decade, there have been significant advancements in the surgical treatment of chondral defects. Cartilage restoration is one of Dr. Chahla’s areas of expertise which is surgery aimed at restoring the articular surface in young, active patients.
- Arthroscopic Debridement is a procedure used for symptom relief. It removes cartilage fragments, smooths the edges of the defect, and decreases friction and irritation. This is usually a good first approach to cartilage injuries because most people will improve with this “minimally invasive” procedure that has almost no downtime and allows Dr. Chahla to determine the severity of the injury
- Arthroscopic microfracture is a procedure to create a controlled injury to the bone that will stimulate the bone to create a product similar to cartilage (called fibrocartilage). Fibrocartilage is not as good as articular cartilage, but can improve symptoms in certain patients. Tiny holes are made in the bone causing it to bleed sending bone marrow into the defect to grow new fibrocartilage. Microfracture can be used for patients with limited small cartilage injuries, who are active and desire to return to activity; however, its use has been declining in the last decade.
- Cartilage transplant or autologous cultured chondrocytes (cartilage cells) on a collagen membrane [MACI] can be used to treat focal cartilage defects. This is a two-stage cell-based procedure, because it requires an initial arthroscopic procedure to harvest the cells (small biopsy from your cartilage). The patient’s own cartilage cells (chondrocytes) are harvested from a non-weight bearing joint and grown (cultured) in a lab over several weeks. The lesion is also debrided to remove damaged cartilage at this initial procedure. When ready, the cultured cells are implanted into a membrane which will then cover the cartilage defect. Because the transplants are made of the patient’s own cells, there is no risk of rejection. MACI is best for younger patients that want to remain active and can commit to post-op rehabilitation. It is most commonly used for patellofemoral (knee cap) cartilage injuries.
- Autografts of cartilage and bone (osteochondral autograft) can also be used to treat these injuries. This procedure is accomplished in one stage. The cartilage graft is harvested from the patient (autologous) and implanted into the defect. Healthy cartilage is harvested from non-weight bearing portions of the joint. This procedure is best for smaller lesions.
- Allografts from a donor are designed to treat all lesion sizes (osteochondral allograft). This procedure is best for active patients with localized but large defects. These grafts are harvested from a donor and the fresh graft is implanted into the lesion. Survival rates have been reported to be excellent even at 10 years.
Dr. Jorge Chahla, MD, PhD is an orthopedic surgeon in Chicago, Illinois and specializes in the treatment of complex knee, hip, and shoulder injuries and all sports related injuries. One of his areas of expertise is joint preservation and cartilage restoration techniques. Contact Dr. Chahla to schedule a consultation for yourself or someone you love.