Chondral Knee Injuries (Articular Cartilage Damage)
A chondral knee injury is the result of articular cartilage damage within the knee. Articular cartilage is a specific connective tissue covering joint surfaces. Viewed by the naked eye, it has a glistening, white appearance. Microscopically, it is composed of water, collagen and a wide array of matrix proteins and lipids.
Articular cartilage has no nerve supplies and therefore does not cause pain or sensitivity when one experiences a mild or early injury. It also cannot repair itself if damaged. Although symptoms of articular cartilage problems may not present themselves until later in life, they are very common.
Many factors play a role in chondral knee injuries including the patient's age when the degeneration starts, the patient's activity level and weight and the overall presence of ligament damage. Although cartilage damage may be in place for years, it sometimes takes a sudden injury to present symptoms. If no sudden injury occurs, arthritis and osteoarthritis will result after many years of wear and tear and bone-on-bone rubbing. This will cause a myriad of symptoms for the patient.
Chondral damage is graded from mild to severe, and all grades can have characteristics of osteoarthritis.
- Grade 0: normal cartilage
- Grade I: In this early stage, cartilage starts to become soft with swelling
- Grade II: This stage will present a partial-thickness defect with fibrillation (shredded appearance) or fissures on the surface that do not reach the bone or exceed 1.5 cm in diameter.
- Grade III: This stage presents an increased amount of fibrillation and fissuring to the level of subchondral bone in an area with a diameter more than 1.5 cm. Patients will often complain about noise as the knee bends and soreness or trouble standing from a squatted position.
- Grade IV: This phase will present an exposed subchondral bone—meaning, the cartilage may wear away completely. When the involved areas are large, pain usually becomes more severe, causing a limitation in activity.
The symptoms of a chondral injury resulting from articular cartilage damage will not present themselves as prominently as a torn ACL or meniscus tear. Similar to other arthritic conditions, the symptoms start mild and continue to progress as time goes on.
Symptoms with articular knee cartilage—once they do begin to appear—include:
- Intermittent swelling (often the only symptom)
- Pain associated with prolonged walking or stair climbing
- Buckling or giving way when full weight is placed on the knee
- Locking or catching
- The knee may make noise during motion
Diagnosing a chondral injury can be difficult. Many times, a swollen knee will show a normal exam. Imaging using an X-ray, MRI or via an arthroscopic examination can help determine if cartilage loss is occurring thus leaving a decrease in space between the bone surfaces.
Articular cartilage degeneration is often treated without surgery. Dr. Millett will recommend weight loss, exercises to strengthen the muscles around the joint, supplements and possibly injections of hyaluronic acid to improve joint lubrication and reduce friction. There are medications that can be prescribed to help treat symptoms associated with chondral injuries. However, since new growth of cartilage is not a possibility, medication will not cure the condition, but simply allow the patient to live pain-free or more active than before. Further treatment would require a surgical procedure.
Over the past decade, there have been big strides and exciting advancements in the surgical treatment of articular cartilage defects. The most commonly performed procedures for treating chondral defects are Shaving and Microfracture.
Shaving (or Debridement)
This arthroscopic surgery technique that uses special arthroscopic instruments to smooth 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 arthroscopic technique encourages the growth of new cartilage into the 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 to the bone).