The smooth rubber like layer on the ends of bones at the joint are cartilage. They are glistening white in appearance. This highly specialized structure act as the shock absorber and provide a smooth gliding surface for movements to happen.
Unfortunately, the healing potential of this structure i.e. cartilage is poor. Any damage by injury or disease like rheumatoid and gout etc leads to permanent damage unless immediate and effective actions are taken.
Cartilage loss leads to early onset of painful movements and deformity, hallmark of osteoarthritis.
(Left): View of a normal knee joint through an arthroscope, showing smooth articular cartilage and the meniscus. (Right): Arthroscopic view of a joint surface showing a full thickness defect of articular cartilage exposing underlying bone.
As discussed earlier, no medicine or nutritional supplement can heal the injured or diseased cartilage. In diseases like rheumatoid it is important to keep the disease process under control to prevent damage to cartilage.
During injury, the partial loss of cartilage layer needs only rest or offload the joint till healing has taken place. Full thickness loss of cartilage layer requires surgical procedures.
The severity of cartilage injury is classified using the Outerbridge Classification system, a scale from 0 to 4, with 0 being normal and grade 4 being complete exposure of the bone under cartilage layer.
Most problematic cartilage lesions are at least 2 cm in diameter, but may often be as small as 1 cm in diameter or as large as 4 cm in size. These areas of cartilage loss interfere with normal joint mechanics, and result in pain and poor joint function in affected individuals. Diagnosis Patient history of injury, unusual activity, disease and physical evaluation, gives us some idea about the suspected cartilage abnormality. Advanced imaging modality like Magnetic Resonance Imaging (MRI) has increased the chances of diagnosis greatly. It also helps the surgeon in formulating a treatment plan. Accuracy rate even with MRI scan remains 85% to 90%. Hence the surgeon need to have a backup plan also.
Figure 3: MRI showing a healed osteochondral allograft
There are many ways to bell the cat. Options are based on a variety of factors, including the patient's age, patient activity level, overall condition of the joint, the size and location of the lesion, the patient’s ability to participate in rehabilitation, and whether the patient is to return to sports.
Broadly speaking there are two aspects to cartilage injury situation, one is the pain and blocking of knee movements by loose fragment of cartilage after injury. Removal of this offending piece takes care of so called 'locking episodes' and immediate problem of pain. Recommended as a short term measure for sports man needing to go back to field urgently or old patient with already arthritic patient requiring replacement surgery. They both require another surgery later on.
Second aspect is to prevent long term complication of osteoarthritis by creating conditions for biological healing of cartilage- with cartilage tissue.
The first option alleviates the patient,s immediate problem. Managed through key hole surgery, i.e. Arthroscopy. In cases where diagnosis is doubtful, a look in to the joint confirms the injury pattern and one can plan for definitive care lateron.
Here we employ cartilage healing or regeneration techniques
One of the earliest techniques to promote natural healing by stimulating local healing process. The loose fragments are taken off and small holes are made in the bone at the crater. The holes allow clots to form (in response to the injury); over time, the clots change into a cartilage tissue. This method is useful for small defects onlyhealing process has its limitations and the tissue is more of a scar tissue.
Arthroscopic view showing the articular cartilage surface following microfracture *Note the tiny holes in bone. Among elite athletes we have found that only 40% were able to return to sport after the surgery.