Articular cartilage is a complex avascular (no blood supply) tissue which consists of cells called chondrocytes suspended in a collagenous matrix. It appears as a smooth, shiny, white tissue at the ends of the bones which come in contact with each other to form a joint.
This cartilage is subjected to the normal wear and tear and may sometimes get damaged because of injury causing pain and impaired function.
Articular cartilage reduces the friction when the bones glide over each other and makes the movements smooth and enables the joint withstand weight. Alternately, it acts as a shock-absorber.
Articular cartilage injuries occur as a result of sports injury (direct blow) or progressive degeneration (wear and tear). Degeneration of the cartilage occurs as a progressive loss of structure and function of the cartilage. The process begins with softening of the cartilage which then progresses to fragmentation. As the articular cartilage lining is lost, the underlying bone has no protection against the normal wear and tear and it starts breaking down leading to osteoarthritis. The risk factors that can contribute to osteoarthritis include twisting injuries, abnormal joint structure, instability of joints and inadequate muscle strength.
The symptoms of cartilage injuries include:
Your doctor will perform a physical examination to look for altered range of motion, swelling, and alignment of the bones. As cartilage is uncalcified it does not show up in X-rays. A high quality MRI often required and arthroscopy is used as the final determination to what technique may be best used.
Initial treatment includes physical therapy, anti-inflammatory medications, and steroid injections. Surgery to restore articular cartilage may be considered for patients with large articular lesion or if conservative treatment fails. Articular cartilage repair is performed to provide relief from pain, improve range of motion, slow the progression of the damage, and delay the option of joint replacement surgery.
Indications for surgery
Surgery is usually not necessary when the cartilage defect is small and asymptomatic. Defects which are smaller than 2 cm can be treated arthroscopically and larger defects may require transplantation of cartilage from other areas of the joint. Most of the cartilage restoration procedures are done using an arthroscope.
The surgical procedures for cartilage restoration include:
Following cartilage replacement your doctor may recommend physical therapy to help restore mobility to the affected joint.
Cartilage Repair and Transplantation
Articular Cartilage is the white tissue lining the end of bones where these bones connect to form joints. Cartilage acts as cushioning material and helps in smooth gliding of bones during movement. An injury to the joint may damage this cartilage which cannot repair on its own. Cartilage can be damaged with increasing age, normal wear and tear, or trauma. Damaged cartilage cannot cushion the joints during movement and the joints may rub over each other causing severe pain and inflammation.
Cartilage restoration is a surgical procedure where orthopedic surgeons stimulate the growth of new cartilage that restores the normal function. Arthritis condition can be delayed or prevented through this procedure.
Several techniques are employed for cartilage restoration including dietary supplements, microfracture, drilling, abrasion arthroplasty, osteochondral autograft, and allograft transplantation.
Dietary supplements: Dietary supplements such as glucosamine and chondroitin are the non-surgical treatment options for cartilage restoration. Chrondroitin sulphate and glucosamine are naturally occurring substances in the body that prevent degradation of cartilage and promote formation of new cartilage. Chrondroitin sulphate and glucosamine obtained from animal sources are available as over the counter products and are recommended for cartilage restoration. Apart from these various other nutritional supplements are also recommended such as calcium with magnesium and vitamin D as a combination, S-Adenosyl-Methionine and Methylsulfonylmethane.
Microfracture: In this method numerous holes are created in the injured joint surface using a sharp tool. This procedure stimulates healing response by creating new blood supply. Blood supply results in growth of new cartilage.
Drilling: In this method a drilling instrument is used to create holes in the injured joint surface. Drilling holes creates blood supply and stimulate growth of new cartilage. Although the method is similar to microfracture, it is less precise and the heat produced during drilling may damage other tissues.
Abrasion Arthroplasty: High speed metal-like object is used to remove the damaged cartilage. This procedure is performed using an arthroscope.
Osteochondral Autograft Transplantation: Healthy cartilage tissue (graft) is taken from the bone that bears less weight and is transferred to the injured joint place. This method is used for smaller cartilage defects.
Osteochondral Allograft Transplantation: A cartilage tissue (graft) is taken from a donor and transplanted to the site of the injury. Allograft technique is recommended if larger part of cartilage is damaged.
Autologous Chondrocyte implantation: In this method a piece of healthy cartilage from other site is removed using arthroscopic technique and is cultured in laboratory. Cultured cells form a larger patch which is then implanted in the damaged part by open surgery.
Osteoarticular transfer system (OATS): Osteoarticular transfer system (OATS) is a surgical procedure to treat isolated cartilage defects which usually 10 to 20mm in size. The procedure involves transfer of cartilage plugs taken from the non-weight bearing areas of the joint and transferring into the damaged areas of the joint.
This procedure is not indicated for wide spread damage of cartilage as seen in osteoarthritis.
The procedure is usually performed using arthroscopy. During the procedure the plugs taken are usually larger and therefore only one or two plugs are needed to fill the area of cartilage damage. The area of damaged cartilage is prepared using a coring tool which makes a perfectly round hole in the bone in the area of damage. The hole is drilled to a size that fits the plug. Next the plug of normal cartilage is harvested from a non-weight bearing area of the knee, is then implanted into the hole that was created in the damaged area. The size of the plug used should be slightly larger than the hole so that it fits into the position. This procedure allows the newly implanted bone and cartilage to grow in the defected area.
Possible complications of OATS include donor site morbidity causing pain, avascular necrosis, and fracture. Other complications such as hemarthrosis, effusion and pain may also occur. Following OATS rehabilitation is recommended by use of crutches and limiting the range of motion.