ACT now to be back on your feet

A SPORTS person with cartilage injury in the knee? It is highly unlikely that any treatment will be able to restore the knee to its original strength and quality especially if it is the articular cartilage that is injured. Cartilage that acts as a cushion between the two bones has little power to heal and repair itself. This inability arises, as the cartilage gets very little oxygen and nutrient supply from the blood.

Traditionally the recourse has been to either rest the knee forever or resort to more aggressive methods of repairing the cartilage. Enter the invasive methods that target only the ulcers in the cartilage. The most commonly resorted technique is to create a small fracture in the bone and allow blood to bleed in to the injured site. What follows is the sudden availability of oxygen and nutrients at the injured site and formation of a cartilage. Whether it is the stem cells from the blood or the self-healing capability of the cartilage that helps in the formation of a new cartilage is not known.

"But what is indeed known is that the cartilage that is formed is of an inferior quality. It lacks the biomechanical and visco-elastic characteristics of the original cartilage. The long-term durability of the new cartilage is thus doubtful," asserted Tan Jee Lim, consultant orthopaedic surgeon, Changi Sports Medicine Centre, Singapore. And the injured knee is forever a weak one.

Another technique known as mosaicplasty involves transplanting the cartilage from another site to the injured place. But the technique is fraught with problems. For one it is not just the cartilage alone that is transplanted. A small hole is drilled and the bone along with its cartilage is removed and transplanted to the injured site. The drilled bit is just put in place with no means of securing it. This leads to the problem of the transplanted bit moving up and down with time. Another area of concern centres on the inability of the transplanted piece to have the same curvature as the original one. Finally the integration of the transplanted cartilage with the surrounding cartilage poses problems.

The Changi Sports Medicine Centre in Singapore has now been working on a totally different technique that promises to provide better quality cartilage that lasts longer sans the problems seen in the traditional methods.

It is a two stage surgical procedure wherein a small piece of healthy cartilage weighing not more than 300mg is removed. The cartilage cells (chondrocytes) are freed from the encasing collagen network and allowed to multiply in number by providing oxygen and nutrients in a laboratory. The number of cells increases from an initial 1-3 million to 13 million.

The next stage is when another surgery follows wherein the cultured cells are put at the site of injury and immobilised after 4-6 weeks. The transplantation involves only the cells minus the collagen. With time the cells produce the collagen that scaffolds them to produce a cartilage. It may be noted that the cartilage produced only a type II hyaline cartilage.

"After transplantation, we protect the patient so that the young cells are not too stressed out. One of the measures of success is to measure the type and quantity of collagen in a transplanted area," said Dr. Lim. Rehabilitation through exercise is one of the core areas that determine the success of the procedure.

Called the articular cartilage implantation (ACT), the technique is suitable only for cartilages damaged by direct injury. "And we recommend this for the young for whom it is early for a knee replacement surgery," Dr. Lim pointed out.

This rules out osteoarthritis patients whose articular cartilage is damaged all through and not at certain points. Again patients who are overweight or have an underlying genetic problem or with maltracking of the knee (knee does not move in the proper alignment) are suitable for this procedure.

The downside to the procedure is the cost (Singapore $10,000-15,000) and the relatively longer duration for the completion of the procedure. The Centre has been doing this procedure since last year. Dr. Lim however supports the cost as it can get the patient to return to sports in just one year's time and high impact sports in about two years' time.

R. Prasad

in Chennai

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