Articular cartilage — the soft white cartilage that covers the ends of the bones and helps joints to move smoothly — is vital to the structure and function of knee joints. It also helps to absorb the forces throughout the knee. Once damaged, cartilage is unable to repair itself and the joint cartilage gradually wears away.
Left untreated, this condition can develop into osteoarthritis (OA), which is not only painful, but can complicate the treatment of other medical conditions — particularly diabetes and heart disease — as it hinders physical activity, which is an important aspect of managing these conditions.
While some conditions of articular cartilage can be treated non-operatively, surgical repair techniques are often used to help ensure patients reap the best possible outcome in the long run. To better understand, let’s take a closer look at the disease process of OA.
What is OA?
OA is a complex disorder of joints. It’s characterized by structural deterioration of the cartilage, bone surrounding the joint, synovial (lubricating) lining, and neighboring structures and results in joint pain and loss of function. Knee OA is the most common form of arthritis.
OA affects more than 27 million Americans — more than 9 percent of the population, including 50 percent of adults age 65 and older and 67 percent of obese adults.
What causes OA?
There are many causes of OA, including aging, obesity, genetic predisposition, healthy cartilage cells deteriorating, and trauma. Recent studies show that elite athletes, especially those who have had cartilage and/or meniscal injuries at some point in their careers, are at a five-to-2 times greater risk of OA than the average Joe.
In the early stages of OA, the cartilage matrix begins to break down. At the end stage it is characterized by loss of the joint surface, thickening of the cartilage under the bone and formation of large bony growth or protrusion.
The good news: cartilage can be repaired, often through less-invasive arthroscopic procedures. Arthroscopic procedures are done with a small scope inserted through a tiny incision rather than a full large incision.
Surgical treatment options
Marrow stimulation. This technique involves the arthroscopically removing the calcified cartilage layer from the bone and then creating several small holes in the plate. These holes allow the marrow contents to enter the joint, adhere to the exposed bone, and eventually help repair tissue. This technique is generally reserved for smaller well-contained cartilage lesions. Newer techniques involve the augmentation of repair tissue using growth factors and protein to induce cartilage repair and a more hyaline-like (transparent and filled with collagen) tissue.
Osteochondral (bone and cartilage) grafting. The most widely used technique is an autograft (tissue taken from the individual’s own body) transplantation. This technique is generally reserved for midsized lesions. Larger lesions can be treated with allograft (tissue taken from a cadaver) transplantation. This technique allows for grafting of cartilage lesions of unlimited size and potentially at multiple sites.
Cell-based repair. Autologous cell implantation is a two-stage procedure in which a biopsy specimen of the joint cartilage is taken, cultured and ultimately re-implanted during a second procedure under a patch sutured around the cartilage defect.
Fragmented cartilage implantation. Fragmented cartilage implantation involves the selective growth of cartilage cells with favorable characteristics. It involves arthroscopically harvesting healthy cartilage from a relatively non weight-bearing segment of the joint, dividing the cartilage, and then re-implanting into the defect. This technique eliminates the need for a biopsy and a second operation.
It’s important to understand that all cartilage lesions are not symptomatic and likewise all symptoms don’t necessarily some from cartilage lesions. If you are experiencing knee pain, it’s best to be evaluated by an expert to help set up a personalized treatment plan designed specifically for you.