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As the biggest hinge joint in the body, your knees are designed for a lot of use. But eventually, sports, injuries, age-related changes, and just plain wear-and-tear all take their toll.

Knee pain is an exceedingly common problem among both men and women, especially those who are physically active. Most pain occurs when the slick cartilage that lines the joint surfaces begins to break down and wear away or is lost through an injury. Friction inside the joint increases, leading to pain, inflammation and loss of mobility. Until recently, joint injections, oral painkillers and physical therapy were the primary approaches to relieving symptoms. Still, those approaches can’t repair cartilage, and over time, the damage – and the symptoms – tend to become much worse.

Recently, though, medical researchers have begun looking at ways to repair and restore damaged cartilage with healthy cartilage grown from a patient’s own cells. One of the most promising techniques is matrix-induced autologous chondrocyte implantation, or MACI.

How does MACI work?

MACI takes a small sample of your own cartilage and uses that sample to grow new, healthy cartilage that can be used to cover full-thickness cartilage defects in your knee. Implanted in patients with symptoms like knee pain, swelling, stiffness and “catching” sensations, MACI has been shown to be very effective in relieving pain and restoring joint function, helping you get back to the activities you enjoy while improving your overall quality of life.

How is the MACI procedure performed?

MACI is performed in two “stages.” First, a sample of your healthy knee cartilage will be removed with a short arthroscopic procedure. The cartilage will be harvested from a portion of the joint that’s not directly involved in weight-bearing activities. Then, the cartilage cells will be grown in a lab setting on a sterile membrane (or matrix) for several weeks, creating a full-thickness cartilage “patch” for your knee joint.

During the second part of the MACI procedure, the matrix will be shaped to fit the cartilage defect in your knee, then it will be implanted – cell-side down – in the joint over the damaged area. This procedure (called an arthrotomy) uses a larger incision to expose more of the joint so it’s easier to place the matrix and secure it over the damaged area.

After your MACI procedure, you’ll be provided with a recovery protocol to follow to help protect the cartilage matrix and allow it time to fuse with the surrounding tissue in your knee. Your recovery and rehabilitation plan will be developed just for you, based on the size and area of the repair, your lifestyle and activities, and other factors.

After MACI, you’ll have restrictions on how much you can lift and weight-bearing in the joint will be restricted for up to two months as well. You’ll also need to wear a knee brace to support the joint while the cartilage fuses with the underlying bone tissue. Physical therapy will play a major role in your recovery, and you’ll work closely with your therapist to gradually build strength and flexibility in the joint as you return to your normal level of activity. Most people are able to return to work at about two to four weeks after their MACI procedure. You won’t be able to participate in high-impact sports for about six months in most cases, but some physical activities like cycling usually may begin much sooner during your recovery.

Is MACI right for you?

MACI is emerging as an effective treatment for cartilage repair, especially for people under 50 years of age. To find out if it’s a good choice for you, call OrthoIllinois at 815-398-9491 and schedule a consultation and evaluation with Dr. Geoffrey Van Thiel, a board-certified orthopedic surgeon with significant experience in MACI and other joint repair surgeries. You can get additional information at

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