Alternate Knee Cartilage Restoration Procedures

The knee is a complex joint where three major bones come together. These are the shin bone (tibia), the thigh bone (femur), and the kneecap (patella). Connecting the knee bones are ligaments and cartilage, which also add some protection.

The knee has two types of cartilage (the strong, rubbery, and key connective tissue). The meniscus acts as a cushion between the bones, and articular cartilage covers the ends of the bones for smooth movement.

Articular cartilage can weaken and wear out with time from chronic or repetitive actions like exercise, sports, or physical work. Acute traumatic events such as a fall can cause immediate and severe cartilage damage. Symptoms of knee injuries include pain, swelling, clicking, and locking.

Cartilage does not repair itself or heal on its own unlike other tissues. Cartilage injuries usually persist for a long time (chronic) and get worse as time goes on. Surgery has traditionally been the next step if conservative treatments have not worked to relieve pain. Most procedures to repair articular cartilage are done arthroscopically.

Promising new knee therapies and minimally-invasive procedures are the exciting future of joint therapy and can sometimes replace knee replacement surgery for certain patients. Here are the procedures currently being used by Dr. Howard:

  • MACI (Matrix Associated Chondrocyte Implantation)
  • Mosaicplasty
  • OATS – Osteochondral Autograft Transfer System
  • Allograft Cartilage Transplant
  • Microfracture

MACI (Matrix Associated Chondrocyte Implantation)

MACI (autologous cultured chondrocytes on porcine collagen membrane) is made from your own (autologous) cells grown in a laboratory. These new cells are then placed on a film implanted into the area where the damaged cartilage was removed, and the film is absorbed back into the body. The cells continue to grow and solidify, filling the cartilage void. This leaves a new cartilage surface, restoring function and alleviating pain.

MACI creates functional repair tissue that allows patients to resume an active lifestyle. It alleviates symptoms and restores joint function as early as six months after the procedure. In clinical trials, MACI patients had reduced pain and improved function compared to microfracture. Those same MACI patients reported a greater ability to perform recreational and sports activities, improved overall knee function, and higher quality of life scores.


Young active adults (less than 45 years of age) with small cartilage defects (less than 2 cm) in their knee due to stress, trauma, or degenerative disease are candidates for this procedure, which involves transplantation of healthy cartilage or bone. Osteochondral tissue (cartilage with bone) is harvested from a non-weight-bearing part of the knee and transplanted to the damaged area. If the cartilage defect is too large to be safely supplied by the patient, an allograft (sterilized cadaver cartilage) may be used instead.


Like Mosaicplasty, Osteochondral Autograft Transfer (OATS) harvests bone and intact articular cartilage from a less weight-bearing part of the knee to fill the defect in the weight-bearing part. Over time, the cartilage grows into the edges of the cut area. It is often done when a person has anterior cruciate ligament tears (ACL). It can be performed arthroscopically, and repairs to the ligament and repairs to the cartilage can both be done at the same time.


Similar to Mosaicplasty and OATS (osteochondral autograft transfer system), the replacement cartilage and bone are taken for a deceased donor to replace the damaged cartilage.


Performed arthroscopically, microfracture is a procedure where small perforations are made in the knee bone, causing the bone to bleed. This blood contains bone marrow cells that stimulate cartilage growth which helps protects the injured joint. 75 to 80% of patients experience significant pain relief and improvement in the ability to perform daily activities and participate in sports. Microfracture is used more often for younger patients, who grow tissue more quickly and need an alternative to multiple knee replacements over their lifetime.

Dr. Howard also performs many other surgical knee procedures, including Patellar Realignment and High Tibial Osteotomy.


Patellofemoral realignment is used to treat symptomatic patellofemoral instability. When the kneecap (patella) moves partially or completely out of the groove at the bottom of the thigh bone (trochlear groove), patellofemoral instability occurs. This causes abnormal tracking and malalignment that can damage the muscles and ligaments that hold the knee in place. Patellofemoral realignment surgery realigns the kneecap in the groove and returns the patella to a normal tracking path.


A high tibial osteotomy realigns the knee joint through surgery. This surgery preserves damaged joint tissue and can delay or prevent the need for a partial or total knee replacement for some patients who have knee arthritis. Patients with degenerative arthritis (osteoarthritis) of the knee sometimes experience successive wearing on the menisci and articular cartilage. This limits the knee’s ability to glide smoothly with popping, catching, locking, clicking, and pain. When the knee is malaligned, the unbalanced forces cause excessive pressure on either the knee’s inner (medial) or outer (lateral) part. Malalignment and degenerative arthritis and can cause the knee’s protective tissues to wear on one side more than the other. Unless the joint damage is beyond repair, a high tibial osteotomy can correct this condition. It takes pressure off the damaged side by wedging open the upper part of the tibia to reconfigure the knee joint and shifts weight away from the damaged or worn tissue and on the healthier tissue.

To find out if one of these procedures is right for you, contact Dr. Howard today.