Articular cartilage injury on a weight-bearing part of the femoral condyle.
Articular cartilage injury in the knee
The knee is particularly vulnerable to articular cartilage damage, because of falls and direct blows during sporting activities.
Damage may range from a softening of the cartilage (chondromalacia), to a full thickness lesion (chondral defect), and a chunk of material may even be knocked off into the joint cavity (loose body).
"Cartilage injuries can occur due to acute trauma or repetitive microtrauma....and this increases dramatically to 10–20 times of bodyweight during sports activities...Most early stage cartilage lesions do not cause a lot of symptoms and disability. However, in later stages, patients present with pain, swelling and mechanical symptoms like locking, catching and crepitus."
How do you regenerate articular cartilage?
Articular cartilage is very different from most of the body's tissues, inasmuch as the cells are far apart from each other, suspended in a matrix without a proper blood supply.
Injury means that the cartilage does not heal well, and even where there is some healing the area tends to produce 'fibrocartilage' rather than true articular cartilage.
This has given rise to a number of special techniques involving bringing in blood components from the deeper sub-chondral layer, and also transferring healthy cells grown in a laboratory or tissue pieces transferred from other healthy areas where they are not so important.
Key regenerative techniques include -
- encouraging stem cells into the damaged area (microfracture, nanofracture, NAMIC, stem cell injections, microfragmented fat injections)
- growing cartilage cells in a laboratory and injecting them back into the damaged area behind a membrane 'curtain', or growing them directly onto a membrane in the laboratory and gluing that into place (ACI, MACI)
- transferring plugs of healthy articular cartilage into the damaged area (mosaicplasty)
Microfracture to allow stem cells and nourishment
Microfracture for articular cartilage repair is a marrow stimulation technique, where holes are picked through the cartilage base plate, to allow blood and cells to track through into the defect.
The procedure may be performed in isolation, or in addition to another cartilage repair procedure.
Nanofracture is a variant of this original procedure, using smaller picks.
Transfer of healthy tissue from less important areas
Procedures like mosaicplasty involve plugs of healthy cartilage being transferred from one area to another
Other relevant links
Chondromalacia, Chondral defect, Loose body, Microfracture, Nanofracture, Autologous chondrocyte implantation (ACI), NAMIC, OATS, Mosaicplasty, MACI - matrix induced autologous chondrocyte implantation, Stem cells, Tissue engineering
Forum discussions
- Does BUPA cover MACI/ACI surgery - Patients discuss whether insurers will pay for cartilage repair procedures.
- exercise after OATS - Patients discuss how to protect the cartilage repair while rehabilitating.