Cartilage versus bone: structural and functional differences

Cartilage Repairing Techniques

Both cartilage and bone are critical components of the human skeleton although cartilage is more flexible and resistant to breakage than bone. Both bone and cartilage are capable of growth and remodeling as they are living tissues but cartilage has generally proven to be more challenging to repair than bone until recently. One of the most common methods of cartilage repair is shaving or debridement in which the surgeon uses an arthroscope inserted into the knee through a small incision to shaves and smooth cartilage that has shredded or frayed due to damage and wear. However, shaving is often not a permanent solution as it does not fix underlying problems such as gait abnormalities ("Techniques for repairing knee cartilage," 2007).

For some patients, shaving is not appropriate because the damage has penetrated all the way to the bone. In these cases, the use of microfracture or abrasion is preferred. In this more intensive treatment, "surgeons use arthroscopic tools to scrape the damaged area and create bleeding of the bone. Small holes are then picked into the defect, allowing blood vessels and bone marrow cells to come in contact with the injury. Bone marrow fills the defect, which eventually matures into scar cartilage" ("Techniques for repairing knee cartilage," 2007). Effectively, damage is generated to encourage the cartilage to self-heal. The technique is only used under extreme cases, however, given that 40 to 70% of patients exhibit decreased knee function ("Techniques for repairing knee cartilage," 2007).

Other, more innovative solutions of more recent vintage involve the use of solutions such as autologous chondrocyte implantation (ACI) in which the cells from the injured knee are grown outside in a culture and then re-injected to grow more cartilage. When this is not suitable, osteochondral allograft transplantation may be used in which surgeons "take a plug of cartilage from a cadaver" and use it in a similar fashion ("Techniques for repairing knee cartilage," 2007).