Articular Cartilage and Damage to the Knee surfaces – the relevance for cartilage repair
Articular cartilage is the bearing surface on the ends of the bones that allows smooth and easy movement of the knee joint. The joint is enclosed by a capsule rather like a rubber gaiter around an engineering joint and the lubrication is provided by slightly oily fluid called synovial fluid. This makes the surface very slippery but any damage to the surface after injury increases the friction and can lead to catching symptoms and pain in the knee as the joint surfaces move on each other.
The other form of cartilage is the meniscus which is the protective shim between the bones acting as a shock absorber. The MACI procedure for cartilage repair rebuilds the joint surface articular cartilage and not the meniscus (footballer’s cartilage).
The two main moving parts of the knee are between the thigh bone and the shin bone (femur and tibia) and between the kneecap and the front of the thigh bone (patella and trochlea). The first part takes load and forces when walking and landing and the second part takes load on squatting, standing up and activities such as going up and down stairs. Understanding which parts of the joint are loaded in which movements is key to helping the rehabilitation process while the new surface heals.
When damaged articular cartilage does not have the ability to heal itself and untreated defects can cause progressive damage to the joint surface leading to an increased risk of developing osteoarthritis. In addition the symptoms of pain, swelling and limitation of activities can gradually become more intrusive.