Chondromalacia simply means “diseased cartilage”. With this we do not mean the popular “cartilage” that would be called “meniscus” in medical terms.
This piece of connective tissue in the knee functions as a shock absorber beween the lower end of the thigh bone (called femur) and the upper end of the lower leg bone (called tibia). We are actually talking about the coating of a shiny hard material, called “hyaline cartilage”, directly at the end of the tibia and at the end of the femur that is located within the joint.
In the case of the knee joint there is the meniscus between these two surfaces, which protects this weight bearing joint from pressure damage of the hyaline cartilage surfaces of the tibia and the femur. The patella (knee cap) forms also part of the knee joint and has a shiny hyaline cartilage surface on the inside of the knee joint.
This rubs directly on the front part of the lower femoral bone and is often affected with chondromalacia as part of the “patello-femoral syndrome”. This is an important cause of knee pain, which is a common symptom dealt with under this link. There are four stages of chondromalacia that have evolved by observing serial arthroscopies of knee joints first, but have since been found to be present in all joints that have hyaline cartilage as part of the joint surfaces.
Classification of chondromalacia
Grade I : swelling of the superficial layer of hyaline cartilage with breakdown of the network of collagen fibers
Grade II : fibrillated cartilage with surface breaks that extend to the middle layer of the hyaline cartilage
Grade III : breaks in the hyaline cartilage extend to the deepest layer, almost to the depth of the subchondral bone
Grade IV : destruction of the hyaline cartilage with exposure of subchondral bone, indistinguishable from degenerative joint disease (osteoarthritis)
This type of classification has been useful in the past when studies from one center were compared with another or when serial arthroscopies were done in the same patient over a longer period of time. But since then it has been noticed that this classification system is useful also to describe the degree of chondromalacia.
It seems to get more and more accepted that these changes, which can be seen during arthroscopy, are also documenting how far along the degenerative pathway a patient’s joint surface has developed. There is no question that grade IV chondromalacia is synonymous with established osteoarthritis (or degenerative arthritis, how it is now called). There is no general agreement yet with regard to the earlier changes of chondromalacia, whether or not to call them “degenerative” or simply “normal aging phenomena”, although a majority likely would call a grade III chondromalacia as an early degenerative change of the affected joint.
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