High impact sports such as running are known to be risk factors with respect to knee health, particularly in instances where inappropriate landing of the leg on hard surfaces result in the propagation of shock waves upwards to the knee. Local concentration of the impact shockwaves would lead to progressive degradation of the cartilage lining the articulating surface of the knee.
Cartilage is critical to the proper functioning of the knee, especially in allowing smooth movement of two bones; thereby, enabling mechanical motion of bipedal human on ground. Endowed with a smooth lining capable of withstanding variable load levels, the articular cartilage crucial to human locomotion is nevertheless vulnerable to impact related hairline fractures, which would progressively degrade the conformal cartilage surface.
Running induces loading on the knee, which is largely absorbed by the cartilage; thus, over long periods of time, load related stress on the cartilage would lead to gradual but significant degradation of the load bearing surface essential to smooth transition between running strides. A study reported in the New York Times (Link) highlights contrarian results to the perceived notion that high impact stress sustained in running would lead to inevitable progressive degradation of knee articular cartilage. Specifically, by monitoring the accumulation of proteins that reflects the level of damage sustained by the articular cartilage, the report describes results suggesting that running may be good for overall knee health.
Putting the results into perspective, the knee should be viewed as a holistic system comprising the leg muscles adjoining the articulating knee joint as well as ligaments and tendons. Gradual increase in running intensity helps improves muscle strength and protects overall joint movement necessary to reduce impact stress on the articular cartilage. Reduced stress naturally translates into lower levels of degradation of articular cartilage. Being avascular (i.e., without blood vessels), the articular cartilage lacks regenerative capacity, and is the subject of intense research in the field of tissue engineering due to difficulty in creating suitable biomaterials able to coax chondrocytes (a specific type of cartilage cell) into secreting the biomolecules that hold the cartilage layer together in a conformation suitable for function. Hence, further study is needed to verify the link between running and knee health, which is contrary to the more usual trend of increased stress leading to damage to the articular cartilage.
Category: regenerative medicine,
Tags: articular cartilage, load bearing, ligaments, tissue engineering, regenerative medicine, vertical stress,