The Illustrative Biomechanics of a Chondral Injury

A chondral lesion can occur due to various reasons like trauma, degeneration, pathologies like osteochondritis dissecans (OCD) or a vascular insult. While most of the traumatic lesions are due to the impact of an acute abnormal biomechanical force on the chondral or the osteochondral surface, chronic degenerative lesions occur due to a gradual alteration of the biomechanics over the years. It is the type, force, direction and the repetitions of the load that determine whether the abnormal biomechanics will cause chondral injury or not. While it is not true that there will be abnormal biomechanics behind every cartilage lesion, every abnormal biomechanics will indeed put abnormal loads on the articular surface. Pathologies like OCD and vascular causes may not have abnormal biomechanics all the time. The purpose of this chapter is to discuss some of the abnormal biomechanics that imparts abnormal loads on the articular surfaces of the knee, resulting in a chondral damage. The chapter should open up a thought process in a cartilage surgeon’s mind to understand the importance of the abnormal biomechanics vis-a-vis a chondral lesion.