Biomechanics is a branch of medicine that evaluates loads and stresses on a joint. The manner in which a joint is loaded will have direct effect on the health of the cartilage that covers the end of the bone in a moving weightbearing joint. Abnormal loads can lead to cartilage degeneration and subsequent osteoarthritis. Several factors can influence the way a load or stress is applied to a joint. Increase in body weight significantly above ideal puts increased stress on the cartilage and even in the face of normal ligaments and muscles can overload the cartilage. Ligament injury leading to abnormal motion and instability can also cause increased loads to be placed on that joint and subsequent arthritis. Weakened muscles can lead to decrease shock absorbing function about a joint and therefore increase the risk of osteoarthritis. All of these factors can lead to premature failure of the cartilage in a joint and subsequent osteoarthritis. After a knee has undergone knee replacement for the treatment of osteoarthritis there are several factors that can influence the longevity of that joint replacement. These include the surgical technique used and if the surgeon properly restores the alignment and implant position better results can be anticipated. The design of the implant can also influence the amount of stress that the artificial joint sees and there are variations and various implants that will influence longevity and function. There are many things that you as a patient can do to avoid the onset of osteoarthritis, such as maintaining a more normal weight, avoiding significant ligament injury, and if this occurs having this repaired and maintaining the strength of the muscles crossing that joint to improve the shock absorbing aspects of the soft tissue about the joint. Our job, as orthopedic surgeons, is to restore alignment and implant position when performing a joint replacement surgery. The patient should do everything within their power to avoid joint degeneration so as to hopefully avoid undergoing surgical intervention in the future. If this becomes necessary there are many techniques and implants available to satisfactorily restore function to the damaged joint.