Normal healthy cartilage is built for exercise, to include loading bearing exercise such as running. There is good evidence that chondrocytes, the cells that maintain the cartilage matrix, actually grow better in response to pressure- certain chambers (called bioreactors) have been designed to promote cell growth under these conditions.
It is therefore with mixed emotions that I sometimes advise patients to exercise less, or at least to consider a modification of what type of exercise they are performing. This apparent contradiction comes because cartilage that is damaged already is not the same as normal, healthy cartilage. In spite of many advances in cartilage repair, it is just not appropriate to think that any repair is as good as the original.
All patients are encouraged to stay active. One frequent recommendation is to substitute sports with lower stresses.
Advice for professional athletes may be somewhat different than advice for the ordinary athlete or the ordinary person. If someone is getting paid to perform a sport- or, indeed any type of work- it is not uncommon for them to expose themselves to risks that would not normally occur to other people. This is true whether we are talking about an astronaut or a coal miner or an oil rig worker. As a general rule, professional athletes are very protective of their bodies even though they purposely expose themselves to risk; and they understand the consequences of injury. (I am writing this as Tiger Woods has just withdrawn from the US Open due to “leg injuries”.) It is ironic to see that some non professionals readily accept risks that the pros would never consider.
One frequent mistake occurs when the patient erroneously thinks that if the knee feels better it really is better, and the somehow the healing process is ahead of schedule. Everyone wants to believe they are a fast healer. Some take this as a license to avoid rehab, because “I can do it at home”. Well, that seldom works, and it is a great way to undo an expensive procedure.
Any situation that disconnects expectations from reality should be discussed before cartilage repair is attempted. Almost any surgical solution can be subverted by a patient who does not comply with the post-operative rehabilitation plan. It would be better for all concerned for such a person not have surgery. In medical jargon we call this compliance, but what it really means is bad behavior.
The need for post op rehab was advocated many years ago by Dr. Richard Steadman, one of the original advocates of marrow stimulation for cartilage repair. I must confess that at the time I thought it was a bunch of hooey, but now I am a believer; and there is no faith like that of the converted. The originator of total hip replacement, Sir John Charnley, was once quoted as saying that a perfect operation requires no aftercare. Well, either he was wrong, or cartilage surgery is not perfect, or both.