Preserving knee cartilage

Could someone advise on what kind of exercise makes the least "wear and tear" on knee cartilage?

Nearly 4 years ago I injured my knee playing tennis, tearing the cartilage and damaging the ligaments. An MRI showed that the cartilage in both knees was very thin. (I am in my 50s). I had physiotherapy and eventually was free of all discomfort without the need for surgery. My consultant said it was important to get back to sport/exercise when I could to strengthen the muscles, however the risk of repeating the injury on the tennis court frightened me, so I decided to find a different form of exercise. I bought an exercise bike, thinking that because I was seated and therefore not putting my weight on my knees, it would be the best way of strengthening the knee muscles without extra wear on the cartilage.

I have been using the bike 4 or 5 times a week, 20 - 30 minutes a time for around 3 years. However, recently I have been feeling aches and twinges in my knees, and I am worried that the cartilage is wearing out. I know that I am probably going to need knee replacements eventually but want to put it off as long as possible. Could the exercise bike be doing more harm than good? Is there another form of exercise which would strengthen the muscles (and keep me fit) without any wear on the cartilage?

Many thanks for any help

Jaycee9973

Dear Jaycee9973

Unfortunately, I dont see what would stop your cartilage from wearing away, once the process has started it usually just continues like a vicious cycle...this has got to do with the properties of the cartilage now. You and your doctors are right, level of activity, age, strength of the muscles will help delay the process a little longer, however i do not agree that rigorous sports is what you need.

if you have been riding a bike for 20-30 minutes daily for three years, this is a repetitive action, its likely to wear the joints out anyway. Remember that if you are not putting any resistance to work on your muscles what you are building is endurance and not strength or power, and again since your muscles have a memory, they probably are adapted to that level of activity anyway.

what you probably need is a specific strengthening program that is short but effective...improving strength is your thigh muscles (front and back), your leg muscles (front and back), also improving your posture is important should there be any deviations that can cause excessive load on aspects of your knee...i.e do you have knocked kees, bow knees, are your feet turned in or out, do you bend at the waist when walking or your back sways backwards, what type of shoes do you normally wear...

When your strength builds up, you can keep it maintained with at least a visit to the gym twice a week...(you do not need to be in the gym everday). You can also work on maintaining the range in the knees by bending and straightening the knee as far as you can on the bed often in the day...10 reps, 4-5 times a day should be enough...

I would suggest working with a trainer or physio for a specific strengthening program with weights that you can gradually progress as strength builds...
if you must use the bike, then start with a medium resistance for a short burst i.e..10 revolutions only (you can do this twice), then gradually progress by increasing intensity...unitil you can manage a high resistance for a short burst (8-10 revolutions at least 4 times)...

In the interim, your cartilage is wearing off because of its inability to regulate its water content effectively, therefore if you have no conficting medical problems some supplements to help improve their properties may be helpful, your GP will be in a better position to advice you on what supplements will be helpful if he feels it is appropriate...

Other aspects you can work on is healthy eating and staying hydrated...your GP can give you some good advice on that

In the meantime I would suggest you lay of any exercises for now...if necessary use a cold pack/warm pack( if your sensation is fine and you have no other conflicting medical history) and wait till you have no twinge or pain even when riding a bike or walking...

If you are worried about keeping fit, there are other ways of doing this, do you swim?