Thanks to the internet, I have a really good picture of what has happened inside my knee. If you’re interested in knees, this is a really good site:
The curved thigh bone (femur) sits on top of two ‘c’ shaped pieces of cartilage (the menisci), which (if the knee was a clock) run round from roughly 12.30-6 o’clock or so and from roughly 6-11.30 o’clock, but in separate compartments – a bit like an incomplete set of spectacles. These stop the femur from rubbing on the flat shin bone (tibia) and absorb a lot of the complex forces of walking, running, jumping. Injuries of the medial (inside) meniscus are more common and complex tears, like I had, are more likely in older people, but may also be to do with the length of time since the injury started and the various things I have done since that I probably should not have, which have likely aggravated it / caused further damage!!
The torn / damaged area has now been completely removed, leaving some ‘shock absorber’ still in place. However I also have deterioration (likely to lead to arthritic pain) in both sides of the knee and also behind the knee cap.
All those years when the joint worked so well, I took it for granted.
Now, when I see people walking with no problems, I want to tell them not to take for granted the little miracle that is their knee!