Q A decade ago I had most of the cartilage in my knee removed after a skiing accident. I am planning to run a marathon and am worried my knee won’t be up to the task. I’m reasonably fit, but I haven’t done any running before – am I safe to start?
A A normal knee has two half-moon shaped cartilages between the weight-bearing bones, which help to both cushion and guide the movement of the joint. If the knee is subjected to unusual movement or twisting, the cartilage can tear, resulting in pain and swelling. They may heal, but the majority of damaged cartilages, also known as menisci, require surgery and partial or complete removal to allow pain-free movement after being torn.
The downside of surgery is the loss of the cushioning effect within the joint, so that the ends of the bone, which are covered in another form of cartilage, come into contact with each other. When you run, you land with a force several times your body weight, and this impact is taken directly by your knees.
You may have two knees that are undamaged by their previous trauma, with intact covering cartilage. At the other extreme, you may have two knees in which this cartilage has been badly worn, with the underlying bone exposed. This bone has sensory nerve endings that could be painful.
Provided your knees are not swollen or painful you can start to run. Buy yourself some well-cushioned running shoes that are capable of absorbing the impact of landing, and start to run on a yielding surface, such as a track or trail. Begin by running on alternate days, and see how your knees respond. Swelling and/or pain may mean that you are damaging the knee and need specialist advice. General exhaustion, aches and pains mean that you are just beginning to learn about running.
If you have no problems, increase the time and distance that you run, watching your knees for signs of injury, and applying ice and anti-inflammatory measures if they become painful. Starting with a marathon is rather like the climber who begins by tackling Everest, so do try to keep distances manageable and work your way up the running ladder.
—Dr Patrick Milroy, RW Medical Adviser
