Knee Ligaments
Ligament injuries are one of the most common injuries to the knee and very few players fully recover from the problem.
Who?
Jonny Wilkinson is the latest star to suffer knee ligament damage. Footballers Marc Overmars, Robert Pires, Paul Gascoigne, Alan Shearer, Ronaldo, and Ruud van Nistelrooy have also had knee problems.
How?
Too much strain put on the knee.
It is usually a twisting or turning action which damages the ligaments.
Direct contact of the knee from opponents can also cause damage to the ligaments.
It can also be simple bad luck - England fast bowler Simon Jones twisted his knee after his studs got caught in the turf as he slid to retrieve the ball in the first Ashes Test in Brisbane in 2003.
How many ligaments are there in the knee?
There are four main ligaments in the knee - one on either side and two across the middle.
Gazza's famous knee injury was the Anterior cruciate ligament, which are cross-shaped within the knee-joint.
Return?
You can have a minor pull which heals within a few weeks, or a major pull which takes between one and three months.
If it is completely torn you could be out for a year.
Treatment
Most cases do not require operations, but occasionally people run into major trouble.
The medial ligament is linked to the cartilage so further problems can result.
Physiotherapy is used as the medial ligament, being outside the joint, heals more easily than the internal cruciate ligaments.
Cruciate injuries, however, require surgery to repair the damaged ligament and several hundred such operations are carried out on sports stars each year.