There are four bones being held together by four main ligaments in a knee joint which is separated by cartilage which acts as cushioning between the bones. A knee ligament injury can either be minor by being stretched (sprained) or torn (ruptured).
A ligament rupture can be partial with only some of the ligament fibres being torn or complete where the ligament has torn all the way through resulting in pain, swelling, bruising and tenderness causing reduced movement of the knee joint. A knee can become unstable after a ligament injury and in severe cases a knee reconstruction is needed to graft and re attach a new ligament to stabilise the joint and prevent further dislocation.
Depending on the severity of the injury, a rider can expect to face 3-6 months off the bike after undergoing surgery with the worst case we have heard of being 11 months off the bike. Months of physiotherapy and rehabilitation are needed before the joint is back to somewhat 100% and the graft has become truly strong. Eager riders may rush to get back on the bike as their knee feels fine and they want to ride, but within the first 6 months the graft is still weak and the chances of injuring the joint again are quite high.
Prevention is better than a cure:
Even the most expensive knee brace on the market is cheaper than the MRI you will need if you damage your knee ligaments. Luckily we Aussies have a decent health system, but the idea of 6 months off the bike (among other setbacks like not being able to work or hit the dance floor) should be enough to make anyone want to invest in a set.