Prevention beats cure; Olympic physiotherapist Mike Callaghan looks at knee damage and how to beat it
Knee pain is a very common type of injury in most sports and unfortunately cycling is no exception. Cyclists can be plagued by various disorders in and around the knee ranging from the very obvious "I've fallen off my bike; what a big bruise I've got!" to the more baffling, "Why on earth is my knee giving me such gyp?"
It's the baffling problems which can have both rider and physiotherapist scratching their heads that are the real bugbear. These injuries can be due to very subtle changes in the rider's style of riding, in the equipment on the bike or in the muscles and ligaments around the knee.
How does the knee work?
The knee joint is actually two joints which work in unison. One is the tibiofemoral joint, directly linking the shin bone (tibia) and thigh bone (femur). This is thought of as the knee joint proper. The other is the patellofemoral joint, which involves the knee cap (patella) and the thigh bone (femur). This distinction is important for cycling. The tibiofemoral joint (knee joint) is not the main area at risk from injury. The problem area is the patellofemoral joint.
Why is the knee cap a problem?
Well, cycling puts large compressive forces behind the knee cap because the revolution of the pedals bends the knee to approximately 111 degrees. The other reason is that the huge quadriceps muscles for which cyclists are famous all meet at the knee cap to form a large tendon (see diagram). Tremendous forces are generated by this muscle group during the downstroke to straighten the knee so there is increased tension within the tendon. Runners have the same problem when they go uphill, but of course they don't run uphill for 70-100 miles in one training run!
How can the knee be damaged?
If someone falls off the bike, the injury is fairly obvious. But along with the usual cuts and grazes other more serious damage has to be checked. There could be a fracture, torn cruciate or collateral ligaments, or torn cartilage (meniscus). The good news is that these types of injury are very rare in cycling compared to football, rugby etc. However, having a swollen knee after a crash is still bad enough and indicates that the knee has taken a good pounding and been irritated.
So it's fairly simple then?
No, not really. A fall may be straightforward to diagnose and solve. But suppose that someone gets a sore knee for no apparent reason. They can't remember a fall, a crash or even the instant that it came on. These are often classed as 'overuse injuries'. The bad news is that cycling causes this type of injury to the knee more than other sport. Cyclists commonly suffer from tendonitis, bursitis, or irritation of the joint. This is where getting experienced, qualified help is important as a lot of medical detective work is needed to find the source of the problem.
How can I overuse my knee?
The three main reasons why overuse injuries occur are poor biomechanics, poor mechanics (the science, not the blokes who clean bikes!) and poor cycling technique. Any of these three areas can cause problems that are hard to detect. This is because the errors may be small in themselves and may not seem significant or noticeable. But a cyclist training 120km per week will bend and straighten the knee about 200,000 times; it's then that the small faults starts to have an effect and cause pain.
A lot of knee trouble in cyclists is not treated properly because the person giving treatment may look only at the knee. They ignore the fact that what happens at the knee and knee cap can often be due to foot position. Simple biomechanics of the foot/ankle has a 'knock-on' effect at the knee joint proper, and at the patellofemoral joint in particular. As we'll see later, it's often a case of 'look after the foot and the knee will look after itself.'
Biomechanical faults - These are problems due to the tissues of the body not functioning correctly, including bones, muscles, tendons and ligaments. Some riders have slight malalignment of the knee cap, which can be measured. Other riders may have tightness of the tendons and soft tissue structures around the knee causing the knee cap to be pulled to one side. The lower back is sometimes a problem too since it may refer pain to the front of the knee, fooling riders into thinking the problem is with the knee when, in fact, it is the back all along.
Mechanical faults - Any minor fault in the cranks, pedals or spindles can cause overuse injury. This is most likely to happen after a crash, but even an unspectacular prang could cause slight twisting of the equipment. This often shows itself days or weeks later with pain in the knee cap area. Some riders get knee cap pain after switching to clipless pedals systems from old fashioned clips and pedals, which allowed a little play between the shoe and pedal. This is why the floating clipless systems were introduced later on, allowing some slight movement of the foot.
Saddle height - is also worth considering when you're getting unexplained knee pain. We know that lowering the saddle causes more knee bend and increases the force going through the quadriceps muscles and tendon; these two in turn will put more pressure on the patellofemoral joint. Experiments in Australia have said that even a small change in saddle height can cause patellofemoral pain. So don't tinker with saddle height just for the sake of it. The moral is: "If it ain't broke, don't fix it."
Cycling technique - More difficult to check as it needs a good coach to advise about position on the bike. Poor technique can lead to biomechanical faults due to lousy foot position on the pedals, poor leg position, sitting skewed on the saddle, or being too stretched out. If these are not corrected, problems can easily occur. Remember that poor technique will mean poor performance and power output as well as injury.
How can I prevent or cure knee problems?
THE SADDLE - Varying the saddle height can relieve some harmful stresses on the knee ligaments. More importantly, if your knee cap is causing trouble it may be wise to raise the saddle slightly. This eases the forces on the patellofemoral joint by stopping the knee from bending too much.
THE PEDAL - If the knee joint is really beginning to bug you, then the pedals should always be checked and adjusted for abnormal play due to faulty plates, spindles etc. Some experts in the USA reckon that this is the most common cause of knee pain, so it's worth spending a lot of time checking your foot position on the pedal.
It's no coincidence that good technique (ie pedalling on the ball of the foot) decreases the stresses across the knee ligaments. Pedalling with the heel nearer to the pedal stops the ankle from moving properly and interferes with the calf muscles. Try it and see! Some people have experimented with special insoles put inside the cycling shoe to correct foot position, but they have found that it only helped during light to moderate cycling and not when the going got tough.
STRETCHING - How many of you really stretch properly? There's no doubt about it, having tight soft tissue structures (especially of the muscles and tendons) has been found to increase the risk of pain around the knee cap. To help ease and prevent this problem, stretching should be done to the calves, quadriceps, hamstrings, and the ilio-tibial band on the outside of the knee and thigh... regularly!
CADENCE - Riding with brisk cadences reduces the force applied, and reduces the stress on your knees. Mashing the pedals while overgeared is a great way to wreck your knees.
AND... There are very sophisticated ways these days of videoing a rider's position, knee alignment, foot placement, saddle position etc. These systems are widely used in the labs in the USA, but are not really available to most cyclists in Great Britain. But don't worry: many knee problems can be solved by checking the body and equipment in a methodical manner, using the kind of information we've given you.