“I could talk for days about knees,” says physiotherapist Patricia Collins. “After backs, they are the most common area we treat.” According to a recent paper in the British Medical Journal, 41% of sports injuries are knee-related.

But just because knee issues are common, that doesn’t mean we should ignore them and soldier on. These knobbly little joints bear a heavy load, and problems and solutions can take some untangling. “Not only does the knee have the two major leg bones, the femur and the tibia,” says Bhanu Ramaswamy, physio and visiting fellow at Sheffield Hallam University, “but you’ve got the kneecap, cartilage, tendons and ligaments, and any changes in those will make a knee prone to becoming more stiff or inflamed.”

Here are some of the most common problems – and ways to tackle them.

Tendon issues

Tendons usually attach muscle to bone but the most commonly pranged one in the knee is the stretch of patellar tendon that connects the shin bone (AKA tibia) to the kneecap on its way to the quad muscles at the front of your thighs. “You hear of jumper’s knee,” says Collins, “which is usually seen in sports like basketball, running or football.” (Basically, any high-impact sport where there’s jumping and landing on hard surfaces, and the patellar is working with the quad to extend the leg to jump or kick.) The lower area behind the kneecap will feel tender, and it can be painful walking, running, jumping and straightening and bending the leg. To treat the problem, says Collins, “we keep people working through recovery, because tendons don’t like rest”. She often sees clients who have completely rested their knee until the pain subsided, only to return to running to find it is even worse.

Runner’s knee

It is often assumed that running wears out the knees and raises arthritis risk, but Collins says: “There is no evidence to prove this whatsoever.” Runners tend to be lighter, therefore reducing the lifetime loads on their knees, but it is still important to warm up properly and heed any twinges. Collins’s motto is: “Don’t push into pain,” and this is certainly the case for runner’s knee, perhaps the best-known tendon injury. Otherwise known as iliotibial (IT) band friction syndrome, this affects the tendon to the outer side of the knee, resulting in a sharp pain in the kneecap. “This is one where we say: ‘Don’t run,’” says Collins.

Symptoms usually appear after running or even hiking downhill, or with longer runs – in the last month or so of marathon training perhaps – that increase friction in the area. “The IT band is like a leathery tissue that attaches into the side of the femur and there’s a bursa there – a fluid-filled sack that helps reduce friction.” But overuse can inflame the bursa.

“It does go away eventually,” Collins says, “but it can be a horrible pain and take people out of running for months.” First-line treatment is physio-prescribed exercise, and rest from running.

Torn ligaments

Ligaments attach bone to bone and there are four big ones at the knee joint – two “cruciates” and two “collaterals”, all connecting the thigh bone to the shin bone. “Some of those, if they tear, need surgery,” says Collins, “but some will heal on their own. Others will need bracing and medical management.” But you’re unlikely to have torn a ligament unless your knee has had an obvious trauma from an accident such as a bad fall, or your foot has got stuck and the leg has twisted. To identify a torn ligament, Collins would first ask: “Was there a big swelling, because that may indicate a big injury, bleeding into the joint [called a haemarthrosis] and so on. And is the knee giving way or not supporting your weight? That’s telling us you quite possibly need to see a consultant, and imaging.”

Cartilage injuries

Cartilage is a smooth connective tissue that protects joints. “You’ve got cartilage that covers the bones,” says Collins, “but then you’ve got the semilunar-shaped fibrocartilage called the meniscus that sits in between the thigh and shin bones for shock absorption.” This can get sore from heavy usage, and might feel a bit tender getting out of the car, or stop you squatting and kneeling, and needs time with less heavy usage to recover. “Then it’ll be fine,” says Collins.

If your knee joint is locking, says Collins, and you’re having to physically move it with your hands, that could imply a torn meniscus. To check, Collins would have a client squat down to the floor (heels up). “If they’re lopsided and can’t fully bend at the end-of-range section, that’ll be the cartilage – but you can do things to improve that.” On the spectrum of cartilage injury, a tear would again be from a twisting or trauma that you might see if you do motocross, play rugby, or ski, as opposed to a nagging pain that slowly emerges over time.

As with most knee issues, rehab involves what Collins calls “a graded return to activity, getting things mobile, getting them strong, and, if you’re a runner, lengthening and strengthening the calves.

“The calf attaches above the femur, so it’s above the knee joint,” she says. Standing on the edge of a step and lowering your heels is a key remedial move, sometimes with weights – “we call it heavy-slow training,” says Collins.

Plyometrics work is also crucial in managing cartilage injury, which means reviewing how we jump and land. One exercise to improve this is called the pogo. “Your feet are flat, at 90 degrees [from the legs], and you’re jumping. If you look at the Instagram account for @TheIrishPhysio, he has lots of great exercises like this for runners.”

In some milder cases of cartilage injury, a thinning occurs that makes it more fragile and prone to micro-tears. Collins visualises it as fraying carpet. “Just listen to the symptoms,” she says. “Respond to them, don’t aggravate them any more than necessary, but get your strength back up, and it can and should settle down. It can take months, though.”

Fat pad irritation

This is a common culprit in anterior, or front-of-knee, pain, affecting soft tissue under the kneecap. “You may see a puffiness below the kneecap,” says Collins. This is often caused by the load on the joint being more than it can handle (or a direct blow to the knee). “Maybe someone sits at a desk and their muscles are weak and they are overweight. They will get the same kind of pain as someone who is lighter and a long-distance runner but hasn’t done strength work.”

Preventing injury

And what about preventing all these injuries? Collins says we should instead be talking about reducing risk, “because you often can’t prevent injuries – they can just be bad luck. Your shoes are suddenly a bit worn, and you just push it that last 500 metres or mile or whatever.” Here’s how to reduce that risk, then.

Strength and conditioning
The recommendation is usually some variety of squats, lunges and deadlifts. “With all those movements,” Collins says, “if we can do them well, and perform them regularly, we’re less likely to get injured.” These tackle the glutes, hamstrings, quads, calves, hip flexors and abdominals to boost “stability, power and endurance”. Women experience more anterior knee pain and are eight times more likely to tear their cruciate ligament, says Collins. “Female knees are not great at absorbing shock, so when we jump and land when we run, we are a lot more at risk of knee pain than men.” This makes strengthening exercises even more important. “It always comes back to looking at how someone moves, and giving them exercises, and the tools to try to get themselves strong and maintain that.”

Rather than starting with deep squats, Ramaswamy says, intensity can be built, “gently, over time, lowering your body, eventually adding weights or holding the squat position for longer. Then change into lunges, so it’s one leg taking all your weight, instead of two.”

Rest
“Listen to pain,” says Collins. “If you overdo it one day, that’s OK if it’s grumbling,” as long as the next day you take it easier. Pay attention to your fatigue, how well you slept and your stress levels, as well as how much you are hurting. All of these can increase injury risk or slow recovery. As far as pain goes, try rating it out of 10. “Beyond a three, you shouldn’t be pushing into pain,” she says. “If you’re getting sore and not recovering, give yourself a 48-hour break.” The NHS Couch to 5k programme can help ease overeager runners back gently.

Avoid aggravating moves
If your knees aren’t happy, “breaststroke is probably one of the most irritating things because of the rotation to the knee and pressure pushing through the water,” says Collins. Ditto running, or long steep walks, downhill, “because you are controlling your body weight against gravity. The quad muscles are working in a lengthened way, which is just harder,” she says.

Maintain a healthy weight
“If you lose half a stone of weight, that’s equivalent to losing two and a half stone of pressure through your knees when you go up and down stairs because of the angles and the point of impact,” says Collins.

Seek professional help
“If a pain builds steadily over time, then there is something wrong that you need to get checked,” says Ramaswamy. “It doesn’t always need an X-ray, because they don’t always show the problem, but it does need a musculoskeletal specialist.” The NHS has boosted its physio workforce, with many attached to GP surgeries. “The knee is a little at the behest of what’s happening at the hip and the ankle, like if you’ve got flat feet and your ankle pulls in, that affects how your knee operates.” Only a specialist can spot these root causes.

Stretch and lubricate
If your knees are stiff and sore at the end of a day’s activities, Ramaswamy recommends gentle stretching, as well as “sitting down and straightening and bending the leg with no weight on it”. This helps the synovial fluid, which lubricates and cushions the joint, to work through the knee.

Use pain relief
Nagging pain and the anticipation of it exacerbates the situation. “There is no reason that you shouldn’t take painkillers over a couple of days, unless you’re allergic to them,” says Ramaswamy. “You want your brain to stop being on alert for the pain, which beds down the pathways that might make you more cautious about moving. The problem with cautious movement is that you’re then altering your natural movement mechanism.” She’s talking about over-the-counter products such as paracetamol and ibuprofen. The latter, in the NSAID category, is anti-inflammatory as well as painkilling, although, says Ramaswamy, “not everyone has swelling and the issue is not always inflammation”. NSAIDs aren’t recommended for those with health conditions such as kidney disease or who have had stomach ulcers, so it’s not one size fits all. The charity Versus Arthritis has more information.

Protect your kneecaps
Kneeling pads are a necessity rather than a luxury for activities such as gardening, says Ramaswamy, “where you’re putting pressure directly on the point of the knee”. She has been pleased to see that trousers for plumbers and manual labourers have inbuilt knee pads these days, “so your kneecap isn’t bearing the brunt of your weight, because that in itself can lead to arthritic changes”.

Genetics play a large part, too, in developing arthritic changes. You can’t reverse these, says Ramaswamy, “but you can manage them, which is why we’re trying to get people to stay fit and active and catch it quickly”. Less weight-bearing exercise such as cycling and exercising in water can be good (avoiding breaststroke kicks if they trigger pain). Walking is fantastic, too. “You’ve just got to watch that when you’re tired that you don’t sag from the hips,” says Ramaswamy. “That will affect weight going through the knees. Draw yourself up tall and take long, confident strides, even if you’re in company and talking.”