Common causes of knee pain: from inactivity to overactivity

At the mention of knee pain, many people think of knee injuries due to sports, overuse or the wear and tear of getting older. However, inactivity can also cause knee pain. At both ends of the spectrum, overactivity and inactivity, your knees can suffer. Many people experienced this through the pandemic lockdowns with some exercising less and others exercising more — and so the term ‘pandemic knee’ was coined. 

Here we’ll explore the three most common lifestyle-related causes of knee pain

1. New or more intense activity

Exercise is great for your body, helping with weight loss and improving your heart health. However, a sudden change in the amount or type of exercise that you perform can cause knee injuries. Similarly, a DIY blitz can also damage your knees, especially if it involves lots of squatting or twisting. 

One of the most common knee problems is a torn meniscus, a type of cartilage found in some joints, including your knees. Each knee contains two menisci, which act as cushions between the top of the shinbone and bottom of the thigh bone. They protect the joints as they move and are easily damaged if your knee moves in the wrong way. A torn meniscus can, therefore, be caused by a trivial injury, exercise or activity, including DIY. 

Often patients never know what caused their torn meniscus, just that their knee hurts when it didn’t several weeks ago. There are ways of rehabilitating a knee with a torn meniscus, including physiotherapy. However, if the pain persists or you develop other symptoms, your doctor may recommend surgery to repair or trim the cartilage.

2. A sedentary lifestyle

Whether you have healthy knees or arthritic knees, inactivity can cause a loss of muscle tone. Consequently, when you then engage in any physical activity, such as a trip to the supermarket, you may experience knee pain and/or knee instability. Spending too much time sitting down is an easy way to lose muscle tone. It’s therefore important to take part in regular exercise to strengthen your muscles.

3. Weight gain

Carrying excess body weight places more strain on your knees, which along with your ankles and hips, are the main load-bearing joints of your body. Gaining even just five kilograms of excess weight can have a negative effect on your knees, especially if you already have a pre-existing knee condition, such as arthritis. It is, therefore, important to follow a nutritious, balanced diet and exercise regularly to maintain a healthy weight.

Knee pain and getting older

In addition to these three major lifestyle factors, age has a role to play in knee pain. Many of the underlying causes of knee pain are due to age-related changes in your knee joints, such as wear and tear of the cartilage and bones (knee osteoarthritis). 

When to see a doctor

Knee pain will often go away after a few weeks with the help of pain relief and avoiding activities that worsen your pain. 

If your knee pain still doesn’t improve or it gets worse, visit your GP. They will ask you about your symptoms and medical history, and will examine your knee. They may send you for further tests and if needed, refer you to a physiotherapist or knee surgeon. You may need to have an X-ray or MRI scan.  

In many cases, knee pain will improve with exercises and rehabilitation prescribed by a physiotherapist or pain-relieving injections. If these treatments do not work or they are not suitable in your case, you may need knee surgery. 

Knee surgery

Knee surgery doesn’t always have to be performed using traditional open surgery. Knee arthroscopy is often used to investigate, diagnose and treat knee problems. It is a type of keyhole surgery and therefore uses smaller cuts than open surgery. A thin, telescope-like tube with a camera and a light on the end (an arthroscope) and special surgical instruments are inserted into your knee via small cuts. During a knee arthroscopy, torn cartilage can be repaired or trimmed. 

If your knee joint is worn out eg due to arthritis, your surgeon may recommend a partial or total knee replacement. After your surgery, you will need physiotherapy to strengthen and restore range of movement to your knee.

Author biography

Professor Iain McNamara is a Consultant Orthopaedic Surgeon at Spire Norwich Hospital and NHS Norfolk and Norwich University Hospital (NNUH). He specialises in early and end-stage knee arthritis and its treatment by non-surgical and surgical methods (such as replacement surgery), arthroscopic (keyhole) treatment of cartilage and meniscal problems, and management of kneecap dislocations. He is also an active member of the research community as Lead of the NNUH Orthopaedic Research Unit and Honorary Professor at University of East Anglia, with a focus on surgical and rehabilitation techniques.