Knee Pain When Bending

Knee pain when bending: general information

Knee pain when bending is a common problem, with more than 25% of adults suffering from regular knee pain1. You might have noticed that your knee hurts when you bend it, when you walk down stairs or when you squat. The knee is a complex unit of moving parts, including the thigh bone (femur), the shin bone (tibia), the knee cap (patella), and a number of ligaments, tendons, and cartilage and fluid-filled sacs (bursae), which reduce friction and allow for smooth motion. When one or more of these components become damaged through acute injury or overuse, painful conditions can arise. The treatment for your knee pain when bending will largely depend on the diagnosis.

Knee Pain When Bending

Types of knee pain when bending

Knee pain when bending can be broadly split into two kinds: weight-bearing and non-weight-bearing. With weight-bearing pain, the knee pain when bending occurs when there is weight passing through the knee as you move through the bending motion. This includes situations such as squatting down (as in when you lower your body to sit on a chair) and when you walk up and down stairs. Weight-bearing flexion tends to be more painful due to the added pressure and compression on the structures in the knee. Non-weight-bearing knee pain when bending occurs when there is no weight passing through the knee with the bending motion. An example could be if you are sitting in a chair and simply flexing and extending the knee, or if you are standing and bending the knee off the floor, such as in a kicking motion.

What causes knee pain when bending?

There are a number of conditions that can cause knee pain when bending. The pain may come on suddenly following an injury, or it may develop gradually over time with chronic conditions. The most common causes of knee pain are:

Runner’s Knee (patellofemoral pain syndrome)

Runner’s knee is the broad term used to describe a number of conditions affecting the patella that cause knee pain when bending. The pain tends to occur just below and to the sides of the knee cap. Pain is usually worse when walking downhill. Sometimes a grinding sound can be heard with bending. Runner’s knee can occur as a result of overuse, impact, misalignment of the bones, weak muscles or muscular imbalances, or bio-mechanical problems with the feet.  Chondromalacia patella- a condition that causes the cartilage under the kneecap to break down- can also cause Runner’s knee.

Arthritis of the Knee

‘Arthritis’ refers to the inflammation of a joint. There are different types of arthritis, but osteoarthritis is the most common type that causes knee pain when bending. In patients with osteoarthritis of the knee, the pain is due to excessive friction in the knee, caused by thinning or wear of the cartilage, and the formation of bony lumps inside the joint. Osteoarthritis most commonly affects people that are over 65 years old, but there are many factors other than age that also contribute to the development of the disease, such as genetics, altered biomechanics, and overweight and obesity. The pain is usually worst first thing in the morning or after sitting for a period of time.

Knee Bursitis

Bursitis is the inflammation of the bursae. Bursae are small, fluid-filled sacs that are located between bone and soft structures to reduce friction when moving. In patients with bursitis, the knee pain when bending may be felt in various locations, depending on which bursa is affected. It is caused either by overuse or prolonged pressure / friction on the bursae, impact to the knee from a fall or strike, or excessive friction.

Housemaid’s Knee (prepatellar bursitis)

For people who spend a lot of time kneeling (such as tradesmen), Housemaid’s knee is a common cause of knee pain when bending. It is a condition that describes inflammation of the prepatellar bursa, which is the bursa that is located just below the kneecap at the front of the knee. The pain is generally in the front of the knee and it is common to have quite a large swelling anteriorly.

Meniscal Tear

Meniscal tears are a common cause of knee pain when bending. The meniscus is a thick and strong layer of cartilage that lines the knee joint, providing protection and allowing correct transmission of forces through the joint. If the meniscus becomes torn or frayed, this is known as a meniscal tear. Tears may occur with sudden twisting of the knee with a fixed foot, or through wear and tear. The resulting pain is due to inflammatory processes and reduced cushioning of the knee joint. Torn fragments may become stuck inside the joint, causing further pain and limiting movement. In patients with a meniscal tear, the knee will most likely be swollen and the patient’s movement will likely be restricted. The pain is usually especially bad when bending down or walking up stairs.

Baker’s Cyst

A swollen semimembranosus bursa at the back of the knee is referred to as a Baker’s cyst. This is usually related to arthritis, but it can occur with any condition that causes swelling inside the knee. Patients with a Baker’s cyst tend to experience knee pain when bending and straightening their knee, and a little bulge that feels like a small water balloon can often be felt at the back of the knee.

Other causes of knee pain when bending

Whilst the conditions mentioned above are some of the most common causes of knee pain when bending, some less common causes may include

Treating knee pain when bending

Almost any type of injury or problem with the knee joint and its associated structures can cause knee pain when bending. Your sports podiatrist will be able to recommend the best treatment course for you once a diagnosis has been made. It is imperative that you seek medical attention for a correct diagnosis for your knee pain so that you are not exacerbating the cause of the problem. As a last resort / temporary measure you can proactively manage your knee pain by taking over the counter NSAIDs (non-steroidal anti-inflammatory drugs) such as ibuprofen, applying wrapped ice packs to your knee for 20 minutes at a time, and comfortably elevating your sore knee as you sit, to reduce inflammation and relieve pain.

The information provided regarding knee pain when bending, in the article above is intended for educational purposes only and should not be taken as general advice. If you are experiencing knee pain when bending, you should seek medical attention from a suitably qualified sports podiatrist who will be able to diagnose your condition and devise an individual treatment plan. You can make an appointment online at or by calling 93883322.

Karl Lockettsports podiatrist.

 1 Bunt, C. W., Jonas, C. E., and Chang, J. G., (2018). Knee Pain in Adults and Adolescents: The Initial Evaluation. American Family Physician, 98(9).