Understanding knee pain - part one

The knee is a complex joint.

It’s the largest joint in the human body, made up of two main joints, ligaments, bones and muscles.

The upper and lower bones of the knee are separated by two discs known as 'menisci'.

The bones above and below the knee are connected by a selection of ligaments, tendons and muscles.

Within the joint, the ends of the joint are covered by articular cartilage which absorbs shock and provides a smooth gliding surface for joint movement.

The mechanical complexity of the knee joint allows us to have full movement and mobility in our legs. It also allows us to participate in vigorous exercises that push the limits of the body.

Labelled diagram of the anatomy of a human knee

The causes of knee pain

Knee pain is the second most common cause of chronic pain and can occur in men, women, and children.

Whether your knee pain is new, has occurred suddenly or you have a longer-term injury, it's best to get it assessed by a physiotherapist.

Usually, knee pain is not a sign of anything serious. It can often be treated at home with a program from a physiotherapist.

When analysing and diagnosing knee pain, your physio or treating professional will have to carefully determine which structures are damaged.

Recovery and rehabilitation

The good news is few injuries demand complete immobilisation.

Depending on what is injured or damaged simply requires different management.

Additionally, most injuries benefit from exercise.

Finding out what’s gone wrong in the knee will be vital in optimising your recovery.

You don’t have to give up an active lifestyle, even high impact activities like hiking, tramping, mountain biking or skiing.

Your physiotherapist can help you find a different approach to reduce the load on your knee joint and reduce knee pain.

The science of the knee joint

The knees play a fundamental role in our mobility, they not only carry the weight of our body but also absorb the shock that is caused by walking, running, and jumping.

  • When walking your knees absorb up to 261% of your body weight
  • Walking upstairs they absorb up to 316% of your body weight
  • Walking downstairs they absorb 346% of your body weight

Weight loss can significantly reduce strain on your knees – for every 1kg of weight lost equates to a 4kg reduction in load through the knee joint.

Body Mass Index

Your Body Mass Index (BMI) is a tool used to determine whether you are in a healthy weight range for your height.

According to the Heart Foundation, BMI is a useful measurement for most people over 18 years old. However, it is only an estimate and it doesn’t take into account age, diverse ethnicity, gender and body composition.

It is important to factor in your waist measurement and other existing risk factors.


Under 18.5




Weight category    


Healthy weight range




Under 18.5




Weight category
(People of Asian decent)


Healthy weight range



Lifestyle and occupational factors

Activities like repetitive kneeling, squatting or frequent high impact activities can lead to increased incidences of knee pain.

Muscle weakness and tightness

When your muscles and ligament are unable to meet the psychical demands of your daily activities, the load will be transferred to your joints. This extra load can result in discomfort and pain.

Likewise, knee injuries will cause muscles to weaken. This cycle is why you can still experience knee pain even after you have recovered from your injury.

Working with a physiotherapist can help you to improve function. When you are set up with the correct exercises to rebuild the muscle around the joint, this can greatly reduce the recurrence of knee pain.

Biomechanical issues

Everyone’s bodies are built differently, making some people more disposed to experience knee and joint pain.

Some examples of this include having flat feet or high foot arches, bowed or knocked knees, and leg length differences.

Scientific diagram outlining the impacts of differing foot types, foot alignments and leg alignments

Image source.

Knee pain can be a debilitating condition which impacts your mobility and confidence in daily living.

If you’re experiencing any sort of knee pain whether it’s new or from an existing injury, illness or disability – you can get help from your physiotherapist to get on top of it.

Further reading and resources:

You can book an appointment with an APM Physiotherapist online or in your local area by calling 0800 967 522.

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