Sudden knee pain: What could the cause be and what should you do?

Why does sudden knee pain occur?

The human knee is a complex joint that is made up of many moving parts and because of its complexity, it is prone to injury, which can lead you to experience sudden knee pain.

The knee is made up of four bones: the femur, tibia, fibula and patella. The bones are connected by ligaments, including the anterior and posterior cruciate ligaments, and the medial and lateral collateral ligaments. Tendons connect the associated muscles to the bones, and bursae and menisci reduce friction and absorb forces. If one or more of these components become damaged through overuse, impact or injury, you may experience sudden knee pain.


sudden knee pain


What can cause sudden knee pain?

Sudden knee pain can be caused by a number of problems. Whilst it may seem logical that a particular ‘event’ such as an injury might be the only reason for sudden knee pain, this is not always the case. Overuse and strain over time can also lead to a point where something within the knee becomes damaged and causes you to experience sudden or sharp pain.

Some of the most common causes of sudden knee pain are summarised below.

Fractures can cause sudden knee pain. The problem is commonly either a tibial plateau fracture, distal femoral fracture, or patellar fracture. The pain is usually sharp and severe and the patient is unable to move the knee. There is usually swelling present. Fractures of the knee can be the result of injuries or falls.


Torn or sprained anterior cruciate ligament (ACL)
When the ACL tears, there is usually a characteristic, loud “pop” heard. The associated sudden knee pain is usually sharp and severe but after some time may subside to a severe ache. Swelling of the knee typically develops within the hour of the injury.

Meniscal injury

Injuries to the menisci (pieces of cartilage in the knee) can be caused both by injury or overuse. A common way people damage their meniscus is with abrupt and forceful twisting of the knee. A grinding or clicking sound can sometimes be heard when the knee is moved. There may or may not be swelling present and locking is common.


Patellar tendonitis (Jumper’s Knee)
Tendonitis is the inflammation of the affected tendons, usually caused by repetitive strain. The pain is usually described as a dull aching with a feeling of tightness. There may be swelling present and difficulty moving the knee.

Runner’s Knee
Runner’s knee is the term used to describe the number of associated issues that can cause pain around or behind the kneecap. Patients often describe throbbing behind the kneecap with these conditions. Popping and grinding sounds are also common.


The onset of gout can cause sudden knee pain. Gout is caused by the build up of uric acid in the body, and commonly affects men in middle age and post-menopausal women. Gout causes intense pain and swelling which usually occurs intermittently for a few days at a time, known as ‘flare-ups’.

When should I seek medical attention for sudden knee pain?

If you cannot put weight on your leg because of severe or sudden knee pain, you should seek immediate medical attention. Similarly, if you have a fever or if your knee is red and hot. If your pain is manageable, you should schedule an appointment with a qualified sports podiatrist promptly so that your condition can be assessed and the appropriate treatment provided. Ignoring pain or pushing through it can exacerbate your injury or cause further damage due to an underlying condition. For your best chance at a timely and successful recovery, do not put off having your sudden knee pain checked by a specialist.

In the meantime, while you wait for your appointment, you can safely rest your sore knee at an elevated height where it sits above the level of your heart (on the couch with a cushion under your knee is an easy way to achieve this). You can apply an ice pack wrapped in a towel for up to 20 minutes at a time at regular intervals throughout the day.

What are the treatment options for sudden knee pain?

The type of treatment that you will require for sudden knee pain will depend entirely on the cause. Once your sports podiatrist has determined the reason for your knee pain, they may recommend a number of treatments, for example:

  • fractures may require splinting or bracing
  • inflammatory conditions such as tendonitis and runner’s knee may require icing, physical therapy, footwear modifications or strapping / orthotics
  • gout will require dietary changes / medication
  • cartilage and ligament tears may require anything from rest and physical therapy through to surgery.

Please note that the information detailed in the article above regarding sudden knee pain is intended to be educational only. It is not intended, nor should it be taken as general medical advice. If you experience sudden knee pain, you should make an appointment with a qualified sports podiatrist as soon as possible so that they can make an accurate diagnosis and formulate an individualised treatment plan. Appointments can be made online at or by calling 93883322.

Karl Lockett– sports podiatrist.