Here we explain the most common causes of knee pain in sport including injuries that occur suddenly (acute knee injuries) from a direct impact, twisting or collision, or can occur gradually over time, often through overuse (known as chronic knee injuries).
On this page:
- Acute knee injuries
- Pain on the outside of the knee
- Pain on the inside of the knee
- Pain at the back of knee
- Pain at the front of knee
- Immediate first aid for knee injuries
- When to see a doctor about my knee pain?
Sudden onset knee joint injuries will usually involve injury to various structures of the knee including ligaments, tendons, cartilage and even bone. Acute injuries involving collisions, twisting or direct impact with another player or an object can damage a number of structures within the joint. Symptoms include sudden acute knee pain, rapid swelling, heat in the joint and bruising.
Some of the most common traumatic knee injuries include:
- Anterior cruciate ligament sprain (torn acl)
- Medial ligament sprain (inside of the knee)
- Lateral ligament sprain (outside of the knee)
- Medial cartilage meniscus injury
Diagnosing an acute knee injury can often be difficult because the knee is so painful and swollen. When the swelling goes down various assessment and diagnosis tests can be done.
Gradual onset knee pain
Knee pain which occurs gradually over time can often just be an inconvenience or a niggle which the athlete lives with. However, if left, these niggles get progressively worse. They can become chronic knee injuries which are often very difficult to treat. The sooner you get a niggling knee injury treated, the better the outcome is likely to be. Overuse is a significant cause of chronic knee pain, however, biomechanical issues such as overpronation of the foot can make an athlete more susceptible to overuse injuries. We have categorised chronic knee pain depending on the location or area of the knee which is injured:
The most common cause of gradual onset pain on the outside of the knee is iliotibial band friction syndrome. The athlete will complain of pain over a bony area on the outside of the knee. Often the pain will come on at a certain point in a run then go away after a period of rest, only to return again once training resumes. Another cause of outside knee pain is injury to the lateral cartilage meniscus. This is a semi-circular disc of cartilage in the knee joint which provides cushioning and support over time it may degenerate and fray or tear.
Gradual onset pain on the inside of the knee is less common than sudden onset injuries causing inner knee pain. One major cause, particularly in older athletes, is osteoarthritis which is wear and tear or degeneration of the joint, especially the thin cartilage protecting the ends of the bones. Symptoms may develop gradually over a period of months or years and include a deep aching pain in the knee with joint stiffness, particularly in the mornings or after a period of inactivity. Other causes include synovial plica irritation, pes anserine bursitis and medial ligament sprain which is usually an acute injury, but can develop through repetitive strain such as kicking a ball with the inside of the foot.
Chronic pain at the back of the knee which develops gradually is likely to be from an overuse injury to one or more tendons, which join muscles to bone. One of the more common causes is Biceps femoris tendonitis, which is inflammation of the tendon of one of the powerful hamstring muscles. Gastrocnemius tendon inflammation occurs at the point where the large calf muscle originates at the back of the knee. Symptoms include pain and stiffness, especially first thing in the morning. A large swelling at the back of the knee could be Baker's cyst.
The two most common causes of pain at the front of the knee are patellofemoral pain and patella tendonitis (Jumper's knee). The patellofemoral joint is the point where the kneecap touches the femur or thigh bone. It is common for the patella to rub on the bone underneath, causing friction, swelling around the patella and pain. Jumper's knee is inflammation (or more likely degeneration) of the patella tendon which joins the kneecap to the tibia (shin bone). Pain is felt at a specific point at the bottom of the patella. Osgood Schlatter's disease commonly affects young children between the ages of 8 and 13 years old and results in pain at the tibial tuberosity or bony bit below the knee at the top of the tibia.
Immediate first aid for knee injuries
All acute and chronic knee injuries should be treated using the P.R.I.C.E. principle (protection, rest, ice, compression & elevation). This should be applied at home for at least the first 2 - 3 days.
Prevention- Protect the knee injury from further damage. Stop training or playing immediately and apply a cold therapy and compression wrap. Where applicable, use a knee support or brace.
Rest - Refrain from exercise and try to reduce the demands of your daily activity to encourage recovery. It not only refers to the prolonged period of time that the athlete will be out of action but also to the immediate period after the injury. An athlete must know when to stop training and allow the injured area to heal otherwise repetitive minor injuries can often result in a more severe injury that keeps the athlete out for much longer.
Ice - The topical application of ice or cold therapy to the area of the knee injury / swelling can assist in reducing the symptoms of pain and inflammation.
Compression - The use of a compression support or compression bandages to the knee can can help reduce swelling.
Elevation - Keeping the knee elevated above heart level whenever possible to help reduce swelling due to the effects of gravity.
Read more on PRICE principles >>>
When should I see a doctor?
The majority of knee injuries, especially the minor ones can be treated at home. However, if you have any of the following symptoms including severe pain, sever swelling, a pop or crack, locking and altered sensation you should seek further medical assistance.
- Severe pain in or around the knee, especially during walking.
- Severe swelling (oedema) in the knee.
- An audible “pop” or “crack” in the knee joint that is painful.
- A “giving way” feeling in the knee during walking or going up/down stairs.
- A feeling when the knee “locks” whilst bending or straightening it.
- Altered sensation in the foot – such as a feeling of “pins and needles” (paresthesia) or a “loss of feeling” (anaesthesia) in the lower leg.
- Unable to complete your normal daily activities after the initial 72 hours.
Further medical assistance can be sought through either your local doctor or a private clinician such as a physiotherapist, sports therapist, osteopath or chiropractor.
In the first instance, if you have followed the P.R.I.C.E principles (see above) and are still unable to walk after 72 hours or still have severe pain that is not subsiding after the first 72 hours you should visit your local A&E department for further assessment. Also, if your knee gives way whilst walking, feels loose (“unstable”) or locks (unable to move the knee due to pain) then you should consult your doctor or visit A&E.
Secondly, if you have applied the P.R.I.C.E principles and still have weakness or knee pain that lasts a long time (more than 2 weeks) or have ongoing discomfort in your knee, you are highly recommended to seek advice from a specialist expert- such as a physiotherapist, sports therapist, osteopath, or chiropractor who can provide you with advice and an appropriate and effective recovery and rehabilitation program.
These exercises will help you to recover from a knee injury and help to prevent re-injury. They can be introduced into the rehabilitation programme as pain allows, and will help you get back to full fitness. By stretching and strengthening the relevant muscles, the knee will be healthier and move easier without any pain.