Knee Pain: Causes, Treatment and When to See a Doctor

What causes knee pain?

Knee pain is common. It can start suddenly, after an injury, or build up over time, and it becomes more common as you get older.¹ Where you feel it is a first clue:¹

• Front of the knee. Often pain around the kneecap, bursitis or arthritis
• Sides of the knee. Often an injury or arthritis
• Back of the knee. Arthritis, or a fluid-filled swelling called a Baker’s cyst

Common causes

Osteoarthritis

The most common cause of ongoing knee pain in middle age and beyond. It brings pain with activity, stiffness after rest and sometimes swelling. See knee osteoarthritis.

Pain around the kneecap

Called patellofemoral pain, this is felt at the front of the knee, where the kneecap runs over the end of the thigh bone.¹ It is typically worse with stairs, squatting and sitting for long periods. It is very common: a systematic review put the number of people affected each year at about one in five.²

Ligament and cartilage injuries

Sudden twists, awkward landings and collisions can sprain or tear the ligaments that hold the knee together, or tear a meniscus, one of the two cartilage pads that cushion the joint. A torn ligament typically causes swelling, pain and a knee that feels loose. A torn meniscus can cause swelling, pain and trouble straightening the leg. Meniscus tears also develop gradually with age.³

Bursitis

Swelling of one of the small fluid-filled sacs that cushion the knee, often from a lot of kneeling.^1,4

Gout and infection

Gout can cause sudden, severe pain and swelling in a knee. See gout. An infected joint looks similar and is an emergency.¹

Do I need a scan?

Often not. Your doctor can usually work out the cause from your story and an examination.¹

Scans also find things that aren’t causing the problem. A review of 63 studies looked at MRI scans of more than 5,000 knees that had no pain and no history of injury. In adults aged 40 and over, 19 per cent had a meniscus tear and 43 per cent had cartilage damage.⁵ A finding on a scan only matters if it fits your symptoms.

After a fall or a blow to the knee, doctors use a short checklist to decide who needs an X-ray. In pooled studies of more than 4,000 adults, it picked up 98.5 per cent of fractures.⁶

How to treat knee pain

After an injury

• Avoid putting weight on the knee
• Use an ice pack for up to 20 minutes every two to three hours
• See your doctor if it hasn’t improved after a few days¹

Exercise

Exercise is the most consistently supported treatment for long-term knee pain.

• For knee osteoarthritis, a Cochrane review of 44 trials found that exercise reduced pain by an average of 12 points on a 100-point scale, and improved function⁷
• For kneecap pain, an international expert panel recommends exercise therapy, especially a combination of hip and knee strengthening⁸

A physiotherapist can set up a program that suits your knee.

Weight loss

Extra body weight puts more load through your knees, and even a small loss can ease pain.¹ In an 18-month trial of overweight adults with knee osteoarthritis, the group who combined diet and exercise lost about 11 per cent of their body weight and had less pain and better function than those who did diet or exercise alone.⁹

Supports

Strapping, a brace or shoe inserts can help some people.¹

Surgery

A torn ligament in a young, active person may need a reconstruction.³ For wear-and-tear problems, the picture has changed. In a Finnish trial, people with a degenerative meniscus tear who had keyhole surgery to trim it did no better over 12 months than people who had a sham operation.¹⁰ An international guideline panel now recommends against keyhole surgery for nearly everyone with degenerative knee disease.¹¹

Knee replacement is a different operation, used for severe arthritis when other treatments haven’t helped.

Is knee pain becoming more common?

It seems so. In a long-running American study, the proportion of people reporting knee pain roughly doubled in women and tripled in men over 20 years. Arthritis seen on X-ray did not increase over the same period, and rising body weight explained only part of the change.¹²

When to get urgent help

Go to an emergency department if:¹

• Your knee is badly swollen or has changed shape
• You have a fever and a red, hot knee
• The pain follows a major injury

When to see a doctor

• You can’t put weight on the knee, or can’t move it¹
• Your knee locks or gives way¹
• The pain is severe, or hasn’t improved after a few days¹
• Knee pain is stopping you from being active

References

1. healthdirect. Knee pain.
2. Smith BE, Selfe J, Thacker D, et al. Incidence and prevalence of patellofemoral pain: A systematic review and meta-analysis. PLoS One. 2018;13(1):e0190892.
3. Better Health Channel (Victorian Government). Knee injuries.
4. healthdirect. Bursitis.
5. Culvenor AG, Øiestad BE, Hart HF, et al. Prevalence of knee osteoarthritis features on magnetic resonance imaging in asymptomatic uninjured adults: a systematic review and meta-analysis. Br J Sports Med. 2019;53(20):1268-1278.
6. Bachmann LM, Haberzeth S, Steurer J, et al. The accuracy of the Ottawa knee rule to rule out knee fractures: a systematic review. Ann Intern Med. 2004;140(2):121-4.
7. Fransen M, McConnell S, Harmer AR, et al. Exercise for osteoarthritis of the knee: a Cochrane systematic review. Br J Sports Med. 2015;49(24):1554-7.
8. Collins NJ, Barton CJ, van Middelkoop M, et al. 2018 Consensus statement on exercise therapy and physical interventions (orthoses, taping and manual therapy) to treat patellofemoral pain: recommendations from the 5th International Patellofemoral Pain Research Retreat, Gold Coast, Australia, 2017. Br J Sports Med. 2018;52(18):1170-1178.
9. Messier SP, Mihalko SL, Legault C, et al. Effects of intensive diet and exercise on knee joint loads, inflammation, and clinical outcomes among overweight and obese adults with knee osteoarthritis: the IDEA randomized clinical trial. JAMA. 2013;310(12):1263-73.
10. Sihvonen R, Paavola M, Malmivaara A, et al. Arthroscopic partial meniscectomy versus sham surgery for a degenerative meniscal tear. N Engl J Med. 2013;369(26):2515-24.
11. Siemieniuk RAC, Harris IA, Agoritsas T, et al. Arthroscopic surgery for degenerative knee arthritis and meniscal tears: a clinical practice guideline. BMJ. 2017;357:j1982.
12. Nguyen US, Zhang Y, Zhu Y, et al. Increasing prevalence of knee pain and symptomatic knee osteoarthritis: survey and cohort data. Ann Intern Med. 2011;155(11):725-32.