Prevalence of Knee Pain
Frequent knee pain affects 1 in 4 people in the USA1 and is reportedly the most common symptom seen in sports medicine and chronic pain clinics across Canada.2 Knee pain affects people from all walks of life, especially as we age.3 It decreases our quality of life and can even lead to physical disabilities.
What is Knee Pain?
Knee pain is pain felt around the knees due to mechanical issues and underlying conditions. Some common knee pain symptoms include:
- Swelling, inflammation and stiffness
- Redness and warmth to the touch
- Weakness or instability
- Popping or crunching noises
- Inability to fully straighten the knee3
Causes of Knee Pain
Knee pain has many different causes, and can be categorized into three types: acute injuries, overuse, and underlying conditions that result in knee pain.
Acute conditions are severe and sudden onset, such as fractures or injuries.4 Acute injuries commonly occur from accidents and sports.5 The anterior cruciate ligament (ACL), which helps connect your shin and thigh bone, is the most commonly injured ligament in the knee5 and affects close to a quarter of a million people in Canada and the USA6 every year. ACL tears often occur as a result of abruptly changing direction and speed (e.g. in sports like basketball3). Another acute injury is patella (kneecap) fractures and while they are quite uncommon, accounting for about 1% of all skeletal fractures,7 they can seriously impair movement. They occur commonly as a result of falls or automobile accidents.3
Overuse of the knee joint due to repetitive activities and prolonged pressure on the knee can lead to injury as well.5 Tendinitis, the inflammation of the tendons, and tendinosis, small tears in the tendons, are common overuse injuries.5 Tendinitis of the patella (kneecap) is one of the most frequent injuries in sports and is characterized by an aching of the knee.8 It is so common it’s referred to as jumper’s knee and is associated with repetitive activities like jumping, climbing, kicking, or running.8 Overuse injuries like pain in the front of the knee (patellofemoral pain syndrome) are also associated with excess weight and other problems in the kneecap.5
Arthritis is the swelling and tenderness of the joints and tends to get worse as we age.9 There are over 100 types3 of arthritis which refer to different conditions and are so common that 1 in 6 Canadians10 have arthritis and approximately 54.4 million11 Americans have been diagnosed. Rheumatoid arthritis, a very common type of arthritis, is an autoimmune disease in which our immune system attacks the membrane that holds our joint parts together, resulting in the destruction of cartilage and bone.9 Osteoarthritis is also a very common degenerative type, causing pain because the cartilage in the knee wears away.12
Common Risk Factors of Knee Pain
Weight: Researchers found that among obese patients, long-term weight loss has significant positive impacts on health-related quality of life, pain reduction, and improvement in mobility for osteoarthritis patients.13
Sedentary Lifestyle: One third of the global population, 15+, doesn’t engage in enough physical activity.14 This lifestyle change can be a risk factor for your knees as underuse of your legs and knee can result in pain and irritation of the cartilage in your knee.15
Previous Injury: Researchers found that having a history of knee injury increased the risk of knee osteoarthritis four-fold.16
Knowing these risk factors can help manage or prevent knee pain. Staying active, properly warming up and strengthening your knee, and close monitoring of your knee if you have had injuries are great ways to get ahead of these risk factors.
Advancements in Knee Pain and Conditions
Medical research in the space of knee pain has been tremendous and researchers have found, and continue to explore ways that they can improve the quality of life for people living with knee pain.
Pain Management & Lifestyle Change
From prescribing ibuprofen17 (e.g. Advil, Motrin, etc.) to alleviate inflammation of the knee to the creation of numbing creams, there are so many ways that scientists have improved how we manage knee pain. Because of continued research in this area, there is evidence that topical creams for arthritis and numbing agents for knee pain overall can help some people find relief, improving their overall day to day quality of life.3 There are also lifestyle changes that can help alleviate knee pain. A simple and helpful option is weight loss as it can decrease the strain17 on the knee joint which can help alleviate pain.13
Surgery is a treatment for knee pain caused by or resulting in more serious symptoms. ACL tears, for example, heal quite poorly on their own.18 ACL reconstruction, the surgery to replace the ACL, has been around for over 100 years, with the first ACL repair reported in 1900.18 Researchers were able to make continual improvements to ACL reconstruction and went from not directly repairing or rebuilding the actual ACL in the 1970s to returning athletes to their sport19 with the innovation of precise placements of tissue grafts20 today. Advances for meniscus (soft tissue) repair have also undergone major advancements.21 By removing only the torn cartilage rather than removing the entire tissue, surgeons are able to slow down the progression of arthritis; a technology that did not exist 30 years ago.21
Advances in surgery, due to research, have the ability to slow progression and improve people’s quality of life. In addition to repairing existing tissue, we now also have the ability to perform partial and total knee replacement surgeries to help with knee pain. Partial and total knee replacements are surgical options to partially or fully resurface damaged bone and cartilage with metal and plastic.22 Total knee replacement was first performed in 1968 and because of the continual research in this area, they are one of the most successful surgeries in all of medicine.23 One study found that 85.2% of participants reported persistent relief of pain, improved physical function, & satisfaction with the result even two to seven years after their total knee replacement surgery.24
Research into knee pain isn’t exclusively focused on just the knee. Our bodies are so interconnected that research into areas concerning the common causes of knee pain (like weight and sports/muscle training), as well as knee function itself, can help manage knee pain and create better long-term solutions for improved quality of life.
Be proactive about your knee health by joining one of our studies below to earn cash and rewards!
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1. Nguyen U-SDT, Zhang Y, Zhu Y, et al. Increasing Prevalence of Knee Pain and Symptomatic Knee Osteoarthritis. Ann Intern Med. 2011;155(11):725-732. doi:10.1059/0003-4819-155-11-201112060-00004
2. ‘A quiet epidemic’: Why so many Canadians experience knee pain. Global News. Accessed June 21, 2021. https://globalnews.ca/news/5764574/bad-knees/
3. Knee pain - Symptoms and causes. Mayo Clinic. Accessed June 21, 2021. https://www.mayoclinic.org/diseases-conditions/knee-pain/symptoms-causes/syc-20350849
4. Acute vs. chronic conditions: MedlinePlus Medical Encyclopedia Image. Accessed June 21, 2021. https://medlineplus.gov/ency/imagepages/18126.htm
5. Acute Knee Injuries. MedSport. Accessed June 21, 2021. https://medsport.med.umich.edu/patient-education/knee-care/acute-knee-injuries/
6. Campbell CJ, Carson JD, Diaconescu ED, et al. Canadian Academy of Sport and Exercise Medicine position statement: Neuromuscular training programs can decrease anterior cruciate ligament injuries in youth soccer players. Clin J Sport Med Off J Can Acad Sport Med. 2014;24(3):263-267. doi:10.1097/JSM.0000000000000068
7. Current concepts review: Fractures of the patella. Accessed June 21, 2021. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4717300/
8. Tiemessen IJ, Kuijer PPF, Hulshof CT, Frings-Dresen MH. Risk factors for developing jumper’s knee in sport and occupation: a review. BMC Res Notes. 2009;2:127. doi:10.1186/1756-0500-2-127
9. Arthritis - Symptoms and causes. Mayo Clinic. Accessed June 21, 2021. https://www.mayoclinic.org/diseases-conditions/arthritis/symptoms-causes/syc-20350772
10. Facts and figures about arthritis in Canada « JointHealthTM monthly | changing arthritis. Accessed June 21, 2021. https://jointhealth.org/programs-jhmonthly-view.cfm?id=47
11. National Statistics | Data and Statistics | Arthritis | CDC. Published October 2, 2018. Accessed June 21, 2021. https://www.cdc.gov/arthritis/data_statistics/national-statistics.html
12. Knee Pain and Problems | Johns Hopkins Medicine. Accessed June 21, 2021. https://www.hopkinsmedicine.org/health/conditions-and-diseases/knee-pain-and-problems
13. Messier SP, Resnik AE, Beavers DP, et al. Intentional Weight Loss for Overweight and Obese Knee Osteoarthritis Patients: Is More Better? Arthritis Care Res. 2018;70(11):1569-1575. doi:10.1002/acr.23608
14. Park JH, Moon JH, Kim HJ, Kong MH, Oh YH. Sedentary Lifestyle: Overview of Updated Evidence of Potential Health Risks. Korean J Fam Med. 2020;41(6):365-373. doi:10.4082/kjfm.20.0165
15. Got Knee Pain? Maybe The Answer Is More Exercise. NPR.org. Accessed June 21, 2021. https://www.npr.org/2011/04/25/135599703/got-joint-pain-maybe-the-answer-is-more-exercise
16. Muthuri SG, McWilliams DF, Doherty M, Zhang W. History of knee injuries and knee osteoarthritis: a meta-analysis of observational studies. Osteoarthritis Cartilage. 2011;19(11):1286-1293. doi:10.1016/j.joca.2011.07.015
17. Knee Arthritis: Knee Replacement & Other Treatments at HSS. Hospital for Special Surgery. Accessed June 21, 2021. https://www.hss.edu/conditions_arthritis-of-the-knee-total-knee-replacement.asp
18. Davarinos N, O’Neill BJ, Curtin W. A Brief History of Anterior Cruciate Ligament Reconstruction. Adv Orthop Surg. 2014;2014:e706042. doi:10.1155/2014/706042
19. ACL Reconstruction: Helps Athletes Return to the Playing Field | Carolina Orthopaedic & Sports Medicine Center | Gastonia, NC. Accessed June 21, 2021. https://www.carolinaorthopaedic.com/acl-reconstruction-helps-athletes-return-playing-field
20. ACL Reconstruction Is Getting Better All The Time. Sideline Sports Doc. Published January 22, 2019. Accessed June 21, 2021. https://www.sidelinesportsdoc.com/acl-reconstruction-is-getting-better-all-the-time/
21. Advances in Meniscus Repair Technology - SOS Med. Accessed June 21, 2021. http://www.sosmed.org/blog/advances-in-meniscus-repair-technology/
22. Unicompartmental Knee Replacement - OrthoInfo - AAOS. Accessed June 21, 2021. https://www.orthoinfo.org/en/treatment/unicompartmental-knee-replacement/
23. Total Knee Replacement - OrthoInfo - AAOS. Accessed June 21, 2021. https://www.orthoinfo.org/en/treatment/total-knee-replacement/
24. Moran CG, Horton TC. Total knee replacement: the joint of the decade. BMJ. 2000;320(7238):820.