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Published on: 5/6/2025

Why Might Knee Pain Occur When Bending the Knee?

Garrett Kneese

Reviewed by Garrett Kneese, MD, MPH

Family Medicine

Knee pain when bending often happens because bending puts pressure on parts of the knee that may already be irritated or inflamed, such as in conditions like anterior knee pain or early osteoarthritis.

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Explanation

When you bend your knee, several parts of the joint work together, including the cartilage under the kneecap, the joint lining, and nearby soft tissues. If any of these parts are irritated or have inflammation, bending the knee can make the pain worse. For example, a condition known as anterior knee pain can cause discomfort when the kneecap is stressed during bending. Also, in early osteoarthritis, the joint tissues may start to break down; repeated stress from bending can lead to more pain. When these tissues are overworked or are suffering from inflammation (known as synovitis), the fluid in your knee might increase, causing further discomfort. It is a bit like having a door hinge that isn’t well-oiled—each time you move it, the wear may cause squeaking or pain. Rest, proper exercise routines, and sometimes physical therapy can often help relieve the symptoms while the joint heals.

(References)

  • Werner S. Anterior knee pain: an update of physical therapy. Knee Surg Sports Traumatol Arthrosc. 2014 Oct;22(10):2286-94. doi: 10.1007/s00167-014-3150-y. Epub 2014 Jul 6. PMID: 24997734.

  • Updated 2023 Jun 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: [https://www.ncbi.nlm.nih.gov/books/NBK507884/

  • Van Ginckel A, Wittoek R, De Mits S, Calders P. Repetitive Knee Bending and Synovitis in Individuals at Risk of and With Knee Osteoarthritis: Data From the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium. Arthritis Care Res (Hoboken). 2019 Oct;71(10):1372-1378. doi: 10.1002/acr.23760. PMID: 30221482; PMCID: PMC6421112.

  • Hensor EM, Dube B, Kingsbury SR, Tennant A, Conaghan PG. Toward a clinical definition of early osteoarthritis: onset of patient-reported knee pain begins on stairs. Data from the osteoarthritis initiative. Arthritis Care Res (Hoboken). 2015 Jan;67(1):40-7. doi: 10.1002/acr.22418. PMID: 25074673; PMCID: PMC4296218.

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