Why Does Inner Knee Pain Occur When Bending the Knee?

Reviewed by Garrett Kneese, MD, MPH

Family Medicine

Inner knee pain when bending can happen because the tissues and nerves on the inside of the knee get stressed from repeated bending or due to wear and tear, such as in osteoarthritis or saphenous neuritis.

Explanation

When you bend your knee, several parts—like cartilage, ligaments, and nerves—work together. Studies show that doing lots of bending can lead to tiny injuries or lesions in the knee joint. Over time, these small injuries may build up, especially if you often perform activities that put extra pressure on your knee. This can lead to arthritis, where the cartilage (the soft cushion in your joint) wears down, causing pain. One study noted that frequent bending might be linked with small spots of damage seen on imaging. Another possible cause is saphenous neuritis, which is when the saphenous nerve on the inner side of the knee gets irritated. This irritation can also feel painful when bending the knee. So, both the wearing out of the joint tissues (as seen in osteoarthritis) and nerve irritation can lead to inner knee pain when you bend your knee.

(References)

Virayavanich W, Alizai H, Baum T, Nardo L, Nevitt MC, Lynch JA, McCulloch CE, Link TM. Association of frequent knee bending activity with focal knee lesions detected with 3T magnetic resonance imaging: data from the osteoarthritis initiative. Arthritis Care Res (Hoboken). 2013 Sep;65(9):1441-8. doi: 10.1002/acr.22017. PMID: 23554229; PMCID: PMC4118638.
Morganti CM, McFarland EG, Cosgarea AJ. Saphenous neuritis: a poorly understood cause of medial knee pain. J Am Acad Orthop Surg. 2002 Mar-Apr;10(2):130-7. doi: 10.5435/00124635-200203000-00008. PMID: 11929207.
Updated 2023 Jun 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: [https://www.ncbi.nlm.nih.gov/books/NBK507884/
Berteau JP. Knee Pain from Osteoarthritis: Pathogenesis, Risk Factors, and Recent Evidence on Physical Therapy Interventions. J Clin Med. 2022 Jun 7;11(12):3252. doi: 10.3390/jcm11123252. PMID: 35743322; PMCID: PMC9224572.

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