Author:Mr Oliver Eaton BSc (Hons), PG.Cert – Orthopaedic Specialist Reviewed by:Mr William Sharples BSc (Hons) – Pain Management Expert Last Updated: September 2025
In this article, you will find out everything that you need to know about a lump on the knee and the most effective ways to treat it, including an advanced treatment called Prolotherapy.
A lump over the knee joint can result from chronic inflammation (like arthritis), joint damage, infection, trauma, cysts, or even tumors. Lumps may be soft or hard, painful or painless, and can grow quickly or remain unchanged for long periods. Some lumps are caused by blood clots (hematoma), cysts (like Baker’s cyst), or tumors (benign or malignant). Accurate diagnosis is essential for effective treatment.
What Does a Knee Lump Feel Like?
Lumps may feel bruised, firm, or warm, and can cause pain, redness, or instability. Hard lumps may distort the knee and affect walking. Inflammatory lumps are often red and warm. Imaging (X-ray, ultrasound) and physical exams help determine the cause. If you notice a persistent or painful lump, consult a healthcare professional for assessment.
Causes of Knee Lump
Bursitis: Inflammation of the bursa, often from prolonged kneeling, causing a bulge on the kneecap.1
Gout: Uric acid crystal buildup causes painful swelling and bumps.
Rheumatoid arthritis: Autoimmune inflammation can cause nodules or lumps.2
Osteoarthritis: Cartilage wear and ligament damage can cause swelling and lumps.
Benign tumors: Hard, stiff lumps like fibromas may develop from connective tissue.
Ligament injuries: ACL damage can cause ganglion cysts; meniscus tears can also cause lumps.
Infections: Boils or abscesses may form as lumps.
Cysts: Fluid-filled sacs, such as Baker’s cyst, often appear behind the knee.
Trauma: Hematomas from injury or bug bites.
Types of Knee Lumps
Warts
Small, rough growths caused by HPV, often in clusters. More common in children and those with weakened immunity.3
Synovial Chondromatosis
Joint swelling and pain from abnormal synovium growth, often confused with arthritis.
Skin Cyst
Fluid, air, or fat-filled sacs under the skin, common in adults and those with acne.
Dermatofibroma
Harmless, mole-like growths, often after minor injury, usually on the legs.
Baker’s Cyst (Popliteal Cyst)
Fluid-filled swelling behind the knee, causing tightness and pain, especially
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when flexing or extending the knee. Treating the underlying cause, such as arthritis, often resolves the cyst.4
Anterior Cruciate Ligament (ACL) Cyst
Also called ACL ganglion cyst, these develop from irritation or trauma to the ACL. Symptoms include pain, locking, reduced extension, and clicking. Treatment may involve aspiration, surgery, or physical therapy.
Meniscal Cysts
Caused by synovial fluid leaking from a meniscus tear, these cysts can cause swelling and pain. If untreated, they may erode nearby bone.
Medical Care and Treatment
Apply ice packs for 10–20 minutes at a time, then switch to heat after three days.
Elevate the leg above heart level to reduce swelling.
Rest and avoid activities that worsen pain.
Take medications as prescribed; over-the-counter pain relievers like acetaminophen or ibuprofen may help.
Compression wraps can reduce inflammation.
Physical therapy can improve strength and mobility, especially for cysts or after injury.
Steroid medications or injections may be used for severe inflammation.5
Always consult your doctor if you suspect a blood clot or if swelling does not improve.
Prolotherapy
In recent years, Prolotherapy has built its reputation within the medical community for its clinically proven ability to treat the root cause of Lump on knee.
Published research has proven its pain-relieving, anti-inflammatory, and regenerative benefits.
Prolotherapy involves injecting a natural regenerative solution with tiny needles, stimulating collagen production to repair structures in and around the knee.
As prolotherapy treats the root cause of Lump on knee, it is considered a permanent fix, preventing symptoms from returning.
Disclaimer: The information provided in this section is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Prolotherapy may not be suitable for everyone, and outcomes can vary. Always seek the guidance of a qualified healthcare professional regarding your specific medical condition or treatment options. Never disregard professional medical advice or delay seeking it because of information you have read here.
Surgery
Surgery is rarely needed but may be advised for severe knee damage, persistent cysts, or if the lump is caused by a tumor.
Some cysts can be drained without surgery, but significant injuries may require surgical repair.
Treating the underlying cause often resolves the lump without surgery.
Conclusion
A lump on the knee can result from various causes, from benign cysts to more serious conditions. Early diagnosis and appropriate treatment are key. If you notice a persistent, painful, or growing lump, consult a healthcare provider for evaluation and management.
FAQs
What can a lump on your knee mean?
A knee lump can be due to chronic inflammation, joint damage, cysts, infection, or tumors. Proper diagnosis is essential.
Is knee bursitis a hard lump?
Bursitis usually causes a soft, squishy lump, but it can feel stiff and painful. Treatment includes medication, physical therapy, and lifestyle changes.
What do Baker’s cysts look like?
A Baker’s cyst is a fluid-filled bulge behind the knee, causing tightness and pain, especially with movement.
How do you reduce swelling on the side of your knee?
Use anti-inflammatory medications, ice, elevation, and rest. If swelling persists, see your doctor.
What is the lump on the outside of my knee?
It may be a meniscal cyst, which forms from fluid leaking after a meniscus tear.
What is a housemaid’s knee?
Housemaid’s knee is prepatellar bursitis, a painful swelling in front of the kneecap.6
Does fluid on the knee go away by itself?
Sometimes, but not always. Treating the underlying cause is key. Persistent swelling should be evaluated by a doctor.
Contact ProHealth Clinic Today for Your FREE 15-Minute Discovery Call
Don’t let Lump on knee control your life any longer. Join the thousands of patients who have found lasting relief through prolotherapy at ProHealth Clinic.
Our Clinic Locations London: 104 Harley Street, Marylebone, W1G 7JD Manchester: The Hadley Clinic, 64 Bridge Street, M3 3BN Bedford: The Village Medical Centre, Kingswood Way, MK40 4GH
All clinics offer the same award-winning prolotherapy treatment with convenient appointment times, including evenings and weekends.
Author Bio
Having performed over 10,000 procedures, Mr Oliver Eaton is one of the UK’s leading practitioners in the field of treating Lump on knee, with patients travelling to see him from across the UK, Europe, and the Middle East.
With over 12 years of clinical experience, Oliver is dedicated to helping patients understand their symptoms associated with Lump on knee and providing effective treatment options to alleviate them.
He qualified in Prolozone Therapy and Prolotherapy in America with the American Academy of Ozonotherapy. He continued on to complete further qualifications at the Royal Society of Medicine, Charing Cross Hospital in London, Keele University’s Anatomy & Surgical Training Centre, and the medical department of Heidelberg University in Germany.
Over the years he has had the privilege of treating many elite-level athletes, including both Olympic and Commonwealth medallists.
Gross, G., Pfister, H., Hagedorn, M., & Gissmann, L. (1982). Correlation between Human Papillomavirus (HPV) Type and Histology of Warts. Journal of Investigative Dermatology, 78(2), 160–164. https://doi.org/10.1111/1523-1747.ep12506324
Kruse, D. W. (2008). Intraarticular cortisone injection for osteoarthritis of the hip. Is it effective? Is it safe? Current Reviews in Musculoskeletal Medicine, 1(3-4), 227–233. https://doi.org/10.1007/s12178-008-9029-0
Disclaimer: This article is for informational purposes only and does not substitute for professional medical advice. Always consult your healthcare provider before making treatment decisions.
