Guide to Common Reasons Behind Knee Pain
Know about the knee pain, how the knee works, urgent symptoms, cause of knee pain, diagnosis and treatment options for knee pain.
Written by Dr. Dhankecha Mayank Dineshbhai
Reviewed by Dr. Vasanthasree Nair MBBS
Last updated on 27th Oct, 2025
Introduction
Knee pain is one of the most common joint complaints in everyday life, affecting people of all ages—from teens in sports to adults who sit at desks and older adults with arthritis. Because the knee is a complex hinge joint that bears your body weight and absorbs shock with every step, small issues can quickly become big problems. In this guide, we break down the common reasons behind knee pain and what they feel like, how doctors figure out what’s going on, practical steps you can take at home, and when it’s time to seek medical help. We’ll use clear examples and up-to-date guidance, plus include quick takeaways and FAQs. If symptoms persist beyond two weeks, consult a doctor online with Apollo 24|7 for further evaluation and a personalised plan. Let’s demystify the most common reasons for knee pain so you can move with confidence again.
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How Your Knee Works: A Quick Tour of Anatomy
The knee is a hinge joint that bends and straightens, with a small twist at the end range. Three bones meet here: the femur (thigh), tibia (shin), and patella (kneecap). Articular cartilage covers bone ends so they glide smoothly, and two C-shaped cartilage pads—menisci—act as shock absorbers and help with stability. Think of menisci as rubbery gaskets that distribute load; when they fray or tear, even everyday motions can cause catching, locking, or pain along the joint line.
Four main ligaments stabilise the knee. The ACL and PCL control the front-to-back slide of the tibia, while the MCL and LCL resist side-to-side wobble. Ligaments tend to be injured in sports or slips, especially with rapid deceleration, pivoting, or direct blows. Tendons connect muscle to bone, most notably, the quadriceps tendon above the patella and the patellar tendon below. Overload of the patellar tendon can cause sharp pain when kneeling or jumping.
The patellofemoral joint, where the kneecap tracks in a groove on the femur, is a frequent source of anterior knee pain. If the kneecap tracks slightly off-centre due to weak hip muscles, tight tissues, or altered foot mechanics, you may feel pain when squatting, climbing stairs, or after sitting for a long time (sometimes called “moviegoer’s knee”). Understanding this anatomy helps you map the location of your pain—front, inner, outer, or back—to likely causes, like inner knee pain from a medial meniscus or MCL issue, or swelling behind the knee from a Baker’s cyst.
Red Flags: When Knee Pain Needs Urgent Care
While most knee pain is not an emergency, certain red flags should prompt immediate evaluation. Seek urgent care if you have severe pain with an inability to bear weight after a fall or twisting injury, a visibly deformed knee, or sudden swelling with heat and fever, which can signal infection (septic arthritis). A warm, extremely tender joint with redness, fever, or feeling unwell needs prompt medical attention joint infections can damage cartilage within days.
Other warning signs include calf swelling and tenderness with knee pain, which can suggest a blood clot (DVT)—especially after travel, surgery, or immobilisation. A knee that locks and won’t fully straighten may indicate a displaced meniscus tear (bucket-handle tear). If you heard a pop and your knee gave way with immediate swelling, an ACL tear is possible. People with gout or rheumatoid arthritis who notice a sudden, very painful, swollen joint should also be evaluated to rule out crystal arthritis or a flare.
When to see a doctor within 24–48 hours:
- After an acute injury with persistent swelling or instability.
- Knee pain at night with fever or unexplained weight loss.
- Pain that doesn’t improve with basic care after a week.
- Recurrent swelling behind the knee (possible Baker’s cyst).
If symptoms persist beyond two weeks or you’re unsure about the cause, consult a doctor online with Apollo 24|7 for further evaluation, and book a physical visit if necessary. For suspected infection or gout, blood tests and joint fluid analysis may be needed; Apollo 24|7 offers convenient home collection for labs like CBC, CRP, uric acid, and rheumatoid markers when appropriate.
The Most Common Reasons for Knee Pain (Overview)
Knee pain typically clusters into a few common causes. Recognising patterns can save time and worry.
- Osteoarthritis (OA): Wear-and-tear arthritis increases with age and prior joint injury. Symptoms include stiffness after rest, knee pain at night, arthritis, and pain with prolonged standing or walking. OA affects millions; in the US, arthritis impacts over 58 million adults, with the knee commonly involved [5]. A hallmark is pain that improves a bit with gentle movement and worsens with heavy loads. Swelling is often mild. A Baker’s cyst (swelling behind the knee) can develop as joint fluid tracks into the back of the knee.
- Patellofemoral Pain Syndrome (PFPS): Often called “runner’s knee,” PFPS causes aching around or behind the kneecap, worse when walking downstairs, squatting, or after sitting. It’s common in runners and cyclists and in teens—particularly females—due to alignment and hip strength differences [1][3]. Patellofemoral pain syndrome treatment focuses on hip and thigh strengthening and gradual load management.
- Meniscus Tears: Twisting injuries or gradual wear can tear the meniscus. Symptoms include inner or outer joint line pain and a sensation of catching or locking, sometimes with swelling hours after activity. Meniscus tear vs arthritis symptoms: meniscus pain is often sharp and localised with twist or squat; OA tends to be diffuse and stiff.
- Tendinopathy and Bursitis: Overuse of the patellar tendon (jumpers, heavy squats) causes pain at the front, below the kneecap, especially with jumping or kneeling. Pes anserine bursitis causes inner knee pain, often in middle-aged walkers or those with OA. Prepatellar bursitis can cause swelling directly over the kneecap from frequent kneeling (e.g., gardeners, flooring workers).
- Ligament Sprains/Tears: ACL injuries present with a pop, swelling within hours, and instability. MCL injuries typically cause inner knee pain after a side blow. The difference between ACL and MCL injury: ACL usually results from pivot/landing with instability; MCL often results from valgus stress with localised inner knee tenderness.
- Inflammatory Causes: Gout (uric acid crystals), pseudogout (calcium crystals), and rheumatoid arthritis cause hot, swollen, very painful joints. Gout can be triggered by diet or dehydration; pseudogout is more common with ageing. If suspected, seek care; crystals are confirmed on joint fluid analysis, and targeted medications help.
Alignment and Movement: Why Mechanics Matter
- Knee pain doesn’t happen in isolation—hips, feet, and training loads play a major role. A higher Q-angle (the angle from hip to knee) can predispose to lateral patellar tracking and PFPS. Weak hip abductors and external rotators allow the thigh to drift inward during squats or running, increasing kneecap stress. Flat feet or overpronation may add rotational stress to the knee; a simple shoe and stride audit (video yourself from the front and side) can reveal dynamic knee valgus that aggravates patellofemoral pain.
- Training errors are common reasons for knee pain: suddenly increasing mileage, hills, or plyometrics without giving tendons time to adapt. A useful rule is to increase training load by no more than 10% per week and to separate high-impact days with low-impact cross-training. If you have outer knee pain running, especially on downhills or cambered roads, consider IT band syndrome; shifting to softer surfaces, adjusting cadence to 170–180 steps/min, and avoiding sudden long descents can help.
- Footwear matters, but is not a panacea. Many people benefit from neutral shoes and focusing on cadence and hip strength rather than overcorrecting with stiff motion-control shoes. For sharp knee pain when kneeling, use knee pads and vary tasks to reduce direct pressure on the prepatellar bursa.
How Knee Pain Is Diagnosed
Good diagnosis starts with a conversation. Clinicians ask where the pain is (front, side, back), what activities aggravate it (stairs, sitting, twisting), and whether there was a specific injury. Pain after sitting points to PFPS; catching/locking suggests a meniscal tear; sudden swelling after a pivot injury suggests ACL involvement. Night pain with stiffness can point toward osteoarthritis or inflammatory arthritis.
The physical exam assesses range of motion, swelling, alignment, ligament stability (Lachman, valgus/varus stress), meniscal signs (McMurray, Thessaly), and patellar tracking. Strength of the hips and quadriceps, and foot posture are checked too.
Imaging and tests:
- X-rays: Best for bone and joint space narrowing (OA), fractures, and calcifications (pseudogout). Often, the first imaging is for chronic pain.
- MRI: Best for soft tissues—meniscus, ligaments, cartilage. Reserved for persistent pain or surgical planning.
- Ultrasound: Useful for effusions, cysts, bursitis, and guiding injections.
- Lab tests: Consider CBC, CRP/ESR for infection/inflammation; uric acid for gout; RF/anti-CCP for rheumatoid arthritis. Apollo 24|7 offers home collection for these tests when ordered by your clinician.
Evidence-Based Relief at Home
Most non-emergency knee pain improves with smart self-care. RICE 2.0 means Relative Rest (reduce but don’t completely stop movement), Ice or Heat (ice for swelling or after activity; heat to loosen stiffness), Compression (sleeves can help with proprioception and comfort), and Elevation to reduce swelling. If you need to move quickly on how to reduce knee inflammation fast: compression + elevation + 10–15 minutes of icing after activity, and short-term anti-inflammatory strategies if appropriate.
Activity modifications:
- PFPS: Reduce deep knee flexion (full squats), add step-downs from low height, and emphasise gradual return to stairs and hills.
- Tendinopathy: Shorten lever arms (e.g., partial squats), keep pain ≤3/10 during exercise, and use isometrics (wall sits) to settle pain.
- Meniscus/OA: Avoid deep twist/squat initially, walk on flat surfaces, and try cycling or swimming for cardio.
Best exercises for knee osteoarthritis include quadriceps strengthening (sit-to-stand, mini-squats), hip abductor work (side-lying leg raises, banded walks), and calf raises. Patellofemoral pain often responds to hip + quad strengthening over 6–12 weeks. Topicals (diclofenac gel) can relieve localised pain with fewer systemic effects; acetaminophen or NSAIDs can be considered short-term if you don’t have contraindications. Always follow dosing guidance.
Medical Treatments and Procedures
If home strategies aren’t enough, evidence-based medical care can accelerate recovery. Physical therapy is first-line for PFPS, OA, tendinopathy, and many meniscal issues. Therapists emphasise hip and quadriceps strengthening, patellar taping if indicated, balance work, and load progression. For PFPS, combined hip and knee exercise programs outperform knee-only programs in reducing pain and improving function.
Medications:
Topical NSAIDs (e.g., diclofenac) are effective for OA; oral NSAIDs can help in the short term, but consider risks such as GI upset or cardiovascular effects. For inflammatory flares (gout), medications like colchicine or NSAIDs, and urate-lowering therapy for recurrent episodes, are used after confirmation. In rheumatoid arthritis, early disease-modifying therapy is essential prompt rheumatology referral matters.
Injections:
- Corticosteroid injections can provide short-term relief of inflammatory pain and swelling, especially in OA flares or inflammatory arthritis.
- Hyaluronic acid (viscosupplementation) has mixed evidence; some patients report benefit for mild to moderate OA.
- Platelet-rich plasma (PRP) shows promise in some tendinopathies and mild OA but remains variable in results and coverage.
Surgery: Considered for:
- ACL tears in active individuals with instability.
- Locked meniscus tears or those that fail conservative care.
- Advanced OA after exhaustive nonoperative care—partial or total knee replacement can substantially improve quality of life.
Prevention and Smart Training
Prevention blends strength, skill, and sensible progression. Focus on:
- Strength: Twice-weekly hip and knee work—squats to a comfortable depth, step-ups, bridges, side planks, and calf raises.
- Skill: For runners, increase cadence slightly (5–10%) to reduce joint loading; for cyclists, adjust saddle height to avoid excessive knee flexion.
- Progression: Increase volume or intensity by no more than 10% weekly, deload one week every 4–6 weeks, and vary terrain.
- Equipment: Replace worn shoes every 500–800 km; choose comfort over hype. Knee pads for jobs requiring kneeling help prevent prepatellar bursitis.
- Weight and nutrition: Even a 5–10% weight loss in those with overweight reduces knee load and pain substantially in OA [2]. Ensure adequate protein and vitamin D; Apollo24|7 offers home collection for vitamin D if deficiency is suspected.
Special Cases by Age and Activity
Teens and young athletes: Rapid growth can strain the tibial tubercle (Osgood-Schlatter) or the patellar tendon’s lower pole (Sinding-Larsen-Johansson), causing localised front-of-knee pain with jumping and kneeling. Relative rest, icing after sport, and progressive strengthening usually help. Knee pain in teenagers, growth plate issues typically settle with time.
Runners and cyclists: Runners often face PFPS, IT band syndrome, and tendinopathy; cyclists may experience anterior knee pain if the saddle is too low or cleats are misaligned. For outer knee pain running, add hip abductor strength and check downhill volume. For cyclists, adjust the saddle to allow a slight knee bend at the bottom of the pedal stroke and ensure knees track over the second toe.
Older adults and workers who kneel: OA and bursitis are more common. A combination of strength training, weight management, and appropriate footwear can markedly reduce symptoms. For workers with frequent kneeling, rotate tasks, use cushioned pads, and take brief microbreaks to extend knee health.
Conclusion
Knee pain can be frustrating, but it’s also manageable once you understand the common reasons behind it and how your daily habits influence symptoms. Whether your pain points to patellofemoral stress from stairs, a meniscus issue from twisting, tendinopathy from training spikes, or osteoarthritis from years of hard work, there’s a clear path forward. Start with smart self-care: relative rest, compression, and focused strengthening for hips and quadriceps. Adjust your training load with the 72-hour rule and leverage tools like cadence tweaks or knee pads. A clinician can confirm the diagnosis, tailor exercises, and discuss options like medications, injections, or, in select cases, surgery. Your goal isn’t just to reduce pain but to restore confidence in movement. If your condition does not improve after trying these methods, book a physical visit to a doctor with Apollo24|7 or consult online for expert guidance. With the right plan, most people get back to the activities they love stronger and smarter than before.
Consult a Top Rheumatologist for Personalised Advice
Consult a Top Rheumatologist for Personalised Advice
Dr. Anand Ravi
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Thorana Prakash M
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Ramineni Naga Tejaswini
Rheumatologist
3 Years • MBBS, DNB(Internal Medicine), DrNB ( Clinical Immunology and Rheumatology)
Hyderabad
Apollo Hospitals Jubilee Hills Hyderabad, Hyderabad
Dr. Ramesh Ramamoorthy
Rheumatologist
20 Years • MD (Internal Medicine), DM (Rheumatology)
Chennai
Apollo Hospitals Greams Road, Chennai
(25+ Patients)
Dr Aishwarya G
Rheumatologist
10 Years • MBBS,. MD (General Medicine), DM (Clinical Immunology and Rheumatology)
Chennai
Apollo Speciality Hospitals OMR, Chennai
(50+ Patients)
Consult a Top Rheumatologist for Personalised Advice
Dr. Anand Ravi
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Thorana Prakash M
General Physician
2 Years • MBBS
Bengaluru
PRESTIGE SHANTHINIKETAN - SOCIETY CLINIC, Bengaluru
Dr. Ramineni Naga Tejaswini
Rheumatologist
3 Years • MBBS, DNB(Internal Medicine), DrNB ( Clinical Immunology and Rheumatology)
Hyderabad
Apollo Hospitals Jubilee Hills Hyderabad, Hyderabad
Dr. Ramesh Ramamoorthy
Rheumatologist
20 Years • MD (Internal Medicine), DM (Rheumatology)
Chennai
Apollo Hospitals Greams Road, Chennai
(25+ Patients)
Dr Aishwarya G
Rheumatologist
10 Years • MBBS,. MD (General Medicine), DM (Clinical Immunology and Rheumatology)
Chennai
Apollo Speciality Hospitals OMR, Chennai
(50+ Patients)
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Frequently Asked Questions
What are the most common causes of knee pain when walking downstairs?
Descending stairs increases kneecap compression, so patellofemoral pain syndrome is most common. Quadriceps weakness and hip mechanics contribute; targeted strengthening and load management usually help.
How do I tell the difference between an ACL and an MCL injury?
ACL injuries often involve a pop, swelling within hours, and instability after a pivot or landing. MCL injuries follow a side blow with inner knee tenderness but less instability. Seek evaluation for accurate diagnosis and rehab planning.
What’s the best initial treatment for inner knee pain?
Inner knee pain causes include medial meniscus issues, MCL sprain, and pes anserine bursitis. Start with RICE 2.0, gentle range-of-motion, and short walks. If pain persists beyond two weeks, consult a doctor online with Apollo24|7 for further evaluation.
Should I get an MRI right away for knee pain?
Not usually. X-rays are often first for chronic pain to assess osteoarthritis, while MRI is reserved for suspected meniscal or ligament tears or when conservative care fails. Your clinician will decide based on the exam and symptoms.
What helps knee pain after sitting (moviegoer’s knee)?
Likely patellofemoral pain. Stand and move every 30–45 minutes, strengthen hips/quads, and gradually reintroduce stairs. Topical NSAIDs and compression sleeves can provide symptom relief.