Pain in the Knee: Causes, Treatments, and When to Seek Help
Pain in the knee is one of the most common complaints that brings people to a clinic. It affects people of all ages — from teenagers with growing pains to older adults dealing with years of cartilage wear. It can arrive suddenly after an awkward twist, or creep up gradually without any obvious cause.
Whatever your situation, one thing is consistent: knee pain that does not settle on its own deserves proper attention. Carrying on regardless rarely makes it better. Understanding what is behind the pain is the first step towards doing something about it.
This guide covers the main causes of pain in the knee, how to recognise the symptoms, what you can do at home, and when a more targeted treatment — including an Arthrosamid injection — may be the right next step.
What Causes Pain in the Knee?
The knee is a complex joint. It relies on cartilage, ligaments, tendons, fluid-filled sacs called bursae, and the surrounding muscles all working together. When any of those structures become damaged, inflamed, or worn, you feel it as pain.
The most common causes fall into two broad categories: pain from an injury, and pain without any obvious injury.
Knee Pain From an Injury
Injuries often produce sudden, sharp pain with an identifiable cause — a fall, a twist, a collision, or an awkward landing.
Sprains and strains are the most frequent. The ligaments that hold the knee together get overstretched, causing pain, swelling, and instability. Mild sprains settle with rest; significant ones may involve partial or complete tears that need clinical assessment.
Torn meniscus is common in people who twist the knee suddenly while bearing weight on it — a frequent sports injury but also something that can happen stepping off a kerb unexpectedly. Pain on the inner or outer side of the knee, a catching or locking sensation, and swelling that appears within hours are all classic signs.
ACL injury — a tear of the anterior cruciate ligament — typically causes a popping sensation at the time of injury, followed by rapid swelling and the knee feeling unstable. It is common in sports involving sudden direction changes.
Patellar tendinitis develops through repetitive loading of the tendon just below the kneecap. Runners, cyclists, and anyone who climbs a lot of stairs can develop this. Pain tends to be felt at the front of the knee, just below the kneecap.
Bursitis occurs when the small fluid-filled sacs that cushion the knee become inflamed — often from prolonged kneeling or direct impact. The knee looks swollen and feels warm and tender to touch.
Knee Pain Without an Obvious Injury
This is where many people find themselves confused. The knee starts hurting — but nothing happened. No fall, no sport, no incident. It just started.
This is actually more common than injury-related knee pain, particularly in people over 40. The cause is usually a gradual process rather than a sudden event.
Knee osteoarthritis is by far the most common cause of non-injury knee pain, especially in people over 50. It develops when the cartilage that cushions the ends of the bones inside the knee gradually wears away. As the cartilage thins, the bones come closer together. The joint becomes inflamed, stiff, and painful.
Osteoarthritis does not always start dramatically. Many people notice it as morning stiffness that eases after a few minutes of movement. Then comes pain that gets worse with activity — particularly stairs, hills, or getting up from a low chair. Over time, the pain creeps into rest as well.
Gout causes sudden, severe attacks of pain — often with redness and heat — when uric acid crystals build up inside the joint. It can feel almost indistinguishable from an infection in the knee, and requires specific diagnosis and treatment.
Rheumatoid arthritis is an autoimmune condition where the body attacks its own joint lining. It affects women more than men and tends to cause pain and swelling in multiple joints simultaneously. It requires specialist management.Iliotibial band syndrome produces pain on the outer side of the knee. It is particularly common in people who walk long distances and is caused by the iliotibial band — a thick strip of connective tissue running from the hip to the knee — becoming tight and irritated.
Recognising the Symptoms of Knee Pain
Where the pain sits in the knee, and what makes it better or worse, often tells a clinician a great deal about the underlying cause.
Here is a practical guide to common symptom patterns:
Pain at the front of the knee — around or behind the kneecap — often points to patellofemoral pain syndrome or patellar tendinitis. It tends to worsen going downstairs or after prolonged sitting.
Pain on the inner side of the knee — frequently associated with medial meniscus problems or medial ligament strain. Common after twisting injuries.
Pain on the outer side of the knee — often IT band syndrome or lateral meniscus damage. Typically worsens during or after sustained walking.
Diffuse pain throughout the knee, worse in the morning, with stiffness — the classic picture of osteoarthritis.
Sudden severe pain with redness and heat — consider gout, bursitis, or joint infection. Seek prompt medical attention.
Swelling that appears within hours of an injury — suggests bleeding inside the joint. See a doctor promptly.
Pain that locks the knee or causes it to give way — may indicate meniscal damage or ligament instability. Requires clinical assessment.
What You Can Do at Home for Knee Pain
For mild to moderate knee pain — particularly after a minor injury or a flare-up of a known condition — initial self-care at home is often effective.
Rest the knee. Reduce the activities that aggravate it. You do not need to stay completely still, but avoid anything that makes the pain significantly worse. Gentle movement is better than complete immobilisation.
Apply ice. Wrap ice or a bag of frozen peas in a damp cloth and apply to the knee for 15 to 20 minutes every two to three hours for the first 48 to 72 hours. Never put ice directly onto the skin — it causes burns.
Use pain relief. Paracetamol is the first-line recommendation from NICE for musculoskeletal pain. It is effective, well-tolerated, and suitable for most adults when taken as directed. Topical anti-inflammatories such as diclofenac gel applied directly to the knee often work well for localised inflammation without the risks of oral anti-inflammatory tablets. If you need oral NSAIDs such as ibuprofen, use the lowest effective dose for the shortest time, and check with your GP if you take other medication or have stomach, kidney, or heart conditions.
Elevate the leg when resting. This helps reduce swelling by encouraging fluid to drain away from the joint.
Keep moving gently. Once the initial acute phase settles, gentle movement — short walks, simple range-of-motion exercises — helps the knee recover faster than rest alone. Every hour or so, bend and straighten the knee slowly for 10 to 20 seconds. Stiffness gets worse the longer you stay still.
Modify aggravating activities. If kneeling hurts, use knee pads. If prolonged sitting causes stiffness, get up every 30 minutes. If stairs are painful, lead with your stronger leg going up and your weaker leg coming down.
When to See a Doctor
Most knee pain settles within a few days to a week with the measures above. See a GP if your pain does not improve after one to two weeks of self-care, or sooner if any of the following apply:
- The knee is significantly swollen and you are struggling to bear weight
- The pain is severe and came on suddenly
- The knee locks, gives way, or feels unstable
- There is warmth, redness, and fever — which can indicate a joint infection (seek help urgently)
- You heard or felt a popping or snapping sensation at the time of injury
- The pain is coming on at night and waking you from sleep
Your GP can examine the knee, arrange an X-ray or MRI if needed, and refer you to a physiotherapist or orthopaedic specialist depending on what they find.
Treatment Options for Knee Pain
The right treatment depends entirely on the cause. Here is an honest overview.
Physiotherapy
Physiotherapy is the cornerstone of treatment for most causes of knee pain. A good physiotherapist identifies not just the pain but the reason behind it — muscle weakness, poor movement patterns, biomechanical issues — and builds a programme to address those root causes. Strengthening the quadriceps, hamstrings, and hip stabilisers reduces the load on the knee joint and can produce meaningful, lasting improvement.
Do not underestimate physiotherapy. Many people dismiss it as “just exercises” — but consistently followed, targeted rehabilitation resolves knee pain that has persisted for months.
Steroid Injections
A corticosteroid injection into the knee reduces inflammation and can provide significant pain relief — typically within a few days. For acute flare-ups of osteoarthritis or bursitis, a steroid injection can be genuinely helpful.
The limitation is duration. Relief typically lasts weeks to a few months. Repeated steroid injections can damage cartilage and the surrounding tissue over time, which makes them a poor long-term strategy.
Hyaluronic Acid Injections
These injections supplement the natural lubricating fluid inside the knee. NICE no longer recommends hyaluronic acid injections for knee osteoarthritis management, as the evidence for sustained benefit is considered insufficient. Some patients report short-term benefit, but they are not considered a reliable long-term option.
When Conservative Treatment Is Not Enough — Is an Arthrosamid Injection the Answer?
For many people with pain in the knee, conservative treatment eventually reaches its limit. Physiotherapy helps, but the pain keeps coming back. Steroid injections provide shorter and shorter windows of relief. Activity stays restricted. Quality of life suffers.
This is where an Arthrosamid injection becomes worth exploring — particularly for patients with mild to moderate knee osteoarthritis.
What Is an Arthrosamid Injection?
An Arthrosamid injection delivers a non-biodegradable hydrogel — composed of 97.5% water and 2.5% cross-linked polyacrylamide — directly into the knee joint under ultrasound guidance. Once inside the joint, the hydrogel integrates with the synovial membrane, the soft lining of the knee, over a period of four to six weeks.
This integration may help to reduce inflammation, restore some of the joint’s natural cushioning, and improve its elasticity — effects that standard pain relief and steroid injections simply cannot provide.
It is a single injection. Not a course. Not something you need to repeat every few months.
How Long Do the Results Last?
Published clinical studies report sustained improvements in pain and function for up to five years following a single Arthrosamid injection in suitable patients. A 2025 five-year follow-up study confirmed continued meaningful improvements at that point. For someone who has been managing persistent knee pain for years, relief that lasts potentially five years from one minimally invasive procedure is a significant shift from what steroid injections or pain relief tablets can offer.
How Is Arthrosamid Different From a Steroid Injection?
A steroid injection reduces inflammation temporarily and has no lasting effect on the joint’s structure. Repeated use carries genuine risks of cartilage damage.
An Arthrosamid injection works physically — it integrates with the joint tissue and provides lasting structural support. There are no drugs involved. There is no degradation over time because the hydrogel is non-biodegradable. The relief builds gradually rather than arriving overnight, but it lasts far longer.
Who Is Suitable for an Arthrosamid Injection?
Arthrosamid tends to be most appropriate for patients who:
- Have mild to moderate knee osteoarthritis confirmed on imaging
- Have already tried physiotherapy, weight management, and pain relief without sufficient benefit
- Continue to experience meaningful pain that limits daily activity
- Are not ready for — or wish to avoid or delay — knee replacement surgery
It is not suitable for everyone. Patients with very advanced bone-on-bone arthritis, active joint infection, or allergy to polyacrylamide are generally not good candidates. The only way to confirm suitability is a proper clinical assessment with an experienced orthopaedic clinician.
What Is the Procedure Like?
The full appointment takes 30 to 45 minutes. Local anaesthetic is applied to the knee before the injection. Most patients describe the sensation as mild pressure. The injection is delivered under ultrasound guidance to ensure precise placement inside the joint.
You go home the same day. Most patients return to light daily activity within one to two days. The main improvement in pain and stiffness typically becomes noticeable between weeks eight and twelve as the hydrogel fully integrates.
Preventing Knee Pain From Getting Worse
Whether your knee pain is mild or significant, there are practical steps you can take to protect the joint and slow any underlying deterioration.
Maintain a healthy weight. Every kilogram of excess body weight adds roughly three to four kilograms of force across the knee joint with each step. Even modest weight loss significantly reduces the load on an already-stressed joint.
Keep the supporting muscles strong. The quadriceps at the front of the thigh are the knee’s primary protectors. Weak quadriceps means the joint itself absorbs more force. Exercises like supported squats, straight-leg raises, and step-ups — guided by a physiotherapist — make a measurable difference.
Choose low-impact activity when the knee is flaring. Swimming, cycling, and walking in water are excellent for maintaining fitness and strength without adding stress to the knee.
Wear appropriate footwear. Shoes with adequate cushioning and support reduce impact through the knee on hard surfaces.
Do not ignore persistent pain. Pain is a signal. Carrying on through significant knee pain without addressing the cause accelerates the damage — and makes future treatment more difficult.
Key Takeaways
- Pain in the knee has many possible causes — correct diagnosis matters before any treatment begins
- Most mild knee pain responds to rest, ice, paracetamol, and gentle movement
- Persistent or worsening pain, swelling, instability, or locking requires proper clinical assessment
- For knee osteoarthritis that has not responded to conservative treatment, an Arthrosamid injection offers a minimally invasive option with evidence of sustained relief for up to five years from a single procedure
- Getting the right diagnosis is the essential first step. From there, the right treatment is rarely one-size-fits-all.
If you are experiencing persistent pain in the knee and want an honest clinical assessment of your options, Mr S N Abbas offers private knee consultations at 48 Wimpole Street, Marylebone, London. The initial consultation costs £100, fully redeemable against treatment cost if you proceed. Book online or call the clinic directly.
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