Knee pain

Medically reviewed by Dr. K. G. Gopalakrishna, Consultant Orthopaedic Surgeon · Last reviewed: August 2026

The knee is the largest joint in the body and carries your full weight with every step, which is exactly why it's one of the most common reasons people see an orthopaedic surgeon. The good news: most knee pain is manageable without surgery, and understanding what's actually happening in the joint is the first step to treating it correctly rather than guessing.

What's actually there

The knee joins the thigh bone (femur) to the shin bone (tibia), with the kneecap (patella) sitting in front. Between the femur and tibia sit two C-shaped cushions called the menisci, which absorb shock. Four main ligaments - including the ACL and PCL - hold the joint stable during twisting and pivoting movements. Pain can come from any of these structures individually, or from the smooth cartilage that lines the joint wearing down over time.

Common causes

• Wear-related: Osteoarthritis - the cartilage lining the joint gradually thins, usually from years of use, more common after 45 and often worse in people who are overweight or have had a previous knee injury.
• Injury-related: A sudden twist, especially during sport, can tear the ACL or meniscus. A direct blow or fall can bruise or fracture the joint. Overuse injuries like patellar tendinitis ("jumper's knee") come from repetitive strain rather than a single incident.
• Inflammatory: Conditions like rheumatoid arthritis or gout can affect the knee specifically, often with visible swelling and warmth.
• Referred pain: Occasionally, pain felt in the knee actually originates in the hip - the two joints share nerve pathways, so hip arthritis can masquerade as knee pain.
• Gym and training-related: Squats, lunges, and heavy leg press can strain or injure the knee, particularly with poor knee tracking or a sudden increase in weight before the joint and surrounding muscles are ready for it.

What it tends to feel like

Wear-related pain is usually a dull ache that worsens with activity and improves with rest, often stiff after sitting still for a while. A ligament or meniscus tear tends to come with a specific incident you can point to, sometimes a popping sensation, followed by swelling within hours. Pain that's sharp with certain movements (like going down stairs) often points to the kneecap or meniscus specifically.

When to seek care urgently

• The knee is visibly deformed after an injury
• You cannot bear any weight on it at all
• It locks and will not straighten
• It's hot, red, and rapidly swelling (can indicate infection or gout - should not wait)

What's usually tried first

• Relative rest and activity modification - not necessarily complete rest, but reducing the movements that provoke pain
• Physiotherapy focused on strengthening the muscles that support the joint, particularly the quadriceps
• Weight management, since every extra kilogram translates to several times that in extra load through the knee with each step
• Anti-inflammatory medication for short-term flare-ups
• A knee brace or support for activity-related instability
• For early-to-moderate arthritis, joint injections (including PRP) can meaningfully reduce pain and delay the need for anything further

Myths vs facts

• Myth: Cracking your knees causes arthritis.
  Fact: The sound is usually just gas bubbles releasing in the joint fluid - no evidence links it to arthritis.
• Myth: You should avoid all exercise if your knee hurts.
  Fact: Complete rest often makes wear-related knee pain worse. The right kind of movement - low-impact, guided by a physiotherapist - usually helps more than stopping entirely.

When surgery enters the conversation

If imaging confirms a torn ligament or meniscus that isn't improving with rehabilitation - particularly in an active or younger patient - keyhole arthroscopy can repair or clean up the damage with a short recovery. Total knee replacement is considered only when arthritis has progressed to bone-on-bone contact, pain persists even at rest or disturbs sleep, and walking or stairs are significantly limited despite exhausting the options above. It's a considered, later-stage decision, not a first response to knee pain.

Recovery, broadly:

• Arthroscopy - most people are walking comfortably within days and back to normal activity within 4-6 weeks.
• Total knee replacement, week 1: walking short distances with a walker or frame, pain managed with medication.
• Weeks 2-6: progressing to a stick, physiotherapy focused on regaining bend and straightening the knee fully.
• Months 2-6: building strength and confidence in the joint, most people resuming normal daily activities and gentle exercise.

Looking after your knee

• Maintain a healthy weight - this is the single biggest modifiable factor in knee joint load
• Keep the muscles around the knee (especially quadriceps) strong, even without existing pain
• Warm up before sport and avoid sudden increases in training intensity
• Choose supportive footwear, particularly for running or repetitive impact activity
• Keep knees tracking in line with the toes during squats and lunges, and increase weight gradually rather than jumping levels too quickly
• Don't ignore a "minor" twist during sport - early assessment of a suspected ligament injury leads to better outcomes than waiting

FAQs: questions worth asking your doctor