Knee Pain 101: Common Causes and When to Seek Help

Knee pain can creep up on you, whether it’s a dull ache after a long day or a sharp pain that stops you in your tracks. You’re not alone. Knee pain affects 1 in 4 adults and is one of the most common reasons people visit orthopaedic specialists.

But how do you know if it’s something that will go away with rest, or if it needs medical attention? This guide will break down the most common causes of knee pain and when to seek help.

Common Causes of Knee Pain

1. Sports Injuries (Ligament & Meniscus Tears)

If you’ve ever felt your knee "pop" during a sudden movement, you might have a ligament injury. These injuries are common in athletes, especially those in sports like soccer, netball, and skiing.

• ACL Tears – The anterior cruciate ligament (ACL) helps stabilise the knee. When torn, the knee often swells quickly and feels unstable. Surgery is often required for active individuals.

• Meniscus Tears – Your meniscus is a cushion between the bones of your knee. A sudden twist or deep squat can tear it, leading to pain, swelling, and stiffness.

  
  

SORI’s research: Our studies on ACL rehabilitation show that objective testing, like motion capture and force plate analysis, can help predict a successful return to sport.

2. Arthritis (Wear and Tear Over Time)

Not all knee pain comes from an injury. Sometimes, it sneaks up over the years as cartilage wears down, causing stiffness and discomfort.

• Osteoarthritis – The most common form, often called "wear-and-tear arthritis." Cartilage wears away, leading to pain, swelling, and stiffness that worsens over time.

• Rheumatoid Arthritis – An autoimmune disease that causes inflammation in the knee joint, leading to pain even when you’re at rest.

SORI’s research: We study surgical options like high tibial osteotomy (HTO) to delay or prevent knee replacements in younger patients with osteoarthritis. (Read about knee realignment)

3. Overuse Injuries (Pain from Everyday Life & Exercise)

Sometimes, knee pain isn’t from one big moment, it builds up over time.

• Runner’s Knee (Patellofemoral Pain Syndrome) – Pain at the front of the knee from repetitive stress, especially with running, squatting, or stairs.

• Tendinitis (Jumper’s Knee) – Inflammation of the patellar tendon, often seen in basketball and volleyball players.

• Bursitis – Swelling of fluid-filled sacs around the knee, often caused by kneeling for long periods.

  
  

SORI’s research: We use motion analysis to evaluate these overuse injuries and optimise rehabilitation programs.

When Should You See a Doctor?

Sometimes, knee pain goes away with rest, but in other cases, it shouldn’t be ignored. Seek medical attention if you experience:

• Sudden swelling or intense pain after an injury

• Your knee gives out or feels unstable when you walk

• A deep, aching pain that lasts more than a few weeks

• Locking, clicking, or trouble straightening your knee

Final Thoughts

Your knees work hard every day, and they deserve attention when pain strikes. Whether it’s an old injury flaring up or a sign of arthritis, there are solutions.

At Sydney Orthopaedic Research Institute (SORI), we specialise in understanding knee pain at every stage, from injury prevention to recovery and surgery. If you want to learn more about cutting-edge knee research, check out our latest publications.