Knee pain is one of the most common musculoskeletal complaints people experience, regardless of age or activity level. For some, it starts suddenly after a sports injury. For others, it develops gradually, making everyday activities like climbing stairs or walking uncomfortable. Because the knee is a complex joint that bears much of the body’s weight, pain in this area can have a wide range of underlying causes.
This article touches on the most frequent reasons behind knee pain, how these conditions typically present, and why seeking timely medical assessment from an orthopaedic specialist can make a major difference in treatment outcomes.
What Does the Knee Comprise Of?
The knee is made up of three main bones: the thighbone (femur), the shinbone (tibia), and the kneecap (patella). These bones are supported by a network of ligaments, tendons, cartilage, and muscles that work together to allow movement, stability and shock absorption. When any of these structures are injured, irritated, or worn down, pain can occur.
Common Causes of Knee Pain
1. Ligament Injuries
The knee has four primary ligaments that provide stability: the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL).
- ACL injuries often happen during sports that involve sudden stops, pivots, or changes in direction. A “pop” sound at the time of injury is common, followed by swelling and instability.
- MCL and LCL injuries are usually caused by direct blows to the knee or awkward landings. Pain is often felt along the inner or outer side of the knee.
- PCL injuries are less common and usually occur from trauma, such as a fall on a bent knee or a car accident.
Ligament injuries can range from mild sprains to complete tears, and treatment options vary depending on severity.
2. Meniscus Tears
The menisci are two C-shaped pieces of cartilage that cushion and stabilize the knee joint. They act as shock absorbers between the femur and tibia.
A meniscus tear can occur from twisting or rotating the knee while bearing weight, often during sports or even from something as simple as standing up awkwardly. Symptoms may include pain, swelling, stiffness, and a sensation of the knee “locking” or “catching.”
In younger patients, meniscus tears often result from trauma, while in older adults, they can happen due to gradual degeneration of the cartilage.
3. Tendinitis and Tendinopathy
Tendons are the connective tissues that attach muscles to bones. Overuse, repetitive strain, or sudden increases in activity can irritate the tendons around the knee.
- Patellar tendinitis (sometimes called “jumper’s knee”) affects the tendon connecting the kneecap to the shinbone. It’s common in athletes who play basketball, volleyball, or other jumping sports.
- Quadriceps tendinitis involves the tendon that attaches the thigh muscles to the kneecap.
Symptoms typically include localized pain that worsens with activity, particularly when jumping, running, or climbing stairs. Chronic overuse may lead to tendinopathy, where the tendon undergoes structural changes and becomes harder to heal.
4. Osteoarthritis
One of the most frequent causes of chronic knee pain, osteoarthritis is a degenerative joint disease where the protective cartilage wears away over time. Without this cushioning, bones rub against each other, causing pain, swelling, stiffness and reduced mobility.
Osteoarthritis of the knee tends to develop gradually and is more common with age, though it can also affect younger people after injury or repetitive joint stress. Patients often notice morning stiffness or pain that worsens after activity.
5. Rheumatoid Arthritis and Other Inflammatory Conditions
While osteoarthritis results from wear-and-tear, rheumatoid arthritis is an autoimmune condition where the body’s immune system attacks the joints. This can lead to inflammation, pain, swelling, and joint deformity if untreated.
Other inflammatory conditions such as gout, psoriatic arthritis, or lupus can also affect the knee, leading to episodes of intense pain and swelling.
6. Bursitis
Bursae are small fluid-filled sacs that cushion the knee joint. When they become inflamed due to repeated pressure, overuse, or direct trauma, the result is bursitis.
Prepatellar bursitis, sometimes known as “housemaid’s knee,” often develops from prolonged kneeling. Symptoms include swelling in front of the kneecap and tenderness, which may make it difficult to bend the knee.
7. Iliotibial Band Syndrome (ITBS)
The iliotibial band is a thick band of tissue that runs along the outside of the thigh, from the hip to the knee. When this band becomes tight or irritated, it can rub against the outer part of the knee joint, leading to pain on the outside of the knee.
ITBS is common in long-distance runners, cyclists, and people who suddenly increase their exercise intensity without proper conditioning.
8. Patellofemoral Pain Syndrome
Sometimes referred to as “runner’s knee,” patellofemoral pain syndrome describes pain at the front of the knee and around the kneecap. It often worsens with activities like squatting, climbing stairs, or sitting for long periods with bent knees.
This condition is linked to muscle imbalances, overuse, or improper alignment of the kneecap. Although it is especially common in younger athletes, it can affect anyone.
9. Fractures
Fractures of the kneecap (patella), femur, or tibia around the knee joint usually result from high-impact trauma such as a fall, car accident, or severe sports injury. These are often very painful, associated with swelling and an inability to bear weight. Fractures require immediate medical attention.
10. Other Causes
In addition to the above, knee pain can also result from less common conditions such as cysts (like Baker’s cyst), referred pain from hip or back problems, or infections that require urgent treatment.
When Should You See a Doctor for Knee Pain?
While mild aches may improve with rest, ice and over-the-counter pain relief, some symptoms warrant consultation with an orthopaedic specialist:
- Sudden, severe knee pain after an injury
- Swelling that does not improve within a few days
- A feeling that the knee is unstable or “giving way”
- Inability to bear weight or straighten the knee
- Redness, warmth, or fever accompanying knee pain
- Chronic pain that interferes with daily activities
Early evaluation helps prevent conditions from worsening and allows timely treatment, which may include physiotherapy, medication, injections, or surgery depending on the cause.
How an Orthopaedic Specialist Can Help
An orthopaedic surgeon uses a combination of patient history, physical examination, and imaging studies such as X-rays or MRI scans to determine the underlying cause of knee pain. From there, a tailored treatment plan can be developed.
Treatment may involve:
- Conservative measures such as rest, physiotherapy, and activity modification.
- Medications including anti-inflammatory drugs or injections to reduce pain and swelling.
- Minimally invasive procedures such as arthroscopy to repair or remove damaged tissue.
- Surgical options like ligament reconstruction or joint replacement for severe or advanced cases.
If you are experiencing ongoing knee pain, consulting an orthopaedic specialist can provide clarity and a path to recovery, helping you regain comfort and mobility in your day-to-day life.
