Causes of knee pain


There are surprisingly large number of causes of pain in the knee. The good thing about the knee is that it is made of 3 distinct compartments- the medial (inside) and lateral (outside) and patello-femoral (front or anterior) compartment. Also because the knee is just under the skin, it becomes very easy to diagnose the cause of the pain. By looking at the age , location and mechanism of injury therefore one can make a very reasonable diagnosis of the cause of the pain.

Causes of pain by age

Children and adolescents

- Jumper’s knee (patellar tendonitis)

- Juvenile rheumatoid arthritis

- Osteochondritis dissecans

- Patellar subluxation

- Referred pain: slipped capital femoral epiphysis, hip fracture

- Tibial apophysitis (Osgood-Schlatter lesion)

- Trauma: ligamentous sprains (anterior cruciate, medial collateral, lateral collateral), meniscal tear, fractures including epiphyseal fracture , muscle strains

Young adults

- Inflammatory arthropathy: rheumatoid arthritis, Reiter’s syndrome, Pigmented villonodular Synovitis

- Medial plica syndrome

- Patellofemoral pain syndrome (chondromalacia patellae)

- Pes anserine bursitis

- Septic arthritis

- Stress fracture/Stress reaction

- Tendonitis (quadriceps, Patellar tendon, etc)

- Trauma: ligamentous sprains (anterior cruciate, medial collateral, lateral collateral), meniscal tear, fractures, muscle strains

- Referred Pain: neurogenic, hip and leg pathology

Older adults

- Crystal-induced inflammatory arthropathy: gout, pseudogout

- Osteoarthritis

- Popliteal cyst (Baker’s cyst)

- Metastatic cancer

Common Knee pain by Anatomic Site (Figure 1)

Anterior knee pain

- Jumper's knee (patellar tendonitis)1

- Patellar subluxation or dislocation2

- Patellofemoral pain syndrome (chondromalacia patellae)3

- Tibial apophysitis (Osgood-Schlatter lesion)4

Medial knee pain

- Medial collateral ligament sprain5

- Medial meniscal tear6

- Medial plica syndrome7

- Pes anserine bursitis8

Lateral knee pain

- Iliotibial-band tendonitis9

- Lateral collateral ligament sprain10

- Lateral meniscal tear11

Posterior knee pain

- Popliteal cyst (Baker's cyst)12

- Posterior cruciate ligament injury13

Figure 1. Sites of pain of typical conditions of the knee. Numbers refer to superscript numbers under anatomical site.

Mechanism of Injury


- Fracture of femur, tibia, fibula, patella

- Ligamentous sprain (ACL, MCL, LCL, PCL)

- Meniscal tear

- Muscle strain

- Osteochodral fracture

- Patellar subluxation/dislocation


- Medial plica syndrome

- Osteoarthrits

- Patellofemoral Syndrome

- Popliteal cyst

- Rheumatoid or other inflammatory arthritis (pigmented villonodular arthritis, gout, Reiter's syndrome)

- Septic arthrits

- Stress fractures/reactions (tibial plateau & shaft, femur, patella)

- Tendonitis

- Referred pain (hip osteoarthritis, lumbar radicular symptoms)

- Metastatic cancer