Causes of knee pain
Introduction
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
Trauma
- Fracture of femur, tibia, fibula, patella
- Ligamentous sprain (ACL, MCL, LCL, PCL)
- Meniscal tear
- Muscle strain
- Osteochodral fracture
- Patellar subluxation/dislocation
Atraumatic
- 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