Patellofemoral syndrome
Background
- Also known as "Runner's Knee"
- Major cause of anterior knee pain (especially in women)
- Pain comes from contact of posterior surface of patella with the femur
- Term Chondromalacia patella typically used synonymously, however this term implies softening of the cartilage
Major Causes
- Focal trauma (least common)
- Overuse
- Abnormal patellar tracking (due to quadriceps weakness)
Clinical Features
- Gradual onset of unilateral, anterior knee pain, nonradiating
- Pain worsened by prolonged knee flexion ("moviegoer syndrome") and stair climbing
Patellar grind test
- Press patella away from femoral condyles while patient contracts the quadriceps
- Sudden patellar pain and relaxation of the muscle is positive test
Differential Diagnosis
Knee diagnoses
Acute knee injury
- Knee dislocation
- Knee fractures
- Meniscus and ligament knee injuries
- Patella dislocation
- Patellar tendonitis
- Patellar tendon rupture
- Quadriceps tendon rupture
Nontraumatic/Subacute
- Arthritis
- Gout and Pseudogout
- Osgood-Schlatter disease
- Patellofemoral syndrome (Runner's Knee)
- Patellar tendonitis (Jumper's knee)
- Pes anserine bursitis
- Popliteal cyst (Bakers cyst)
- Prepatellar bursitis (nonseptic)
- Septic bursitis
- Septic joint
- DVT
Evaluation
- Knee XR series
- Patella may not line up with groove of the femur on sunrise view
- Decreased space posterior to patella
- Bony erosions
Management
- Conservative therapy (with emphasis on physical therapy and strengthening)
Disposition
- Outpatient management