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Patellofemoral SyndromeAka: Chondromalacia Patellae, Patellofemoral Pain Syndrome, Miserable Malalignment Syndrome, Runner's Knee, PFPS

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  1. Epidemiology
    1. Most common Running Injury
  2. Causes of patellofemoral or anterior Knee Pain
    1. Soft tissue causes
      1. Prepatellar Bursitis
      2. Patella Tendonitis
      3. Meniscus Tear
    2. Articular causes
      1. Chondromalacia patellae
      2. Patella Osteoarthritis
      3. Osteochondritis Dissecans of the Knee
      4. Chondral Fracture
    3. Functional causes
      1. Patella instability
      2. Synovial plica
        1. Synovium caught between patella and femur
    4. Referred pain
      1. Back pain
      2. Hip Pain
      3. Ankle pain
  3. Mechanism
    1. Overuse syndrome in athletes
      1. Sports involving Running, jumping or cutting
      2. Cyclist or runner going too far, too soon, too fast
      3. Basketball and Volleyball with repetitive jumping
      4. Frequent change of playing surface (grass to wood)
      5. Repetitive squats or lunges
      6. Excessively worn shoes
      7. Contact sports (Football or Rugby)
        1. Direct impact to patella
    2. Degeneration of patella
      1. Chondromalacia patellae
      2. Osteoarthritis of the knee
    3. Patella mal-tracking in the patellofemoral groove
      1. Asymmetric quadriceps muscle strength
      2. Vastus medialis is often weaker than other muscle
      3. Patella is often pulled to the outside (J-tracking)
      4. Results in local wearing of the articular cartilage
    4. Anatomic variation: Increased Q-Angle
      1. Increased angle between femur and tibia (Q-Angle)
        1. Women more often have larger Q-angle
      2. On Quadriceps contraction, patella is pushed outward
      3. Leads to mal-tracking of the patella as above
    5. Anatomic variation: Shallow outer patellofemoral groove
      1. Patella prone to sublux or dislocate laterally
  4. Symptoms
    1. Anterior Knee Pain
    2. Pain beneath, under or peri-patellar
    3. Stiffness
    4. Gradually progressive general aching or grating pain
    5. Provocative factors
      1. Going up or down stairs, or down hills
      2. Running
      3. Squatting
      4. Prolonged sitting with knee bent (Theater sign)
    6. Giving-way sensation (reflex response to pain)
    7. Grinding, popping, or clicking sound on knee flexion
    8. No locking or catching (suggests Meniscal Injury)
  5. Signs
    1. Inspection
      1. Excessive pronation on Running gait
      2. No Knee Effusion
      3. Abnormal patella alignment and tracking
        1. See Patella Tracking Assessment (J Sign)
        2. Increased Q Angle of the Knee
      4. Lateral knee structures tight
        1. Patella Glide Test
        2. Patella tilt test
    2. Palpation
      1. Tender undersurface of medial or lateral patella
      2. Crepitation on knee range of motion
    3. Provocative testing
      1. Positive Patellar Apprehension Test
  6. Radiology: Knee XRay
    1. Uncommonly of clinical use in patellofemoral syndrome
    2. Indications
      1. Age >50 years
        1. Patellofemoral Osteoarthritis
      2. Child and Adolescent
        1. Osteochondritis dissecans
        2. Bone neoplasms
    3. Views
      1. Weight-bearing AP Xray
      2. Weight-bearing lateral Xray
      3. Sunrise (Axial view at 20-45 degrees)
  7. Management: Medical
    1. Relative rest
      1. Avoid squats and lunges
      2. Reduce Running mileage to painless distance
      3. Cross-train with biking, swimming, eliptical trainer
    2. Pain relief
      1. NSAIDs (variable efficacy)
      2. Ice Therapy
    3. See Patellofemoral Knee Exercises
      1. OrthoPFSExercises.htm
    4. Quadriceps strengthening
      1. Isometric progressive resistance Exercises
      2. Leg-sled Press (45 degree)
    5. Lower extremity Stretching Exercises
      1. Quadriceps Stretching
      2. Quadriceps strengthening
        1. Do not load knee at more than 45 degrees flexion
      3. Hamstring stretches
      4. Iliotibial Band stretches
      5. Ankle stretches
        1. Gastrocnemius muscle
        2. Soleus muscle
    6. Shoe modifications
      1. Replace excessively worn Running Shoes
      2. Over-pronators
        1. Running Shoe for over-pronators
        2. Anti-pronation pad
        3. Formal Orthotic
    7. Avoid provocative factors
      1. Limit weight on a flexed knee
      2. Consider cross-training activity
      3. Reduce mileage and pace
      4. Avoid uphill and downhill Running
    8. Patellar Taping (inconsistent evidence of benefit)
      1. Wittingham (2004) J Orthop Sports Phys Ther 34:504
    9. Patellar bracing (inconsistent evidence of benefit)
      1. Lun (2005) Clin J Sport Med 15:235
  8. Management: Surgical (under 5-10% of cases)
    1. Indications
      1. Persistent symptoms >6-12 months
      2. Refractory to formal rehabilitation program
      3. Other Knee Pain causes excluded
    2. Procedures
      1. Diagnostic Knee Arthroscopy
      2. Smoothing of patella articular cartilage
      3. Lateral Release
      4. Patellar tendon relocation
  9. Course
    1. Course may be prolonged in athletes as long as 6 years
  10. References
    1. Dixit (2007) Am Fam Physician 75(2):194
    2. Fulkerson (2002) Am J Sports Med 30:447
    3. Juhn (1999) Am Fam Physician 60(7):2012
    4. Ruffin (1993) Am Fam Physician 47(1):185

Patellofemoral Pain Syndrome (C0877149)

Definition (MSH)A syndrome characterized by retropatellar or peripatellar PAIN resulting from physical and biochemical changes in the patellofemoral joint. The pain is most prominent when ascending or descending stairs, squatting, or sitting with flexed knees. There is a lack of consensus on the etiology and treatment. The syndrome is often confused with (or accompanied by) CHONDROMALACIA PATELLAE, the latter describing a pathological condition of the CARTILAGE and not a syndrome.
ConceptsDisease or Syndrome (T047)
MSHD046788
EnglishAnterior Knee Pain Syndrome, Patellofemoral Pain Syndrome, Patellofemoral Syndrome
Parent ConceptsArthropathies NOS (C0022408)
SourcesMSH
Derived from the NIH UMLS (Unified Medical Language System)



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