Patellofemoral Syndrome

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

1. Epidemiology
   1. Most common Running Injury
2. Causes: Patellofemoral or anterior Knee Pain
   1. Soft tissue causes
      1. Prepatellar Bursitis
      2. PatellaTendonitis
      3. Meniscus Tear
   2. Articular causes
      1. Chondromalacia Patellae
      2. PatellaOsteoarthritis
      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. Grinding, popping, or clicking sound on knee flexion
   6. No locking or catching
      1. Contrast with meniscal tear
   7. Provocative factors
      1. Going up or down stairs, or down hills
      2. Running
      3. Squatting
      4. Prolonged sitting with knee bent (Theater sign)
   8. Giving-way sensation (reflex response to pain)
      1. Patellofemoral Syndrome is associated with painful giving-way
      2. Contrast with Anterior Cruciate Ligament Tear (ACL Tear) which is associated with painless giving-way
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
   4. Dynamic Valgus
      1. Knee shifts into valgus position on squatting while balancing on the affected leg
6. Imaging: 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. Pelvic-femoral rehabilitation
      1. Patients with dynamic valgus should undergo PT to work hip abduction and external rotation
   4. See Patellofemoral KneeExercises
      1. OrthoPFSExercises.htm
   5. Quadriceps strengthening
      1. Isometric progressive resistance Exercises
      2. Leg-sled Press (45 degree)
   6. Lower extremity StretchingExercises
      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
   7. Shoe modifications
      1. Replace excessively worn Running Shoes
      2. Over-pronators
         1. Running Shoe for over-pronators
         2. Anti-pronation pad
         3. Formal Orthotic
   8. 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
   9. Patellar Taping
      1. Inconsistent evidence of benefit
      2. May offer pain relief
      3. Wittingham (2004) J Orthop Sports Phys Ther 34:504-10
   10. Patellar bracing
       1. Inconsistent evidence of benefit
       2. Appears effective in runners
          1. Use has increased in sports medicine as of 2012
       3. Lun (2005) Clin J Sport Med 15:235-40
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):194-204
    2. Fulkerson (2002) Am J Sports Med 30:447-56
    3. Juhn (1999) Am Fam Physician 60(7): 2012-8
    4. Ruffin (1993) Am Fam Physician 47(1): 185-94