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Patellofemoral Syndrome
Aka: Patellofemoral Syndrome, Chondromalacia Patellae, Patellofemoral Pain Syndrome, Miserable Malalignment Syndrome, Runner's Knee, PFPS
- Epidemiology
- Most common Running Injury
- Incidence: 6% in U.S.
- Females account for 55% of cases
- Risk Factors
- Female gender
- Overuse
- Provocative activities
- Running
- Squatting
- Climbing stairs (and going downstairs)
- Mechanical factors
- Dynamic valgus (with maltracking) - see below
- Rear foot eversion
- Pes pronatus
- Patellar instability
- Quadriceps weakness
- Causes: Patellofemoral or Anterior Knee Pain
- Soft tissue causes
- Prepatellar Bursitis
- Patella Tendonitis
- Meniscus Tear
- Articular causes
- Chondromalacia Patellae
- Patella Osteoarthritis
- Osteochondritis Dissecans of the Knee
- Chondral Fracture
- Functional causes
- Patella instability
- Synovial plica
- Synovium caught between Patella and femur
- Referred pain
- Back pain
- Hip Pain
- Ankle pain
- Mechanism
- Overuse syndrome in athletes
- Sports involving Running, jumping or cutting
- Cyclist or runner going too far, too soon, too fast
- Basketball and Volleyball with repetitive jumping
- Frequent change of playing surface (grass to wood)
- Repetitive squats or lunges
- Excessively worn shoes
- Contact Sports (Football or Rugby)
- Direct impact to Patella
- Degeneration of Patella
- Chondromalacia Patellae
- Osteoarthritis of the knee
- Patella mal-tracking in the patellofemoral groove
- Asymmetric quadriceps Muscle Strength
- Vastus medialis is often weaker than other Muscle
- Patella is often pulled to the outside (J-tracking)
- Results in local wearing of the articular cartilage
- Increased risk in load bearing positions such as squatting
- Anatomic variation: Increased Q-Angle
- Increased angle between femur and tibia (Q-Angle)
- Women more often have larger Q-angle
- However Q-angle has not been consistently shown as significant risk
- On Quadriceps contraction, Patella is pushed outward
- Leads to mal-tracking of the Patella as above
- Anatomic variation: Shallow outer patellofemoral groove
- Patella prone to sublux or dislocate laterally
- Symptoms
- Anterior Knee Pain
- Pain beneath, under or peri-Patellar
- Gradually progressive general aching or grating pain
- Associated symptoms
- Stiffness
- Grinding, popping, or clicking sound on knee flexion
- Provocative factors
- Going up or down stairs, or down hills
- Running
- Squatting
- Kneeling
- Prolonged sitting with knee bent (Theater sign)
- Giving-way Sensation (reflex response to pain)
- Patellofemoral Syndrome is associated with painful giving-way
- Contrast with Anterior Cruciate Ligament Tear (ACL Tear) which is associated with painless giving-way
- Findings that make alternative diagnosis more likely
- No locking or catching (contrast with meniscal tear)
- Knee Effusion
- Knee Trauma History
- Signs
- Inspection
- Excessive pronation (over pronation) on Running gait (pes pronatus)
- Medial aspect of shoe is worn down the most
- No Knee Effusion
- Abnormal Patella alignment and tracking
- See Patella Tracking Assessment (J Sign)
- Increased Q Angle of the Knee
- Lateral knee structures tight
- Patella Glide Test
- Patella tilt test
- Hamstring tightness (predisposing finding)
- Passive Knee Extension
- Palpation
- Tender undersurface of medial or lateral Patella
- Crepitation on knee range of motion
- Provocative testing
- Positive Patellar Apprehension Test
- Knee Pain with squatting
- Dynamic Valgus
- Knee shifts into valgus position on squatting while balancing on the affected leg
- Differential Diagnosis
- See Anterior Knee Pain
- Patellar Tendinopathy
- Pain and focal tenderness at inferior Patellar pole, especially worse with jumping in Patellar Tendinopathy
- Contrast with more generalized Patellar pain, especially descending stairs in Patellofemoral Syndrome
- Imaging: Knee XRay
- Not indicated in most cases of Patellofemoral Syndrome
- Used primarily to exclude other causes of Knee Pain
- Consider for refractory symptoms after 8 weeks of management
- Indications
- Age >50 years
- Patellofemoral Osteoarthritis
- Child and Adolescent
- Osteochondritis Dissecans
- Bone Neoplasms
- Views
- Weight-bearing AP Xray
- Weight-bearing lateral Xray
- Sunrise (Axial view at 20-45 degrees)
- Management: Medical
- Relative rest
- Avoid squats and lunges
- Reduce Running mileage to painless distance
- Cross-train with biking, swimming, eliptical trainer
- Pain relief
- NSAIDs (variable efficacy)
- Ice Therapy
- Pelvic-femoral rehabilitation
- Patients with dynamic valgus should undergo PT to work hip abduction and external rotation
- See Patellofemoral Knee Exercises
- OrthoPFSExercises.htm
- Quadriceps strengthening
- Isometric progressive resistance Exercises
- Leg-sled Press (45 degree)
- Eccentric Exercises (especially for Jumper's Knee)
- Patient stands on wedge platform with toes pointing to the bottom of a down slope
- Patient then does standing knee bends to 45 degrees and then fully extends
- Lower extremity StretchingExercises
- Quadriceps Stretching
- Quadriceps strengthening
- Do not load knee at more than 45 degrees flexion
- Isometric quadriceps strengthening
- Sit on floor with affected leg straight and the unaffected leg flexed
- Towel roll placed under affected leg (optional)
- Extend the knee, pressing the towel downwards and hold for 10 seconds
- Repeat 10 repetitions in each of 3 sets
- Straight Leg Raise
- Sit on floor with affected leg straight and the unaffected leg flexed
- Slowly raise the affected leg 8 inches off floor and then return to floor (over 2-4 seconds)
- Repeat 10 repetitions in each of 3 sets
- Hamstring stretches
- Lie supine on floor
- Flex the hip to 90 degrees and grasp to hold in position
- Knee starts at 90 degrees flexion and is fully extended to 90 degrees for 30-60 seconds
- Perform twice for each leg, twice daily
- Hip adductor strengthening Exercises
- Stand with one foot on platform, step or 2x4 wood
- Keep both knees straight and extended
- Start with hips and Pelvis level with floor
- Allow the unsupported leg to slowly lower, and then raise the leg to original position
- Repeat 10 repetitions in each of 3 sets
- Iliotibial Band stretches
- Ankle stretches
- Gastrocnemius Muscle
- Soleus Muscle
- Shoe modifications
- Replace excessively worn Running Shoes
- Over-pronators
- Running Shoe for over-pronators
- Anti-pronation pad
- Formal Orthotic
- Core Muscle Strength (trunk Exercises)
- Avoid provocative factors
- Limit weight on a flexed knee
- Consider cross-training activity
- Reduce mileage and pace
- Avoid uphill and downhill Running
- Patellar Taping (Kinesiotaping)
- Inconsistent evidence of benefit
- May offer short term pain relief and improve Patellar tracking when used early in course
- Used as an adjunct to physical therapy and Exercises
- Wittingham (2004) J Orthop Sports Phys Ther 34:504-10 [PubMed]
- Callaghan (2012) Cochrane Database Syst Rev (4): CD006717 [PubMed]
- Patellar bracing
- Not generally recommended
- No significant benefit or inconsistent benefit over Exercises alone
- Despite this, use has increased in sports medicine as of 2012
- Some runners may see benefit
- References
- Lun (2005) Clin J Sport Med 15:235-40 [PubMed]
- Swart (2012) Br J Sports Med 46(8): 570-77 [PubMed]
- Management: Surgical (under 5-10% of cases)
- Indications
- Persistent symptoms >6-12 months
- Refractory to formal rehabilitation program
- Other Knee Pain causes excluded
- Procedures
- Diagnostic Knee Arthroscopy
- Smoothing of Patella articular cartilage
- Lateral Release
- Patellar tendon relocation
- Efficacy
- Arthroscopy adds no benefit over home Exercise in Patellofemoral Pain Syndrome
- Kettunen (2007) BMC Med 5:38 [PubMed]
- Course
- Course may be prolonged in athletes as long as 6 years
- References
- Arnold (2018) Am Fam Physician 97(8): 510-6 [PubMed]
- Childress (2013) Am Fam Physician 87(7): 486-90 [PubMed]
- Dixit (2007) Am Fam Physician 75(2):194-204 [PubMed]
- Fulkerson (2002) Am J Sports Med 30:447-56 [PubMed]
- Gaitonde (2019) Am Fam Physician 99(2): 88-94 [PubMed]
- Jones (2015) Am Fam Physician 92(10): 875-83 [PubMed]
- Juhn (1999) Am Fam Physician 60(7): 2012-8 [PubMed]
- Ruffin (1993) Am Fam Physician 47(1): 185-94 [PubMed]