1. Differential Dx
1.1. Knee OA
1.1.1. 10% men and 13% women > 60yo
1.1.2. > 45 yo*
1.1.3. Morning stiffness < 30 minutes
1.1.4. Activity-related joint pain
1.1.5. Crepitus
1.1.6. Boney enlargement
1.1.7. No palpable warmth
1.1.8. R/O RA
1.2. Patellar tendinopathy
1.2.1. Pain localized to the inferior pole of the patella
1.2.2. Pain with prolonged sitting, squatting and stairs
1.2.3. Load-related pain that increases with the demand on the knee extensors
1.2.4. Instant tendon pain with loading, relieved immediately upon removal of load
1.2.5. Pain may improve with repeated loading
1.2.5.1. "Warm-up" phenomenon
1.2.6. Absence of pain at rest
1.3. Hoffa's fat pad syndrome
1.3.1. Diffuse anterior-inferior knee pain
1.3.2. Tibiofemoral hyperextension incident or repetitive trauma
1.3.3. Male, young athletes, middle-aged
1.3.4. Pain at end-range knee extension
1.3.5. Pain with digital pressure applied directly to the fat pad
1.3.5.1. Hoffa test
1.3.6. MRI
1.3.7. Increased risk of knee OA
1.3.8. Moderate joint effusion and periligamentous swelling may be present
2. Conservative and Medical Interventions
2.1. Surgical - addresses structural malalignment, which is a rare cause of PFPS
2.1.1. Fulkerson Procedure (Tibial Tuberosity Transfer)
2.1.2. Patellofemoral Debridement
2.1.3. Lateral Retinaculum Release
2.2. Conservative
2.2.1. Symptom-Modulated Rehab
2.2.1.1. Load Management/Modification
2.2.2. Bracing
2.2.2.1. not recommended
2.2.3. Patellar Taping
2.2.3.1. use in combination with exercise
2.2.3.2. beneficial in short term
2.2.4. Footwear
2.2.4.1. Orthoses
2.2.4.1.1. Pre-fabricated > custom
2.2.4.1.2. useful if greater than normal foot pronation
2.2.4.1.3. short term benefits
2.2.5. Biofeedback
2.2.5.1. EMG for VMO training
2.2.5.1.1. not recommended
2.2.5.2. Visual during hip and knee exercises
2.2.5.2.1. not recommended
2.2.6. Manual Therapy
2.2.6.1. Dry Needling
2.2.6.1.1. not recommended
2.2.6.1.2. accupuncture may be used to manage pain
2.2.6.2. Mobilizations/Manipulations
2.2.6.2.1. should not be used in isolation
3. Early and Late phase exercises
3.1. Early Phase
3.1.1. Quadriceps
3.1.1.1. OKC 90-45 deg of knee flexion
3.1.1.1.1. LAQ
3.1.1.1.2. Knee extension machine
3.1.1.2. CKC 0-45 deg of knee flexion
3.1.1.2.1. Mini squats
3.1.1.2.2. Step-ups
3.1.1.2.3. Box squats
3.1.1.2.4. Goblet squats
3.1.2. Hip
3.1.2.1. Step ups
3.1.2.2. Bridges
3.1.2.3. Sidelying hip abduction
3.1.3. Trunk
3.1.3.1. Planks
3.1.3.2. Side planks
3.1.4. Balance
3.1.4.1. Static SLS
3.1.4.2. SLS with anticipatory postural control
3.1.4.2.1. SLS with trampoline ball toss
3.2. Late Phase
3.2.1. Quadriceps - increase ROM
3.2.1.1. LAQ
3.2.1.2. Knee extension machine
3.2.1.3. Anterior step downs
3.2.1.4. Heels-elevated goblet squats
3.2.1.5. SL Box Squat
3.2.1.6. Split squats
3.2.2. Hip
3.2.2.1. SL Bridges
3.2.2.2. Feet elevated bridges
3.2.2.3. Hip abduction planks
3.2.2.4. Hip thrusts
3.2.2.5. Lateral lunges
3.2.2.6. Resisted hip abduction
3.2.3. Trunk
3.2.3.1. Planks with shoulder taps
3.2.3.2. Split stance Palloff press
3.2.3.3. Hip abduction planks
3.2.4. Balance
3.2.4.1. SLS dual tasking
3.2.4.2. SLS with reactive postural control
3.2.4.2.1. External perturbation
3.2.4.2.2. Unstable load
3.2.5. Plyometrics Progression
3.2.5.1. SL hopping
3.2.5.2. SL lateral bounds
3.2.5.3. Box jumps
3.2.5.4. Broad jumps
3.2.5.5. SL broad jump
3.2.5.6. Depth drop
3.2.5.7. Depth drop to broad jump SLS
4. Prevalence/Incidence
4.1. Prevalence
4.1.1. Most frequently cited at 25% of idiopathic knee pain but can range from 3% to 85%
4.1.1.1. professional cyclists 35.7%
4.1.1.2. general adolescent population 28.9%
4.1.1.3. female amateur athletes 22.7%
4.1.2. Highest in ages 12-19 and ages 50-59
4.1.3. Females more often than males
4.1.4. 1.5% and 7.3% of all patients seeking medical care.
4.2. Incidence
4.2.1. 9.66 per 100 adolescent female athletes
5. Risk factors
5.1. Anatomic anomalies
5.1.1. Hypoplasia of the medial patellar facet
5.1.2. Patella alta
5.2. Training errors or overuse
5.3. Malalignment & altered biomechanics of the LE
5.4. Tight lateral structures
5.4.1. Lateral reticaculum
5.4.2. Iliotibial band
5.5. Muscle dysfunction
5.5.1. Quadriceps weakness
5.5.2. Improper firing pattern
5.6. Decreased flexibility
5.6.1. Hamstrings
5.6.2. Quadriceps
5.6.3. Iliotibial band
5.7. Trauma
5.8. Female
6. Assessment
6.1. History
6.1.1. anterior knee pain; behind, underneath or around patella
6.2. Lower quadrant screen
6.3. Special Tests
6.3.1. Patellar tilt test
6.3.2. Patellar grind test
6.3.3. Medial or lateral patellar facet tenderness
6.3.4. Patellar apprehension test
6.3.4.1. rules in hx of dislocation
6.4. Physical Findings
6.4.1. Pain during squatting
6.4.1.1. Sn: 0.91-0.94; Sp: 0.46-0.50; +LR: 1.7-1.8; -LR: 0.1-0.2
6.4.2. Pain with stair climbing
6.4.2.1. Sn: 0.75-0.94; Sp: 0.43-0.45; +LR: 1.7; -LR: 0.3
6.4.3. Pain with kneeling
6.4.3.1. Sn: 0.84; Sp: 0.50; +LR: 1.7; -LR: 0.3
6.4.4. Palpation
6.4.4.1. tenderness, crepitous
6.4.5. Multiangle isometric quad testing
6.5. Outcome measures
6.5.1. Anterior Knee Pain Scale
6.5.2. Functional Index Questionnaire
6.5.3. Patellofemoral Pain Syndrome Severity Scale
6.6. Cluster to Include
6.6.1. Cluster 1
6.6.1.1. Age over 40yo
6.6.1.2. Isolated Anterior Knee Pain OR Medial patellar facet tenderness
6.6.2. Cluster 2
6.6.2.1. Age 40-58
6.6.2.2. Isolated anterior or diffuse knee pain
6.6.2.3. Mild to moderate difficulty discending stairs
6.6.2.4. Medial patellar facet tenderness
6.6.2.5. Full passive knee extension
6.7. Cluster to Exclude
6.7.1. Cluster 1
6.7.1.1. age <58 yo
6.7.1.2. Medial, lateral, or posterior knee pain
6.7.1.3. No medial or lateral patellar facet tenderness
6.7.2. Cluster 2
6.7.2.1. age <58 yo
6.7.2.2. diffuse or lateral knee pain
6.7.2.3. Medial or lateral patellar facet tenderness
6.7.2.4. Restricted passive knee extension
6.7.3. Cluster 3
6.7.3.1. age <58 yo
7. Prognosis
7.1. Good-excellent results in 4-6 weeks
7.1.1. Low pain catastrophizing
7.1.2. Decreased frequency of pain
7.1.3. Low fear avoidance
7.1.4. High AKPS score
7.2. Unsuccessful predictive factors
7.2.1. knee pain lasting more than four months
7.2.2. older age
7.2.3. higher baseline pain severity
7.2.4. lower patient reported function on AKPS
8. Bonus Content - Clinical Pearls
8.1. The recurrence of PFP is alarmingly high with 70-90% having recurrent symptoms
8.1.1. More than 50% of individuals diagnosed with PFP will report unfavorable outcomes 5 to 8 years after
8.2. Strengthening of the quadriceps and glutes is key
8.2.1. Too much focus on activation of the VMO should be avoided as there is no evidence to suggest it can be isolated
8.3. This is not a self-limiting condition
8.4. Boney alignment and Q-angle does not correlate with pain
8.5. PFPS is not the result of patella moving on the femur, but is associated with the femur internally rotating underneath the patella
8.5.1. Functional hip weakness is the issue rather than boney alignment