Patellofemoral Pain Syndrome (PFPS)

Question 1

Potential causes of patellofemoral pain

Answer 1

• frequent & excessive loading (unaccustomed)
• biomechanical
• ischemic mechanism
• pain science: centralized pain response
• females > males

Question 2

Demographics and extrinsic factors for patellofemoral pain

Answer 2

• 12-17 years old, female, and higher BMI
• rapid changes in training intensity, altered training surfaces, incorrect/overused footwear, high frequency LE overload

Question 3

Intrinsic factors for patellofemoral pain

Answer 3

• strength
• path-mechanical
• neuromuscular control
• flexibility
• psychosocial factors: social support, poor self perceived health, mental distress, & catastrophizing
• centralized pain response

Question 4

Arthrokinematics of the patella

Answer 4

• provides biomechanical advantage to the quad extensor mechanism
• joint stress is dissipated by thick hyaline cartilage covering the patella’s undersurface
• full knee extension = no patella contact with femur
• patellofemoral joint reaction force = angle dependent, force of the quads & patella tendon at the patellofemoral joint contact area

Question 5

Causes of patella femoral joint malalignment

Answer 5

• Bony morphology: trochlear dysplasia can lead to excessive lateral tilt & lateral malalignment of the patellofemoral joint, decreasing contact area & increasing stress
• Tight lateral structures: excessive tightness of lateral reticular structures has been associated with increased lateral compression of the patellofemoral joint, ITB tightness due to distal fibers merging with superficial & deep fibers of the lateral retinaculum
• patella atlas can increase patellofemoral contact force & stress upon knee flexion

Question 6

Possible proximal mechanisms for PF tracking

Answer 6

• patellofemoral joint reaction force based on angle dependent force of the quads & patellar tendon
• motions originating at the hip during functional activities may result in laterally directed patellofemoral joint contact
• can be attributed to femoral IR under a stable patella
• recent perspective is increased femoral IR

Question 7

Possible distal mechanisms for PT tracking

Answer 7

• excessive ER of the tibia may also influence lateral facet compression of the patella
• rotational force is applied to the patella at the inferior pole via the patellar tendon

Question 8

Pathogenesis PFPS

Answer 8

• frequent & excessive loading of the patellofemoral joint & the surrounding tissue outside the joint’s “envelope of function” can induce loss of musculoskeletal tissue homeostasis, generating pain
• Possible inflammation in: patellar fat pad, synovium, patellofemoral ligaments, quadriceps tendon, patellar tendon, & subchondral bone

Question 9

Screening to rule out other causes of patellar pain

Answer 9

• teninopathy of patellar/quads
• apophysitis
• ITB syndrome
• pes anserine bursitis
• pre patellar bursitis/Hoffa disease
• ligamentous instability
• meniscus tear
• bipartite patella
• space occupying lesion
• osteoarthritis
• neuroma
• patellar condromalacia
• plica syndrome
• lumbar radiculopathy
• saphenous neuritis

Question 10

Outcome measures

Answer 10

• lower extremity functional scale (LEFS)
• knee outcome survey: ADL scale

Question 11

Impairment of body function

Answer 11

• pain in joint
• impaired ROM of single joints: patellofemoral mobility, knee/hip/ankle DF limitations
• impaired power production: quads, hamstrings, hip, ankle, pelvic/core
• soft tissue restrictions: iliopoas, rectus remoras, hamstrings, ankle PF muscles, ITB lateral patellar retinaculum

Question 12

Functional assessments

Answer 12

• single limb balance: excessive Trendelenburg, femoral ADD & IR, ips knee ABD, trunk sway, & foot pronation
• double leg squat: quad dominant, decreased DF with anterior COM
• single leg squat

Question 13

Interventions for therapeutic exercises

Answer 13

• focus on hip strength in open & closed chain focusing on hip ADD, extensors, ER, & core strength
• initial exercises should limit compressive patellofemoral joint forces (hip focus)

Question 14

Quad strengthening considerations for PFJ stress

Answer 14

• squatting at 90 degrees, 75 degrees, & 60 degrees of knee flexion = higher PFJ stress when compared to open chain
• open chain exercises at 30, 15, & 0 degrees of knee flexion = higher PFJ stress when compared to double leg squatting
• eccentric step downs must be pain free
• no need to isolate the VMO

Question 15

Compressive forces on the knee

Answer 15

• Closed chain squat: forces increase until 90 degrees then levels off or decreases
• Open chain weighted extremity: greatest JRF occurs at about 30-0 degrees of knee flexion

Question 16

Common quad exercise prescriptions seen in rehab

Answer 16

• Open kinetic chain exercises from 90 degrees knee flexion to about 60 degrees knee flexion
• closed chain exercises (mini squat) initially started 0-30 degrees then progressed as patient tolerates

Question 17

Interventions neuromuscular reeducation

Answer 17

• movement education
• task specific practice
• squatting mechanics
• running training

Question 18

Interventions stretching/manual therapy

Answer 18

• Manual therapy: patella mobs, tibiofemoral joint mobs, & talocrural joint mobs
• Soft tissue mobilization: quads, retinaculum, talocrural joint, iliopoas, TFL/ITB complex

Question 19

Interventions bracing/taping

Answer 19

• Bracing: may provide symptom reduction by increasing the patellofemoral contact area
• Taping: little to no change in patellar alignment, may alter proprioceptive input & increase tolerance to functional training

Question 20

Prevention: reduction of loading to the patellofemoral joint

Answer 20

• decrease running miles/volume
• avoid breast stroke kick in swimmers
• decrease volume of cutting/jumping sports
• avoid activities that involve excessive & deep squatting, or other prolonged knee flexion activities

Question 21

Surgical interventions

Answer 21

• Lateral release: arthroscopic release is currently reserved only for patients with an excessively tight lateral retinaculum & associated lateral tilt of the patella
• Proximal realignment: proximal reconstruction of the medial patellofemoral ligament
• Distal realignment: medial tibial tubercle transfer or an anteromedial tibial tubercle transfer