Considerations for the
Management of
Patellofemoral Dysfunction
Ibrahim Altubasi, PT, PhD
Physical Therapy Department
The University of Jordan
Patellofemoral Biomechanics:
Function of the Patella
Increase the
moment arm of the
quadriceps
(extensor
mechanism)
Provide anterior
protection of tibio-
femoral joint
Patellofemoral Biomechanics:
Estimated Forces on the PF Joint during
ADLs
Walking: 0.5 times body weight
Stair climbing: 3.3 times body weight
Deep Knee Bends: 8 times body weight
Reilly DT, Martens M: Acta Orthop Scand, 1972;
43: 126
Patellofemoral Biomechanics:
Patellofemoral Contact Areas
Area goes from
distal to proximal on
surface of patella as
the knee is flexed
Area becomes
larger as knee is
flexed
Powers CM, et al, Med Sci Sports Exerc.
2004;36:1226-1232
Data indicate that there is contact between the patella
and femur at 0.
PF Contact area calculated from MRI data
Patellofemoral Biomechanics:
Joint Reaction Forces
Quadriceps force
creates patellofemoral
compression force
Magnitude of force
changes with knee
flexion angle
Pattern different
between wt bearing and
non-wt. bearing
conditions
Patellofemoral Biomechanics:
Joint Reaction Forces During Open
Chain Leg Extension, Free Weight
Increased flexion moment arm of gravity or external
resistance
Increased quadriceps force
PFJR force peaks at 350
Decreased contact area results in increasing contact
stress from 90 to 200 of flexion
Moment Arm of
Gravity
Patellofemoral Biomechanics:
Joint Reaction Forces During Closed
Chain Knee Flexion (Squat)
Increased flexion moment
arm of gravity or external
resistance
Increased quadriceps force
Increased PFJR
Increased contact area
partially off-sets increasing
PFJR to minimize increase
in contact stress
Patellofemoral Biomechanics: PF
Contact Stress During Open and Closed
Chain Knee Extension and Flexion
PFJR & contact stress
greater with OKC from 0
to 450 (Free weight)
PFJR & contact stress
greater with CKC from
45 to 900
Steinkamp, et al, Am J Sports Med, 1993
Patellofemoral Biomechanics: PF
Contact Stress During Open Chain Knee
Extension Using a Cam-Device for
Resistance
How would the PF contact forces differ
throughout the range when using a
cam-device vs a free weight to provide
the resistance in the leg extension
exercise?
Open Chain Knee Extension: Free weight
vs Using a Cam-Device for Resistance
Free
Weight
Condition
Moment
Arm of
Gravity Moment
Arm of
Gravity
Cam-
Moment
Device Arm of
Condition Gravity
Moment
Arm of
Gravity
Patellofemoral Biomechanics: PF
Axial Strain During Isometric Quadriceps
Contractions at Varying Angles of Knee
Flexion
There is greater axial
strain on the patella
in greater degrees of
knee flexion
What are the
implications for
rehabilitation of
BPTB autograft Sharkey NA, et al, Arch Phys Med
patients Rehabil, 1997.
Patellofemoral Alignment:
Superior/Inferior
Fused
Epiphyseal
Plate Line
Blumensatt’s
Line
Insall-Salvati: 1:1 ratio of
patellar length and patellar Patella should sit
tendon length. Normal ratio between these two lines.
range from 0.8 to 1.2
Patella Alta and Baja (Inferna)
Alta Baja
Patellofemoral Alignment: Frontal
Plane Rotation (Patellar Tilt)
Excessive lateral tilt
may occur from
shortening of lateral
retinacular tissue,
ITB, etc.
Oatis CA. Kinesiology: The Mechanics &
Pathomechanics of Human Movement.
Lippincott, Philadelpia, PA 2004.
Patellofemoral Tracking
Inferior with flexion
Superior with
extension
Also some medial
and lateral gliding
occuring with inferior
and superior gliding
Effect of the Quadriceps on
Patellofemoral Tracking
Compressive load
from quad
contraction creates
stability
VMO functions to
counter lateral
vector from
remainder of quads
(Lieb and Perry 79)
Where Does Patellofemoral Pain
Come From?
Cartilage? Chondromalacia vs
Patellofemoral Chondrosis
aneural, no pain fibers
Some patients with cartilage degeneration do
not have pain, others with no cartilage
degeneration do have pain
Perhaps pain related to cartilage degeneration
may actually be from subchondral plate, which
is innervated
Where Does Patellofemoral Pain
Come From?
Retinacular Tissues?
Excessive tension on lateral retinaculum may
cause irritation or inflammation
Fulkerson (1985) reported neuromatous
degeneration of small nerve fibers in tight
lateral retinacular tissue
Where Does Patellofemoral Pain
Come From?
Other Possibilities
Patellar tendon, fat pad
Medial Plica
Osteochondral Lesions
Synovial impingement (Odd facet syndrome)
Patellofemoral Dysfunction
Blunt Trauma
Malalignment or Mal Tracking
Excessive Compression
Patellofemoral Dysfunction
Anterior knee pain
Usually gradual onset
Painful Activities
ascending and descending stairs
prolonged positioning with knee flexed
jumping, quick stop and starts
More common in adolescent females
Also common in young and middle-aged active
adults
Differential Diagnoses
Medial Plica Syndrome
Meniscal Injury
Patellar Tendon/Fat Pad Injury
Quadriceps Tendon Injury
IT Band Syndrome
Osteochondritis Dissecans/Chondral
Fracture
PCL injury
P-F Dysfunction: Contributing
Factors
Bony Structural Abnormalities
Soft Tissue Restrictions
Quadriceps Femoris Dysfunction
Hip Abductor/External Rotator Weakness
Flattened Lateral Condyle
Patella Alta
Patella Inferna (Baja)
Lower Extremity
Malalignments
Restricted Lateral Restraints
Soft Tissue Restrictions:
ITB Tightness
Restricted Rectus Femoris
Restricted Hamstrings
Restricted Gastrocnemius
Quadriceps Femoris
Dysfunction
Open vs. Closed Chain
Exercise
PFJR & contact stress greater with OKC from 0 to 450
PFJR & contact stress greater with CKC from 45 to 900
General LE Stengthening Ex
Early Rehab Later Rehab (PRE)
quad sets Leg extensions 90-
SLR 45
Leg Press 0-45
1/2 squats
Leg Curls 0-90
Lateral step ups
leg extensions with
cuff weights 90-45
Hip Abduction/Lateral Rotation
Weakness
May result in excessive medial
rotation of femur during stance
May result in excessive valgus at
knee
May increase Q angle
May result in tracking and alignment
problems
Powers CM, JOSPT, 2003
Non-Wt bearing, patella displaces on femur
Wt- bearing, femur rotates under patella
Need to control hip in patients who collapse into
valgus
S.E.R.F. StrapTM Patellofemoral
Brace
S – Stability thru
E – External
R – Rotation of the
F - Femur
Hip Weakness in PFP Syndrome
Ireland, et al, JOSPT, 2003 Piva, et al, JOSPT, 2005
15 ♀ with PFP and 15 Control 30 with PFP and 30 Control
SIDE-LYING ABDUCTION
ABDUCTION WITH PILATES
DEVICE
Single leg hip and pelvic control
Reverse Action Hip Single Leg Lateral Step
Abduction Down
RESISTED STANDING
EXTERNAL ROTATION
Patellofemoral Taping Techniques
Medial Glide
Correction of
lateral
displacement
Patellofemoral Taping Techniques
Medial Tilt
Correction of
lateral
compression
Patellofemoral Taping Techniques
Medial Rotation
Correction of
excessive lateral
rotation
General Treatment Guidelines for
PF Dysfunction
Foot orthotics if associated with sx
Stretching of restricted soft tissues
Strengthening of quads in limited arc
Strengthening of hip abd/later rot
Functional activity modifications
Patellar taping or bracing
IT Band Syndrome (Runner’s Knee):
Traditional Mechanism
Pain and irritation of IT
band from increased
friction over lateral
femoral epicondyle.
Common in distance
runners.
Posterior fibers of ITB
impinge on lateral
femoral condyle at about
30 degrees of knee
flexion, due to tightness
Fredericson and Wolf, 2005
IT Band Syndrome (Runner’s Knee):
Potential Contributing Factors
Running in one direction around track
Excessive downhill running
Reduced eccentric strength for breaking
forces of LE
Weak hip abductors (less control of hip
adduction moment during wt bearing,
places more tension through ITB)
Shortened ITB complex
Fredericson and Wolf, 2005
IT Band Syndrome (Runner’s Knee):
Alternative Mechanism: Fairclough, 2006
ITB is fixed to femur distally through fibrous
strands, so it doesn’t really move back and
forth across the femoral condyle (cadaveric
study).
Adipose tissue that is rich in neurovascular
structures fills gap between ITB and
epicondylar region.
IT Band Syndrome (Runner’s Knee):
Alternative Mechanism: Fairclough, 2006
ITB insertion on tibia
more lateral relative
to femur in full
extension than at
30
ITB may compress
fat pad at 30
resulting in
increased pain and
irritation.
Extended Flexed 30
IT Band Syndrome
(Runner’s Knee)
Anterior, lateral knee pain, gradual onset,
associated with running or walking, descending
stairs
Tenderness over anterior tibial tubercle (Gerdy’s)
and/or lateral retinaculum, lateral femoral
epicondylar region
Increased skin temp and swelling
+ Ober’s test, modified thomas test +
Symptoms reproduced with knee flexion/ext,
resisted contraction of tensor facia latae
General Treatment Approach for
ITB Syndrome
Stretching of ITB
Modified Thomas Position
Ober’s position
Medial patellar glide
Combination
Soft tissue mobilization techniques
Strengthening of hip abductors
Anti-inflammatory treatment if signs of
inflammation are present (ice, NSAIDS)
Function of the Patellar Tendon
Transmits loads from the
extensor mechanism to the
tibia.
Must transmit high loads
during propulsion phases
of running, jumping, heavy
lifting.
Must absorb heavy loads
on landing from a jump,
sudden stops, sudden
changes in direction.
Patellar Tendinitis/Tendinosis
(Jumper’s Knee)
Pain and irritation of patellar tendon
Gradual onset of pain, associated
with jumping, quick stops, sprinting
Tenderness, skin temp and
swelling
Pain reproduced with resisted quad
contraction or passive stretching of
quads.
Tendonitis vs Tendinosis
Tendonitis
Implies presence of inflammation with pain
and sometimes weakness
May respond to anti-inflammatory
treatment
Tendinosis
Implies degenerative change in tendon
May have pain and weakness, but no
clinical or histological signs of inflammation
Will not respond well to anti-inflammatory
treatment
Extrinsic Factors Contributing to
Patellar Tendinosis
Reduced Quadriceps and Hamstring
Flexibility (Witvrouw, et al, Am J Sports Med.
2001;29:190-195)
Training Errors (Ferretti, et al. Sports Med.
1986;3:289-295)
Intensity, Frequency, Duration
Training surfaces
Patellar Malalignment/Maltracking? (Peers
KHE, Lysens RJJ. Sports Med. 2005;35:71-87.)
Conflicting evidence for this issue
General Rehab Approach for
Patellar Tendinosis.
Flexibility of Quadriceps and Hamstrings
Relative Rest During Symptomatic Periods
to Allow for Tissue Healing
Strengthening of the Quadriceps
(eccentrics)
Patellar Mobility/Taping/Bracing?
Osgood-Schlatter Disease
Partial or complete
avulsion of growing
tibial tubercle
Boys more commonly
affected than girls
Usually occurs when
participating in
jumping, cutting,
running activities
Osgood-Schlatter Disease
Pain in region of tibial tubercle
Aggravated with jumping, squatting, and
kneeling
May lead to patella alta
Usually treated conservatively, pain
dictating degree of participation in sports
Generally resolves in 12-18 months
Sinding-Larsen-Johansson
Disease
Persistent traction on
immature inferior pole
leading to calcification
and ossification
More common in boys
Usually occurs when
participating in
jumping, cutting,
running activities
