patellofemoral pain syndrome (pfps)
TRANSCRIPT
By- Priyanka Urkurkar
PATHOMECHANICS OF PATELLOFEMORAL
PAIN SYNDROME (PFPS)
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contents
PATELLOFEMORAL
ANATOMY
BIOMECHANICS
JOINT PAIN
PATHOMECHANICS
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Anatomy of patellofemoral joint Patella is the flat triangularly
shaped largest sesamoid bone
in the body
• It is embedded within the
quadriceps muscles
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Posterior articular surface
Medial facet lateral facet odd facet
Divided by a vertical
ridge
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Attachments of the patella 24-feb-13Priyanka Urkurkar
Joint congruence
Patella has much smaller articular surface than its
femoral counterpart.
Thus it is one of the most incongruent joints of
the body.
In an extended knee joint congruency is minimal.
Stability is affected mainly by vertical position of
patella
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Also, vertical position of the patella is related to the
patellar tendon
Insall-Salviti index : length of patellar tendon to the
length of patella is approximately 1:1
Patella alta : abnormally high position of patella on
femoral sulcus.
Patella baja : patella sits lower than normal on
femoral sulcus and positioned more inferiorly24-feb-13Priyanka Urkurkar
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Biomechanics of Patellofemoral joint
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Motion of the patella
Flexion and extension
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Medial and lateral patellar tilt
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Medial and lateral rotation of the patella
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Patellofemoral jointstress
PFJ can undergo very high stress during typical
activities of daily living.
PFJ reaction force is influenced by both quadriceps
force and knee angle.
During knee flexion and extension patella is pulled
superiorly by quadriceps tendon and inferiorly by
patellar tendon.24-feb-13Priyanka Urkurkar
Combination of these pulls produces posterior
compressive forces of patella on femur
It varies with knee flexion
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In extension, there is small contact area between
patella and femur.
Minimal posterior compressive vectors of vastus
medialis and vastus laterails muscles maintains low
joint stress
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Frontal plane Patellofemoral joint stability
It is unique in its potential for
Frontal plane instability near full extension
Degenerative changes resulting from PFJ stress
Relative stability depends on
Transverse stabilizers
longitudinal stabilizers
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Longitudinal stabilizers
Quadriceps tendon
Patellar tendon
Patello – tibial ligament
capsule
It provides medial lateral stability of patella in
knee flexion
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Patellar
tendon
Quadrice
ps
tendon
Articular
capsule
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Transverse stabilizers
Superficial portion of extensor retinaculum
Medial and lateral patellofemoral ligament
attach the patella to the adductor tubercle
medially and IT band laterally.
Large lateral lip of the femoral sulcus
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Quadriceps Force Vector
The quadriceps force vector includes forces from
the fiber orientation of
vastus lateralis (VL) - composed of two force
vector components ,
o the vastus lateralis longus (VLL)
ovastus lateralis obliquus (VLO).
vastus intermedius (VI), 24-feb-13Priyanka Urkurkar
rectus femoris (RF),
vastus medialis (VM) – composed of two force
vector components
the vastus medialis longus (VML)
vastus medialis obliqus(VMO)
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Patellar tracking
The patellofemoral joint functions to increase the
efficiency of knee extensor mechanism by :
Increasing the distance of the extensor apparatus from the
axis of the knee
Increasing the length of the quadriceps moment arm
Turning the force of quadriceps directed obliquely
superiorly and slightly laterally into a strict vertical force
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Tracking of the patella is mainly due to
configuration of femoral condyles and contracting
surfaces of the patella.
And, to a lesser extent due to Q angle.
If underlying bony structural alignment is poor,
prognosis of the treatment is likely to be poor.
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Patella Maltracking
The patella sits at the front of the knee, and with knee
flexion and extension it normally runs up and down the
middle of a groove in the front of the knee, called the
trochlear groove.
For various reasons the patella can track out of its
groove (usually pulled laterally).
This is called patellar maltracking.
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It is usually an overuse type injury, but can be a result
of trauma to the knee (subluxation or dislocation)
With patellar maltracking, patella will rub, and there
forces on the articular cartilage surfaces (in the
patellofemoral joint) will be increased.
This can cause pressure overload and pain, and
eventually the articular cartilage can suffer increased
wear and tear.
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The direction of quadriceps
force produces a measure
known as Q – angle
Increases with femoral
anteversion and/ or external
tibial torsion
The Q - angle
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Q – angle for male and female
•The average angle is
• 15.8 ± 4.5 for females
•11.2 ± 3.0 for men
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Above 15 degrees is considered excessive in men
Above 17 degrees is considered excessive in
females
This is indicative of severe patellar malalignment.
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What is patellofemoral pain syndrome ?? It’s a preferred term used to describe peripatellar
and retro patellar pain
Synonyms
Patello femoral joint pain
Anterior knee pain
Chondromalacia patella
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patellofemoral pain syndrome
Usually young ( adolescents) and active
Young athletes
Pain on sitting (movie-goer sign)
Middle aged Female > Male (2.2 times)
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Clinical signs of PFPS
Signs PFPS
Onset running, stair/step activity particularly
eccentric component
Pain peripatellar and/or posterior, hard to
describe
Tenderness peripatellar or inferior pole, may not be
palpable
Crepitus often present in severe cases
Giving way due to quads weakness or pain
Effusion occasional but small 24-feb-13Priyanka Urkurkar
Click clunk often in older athlete
Knee ROM decreased in severe cases
Patellar mobility dec. medial glide due to
tight lateral retinaculum
VMO wasting VMO/ VL
imbalance and altered timings
Effect of activity pain increases with inc. in
activity
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How does PFJ load results in patellofemoral pain ??
Injury to PFJ musculoskeletal tissues by
supraphysiological load
Single maximal load
Lower magnitude repetitive load
Cascade of events occur
Inflammation of the peripatellar bone stress
synovium24-feb-13Priyanka Urkurkar
Patello femoral joint pain
Increase in PFJ load causes patellofemoral pain.
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Extrinsic load is created by ground reaction forces
Is moderated by –
Body mass
Speed of gait
Surfaces
foot wear
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Intrinsic load is conceptualized as patella tracking
Factors influence patella tracking
Remote
Local
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REMOTE FACTORS
Femoral internal
rotation
Knee valgus
Tibial rotation
Subtalar pronation
Muscle strength
Muscle inflexibility
LOCAL FACTORS
Patella position
Soft tissue tension
Neuromuscular
components of the
medial and lateral
vasti
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Contributing factors for PFPS
1. Remote factor
Increased femoral -structural: femoral anteversion
internal rotation -weak external rotators and hip
abductors
-ROM deficit in the hip
Increased Knee valgus -structural: genu varum, tibial
varum,, coxavarum
-weak hip external rotators,
abductors, quadriceps and
hamstrins
Subtalar pronation
Muscle flexibility -rectus femoris, TFL, quads,
hamstrings and gastocnemius24-feb-13Priyanka Urkurkar
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Contributes to poor tracking of the patella
Allows vastus lateralis to pull the patella laterally
VMO weakness
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Causes lateral tilt of the patella
Lateral patellar facet compression
Pain in lateral aspect of knee
Non-contact of the medial patellar facet
Chondromalacia of medial
patellar facet
Tight Lateral Patellar Retinaculum:
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Pes planus
Foot pronation is a combination of eversion,
dorsiflexion and abduction of the foot
Hyper pronation with a secondary increase in
transverse plane motion of the tibia leads to
eccentric loading of the patella
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This includes overuse of vastus lateralis and
underuse of VMO
Thus, it causes compensatory internal rotation of
tibia or femur
Upsets the patellofemoral mechanism
Leading to patellofemoral pain
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Pronated feet 24-feb-13Priyanka Urkurkar
Pes Cavus
High-Arched or supinated foot.
Compared with a normal foot, a high-arched foot
provides less cushioning for the leg when it strikes the
ground.
This places more stress on the patellofemoral
mechanism, particularly when a person is running.
Causing the patella shift more laterally
Am Fam Physician. 1999 Nov 1;60(7):2012-2018.
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2. Local factors
Patella position
Patella position structural observation
Lateral displacement -patella displaced laterally
- restricted medial glide
Lateral tilt -difficult to palapate lateral border
-high medial border
-increases with passive medial glide
Posterior tilt -inferior pole displaced posteriorly,
-difficult to palpate due to
infrapatellar fat pad
Rotation -long axis of the patella is not
parellal with long axis of femur
Patella alta - high riding patella24-feb-13Priyanka Urkurkar
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Soft tissue contribution
Soft tissue contribution structural observation
Tight lateral structures lateral displacement or tilt
Compliant medial structures lateral displacement or tilt
Vasti neuromuscular control
Vasti neuromuscular control structural observation
Reduced quads activity reduced ms. Bulk of quads
Delayed onset of VMO reduced ms. bulk of VMO
relative to VL
Reduced magnitude of VMO reduced ms, bulk of VMO
Relative to VL
Altered reflex response reduced ms. bulk of VMO24-feb-13Priyanka Urkurkar
Knee health follows a neat algebraic equation:
feet + hips = knees.
It just so happens that athleticism’s algebraic equation
goes like this:
feet + hips = athleticism.
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Anatomy patellofemoral joint
Biomechanics of patellofemoral joint
Patellofemoral pain syndrome
summary
Priyanka Urkurkar
Poor Control
of Hip
Rotation
Tight Muscles
(e.g. iliotibial
band)
Femoral
Anteversion
Tibial Torsion
Excessive
Pronation
Post-
Surgery
Post knee
injury
Post
patellar
subluxatio
n
Primary
dysfunction Secondary dysfunction
Vastus medialis
obliques dysfunction
Abnormal
Biomechanics
Tight lateral
structures (e.g.
iliotibial band, lateral
retinaculum)
Abnormal Patellar
Tracking Distance running
steps/stains
squats Excessive pressure on
patellofemoral joint
Patellofemoral
syndrome
Increased Q angle
Patella alta
summary
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references
Brukner P, Khan K. Clinical Sports
Medicine. 3rd Edition.
Zuluaga M, Briggs C et al. Sports
Physiotherapy: Applied Science and
Practice.
Levangie PK, Norkin CC. Joint Structure
and Function: A Comprehensive Analysis
Kapandji IA. The physiology of the joints:
Lower extremity
Neumann DA. Kinesiology of the
musculoskeletal system: foundations for
physical rehabilitation24-feb-
13
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