patellofemoral pain syndrome (pfps)

By- Priyanka Urkurkar

PATHOMECHANICS OF PATELLOFEMORAL

PAIN SYNDROME (PFPS)

24-feb-13Priyanka Urkurkar

contents

PATELLOFEMORAL

ANATOMY

BIOMECHANICS

JOINT PAIN

PATHOMECHANICS

Anatomy of patellofemoral joint Patella is the flat triangularly

shaped largest sesamoid bone

in the body

• It is embedded within the

quadriceps muscles

Posterior articular surface

Medial facet lateral facet odd facet

Divided by a vertical

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

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

Biomechanics of Patellofemoral joint

Motion of the patella

Flexion and extension

Medial and lateral patellar tilt

Medial and lateral rotation of the patella

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

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

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

Longitudinal stabilizers

Quadriceps tendon

Patellar tendon

Patello – tibial ligament

capsule

It provides medial lateral stability of patella in

knee flexion

24-feb-13

Patellar

tendon

Quadrice

tendon

Articular

capsule

Priyanka Urkurkar

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

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)

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

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.

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.

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.

The direction of quadriceps

force produces a measure

known as Q – angle

Increases with femoral

anteversion and/ or external

tibial torsion

The Q - angle

Q – angle for male and female

•The average angle is

• 15.8 ± 4.5 for females

•11.2 ± 3.0 for men

Above 15 degrees is considered excessive in men

Above 17 degrees is considered excessive in

females

This is indicative of severe patellar malalignment.

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

patellofemoral pain syndrome

Usually young ( adolescents) and active

Young athletes

Pain on sitting (movie-goer sign)

Middle aged Female > Male (2.2 times)

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

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.

Extrinsic load is created by ground reaction forces

Is moderated by –

Body mass

Speed of gait

Surfaces

foot wear

Intrinsic load is conceptualized as patella tracking

Factors influence patella tracking

Remote

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

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

Contributes to poor tracking of the patella

Allows vastus lateralis to pull the patella laterally

VMO weakness

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:

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

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

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.

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

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.

24-feb-13

Anatomy patellofemoral joint

Biomechanics of patellofemoral joint

Patellofemoral pain syndrome

summary

Priyanka Urkurkar

Poor Control

of Hip

Rotation

Tight Muscles

(e.g. iliotibial

Femoral

Anteversion

Tibial Torsion

Excessive

Pronation

Surgery

Post knee

injury

patellar

subluxatio

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

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-

Priyanka Urkurkar

patellofemoral pain syndrome (pfps)

patella baja

patella alta

area of contact

vertical position of

high position of patella

surface contact area

area of patellofemoral

femoral sulcus

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