Chapter 7
The
Patellofemoral
Articulation
Introduction
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
Separated from the knee chapter because of
differences in the mechanisms and onset of
injury
Injury is usually due to overuse, congenital
malalignment, or structural insufficiency
Clinical Anatomy
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Patella is largest sesamoid bone in body
Anatomical design allows for:
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Increased efficiency of quadriceps muscle group
Protection of anterior portion of knee joint
Absorption and transmission of patellofemoral
joint reaction forces (forces transmitted through
articular surfaces)
Shape of patella
–
Figure 7-1, page 244
Clinical Anatomy
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Articular surface of patella
– Figure 7-2, page 244
Patella tracks medially during range of 45o to 18o
as knee moves from flexion to extension
During final 18o of extension, patella tracks
laterally
During flexion and extension – patella tracks within
femoral trochlear groove (between the 2 femoral
condyles lined with articular cartilage)
Clinical Anatomy
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Articulation of patellofemoral joint
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Compressive forces
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Table 7-1, page 245
Walking: .5 times body weight
Walking up/down stairs or running hills: 3.3 times
body weight
Lateral retinaculum
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From vastus lateralis and IT band to lateral border
Clinical Anatomy
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Medial retinaculum
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Vastus medialis and adductor magnus to medial
border
Medial and lateral patellofemoral ligaments
–
Superior portion on fibrous capsule thickens and
inserts on patella’s superior border
Muscular Anatomy and Related Soft
Tissue
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Quadriceps muscles
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–
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Flexion – patella is pulled inferiorly by patella
tendon’s attachment to tibial tuberosity
Extension – quadriceps femoris and its tendon
pull patella superiorly
Length of patella is approximately same
length as the long axis of the patella
–
Figure 7-4, page 245
Muscular Anatomy and Related Soft
Tissue
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Vastus lateralis – pulls patella laterally
Vastus medialis (VMO) – guides patella
medially and prevents lateral patellar
subluxation
Tight IT band can accentuate the lateral
tracking of patella, resulting in subluxations
or patellar malalignment
Muscular Anatomy and Related Soft
Tissue

Alignment of foot and normal flexibility of
triceps surae and hamstring muscles are
needed for adequate knee ROM and normal
patellofemoral mechanics
–
Example: increased foot pronation = increased
internal tibial rotation = rotation of tibial tuberosity
toward midline
Bursa of the Extensor Mechanism
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Varying numbers of bursa being directly
involved with extensor mechanism
4 found consistently in population:
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Suprapatellar bursa
Prepatellar bursa
Subcutaneous infrapatellar bursa
Deep infrapatellar bursa
Figure 7-5, page 246
Clinical Evaluation of the
Patellofemoral Articulation
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Dysfunction of joints superior to or inferior to
knee may manifest themselves as
patellofemoral pain
Patient preparedness
Clinician preparedness
History
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Mechanism and onset of injury
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Acute vs. chronic or insidious onset
Chondromalacia Patella
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Softening and wearing away of patella’s hyaline
cartilage; grinding
Box 7-1, page 247
Clarke’s sign - Box 7-5, page 253
When pain occurs
Location of pain
History
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Level of activity
Prior surgery
Relevant past history
Inspection
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Patella alignment
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Patellar alignment
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–
Patellar malalignment
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Figure 7-6, page 247
Box 7-2, page 248
Figure 7-7, page 247
Posture of knee
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Genu varum, valgum, recurvatum
Inspection
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Q angle
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Tubercle sulcus angle
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Relationship between line of pull of quadriceps and the
patellar tendon
Box 7-3, page 250
Box 7-4, page 251
Relationship between tibial tuberosity and inferior patellar
pole
Leg length difference
Foot posture
Areas of scars
Palpation
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
Refer to clinical proficiencies
Utilize pages 249 – 253
Range of Motion Testing
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AROM
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Flexion to extension = patella glides superiorly
and somewhat laterally
Tightness of lateral structures may accentuate
lateral displacement
Flexion = patella glides inferiorly and medially
RROM
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Pain during movement may indicate malalignment
Open and closed kinetic chain
Range of Motion Testing
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Lower extremity flexibility
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Quadriceps, hamstrings, IT band, triceps surae
Tightness may:
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Result in decreased functional ROM
Force the quadriceps to exert more pressure on patella
Cause patellar tracking deficits
Ligamentous Testing
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Evaluate knee ligaments
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Laxity in knee joint can result in abnormal patellar
tracking, secondary to uniplanar or rotatory
shifting of tibia or femur, causing patellofemoral
pain
Ligamentous and capsular stability of patella
is based on presence of patellar tilt and
amount of glide available to patella
Ligamentous Testing
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Patellar Glide
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–
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Patellar Tilt
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Figure 7-9, page 254
Box 7-6, page 255
Box 7-7, page 256
Synthesis of Findings
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Relationship between patellar glide and tilt
Neurologic Testing
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Same as described in Chapter 6
Pathologies and Related Special Tests
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“patellofemoral dysfunction” and “patellofemoral
pain syndrome” used to describe wide range of
symptoms
Onset may occur during inactivity (theater knee)
and/or during or after activity
Differentiation between meniscal and patellar pain
– Table 7-2, page 257
Evaluation Map – page 257
Patellofemoral Pain Syndrome
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All-inclusive diagnosis for pain in and around
the joint that cannot be explained by a
specific pathology
Signs and symptoms
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Insidious onset; occasionally caused by trauma
Primary complaint of anterior knee pain caused
by activity, pain may be constant
Stair climbing, sitting for long periods
swelling
Patellofemoral Pain Syndrome
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Signs and symptoms continued
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Pain increased with AROM and RROM
Surrounding tissues evaluate for tightness and
hyperlaxity by assessing patellar glide and tilt
Assess subtalar joint
Treatment
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Modify activity, NSAIDs, ice, patellar mobilization and
passive stretching, flexibility and strength training
Orthotics, patellar taping
Patellar Maltracking
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Normal tracking depends on relationships
between:
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Alignment of femur on tibia
Q angle
Integrity of soft tissue restraints
Foot mechanics
Flexibility of triceps surae, quads, hamstrings, IT
band
Table 7-3, page 258
Patellar Maltracking
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Predisposing factors:
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Congenital dysfunction
Injury to patella or knee
Increased body weight
Gait mechanics
Gradual onset of symptoms
Redistribution of forces along patellar facets
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Pain during ADLs
Patellar Subluxation and Dislocation
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Acute, chronic, or congenital laxity of medial patellar
restraints or abnormal tightness of lateral
retinaculum results in increased lateral glide of
patella
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Predisposes patient to subluxation or dislocation
Subluxations can occur without patient knowing it
Dislocations shift patella laterally and lock out of
place, obvious deformity and quadriceps spasm
–
Figure 7-10, page 259
Patellar Subluxation and Dislocation
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Most apt to dislocate or subluxate within 20
to 30 degrees of knee flexion or after valgus
blow to knee
May result in fractured patella, osteochondral
damage, bone bruises, osteochondritis
dissecans
Multiple incidences result in wearing of
articular cartilage
Patellar Subluxation and Dislocation
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Predisposing factors
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Hypomobile medial glide
Flattened posterior articulating surface
External tibial rotation and hyperpronated feet
increase Q angle
Family history
Patellar Subluxation and Dislocation
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Evaluative Findings
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Apprehension Test
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Table 7-4, page 260
Box 7-8, page 261
Radiographic examination
Rule out MCL sprain
Treatment
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Conservative vs. surgical
Patellar Tendinitis
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Insidious onset
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Acute onset
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Jumping activities, running sports, weight lifting
Blow to tendon
Repetitive motions on a biomechanically
malaligned extensor mechanism can result in
unequal loads on the extensor mechanism
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Microtearing of fibers
Patellar Tendinitis
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Most common site of pain = inferior pole
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Evaluative Findings
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Pain at superior pole = quadriceps tendinitis
(jumpers knee)
Table 7-5, page 262
MRI may be useful
Conservative vs. surgical treatment
Patellar Tendon Rupture
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Predisposing factors
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Rheumatoid arthritis, diabetes, lupus, chronic
renal disease, gout
Chronic inflammation of tendon
Corticosteroid medications
Tension developed within quadriceps unit
overloads the patellar tendon, resulting in
rupture in midsubstance or avulsion from
patella or patellar tuberosity
Patellar Tendon Rupture
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Evaluative Findings
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Table 7-6, page 262
No ligamentous stability tests should be
performed until examined by physician
Treatment
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Immediate immobilization and transport
Surgical intervention within 7 to 10 days
Rehabilitation to restore knee function; full return
to activity in 12 months
Patellar Bursitis
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Bursa inflamed secondary to:
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Evaluative Findings
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Single traumatic blow
Repeated low-intensity blows
Overuse
Infection (redness, warmth, refer to physician)
Table 7-7, page 264
Figure 7-11, page 263
Treatment – modify activity & control inflammation
Synovial Plica
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Fold of the fibrous membrane that projects
into joint cavity
During maturation, folds are absorbed into
capsule; however, in majority of population, a
thickened area or crease remains
Remains asymptomatic until area is
traumatized
Most commonly affects medial joint capsule
Synovial Plica
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
When symptomatic, plica loses elastic properties
and alters biomechanics of patellar gliding
mechanism
Evaluative Findings
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Test for medial plica syndrome
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Table 7-8, page 264
Box 7-9, page 265
Stutter Test
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Box 7-10, page 266
Synovial Plica
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Confirmed through MRI
Treatment
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Modify activity
Control inflammatory response
Strengthen VMO to lessen symptoms by reducing
tensile forces placed on plica
Osgood-Schlatter Disease
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
Adolescent inflammatory condition that
strikes the tibial tuberosity’s growth plate
where patellar tendon attached
Onset due to repeated avulsion fractures of
tendon from its attachment; caused by rapid
growth and/or increased quad strength
–
Results in osteochondritis of tubercle
Osgood-Schlatter Disease
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Evaluative Findings
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Table 7-9, page 267
Figure 7-12 page 266
Conservative treatment by reducing activity,
controlling inflammation
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Surgical intervention if conservative treatment
fails
Sinding-Larsen-Johansson Disease
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Found at attachment of tendon into inferior
patellar pole (or quad tendon at proximal
pole)
Caused by stress fracture or avulsion
because of repetitive forces associated with
running and jumping
Affects males more often, ages 10-14 yrs
Sinding-Larsen-Johansson Disease
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Evaluative Findings
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Treatment
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Table 7-10, page 268
Rest, immobilization
Decrease inflammation
Modalities, NSAIDs
Stretching and strengthening
May be symptomatic until maturation
Patellar Fracture
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Blunt trauma
May rupture of bursa; palpation reveals
crepitus or false joint
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Figure 7-13, page 268
Active knee extension and passive knee
flexion produce severe pain
Resisted knee extension cannot be
performed due to pain
On-Field Evaluation of Patellofemoral
Injuries
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Equipment considerations
On-field History
On-field Palpation
On-field Functional Tests
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Willingness to move the involved limb
Willingness to bear weight
Initial Management of On-Field Injuries
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Patellar Tendon Rupture
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Gross deformity, immediate loss of function
Splint in extension and transport
Patellar Dislocation
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Obvious deformity
Reduction should not be attempted; spontaneous reduction
may occur
Splint in position if not reduced, in extension if reduced;
transport
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Figure 7-14, page 270