Chapter 20: The Knee and
Related Structures
• Complex joint that endures great amounts
of trauma due to extreme amounts of stress
that are regularly applied
• Hinge joint w/ a rotational component
• Stability is due primarily to ligaments, joint
capsule and muscles surrounding the joint
• Designed for stability w/ weight bearing
and mobility in locomotion
Functional Anatomy
• Movement of the knee requires flexion,
extension, rotation and the arthrokinematic
motions of rolling and gliding
• Rotational component involves the “screw
home mechanism”
– As the knee extends it externally rotates
because the medial femoral condyle is larger
than the lateral
– Provides increased stability to the knee
– Popliteus “unlocks” knee allowing knee to flex
• Capsular ligaments are taut during full
extension and relaxed w/ flexion
– Allows rotation to occur
– Deeper capsular ligaments remain taut to keep
rotation in check
• PCL prevents excessive internal rotation,
guides the knee in flexion, and acts as drag
during initial glide phase of flexion
• ACL stops excessive internal rotation,
stabilizes the knee in full extension and
prevents hyperextension
• Range of motion includes 140 degrees of
motion
– Limited by shortened position of hamstrings,
bulk of hamstrings and extensibility of quads
• Patella aids knee during extension,
providing a mechanical advantage
– Distributes compressive stress on the femur by
increasing contact between patellar tendon and
femur
– Protects patellar tendon against friction
– When moving from extension to flexion the
patella glides laterally and further into trochlear
groove
• Kinetic Chain
– Directly affected by motions and forces
occurring at the foot, ankle, lower leg, thigh,
hip, pelvis, and spine
– With the kinetic chain forces must be absorbed
and distributed
– If body is unable to manage forces, breakdown
to the system occurs
– Knee is very susceptible to injury resulting
from absorption of forces
Assessing the Knee Joint
• Determining the mechanism of injury is
critical
• History- Current Injury
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Past history
Mechanism- what position was your body in?
Did the knee collapse?
Did you hear or feel anything?
Could you move your knee immediately after
injury or was it locked?
– Did swelling occur?
– Where was the pain
• History - Recurrent or Chronic Injury
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What is your major complaint?
When did you first notice the condition?
Is there recurrent swelling?
Does the knee lock or catch?
Is there severe pain?
Grinding or grating?
Does it ever feel like giving way?
What does it feel like when ascending and
descending stairs?
– What past treatment have you undergone?
• Observation
– Walking, half squatting, going up and down
stairs
– Swelling, ecchymosis,
– Leg alignment
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Genu valgum and genu varum
Hyperextension and hyperflexion
Patella alta and baja
Patella rotated inward or outward
– May cause a combination of problems
• Tibial torsion, femoral anteversion and retroversion
• Tibial torsion
– An angle that measures
less than 15 degrees is an
indication of tibial torsion
• Femoral Anteversion
and Retroversion
– Total rotation of the hip
equals ~100 degrees
– If the hip rotates >70
degrees internally,
anteversion of the hip
may exist
– INSERT 20-9
– Knee Symmetry or Asymmetry
• Do the knees look symmetrical? Is there obvious
swelling? Atrophy?
– Leg Length Discrepancy
• Anatomical or functional
• Anatomical differences can potentially cause
problems in all weight bearing joints
• Functional differences can be caused by pelvic
rotations or mal-alignment of the spine
•Palpation - Bony
• Medial tibial plateau
• Medial femoral
condyle
• Adductor tubercle
• Gerdy’s tubercle
• Lateral tibial plateau
• Lateral femoral
condyle
• Lateral epicondyle
• Head of fibula
• Tibial tuberosity
• Superior and inferior
patella borders (base
and apex)
• Around the periphery
of the knee relaxed, in
full flexion and
extension
•Palpation - Soft Tissue
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Vastus medialis
Vastus lateralis
Vastus intermedius
Rectus femoris
Quadriceps and
patellar tendon
Sartorius
Medial patellar plica
Anterior joint capsule
Iliotibial Band
Arcuate complex
• Medial and lateral
collateral ligaments
• Pes anserine
• Medial/lateral joint
capsule
• Semitendinosus
• Semimembranosus
• Gastrocnemius
• Popliteus
• Biceps Femoris
• Palpation of Swelling
– Intra vs. extracapsular swelling
– Intracapsular may be referred to as joint
effusion
– Swelling w/in the joint that is caused by
synovial fluid and blood is a hemarthrosis
– Sweep maneuver
– Ballotable patella - sign of joint effusion
– Extracapsular swelling tends to localize over
the injured structure
• May ultimately migrate down to foot and ankle
• Special Tests for Knee Instability
– Use endpoint feel to determine stability
– MRI may also be necessary for assessment
– Classification of Joint Instability
• Knee laxity includes both straight and rotary
instability
• Translation (tibial translation) refers to the glide of
tibial plateau relative to the femoral condyles
• As the damage to stabilization structures increases,
laxity and translation also increase
– Valgus and Varus Stress Tests
• Used to assess the integrity of the MCL and LCL
respectively
• Testing at 0 degrees incorporates capsular testing
while testing at 30 degrees of flexion isolates the
ligaments
– Anterior Cruciate Ligament Tests
• Drawer test at 90 degrees of flexion
– Tibia sliding forward from under the femur is considered a
positive sign (ACL)
– Should be performed w/ knee internally and externally to
test integrity of joint capsule
• Lachman Drawer
Test
– Will not force knee
into painful flexion
immediately after
injury
– Reduces hamstring
involvement
– At 30 degrees of
flexion an attempt is
made to translate the
tibia anteriorly on the
femur
– A positive test
indicates damage to
the ACL
• Pivot Shift Test
– Used to determine
anterolateral rotary
instability
– Position starts w/ knee
extended and leg
internally rotated
– The thigh and knee are
then flexed w/ a valgus
stress applied to the knee
– Reduction of the tibial
plateau (producing a
clunk) is a positive sign
– Jerk Test
• Reverses direction of the pivot shift
• Moves from position of flexion to extension
• W/out and ACL the tibia will sublux at 20 degrees
of flexion
– Flexion-Rotation Drawer Test
• Knee is taken from a position of 15 degrees of
flexion (tibia is subluxed anteriorly w/ femur
externally rotated)
• Knee is moved into 30 degrees of flexion where
tibia rotates posteriorly and femur internally rotates
• Posterior Cruciate Ligament Tests
– Posterior Drawer Test
• Knee is flexed at 90 degrees and a posterior force is
applied to determine translation posteriorly
• Positive sign indicates a PCL deficient knee
– External Rotation Recurvatum Test
• With the athlete supine, the leg is lifted by the great
toe
• If the tibia externally rotates and slides posteriorly
there may be a PCL injury and damage to the
posterolateral corner of the capsule
• Posterior Sag
Test (Godfrey’s
test)
– Athlete is
supine w/ both
knees flexed to
90 degrees
– Lateral
observation is
required to
determine extent
of posterior sag
while
comparing
bilaterally
•Instrument Assessment of the Cruciate
Ligaments
• A number of devices
are available to
quantify AP
displacement of the
knee
• KT-2000 arthrometer,
Stryker knee laxity
tester and Genucom
can be used to assess
the knee
• Test can be taken pre
& post-operatively and
through rehab
• Meniscal Tests
– McMurray’s Meniscal Test
• Used to determine displaceable meniscal tear
• Leg is moved into flexion and extension while knee
is internally and externally rotated in conjunction w/
valgus and varus stressing
• A positive test is found w/ clicking and popping
response
• Apley’s Compression
Test
– Hard downward
pressure is applied w/
rotation
– Pain indicates a
meniscal injury
• Apley’s Distraction
Test
– Traction is applied w/
rotation
– Pain will occur if there
is damage to the
capsule or ligaments
– No pain will occur if it
is meniscal
• Girth Measurements
– Changes in girth can occur due to atrophy,
swelling and conditioning
– Must use circumferential measures to determine
deficits and gains during the rehabilitation
process
– Measurements should be taken at the joint line,
the level of the tibial tubercle, belly of the
gastrocnemius, 2 cm above the superior border
of the patella, and 8-10 cm above the joint line
• Subjective Rating
– Used to determine patient’s perception of pain,
stability and functional performance
• Functional Examination
– Must assess walking, running, turning and
cutting
– Co-contraction test, vertical jump, single leg
hop tests and the duck walk
– Resistive strength testing
• Q-Angle
– Lines which bisects the patella relative to the
ASIS and the tibial tubercle
– Normal angle is 10 degrees for males and 15
degrees for females
– Elevated angles often lead to pathological
conditions associated w/ improper patella
tracking
• The A Angle
– Patellar orientation to the tibial tubercle
– Quantitative measure of the patellar
realignment after rehabilitation
– An angle greater than 35 degrees is often
correlated w/ patellofemoral pathomechanics
• Palpation of the Patella
– Must palpate around and under patella to
determine points of pain
• Patella Grinding, Compression and
Apprehension Tests
– A series of glides and compressions are
performed w/ the patella to determine integrity
of patellar cartilage
Prevention of Knee Injuries
• Physical Conditioning and Rehabilitation
– Total body conditioning is required
• Strength, flexibility, cardiovascular and muscular
endurance, agility, speed and balance
– Muscles around joint must be conditioned
(flexibility and strength) to maximize stability
– Must avoid abnormal muscle action through
flexibility
– In an effort to prevent injury, extensibility of
hamstrings, erector spinae, groin, quadriceps
and gastrocnemius is important
• ACL Prevention Programs
– Focus on strength, neuromuscular control,
balance
– Series of different programs which address
balance board training, landing strategies,
plyometric training, and single leg performance
– Can be implemented in rehabilitation and
preventative training programs
• Shoe Type
– Change in football footwear has drastically
reduced the incidence of knee injuries
– Shoes w/ more shorter cleats does not allow
foot to become fixed while still allowing for
control w/ running and cutting
• Functional and
Prophylactic Knee
Braces
– Used to prevent and
reduce severity of knee
injuries
– Used to protect MCL,
or prevent further
damage to grade 1 & 2
sprains of the ACL or
to protect the ACL
following surgery
– Can be custom molded
and designed to control
rotational forces
Recognition and Management of
Specific Injuries
• Medial Collateral Ligament Sprain
– Etiology
• Result of severe blow or outward twist
– Signs and Symptoms - Grade I
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Little fiber tearing or stretching
Stable valgus test
Little or no joint effusion
Some joint stiffness and point tenderness on lateral
aspect
• Relatively normal ROM
– Management
• RICE for at least 24
hours
• Crutches if necessary
• Follow-up care will
include cryokinetics
w/ exercise
• Move from
isometrics and STLR
exercises to bicycle
riding and isokinetics
• Return to play when
all areas have
returned to normal
• May require 3 weeks
to recover
– Signs and Symptoms (Grade II)
• Complete tear of deep capsular ligament and partial tear
of superficial layer of MCL
• No gross instability; laxity at 5-15 degrees of flexion
• Slight swelling
• Moderate to severe joint tightness w/ decreased ROM
• Pain along medial aspect of knee
– Management
• RICE for 48-72 hours; crutch use until acute phase has
resolved
• Possibly a brace or casting prior to the initiation of
ROM activities
• Modalities 2-3 times daily for pain
• Gradual progression from isometrics (quad exercises)
to CKC exercises; functional progression activities
– Signs and Symptoms (Grade III)
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Complete tear of supporting ligaments
Complete loss of medial stability
Minimum to moderate swelling
Immediate pain followed by ache
Loss of motion due to effusion and hamstring
guarding
• Positive valgus stress test
– Management
• RICE
• Conservative non-operative versus surgical
approach
• Limited immobilization (w/ a brace); progressive
weight bearing for
• Rehab would be similar to Grade I & II injuries
• Lateral Collateral Ligament Sprain
– Etiology
• Result of a varus force, generally w/ the tibia
internally rotated
• Direct blow is rare
• If severe enough damage can also occur to the
cruciate ligaments, ITB, and meniscus, producing
bony fragments as well
– Signs and Symptoms
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Pain and tenderness over LCL
Swelling and effusion around the LCL
Joint laxity w/ varus testing
May cause irritation of the peroneal nerve
– Management
• Following management of MCL injuries depending
on severity
• Anterior Cruciate Ligament Sprain
– Etiology
• MOI - tibia externally rotated and valgus force at the
knee (occasionally the result of hyperextension from
direct blow)
• May be linked to inability to decelerate valgus and
rotational stresses - landing strategies
• Male versus female
• Research is quite extensive in regards to impact of
femoral notch, ACL size and laxity, malalignments
(Q-angle) faulty biomechanics
• Extrinsic factors may include, conditioning, skill
acquisition, playing style, equipment, preparation
time
• Also involves damage to other structures including
meniscus, capsule, MCL
– Signs and Symptoms
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Experience pop w/ severe pain and disability
Rapid swelling at the joint line
Positive anterior drawer and Lachman’s
Other ACL tests may also be positive
– Management
• RICE; use of crutches
• Arthroscopy may be necessary to determine extent
of injury
• Could lead to major instability in incidence of high
performance
• W/out surgery joint degeneration may result
• Age and activity may factor into surgical option
• Surgery may involve joint reconstruction w/ grafts
(tendon), transplantation of external structures
– Will require brief hospital stay and 3-5 weeks of a brace
– Also requires 4-6 months of rehab
• Posterior Cruciate Ligament Sprain
– Etiology
• Most at risk during 90 degrees of flexion
• Fall on bent knee is most common mechanism
• Can also be damaged as a result of a rotational force
– Signs and Symptoms
• Feel a pop in the back of the knee
• Tenderness and relatively little swelling in the
popliteal fossa
• Laxity w/ posterior sag test
– Management
• RICE
• Non-operative rehab of grade I and II injuries should
focus on quad strength
• Surgical versus non-operative
– Surgery will require 6 weeks of immobilization in
extension w/ full weight bearing on crutches
– ROM after 6 weeks and PRE at 4 months
• Meniscal Lesions
– Etiology
• Medial meniscus is more commonly injured due to
ligamentous attachments and decreased mobility
– Also more prone to disruption through torsional and
valgus forces
• Most common MOI is rotary force w/ knee flexed or
extended
• Can be longitudinal, oblique or transverse tears
– Signs and Symptoms
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Effusion developing over 48-72 hour period
Joint line pain and loss of motion
Intermittent locking and giving way
Pain w/ squatting
Portions may become detached causing locking,
giving way or catching w/in the joint
• If chronic, recurrent swelling or muscle atrophy may
occur
– Management
• If the knee is not locked, but indications of a tear are
present further diagnostic testing may be required
• If locking occurs, anesthesia may be necessary to
unlock the joint w/ possible arthroscopic surgery
follow-up
• W/ surgery all efforts are made to preserve the
meniscus -- will full healing being dependent on
location
• Menisectomy rehab allows partial weight bearing
and quick return to activity
• Repaired meniscus will require immobilization and
a gradual return to activity over the course of 12
weeks
• Knee Plica
– Etiology
• Irritation of the plica (generally, mediopatellar plica
and often associated w/ chondromalacia
– Signs and Symptoms
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Possible history of knee pain/injury
Recurrent episodes of painful pseudo-locking
Possible snapping and popping
Pain w/ stairs and squatting
Little or no swelling, and no ligamentous laxity
– Management
• Treat conservatively w/ RICE and NSAID’s if the
result of trauma
• Recurrent conditions may require surgery
• Osteochondral Knee Fractures
– Etiology
• Same MOI as collateral/cruciate ligaments or
meniscal injuries
• Twisting, sudden cutting or direct blow
– Signs and Symptoms
• Hear a snap and feeling of giving way
• Immediate swelling and considerable pain
– Management
• Diagnosis confirmed through arthroscopic exam, w/
surgery to replace fragment to avoid joint
degeneration and arthritis
• Osteochondritis Dissecans
– Etiology
• Partial or complete separation of articular cartilage
and subchondral bone
• Cause is unknown but may include blunt trauma,
possible skeletal or endocrine abnormalities,
prominent tibial spine impinging on medial femoral
condyle, or impingement due to patellar facet
– Signs and Symptoms
• Aching pain with recurrent swelling and possible
locking
• Possible quadriceps atrophy and point tenderness
– Management
• Rest and immobilization for children
• Surgery may be necessary in teenagers and adults
(drilling to stimulate healing, pinning or bone grafts
• Loose Bodies w/in the Knee
– Etiology
• Result of repeated trauma
• Possibly stem from osteochondritis dissecans,
meniscal fragments, synovial tissue or cruciate
ligaments
– Signs and Symptoms
• May become lodged, causing locking or popping
• Pain and sensation of instability
– Management
• If not surgically removed it can lead to conditions
causing joint degeneration
• Joint Contusions
– Etiology
• Blow to the muscles crossing the joint (vastus
medialis)
– Signs and Symptoms
• Present as knee sprain, severe pain, loss of
movement and signs of acute inflammation
• Swelling, discoloration
• Possible capsular damage
– Management
• RICE initially and continue if swelling persists
• Gradual progression to normal activity following
return of ROM and padding for protection
• If swelling does not resolve w/in a week a chronic
condition (synovitis or bursitis) may exist requiring
more rest
• Peroneal Nerve Contusion
– Etiology
• Compression of peroneal nerve due to a direct blow
– Signs and Symptoms
• Local pain and possible shooting nerve pain
• Numbness and paresthesia in cutaneous distribution
of the nerve
• Added pressure may exacerbate condition
• Generally resolves quickly -- in the event it does not
resolve, it could result in drop foot
– Management
• RICE and return to play once symptoms resolve and
no weakness is present
• Padding for fibular head is necessary for a few
weeks
• Bursitis
– Etiology
• Acute, chronic or recurrent swelling
• Prepatellar = continued kneeling
• Infrapatellar = overuse of patellar tendon
– Signs and Symptoms
• Prepatellar bursitis may be localized swelling above
knee that is ballotable
• Swelling in popliteal fossa may indicate a Baker’s
cyst
– Associated w/ semimembranosus bursa or medial head of
gastrocnemius
– Commonly painless and causing little disability
– May progress and should be treated accordingly
– Management
• Eliminate cause, RICE and NSAID’s
• Patellar Fracture
– Etiology
• Direct or indirect trauma (severe pull of tendon)
• Forcible contraction, falling, jumping or running
– Signs and Symptoms
• Hemorrhaging and joint effusion w/ generalized
swelling
• Indirect fractures may cause capsular tearing,
separation of bone fragments and possible
quadriceps tendon tearing
• Little bone separation w/ direct injury
– Management
• X-ray necessary for confirmation of findings
• RICE and splinting if fracture suspected
• Refer and immobilize for 2-3 months
• Acute Patella Subluxation or Dislocation
– Etiology
• Deceleration w/ simultaneous cutting in opposite
direction (valgus force at knee)
• Quad pulls the patella out of alignment
• Some athletes may be predisposed to injury
• Repetitive subluxation will impose stress to medial
restraints
– Signs and Symptoms
• W/ subluxation, pain and swelling, restricted ROM,
palpable tenderness over adductor tubercle
• Dislocations result in total loss of function
– Management
• Reduction is performed by flexing hip, moving
patella medially and slowly extending the knee
• Following reduction, immobilization for at least 4
weeks w/ use of crutches and isometric exercises
during this period
• After immobilization period, horseshoe pad w/
elastic wrap should be used to support patella
• Muscle rehab focusing on muscle around the knee,
thigh and hip are key (STLR’s are optimal for the
knee)
• Possible surgery to release tight structures
• Improve postural and biomechanical factors
• Injury to the Infrapatellar Fat Pad
– Etiology
• May become wedged between the tibia and patella
• Irritated by chronic kneeling, pressure or trauma
– Signs and Symptoms
• Capillary hemorrhaging and swelling
• Chronic irritation may lead to scarring and
calcification
• Pain below the patellar ligament (especially during
knee extension)
• May display weakness, mild swelling and stiffness
during movement
– Management
• Rest from irritating activities until inflammation has
subsided and therapeutic use of cold
• Heel lift to prevent irritation during extension
• Hyperextension taping to prevent full extension
• Chondromalacia patella
– Etiology
• Softening and deterioration of the articular cartilage
• Possible abnormal patellar tracking due to genu
valgum, external tibial torsion, foot pronation,
femoral anteversion, patella alta, shallow femoral
groove, increased Q angle, laxity of quad tendon
– Signs and Symptoms
• Pain w/ walking, running, stairs and squatting
• Possible recurrent swelling, grating sensation w/
flexion and extension
• Pain at inferior border during palpation
– Management
• Conservative measures
– RICE, NSAID’s, isometrics, orthotics to correct
dysfunction
• Surgical possibilities
• Patellofemoral Stress Syndrome
– Etiology
• Result of lateral deviation of patella while tracking
in femoral groove
– Tight structures, pronation, increased Q angle, insufficient
medial musculature
– Signs and Symptoms
• Tenderness of lateral facet of patella and swelling
associated w/ irritation of synovium
• Dull ache in center of knee
• Patellar compression will elicit pain and crepitus
• Apprehension when patella is forced laterally
– Management
• Correct imbalances (strength and flexibility)
• McConnell taping
• Lateral retinacular release if conservative measures
fail
• Osgood-Schlatter Disease and LarsenJohansson Disease
– Etiology
• Osgood Schlatter’s is an apophysitis occurring at the
tibial tubercle
– Begins cartilagenous and develops a bony callus, enlarging
the tubercle
– Resolves w/ aging
– Common cause = repeated avulsion of patellar tendon
• Larsen Johansson is the result of excessive pulling on
the inferior pole of the patella
– Signs and Symptoms
• Both elicit swelling, hemorrhaging and gradual
degeneration of the apophysis due to impaired
circulation
– Signs and Symptoms (continued)
• Pain w/ kneeling, jumping and running
• Point tenderness
– Management
• Conservative
– Reduce stressful activity until union occurs (6-12 months)
– Possible casting, ice before and after activity
– Isometerics
• Patellar Tendinitis (Jumper’s or Kicker’s
Knee)
– Etiology
• Jumping or kicking - placing tremendous stress and
strain on patellar or quadriceps tendon
• Sudden or repetitive extension
– Signs and Symptoms
• Pain and tenderness at inferior pole of patella
– 3 phases - 1)pain after activity, 2)pain during and after,
3)pain during and after (possibly prolonged) and may
become constant
– Management
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Ice, phonophoresis, iontophoresis, ultrasound, heat
Exercise
Patellar tendon bracing
Transverse friction massage
• Patellar Tendon Rupture
– Etiology
• Sudden, powerful quad contraction
• Generally does not occur unless a chronic
inflammatory condition persist resulting in tissue
degeneration
• Occur primarily at point of attachment
– Signs and Symptoms
• Palpable defect, lack of knee extension
• Considerable swelling and pain (initially)
– Management
• Surgical repair is needed
• Proper conservative care of jumper’s knee can
minimize chances of occurring
• If steroids are being used, intense knee exercise
should be avoided due to weakening of collagen
• Runner’s Knee (Cyclist’s Knee)
– Etiology
• General expression for repetitive/overuse conditions
attributed to mal-alignment and structural
asymmetries
– Signs and Symptoms
• IT Band Friction Syndrome
– Irritation at band’s insertion - commonly seen in individual
that have genu varum or pronated feet
• Pes Anserine Tendinitis or Bursitis
– Result of excessive genu valgum and weak vastus medialis
– Due to running w/ one leg higher than the other
– Management
• Correction of mal-alignments
• Ice before and after activity, proper warm-up and
stretching
• Avoidance of aggravating activities
• NSAID’s and orthotics
Knee Joint Rehabilitation
• General Body Conditioning
– Must be maintained with non-weight bearing
activities
• Weight Bearing
– Initial crutch use, non-weight bearing
– Gradual progression to weight bearing while
wearing rehabilitative brace
• Knee Joint Mobilization
– Used to reduce arthrofibrosis
– Patellar mobilization is key following surgery
– CPM units
• Flexibility
– Must be regained, maintained and improved
• Muscular Strength
– Progression of isometrics, isotonic training,
isokinetics and plyometrics
– Incorporate eccentric muscle action
– Open versus closed kinetic chain exercises
• Neuromuscular Control
– Loss of control is generally the result of pain
and swelling
– Through exercise and balance equipment
proprioception can be enhanced
• Bracing
– Variety of braces for a variety of injuries and
conditions
– Typically worn for 3-6 weeks after surgery -used to limit ranges for a period of time
– Some are used to control for specific injuries
while others are designed for specific forces
and stability
• Functional Progression
– Gradual return to sports specific skills
– Progress w/ weight bearing, move into walking
and running, and then onto sprinting and
change of direction
• Return to Activity
– Based on healing process - sufficient time for
healing must be allowed
– Objective criteria include strength and ROM
measures as well as functional performance
tests