Chapter 20
Extended Lecture Outline

Anatomy of the Knee
o Bones
 Knee joint consists of the femur, tibia, fibula and patella
 Patella is largest sesamoid bone in the human body
 Patella located in the tendon of quadriceps femoris, is divided into three medial facets
and a lateral facet that articulate with the femur
 Patellar tracking depends upon the pull of the quadriceps muscle and patellar tendon, the
depth of the trochlear groove and the shape of the patella
o Articulations
 Knee joint consists of four articulations between the femur and tibia, femur and patella,
femur and fibula and the tibia and fibula
o Menisci
 Medial Meniscus
 C-shaped fibrocartilage, circumference attached firmly to the medial articular
facet of the tibia and to the joint capsule by coronary ligaments
 Attached posteriorly to semimembranosus muscle
 Helps to stabilize the knee, when the knee is flexed at 90 degrees
 Lateral Meniscus
 O-shaped attached to the lateral articular facet on the superior aspect of the tibia
 Also attached loosely to the lateral articular capsule and the popliteal tendon
 Meniscal Blood Supply
 Blood supplied by the medial genicular artery
 Divided into the red-red zone (good blood supply on outer one-third), red-white
zone (middle one-third minimal blood supply), and the white-white zone (inner
one-third is avascular)
o Stabilizing Ligaments
 Anterior Cruciate Ligament
 Prevents the femur from moving posteriorly during weight bearing, and limits
anterior translation of the tibia in non-weight bearing
 Stabilizes the tibia against excessive internal rotation, stabilizes knee in full
extension and prevents hyperextension
 Secondary restraint for valgus or varus stress
 Knee fully extended, posterolateral section is tight, in flexion the posterolateral
fibers loosen and anteromedial fibers tighten
 Works in conjunction with the hamstring group to stabilize the knee joint
 Posterior Cruciate Ligament
 Some portion of PCL is taut throughout the full range of motion
 Prevents hyperextension of the knee, limits anterior translation of the femur
during weight bearing and limits posterior translation of the tibia in non-weight
bearing
 Resists internal rotation of the tibia
 Medial Collateral Ligament
 Attaches above the joint line on the medial epicondyle of the femur and below
on the tibia, just beneath attachment of pes anserine
 Prevents the knee from valgus and external rotatory forces
 Deep Medial Capsular Ligaments
 Divided into three parts: anterior, medial and posterior capsular ligaments
 Anterior capsular ligament connects to the extensor mechanism and the medial
meniscus through the coronary ligaments
 Relaxed during knee extension and tightens in knee flexion


Purpose to attach the medial meniscus to the femur and to allow the tibia to
move on the meniscus inferiorly
 Lateral Collateral Ligament and Related Structures
 Taut during knee extension but relaxed during flexion
 Attached to the lateral epicondyle of the femur and to the head of the fibula
 Arcuate Ligament formed by thickening of posterior capsule, attaches to the
fascia of the popliteal muscle and the posterior horn of the lateral meniscus
 Popliteus muscle stabilizes the knee during flexion and protects the lateral
meniscus pulling it posteriorly
 IT band, popliteus muscle and biceps femoris also help to stabilize the knee
laterally
o Joint Capsule
 Articular surfaces of the knee joint enveloped by the largest joint capsule in the body
 Divided into four regions: Posterolateral, posteromedial, anterolateral and anteromedial
 Posterolateral corner reinforced by the IT band, the popliteus, the biceps femoris, the
LCL and the arcuate ligament
 Posteromedial corner reinforced by MCL, pes anserine tendons, semimembranosus and
posterior oblique ligament
 Anterolateral corner reinforced by IT Band, patellar tendon, and lateral patellar
retinaculum
 Anteromedial corner reinforced by superficial MCL, and medial patellar retinaculum
 Synovial membrane lines the inner surface of the joint capsule, except posteriorly where
it passes in front of the cruciates, making them extrasynovial
o Knee Musculature
 Knee flexion: biceps femoris, semitendinosus, semimembranosus, gracilis, sartorius,
gastrocnemius, popliteus and plantaris
 Knee Extension: Vastus medialis, vastus lateralis, vastus intermedius, rectus femoris
 External Rotation of tibia: Biceps femoris
 Internal Rotation: Popliteus, semitendinosus, semimembranosus, sartorius and gracilis
 IT Band functions as a dynamic lateral stabilizer
o Bursae
 Composed of pieces of synovial tissue which is separated by a thin film of fluid
 Function is to reduce friction between anatomical structures
 Most common around the knee joint: suprapatellar, prepatellar, infrapatellar, pretibial and
gastrocnemius bursae
o Fat Pads
 Infrapatellar fat pad is the largest
 Cushions the front of the knee and separates the patellar tendon from the joint capsule
o Nerve Supply
 Tibial nerve innervates most of the hamstrings and gastrocnemius
 Common peroneal nerve innervates the short head of the biceps femoris
 Peroneal nerve exposed at the head of the fibula
 Femoral nerve innervates the quadriceps and Sartorius
o Blood Supply
 Main blood supply to the knee is from the popliteal artery which stems from the femoral
artery
 From the popliteal artery: four branches supply the knee – medial and lateral superior
genicular, and medial and lateral inferior genicular arteries
 Blood drains via the small saphenous vein into the popliteal vein to the femoral vein
Functional Anatomy
 Movement between tibia and femur involves physiological motions of flexion, extension
and rotation and arthrokinematics motions of rolling, and gliding
 As tibia extends on the femur – tibia glides and rolls anteriorly
 Femur extending on tibia – gliding occurs in anterior direction and rolling occurs
posteriorly


Screw home mechanism: as the knee extends the tibia externally rotates, rotation occurs
due to the medial femoral condyle is larger than the lateral condyle
 During last 15 degrees of extension, the tibia externally rotates and the ACL unwinds
 In complete flexion (140 degrees) knee range is limited by the shortened position and
bulk of the hamstring muscles, and the extensibility of the quadriceps
 Patella aids knee during extension by lengthening the lever arm of the quadriceps,
distributes compressive stresses on the femur by increasing contact area between the
patellar tendon and femur and protects the patellar tendon against friction
 During full extension – patella lies slightly lateral and proximal to trochlea
 At 20 degrees of knee flexion – patella moves into the trochlea due to tibial
rotation
 At 30 degrees – patella is most prominent and moves deeper into the trochlea
 At 90 degrees – patella again becomes positioned laterally
 At 135 degrees the patella moves laterally beyond the trochlea
o The Knee in the Kinetic Chain
 Knee is part of the kinetic chain (Chapter 16)
 Directly affected by motions and forces occurring to and being transmitted from the foot,
ankle and lower leg
 Knee transmits forces to the thigh, hip, pelvis and spine
Assessing the Knee Joint
o History (current and recurrent or chronic injury)
o Observation
 Walking
 Leg Alignment (genu varum (bowlegs), genu valgum (knock-knees), patellar position,
genu recurvatum (hyperextended knees)
 Patellar Malalignment
 Patella Alta (patella sits higher than normal) – length of patellar tendon is 20%
greater than the height of the patella
 Patella Baja (patella sits lower than normal) – ratio of patellar tendon length to
the height of the patella is less than the normal 1:1 ratio
 Measuring for tibial torsion, femoral anteversion and femoral anteversion
 Patellar Orientation
 Position of the patella in relation to the tibia
 Glide: Assesses whether patella is deviated either lateral or medial to the center
of the trochlear groove
 Tilt: Comparing the height of the medial patellar border with the lateral patellar
border
 Rotation: Assesses the deviation of the longitudinal axis (line drawn from the
superior pole to the inferior pole) of the patella in relation to the femur
 Anteroposterior Tilt: Assessed laterally to determine if a line drawn from the
inferior pole to the superior pole is parallel to the long axis of the femur
 Knee symmetry or Asymmetry
 Leg-Length Discrepancy (Chapter 21)
o Palpation
 Bony
 Soft-tissue
 Swelling Patterns
 Intracapsular – Inside the joint capsule (joint effusion)
 Hemarthrosis: Swelling caused by synovial fluid and blood in the joint
 Tests for Effusion (sweep maneuver and ballotable patella)
 Extracapsular – Outside the joint capsule (bursitis, tendonitis, or injury to one of
the collateral ligaments – will localize to the area)
o Special Tests for Assessment of Knee Joint Instability (Table 20-2)
 Determination of the degree of instability
o
o
o
Grade 1 Sprain: Endpoint is firm with little or no instability, some pain
is indicated with testing
o Grade 2 Sprain: Endpoint will be soft with some instability present and
a moderate amount of pain
o Grade 3 Sprain: Complete rupture, endpoint will be very soft with
marked instability, pain will be severe initially, then mild.
 Classification of Knee Joint Instabilities
 Straight instability implies laxity in a single direction, either medial, lateral,
anterior or posterior
 Rotatory instability refer to excessive rotation of the tibial plateau relative to the
femoral condyles (anterolateral, anteromedial, posterolateral, posteromedial
rotatory instability is rarely seen
 Tibial translation: the amount of gliding of the medial tibial plateau as compared
with the lateral tibial plateau relative to the femoral condyles.
 Collateral Ligament Tests
 Valgus and Varus Stress Tests at 0 and 30 degrees
 Apley Distraction Test
 Anterior Cruciate Ligament Tests
 Drawer Test at 90 degrees of Flexion
 Lachman Drawer Test
 Pivot Shift Test
 Jerk Test
 Flexion-Rotation Drawer Test
 Posterior Cruciate Ligament Tests
 Posterior Drawer Test
 External Rotation Recurvatum Test
 Posterior Sag Test (Godfrey’s 90/90 Test)
 Instrument Assessment of Cruciate Laxity
 KT-2000 knee arthrometer, the Stryker knee laxity tester and the Genucom are
three such testing devices
 Provide objective measurements throughout the rehab process
 Meniscal Tests
 McMurray’s Meniscal Test
 Apley Compression Test
 Thessaly Test
 Girth Measurements
 Five sites have been recommended: the joint line (tibial plateau), 8-10 cm above
the joint line, the level of the tibial tubercle, the belly of the gastrocnemius
muscle (measured in cm from the tibial tubercle, and 2 cm above the superior
border of the patella
 Subjective Rating Scales
 Lysholm Knee Scoring Scale (Focus Box 20-1), the Cincinnati Knee Scale, The
International Knee Documentation Committee (IKDC) Scale, and the Knee
Outcome Survey
 Patients perception on how well injured knee is doing relative to pain, stability
and functional performance
Functional Examination
 Observe athlete walking, running, turning, performing figure-eights, backing up, and
stopping.
 Use of the co-contraction test, vertical jump and single-leg hop tests are also useful
 Deep knee bends and duck walks – may help to rule out meniscal pathology
 Resistive strength of the hamstrings and quadriceps
Patellar Examinations
 Measure the Q Angle: (normal is 10 degrees for males and 15 degrees for females)




Measure the A Angle: patellar orientation to the tibial tubercle, an A angle greater than
35 degrees correlated with patellofemoral pathomechanics
 Palpation of the Patella
 Patellar Compression, Patellar Grinding and Apprehension Tests
Prevention of Knee Injuries
o Physical Conditioning and Rehabilitation
 Muscles surrounding the knee joint must be strong and flexible (strength ratios:
hamstrings should have 60-70% of the strength of the quadriceps
o Describing the Risk ACL Injury
 Consists of instructional training techniques
 Proprioceptive balance activities in preseason, have been shown to reduce incidence of
ACL injuries
 Program involving combination of weight training, landing instructional cues, stretching
and plyometric training may potentially reduce the incidence of ACL injuries (soft
landing, load hips, quiet sound and toe-to-heel)
o Shoe Type
 Change from long conical cleats to a large number of short broad cleats has significantly
reduced knee injuries in football
o Functional and Prophylactic Knee Braces
 Discussed in Chapter 7
 The effectiveness of protective knee braces is controversial
 Generally accepted that they have little or no effect on functional performance measures
Recognition and Management of Specific Injuries
o Ligament Injuries
 Medial Collateral Ligament Sprain (Grade I, Grade II and Grade III)
 Lateral Collateral Ligament Sprain
 Anterior Cruciate Ligament Sprain
 Posterior Cruciate Ligament Sprain
o Meniscal Lesions
o Joint Injuries
 Knee Plica
 Osteochondral Knee Fractures
 Osteochondritis Dissecans
 Loose Bodies within the Knee
 Joint Contusions
 Peroneal Nerve Contusion
 Bursitis
o Patellar Conditions
 Patellar fracture
 Acute Patellar Subluxation/Dislocation
 Injury to Infrapatellar Fat Pad
o Patellofemoral Pain Syndrome
 Chondromalacia Patella
 Patellofemoral Stress Syndrome
o Extensor Mechanism Injuries
 Osgood-Schlatter Disease and Larsen-Johansson Disease
 Patellar Tendinitis (Jumpers or Kickers Knee)
 Patellar Tendon Rupture
 Runner’s Knee (Cyclist’s Knee)
Knee Joint Rehabilitation
o General Body Conditioning
 Maintain CV conditioning through non-weight bearing activities (upper-body ergometer,
aquatic exercise, and if ROM permits stationary cycling)
o Weight Bearing
 Best to go on crutches non-weight bearing for 1-2 days after initial injury
 Gradually progress to weight bearing, possibly with athlete wearing a rehabilitative brace

o
o
o
o
o
o
o
Injured structures in the knee joint will not heal fully until they are subjected to normal
tensile forces and strains
Knee Joint Mobilization
 Mobilization techniques should be incorporated early to reduce the arthrofibrosis that
normally occurs with immobilization
 Patellar mobility is the key to regaining normal knee motion
Flexibility
 Regaining full range of motion after knee injury is one of most critical aspects of
rehabilitation
 Range of motion exercises should be initiated on the first day after injury or surgical
intervention
Muscular Strength
 Follows progression from isometric exercises (Quad sets, SLRs) to isotonic exercise, to
isokinetic exercise, to plyometric exercise
 Strengthen all the muscle groups acting on the knee joint (quads, hamstrings, abductors,
adductors and gastrocnemius)
 Emphasize closed kinetic chain exercises as they are more functional and eliminate many
of the stress and shear forces associated with open chain exercises (minisquats, step-ups,
leg presses)
Neuromuscular Control
 Loss of neuromuscular control usually occurs due to pain inhibition or swelling
 Begin with weight shifting activities after initial injury or surgery, SLR’s and quad sets
Bracing
 Rehabilitative braces have been designed to allow protected motion- depending upon the
specific injury or surgical technique, the knee must be protected in limited ranges for
some period of time
 Braces are removed during rehab sessions to allow athlete to work through
ROM
 Rehabilitative braces typically worn for 3-6 weeks after surgery
 Functional Knee Braces are worn to provide support to the unstable knee on return to
activity
 All functional braces are custom-fitted to some degree
 Designed to improve stability of ACL-deficient knee by preventing full
extension
 Functional braces alone do not seem to be able to control pathological laxity
associated with ACL deficiency - also need an appropriate rehab program
 These braces have been shown to restrict anterior-posterior translation of the
tibia at low load
 Functional Resistance Braces have been designed for use in individuals who have
patellofemoral pain syndrome
 Brace provides variable resistance to knee flexion that can be adjusted to
provide progressive increasing resistance
 Worn both during rehab and during ADLs
Functional Progression
 Sport specific skills should be broken down into component parts and practiced
 Gradual return to running is essential
Return to Activity
 Based on several criteria
 Healing process has been given a sufficient amount of time to repair the injured
structure
 Objective criteria include isokinetic evaluation (torque values at least 90% of the
uninjured extremity), arthrometer measurement, and functional performance
tests (single leg hop, hop for distance, figure-eights at increased speed, carioca
etc.)