chapter 15 knee conditions

Copyright © 2011 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 15

Knee Conditions

Chapter 15

Knee Conditions


Knee AnatomyKnee AnatomyStructure of the knee. A. Anterior view. B. Posterior view


Knee Anatomy (cont’d)Knee Anatomy (cont’d)

Structures of the knee. C. Lateral view. D. Medial view


Knee Anatomy (cont’d)Knee Anatomy (cont’d)Structures of the knee. E. Superior surface of the tibia. F. Bursa of the knee



• Tibiofemoral Joint

– Condyles of femur with plateaus of tibia

– Hinge joint—flexion/extension

– Tibia does rotate laterally on femur during last few degrees of extension

– “Screwing-home mechanism”

• Produces a locking of the knee in final degrees during extension



• Meniscus

– Fibrocartilaginous discs attached to tibial plateaus

– Medial and lateral

E. Superior surface of the tibia



• Meniscus (cont’d)

• Functions:

– Stabilize joint by deepening the articulation

– Shock absorption

– Provide lubrication and nourishment

– Improve weight distribution

• Medial meniscus has an attachment to the MCL and semimembranosus


Joint Capsule and BursaeJoint Capsule and Bursae

• Articular capsule – encompasses both tibiofemoral and patellofemoral joints

• Bursa inside the capsule

– Suprapatellar bursa

– Subpopliteal bursa

– Semimembranosus bursa


Joint Capsule and BursaeJoint Capsule and Bursae

• Bursa outside capsule

– Prepatellar bursa

– Superficial infrapatellar bursa

– Deep infrapatellar bursa

F. Bursa at the knee


Ligaments Ligaments

• ACL

– Prevents:

• Anterior translation of tibia on femur

• Rotation of tibia on femur

• Hyperextension

• PCL

– Resists posterior displacement of tibia on femur


Ligaments (cont’d)Ligaments (cont’d)• MCL

– Resist medially directed (valgus) forces

• LCL

– Resist laterally directed (varus) forcesA. Anterior view. B. Posterior view


Patellofemoral JointPatellofemoral Joint

• Patella

– Superior, middle, and inferior articular surfaces

– Functions

• Protect femur

• Increase effective power of quadriceps


Patellofemoral Joint (cont’d)Patellofemoral Joint (cont’d)Patella. A. Anterior view. B. Posterior view


Q-AngleQ-Angle

• Q-angle

– Angle between line of resultant force produced byquadriceps and line of patellar tendon

– Males 13°; females 18°

Q-angle— lateral patellofemoral contact Q-angle— medial tibiofemoral contact


Q-Angle (cont’d)Q-Angle (cont’d)


Nerves Nerves

• Tibial nerve

– Hamstrings except short head of biceps

• Common peroneal

– Short head of biceps

• Femoral

– Quadriceps


Nerves (cont’d)Nerves (cont’d)

Innervation of the knee.A. Anterior view. B. Posterior view


Blood SupplyBlood Supply

• Femoral artery

• Popliteal artery

• Genicular arteries

Collateral circulation around the knee. A. Anterior. B. Posterior. C. Circulation to meniscus


Kinematics and Major Muscle ActionsKinematics and Major Muscle Actions

• Knee flexion

– Hamstrings

– Assisted by:

• Popliteus

• Gastrocnemius

• Gracilis

• Sartorius

Motions at the knee.A. Flexion and extension


Kinematics and Major Muscle Actions (cont’d)


• Knee extension

– Quadriceps femoris muscle group

• Rectus femoris

• Vastus lateralis

• Vastus intermedius

• Vastus medialis

• Vastus medialis oblique (VMO)




• Knee extension (cont’d)

– Screw-home motion

• Rotation and passive abduction and adduction

– Capability maximal at approximately 90° of knee flexion




• Patellofemoral joint motion

– During knee flexion and extension, patella glides in the trochlear groove

– Tracking is dependent on the direction of the net force produced by the attached quadriceps


Prevention of Knee InjuriesPrevention of Knee Injuries

• Physical conditioning

– Strength

– Flexibility

• Rule changes

• Footwear

– Cleats vs. flat sole

– Position of cleats and size


Contusions Contusions • Knee

– MOI: compression

– S&S

• Localized tenderness

• Pain

• Swelling

– Management: standard acute; extreme point tenderness physician referral

– Caution: excessive swelling could mask other injuries


Contusions (cont’d)Contusions (cont’d)

• Infrapatellar fat pad

– Entrapped between the femur and tibia

– S&S

• Locking, catching, giving way

• Palpable pain on either side of patellar tendon

• Extreme pain on forced extension



• Infrapatellar fat pad (cont’d)

– Management

• Standard acute

• If symptoms persist > 2-3 days, physician referral

• Protect the area during activity



• Peroneal nerve

– MOI: blow to the posterolateral aspect of the knee

– S&S

• Radiating pain down lateral aspect of leg and foot



• Peroneal nerve (cont’d)

– S&S (cont’d)

• Severe cases

• Initial pain—not immediately followed by tingling or numbness

• As swelling ↑ within nerve sheath

• Weakness in dorsiflexion or eversion




– S&S (cont’d)

• Severe cases

• As swelling ↑ within nerve sheath

• Loss of sensation in dorsum of foot, especially between 1st and 2nd toes

• May progressively occur days or weeks later




– Management:

• Standard acute, but caution with compression

• Severe S&S—immediate physician referral


Bursitis Bursitis • Prepatellar

– MOI

• Acute: direct blow to anterior patella

• Chronic: repetitive blows

– S&S

• Swelling

• Pain with direct pressure

• Pain with passive knee flexion

• Localized swelling


Bursitis (cont’d)Bursitis (cont’d)

• Pes anserine

– MOI:

• Friction between tendon and MCL

• Direct trauma

– S&S

• Pain with knee flexion



• Infrapatellar

– Mechanism:

• Friction between patellar tendon and fat pad/tibia

• May be associated with patellar tendinitis



• Infrapatellar (cont’d)

– S&S

• Point tender with possible swelling posterior to patellar tendon

pain at end range of resisted knee extension and passive flexion

• Prolonged knee flexion may symptoms



• Bursitis management

– Standard acute; aggravating activities or total rest

– Protect area during activity


Ligamentous ConditionsLigamentous Conditions

• AAOS classifies ligamentous knee injuries according to:

– Functional disruption of a specific ligament

– Amount of laxity

– Direction of laxity

• Direction divides laxity into 4 straight and 4 rotatory laxities

• Knowing knee position at impact and direction the tibia displaces or rotates indicates the damaged structures


Ligamentous Conditions (cont’d)Ligamentous Conditions (cont’d)

Knee instability



• Straight medial laxity (valgus laxity)

– Involves MCL; posterior medial capsule—possibly PCL

– Lateral forces cause tension on medial aspect of knee



• Straight medial laxity (valgus laxity) (cont’d)

– 1st degree

• Mild pain medial joint line

• Little or no joint effusion/mild swelling at site

• Full ROM with minor discomfort

• Valgus @ 0°—stable; @ 30º—+



• Straight medial laxity (valgus laxity) (cont’d)

– 2nd or 3rd degree

• Unable to fully extend the leg; often walk on the ball of foot; unable to keep heel flat on the ground



• Straight lateral laxity (varus laxity)

– Involves LCL, lateral capsular ligaments, PCL

– Medial forces produce tension on lateral aspect of knee

• Not usually isolated—presence of IT band, biceps femoris, popliteus



• Straight lateral laxity (varus laxity) (cont’d)

– S&S

• Similar to MCL

• Swelling minimal—no attachment to capsule

• Instability may not be obvious if other stabilizers are intact



• Straight anterior laxity (anterior instability)

– Anterior displacement of tibia on femur

– Involves ACL—rarely isolated

– MOI: cutting or turning maneuver, landing, or sudden deceleration



• Straight anterior laxity (anterior instability) (cont’d)

– S&S

• Pain

• Minimal and transient to severe and lasting

• Deep in knee difficult to pinpoint

• “Pop”

• Effusion within 3 hours; reports knee giving way—does not feel right



• Straight posterior laxity

– Tibia displaced posteriorly

– Involves PCL

– MOI

• Hyperextension force

• Fall on flexed knee (initial contact at tibial tuberosity)



• Straight posterior laxity (cont’d)

– S&S

• Sense of stretching to posterior knee

• “Pop”

• Rapid joint effusion

• ↓ knee flexion due to effusion



• Management

– Standard acute

– Unable to walk normally – crutches should be used

– Physician referral

• Not typically an ER, but seen by physician 1-2 post-injury


Knee Dislocation/SubluxationKnee Dislocation/Subluxation

• Minimum of 3 ligaments torn for knee to dislocate

– Most often—ACL, PCL, and one collateral ligament

• Concern: damage to other structures; especially neurovascular

• MOI: cutting, twisting, or pivoting maneuver


Knee Dislocation/Subluxation (cont’d)Knee Dislocation/Subluxation (cont’d)

• S&S

– Individual describes severe injury

– “Pop”

– Deformity (unless spontaneously reduced)

• Management: standard acute

– Spontaneous reduction—physician referral

– Not reduced—activate emergency plan, including summoning EMS


Meniscal ConditionsMeniscal Conditions

• Classified according to location

• Involve compression, tension, shearing forces

• Longitudinal

– Twisting motion when foot fixed and knee flexed

• Produces compression and torsion on posterior peripheral attachment

– Bucket-handle tear

• Longitudinal segment displaced medially toward center of tibia


Meniscal Conditions (cont’d)Meniscal Conditions (cont’d)

Meniscal tears



• Horizontal tear

– Due largely to degeneration

– Shearing from rotational forces

• Tears the inner surface of the meniscus

– Parrot-beak tear

• 2 tears; commonly in middle segment of lateral meniscus



Meniscal tears



• S&S

– Initial symptoms may be vague or limited

• Limited sensory nerve supply—minimal pain

• Minimal disability

• Minimal swelling

– Understand mechanism



• S&S (cont’d)

– Delayed swelling

– Joint line pain

– Classic: clicking/locking (not acutely) leads to knee buckling or giving way

• Management

– Standard acute; treat symptoms



Patellar ConditionsPatellar Conditions

• Patellofemoral pain

– Causes

• Mechanical (e.g., patellar subluxation or dislocation)

• Inflammatory (e.g., prepatellar bursitis, patellar tendinitis)

• Other causes (e.g., reflex sympathetic dystrophy, tumors)

– Dynamic stabilizer—extensor mechanism


Patellar Conditions (cont’d)Patellar Conditions (cont’d)Extensor mechanism


Patellar Conditions (cont’d)Patellar Conditions (cont’d)

• Patellofemoral stress syndrome

– Mechanism

• Poor patellar tracking due to weak VMO or tight lateral structures



• Patellofemoral stress syndrome (cont’d)

– S&S

• Dull, aching pain, ↑ with sitting, squatting, and descending stairs

• Point tenderness—lateral facet of the patella

• Pain with manual patella compression into trochlear groove



• Patellofemoral stress syndrome (cont’d)

– Management:

• Standard acute; NSAIDs

• Physician referral



• Chondromalacia

– Degeneration in articular cartilage of patella

– Due to abnormal excursion & compressive forces



• Chondromalacia (cont’d)

– S&S:

• Anterior knee pain and crepitus w/ walking stairs or deep knee bends

• Pain and crepitus increase w/ active & resisted knee extension.

• Localized pain and tenderness on the medial and lateral patellar borders.



• Chondromalacia (cont’d)

– Management

• Standard acute

• Physician referral



• Patellar instability and dislocation

– Displacement of patella due to internal or external forces

– MOI: deceleration combined with a cutting motion



• Patellar instability and dislocation (cont’d)

– S&S subluxation

• Transient partial displacement; acute or intermittent with spontaneous reduction

• Feeling of patella slipping when cutting, twisting, or pivoting




– S&S dislocation

• “Pop”

• Violent collapse of the knee

• Localized tenderness—medial extensor retinaculum

• Loss of limb function

• Effusion




– Management:

• Standard acute

• Immediate physician referral

• Coach should not attempt to reduce



• Patellar tendinitis

– Due to repetitive or eccentric knee extension activities

– S&S

• Initial—pain after activity on inferior pole of patella or distal attachment of patellar tendon

• Progression—pain at start of activity, subsides with warm-up, reappears after activity; eventually pain both during and after activity



• Patellar tendinitis (cont’d)

– S&S (cont’d)

• Pain ascending and descending stairs; pain after prolonged sitting

– Management: standard acute; physician referral



• Osgood- Schlatter disease

– Inflammation or partial avulsion of tibial apophysis due to traction forces

– S&S

• Individual points to tibial tubercle as source of pain

• Tubercle appears enlarged

• Pain during activity and relieved with rest

• Pain at extreme knee extension and forced flexion


Patellar Conditions (cont’d)Patellar Conditions (cont’d)Patellar tendon traction-type injuries



• Osgood- Schlatter disease (cont’d)

– Grade

• 1 – Pain after activity that resolves within 24 hours

• 2 – Pain during and after activity that does not hinder performance and resolves within 24 hours

• 3 – Continuous pain that limits sport performance and daily activities

– Management: do not permit to continue activity until seen by a physician



• Sinding-Larsen-Johansson disease

– Inflammation or partial avulsion of apex of patella due to traction forces

– Usually seen in children 8 to 13 years old involved in running and jumping sports.



• Sinding-Larsen-Johansson disease (cont’d)

– S&S

• Gradual onset of pain

• Pain with palpation of inferior patellar pole with knee extended and patellar tendon relaxed

– Management: do not permit to continue activity until seen by a physician



• Extensor tendon rupture

– Due to powerful eccentric muscle contractions

– S&S

• Partial rupture—pain and weakness in knee extension



• Extensor tendon rupture (cont’d)

– S&S (cont’d)

• Total rupture distal to patella

• High-riding patella

• Palpable defect over the tendon

• Inability to extend knee extension or perform a straight leg raise



• Extensor tendon rupture (cont’d)

– S&S (cont’d)

• Total rupture from superior pole with extensor retinaculum still intact

• Knee extension is possible, but weak and painful

– Management: standard acute; crutches; immediate referral to a physician


Iliotibial Band Friction SyndromeIliotibial Band Friction Syndrome

• Band drops behind lateral femoral epicondyle with knee flexion, then snaps forward over epicondyle during extension

• Due to excessive compression and friction

• Associated with overuse, abnormal biomechanics, and poor flexibility


Iliotibial Band Friction Syndrome (cont’d)Iliotibial Band Friction Syndrome (cont’d)

Iliotibial band



• S&S

– Pain with running progresses from not restrictive to restrictive even with ADLs

– initial lateral ache progresses into a more painful, sharp, and localized discomfort over the lateral femoral condyle just above the lateral joint line

– Flexion and extension of the knee may produce a creaking sound



• Management:

– Acute

– NSAIDs

– Do not permit to continue activity until seen by a physician


Fractures and Associated ConditionsFractures and Associated Conditions

• Avulsion fracture

– Due to direct trauma, excessive tensile forces, overuse

– S&S: localized pain and tenderness over the bony site


Fractures and Associated Conditions (cont’d)


• Epiphyseal and apophyseal fracture

– Tibial tubercle fracture

• MOI

• Forced flexion of knee against a straining quadriceps contraction

• Violent quadriceps contraction against a fixed foot




• Epiphyseal and apophyseal fracture

• S&S

• Pain, ecchymosis, swelling, and tenderness

• Difficulty going up and down stairs

• knee extension painful and weak

• Larger fractures involving extensive retinacular damage

• Patella rides high

• Knee extension is impossible




• Epiphyseal and apophyseal fracture (cont’d)

– Distal femoral epiphyseal fracture

• MOI: varus or valgus stress applied on a fixed, weight-bearing foot

– S&S:

• Pain around knee

• Unable to bear weight




• Stress fractures

– Common areas

• Femoral supracondylar region

• Medial tibial plateau

• Tibia tubercle




• Stress fractures (cont’d)

– Occur when:

• Load on the bone is increased

• Number of stresses on the bone increases (e.g., changes in training intensity, duration, frequency)

• Surface area of the bone receiving load decreases




• Stress fractures (cont’d)

– S&S:

• Localized pain before and after activity

• Relieved with rest and non–weight bearing




• Chondral fracture (involves articular cartilage)

• Osteochondral fracture (involves articular cartilage and underlying bone)

– Due to compression from direct blow to knee causingshearing or forceful rotation

Osteochondral fracture




• Osteochondral fracture (cont’d)

– S&S

• Painful “snap”

• Considerable pain & rapid swelling

• Displaced fracture: locking; crepitus




• Fracture management

– Standard acute

– Use of crutches

– Immediate physician referral

• Stress fracture management



Coach and Onsite AssessmentCoach and Onsite Assessment

• S &S that require immediate physician referral

– Obvious deformity suggesting a dislocation or fracture

– Significant loss of motion or locking of the knee

– Excessive joint swelling

– Gross joint instability

– Reported sounds, such as popping, snapping, or clicking, or giving way of the knee


Coach and Onsite Assessment (cont’d)Coach and Onsite Assessment (cont’d)

• S &S that require immediate physician referral (cont’d)

– Possible epiphyseal injuries

– Abnormal sensations in the leg or foot

– Any unexplained or chronic pain that disrupts an individual’s play or performance

• Refer to Application Strategy 15.2

chapter 15 knee conditions

Documents