The Knee: Anatomy and Injuries. 2 Joints at the Knee Tibiofemoral Joint – formed between tibia and...

The Knee: Anatomy and Injuries

2 Joints at the Knee Tibiofemoral Joint – formed between

tibia and femur A HINGE JOINT Patellofemoral joint – formed

between the patella and the femur A GLIDING JOINT

Skeletal Anatomy Femurproximal – head and neck of

femur, greater trochanter

distal – medial and lateral condyles and

epicondyles

Patella – largest sesamoid bone in body

Tibia – tibial plateau forms knee joint with femur

The fibula is not a part of the knee joint

http://uwmsk.org/RadAnatomy.html

Muscles that move the knee and thigh The Quadriceps – Knee Extension

1. Vastus Medialis2. Vastus Lateralis3. Vastus Intermedius4. Rectus Femoris – 2 joint muscle that also acts as a

hip flexor http://www.bodybuilding.com/exercises/detail/view/name/leg-extensions

The Hamstrings- knee flexion

3 muscles:1. Biceps Femoris2. Semimembranosus3. Semitendinosus

http://www.bodybuilding.com/exercises/detail/view/name/lying-leg-curls

The Adductors (Groin)Adduct the thigh

1. Adductor Longus2. Adductor Magnus3. Adductor Brevis4. Gracilis

http://www.5min.com/Video/Adductor-exercise-1924

The Sartorius: - flexes,

abducts, and laterally rotates thigh

- longest muscle in the body, “tailor’s muscle”

- Crosses hip and knee joint

The Iliotibial Tract(IT Band)

- neither a muscle or tendon, but a long, thick band of tissue that inserts into the lateral tibia (Gerdy’s Tubercle)

What muscles can you identify?

The Major Knee Ligaments

1. ACL – Anterior Cruciate Ligamentprevents anterior motion of tibia

2. PCL – Posterior Cruciate Ligamentprevents posterior motion of tibia

3. MCL – Medial Collateral Ligament4. LCL – Lateral Collateral Ligament

ACL and PCL run from femur to tibia and form an X inside the knee

The Collateral Ligaments

MCL:- Medial Collateral

Ligament- Runs from

medial femur to medial tibia

LCL:- Lateral Collateral

Ligament- Runs from lateral

femur to head of fibula

The Meniscus

A “c”-shaped piece of fibrocartilage located in the knee joint between the femur and attached to the top of the tibia

Cartilage = meniscus

Differences between medial and lateral Medial

- larger and more C-shaped

- more firmly attached to tibia - has attachments to MCL

Lateral

- smaller and more round or O-shaped- not firmly attached to tibia and LCL

Blood Supply to the Meniscus Mostly avascular – little or no blood

supply Only the outer 20% has a blood

supply* Does not have the ability to heal

itself unless there is a small tear in the outer 20%

Functions of Meniscus

1. Stability2. Shock absorption3. Lubrication and nutrition4. Allows adequate weight distribution

Normal Torn

Total Knee Joint Replacement Surgery to replace a painful

damaged or diseased knee joint with an artificial joint (prosthesis)

Artificial hip invented 1962 1969 – first artificial knee in USA

The Knee Surgery Thin layer of bone removed from

femur – thin metal replaces it Upper layer of tibia replaced with

plastic Back of patella replaced with plastic Parts fastened with “bone cement”

Risks of Knee Joint Replacement Blood clots in large veins Infection Stiffness Implant Loosening/Failure

- more of a problem in younger patients

Knee Injuries and Conditions

Genu Valgum: “knock knees”

Genu Varum: “bowlegs”

Genu Recurvatum:

hyperextension of the knee joint

Patellofemoral Disorders Problems with patella – most common

cause of knee pain Anatomy:

- Patella is a sesamoid bone formed in Quad tendon- Patellofemoral joint – patella and femur- Compression forces –

<body weight during walking2.5 x body weight during stairs

Patellar Tendonitis “Jumper’s Knee” Inflammation and degeneration of

the tendon that connects the kneecap (Patella) to the shin bone (Tibia).

Chondromalacia Damage to the cartilage under the

kneecap Causes: abnormal patellar tracking Most Common Symptom: Knee pain when

walking up and down stairs Prevention: strengthen quads

Minimize squats, downhill running, biking with low seat

Chondromalacia

Patellar Dislocation Involves the

patella sliding out of its position on the knee.

Caused by direct blow or abnormal twisting of the knee

Usually lateral

Osgood-Schlatter Disease

1. Painful swelling over tibial tuberosity(patellar tendon insertion)

2. Usually occurs between 9-13 years of age

3. Pain increases with activity

The Chopat Strap

Iliotibial Band Friction Syndrome Occurs where IT Band rubs over

femur at the knee joint Common in running (esp. downhill)

or any activity with repetitive flexion Hills or stairs increase pain Lots of IT Band stretching

Popliteal Cyst “Baker’s Cyst” Fluid accumulation in posterior knee

(popliteal space) Patient usually complains of a mass

behind the knee

Prepatellar Bursitis “Housemaid’s Kne

e” Tender swelling

over the kneecap (prepatellar bursa)

Pes Anserine Bursitis Inflammation of a bursa in your knee. The

pes anserine bursa is located on the inner side of the knee just below the knee joint.

Tendons of three muscles attach to the shin bone (tibia) over this bursa

SGT: Sartorius, Semitendinosis, Gracilis

Knee Sprains

ACL Sprain >200,000 injuries/year >100,000 reconstructions/year Higher incidence in females Males = contact

Females = noncontact

http://www.youtube.com/watch?v=PzpOEdUdoM4

ACL Sprain1. MOI: twisting of knee

forced hyperextension lateral blow to knee

*foot must be firmly anchored to playing surface

2. 50% of people describe a “pop” in knee 3. Knee fills with blood quickly

Hemarthrosis4. Usually immediate loss of motion5. Knee feels unstablehttp://www.youtube.com/watch?v=uuoj_HFG5Z0&feature=fvst

Anterior Drawer Test:

examiner attempts to slide the tibia forward which may indicate a torn ACL ligament

http://www.youtube.com/watch?v=1iWqUsd1aqY

ACL Sprain Who needs

surgery? - Activity level? - Level of

Competition - Age?

ACL Surgery Arthroscopic Graft options Patellar Tendon

SemitendinosusGracilisCadaverSynthetic

http://www.youtube.com/watch?v=Xsq0sQp6DwUhttp://www.youtube.com/watch?v=dZiDd6e4drc

PCL Sprain

1. MOI: excessive hyperextension hyperflexion

tibia forced posteriorly (blow to front of knee)“dashboard knee”

Possibly 90% of all PCL injuries due to motor vehicle accidents?

2. Mild hemarthrosis3. Posterior knee pain4. Walk with knee

slightly flexed, avoid full extension

5. Posterior sag of tibia6. Surgery?

MCL Sprain MOI: Blow to the outside of the

knee = Valgus Force Possible overuse – breaststroke in swimmers

Commonly associated with meniscal injuries – attached to medial meniscus

No surgery

MCL Sprain

Valgus Stress Test:tests for injury to the MCL ligament

LCL Sprain MOI: Blow to inside of the knee –

Varus force

Grade III tear may require surgery

Varus Stress Test:tests for injury to the LCL ligament

Injuries to the Meniscus

1. MOI: Rotation of the knee as the knee extends during rapid cutting or pivoting

2. Signs and Symptoms:- pain- joint line tenderness- catching or locking- knee buckling or giving way- swelling- incomplete flexion- clicking on stair climbing

3. Surgery?Meniscectomy: removal of the

meniscus- Total meniscectomy =

osteoarthritis

Depends on location of tear, type of tear, and blood supply

Types of Meniscal Tears- bucket handle- Flap tear- Transverse tear- Horn tear

Tests for Meniscal Tears Apley’s

Compression

“The Unhappy Triad” Tear of the medial

meniscus, anterior cruciate ligament (ACL), and medial collateral ligament (MCL)

The Knee: Anatomy and Injuries. 2 Joints at the Knee Tibiofemoral Joint – formed between tibia and...

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