Knee Region

Knee

Largest joint in the body

Most complex joint in the body

Femur (distal) - condyles

Tibia (proximal)

Patella

3 bones of the Knee

Tibia

2nd largest joint in the body

Flexion/extension + rotation

2 degrees of freedom

Medial Tibiofemoral Joint

Lateral Tibiofemoral Joint

Patellofemoral Joint

3 articulations

Osteoarthritis

Arthritis of the knee (Medial Tibiofemoral Joint)

Chondromalacia Patella

Patellofemoral Joint

Cinema/Tear Sign

Patellofemoral Joint Inflammation d/t sitting

Femur

Distal Aspect

Medial Condyle

Mahaba at Malaki

Lateral Condyle

Shorter and smaller

Mattress Effect (Lateral Condyle)

To prevent the lateral dislocation of othe patella

Tibia

Proximal Aspect

Tibia Plateau/Condyles

Predominantly flat

Lateral condyle of femur to lateral condyle of tibia

Medial condyle of femur to medial condyle of itbia

Femoral condyles to Tibial condyles

With slight convexity at anterior/posterior margins (meniscus in between to increase congruency)

Knee Joint

Type: Modified Hinge

Flexion and Extension, Rotation

25 degrees flexion (lateral)

OPP

Full extension + tibial rotation

CPP

Flexion > Extension

CP

Axial Rotation

Knee during extended (-) rotation

Knee flexed 90 degrees ligaments slacked can be rotated to left and right with a total of 40 degrees

40

The total axial rotation of the knee

Menisci

AKA Semilunar Cartilages

Generally avascular (outer 1/3 is avascular)

Function of Menisci

Increased congruency

Shock absorption

Lubrication

Decreased friction

Medial Meniscus

Shape: C-shape (6mm)

Mobility: less mobile

Injury: increased injury

Ligament attachment: ACL, MCL

Muscle attachment: Semimembranosus

Lateral Meniscus

Shape: O shape

Mobility: more mobile and less fixed (12mm)

Injury: decreased injury (CKC)

Ligament attachment: PCL

Muscle attachment: Popliteus

CKC

MOI of meniscal damage

Lateral rotation and extension

Taut position

Foot Planted

Foot Planted

Unhappy Triad of O’donoghue/Terrible Triad

Medial Meniscus

ACL

MCL

Coronary Ligament

Menisco Tibial

Meniscofemoral Ligament

Only the lateral meniscus

Humphrey

Anterior

Wrisberg

Posterior

Knee Stabilizers

Collaterals

Cruciates

Collaterals - Medio-lateral Stabilizers

Frontal Plane Stability

MCL

Tibial Collateral Ligament

ST: Valgus stress test - abduction

LCL

More commonly injured

Fibular Collateral Ligament

ST: Varus Stress Test

MCL

A forceful blow from the lateral aspect of the knee

Swimmer’s Knee

Kicking when swimming causing repetitive trauma to MCL

Pellegrini Streda

Ossification of MCL

EXCOLTA (Lateral rotation and extension_

Tautest Position of MCL

Cruciates

Anteroposterior

Rotatory

ACL

Posterior, Lateral, Superior (PLS)

PCL

Superior, Anterior, Medial (SAM)

Intracapsular and Extrasynovial (ICE)

Location of ACL and PCL

ACL

Most common injured ligament of the knee

MCL

2nd most common injured ligament of the knee

PCL

Stoutest or strongest ligament

Extension and Internal Rotation

Tautest position of ACL

30-60 degrees of flexion

Slackest position

ACL Prevented Motions

Anterior Tibial Translation (OKC)

Post-Femoral Translocation (CKC)

PCL Prevented Motions

Anterior Tibial Translation (CKC)

Post-Femoral Translocation (OKC)

Tibia

A - ACL

P - PCL

Femur

A - PCL

P - ACL

ACL

Basketball player is running then suddenly stops causing hyperextension of the knee with quads contraction

PCL

While driving a car with sudden stop causing anterior tibia to hit the dashboard

PCL

Basketball player suddenly jumps and landed on planted feet, knee flexed

Oblique Popliteal Ligament

Tendinous expansion of semimembranosus tendon (medial hamstrings)

Reinforces the anterolateral aspect of the knee joint

Gerdy’s Tubercle

TGL and G. Max > ITB > Tibia (anterolateral)

ITB Friction Syndrome

Repetitive microtrauma of the ITB common in runners

Coronary Ligament

Meniscotibial Ligament

Meniscofemoral Ligament (only for the Lateral Meniscus)

Anterior Ligament of Humphrey

Post. Ligament of Wrisberg

Screw Home Mechanism

Terminal rotation of the knee

Screw Home Mechanism

Pure mechanical event that cannot be prevented or voluntarily produced; locking mechanism

Happens during the last 20 degrees of knee extension

Knee Extension (LOCK)

CKC - FIR

OKC - TER

Knee Flexion (UNLOCK)

FER

TIR

Key - Popliteus

CKC FIR

Femur IR, CKC Fer - Femur ER

OKC Ter Tibia ER

OKC TIR - Tibia IR

Sitting from standing position

ER of Femur can be seen in this activity

Bursae

Extension of the synovium

Suprapatellar Bursa

Above the patella

Between quads tendon and anterior femur

Prepatellar Bursa

Front of Patella

Most common inflamed knee bursa

Housemaid’s Knee

Inflammation of Prepatellar Bursa

Infrapatellar Bursa

Superficial - anterior to patellar tendon

Vicar’s Knee

Nun’s Knee

Clergyman’’s Knee

Inflammation of the Infrapatellar Bursa

Tall kneeling position

Popliteal Bursa

Commonly inflamed in RA of the knee

Baker’s Cyst

Inflammation of the Popliteal Bursa

Biceps Femoris (Lateral Hamstrings)

O: Long head: ischial tuberosity, short head: linea aspera of posterior femoral shaft

I: Fibular head

N: Long head: tibial portion of sciatic nerve, short head: Common Peroneal Nerve of Sciatic Nerve

A: Hip extension, knee flexion, ER of tibia

Hamstrings

Primary knee flexor

Hamstrings

Biceps Femoris (lateral)

Medial Hamstring - Semitendinosus, Semimembranosus

Sartorius

Gracillis (hamstring portion, not included in the knee region, does not flex the knee)

Sartorius

Longest muscle n the body

(+) Tripod sign

Tightness

Semitendinosus

Most prominent tendon at the back of the knee

Deceleration/terminal swing, eccentric contraction

Peak activity of the Hamstrings

Pes Anserine/Goose Foot/Inverted Tripod Group

Sartorius and Gracilis

Gracillis

2 jointed muscle of adductors

Phelp’s Test

Special test for tightness of Gracillis

Popliteus

Key to unlock the knee during knee flexion

Gastrocnemius

2 head medial head (from medial condyle) and lateral head (from lateral condyle)

Knee can also rotate

Muscles inserting at the medial site are medial/internal rotators of the leg

Muscles inserting at the lateral side are lateral/external rotators of the leg

Achilles Tendon

Strongest Tendon

Gastrocnemius

O: Lateral head - lateral femoral condyle, Medial head - Medial femoral condyle

I: Achilles tendon

N Tibial Nerve

A: Knee flexion, ankle DF

Semitendinosus/Semimembranosus (Medial Hamstrings)

O: Ischial Tuberosity

I: Medial Tibia

N: Tibial portion of Sciatic Nerve

A: Hip extension, knee flexion + medial rotation

Sartorius/Tailor’s Muscle

O: ASIS

I: Medial tibia - where SGT muscles are inserted

N: Femoral nerve

A: Hip - FABER, Knee - flexion and IR

Popliteus

O: Lateral femoral condyle

I: Posterior shaft of the tibia

N: Tibial nerve

A: Knee flexion (FER/TIR)

Knee Extensors

Quadriceps :

Rectus Femoris

Vastus Lateralis

Vastus Medialis

Vastus Intermedius

Quadriceps

Primary knee extensors

Most commonly contused

Charley Horse

Contusion of the Quads

Myositis Ossificans

MC site: Quadriceps

Stance Phase- heel strike to foot flat/initial contact to loading response (eccentric contraction)

Peak activity of Quadriceps