KNEE ANATOMY-By Abu Saquib

8/11/2019 KNEE ANATOMY-By Abu Saquib

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KNEE ANATOMY



INTRODUCTION

• Hinge type Synovial joint.

• Can bear load more than 8 times of body

weight.



GENRAL ANATOMICAL TERMS FOR KNEE

• ANTERIOR - FRONT OF KNEE

• POSTERIOR - BACK OF KNEE

• MEDIAL – SIDE OF KNEE CLOSSEST TO OTHER KNEE

• LATERAL – SIDE OF THE KNEE FARTHEST FROM OTHER SIDE



CONSTRUCTION

BONES

MUSCLE

LIGAMENTS

CARTILAGES

BURSA



BONES

FEMUR

TIBIA

FIBULA

PATELLA





Bones of the Knee

The bones give strength, stability and

flexibility in the knee.•Femur :

Commonly known as thigh bone

Largest, longest & strongest

bone in body.Have two round end called

condyles with a groove in center.

•Tibia :

Commonly known as shim bone.Connect from knee to ankle.

Have top flat surface.

Flat surface act as a base of

meniscus.



•Patella:

Commonly known as knee cap.

It’s flat and triangular in size.

Relive friction between bone

and muscle during movement.

Protect knee joint.

•Fibula:

Long thin bone in the lower leg.

Not directly a part of knee joint.

Act as a support for tibia.



MUSCLES

• QUADRICEPS - It is a groupof 4 muscle present in front of

the thigh and are responsible

for straitening the knee by

bringing the bend knee to

straight position.

• HAMSTRINGS - It is a group

of 3 muscle present in the

back of the thigh and control

the knee moving from straight

to bend position.



LIGAMENTS

Its function is to attachbones to bones and give

strength and stability to

the knee, as the knee

have very less stability.Ligaments are strong,

tough band that are not

flexible. Once stretched

they tend to stay

stretched and if stretched

too far, they snap



LIGAMENTS•MEDIAL COLLATERAL LIGAMENT –

Attached medial femur to medial tibia and limits sidewaymotion.

•LATERAL COLLATERAL LIGAMENT –

Attached lateral femur to lateral tibia and limits sideway

motion

• ANTERIOR CRUCIATE LIGAMENT – Attaches tibia and femur in centre of the knee and limits

rotation as well as forward motion of tibia.

•POSTERIOR CRUCIATE LIGAMENT –

It is the strongest attaching the tibia and femur going deepinside the knee locating behind ACL, limiting backward

motion of knee.

•PATELLAR LIGAMENT – Attach the patellar to the tibia



•FIBROUS CARTILAGE (the meniscus) – Has tensile strength and can resist pressure.

•HYALINE CARTILAGE (Articular cartilage) –

Covers the surface along which the joints move.

CARTILAGE



CARTILAGES

•Cartilage is a thin, elastic tissue that protects the bone

and makes certain that the joint surfaces can slide easilyover each other. Cartilage ensures smooth knee

movement.

•Cartilage will wear over the years.

•Cartilage has a very limited capacity for self-restoration.

• The newly formed tissue will generally consist for a

large part of fibrous cartilage of lesser quality than theoriginal hyaline cartilage. As a result, new cracks and

tears will form in the cartilage over time.



• MEDIAL MENISCUS

• LATERAL MENISCUS

MENISCUS



• Shaped like a shallow socket.

• Rubbery in nature.

• Act as a shock absorber(more than 10xBW)

• Distribute the load from femur to tibia.

• Decrease friction by 20%.

• Increase contact area by 70%.

MENISCUS





BURSA

A bursa is a small fluid-filled sac lined by synovial

membrane with an inner

capillary layer of viscous

fluid (similar in consistencyto that of a raw egg white).

It provides a cushion

between bones and

tendons and/or muscles

around a joint. This helps toreduce friction between the

bones and allows free

movement.



JOINTS OF THE KNEE

•Tibiofemoral jointModified hinge joint.

Dual condyloid

articulation b/w medial

and lateral condyles offemur and the tibia.

Articulating surface are

not congruent.



JOINTS OF THE KNEE

•Patellofemoral joint

Articulation b/w the

patella and femur.

The patella improves

the mechanicaladvantage of the knee

extensors by as much as

50%.



KNEE MOVEMENTS



AXIS OF ROTATION



AXIS OF ROTATION



KNEE GONIOMETRY

• Flexion

– 0-130-140 degrees

• Extension

– 0 degree

• Screw Home Mechanism



SCREW HOME MECHANISM

•Locking mechanism as the kneenears its final extension

Automatic rotation of the tibia

externally (approx. 10 degrees)

during the last 20 degrees of knee

extension

•Forms a close-packed position for

the knee joint

•Femoral condyles are a different size

Causes internal rotation whenthe knee is flexed and external

rotation when the knee is

extended



KNEE ROTATION

FlexionExternal

Rotation

Internal

Rotation

Extension







Patella migrates posteriorly from extension to flexion

30 60 90

Patellar Translation



Mechanical Function of Patella

• Increases angle of pull of

quads on tibia, improves the

ratio of motive: resistive torque

by 50%• Centralizes divergent tension

of quads into a single line of

action

• Some protection of anterioraspect of knee

without patella with patella



Mechanical Function of Patella

• Patella contributes to

quadriceps moment arm

– 13% at 90o

– 31% at 0

o

• No angle without patella

& therefore no

compressive resultant

force



Patellofemoral Compressive Force

Mechanics

• PFC force with flexion

– 0.5 x BW gait (walk)

– 3.4 x BW stairs

– 8.8 x BW squatting



Q-Angle

• The Q-angle is the angle formed by

– A line from the anterior superior

spine of the ilium to the middle of

the patella

– A line from the middle of the

patella to the tibial tuberosity



Q-angle

• Knee in extension

– Normal – males 13 degrees

– Normal - females – 18 degrees

• Knee in 90 degrees flexion – Both genders – 8 degrees



A typical Q-angles

bowleggedness knock-knees

Genu Recurvatum

knee hyperextension



Posture & WB Forces

• The mechanical axis of TF joint is the weight bearing linefrom the center of femoralhead to superior talus center

• Allows WB instance of the

medial = lateral Tibiofemoralcompartments



• Increase in valgus results:

– Compression overload to the

lateral Tibiofemoral

compartment – Distraction overload to medial

Tibiofemoral compartment

Posture &WB Forces



• Decrease in valgus results

– Compression overload to the

medial Tibiofemoral

compartment – Distraction overload to lateral

Tibiofemoral compartment

Posture & WB Forces



Joint Mechanics

• Resultant force has a tendency tolaterally translate the patella



• Laterally displace tibial tubercle – external tibial rotation

– external tibial torsion

• Medially displace patella

– internal femoral rotation – femoral anteversion

Joint Mechanics



Tibial Torsion

• Tibial torsion

– An angle that measures less

than 15 degrees is an

indication of tibial torsion

– Inward twisting of the tibia

(and is the most common

cause of intoeing)



KNEE FUNCTION

•The quadriceps Mechanism is made up of patella, patellar

tendon and the quadriceps muscle on the front of upper

leg. The patella fits into the patellofemoral groove on the

front of the femur and act like a fulcrum to give the leg its

power. The patella slides up and down the groove as theknee bends. When the quadriceps muscle contract they

cause the knee to straighten. When they relax, the knee

bend.

•The hamstring and calf muscles help flex and support the

knee.



Movements of the knee

• Flexion

– hamstrings

– assisted by:

• gracilis• sartorius

• popliteus

• gastrocnemius





Gracilis

Sartorious



Popliteus



Gastrocnemius



Muscle Pull



Movements of the knee

• Extension

– quadriceps:

• rectus femoris

• vastus lateralis

• vastus medialis

• vastus intermedius



Rectus femoris



Vastus lateralis

Vastus intermedius

Vastus medialis



Muscle Pull



Loads on Knee

• Forces at Tibiofemoral Joint

– Shear stress is greater during open kinetic chain

exercises such as knee extensions and knee

flexions

– Compressive stress is greater during closed kinetic

chain exercises such as squats and weight bearing

exercises



Loads on Knee

• Forces at Patellofemoral Joint

– With a squat, reaction force is 7.6 times BW on this

joint

• Beneficial to rehab of cruciate ligament or

Patellofemoral surgery



PROBLEMS IN THE KNEE

The knee doesn’t have much protection from trauma or

stress. In addition to wear and tear on the knee, sportsinjuries are the source of many knee problems.

•Symptoms:

Dull, sharp, constant or any type of pain.

Range of motion may vary, i.e. too little or too much.Grinding or popping sound coming from knee.

Week muscle.

Knee locking.

•Solutions: Some knee problems only need rest and ice, others need

physical therapy or even surgery.



Swelling: There are two types of swelling.

•Knee producing too much synovial fluid

•Bleeding into the joint (hemarthrosis).

Swelling within the first hour of an injury is usually from

bleeding. Swelling from 2-24 hours is more likely to be from

the joint producing large amounts of synovial fluid trying to

lubricate an abnormality inside the knee.

Effect:

•Chronic swelling can distend the knee.

•Prohibit full range of motion.

•If the cause of the swelling is blood, the blood can be

destructive to the joint.

Therapy:

•R.I.C.E (Rest Ice Compression Elevation)



Locking: Locking is when something is keeping the knee

from fully straightening out. This is usually a loose body in

the knee. The loose body can be as small as a grain of sandor as big as a quarter. The best treatment is removal of the

loose body by arthroscopy. Another type of locking is when

the knee hurts so bad that you just won’t use it. The best

treatment here is rest and maybe some ice; swelling is not

usually present.

Giving Way: If your kneecap slips out of is groove for an

instant, it causes your thigh muscles to loose control causing

the feeling of instability—that is, you don’t feel like your knee

is stable, won’t support your weight—and you usually try tograb hold of something for support. Giving way can also be

caused by weak leg muscles or an old ligament injury.



Snaps, Crackles and Pops: Noises coming from knee

without pain are likely nothing to worry about. Sometimes thenoise is caused by loose bodies that just float around and are

not causing pain or injury to the knee. However, If you have

pain, swelling or loss of knee function, you should see an

orthopedist. The most common cause—chondromalacia

patella—is caused by an injury. Another common cause is a

dislocating kneecap—that is, a kneecap that keeps slipping out

of its groove. Pops without trauma (injury) are not worrisome,

pops with trauma can mean ligament tears. Crackling, grinding

or grating (crepitus) means there is a roughness to the bonesurfaces and likely from degenerative disease or wear-and-

tear arthritis (osteoarthritis).



Pain and Tenderness:. Where and how bad the pain iswill help find the underlying cause. It also helps to know what

caused it and what makes it hurt. Pain that gets worse with

activity is often tendinitis or stress fractures. Pain and

tenderness accompanied by swelling can be more serious

such as a tear or sprain. Some pain can be caused by musclesspasms associated with trauma.



The most common knee problems are:

•Arthritis.

•Torn ligament.

•Torn meniscus.

•Chondromalacia.

•Loose body inside the knee joint.

ARTHRITIS



ARTHRITIS

There are three basic types of arthritis:

•Osteoarthritis.Most common type.

Slowly degenerate knee joint bone tissues.

Mostly occur in middle or old age people.

•Rheumatoid Arthritis.Inflammatory type.

Affect both knee.

Can occur at any age.

•Post-traumatic ArthritisSimilar to osteoarthritis.

Occur after an injury of knee.

May develop years after a fracture, ligament injury, or

meniscus tear



HEALTHY KNEE ARTHRITIS

SYMPTOMS



Arthritis causes joint pain, swelling, stiffness, and limited

movement. Symptoms can include:

Joint pain.Joint swelling.

Reduced ability to move the joint.

Redness of the skin around a joint.

Stiffness, especially in the morning.

Warmth around a joint.

CAUSES

Genetic.

Age.

Weight.Previous injury.

Heavy sports.

Illness or infection.

TREATMENTS



Non surgical treatment fall in four major group:

Lifestyle modifications.

Exercise.Supportive devices.

Other methods.

Surgical Treatment

Arthoscopy.

Osteotomy.

Arthroplasty (total knee replacement).

Knee Cartilage replacement*.

TORN LIGAMENT



Sudden start-stop movements

and quick changes in directionare common causes of ligament

injuries. A torn knee ligament can

cause pain, swelling or difficulty

in walking. Ligament sprains can

take 4-6 weeks for recovery.Ligament injuries can also be

partial or complete tears. A torn

ligament needing reconstructive

surgery can take a year to heal.In addition, damage to the

meniscus may be found and

repaired during arthroscopy.

TORN LIGAMENT

RECONSTRUCTED ACL



TORN MENISCUS



Twisting the knee joint is the most common cause of a tornmeniscus. This can happen during sports or even during

normal daily activity. The meniscus also becomes softer with

age, making it easier to tear. Tears can occur along the edge of

the meniscus or larger tears can occur deeper into the

meniscus. A torn meniscus can cause catching or locking of theknee, giving way or buckling (instability) of the knee, pain or

swelling. The size and location of the tear determine both

treatment and recovery. Small tears need 4-6 weeks for

recovery while repair of larger tears can take 3 months or more.

TORN MENISCUS

MENISCUS TEAR



MENISCUS TEAR

MENISCUS REPAIR OR REMOVAL



MENISCUS REPAIR OR REMOVAL

CHONDROMALACIA



Chondromalacia can be caused by overuse or injury to thekneecap and is a condition where the articular cartilage of the

knee bones softens. It is most common on the back of your

kneecap where the kneecap rubs with straightening of the

knee. As the cartilage softens, it wears away more easily during

joint movements. The cartilage can also be damaged bydirectly injuring the knee. Or the cartilage may just thin with

age, which can cause catching or locking of the knee, giving

way or buckling of the knee (instability), pain or swelling.

CHONDROMALACIA

CARTILAGE DEFECT



CARTILAGE DEFECT

LOOSE BODY (Joint Mouse)



Any free-floating object in the synovial fluid of the knee isknown as a loose body or joint mouse. It can be a fragment of

bone, cartilage, or meniscus. It can also be a piece of glass,

metal or any foreign object. A loose body isn’t usually

noticeable until it lodges somewhere in the joint. Your

symptoms can change depending upon the exact locationwithin your knee. A loose body can cause catching or locking of

the knee, giving way or buckling of the knee (instability), pain or

swelling.

LOOSE BODY (Joint Mouse)

LOOSE BODY REMOVAL



LOOSE BODY REMOVAL

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KNEE ANATOMY-By Abu Saquib