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Knee Anatomy& Disorders

By : Nour Abu Al-Shaar

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Knee AnatomyKnee Anatom

y

- The Knee Joint is the largest & most

complicated joint in the body .

- It consists of 3 Joints within a singlesynovial cavity :

1)Medial Condylar Joint : Between the medialcondyle of the femur & the medialcondyle of the tibia .

2)Latral Condylar Joint : Between the lateral

condyle of the femur & the lateralcondyle of the tibia .

3)Patellofemoral Joint : Between the patella &the patellar surface of the femur .

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Types :- 1 & 2 : Hinge .

- 3 : Planar gliding .

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Anatomical Components ofAnatomical Components of

the Kneethe Knee

1) Capsule : Surrounds the sides &posterior aspect of the joint Onthe frontal side , the capsule isabsent .

On each side of the patella , the

capsule is strengthened by thetendons ofVastus Lateralis &Vastus Medialis .

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2) Ligaments :

A] ExtracapsularLigaments :

- LigamentumPatellea

((a continuation of

the QuaricepsFemoris muscle ))

- Lateral CollateralLig.

- Medial CollateralLig.

- Oblique PoplitealLig

(( derived from the

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B ) Intracapsular Ligaments : Cruciate Ligaments : 2 strong ligaments that cross each

other within the joint cavity .

~ Anterior Cruciate Ligament (ACL) := Attached to the anterior intercondylar area

of the tibia , passes upward , backward &

laterally to get attached to the lateral femoral

condyle .= Prevents posterior displacement of the

femur (( With the knee joint flexed , the ACL

prevents the tibia from being pulled anteriorly)) .

~ Posterior Cruciate Ligament (PCL) :=Attached to the posterior intercondylar area of the tibia ,

passes upward , forward , & medially to get attached to themedial femoral condyle .

= Prevents anterior displacement of the femur (( With the kneejoint flexed , the PCL prevents the tibia from being pulled

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Th di l d l l i i 2 C h d

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- The medial and lateral menisci are 2 C-shapedsheets of fibrocartilage between the tibial & femoralcondyles

- Their peripheral border is thick & attached to the

capsule ,their inner border is thin & forms a free edge .

- Each meniscus is attached to the upper surface of thetibia by anterior & posterior horns .

-They are connected to each other by the transversaligament and to the margins of the head of the tibiaby coronary ligaments.

-There are several differences between the medial andlateral meniscus, both anatomically (how they look)and functionally (how they work). Since the medialmeniscus is attached to the joint capsule all aroundits outer edge, it does not slide much in any directionand is therefore more likely to tear. The lateralmeniscus is more rounded, and there is a sectionwhere it is not attached to the joint capsule wall.

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One differentiatesmorphologically (= related tothe cellular structure) :

1. The meniscus base, which isin immediate contact withthe joint capsule (red zone)

2. The intermediate meniscusregion (light red zone)

3. The white fringes.

Vessels penetrate through the

red zone until the centralthird of the meniscus(designated as light red) Bycontrast, the white fringeindicates no vessels. It isnourished via the joint fluid

(= joint lubrication).

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Thick, circular-triangularbone which articulates with thefemur and covers and protects the anterior articularsurface of the knee joint.

It is the largest sesamoid bone .

Anterior surface

It can be divided into three parts:The upper third is coarse, flattened,

and rough; it serves for the attachment

of the tendon of the quadriceps and often has exostoses.

The middle third has numerous vascularcanaliculi.

The lower third includes the distal apex which serves asthe origin of the patellar ligament.

Posterior surface

The upper three-quarters articulates with the femur and is

subdivided into a medial and a lateral facet by a verticalledge which varies in shape.

http://en.wikipedia.org/wiki/Bonehttp://en.wikipedia.org/wiki/Femurhttp://en.wikipedia.org/wiki/Knee_jointhttp://en.wikipedia.org/wiki/Sesamoid_bonehttp://en.wikipedia.org/wiki/Exostosishttp://en.wikipedia.org/wiki/Vascularhttp://en.wikipedia.org/wiki/Canaliculus_(bone)http://en.wikipedia.org/wiki/Canaliculus_(bone)http://en.wikipedia.org/wiki/Vascularhttp://en.wikipedia.org/wiki/Exostosishttp://en.wikipedia.org/wiki/Sesamoid_bonehttp://en.wikipedia.org/wiki/Knee_jointhttp://en.wikipedia.org/wiki/Femurhttp://en.wikipedia.org/wiki/Bone

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It is attached to the tendon of thequadriceps femoris muscle, whichcontracts to extend/straighten theknee. The vastus intermedialis muscleis attached to the base of patella. Thevastus lateralis and vastus medialis

are attached to lateral and medialborders of patella respectively.

The knee is normally in slight valgus sothere is a natural tendency for thepatella to pulled to the lateral sidewhen the quadriceps muscle iscontracted

The patella is stabilized by the insertionof vastus medialis and the prominence

of the anterior femoral condyles, whichprevent lateral dislocation duringflexion.

When injuries occur, all structures aresimultaneously affected.

These ligaments hold the patella in placeduring static and dynamic phases.

http://en.wikipedia.org/wiki/Tendonhttp://en.wikipedia.org/wiki/Quadricepshttp://en.wikipedia.org/wiki/Kneehttp://en.wikipedia.org/wiki/Vastus_intermedialishttp://en.wikipedia.org/wiki/Vastus_lateralishttp://en.wikipedia.org/wiki/Vastus_medialishttp://en.wikipedia.org/wiki/Vastus_medialishttp://en.wikipedia.org/wiki/Vastus_lateralishttp://en.wikipedia.org/wiki/Vastus_intermedialishttp://en.wikipedia.org/wiki/Kneehttp://en.wikipedia.org/wiki/Quadricepshttp://en.wikipedia.org/wiki/Tendon

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Innervation of the KneeInnervation of the Knee Femoral Nerve :Common

Peroneal(( Fibular ))Nerve .

Tibial Nerve .

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Knee MovementsKnee Movements

- Flexion : these muscles produce flexion :

Biceps femoris , Semitendinosus ,Semimembranosus , Gracilis, Sartorius ,Popliteus .

~ Flexion is limited by the contact of theback of the leg with the thigh .

- Extension : by the Quadriceps femoris .~ Extension is limited by the tension of all

the ligaments of the joint .

- Medial Rotation : by the Sartorius ,Gracilis , Semtendinosus .

- Lateral Rotation : by the Biceps

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OSTEOARITHRITISOSTEOARITHRITIS

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c/o: middle age patient complainof pain starts insidiously andincrease

slowly over time ( months andyears )

aggravated by exertion andrelieved byrest, with time relief is less and lesscomplete.Stiffness :mainly after rest

Symptoms follow an intermittentcourse with periods of remissionlasts for months

In advance stage : deformity,swelling, muscle wasting and

loss of mobility .No systemic manifestations in

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Osteoarthritis (OA) : a chronicinflammatory joint disorder in whichtheres progressive softening &destruction of the articularcartilage , accompanied by new

growth of cartilage and bone at thejoint margins (osteophytes) and

capsular fibrosis... leading to boneexposure & severe pain .

OA is the most common joint dis.

The knee is the most common site.

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It can be primary or secondary :

Usually its Primary (( Idiopathic ))

& affecting both knee joints((Bilateral)) .

Secondary causes might be :

Trauma , localized or metabolicdiseases , mechanical factors , BoneDysplasia , etc

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Secondary causes of OASecondary causes of OAA. Trauma1. Acute

2. Chronic (occupational,sports)

B. Congenital ordevelopmental

1. Localized diseases: Legg-Calve-Perthes, congenitalhip dislocation, slippedepiphysis

2. Mechanical factors:unequal lower extremitylength, valgus/varusdeformity, hypermobility

syndromes3. Bone dysplasias:

epiphyseal dysplasia,spondyloepiphysealdysplasia,osteonychondystrophy

C. Metabolic1. Ochronosis (alkaptonuria)

D. Endocrine1. Acromegaly

2. Hyperparathyroidism

3. Diabetes mellitus4. Obesity

5. Hypothyroidism

E. Calcium deposition diseases1. Calcium pyrophosphate dihydrate deposition

2. Apatite arthropathy

F. Other bone and joint diseases1. Localized: fracture, avascular necrosis,infection, gout

2. Diffuse: rheumatoid (inflammatory) arthritis,Paget's disease, osteopetrosis,osteochondritis

G. Neuropathic (Charcot joints)

H. Endemic1. Kashin-Beck

2. Mseleni

I. Miscellaneous1. Frostbite

2. Caisson's disease

3. Hemoglobinopathies

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Risk factors:1- age .

The likelihood of developing osteoarthritis increases with age. The

disease is equally common among men and women aged 45-55years. After age 55 years, the disease becomes more common in

women.

2- Racial difference.Knee osteoarthritis appears to be more common in African American

women than in other groups.

3- 2ndy cause e.g hx of trauma .4- obesity.5- family Hx.

Predisposing factors :

1) Articular surface injury .

2)Torn meniscus .

3) Ligament instability .

4) Preexisting deformity .

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OA results from a

disparity between the stressapplied to the articular

cartilage & the ability of the

cartilage to withstand that

stress , due to :

1)Weakening of the articular cartilage ( genetic defectin collagen type ll or inflammatory disorder RA ) .

2) Increased mechanical stress in some parts of the

articular surface .

The abraded bone under a cartilage ulcer may takeon the appearance of ivory (eburnation = thebony sclerosis which occurs at the areas of cartilageloss.). Growth of cartilage and bone at the jointmargins leads to osteophytes (spurs), which alter thecontour of the joint and may restrict movement

http://en.wikipedia.org/wiki/Osteosclerosishttp://en.wikipedia.org/wiki/Osteosclerosis

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- Appositional bone growthoccurs in the subchondralregion

- seen radiographically - .

Synovitis & thickening ofthe joint capsule may occur

& further restrict movement

Periarticular muscle wasting is common &may play a major role in symptoms .

- So , to summarize the cardinal features are:

1) Progressive loss of cartilage thickness .

2) Subarticular cyst formation and sclerosis.

3) Remodeling of the bone ends & osteophyte formation .

4) Synovial irritation (( Synovitis )) .

5) Capsular thickening & fibrosis .

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X-Ray Findings

1- narrowing of jointspace.

2- subarticular cyst

formation andsclerosis.3- osteophyte

formation.4- evidences of

2ndry causese.g. old fracture.

The first two are restricted initially tothe

major load-bearing part of the jointbut

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Pre OpPre Op

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Post Op THRPost Op THR

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ManagementManagement- Early :1) Relieve the pain : by using NSAIDs .

2) Joint mobility : by physiotherapy .3) Reduce the load : by using a walkingstick , soft medical shoes, weightreduction & avoid stressful activities .

If symptoms increase despite conservative treatment some form

of operative treatment may be needed such as jointdebridement: removal of interfering osteophytes and cartilagetags and loose bodies realignment osteotomy

- Late :

Surgical intervention :Total Knee Arthroplasty (TKA) :

The primary indication for TKA is to relieve pain caused bysevere arthritis .

~ Pain should be significant & disabling , especially during night.

dysfunction of the knee is causing significant reduction in theatient's ualit of life

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