Knee joint

D.Rania GabrD.Sama.D.Elsherbiny

Objectives

Name and identify the bony features of the tibia and fibula.

Know the type and formation of knee joint.

Explain the stability factors of the knee joint.

Identify the muscles that act at the knee joint.

Know the locking and unlocking mechanism of the knee joint.

Understand the functions of the Popliteus and Iliotiabial tract.

Anterior Posterior AnteriorTransverse

condylesepicondyles

intercondylar notch

patella

tibial tuberosity

tibial plateaus

During the entirerange of kneeflexion, the patellaonly articulates with the femur.

Type & Articular Surfaces

Type: synovial Modified hinge Knee joint is formed of:Three bones.Femoro-tibial articulation: between the 2 femoral condyles & 2 tibial condyles (Type: synovial, modified hinge).Femoro-patellar articulation: between posterior surface of patella & patellar surface of femur (Type: synovial, plane).

Capsule

Deficient anteriorly & is replaced by: quadriceps femoris tendon, patella & ligamentum patellae.

Bursae Related to Knee

1. Suprapatellar bursa: between femur & quadriceps tendon.

2. Prepatellar bursa: between patella & skin.

3. Deep infrapatellar bursa: between tibia & ligamentum patella.

4. Subcutaneous infrapatellar bursa: between tibial tuberosity & skin.

5. Popliteal bursa: between popliteus tendon & capsule.

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The synovial membrane

1- lines the capsule,

2- communicates with:

- suprapatellar bursa,

- popliteus bursa,

- semimembranosus burse

- gastrocnemius bursa.

Ligaments: 4 Extracapsular

1. Ligamentum patellae (patellar ligament): from patella to tibial tuberosity.

2. Oblique popliteal ligament: extension of semimembranosus tendon.

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3. Medial (tibial) collateral ligament: from medial epicondyle of femur to upper part of medial surface of tibia (firmly attached to medial meniscus) and more liable to injury.

4. Lateral (fibular) collateral ligament: from lateral epicondyle of femur to head of fibula (separated from lateral meniscus by popliteus tendon).

Structures inside knee joint

1. The 2 menisci (semilunar cartilages).2. Transverse ligament3. The cruciate ligaments.4. Popliteus tendon.

1. Menisci

They are 2 C-shaped plates of fibro-cartilage attached by anterior & posterior horns, to the articular surface of tibia.

FUNCTION: Deepen articular surfaces of tibial condyles. Serve as cushions between tibia & femur.

Lateral meniscus

Medial meniscus

Size small LargeShape Circular OvalOuter border separated from lateral

collateral ligament by popliteal tendon.

attached to the capsule & medial collateral ligament.

Mobility More mobile Less mobile Liablity for injury

Less liable More liable

a. Anterior cruciate ligament:• Extends from anterior part of

intercondylar area of tibia to posterior part of lateral condyle of femur.

• Prevents posterior displacement of femur on tibia.

• It becomes tense during extension of the knee joint.

• Prevents hyperextension.• More liable to injury

2. Cruciate ligaments

b. Posterior cruciate ligament: • Extends from posterior part of

intercondylar area of tibia to anterior part of medial condyle of femur.

• Tightens during flexion of knee joint

• Prevents anterior displacement of femur on tibia.

Movements FLEXION:

SGSS. popliteus

EXTENSION: Quadriceps femoris and iliotibial tract

ACTIVE ROTATION (PERFORMED WHEN KNEE IS FLEXED):

A) MEDIAL ROTATION: SGSS

B) LATERAL ROTATION: Biceps femoris.

Movements

INACTIVE (DEPENDANT) ROTATION:

A) LOCKING OF KNEE: Lateral rotation of tibia, at the end of extension Results mainly by tension of anterior cruciate

ligament. In locked knee, all ligaments become tight. This is done by the action of: Biceps Femoris.

B) UNLOCKING OF KNEE: Medial rotation of tibia, at the beginning of

flexion. Performed by popliteus to relax ligaments & allow

easy flexion and helped by SGS.

extensor retinacula

Vastuslateralis

Vastus medialis

Anterior knee in extension

PatellarLigament

Posterior knee in extension

Nerve supply of the knee joint:Femoral, obturator, tibial,

and common pernoneal nerves.

Arterial supply of knee joint:From the anastomosis

around knee.

Shape: Diamond-shaped regionSite: Posterior to knee

Boundaries: upper medial: SGSS(sartouries-gracilis-

semimembranosus / semitendinosus upper lateral: biceps femoris lower medial; medial head of

gastrocnemius. lower lateral: lateral heads of gastrocnemius and plantaries. Superficial: Small saphenous vein draining into popliteal vein

Contents: popliteal vessels Tibial and Common fibular (peroneal) divisions of the sciatic nerve. Popliteal L.N

Popliteal fossa

Popliteal fossa

Lat. head ofgastrocnemius

Med. head ofgastrocnemius

Plantaris

Biceps femoris

Semi-membranosus

Semi-tendinosus

Gracilis

Sartorius

Shortsaphenous

vein Common peroneal

nerve

Tibial nerve

Poplitealvessels

Contents Popliteal fossa

Q-Angle

The Q-angle is the angle formed by :

1-a line from the anterior superior iliac spine to the middle of the patella ,and

2-a line from the middle of the patella to the tibial tuberosity.

Males typically have Q-angles between 10 to 14o,

females between 15-17o.

Atypical Q-angles

bowleggedness

knock-knees