The Knee JointThe Knee JointTypeType: : Synovial, modified hingeSynovial, modified hinge

Articular surfacesArticular surfaces: : Lower end femur, upper end tibia, Lower end femur, upper end tibia, & posterior surface of the patella.& posterior surface of the patella.

Capsule and LigamentsCapsule and Ligaments::

The capsule is The capsule is thinthin::

1- 1- In frontIn front: It is absent : It is absent and replaced by and replaced by quadriceps tendon, quadriceps tendon, patella, and patella, and ligamentum patellae.ligamentum patellae.

22 - -BehindBehind: : the capsule the capsule is thinis thin,,

- -It is thickened by the It is thickened by the posterior posterior oblique ligament oblique ligament (strong (strong ligament, prevents ligament, prevents hyper extension hyper extension . .

- -It is perforated by the It is perforated by the popliteus muscle popliteus muscle..

Ligaments (outside the Ligaments (outside the joint)joint)::

11 - -The patellar lig. (ant)The patellar lig. (ant),,22 - -The posterior oblique The posterior oblique

lig lig..33 - -The lateral collateral The lateral collateral

liglig,.,.44 - -The medial collateral The medial collateral

liglig . .

The synovial membraneThe synovial membrane11 - -lines the capsulelines the capsule,,

22 - -attaches to the margins of attaches to the margins of the articular surfacesthe articular surfaces,,

33 - -attaches to the peripheral attaches to the peripheral edges of the menisci edges of the menisci (semilunar cartilages)(semilunar cartilages),,

44 - -covers the front of the ant. covers the front of the ant. cruciate ligament, and cruciate ligament, and the back of posterior the back of posterior cruciate ligamentcruciate ligament..

55 - -communicates withcommunicates with::

- - suprapatellar bursasuprapatellar bursa,,

- - popliteus bursapopliteus bursa,,

- - semimembranosus bursesemimembranosus burse,,

- - gastrocnemius bursagastrocnemius bursa..

Structures inside the knee jointStructures inside the knee joint::

11 - -The medial semilunar cartilage (Medial meniscus):The medial semilunar cartilage (Medial meniscus): C- C-shaped, fixed to the capsule of the knee joint and to the shaped, fixed to the capsule of the knee joint and to the medial collateral ligament (liable to injury), its ant. Horn is medial collateral ligament (liable to injury), its ant. Horn is attached to the most ant. part of the intercondylar area of the attached to the most ant. part of the intercondylar area of the upper end tibia and connected to the lat. semilunar cartilage by upper end tibia and connected to the lat. semilunar cartilage by the transverse ligthe transverse lig . .

22 - -The lateral semilunar cartilage (lat. Meniscus):The lateral semilunar cartilage (lat. Meniscus): Circular in Circular in shape, more mobile (separated from capsule and lat. shape, more mobile (separated from capsule and lat. collateral lig. by popliteus tendon, so it is more adaptive to collateral lig. by popliteus tendon, so it is more adaptive to

twisting movement and less liable to injurytwisting movement and less liable to injury . .

Structures inside the knee joint Structures inside the knee joint (cont.)(cont.)

33 - -Anterior cruciate ligamentAnterior cruciate ligament:: - -From ant. intercondylar area of tibia -- From ant. intercondylar area of tibia --

upward, backward and laterally upward, backward and laterally to the lat. condyle of the femurto the lat. condyle of the femur . .

- -It is relaxed in knee flexion, tense in It is relaxed in knee flexion, tense in extension so it prevents hyper- extension so it prevents hyper- extensionextension..

44 - -Posterior cruciate Posterior cruciate ligamentligament::

- -From post. Intercondylar area of tibia From post. Intercondylar area of tibia upwards, forward and medially to upwards, forward and medially to ant. part of medial femoral condyleant. part of medial femoral condyle..

- -It is relaxed in extension, tense in It is relaxed in extension, tense in flexion so it prevents hyperflexion and flexion so it prevents hyperflexion and anterior femoral dislocationanterior femoral dislocation..

Movements of the knee jointMovements of the knee joint::

1- 1- FlexionFlexion: : By the Hamstring muscles + By the Hamstring muscles + gracilis, gracilis, gastrocnemius, sartorius, popliteus, plantarisgastrocnemius, sartorius, popliteus, plantaris

22 - -ExtensionExtension: : By the Quadriceps femoris + By the Quadriceps femoris + tensor fascia tensor fascia lataelatae..

3- 3- Locking of the knee jointLocking of the knee joint = = medial rotation of the medial rotation of the femur on the tibia in full extension (or lateral femur on the tibia in full extension (or lateral rotation of the tibia) . It occurs by Biceps femoris.rotation of the tibia) . It occurs by Biceps femoris.

4- 4- Unlocking of the KneeUnlocking of the Knee: : In standing (tibia fixed) = In standing (tibia fixed) = lateral rotation of femur on tibia, In supine or lateral rotation of femur on tibia, In supine or sitting (tibia free) = Medial rotation of tibia. By sitting (tibia free) = Medial rotation of tibia. By popliteus + popliteus + sartorius, gracilis, semitendinosus and sartorius, gracilis, semitendinosus and semimembrenosussemimembrenosus..

Relations of the knee jointRelations of the knee joint::

Bursae related to the knee jointBursae related to the knee joint::11 - -Anterior to the kneeAnterior to the knee::

11 . .supra-patellar bursasupra-patellar bursa 22 . .prepatellar bursaprepatellar bursa

33 . .superficial infra-patellar bursasuperficial infra-patellar bursa 44 . .deep infrapatellar bursadeep infrapatellar bursa

22 - -Posterior to the kneePosterior to the knee:: 11 . .popliteus bursapopliteus bursa

22 . .semimembrenosus bursasemimembrenosus bursa 33 . .semitendinosus bursasemitendinosus bursa

44 . .gastrocnemius bursagastrocnemius bursa 55 . .gracilis bursagracilis bursa

66 . .biceps bursabiceps bursa 77 . .sartorius bursasartorius bursa

Structures inside the Knee jointStructures inside the Knee joint::1- the 2 menisci (semilunar 1- the 2 menisci (semilunar

cartilages).cartilages).22 - -The cruciate ligamentsThe cruciate ligaments..

33 - -Popliteus tendonPopliteus tendon..

Nerve supply of theNerve supply of the knee jointknee joint::Femoral, obturator, tibial, andFemoral, obturator, tibial, and common pernoneal nervescommon pernoneal nerves..

Arterial supply ofArterial supply of knee jointknee joint::

From the anastomosis around From the anastomosis around kneeknee..

Arterial supply of the kneeArterial supply of the knee::

Imaging of the knee jointImaging of the knee joint::

A- Plain X- RayA- Plain X- Ray

AP viewAP view . .

B- X- Ray of PatellaB- X- Ray of Patella

( ( knee flexedknee flexed.).)

C- Transverse MRIC- Transverse MRI

Showing the patelloShowing the patello--

femoral jointfemoral joint..

Radiograph of the knee joint (cont.)Radiograph of the knee joint (cont.)::

Imaging of the knee joint (cont.)Imaging of the knee joint (cont.)::

A. Coronal section throughA. Coronal section through

intercondylar notch ofintercondylar notch of

femur, and tibiafemur, and tibia..

B. MRI through same levelB. MRI through same level..

C. MRI through femoral andC. MRI through femoral and

tibial condylestibial condyles..