KNEE JOINT

Knee Joint (Hinge Joint)It is the largest & one of the most complex joint of

the body. It consists of 3 joints in single synovial cavity.

Bones involved: Femur, tibia & Patella1- Laterally- tibiofemoral joint, between the lateral

condyle of the femur, lateral meniscus & lateral condyle of the tibia (modified hinge)

2- Medially- 2nd tibiofemoral joint, between the medial condyle of the femur, medial meniscus & medial condyle of the tibia (modified hinge)

3- An intermediate patellofemoral joint- between the patella & patellar surface of the femur (planar joint)

Bones of the Knee

ARTICULATION

Above> Rounded condyles of femurBelow>Condyles of tibia & their

cartilaginous menisciFront>Articulation between lower end of

femur & patella.Articular surfaces of femur, tibia & patella

are covered with “Hyaline-Cartilage”

TYPE

Forms of 2 types of joint:

1-Synovial Hindge Joint: B/w Femur & Tibia.2-Synovial Plane Joint: B/w Patella &

Femur.

CAPSULE

Attached to margins of ariticular surfaces & surrounds the sides & posterior aspect of joint.

SUPRAPATELLAR BURSA: The capsule is absent at

the front allowing synovial membrane to pouch upward beneath the quadriceps tendon this is called Suprapatellar bursa.

Capsule

MUSCLES STRENGTHENING THE CAPSULEOn each sides of Patella, capsule is

strengthened by expansion from tendons of Vastus Lateralis &Medialis.

Behind the joint capsule is strengthened by expansion of Semimembrensus called Oblique- Popliteal -ligament.

An opening in capsule behind lateral tibial condyle permits tendon of popliteus to emerge.

LIGAMENTS

LIGAMENTS

EXTRACAPSULAR LIGAMENTS

INTRACAPSULARLIGAMENTS

EXTRACAPSULAR LIGAMENT(outside the capsule)

EXTRACAPSULAR LIGAMENTS

LIGAMNETUM -PATELA

LATERAL -COLLATERAL LIG

MEDIAL-COLLATERAL LIG

OBLIQUE-POPLITEAL

LIG

continuation…1-Ligamentum patella: Is a continuation of

central portion of common tendon of quadricep-femoris.

Attached ABOVE> to lower border of patella, BELOW>to tuberosity of tibia.

2-Lateral-collateral lig: Cord-like, attached above to the lateral condyle of femur & below to head of fibula. prevents the knee from various forces. This ligament can be injured by blows to the medial side of the knee. Does not occur frequently.

Pes Anserine

Continuation..

3-Medial collateral lig: Flat-band, attached ABOVE to medial condyle of femur & BELOW to medial surface of shaft of tibia. It is firmly attached to edges of medial-meniscus. Prevents the knee from valgus forces. Often injured by blows to the lateral side of the knee.

4-Oblique-popliteal lig:It is a tendons expansion derived from semimembrnosous.It strengthens the posterior aspect of capsule.

Posterior Capsule

http://www.sechrest.com/mmg/knee/mcl/cl-anat.gif

INTRACAPSULAR LIGAMENT(Inside the capsule)Consists of CRUCIATE LIGAMENTS i.e.Anterior cuciate ligament & Posterior cruciate

ligament. these are the strong intracapsular ligament that cross each other within the joint cavity.

Anterior-cruciate-lig: Is attached to anterior intercondylar area of tibia & passes upward,backward & laterally to be attached to posterior part of medial surface of lateral femoral condyle. In short>It attaches to the tibia anteriorly and the femur posteriorly.

Continuation…FUNCTION: when the knee joint if flexed it

prevents the tibia in moving forward or pulled anteriorly, posterior displacement of femur on tibia ,Helps maintain rotatory stability.

Posterior cruciate lig:Attached to posterior intercondylar area of tibia

& passes a upward, forward & medially to be attached anteriolaterally on medial condyle of femur. in short> It attaches anteriorly to the femur and posteriorly to the tibia. prevents the tibia from moving posteriorly.

KNEE LIGAMENTS AND CARTILAGE

MENISCIC-shaped sheets of fibrocartilage.the peripheralborder is thick & attached to capsule. inner borderis thin & concave & form free edges. upper

surfaceis in contact in condyles of femur& lower surface

incontact with condyles of tibia.Functions:

1. Stabilization2. Shock absorption3. Lubrication

MEDIAL MENISCUSBroader in front, most frequently injuredThe medial meniscus is “C” shaped.Attached to the medial collateral ligament.

Anterior

Posterior

MEDIAL MENISCUS

LATERAL MENISCUSThe lateral meniscus is “O” shaped.Not attached to the lateral collateral

ligament.

LATERAL MENISCUS

SYNOVIAL MEMBRANE

Lines the capsule & attached to margins of articular surfaces. On the front & above the joint forms Suprapatellar Bursa, it is held in position by attachment of Vastus intermedius called articularis Genus muscle. On back of joint Popliteal Bursa. A bursa interposed b/w medial head of gastrocnemius & medial condyle of femur & sememembrinosuos is Semimembrosus Bursa.

S.M is reflected forward from posterior part of capsule around the front of cruciate ligaments. as a result cruciate ligaments lie behind the syn.cavity & are not bathed in synovial fluid.

In anterior part of joint S.M is reflected backward from posterior surface of ligamentum patella to form Infrapatellar-Folds,the free borders of folds are termed as Alar –folds.

Menisci

Meniscal Attachments

BURSAE

Numerous bursae are reflected. They are found wherever skin, muscle or tendon rubs against bone.

4 are at front of joint & 6 are at behind the joint.

Suprapatellar bursae,popliteal bursa always communicate with joint &semimembrinosus bursa may communicate with joint.

CONTINUATION…

Anterior Bursae:

1-suprapatellar Bursae: Lies beneath quadriceps. communicate with

joint cavity. 2-Patellar Bursae: lies in subcutaneous tissues b/w skin & front of

lower half of patella & upper part of ligamentum patella. 3-Superficial infrapatellar Bursae: lies in subcutaneous tissues b/w

skin & front of lower part of ligamentum patella. 4-Deep infrepatellar Bursae: lies b/w ligamentum patella & tibia.

Bursa

CONTINUATION…

Posterior Bursae: 1-Popliteal Bursae: Found in association with tendon of popliteus &

communicate with joint cavity.

2-semimbranosus Bursae: Found related to insertion of

semimbranosus & may communicate with joint cavity.

Remaining 4 Bursae are found related to tendon of insertion of bicep femoris,tendonn of sartorius,gracilis & semitendonosus as they pass to their insertion on tibia,beneath lateral head of origin of gastrocenmius & beneath medial head of origin of gastrocnmius.

Nerve supply

FEMORAL NERVEOBTURATOR NERVETIBIAL NERVECOMMON PERONEAL NERVE

MOVEMENTS OF THE KNEE

FLEXION: performed by: bicep femoris, semimbranosus semitendonosus. Assisted by : Gracilis Sartorius Popliteus Flexion is limited by contact of back of leg with thigh. Extension: performed by: Quadricep femoris Limited by tension of all major ligaments of joint.

Knee Flexion

Knee Extension

CONTINUATION…

Medial rotation: performed by:SartoriusGracilisSemitendonosus

Lateral rotation:Performed by:Bicep femoris

RELATIONS

Anteriorly: Prepatellar BursaePosteriorly: popliteal vessels,tibial &

commonperoneal nerves,lymphnodes & muscles forming boundaries of popliteal fossa.

Medially:sartorius,Gracilis & semitendonsus.

Laterally: Bicep femoris,common peroneal nerve.

Patella

Patella