Download The knee

The knee
Lecture 8
Knee joint
The knee joint is the largest synovial
joint in the body.
It consists of:
a)
the articulation between the femur
and tibia, which is weight bearing;
b) the articulation between the
patella and the femur,
The femur
The distal end of femur is characterized by two large condyles, which
articulate with the proximal head of the tibia. The condyles are separated
posteriorly by an intercondylar fossa and are joined anteriorlly where they
articulate with the patella.
There are bony elevations on the nonarticular outer surfaces of the
condyles - lateral and medial epicondiles, which serve for attachment of
collateral ligaments of the knee joint.
Proximal end of tibia
The proximal end of the tibia is
expanded in the transverse plane for
weight bearing.
consists of:
1- medial condyle
2- lateral condyle.
Tibial plateau is the articular
surface of proximal tibia which has
2 articular fossa and intercondylar
eminence that has medial and lateral
intercondylar tubercles.
Inferior to the condyles on the
proximal part of the shaft is a large
tibial tuberosity and roughened area
for muscle and ligament attachment.
On the posterior surface of it is a
soleal line.
Proximal end of the
fibula
The fibula is the lateral bone of
the leg and does not take part in
formation of the knee joint or in
weightbearing.
It is much smaller than the tibia
and has a small proximal head, a
narrow neck, and shaft, which ends
as the lateral malleolus at the ankle.
1. Head
2. Neck
3. Shaft
Patella
The patella (knee cap) is the largest sesamoid bone in the body and is formed
within the tendon of the quadriceps femoris muscle.
The patella is triangular:
• its apex is pointed inferiorly for attachment to the patellar ligament, which
connects the patella to the tibia;
• its base is broad and thick for the attachment of the quadriceps femoris
muscle from above;
• its posterior surface articulates with the femur and has medial and lateral
facets for articulation.
Articular surfaces
The articular surfaces of the bones
that contribute to the knee joint are
covered by hyaline cartilage.
The major surfaces involved
include:
• the two femoral condyles;
• the adjacent surfaces of the superior
aspect of the tibial condyles.
The articular surfaces between the
femur and patella are the V-shaped
trench on the anterior surface of the
distal end of the femur.
Menisci
There are two menisci, which are
C-shaped cartilages, in the knee joint,
one medial (medial meniscus) and the
other lateral (lateral meniscus).
Both are attached at each end to
facets in the intercondylar region of the
tibial plateau.
The menisci are interconnected
anteriorly by a transverse ligament of
the knee.
The lateral meniscus is also
connected to the tendon of the popliteus
muscle, which pass between this
meniscus and the capsule to insert on
the femur.
Synovial membrane
The synovial membrane of the knee joint attaches to the margins of
the articular surfaces and to the superior and inferior outer margins of the
menisci.
The two cruciate ligaments, which attach in the intercondylar region
or eminence of the tibia below and the intercondylar fossa of the femur
above are outside the articular cavity, but enclosed within the fibrous
membrane of the knee joint.
Cruciate ligaments
The two cruciate ligaments are termed 'cruciate' because they cross each other in
the sagittal plane between their femoral and tibial attachments:
1. the anterior cruciate ligament attaches to a facet on the anterior part of the
intercondylar area of the tibia and ascends posteriorly to attach to a facet at the
back of the lateral wall of the intercondylar fossa of the femur;
2.
the posterior cruciate ligament attaches to the posterior aspect of the
intercondylar area of the tibia and ascends anteriorly to attach to the medial
wall of the intercondylar fossa of the femur.
knee joint bursas
The synovial membrane of the knee joint forms sacs in two locations to
provide low friction surfaces:
1. subpopliteal recess (lies between the lateral meniscus and the tendon of the
popliteus muscle);
2. suprapatellar bursa (between the distal end of the shaft of femur and the
quadriceps femoris muscle).
Other bursae include:
• subcutanous prepatellar bursa;
• deep infra-patellar bursae;
• subcutaneous or superficial infra-patellar bursae;
• and numerous other bursae associated with tendons and ligaments around
the joint.
َ
recess : ‫طـيـّة‬
Fibrous membrane
The fibrous membrane of the knee
joint is extensive , partly formed and
reinforced by ligaments and extensions
from tendons of the surrounding
muscles.
• on the medial side of the knee
joint, the fibrous membrane blends with
the tibial collateral ligament and is
attached to the medial meniscus;
• laterally, the external surface of the
fibrous membrane is separated by a
space from the fibular collateral
ligament and the internal surface of the
fibrous membrane is not attached to the
lateral meniscus.
Fibrous membrane
• anteriorly, the fibrous membrane is attached to the margins of the patella
where it is reinforced with the vastus lateralis, vastus medialis ,the quadriceps
femoris tendons and patellar ligament.
• Posteromedially, the fibrous membrane is reinforced by semimembranosus
tendon and the oblique popliteal ligament.
Ligaments of the knee
1. Patellar ligament
It is basically the continuation of the
quadriceps femoris tendon inferior to the
patella. It is attached above to the margins
and apex of the patella and below to the
tibial tuberosity.
2. Collateral ligaments:
a) fibular collateral ligament (lateral
femoral epicondyle -fibular head);
b) tibial collateral ligament (medial
femoral epicondyle -medial margin and
medial surface of the tibia).
The collateral ligaments, one on each side of
the joint, stabilize the hinge-like motion of
the knee