1. Knee Joint

2. 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.

7. Anterior
Posterior
Transverse
condyles
epicondyles
intercondylar notch
patella
tibial tuberosity
tibial plateaus

8. Anterior. Patella articulates with the femur.
Sagittal section thru knee
Tibia:
Condyles (plateaus)
Tibial tuberosity
Tibia and fibula
are united by an
interosseous
Membrane.
[Proximal and
distal tibio-fibular
jts]
The fibula is not part of the knee joint.
Head of
Fibula
Patella articulates
with the femur.
interosseous membrane

9. During the entire
range of knee
flexion, the patella
only articulates
with the femur.
KNEE:
Modified hinge jt.
-flexion / extension
(some rotation)

10. Superior view of tibial surface.
Tibial Condyles
Tibial Condyles
Medial and lateral articular
surfaces, separated by an
intercondylar eminence.
Medial and lateral Menisci:
Fibrocartilage shock-absorbers
that sit on surface of tibial
condyles and deepen the
articular surface.
Anterior and posterior
Cruciate ligaments (ACL, PCL):
-hold femur and tibia together
-stabilize knee joint
lateral articular surface
medial articular surface
intercondylar eminence
lateral meniscus
PCL
medial meniscus
ACL

11. tibia at their ends (horns), and outer periphery (coronary lig.)
Medial and lateral
femoral condyles
have same shape as
corresponding
tibial condyles:
Medial – elongated
Lateral – circular
Meniscii:
Each is attached to
tibia at their ends (horns),
and outer periphery
(coronary lig.)
Femur

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

13. Capsule
Deficient anteriorly & is replaced by: quadriceps femoris tendon, patella & ligamentum patellae.
Possesses 2 openings: one (posteriorly) for popliteus tendon & one (anteriorly) for communication with suprapatellar bursa.

14. 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.

15. Lateral meniscus Medial
Size
small
Large
Shape
Circular
Oval
Outer 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

16. The synovial membrane 1- lines the capsule,
2- attaches to the margins of the articular surfaces,
3- attaches to the peripheral edges of the menisci (semilunar cartilages),
4- covers the front of the ant cruciate ligament, and the back of posterior cruciate ligament.
5- communicates with:
- suprapatellar bursa,
- popliteus bursa,
- semimembranosus burse,
- gastrocnemius bursa.

17. Bursae Related to Knee
Suprapatellar bursa: between femur & quadriceps tendon, communicates with synovial membrane of knee joint
Prepatellar bursa: between patella & skin.
Deep infrapatellar bursa: between tibia & ligamentum patella.
Subcutaneous infrapatellar bursa: between tibial tuberosity & skin.
Popliteal bursa: between popliteus tendon & capsule, communicates with synovial membrane of knee joint. 1 2 5 3 4

18. Working on hands-and-knees: Housemaid knee bursa
subcutaneus prepatellar bursitis.

19. Ligaments: 4 Extracapsular3 1 2
Ligamentum patellae (patellar ligament): from patella to tibial tuberosity.
Medial (tibial) collateral ligament: from medial epicondyle of femur to upper part of medial surface of tibia (firmly attached to medial meniscus).
Lateral (fibular) collateral ligament: from lateral epicondyle of femur to head of fibula (separated from lateral meniscus by popliteus tendon).
Oblique popliteal ligament: extension of semimembranosus tendon.

20. Ligaments: 2 Intracapsular The Cruciate Ligaments
Two in number, situated in the middle of the joint.
They are called cruciate because they cross each other
Have received the names anterior and posterior, from the position of their attachments to the tibia.

21. 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.
Prevents hyperextension.
Weaker of the two, slack when knee is flexed & tightens in extension.
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.

22. Stabilization of the medial knee: Tibial collateral ligament.
A flat strap which
is attached to the
medial aspect of
tibia and medial
femoral epicondyle.
Its deeper fibres are
attached to the
medial meniscus.
tibial collateral ligament
Joint capsule
Retinacular
fibres
Pes anserinus (goose’s foot): Common insertion of
Sartorius, gracilis, semitendinosus

23. Movements FLEXION: EXTENSION:
Mainly by hamstring muscles: biceps femoris , semitendinosus & semimembranosus.
Assisted by sartorius , gracilis & popliteus.
EXTENSION:
Quadriceps femoris.
ACTIVE ROTATION (PERFORMED WHEN KNEE IS FLEXED):
A) MEDIAL ROTATION:
Mainly by semitendinosus & semimembranosus.
Assisted by sartorius & gracilis.
B) LATERAL ROTATION:
Biceps femoris.

24. 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.
B) UNLOCKING OF KNEE:
Medial rotation of tibia, at the beginning of flexion.
Performed by popliteus to relax ligaments & allow easy flexion.

25. Anterior knee in extension
Fibrous capsule of the
KNEE (anterior):
Stabilized by:
Extensor Retinacula
- Derived from insertions
of vastus lateralis and
vastis medialis into patella
and into sides of patellar
ligament.
Vastus
lateralis
Vastus medialis
extensor retinacula
Patellar
Ligament

26. Posterior knee in extension
Fibrous capsule of the
KNEE (posterior):
Thickened by ligaments:
-Arcuate popliteal ligament
(arching over popliteus muscle)
-Oblique popliteal ligament
(from tendon of insertion of
semimembranosus m.)
arcuate politeal ligament
Tendon of
Semimembranosus
oblique popliteal ligament
Popliteus

27. Structures inside the Knee joint:
1- The 2 menisci (semilunar cartilages).
2- The cruciate ligaments.
3- Popliteus tendon.
Nerve supply of the
knee joint:
Femoral, obturator, tibial, and
common pernoneal nerves.
Arterial supply of
From the anastomosis around knee.

28. 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.

29. Atypical Q-angles
bowleggedness
knock-knees