Knee joint D.Rania Gabr D.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 Transverse condyles epicondyles intercondylar notch patella tibial tuberosity tibial plateaus

During the entire range of knee flexion, the patella only 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 Suprapatellar bursa: between femur & quadriceps tendon. 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. 1 2 5 3 4

The synovial membrane 1- lines the capsule, 2- communicates with: - suprapatellar bursa, - popliteus bursa, - semimembranosus burse - gastrocnemius bursa.

Ligaments: 4 Extracapsular 2 1 Ligamentum patellae (patellar ligament): from patella to tibial tuberosity. Oblique popliteal ligament: extension of semimembranosus tendon.

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 The 2 menisci (semilunar cartilages). Transverse ligament The cruciate ligaments. 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 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

2. Cruciate ligaments 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

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.

Anterior knee in extension Posterior knee in extension Vastus lateralis Vastus medialis extensor retinacula Patellar Ligament

Nerve supply of the knee joint: Femoral, obturator, tibial, and common pernoneal nerves. Arterial supply of From the anastomosis around knee.

Popliteal fossa Shape: Diamond-shaped region Site: 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 Semi- membranosus Biceps femoris Semi-tendinosus Gracilis Sartorius Plantaris Med. head of gastrocnemius Lat. head of gastrocnemius

Contents Popliteal fossa vessels Tibial nerve Short saphenous vein Common peroneal nerve

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