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Knee joint

Knee joint. It is a synovial joint of hinge variety. It is made by: The convex surface of femoral condyles The concave surface of tibial condyles The patella The fibula has nothing to do with the joint but is important for stability

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Knee joint

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  1. Knee joint • It is a synovial joint of hinge variety. • It is made by: The convex surface of femoral condyles The concave surface of tibial condyles The patella • The fibula has nothing to do with the joint but is important for stability • The articular surfaces are covered by hyaline cartilage • It unites the two longest levers in the body Femur Tibia

  2. Joint Capsule • Largest in body • Surrounds entire joint, except anteriorly • A nteriorly is replaced by quadriceps tendon, patella, and patellar ligament • It is pierce by the popliteus muscle tendon

  3. Synovial Membrane • It is intracapsular • Lines the capsule • Covers all intacapsular and extra articular surface of the joint • It also covers the cruciate ligaments • It bulges at the tendon insertions around the joint to form bursa • They minimize the friction of tendons during contraction

  4. Bursa • 20 + associated with the knee • Most important • Subcutaneous prepatellar • Subcutaneous infrapatellar • Deep infrapatellar • Anserine bursa • Bursa deep to iliotibial band • Inferior subtendinous bursa of biceps • Popliteal bursa • Semimemranosus bursa • Gastrocnemius bursa

  5. Extent of Capsule and Synovial membrane

  6. Extracapsular Ligaments Collateral Ligaments • Medial collateral ligament (MCL) flat band, attached above medial condyle of the femur and below to the medial surface of the shaft of the tibia – resists lateral displacement and it is weak • Lateral collateral ligament (LCL) cordlike, attached above the lateral condyle of femur and to head of the fibula below– resists medial displacement and it is strong

  7. Extracapsular Ligaments Cont., • Oblique popliteal derived from semimembranosus on posterior aspect of the capsule, runs from that tendon to medial aspect of the lateral femoral condyle (posteriorly) • Arcuate popliteal from head of fibula, runs over the popliteus muscle to attach into posterior joint capsule • Patellar Ligament From the lower border of patella to the tibial tuberosity Oblique Popliteal Ligament Arcuate Popliteal Ligament

  8. Intracapsular Ligaments Anterior Cruciate Ligament (ACL) • Arises from the anterior region of intercondylar area • Attached to medial side of lateral condyle • It is the weak one • It prevent hyper extension of the knee • It prevents posterior displacement of femur on tibia • It prevents anterior displacement of tibia on femur Posterior Cruciate Ligament (PCL) • Arises from the posterior region of intercondylararea • Attached to the popliteal fossa and lateral side of medial condyle • It is the strongest of the two • It prevents hyper flexion of the knee • It prevents anterior displacement of femur on tibia • It prevents posterior displacement of tibia on femur

  9. Functions of Cruciate Ligaments

  10. The Menisci The articulating surface of the tibia is covered by fibrocartilaginous menisci (Medial and Lateral) Medial Meniscus: • larger than the lateral one reflects the shape of medial tibialcondyle • Anterior and posterior horns • Attached to medial collateral ligament and basically immobile Lateral Meniscus: • Smaller than medial and tighter • Almost forms a complete circle • Anterior and posterior horns • NOT attached to lateral collateral ligament

  11. Menisci Cont., The following are involved in the attachment of the menisci to the tibial condyles • Transverse ligament anteriorly • The medial collateral ligament attaches to the medial meniscus • The tendon of semimembranosus sends fibers to the posterior edge of medial meniscus • The popliteus muscle sends fibers to the lateral meniscus • The meniscofemoral ligament extends from the lateral meniscus (post) to the inside of the medial condyle near the PCL • The coronary liagaments

  12. Functions of Menisci • They enhance the joint stability by deepening the contact surface • They help with shock absorption by transmitting ½ of weight bearing load in full extension and some in flexion as well • They protect the articular cartilage • They transmit the load across the surface of the joint, thus reducing the load per unit area on the tibio-femoral contact sites. • The contact area in the joint is reduced 50% when the menisci are absent

  13. Menisci Cont., • In hi load situations, 70% of the load is absorbed by the menisci, especially the lateral meniscus • The menisci assist in lubrication of the joint by acting as a space filling mechanism, more fluid is dispersed to the surface of tibia and femur • 20% increase in friction following meniscal removal

  14. Blood Supply of the Knee Joint • Femoral Descending genicular – articular and saphenous • Popliteal Superior medial genicular, middle genicular, inferior medial genicular, superior lateral and inferior lateral genicular • Tibial Anterior and posterior tibialrecurrents • Also, anastamosis from descending branch of lateral circumflex femoral aa • Middle genicular branch sends fibers inside the joint to supply cruciate ligament, synovial membrane and periphery of menisci

  15. Nerve Supply of the Knee Joint • According to Hilton Low, nerve supply to knee joint comes from the nerves supplying the muscles working on the knee joint. • Articular branches come from: Femoral anteriorly Tibial posteriorly Common fibular laterally Obturator and saphenous medially

  16. Movements about the knee joint • Flexion • Extension • Internal (inward) rotation • Anterior aspect of tibia rotates inward. • External (outward) rotation • Anterior aspect of tibia rotates outward.

  17. Movements of the Knee Joint Knee Extensors includes: • Rectus femoris (two joint muscle) • Vastusmedialis • Vastusintermedius • Vastuslateralis Knee flexors includes: • Biceps femoris (long & short) • Semimembranosus • Semitendinosus • Sartorius • Gracilis • Popliteus • Gastrocnemius Internal rotation about the knee • Popliteus • Semimembranosus • semitendinosus External rotation about the knee • biceps femoris

  18. Muscles of the Leg The muscles are divided into the following compartments • Anterior group : • Lateral group: • Posterior group

  19. Anterior group : Tibialis anterior: • Origin: lateral surface of tibia • Insertion: first metatarsal bone Extensor digitorumlongus: • Origin: front of fibula • Insertion: lateral four toes Extensor hallucis: • Origin: front of fibula • Insertion: big toe Peroneus tertius: • origin: front of fibula below • Insertion: fifth toe

  20. Lateral Group Peroneus longus: • Origin: lateral side of fibula • Insertion: Plantar surface of foot medially Peroneus brevis: • Origin: lateral side of fibula • Insertion: base of 5th meta tarsal bone • Action: Eversion of the foot • Nerve supply: superficial peroneal nerve

  21. Posterior Group Gastrocnemius: • It consists of two heads • Origin: from the lateral and medial femoral condyles Soleus: • Origin: back of tibia Plantaris: • Origin: Latera condyle of femur • All three muscles are inserted to calcaneum • Action: Plantar flextion of the foot • Nerve supply: Tibial nerve

  22. Posterior Group Cont., • Popliteus: • Origin: Lateral condyle of femur • Insertion: back of tibia above • Action: medial rotation help in unlock the knee • Flexor hallucisLongus • Origin: back of fibula • Insertion: base of big toe • Action: Dorsiflextionof the foot • Nerve supply: Tibial nerve

  23. Posterior Group Cont., Felxordigtorumlongus: • Origin: back of the tibia • Insertion: base of lateral four toes Tibialisposterior: • Origin: Back of tibia • Insertion:Base of metatarsal bones • Action of both muscles: Dorsiflextion of the foot • Nerve supply: Tibial nerve

  24. Tibialis Anterior Extensor Hallucis extensorDigitorum Tibialis Posterior Peroneus Longus Peroneus Brevis Flexor Digitorum Flexor Hallucis Soleus Plantaris Gastrocnemius L Gastrocnemius M

  25. Blood Supply of the leg • Popliteal artery is the continuation of femoral artery at adductor hiatus • Gives: Anterior tibial artery Posterior tibial which gives the peroneal artery

  26. Q angle • An angle found by drawing a line from ASIS to middle of patella and a second line from mid patella to tibialtuberosity • Represents efficiency of Quadreceps • Most efficient = 10 degree • Males range from 10-14 degree • Females from 15-17 degree • Represents the valgus stress acting on knee • Great than 17 called genu Valgum or knock knees • Very small angle causes gen varum

  27. Knee deformities Genu valgus Genu varus

  28. Applied anatomy • Fracture tibia (subcutaneous) x-rays

  29. Applied anatomy • Prone to injury (sports) • Med. Meniscus } • Med. Coll. Lig. }unhappy triad • Ant. Cruciate } • Swelling (synovial cavity and bursa) • Pre-patella bursitis (“housemaids knee”) • Osteoarthritis and knee replacement • Deformities • Valgus and varus • Recurrent dislocation of patella (females)

  30. Movement and stability • Movements are flexion & extension • Medial & lateral rotation (lock & unlock) • A stable joint due to strong muscles and ligaments

  31. Support of the Joint • Knee supports the weight of the body and transmits forces from the ground • Functional stability of the joint is derived from the passive restraint of the ligaments, the active support of muscles, the joint geometry, and the compressive forces pushing the bones together

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