The Knee Joint Flashcards
What are the bony surfaces of the knee joint?
Condylar of femur
Condylar of tibia
Patellar surface of femur
Atricular surface of patella
Describe the femoral condyles
Medial is larger than lateral- takes more weight Between the condyles
◦ Anteriorly- Shallow depression for patella articulation
◦ Posteriorly- Deep notch - Intercondylar fossa
Describe the tibial surface
Tibial plateau
Medial surface- slightly concave
Lateral surface- slightly convex
These are separated by intercondylar eminence
Describe the patella
Largest sesame id bone
Develops in a tendon
Provides mechanical advantage to quadriceps tendon
Why is the knee joint unstable and how is it stabilised?
Unstable as round surface articulating Ona flat surface
Deepen the articular surface of the Tibial element
◦ Menisci
Support the joint by various structures
◦ Ligaments
◦ Capsule
◦ Muscles
What are the menisci
Deepen the surface of articulation
Crescentic plates of fibrocartilage
Act as shock absorbers
Thicker at edges- Wedge shaped
Attached to intercondylar areas
Are attached to joint capsule via Coronary ligaments
Anteriorly connected by transverse ligament of the knee
What are the ligaments involved in the knee joint
Intra-capsular ◦ Cruciate ligaments Ligaments that strengthen the capsule ◦ Oblique popliteal ligament Extra-capsular ◦ Collateral ligaments Cruciate
Describe the cruciate ligaments
Posterior passes Anterior inserts Medially
Anterior passes Posterior inserts Laterally
ACL- weaker of the two
Relatively poor blood supply
Limits anterior movement of Tibia on Femur
PCL- stronger of the two
Limits posterior movement of tibia on femur
In weight bearing flexed knee- PCL is the main stabilizer
What is the joint capsule?
Surrounds sides and posterior aspect of joint
◦ Is absent anteriorly
◦ Allows synovial membrane to extend up beneath patella (supra-patellar bursa)
◦ Strengthened laterally
◦ Inferior fibres of Vastus lateralis/medialis
◦ Strengthened posteriorly
◦ Oblique popliteal ligament
◦ Expansion of semimembranosus
Communication anteriorly - joint capsule slightly deficient anteriorly
joint capsule strengthened laterrly
What are extra-capsular ligaments
Medial (Tibial) collateral ligament ◦ Medial Femoral epicondyle to Tibia Lateral collateral ligament ◦ Lateral Femoral epicondyle to lateral surface of Fibular head ◦ Also reinforced by Iliotibial tract
Where is th medial tibial collateral ligament attached?
Medial Tibial collateral ligament attaches to the Medial meniscus at its midpoint
◦ Clinically important
Give an overview of the movement of the knee
Flexion- Hamstrings (Gastrocnemius) Extension- Quads When knee is flexed you can get some rotation ◦ Medially- Semitendinosus ◦ Laterally- Biceps Femoris
Describe the stabilising effect of muscles
Most important is Quadriceps femoris
Especially inferior fibres of-
◦ Vastus Medialis ◦ Vastus Lateralis
Also the Iliotibial tract laterally
What is locking of the knee?
Most stable when locked
So it is less effort to stand
Femur rotates internally (over Tibia)
In this position the Knee joint can be held in position
To ‘unlock’ -Popliteus helps to rotate femur externally
What are bursae?
Synovial sacs - cushion the interface between tendons and bones
when inflamed - bursitis
Bursae
◦ 3 important ones
◦ Supra-patellar ◦ Pre-patellar ◦ Superficial Infra-patellar
