Week 5: Knee Joint & Ligaments Flashcards
What is the classification of the knee joint, and what movements are available?
- Condylar – movement in two planes
- Flexion/extension and internal/external rotation (of flexed knee)
What are the components of the knee joint?
- Femoral condyles (medial & lateral) - convex
- Tibial condyles (medial & lateral) - convex
- Patella (patello-femoral joint)
What is the tibiofemoral joint?
Complex synovial condylar joint
What is the patellofemoral joint?
Synovial joint and is part of the knee joint complex
Where does the joint capsule of the knee attach?
Attaches around joint margins – but anteriorly is replaced by patellar ligament
Which plateau of the proximal tibia is bigger?
Medial - 50% bigger to accomodate bigger femoral condyle
What is the relationship of the fibrous capsule with the collateral ligaments?
- Medially – blends with medial collateral ligament
- Laterally – it is separate from the lateral collateral ligament
What is the patellar ligament?
Terminal part of the tendinous insertion of the quadriceps femoris muscle to the tibial tuberosity
Describe the attachment sites of the patellar ligament:
Strong flat band attached to the inferior border of the patella and is continuous over the front of the patella with the fibers of the quadriceps tendon to attach distally to the tibial tuberosity
What are the functions of the patella ligament?
- Attaches the quadriceps muscle group to the tibia
- Resists upwards displacement of the patella
Describe the location of the infrapatellar (Hoffa’s) fat pad:
- Fills the space between the patellar ligament and the anterior intercondylar area of the tibia
- Attachments to the patella tendon (proximally), patella (inferior pole) and
anterior horns of the meniscus
What is the function of the infrapatellar fat pad?
It acts a deformable space filler (can change shape, position, pressure and volume thought with movements of the knee joint), with a proposed biomechanical role
Is the infrapatellar fat pad an intra- or extra-capsular structure?
Intracapsular, but extrasynovial, its posterior surface is covered with synovial lining
What tissue are plicae made of?
Synovium (inward fold of the synovial membrane)
What structures does the infrapatellar plica attach to?
Deep surface of the infrapatellar fat pad, extending to the intracondylar notch
Discuss the role of the infrapatellar plica structures in producing knee pain:
- May be impinged or stretched within the knee joint - irritation of these structures gives rise to what is known as ‘Plica Syndrome’ –particularly the medial plica
The iliotibial band is comprised of the longitudinally directed fibres from which muscles?
Gluteus maximus and tensor fascia lata
Within what soft tissue structure is the iliotibial band found?
Fascia lata
Describe the attachments of the iliotibial band:
- It is a thickened portion of the fascia lata
- It attaches to the iliac crest and to the length of the linea aspera via the lateral intermuscular septum
- Distally it attaches into the antero-lateral part of the lateral tibial condyle
- Some fibres blend in to the knee joint capsule, some contribute to the lateral patellar retinaculum
Can the iliotibial band be stretched at the knee joint?
No. Due to its thickness, and attachment along the length of the femur, the iliotibial band
- The proximal portion of the iliotibial band may be stretched over the lateral aspect of the hip joint
What two muscles take attachment from the distal ½ of the lateral intermuscular septum?
Short head biceps femoris and vastus lateralis
What is the oblique popliteal ligament?
Fibrous expansion of the tendon of the semimembranosus muscle, provides posterior reinforcement to the capsule
What movement is the oblique popliteal ligament most likely to restrict?
Hyperextension
What structure does the tendon of popliteus pass under to insert on the lateral femoral condyle?
Lateral collateral ligament
Describe the location of the arcuate (popliteal) ligament:
Back of the head of the fibula, arches upward and medially over the tendon of the popliteus muscle to spread out over the posterior surface of the capsule
Describe the attachment sites of the longer superficial medial collateral ligament:
- Medial epicondyle of femur to medial epicondyle of tibia and medial surface of tibial shaft (it extends distally into the bursa of the pes anserinus)
- Anterior fibres are confluent with the medial patellar retinaculum
Does the medial collateral ligament blend with the knee joint capsule?
Yes
To what intra-articular structure do the deep fibres of the medial collateral ligament attach?
The outer periphery of the medial meniscus
Describe the attachment sites of the lateral collateral ligament:
Lateral condyle of femur to lateral surface of fibula head
Does the lateral collateral ligament blend with the knee joint capsule?
No, it is extracapsular
- The lateral collateral ligament is separated from the capsule by a fat pad, through which run some of the vessels and a nerve to the knee joint (the inferior lateral genicular nerve and vessels)
What tendon passes deep to the lateral collateral ligament?
Tendon of popliteus (intracapsular)
What is the function of the collateral ligaments?
- MCL opposes valgus forces
- LCL opposes varus forces
How could the integrity of the MCL be tested?
Place the knee in extension and apply an abduction force to the tibia - a positive test will result in gapping of the medial aspect of the knee joint and/or reproduction of pain
What type of ligaments are the cruciate ligaments?
Intra-capsular, but as they are wrapped in synovial membrane are described as being extra synovial
What are the attachments of the anterior cruciate ligament?
Rough non-articular area of bone in front of the tibia to the posterior part of the medial aspect of the lateral femoral condyle
From the tibia to the femur, describe the direction of fibre bundles of the ACL:
Anteromedial and posterolateral
- Run posteriorly and superiorly
What are the attachment sites of the posterior cruciate ligament?
From area of bone posterior to the intercondylar eminence of the tibia to the lateral side of the medial condyle of the femur
From the tibia to the femur, describe the direction of fibre bundles of the PCL:
Anterolateral and posteromedial
- Run superiorly and anteriorly
Describe the function of the cruciate ligaments:
- ACL prevents anterior displacement of the tibia and internal rotation of the tibia on the femur
- PCL prevents posterior displacement of the tibia on the femur
