Ligaments of the Knee Flashcards
What type of joint is the knee and what does it allow ?
diarthrodial (synovial) joint that allows simultaneous rotation and translation
Anterior Cruciate Ligament (ACL)
- primary fxn
- secondary fxn
- resists anterolateral displacement of the tibia on the femur
- resists varus displacement at 0 degrees of flexion
Posterior Cruciate Ligament (LCL)
- primary fxn
- secondary fxn
- resists posterior tibial displacement, esp at 90 degrees of flexion
- resists varus displacement at 0 degrees of flexion
Lateral Collateral Ligament (LCL)
- primary fxn
- secondary fxn
- resists various displacement at 30 degrees of flexion
2. resists posterolateral rotatory displacement with flexion that is less than approximately 50 degree
Popliteofibular Ligament/Posterior Lateral Corner (PLC)
- primary fxn
- secondary fxn
- Resists posterolateral rotation of the tibia on the femur
2. resists various angulation and posterior displacement of the tibia on the femur
Medial Collateral Ligament (MCL)
- primary fxn
- secondary fxn
- resists valgus angulation
2. works in concert with ACL to provide restraint to axial rotation
What are the Lateral Structures of the knee-Layer 1?
- illiotibial tract
2. biceps femoris
What are the Lateral Structures of the knee-between Layer 1 and 2?
common peroneal nerve
What are the Lateral Structures of the knee-Layer 2?
Patellar retinaculum
What are the Lateral Structures of the knee-Superficial Layer 3?
- LCL
- fabellofibular ligament
- ALL
What are the Lateral Structures of the knee-btw the Superficial and Deep Layer 3?
lateral geniculate artery
What are the Lateral Structures of the knee-Deep Layer 3?
- Arcuate Ligament
- Coronary Ligament
- Popliteus tendon
- popliteofibular ligament
- capsule
What are the Medial Structures of the knee- Layer 1?
- Sartorious
2. Fascia (patellar retinaculum)
What are the Medial Structures of the knee- btw Layer 1 and 2?
- gracilis
- semitendinosis
- saphenous nerve
What are the Medial Structures of the knee- Layer 2?
- Semimembranosus
- Superficial MCL
- MPFL
- Posterior Oblique Ligament
What is the function of the ACL?
prevent anterior translation of the tibia relative to the femur
ACL- Intra or extra synovial structure?
intrasynovial structure
ACL- Origin
- Lateral Femoral Condyle
2. PL bundle originates posterior and distal to AM bundle
ACL- Insertion
- Broad and irregualr
2. anterior and between the intercondylar eminences of the tibia
ACL- Structure
- 33mm x 11mm in size
- 2 Bundles
- Anteromedial bundle
- Posterolateral bundle
ACL AM Bundle- Structure
- fibers are parallel in extension
- fibers are externally rotates in flexion
- high in both flexion and extension
ACL PL bundle- Structure
- PL bundle prevents pivot shift
- prevents internal tibial rotation with knee near extension
- tight in extension, loose in flexion
ACL- blood supply
middle geniculate artery
ACL- innervation and fxn of innervation
- contains significant innervation by posterior articular branches of tibial n.
- contains mechanoreceptor (Ruffini, pacing, Golgi tendon organs, free-nerve endings)
fxn-
- proprioception
- modulation of quadriceps function
ACL- Composition
- 90% Type 1 Collagen
2. 10% Type 3 Collagen
ACL- Biomechanics Tensile Strength
- Native ACL?
- BPTB
- Quadrupled Hamstring
- 2000 N
- 3000 N
- 4000 N
ACL vs PCL Bundles
Tight in flexion
ACL- AM
PCL- AL
ACL vs Bundles
Tight In extension
ACL- PL
PCL- PM
PCL- function
- prevents posterior translation of the tibia relative to the femur
- PCL and PLC work in concert to resist posterior and translation and posterolateral rotatory instability
PCL- origin
medial femoral condyle
PCL- insertion
tibia sulcus
PCL- structure
- 38mm x 13 mm
2. 2 Bundles- AL and PM
PCL- AL bundle
- shorter, thicker and stronger
2. double bundle recon- tensioned in midflexion
PCL- PM bundle
- longer, thinner weaker
double bundle recon-tension in extension and high flexion-protects against hyperextension
PCL- what makes proximal border of femoral insertion
medial intercondylar ridge
PCL- what separates the AL from the PM bundle
medial bifurcate ridge
PCL- origin of meniscofemoral ligaments and their insertion
O: posterior horn lateral meniscus
I: substance of the PCL
what is the ligament of Humphrey?
- meniscofemoral ligaments
- anterior to PCL
what is the ligament of Wrisberg?
- meniscofemoral ligaments
- posterior to PCL
PCL- Blood supply
Middle Geniculate Artert
PCL- Biomechanics
25oo N (vs posterior translation)
LCL (also called fibular collateral ligament)- Fxn
- resists varus angulation
2. works in concert with MCL to provide restraint to axial rotation
LCL- origin
lateral femoral condyle posterior and superior to insertion of popliteus
LCL- Path
runs superficial to popliteus
LCL- Insertion
- on the fibula anterior to the popliteofibular ligament on the fibula
- capsule’s most distal extent is just posterior to the fibula
LCL- structure
cord like
LCL- biomechanics
- tight in extension and lax in flexion
- strength 750N (vs various stress)
Posterior Lateral Corner (PLC)- fxn
works synergistically with PCL to control external rotation and posterior translation
Posterior Lateral Corner- Included structures and Strength
- LCL (295 N)
- Popliteus Muscle and Tendon (680 N)
- Popliteofibular ligament (229N)
- Lateral Capsule
Posterior Lateral Corner - Variable Anatomy
- Arcuate Ligament
- iliotibial band
- fabellofibular ligament
MCL- Fxn
- resists valgus angulation
2. works in concert with ACL to provide restraint to axial rotation
MCL- Origin
MFC to medial tibia extending down several cm
MCL- structure
- has 2 components Superficial Portion (tibial collateral ligament) and deep portion (medial capsular ligament)
MCL- Superficial Portion (tibial collateral ligament)
- lies deep to gracilis and ST
- O- medical femoral epicondyle and I- periosteum of proximal tibia deep to pos anserinus
- contributes to 57% and 78% of medial stability at 5 deg and 25 deg of knee flexion respectively
- primary stabilizer to valgus stress at all angles
MCL- Deep Portion (medial capsular ligament)
- separated from superficial portion by a bursa
- attaches to medial meniscus (coronary ligament)
- divided into meniscofemoral and meniscotibial portions
- posterior fibers of the deep MCL blend with posteromedial capsule and POL
- deep MCL and posteromedial capsule act as secondary restraints to values stress at full knee extensions
MCL- biomechanics
4000 N (vs valgus stress)
Posterioromedial Corner- fxn
important for rotatory stability
Posterioromedial Corner- Lies deep to…
MCL
Posterioromedial Corner- formed by…
- Insertion of ST
- posterior oblique ligament-resists tibial internal rotation at full extension
- oblique popliteal ligament
- posterior capsule
Medical patellofemoral ligament (MPFL)- fxn
provide restraint against lateral translation of the patella from 0 to 30 of knee flexion
Medical patellofemoral ligament (MPFL)-characteristics
- low tension throughout flex-ex (2-10N)
- isometric btw 0 and 90 deg, then becomes slack beyond 90 deg
- can withstand 200N before tearing- much lower load to failure than ACL (1725N)
Medical patellofemoral ligament (MPFL)- Anatomy
- 2nd layer of medical soft tissue complex
2. 2 bundles - Short oblique bundle (insert on superior patellar pole) and inferior straight bundle
Medical patellofemoral ligament (MPFL)-femoral inserion
medial femoral condyle, distal to adductor tubercle and prox to MCL attachement
Medical patellofemoral ligament (MPFL)- Schottle’s Point
- 1.3mm anterior to posterior femoral diaphysial cortex
- 2.5mm distal to posterior origin of medial femoral condyle
- proximal to level of posterior point of Blumensaat’s line
Medical patellofemoral ligament (MPFL)- patellar attachment
- fan-like structure inserting at junction between proximal-middle thirds of superomedial border of patella
Medical patellofemoral ligament (MPFL)-pathoanatomy
- tears off femoral attachment > patellar attachement
2. res of 2nd dislocation is 13%- 3rd dislocation is 50%
Anterolateral Ligament-fxn
rotational stability
Anterolateral Ligament- anatomy
layer 3 with LCL
Anterolateral Ligament- Characteristics
- width 7mm at midpoint/near joint line
- femoral attachement Edith 8mm
- tibial attachment width 11mm - length 59mm
Anterolateral Ligament- Attachments
Femoral- Lateral Femoral epicondyle
Tibial- Midway between Gerdy’s and head of fibula
What is contained btw lateral meniscus and ALL at level of joint line
lateral inferior vehicular artery and vein
Anterolateral Ligament- Pathoanatomy
Segond Fracture (a/w ACL rupture) is avulsion fracture of ALL