Lecture 15: Medial support complex Flashcards
what are the 3 layers of tissue in the medial support complex?
1: superficial
2: middle
3: deep
superficial layer of the medial support complex
- sartorius and fascia
middle layer of the medial support complex
contains superficial MCL and semimembranosus (which is part of the hamstrings)
what is apart of the deep layer of the medial support complex?
contains deep fibers of MCL and capsule
stability of the medial support complex
- MCL primary stabilizer 25-30 degrees of flexion
- muscles help in full extension
- medial hamstrings (Sartorius, semimembranosus + semintondosus )
- medial head of gastrocs
- quad muscles (vastus med)
- bony structure is tertiary support
Medial collateral ligament (MCL)
- a capsular ligament
- has superficial and deep components
- deep portions connect directly to the medial meniscus
- superficial portions run from medial femoral epicondyle to supermedial surface of tibia
what is swelling like in the Medial Collateral ligament (MCL)?
it is a capsular ligament therefore you will see big thick capsular swelling near 8hr afterwards
what are the second line of support for medial knee injuries?
the ACL and MCL
what are the cruciates of the knee?
1: the ACL
2: the PCL
where does the word “cruciates” come from?
means that the ligaments (ACL and PCL) cross
anatomy of the anterior cruciate ligament (ACL)
- it runs from anterior aspect of tibial plateau to the posterior medial aspect of lateral femoral condyle.
- primary restraint to anterior tibial translation
the greatest translation of the ACL occurs at
20-30 degrees
what are the 2 major bundles named for their attachment on the tibia of the ACL?
1: anteromedial - tighter in flexion
2: posterolateral - tighter in extension
ACL attachments
- from anterior aspect of the tibial plateau to posterior medial aspect of lateral femoral condyle
- 2 major bands:
1: anteriomedial
2: posterolateral
what is the stablizing role of the ACL
1: restrict posterior translation of the femur relative to the tibia during weight bearing (when it is fixed it stops the tibia from moving backwards)
2: restricts anterior translation of the tibia during non-weight bearing (stops it from moving forwards)
3: secondary support for VALGUS and VARUS with collateral ligament damage
anatomy of the posterior cruciate ligament (PCL)
- the PCL orginates on the lateral aspect of the medial femoral condyle and inserts posteriorly to intercondylar area of tibia
- larger and stronger than the ACL (so it doesn’t get injured as much)
- primary restraint to posterior tibial translation
what degree is the greatest translation that occurs at the posterior cruciate ligament (PCL)?
- 30 degrees
what are the 2 major bundles named for their attachment on the tibiafor PCL
1: anterolateral - tight in flexion
2: posteromedial - tight in extension
PCL attachments
- from lateral aspect of medial femoral condyle
- passes medial to ACL
- inserts posteriorly to intercondylar area of tibia
stabilizing role of the PCL
1: functions to restrict anterior translation of the femur relative to the tibia during weight bearing
2: restricts posterior translation of the tibia during non-weight bearing
3: limits hyper-internal rotation
the meniscus
- serve essential roles in maintaining knee function
- stabilize knee by increasing concavity of tibia (deepens the socket and allows for the tibia to sit in it)
- shock absorption
(full extension 45-50% of load)
(90 degree flexion 85% of load)
(compression facilitates distribution of nutrients)
medial meniscus
- C - shaped
- larger radius of curvature (bigger and rounder)
- tight connection with capsule and MCL
- poor mobility (basically means it is stuck there because it is less mobile it might be more likely to be torn)
lateral meniscus
- O shaped
- smaller (tighter) radius of curvature
- attached loosely to capsule and popliteal tendon
- increased mobility
what muscle do you use for the first couple of degrees of knee flexion getting out of screw home
popliteus
meniscal fixation
- significant disparity in the literature and between individuals
- the menisci are fixed in place and prevented from extruding by coronary ligaments and anterior and posterior transverse meniscal ligaments
- deep portion of capsule attached to periphery of meniscus
- medial is thicker/tighter than the lateral (this is why it is less mobile)
meniscal blood flow
- each meniscus can be divided into 3 different zones
1: red-red zone
2: red-white zone
3: White - white zone
red- red zone
- heals well because you are not cutting the meniscus and so it can heal nicely
- has good blood supply - outer 1/3
Red-white zone
- minimal blood flow supply
- middle 1/3
white- white zone
- is avasular
clinical perspective of knee injuries
pretty much just doing SOAP (same as usual)
area of pain in a knee assessment
1: medial: thinking ACL
2: lateral : thinking MCL
3: internal: thinking ACL PCL
subjective knee assessment
mechanism of injury
- varus or valgus
- contact or non-contact
sounds (i.e. pop or crack this is when you think its a fracture )
continue to play/able to WB?
locking, giving way since (this is when you are thinking ACL mostly but it can also be other ligaments)
swelling of knee injuries
nature of any swelling - hemarthrosis
- bleeding into the joint
- typically occurs more quickly than synovial effusion/capsular swelling
- noticeable swelling 2-6 hours post-injury
- >75% were ACL tears in adults
- patellar dislocation next most common (young)
- in paediatrics, suspect patellar dislocation
Ottawa knee rules
x-ray series is only required for knee injury patients with any of the below
1: age 55 or older
(because you are worried about their bone density)
2: isolated tenderness of the patella
3: tenderness of the head of the fibula
4: cannot flex 90 degrees
5: unable to bear weight both immediately and in the emergency room department for 4 steps
Acute patellar dislocation
MOI
- forceful knee rotation (tibia external rotation/ femur internal rotation) +- forceful quadriceps contraction
- knee usually near full extension (out of trochlea)
- +- laterally directed force
patellar dislocation - symptoms
- may report feeling knee “shift”, “move” or “pop out”
- pain ++ until reduced
- fast swelling (because you are tearing our a bunch of things)
patellar dislocation - signs
- loss of knee function (if still dislocated)
- tenderness over medial border of patella
- positive lateral apprehension text
what test do you do with a patellar dislocation
lateral apprehension test
3 layers of lateral support complex
1: superficial
2: middle
3: deep
superficial layer of lateral support
- iliotibial band and biceps femoris
middle layer of lateral support complex
- patellofemoral ligaments and retinaculum
deep layer of lateral support complex
- lateral (tibial) collateral ligament (LCL)
- popliteus tendon
- capsule
- other ligaments (Arcuate, Fabellofibular, etc)
Lateral Collateral Ligament (LCL)
- LCL injuries are less common but more complicated secondary to the number of structures
- usually varus loading +- hyperextension
- ## most contribution at 20-30 degrees of knee flexion
medial collateraal ligament - the facts
- 40% of all severe knee injuries involve the MCL , making it the most frequently injured knee structure
- valgus force with or without rotation
- often occur in isolation
signs and symptoms of collateral ligament sprains
swelling: timing
- minimal swelling LCL only - more if soft tissue is injured
- slow localized swelling medial side (grade 2+)
- capsular effusion > 8hrs
stress testing: in the same direction of MOI (done in 20-30 degrees because this is where you are looking for pain, laxity and endpoint)
- grade 1: pain with no laxity
- grade 2: pain with laxity. distinct end point
- grade 3: pain variable with gross laxity - no end point
valgus goes with —
varus going with —
1: MCL
2: LCL
ACL injuries
- occurs with either contact or non-contact (60-80%) mechanism
- usually during ocurring or single leg landing
- may occur in isolation or in combination with other injury
- 2-8 x higher injury rate in females
are ACL injuries more common in females or males?
females
what are the MOI of ACL injuries?
1: valgus after MCL - usually with contact
2: deceleration/internal rotation - non-contact
3: IT CAN NOT HAPPEN IN ISOLATION
4: quads active - anterior tibial translation
can ACL injuries occur in isolation?
NO
ACL injury: quads active mechanism
main mechanism
- rapid deceleration
- untoward landing
shoe - surface interface friction
anterior tibial dislocation by quads
ACL - key findings on subjective examination
symptoms
- 80% describe an audible “pop” or “crack”
- can range from very painful to minimal pain
- usually unable to continue activity
hemarthrosis
> 75% 1-6 hours
- may report instability or giving way
ACL objective findings (SIGNS)
signs
- restricted movement (especially extension)
lateral joint tenderness- often mistaken for LCL
- 80% lateral bone bruise or segond fracture
positive anterior drawer & lachmands positive
- graded like other ligaments
what is the best test to do for ACL injuries?
lockmans test
- looking for the end point
can also do anterior drawer but it is not truly the best
- it can be worse because the hamstrings might help and make things look different
posterior cruciate ligament injuries
- strongest of the knee ligaments
- only 1 in 10 cruciate injuries involve the PCL
- usually sports injuries - but also common in MVA’s
PCL Etiologogy/MOI
- most common is a direct blow to upper portion of the tibia
- fall on a flexed knee
- MVA -dashboard injury or pre-tibial trauma
hyper-flexion
- increase tension in anterior segment
- impinged between posterior tibia + inracondylar notch roof
hyperextension
PCL objective findings - signs
sings
- minimal swelling
- posterior drawer test is most sensitive
- graded like other ligaments
- sag test will be positive
- need to assess medial and lateral structures too!
patellofemoral pain
pain in the peripatellar/retropatellar area that is aggrevated by at least one activity that loads the patellofemoral joint during weight bearing on a flexed knee
- pain walking down stairs
- pain with squatting
- pain following sitting for long periods
- running, jumping, hopping
hypo pressure of the knee
the cartilage will degenerate from the inside out because it needs a certain amount of force to go through it to stay healthy
hyper pressure
is ruined because of grinding
propsed contributing INTRSINTIC factors
1: lower chain alignment
2: excessive pronation
3: poor multi-plane lumbo-pelvic/Pelvo femoral control (core, gluteus medius)
4: shortened muscles: hamstrings, ITB, calves and rectus femoris
5: pull of quads
the lower chain alignment (q-angle)
- if it is greater than 20 degrees it increases the risk of instability of PF joint
excessive pronation of the knee
- over pronation at the subtalar joint causes internal rotation of the tibia and delayed re-supination
- this affects screw-home mechanism as tibia does not externally rotate
- as such the femur must internally rotate more to get to extension
- results in lateral pull on the patella
poor multi-plane lumbo-pelvic/ pelvo femoral control (AKA medial collapse mechanism)
- hip adduction, femoral internal rotation and knee valgus
- change femur under patella
- decrease contact area
- increase joint stress
vastus medialis dysfunction
- sum of all 4 quads and tibial tendon are offset into valgus
- theory that weak VMO will not be able to maintain alignment
- slow
- weak
-altered line of pull
will cause abnormal pull on the patella.. overloading lateral side
how do you treat for patellofemoral pain treatments?
pretty much do the normal phases
1: inital phase- POLICE/PEACE & LOVE
2: repair phase
3: remodeling phase
