Knee Injuries Flashcards
the anterior cruciate ligament attaches from the
anterior medial tibial plafond and to the medial aspect of the lateral femoral condyle
knee injuries commonly involve what
the medial meniscus, tibial collateral ligament/ anterior cruciate ligament (Lachman test, drawer sign, aspiration, arthroscopy)
what are popliteal cysts (Baker’s cysts)
are outpocketings of the synovial membrane of the knee joint
what is the function of the anterior cruciate ligament
limits anterior tibial displacements
- limits some internal rotation
- varus/valgus angulation in FULL EXTENSION
The ligaments ACL and PCL attach the — to the — to create a hinge joint called the knee
femur
tibia
what are the anterior and posterior cruciate ligaments
are 2 short, strong ligaments which criss-cross each other in the middle of the joint
ACL injuries are common in what sports
- football, basketball, soccer, gymnastics, volleyball, skiing
- more common in female than male soccer and basketball players
- primarily teens and early 20s
what is the mechanism of ACL injury
-cutting-deceleration-hyperextension
-most are non-contact
-60% have meniscal injury and medial collateral ligament injury
50% have subchondral bone injury –> DJD
what history is common with an ACL injury
-effusion and tenderness near patellar tenon/anterior tibial plateau
how do you measure stability of the ACL
measure the amount of excursion at end point
what other test should be performed for an ACL injury
- x-rays for avulsion fracture
- arthrogram
- MRI
- arthroscopy
how do you perform the drawer test
- patient supine and knee at 90 degrees flexion
- stabilize the proximal and distal segment
- grab the leg at the proximal tibia and pull towards you
why are 50% of drawer test a false negative
bc there may already be edema
how do you perform the Lachmann test
- patient supine and knee at 15 degrees flexion
- stabilize the proximal and distal segment
- grab the leg at the proximal tibia and pull toward you
- can standardize with a machine to measure displacement
what is a normal value for a KT-1000 test
> 3mm?
what % of Lachmann test are false positives
5-10%
what are the complications of ACL injury
- DJD associated with meniscal injury or avulsion
- instability increases likelihood of re-injury
- surgical intervention means long rehab
function of the posterior cruciate ligament
- limits posterior motion
- restricts external rotation
- keeps the tibia from moving too far posterior in relation to the femur (if the tibia moves too far posterior, the PCL can tear)
what is the # 1 cause of PCL injuries
auto accidents (right foot on break prior to impact)
what are other etiologies of PCL injuries
-sports due to direct blow to proximal tibia or hyperextension
what history is evident of PCL injury
“Pop” or no “pop”
No edema until 48 hrs
May bear weight
Reluctant to extend knee
what is seen upon examination of a PCL injury
- effusion variable bc of posterior muscle belly
- popliteal tenderness
- stability (much more stable than ACL injury)
- Sag test
- posterior drawer
what technique is used to test the posterior cruciate ligament
Sag test
how is the Sag test performed
- patient is supine as if sitting in a horizontal chair
- thighs at 90 degrees
- knees at 90 degrees
- examiner supports the legs by holding ankles and observes the sag as the tibial plateau sinks below patella
how is the posterior drawer and sag test performed
- patient supine and knee at 90 degree flexion
- stabilize the proximal and distal segment
- grab the leg at the proximal tibia and push away from you (tibia will move posterior)
- Sag test will be positive when you line up the knees even with each other, the injured side’s tibial tuberosity will not be even
what other diagnostic tools can be used to rest for PCL injury
x-ray for avulsion
MRI less accurate than ACL
arthroscopy (best diagnostic tool)
Fanelli, reports that the key to successful PCL reconstruction requires that the surgeon does what
- identifies and treats all pathology
- use of strong replacement grafts and materials is crucial
what is the medial collateral ligament
- deep layer is thickened capsule
- major medial stabilizer
what is O’Donahue’s Triad
- ACL
- MCL
- Medial Meniscus
MCL injuries are common in what sports
football and skiing
all MCL injuries involve what
- a blow laterally (except skiing, skating, etc.)
- very painful increasing over time
what history is common of a MCL injury
- struck from lateral side (football, soccer) or lateral to medial forces
- feels/hears a “pop”
- knee “stiffens up” within hrs
are partial or complete MCL tears more painful
partial (if all fibers are gone there is no pain)
what is evident upon examination of a MCL injury
- medial edema/minimal effusion
- medial ecchymosis if > 24 hrs old
- medial instability when stressed at 20 degree felxion
what is grade 1 MCL injury
no opening of medial joint
what is grade II of MCL injury
opens with firm end point
what is grade III of MCL injury
opens with soft end point
what test is performed for an MCL injury
varus/valgus stress test
how is a varus/valgus stress test performed
pt laying in supine position, hold ankle, apply force laterally to see if there is motion at the joint, then come around and apply force to the other side of the knee and apply medial force (valgus)
what are differential diagnosis of MCL injury
epiphyseal fracture (peds).
what is positive instability
- more pain with MCL injury
- not seen on x-ray
what does the MCL connect
-the end of the femur to the top of the tibia
what is the function of the medial collateral ligament
provides stability against valgus stress
a valgus stres is described as what
- a pressure applied to the leg that tries to bend the lower leg sideways at the knee, away from the other leg
what are common causes of MCL injury
-tackling in football or soccer
how do you treat grade I and II MCL injury
knee brace hinged with a locked position
how do you grade III MCL injury
cast immobilization of primary repair
Lateral collateral ligament results from
- major trauma w/ knee dislocation
- major vascular injury
- cruciates and common peroneal nerve is also damaged
describe the meniscus
- fibrocartilage (poor blood supply–> does not heal well)
- blood supply only to peripheral 1/3
- degenerates over time secondary to mechanics wear and tear
what is the primary function of the meniscus
- to redistribute pressure
- @ birth meniscus separates femur and tibia
how do meniscal injuries occur
-mostly a weight bearing injury
how do medial meniscal injuries occur
involves “cutting” (ie. football, soccer, basketball)
how to lateral meniscal injuries occur
rotation while squatting (ie. wrestling)
bucket handle tears are more common on what side
medial
bucket handle tears are prone to what
locking
bucket handle tears are common in who
younger athletes
what are flap tears
- may start as bucket handle
- impingement but not locking
what history is common in meniscal injuries
- specific injury with a “snap or pop”
- may lock right away (big trouble if this happens)
degenerative meniscal tears are common in who
-older athlete (>40 y/o)
degenerative meniscal tears are common with what type of trauma
minimal trauma
what features are characteristic of degenerative meniscal tears
- joint pain with activity
- recurrent effusions
- minimal impingement episodes
- can’t squat
what do you examine for in a meniscal injury
- medial joint line
- lateral joint line
- meniscal impingement test
what is the McMurray test
a provocative meniscal impingement test
how is McMurray Test performed
- from supine position
- knee flexed to 90’ externally rotated
- extend leg on thigh with varus stress while palpating medial joint line
- pain with audible/palpable click
what is Apley compression test
a provocative meniscal impingement test
how is Apley Compression performed
- from prone position
- knee flexed 90 degrees
- compress leg toward knee while rotating foot externally
- pain elicited is positive
what is the purpose of provocative tests
- designed to entrap/lock torn fragment
- requires full flexion
- impossible in presence of effusion
- all are very painful (don’t give anaesthesia)
what is the gold standard for meniscal imaging
arthrogram
what is the new gold standard for meniscal imaging
MR
1/3 of adults have tears that are nonsymptomatic
where is the patella located
within the conjoined tendon
the patella has a tendency to displace —
laterally
what restricts lateral movement of the patella
femoral trochlea
what are the first time dislocation patellar displacement
- medial retinacular tears
- vastus medialis tears
- fractured patella
what history is common with patella dislocation
- knee flexed 20-40 degrees with quadriceps contracting
- foot is externally rotated (cutting)
- “ripping tearing grinding”
- immediate disability
- patient will describe watching the knee enlarge-immediate effusion
- patient usually unaware to what happened
patellar displacement usually from
intrinsic forces
why may the patella fail to reduce with extension
may be blocked with a fragment - DO NOT FORCE IT
what is Fulkerson Classification
type I - subluxation alone
type II - subluxation and tilt
type III - tilt alone
type IV - no malalignment
how do you treat patella injury
- immobilization to 10 degrees flexion
- PRICE
- after 48 hrs remove immobilizer to being ROM exercise
- isometric Quads contraction ASAP
- E-stim over Vastus Medialis 2 hrs every day
- once motion returns D/C brace for patellar stabilizer 3-6 months
what is Patella Femoral Dysfunction (PFD)
Patellalgia Anterior knee pain Chrondromalacia Patella Patellar compression syndrome One of the most common complaints (11.3%) 25% of all athletes Females >> Males
how does the biomechanics of the patella change with activity and position
Walking = .5 X BW (5 degrees = 30%) Stairs = 3.3 X BW (30 degrees = 2X, 45 degrees = 3X) Squatting = 6 X BW (75 degrees)
what are the different grades of Chrondromalacia patella
I – Softening/ Degeneration of Articular Cartilage
II – Cleaving of AC
III – Cleaving and Fronds of AC
IV – Wearing away of AC to Subchondral bone
what are the biomechanics of the patella
Trochlea engaged at 20 – 30 degrees flexion
Increases knee extension force by 50%
what is the Q-angle
is the angle formed by a line drawn from the ASIS to central patella and a second linedrawn from central patella to tibial tubercle
what can cause patella femoral dysfunction/patella alignment
- weak vastus medialis
- pronation
patella femoral dysfunction is associated with what foot types
- partially compensated FF varus
- compensated FF varus
- flexible FF valgus
- compensated congenital gastrocnemius equinus
- compensated trasnverse plane deformity
what is the normal femoral anteversion
18’
If >20 degrees pain, OA, PFD
what is plica
- redundant fold in synovial lining of knee
- tears at femoral condyles
- “movie sign” - if you sit in a movie theatre for too long you have knee pain and have to get up and move around
what must you note during examination of PFD***
Patella Acta (high) Patella Baja (low) Squinting (like knock knees) Frog Eye (if up and out) Note tracking during gait Patella Apprehension Test (will hurt even if ok -> depends on extent of pain) provocative test (don’t forget referred pain from hip)
what test is positive with plica
theatre sign
what is a common H&P of plica
- gradual onset
- if fibrosed it can “pop” during extension
- will cause buckling if entrapped
- see tight hamstrings and weak quads
iliotibial band syndrome is associated with what
tight IT band
what can cause iliotibial band syndrome
- genu varum or Runner’s varum (narrower base of gait when running)
- IT bands gets irritated as it pops back and forth over the femoral epicondyle
where does Iliotibial band syndrome cause pain
lateral knee pain
what test is positive in iliotibial band syndrome
ober’s test
what is evident during PE of patellar dislocation
- large, tense painful effusion
- pain at retinaculum, vastus medialis
- can not extend knee past 10-15 degrees
- medial ecchymosis 12-18 hrs
according to Fredericson what are the etiologies of Patellofemoral Pain syndrome
- abnormal Q-angle
- lax ligaments
- abnormal patellar retinaculum and supporting musculotenous flexibility loss gives rise to subchrondral bone stress, pain, map-alignment/tracking
what history is common with patellar femoral dysfunction
- may feel popping
- may have changed activity
what patella images should be taken for patella femoral dysfunction
AP for position
Lateral at 45 degrees fro height
sunrise for articulation
MR, CT, Bone scan
