48. Knee and lower leg injuries Flashcards
What kind of joint is the knee?
modified hinge
Is the head of the fibula part of the knee joint?
no
What two aspects make up the knee joint?
tibiofemoral
patellofemoral
What is the trochlea of the femur?
anatomic structure resembling a pully, which is made by the femoral condyles on either side
allows patella to slide up and down
What 4 ligaments attach the tibia to the femur?
acl
pcl
mcl
lcl
Where does the ACL arise and attach?
arise: medial surface of lateral femoral condyle nad inserts on anterior surface or tibial plateau within the tibial intercondylar note
(APEX)
Where does the PCL arise and attach?
meedial femoral condyle to insert on the posterior surface of the tibial plateau in the intercodylar notch
(PAIN)
What is the role of the ACL?
prevent excess anterior displacement of the TIBIA on the femur
control rotation and hyperextension
MC injured ligament in the knee?
ACL
What is the role of the PCL?
prevent excess posterior displacement of TIBIA on femur
esp in flexion
++ stronger than ACL
Name 4 medial stabilizers of the knee
joint capsule
mcl
semimembranosus
pes anserine
What is the role of the medial stabilizers of the knee?
resist valgus laxity and medial rotatry instability
Where does the MCL arise from and insert?
medial fem condyle
onto medial tibia
Lateral knee stability - name 2 main structures and their role
LCL
lateral joint capsule
resists varus deformity
where does the LCL arise/insert?
lat fem condyle
onto fibula
what structures further stabilize the lateral aspect of the knee (other than LCL, lateral joint capsule)
ITB
biceps tendon
portion of posterolateral corner (particularly popliteal tnedon)
3 knee compartments
patellofemoral
medial tibiofemoral
lateral tibiofemoral
What key structure is in the patellofemoral compartment of the knee?
quads tendon
What key stuctures are found within the medial tibiofemoral compartment?
medial femoral condyle
medial tibial condyle/plateau
medial meniscus
MCL
adductor tubercle
pes anserine
What 3 structures make up the pes anserine?
gracilis
sartorius
semitendinosus
What structures are found inside the lateral tibiofemoral compartment of the knee?
lat fem condyle and epicondyle
lat tibial plateau/condyle
LCL
lateral meniscus
popliteus tendon
NOT FIBULAR HEAD
What is the fabella, found in some patients?
sesamoid bone in lateral head of gastrcnemius
What are the borders of the popliteal fossa?
lateral: biceps fem tendon
medial: semit and semimembranosus m
inferior: two heads of gastroc m
What 4 key structures are found within the popliteal space?
a
v
peroneal and tibial nerves
What artery are you worried about in knee dislocations?
popliteal a
Popliteal a is a continuation of what a beyond the adductors?
femoral
What three arteries are part of the trifurcation of the popliteal a?
anterior and posterior tibial a –> peroneal a then branches from posterior tibial a
What are the a that come from the popliteal a to the knee joint?
geniculate a
What two nerves are responsible for innervation of the knee?
tibial
common peroneal
Name 7 parts of the extensor mechanism of the knee
quads m
quad tendon
medial and latearl retinacula
patella
patellar tendon
tibial tubercle
What holds the patella in place?
quads tendon
patellar tendon
medial and lateral retinacula
How does the patellar increase effective lever of the quads in the extensor mechanism?
anteriorly displaces the quad tendon
What is the role of the menisci?
sit on top of tibia to functin as shock absorbers, distribute stress across joint surface
deepen the tibial plateau
Which menisci is more at risk of injury and why?
lateral - more mobile
Menisci are mostly avascular, except which part?
middle 1/3 ie best chance of healing after injury
ITBand connection? role?
iliac crest to lateral tibial tubercle
stabilizes knee joint in extension
Where is the popliteus found?
lat fem condyle to posteromedial tibia, capsule and lat meniscus
What does the popliteus do?
- prevents ER of tibia
- withdraws lateral meniscus during flexion to prevent femur/tibia impingment
- with PCL and quads, stabilizes knee (prevents forward displacement of FEMUR on tibia)
Where is the prepatellar bursae?
between patella and skin
Where is the superficial intrapatellar bursa?
between tibial tubercle and skin
Deep intrapatellar bursa. - where?
posterior margin of distal part of patellar tendon and anterior aspect of tibia
Where is the suprapatellar bursa? True bursa?
not true
actually ext of tibiofemoral joint capssule so it grows with knee effusion
Does the prepatellar bursa communicate with the tibiofemoral joint?
no
Where is the pes anserine bursa found?
between pes anserine and mcl/medial tibial condyle
Per Rosen’s box 48.1, what are the 5 aspects to examination of the knee?
- Assess neurovascular integrity of the foot.
- Determine whether a knee effusion is present, and assess for gross defor-
mity or open wounds. - Identify signs of infection—redness, warmth, and effusion out of propor-
tion to mechanism of injury. - Localize tenderness.
- Assess for range of motion, stability, and the integrity of the extensor
mechanism.
List 9 sites of palpation that may be tender in the knee
1, Quadriceps tendon injury;
2, prepatellar bursitis, patella pain; 3, retinacular pain after patella subluxation;
4, patella tendon injury;
5, fat pad tenderness;
6, tibial tubercle pain as in Osgood-Schlatter, but also consider tibial plateau frac- ture in the right setting;
7, meniscus pain or arthritis;
8, collateral ligament pain;
9, pes anserine tendinitis-bursitis
DDX knee dislocation
Patellar dislocation, distal femur fracture, tibial plateau fracture
DDx distal femur fracture
Tibial plateau fracture, knee dislocation, quadriceps tendon rupture
DDX tibial plateau fracture
Distal femur fracture, knee dislocation, patellar fracture, patellar dislocation, tibial spine fracture, patellar tendon rupture
DDX tibial spine fracture
Tibial plateau fracture, patellar tendon rupture, anterior cruciate ligament (ACL) injury
DDX osteochondritis dissecans
Distal femur fracture, tibial plateau fracture, meniscal injury
ddx OA knee
Distal femur fracture, tibial plateau fracture, meniscal injury, chronic ACL deficiency, osteochondritis dissecans
DDX quads/patellar tendon injury
Patellar fracture, patellar dislocation, distal femur fracture, tibial spine fracture, tibial plateau fracture
DDX patellar fracture
Patellar dislocation, quadriceps/patellar tendon rupture
DDX patellar dislocation
Patellar fracture, quadriceps/patellar tendon rupture
DDX cruciate ligament injury
Meniscal injury, collateral ligament injury, distal femur fracture, tibial plateau fracture, tibial spine fracture
DDX collateral ligament injury
Posterolateral corner injury, meniscal injury, cruciate liga- ment injury, distal femur fracture, tibial plateau fracture
DDX meniscal injury
Collateral ligament injury, cruciate ligament injury, osteochondritis dissecans, distal femur fracture, tibial plateau fracture
Overuse syndromes of the knee - 3 injuries possible
Cruciate ligament injury, collateral ligament injury, osteochondritis dissecans
DDX for a large knee effusion
1) TRAUMA distal femur fracture
ACL or PCL injury
dislocation
tibial plateau or spine fracture
2) NO TRAUMA
insufficeincy fracture
septic arthr
inflamm arthr like gout
hemarthrosis or lipohemarthrosis from occulr fracture
avn
ruptured baker’s cyst
malignancy
DDX for anterior knee pain
patellofemoral knee pain
Osgood-Schlatter
fracture
Saler Harris type I foemoral or tibial aphysis fracture
tibial plateau fracture
osteochondritis dissecans
quad rupture
Osteochondrtis dissecans gradual pain onset picture
on femoral condyle
Special tests for ACL:
Anterior drawer/Lachman: how to do
supine
hip at 45
knee at 90
thumb on joint line and pull tibia forward
thumbs feel for any tibia translation relative to femur
+ if > than other knee
Lachman is similar - but knee is flexed 20-30 deg
one hand to stabilize femur
then pull tibia ant and feel if can get firm or soft end point
Lachman grade for endpoint
1+ (0=5mm more displacmeent than N side)
2+ (5-10mm)
3+ (>10mm)
Posterior drawer test: how to do
The posterior drawer test can be accomplished with the patient’s knee flexed at 90 degrees and the foot stabilized by the examiner. A smooth backward force is applied to the tibia. Posterior displacement of the tibia more than 5 mm, or a soft end point, indicates injury to the PCL.
Posterior sag sign for PCL - how to do
supine position, and a pillow is placed under the distal thigh for support while the heel rests on the stretcher. The knee is flexed to 45 or 90 degrees. If the tibia sags backward, the test result is considered to be positive, indicating PCL insufficiency.
laso may be appreciated during passive eleva- tion of the leg in a fully extended position, with the examiner applying the elevating force at the ankle.
Testing for LCL/MCL laxity - how to do?
patient lying supine, the examiner applies varus and valgus stress with the knee at 0 and 30 degrees of flexion. Joint line opening is the amount of movement produced between the tibia and femur; this can be palpated and estimated in millimeters. The normal knee should be subjected to the same amount of valgus and varus stress;
Grading for LCL-MCL laxity - grade i vs ii vs iii
grade I (some laxity), grade II (marked laxity), and grade III (total laxity).
How to perform McMurray test for meniscal tears?
supine, knee hyperflex
examiner grasps foot one hand, knee with other
flex and ext knee while IR and ER tibia on femur for valgus and varus test
+ if clicking palpable at joint line, pain or locking of knee
What things can be seen on xray imaging of the knee (helpful findings)
FB
sublux
dislocation
fracture
jt space narrowing
What findings on plain XR are suggestive of ligamentous injuries of the knee?
effusion
- lipohemarthrosis suggestive of fracture if there is a linear interface between two densities
Ottawa knee rule indications - how old can the injury be?
7 days
Standard knee trauma xray views
AP
lateral
sunrise
What is a tunnel view of an xray and why is it helpful?
image intercondylar notch, useful for tibial spine fracture
what is an oblique xray of the knee helpful for?
tibial plateau #
Which imaging modality for knee dislocation?
cta for popliteal a
Ottawa knee rules:
any + = xray
age >55
patellar tenderness
isolated fibular head tneder
flexion <90 deg
inability to wbear 4 stepps immed after injury or in ED
Pittsburgh knee rules - any + for xray
age <12 or >50
inability to walk 4 steps
More sn and sp than ottawa
What kind of joint is considered a surgical emergency?
open
How to assess if unclear if joint is open?
ct imaging
or sterilesaline load with 200ml into joint capsule and see if comes out of laceration *don’t use meythlne blue not more sn
What is an arthrocentesis useful to see?
effusion
hemarthrosis
lipohemoarthrosis
rheum conditions
septic arthritis
Five types of knee/ tibiofemoral dislocation
what are they
how is it described (ie femur and tib relation)
ant, post, med, lat, rotary
tibia relative to femur
Mc knee dislocation and mechanism
ant
hyperext
mechanism of posterior dislocation of knee
high velocity direct trauma to a flexed knee
Peroneal nerve assessment post knee dislocation - how to do?
sejsation dorsum of foot
dorsiflex ankle
Delayed complications assoc with traumatic knee dislocation
dvt
compartment syndrome
pseudoaneurysm
arterial thrombosis
Longer term complication of knee dislocation found in almost half of dislocated knee
heterotopic ossifciation
How can the popliteal a be assessed?
abi
cta
duplex ultrasound
ABI >0.9 - popliteal a NPV?
approaching 100%
Hard signs of a vasulcar injury - list 5
lack of distal pulse
palpable thrill
pulsatile hemorrhage
expanding hematoma
classic 5 p’s - pain, pallor, parethesia, poikilothermia, paralysis
list 4 soft signs of vascular injury
decreased pulse relative to uninjured side
sign hemorrhage at time of injury
nonexpanding hematoma
peripheral n deficit
Knee dislocation management in the ED
- reduce it during secondary survey asap –> traction, counter traction
- neurovascular status
- immobilize in a long leg posterior splint, knee 15 to 20 deg of flexion post reduction
open joint - cefazolin 2g IV
- any hard signs of vascular injury = OR
5.soft signs = angiogram
Distal femur fracture complications
thrombophlebitis
fat embolus
delayed union or malunion
Distal femur fracture ed management
- Pain
- splint
- ortho emergent
if uncomplicated fracture dislocation, can skeleton traction adn immobilixe vs intrarticular ORIF
Tibial plateau fracture - mechanism?
valgus force with axial loading
What does a segond fracture make you think of?
likely acl disruption, can occur with tibial plateau fracture
What neurovascular compromise can tibial plateau fractures cause?
popliteal a
perioneal n
anterior tibial a
What on a plain film is suggestive of a tibial plateau fracture?
lipohemarthrosis
Absolute indications for tibial plateau fracture ortho consult
joint instability
open fracture
nv compromise
compartment syndrome
ED management tibial plateau
- pain
- neurovascular assessment
- knee immobilizer
- dvt tx consideration ind basis after talking with ortho
Anterior tibial spine fracture - assoc with which ligament tear?
acl
Tibial spine fracture mechanism
knee twist
hyperflexion
hyperext
valgus/varus forces
xr for tibial spine fracture
ap lat
tunnel view
Tibial spine fracture ed management
knee immob
nwb
ortho 3-7d
Osteochondritis dissecans: what is this?
rare dis
adolescent
partial or torn separation of segment of articular cartilage and subchondral bone from underlying bone
Osteochondritis dissecans: where is this often seen in knee?
nwb lateral aspect of medial femoral condyle
Osteochondritis dissecans sx
pain
swelling
giving way episodes
Osteochondritis dissecans XR findings
subcortical lucency
osteocondral fragment
Osteochondritis dissecans ed management
nwb
limit activity
ortho 3-5d
mechanism of quads tear
sudden contraction of quads m with knee in flexed pos, laceration or direct blow
RF for a quads tear
ra
gout
sle
hyperparathyroidism
iatrogenic immunosuppresion with CS
?fluoroquinolones
Quads tendon/extensor disruption signs on exam - 4 different clinical presentations
- acute onset of pain and ecchymoses over anterior aspect of knee and palpable defect in the patella, quads tendon or patella tendon
- loss or limitation of active leg ext with ext lag noted in last 10 deg of manuever
- high riding patella iwth patellar tendon rupture and superior retraction
- low riding patella with quad tendon rupture and inferior retraction
quads tendon rupture image findings
xr - patella alta with Insall salvati ratio (patellar length to patellar tendon length ratio if <0.8 = +)
obliteration of quad or patella tendon
calcific defnsities
if partial –MRI best
ED management of quads/patellar tendon tears
knee immob
nwb
ortho 1 wk
Patella fractures: xr to do
ap
lat
sunrise
Patellar fractures: classifcation
transverse
stellate
comminute
lorg or marginal
prox or distal pole
patellar dislocation mechanism
valgus stress on a flexed knee = ER of leg
Patellar dislocation closed reduction technique
knee passively ext while inferomedial directed pressure applied to patella
post patellar reduction, need xr. why?
ensure no osteochondral avulsion fragment as may need arthroscopy for removal
post reduction of patella dislocation: ed management
knee immob in full ext
f/u ortho 1-2 weeks
Unhappy triad
acl
mcl
medial meniscus tear
Unhappy triad actually less common than what triad seen?
acl
mcl
lat meniscus
PCL injury mechanism
posterior force on flexed knee
MCL injury mechanism
direct blow or impact to lateral knee
LCL injury mechanism
hyperextension with varus stress
with direct blow or rotation
++ peroneal nerve assessment
XR for cruciate and collateral liagment injuries
AP
lat
sunrise
intracondylar notch views
Manageemnt of isolated ligament knee injuries in the ED
fully unlocked
hinged knee brace with w bearing as tolerated
ortho f/u 1 week
Meniscus tear - which part most often injured?
posterior due to increased forces on posterior horn with knee flexion
Which part of meniscus has best blood supply?
lateral
but unfortunately medial most often injured
Meniscus diagnosis in the Ed?
Not really
MRI and arthroscopy best
Management of meniscus in the ED
Unlocked hinge knee brace
Crutches
Ortho follow up
Patellofemoral syndrome epidemiology
Women
20 and 30
Gradual no trauma
With pain after ongoing flexion
RF patellofemoral syndrome
Glute weakness or quad
Patella subluxation
Prepatellar bursitis
Arthritis
Meniscus tear
Quads and patella tendinipsthy
Physical exam patellofemoral syndrome
Med and lat patella tender
Recreate on single leg squat
Management of patellofemoral pain
NSAID
Pt
ITB syndrome - in who? Where?
Runners
Lat femoral epicondyle
Pain or tightenness by ober test
How to perform ober test?
Injured leg up on side
Flex 90, 90 hip and knee
Abduction hip, knee extend then hip aducted
If can’t do above adduction with gravity or get pain same spot indicates tight
Treatment ITB syndrome
Relative rest
NSAID
Pt
Patellar tendon path y management
Relative rest
PT
Anti inflam
Plicq syndrome what is this?
Ongoing embryonic tissue in the knee that may thicken tissue due to ongoing repetitive movement or minor trauma
Plica syndrome findings on exam and imaging
Medial femoral condyle tender
Snap or pop - worse run or sit
Arthroscopy as often won’t see mri
Plica syndrome management
Pt
NSAID
While awaiting ortho appt
Classic presentation of popliteal tendinopathy
Increasing posterior knee pain going down hill
Webb test for popliteal tendinopathy
Differentiate from bicep fem tendinopathy or lat meniscus or ITB
Supine, flex knees to 90. Rotate leg IR, then resist examiner ER
If + pain = + test for pop tendinopathy
Bursitis is a ___ dx
Clinical
Standard fluid studies for bursitis
Pro
Glucose
Gram stain and culture
Cell count
Crystal analysis
Plus Lyme and gonorrhea if warranted
Septic bursitis without joint involvement management
Abx
Staph aureus x10d
Fail = I and d
Aseptic bursitis management
Drainage
Then compression
Ice rest
NSAID
OA on X-ray
Osteocytes
Subchondral cyst
Subchondral sclerosis
Joint space narrowing
Management of OA
Pt
NSAID and Tylenol
Limited use of CS
What is a baker cyst?
Herniation of synovial membrane through posterior aspect of knee capsule
Signs of baker cyst
Posteromediak corner of knee mass
Pressure pain limited rom
R:o dvt
Tx of bakers cyst
NSAID
Rest
Compression
Output drainage
3 a of the lower leg
Come From popliteal a
Anterior tibial a
Posterior tibial a
Peroneal a
4 compartments of the lower leg
Anterior
Lateral
posterior superficial and deep
Lateral compartment m
Peroneus longed and Brevis with superficial peroneal n
Superficial posterior compartment of leg structures
Gastroc
Soles
Plantaris
Sural nerve
Deep posterior compartment of leg structure
Rib post
Long toe flexor m
Posterior tibial and peroneal a
Tibial n
Subcondylar tibial fracture: associated with which knee fracture?
Tibial plateau
Subcondylar tibial fracture mechanism
Rotational stress and vertical compression
Tibial tuberosity fracture: type I
Incomplete avulsion
Tibial tuberosity fracture: type ii
Complete avulsion extra articular
Tibial tuberosity fracture: type iii
Complete avulsion
Intraarticular
Which subcodnylar tibial fractures require or?
Intraarticular
Communuted
Displaced
High risk for compartment syndrome!!
Two classification systems for tibial tubercle fractures
Ogden
Watson - Jones
Name the Ogden classification types of tibial tuberosity fractures
Type 1: secondary ossification fracture
2- fracture between primary and secondary centres
3- fracture extender primary centre of ossification site
4- entire proximal tibial physis fractured
5- sleeve avulsion fracture from secondary ossification centre
A- nondisplaced
B- displaced
Tibial shaft fracture high risk of which n injury?
Peroneal
RF of tibial shaft fracture
Dvt
Fat embolus
Non union
Pseudoaneurysm
Av fistula
When to add gent to open fracture?
Severely contaminated
When to add pen G to open wounds)
Farm related
When to add pseudomonas coverage to open wound?
Fresh or saltwater
Recommended splint for tibia shaft fracture
Long leg posterior sugar tong component
Maissoneuve fracture components
Medial ankle disruption with a deltoid lig tear or fracture at medial mall
Complete syndesmosis tear
Proximal fib fracture
Isolated fibula fracture management
Ice
Analgesia
Stirrup splint
NWB
When to consult ortho for fib fractures (immediate)
Maissoneuve
Fracture of fib severely displaced or with peroneal n injury
Mc tib fib joint dislocation
Anterolateral
Posteromedial tibfib joint dislocation nerve injury risk?
Peroneal
Proximal tib fib joint dislocation - relocation technique
Knee at 90, every ankle and direct pressure on fibular head
Then to ortho!
Mc sites stress fracture
Tib fib femur navicular metatarsal bones
Stress fracture (general) management
Decrease activity 3-6 weeks to heal
Which stress fractures need to be made NWB given risk of progression complete fracture?
Ant TiB
Navicular
Fifth metatarsal
Patella
Seamus
Superior sided femoral neck
Why does medial tibia stress syndrome/shin splints occur?
Periostitits
Lack of discrete fracture line
