knee Flashcards
direct blow to the front of the knee will usually cause
PCL injury
blows to the side of the knee will usually cause
collateral injury
twisting injuries will usually cause
cruciate rupture or meniscal injury
swelling immediately after injury usually suggests
haemarthrosis
recurrent swelling with normal periods in between usually suggests
chronic internal derangement such as inflammatory arthritis or an old meniscal tear
locking
limitations in extension although flexion is still possible
commonly caused by torn meniscus or loose body caught between articular surfaces
patient may describe being able to manipulate the knee around to unlock it
instability
usually sugests ligamentous injury, but could also be capsular or muscle weakness
how should you start the knee examination
patient standing
exposed joint above and below
exposed contralateral side for comparison
knee examination - look
skin - scars, erythema, lacerations
soft tissue
- effusion most easily detected by absense of the dimple on the medal side of the patella
- muscle wasting of the quadriceps
alignment
- varus and valgus deformities
- genu ricavatum: knee hyperextension
- back of the knee: bakers cysts or popliteal anaeurysms
gait
- antalgic gait: short stance phase on affected side may be a commonn finding
varus deformity may be due to
medial side of the joint affected by osteoarthritis
fixed flexion deformity
position of comfort for the joint, may be due to acute infection
knee examination - feel
sensation, palpating pulses and cap refil time
palpate soft tissue
palpate tibial crest, tibial tuberosity, patella tendon, patella margin, quadriceps insertion, collateral ligaments and joint capsule
palpate the popliteal fossa for swelling or palpable cyst
palpate along the medial joint line to assess for tenderness along the medial colateral ligament
palpate along the lateral joint line for tenderness along the lateral colateral ligament
temperature of the joint
stroke test for effusion: fluid is milked from the medial side of the knee up to the suprapatellar pouch, watch to see if the fluid returns
knee examination - move
active and passive movement comparing both sides
proceed to special tests
lag test
lift leg 10cm off the bed
bend knee 20 degrees and straighten again
if the quadriceps is weak they wont be able to straighten it again
checking for posterior sag
compare the two tibial tuberosities with knees bent
if they’re not at the same level and there is posterior sag on one side, suspect PCL injury
ACL draw test
after ensuring the patient has no foot pain, sit on the patients foot
place fingers in the popliteal fossa and thumbs on the ischial tuberosity
try to bring the tibia forward
repeat on the other joint and compare laxity
lachman’s test
alternative to anterior draw test
knee flexed to 30 degrees
draw tibia upwards
cruciate injury summary
testing the stability of the collateral ligaments
bend knee at 30 degree angle
apply varus and valgus test
which test is used to test for meniscal tears
McMurry’s
McMurry’s test
flex knee to 90
medial: apply valgus stress, externally rotate and extend. Palpated or audible click indicates a medial meniscal tear
lateral: apply varus stress, internally rotate and extend. Palpated or audible click indicates lateral meniscal tear
poor sensitvity and can be painful
test for propensity of patellar dislocation
patellar apprehension test
patients with lax ligaments
more susceptible to patellar dislocation
knee is usually swollen, painful and may be difficult to examine
examine the normal knee to test for propensity to dislocate
patellar apprehension test
test on normal knee for propensity to dislocate/lax ligaments
leg is held over the edge of the bed in an extended position
flexed while patellar is pushed laterally
patella may be encouraged to dislocate laterally, pateint will become veery anxious and the test should be stopped
appley’s test
patient lies prone
tibia is compressed down and rotated into the examination table
if there is more pain with compression than distraction the pathology is likely meniscal
more pain with distraction is likely ligamentous
special tests
lag test for quadriceps weakness
check for posterior sag for PCL injury
anterior draw test for ACL injury
Lachman’s test for ACL/PCL stabilty
valgus/varus stress tests for stability of the collateral ligaments
mcmurry’s test for meniscal injury
patellar apprehension test
apley test for meniscal injury
acute swelling ddx
post-traumatic haemarthrosis = immediate swelling, blood in the joint, painful warm and tense
bleeding disorders
acute septic arthritis
traumatic synovitis
aseptic non-traumatic synovitis (gout, pseudo gout, inflammatory arthropathy)
chronic swelling ddx
intraarticular - osteoarthritis or inflammatory arthritis, synovil disorders eg. synnovial chondromatosis
bony swelling - osteochondroma, osgood-schlatter, maligancy
posterior knee swellinng ddx
baker’s cyst - usually presents in older people with OA, occasionally will rupture and produce pain
semimembranosus bursa
popliteal aneurysm (there will be pulsation in the lump unless thrombosed
baker’s cyst
bulging of the posterior capsule and synovial herniation
seen in the midline
presents in older people with OA
occasionally ruptures and causes pain
semimembranosus bursa
bursa between semimembranosus and gastrocnamius
resolves with time
pulsation in posterior knee lumb
popliteal aneurysm will have pulsation unless thrombosed
anterior knee swelling ddx
prepatellar bursitis
infrapatellar bursitis
other bursae
prepatellar bursitis
front of the patella, often seen in workers who are often on their knees
treatment consists of bandaging and avoiding kneeling
occasionally aspiration is needed
lump may need to be excised in chronic cases
secondary infection is not uncommon
ACL injury
most common knee ligament injury
often ruptured playing sport
commonly occurs when suddenyl changing direction or landing or twisting from a jump
rare for the ACL to heal satisfactorily
what does the ACL do
limits forward movement of the tibia on the femur
also important for rotational stability
why is it rare for the ACL to heal satisfactorily
because the synovial fluid around the ligament prevents formation of a clot required to promote healing response in the ligament
examination of ACL injury
presents with haemarthrosis
anterior draw test
lachman’s test
pivot shift test
ACL injury is confirmed with
MRI scan
management of ACL
depends on age and activity
younger patients under 22 - reconstruct everyone
patients over 35 - try to treat non-operatively
non operative management of ACL injury
conscious control over the knee to minimise rotational instability
risk of repeated damage which can cause irreversible damage to the meniscus
operative management of ACL injury
reconstruction
hamstring tendon autograph hervesting
common orthopaedic procedure with good success rate
most common complication is re-rupture of the ligament
this is reduced by diligent post operative rehabilitation and delaying return to sport by 9-12 months post-surgery
surgery for meniscal teaar
if patient has mechanical symptoms of locking or catching
repair or tear or menisectomy
of the joint is locked and cannot be unlocked, this is an indication for semi urgent surgery
predisposing factors of patellar dislocation
generalised ligamentous laxity
underdevelopment of the lateral femoral condyle and flattening of the intercondylar groove
maldevelopment of the patella, which may be too high or too small
valgus deformity of the knee
external tibial torsion
a primary muscle defect
initial management for patella dislocation
petella reduction - urgent because it is extremely painful
RICE
physiotherapy
recurrent patella dislocation
first time dislocation is generally treated non operatively
first episode is followed in 15-20% of cases with recurrent dislocation or subluxation after minimal stress
management for recurrent patella dislocation
non-operative management
- knee brace: not ideal for long ter due to quadriceps wasting
- physiotherapy
- patella taping
operative treatment
- repair/reconstruct
osteoarthritis
knee is the commonest of the large joints to have OA
often bilateral
4 cardinal signs of OA on radiography
loss of joint space
osteophyte formation
subchondral sclerosis
subchondral cysts
non operative management of OA
activity modification, weight reduction
using a stick or walker
physio
anti-inflammatory
corticosteroid injections
operative treatment of OA
knee replacement
may be total or partial (unicompartmental knee replacement)
unicompartmental knee replacements
advantage of preserving the ligaments
patients feels the knee is more natural
however if the artritis progresses to the other compartment it may need to be revised to total knee replacement to these surgeries have a higher revision rate
