Knee pathophysiology: fracture and degenerative changes Flashcards
how do we screen for fractures at the knee?
ottawa knee rules (Sn 98.5%, Sp 48.6%)
Pittsburgh decision rules (Sn 99%, Sp 61%)
what is the criteria for the ottawa knee rules?
> 55 years old
tenderness at the head of fibula
isolated tenderness of patella
inability to flex knee to 90º
inability to walk for weight bearing steps immediately after injury and in the emergency room
what is the Pittsburgh decision rules?
if the MOI was blunt trauma or fall and one of the following:
age <12 y/o or >50 y/o
inability to walk four weight bearing steps in the ER
what are the types of fracture in the knee?
distal femoral shaft
tibial plateau
patella
what is the MOI for a distal femoral shaft fracture?
MVA or fall from great heights
low level force or minor fall
what are the classifications for a distal femoral shaft fracture?
non displaced
impacted
displaced
comminuted
condylar
intercondylar
what is the incidence rate for distal femoral shaft farctures?
97% fractures > 60 years (females 71.6 years > males 44.1 years)
61% fall from standing height
what is a distal femoral shaft fracture?
disruption of the distal femoral shaft; often displaced fracture and/or comminuted (spiral, transverse, oblique)
may lead to massive internal hemorrhage -> shock
what is the clinical picture for a distal femoral fracture?
grossly swollen, deformity apparent, often unstable
what is the non-operative management for distal femoral fractures?
fewer risks than surgical management however length of time for healing/recovery is much greater
continuous skeletal traction followed by 3-6 weeks of casting
what is the operative management for distal femoral fractures?
internal fixation- use of large intramedullary nail to stabilize fracture site
may utilize an open (ORIF)
what are some complications of distal femoral fractures?
mal-union (rotated or shortened limb)
joint and or soft tissue adhesions
post traumatic DJD
what percent of overall fractures do proximal tibia fractures contribute to?
1%
what is the MOI for proximal tibia fractures?
impact with automobile fenders (25%)
axial loading as a result from a fall
individuals with osteoporosis (8% of all fractures in older individuals)
what is the clinical picture for proximal tibia fractures?
knee effusion, pain, joint stiffness
what are some complications of proximal tibia fractures?
intra-articular and peri-articular adhesions and DJD
where do proximal tibia fractures typically occur in adults?
at medial and lateral tibial plateau in individuals 40-60 years
what is the MOI for adult proximal tibia fractures?
valgus or varus force with axial compression
car pedestrian accident bumper -> knee
elderly with osteoporosis after twisting
where do proximal tibia fractures typically occur in chidlren?
in epiphyseal growth plate and metaphyseal region (3-6 years)
what is the MOI for children proximal tibia fractures?
fall
varus/valgus force with axial load
what are the imaging options for proximal tibial plateau fractures?
x ray (AP, lateral, and oblique views- parfaot sign)
CT may be indicated to determine extent of fracture line
MRI indicated if associated with suspected ligament injury
what is the pathophysiology for proximal tibial plateau fractures?
may see a split (younger) or a depression fracture (older)
more common lateral plateau
may also contribute to ACL tear
at what age range do patellar fractures generally occur in males and females?
males 10-19 years
females 60-80 years
what is the MOI for patellar fractures?
direct: fall (crush fracture)
indirect: jumping (avulsion fracture)
stress fracture
what is the clinical picture for patellar fractures?
pain/tenderness around patella
joint effusion
history of direct or indirect injury
how are patellar fractures diagnosed?
radiographs- AP, lateral, merchant (tangential) view
CT- utilized when fracture is not visible on radiograph
bone scan
what is the non operative management for patellar fractures?
non or minimally displaced fracture site
immobilization 4-6 weeks with FWB and crutches
what is the operative management for patellar fractures?
significant fragment displaced, articular incongruity or open fracture
pin and wire fixation
when is a patellectomy indicated?
with comminuted fracture
what are some complications of patellar fractures?
DJD, loss of quadriceps strength
what percent of all knee injuries are patellar dislocations?
2-3%
who more commonly experiences patellar dislocations?
young active individuals
adolescent females and atheltes
lateral > medial
what are 2 risk factors for patellar dislocations?
increased Q angle, weak VMO
what is the normal Q angle for males and females?
18º for females and 13º for males
what does an increased Q angle lead to?
higher likelihood of lateral patellar tracking
how do we measure a patients Q angle?
patient supine with knee in full extension
PT stands on measuring side
mark the following landmarks: F-midpoint of patella, PA- ASIS, DA- tibial tubercle, align goniometer
positive result is if <13º or >18º
how do we treat a patellar dislocation?
reduction of dislocation
exercise
modalities
taping
bracing
lateral retinacular release
what is the most common form of OA?
knee osteoarthritis
what is the incidence for knee OA?
affects > 16 million Americans
age > 60 years
what is the joint disease progression for knee OA?
loss of cartilage, bony sclerosis, increased subchondral bone growth, bone cysts, osteophyte formation
what is the clinical picture for knee OA?
pain and stiffness at knee
how is knee OA diagnosed?
clinical picture in combination with x-rays
x-ray finding of decreased joint space correlates poorly with clinical symptoms
what are some pharmacological managements of knee OA?
non-opioid analgesics (acetaminophen, tylenol)
over the counter NSAIDs (ibuprofen)
prescription strength NSAIDs
topical analgesics (capsaicin, methylsalucylate creams)
intra-articular hyaluronan injections
intra-articular steroid injections
opioid analgesics (codeine)
what are some non pharmacological managements of knee OA?
PT, surgery (TKA or PKA)
what is gout at the knee?
excessive amounts of uric acid
what is pseudogout of the knee?
calcium crystals
most common in the knee
what are some risk factors for pseudogout?
uncommon in premenopausal women
hyperparathyroidism
chronic kidney disease
diuretic use
what is the clinical picture for proximal tibial fractures?
knee effusion
pain
joint stiffness
what are some complications of proximal tibial fractures?
intraarticular and periarticular adhesions
DJD
what is osteochondritis dissecans (OCD)
chronic form of osteochondral fracture
85% medial femoral condyle
occurs in older children, teens and younger adults
what are symptoms of osteochondritis dissecans?
dull pain
joint effusion (chronic)
loose body in joint common
what is the MOI for OCD?
shearing and rotational force -> articular cartilage fragment and subchrondral bone
what imaging is done for OCD?
MRI, x-ray
what is reactive arthritis (Reiter’s Syndrome)?
swelling triggered by an infection
primarily affects young males age 20-40
usually affects knees and ankles
what are the symptoms for reactive arthritis?
pain and stiffness
eye inflammation
urinary problems
swollen toes or fingers
skin problems
low back pain
what is the criteria for advancing to phase 2 of treatment of OCD?
full passive knee extension
knee flexion to 125º
minimal pain and swelling
voluntary quadriceps activity
what is rheumatoid arthritis?
autoimmune disorder
occurs immune system mistakenly attacks body’s tissues
what are some symptoms of rheumatoid arthritis?
tender, warm, swollen joints
joint stiffness that is usually worse in the mornings and after inactivity
fatigue, fever and loss of appetite
what are some risk factors for rheumatoid arthritis?
women > men
smoker
family history
middle age onset
environmental exposure
obesity
what is septic arthritis?
typically caused by bacterial infection spread through the blood stream
usually only affects one joint- knee or hip
most likely to occur in children and older adults
what are some risk factors for septic arthritis?
open wounds
weakened immune system
cancer
diabetes
IV drug use
what are some symptoms of septic arthritis?
chills
fatigue and generalized weakness
fever
inability to move the limb with the infected joint
severe pain in the affected joint, especially with movement
swelling
warmth
how is septic arthritis diagnosed?
arthrocentesis
