Bone Fractures Flashcards
mechanical functions of bone
*skeleton plays a critical structural role in bearing functional loads
*weight-bearing and muscle loads
*bones act as levers (rigid bodies) to help our musculoskeletal system perform a task
types of mechanical loading
*compression/tension
*bending
*shear
*torsion
bone remodeling & turnover
- osteoBlasts = BUILD bone; derived from mesenchymal stem cell line
- osteoClasts = CRUSH bone; derived from hematopoietic stem cell line
strength of bone
*strength = load bone can bear before breaking
*dependent on: 1) total bone mass; 2) geometric distribution; 3) material properties / tissue composition
simple fracture patterns, correlated to loading mode
- tension → transverse fracture
- compression → oblique fracture
- bending → butterfly fracture
- torsion → spiral fracture
common adult fracture morphologies
*transverse
*oblique (nondisplaced or displaced)
*spiral
*comminuted
common pediatric fracture morphologies
*greenstick (one side broken but other side is not)
*torus
*SALTER classification describes pediatric fractures that occur near a growth plate
pediatric non-accidental trauma
- spiral fracture patterns in non-ambulatory children
- corner fractures
*these 2 fracture patterns raise red flags for non-accidental trauma
common causes of fractures
- trauma
- fatigue
- pathologic
common causes of fractures: TRAUMA
*injury can be one of two mechanisms:
1. direct force - bone breaks at the point of impact; soft tissues also damaged
2. indirect force - bone breaks at a distance from where the force is applied
*typically acute, high energy, and happen when the load exceeds the strength of the bone
most commonly fractured bone
CLAVICLE
clavicle fractures
*mechanism: compression → oblique pattern
*initial tx: sling for comfort
*caution: neurovascular exam
*definitive treatment:
-non operative normally
-surgery if 100% displaced or open
FOOSH - acronym and fractures that result from this mechanism
*FOOSH = fall on outstretched hand
*several fractures can result from this mechanism:
-distal radius
-monteggia
-galeazzi
distal radius fractures
*common mechanism: falling on an outstretched hand
*compression mechanism
*initial tx: reduction, splint
*caution: acute carpal tunnel syndrome
*definitive tx: surgery if unstable or alignment not acceptable after reduction
monteggia fractures
*ulna fracture with dislocation of the radial head
*bones affected proximally
*can occur from FOOSH
*initial tx: splint
*caution: compartment syndrome risk
*definitive tx: operative
MUgger acronym:
-M = Monteggia
-U = ulnar fracture (w/ dislocation of radial head)
-A (monteggia ends in A): A is proximal in the alphabet, so bones affected proximally (close to the elbow)
galeazzi fracture
*radius fracture with dislocation of the distal radioulnar joint
*bones affected distally
*can occur from FOOSH
*initial tx: splint
*caution: compartment syndrome risk
*definitive tx: operative
mugGeR acronym:
-G = galeazzi
-R = radius fracture (w/ dislocation of distal radioulnar joint)
-Z (galeezZi has a Z at the end): Z is distal in the alphabet, so bones are affected distally (near the wrist)
scaphoid fractures
*evaluation: X-rays can be negative; repeat X-ray in 2 weeks or MRI to detect fracture
*presents with tenderness, swelling, pain in snuffbox region
*initial tx: thumb spica cast
*definitive tx: surgery if displaced or not healing
*caution: risk of AVN (avascular necrosis)
common causes of fractures: FATIGUE / STRESS FRACTURES
*occur in normal bone, subject to repeated heavy loading, typically in athletes, dancers, or military personnel
*drugs like steroids and methotrexate
stress fractures
*evaluation: X-ray first; repeat X-ray in 2 weeks or MRI to detect occult fracture
*initial tx: immobilization, weight-bearing restriction
*surgery if displaced or not healing
*consider endocrinology evaluation if no other cause
common causes of fractures: PATHOLOGIC
*caused by condition/disease that led to weak bone
*low energy
*most common cause = osteoporosis
*other conditions: hyperparathyroidism, cancer, infection, bone disorders, bone cysts
how aging can contribute to fracture risk
*normal physiologic aging → decreased bone mass, decreased bone strength, increased brittle bones → increased fracture risk
*bone remodeling = mechanical compensation: shifting effective bone to periphery
-increased moment of inertia as the cortex thins
-increased resistance to bending and torsion
osteoporosis & fragility fractures
*osteoporosis: disease characterized by low bone mass + structural deterioration
*increased bone fragility and fracture risk
*most common fragility fractures = spine, hip, wrist
factors increasing risk of fragility fractures
*increased age (routine screening at age 50)
*gender - more common in WOMEN
*physical inactivity (weight-bearing exercise is good!)
*nutritional problems, including lack of calcium and vitamin D
*chronic medical conditions - endocrine & intestinal disorders
*glucocorticoids
*tobacco & alcohol use
*previous fractures
*family history of osteoporosis
evaluation of a patient with skeletal trauma: general signs
- follow ABCs (airway, breathing, circulatory problems, C-spine injuries)
- secondary survey - examine the main injury, ascertain type of fracture, classify
- brief history, including history of trauma (ascertaining the mechanism of injury is important)
evaluation of a patient with skeletal trauma: SYMPTOMS
*pain
*bruising
*swelling
*numbness or loss of movement
*deformity - more suggestive of a fracture
evaluation of a patient with skeletal trauma: physical exam
- LOOK:
-swelling, bruising, deformity
-examine whether the skin is intact
-note the posture of extremity and color of skin - FEEL:
-gently palpate injured part
-test vascular and peripheral nerve abnormalities - MOVE:
-crepitus & abnormal movement may be present
-more important to ascertain if the patient can move the joints distal to the injury
fracture description: closed vs. open
*closed = skin intact
*open = open wound in skin communicates with fracture site (requires prompt administration of antibiotics to reduce risk of infection)
-usually a 1st generation cephalosporin
X-ray investigation of fractures
*X-ray examination is MANDATORY for any trauma, injury, or bony to palpation
*rules of twos:
1. 2 VIEWS - lateral and AP
2. 2 LIMBS - especially in children
3. 2 JOINTS - should be able to see joint above and below the fracture
4. 2 INJURIES - severe force often causes injuries at more than one level
5. 2 OCCASIONS - if you don’t see a fracture but suspect it, repeat X-ray 2 weeks later
final description of fractures
- open vs. closed
- which bone is broken? where?
- has it involved a joint surface?
- what is the shape of the break?
- is it stable or unstable?
- is it a high-energy or low-energy injury?
indications for advanced imaging in fractures: CT SCAN
*peri-articular fractures:
-tibial plateau
-pilon fractures
-pelvic ring/acetabular fractures
-foot fractures
*pathologic lesions - bony
*tumor/oncologic processes
indications for advanced imaging in fractures: MRI
*suspected ligamentous or other intra-articular injury:
-spine
-shoulder (rotator cuff)
-knee (ACL, PCL, etc)
*stress fractures
*tumors/oncologic processes
advanced imaging in fractures - overview
*should only follow a plain film for the purposes of:
-further clarifying the injury/disease process to aid in the development of a treatment plan
OR
-when needed in the setting of otherwise normal x-rays to help diagnose or better delineate anticipated pathology that cannot be seen on plain x-ray
primary bone healing
*INTRAMEMBRANOUS OSSIFICATION: woven bone formed directly, without cartilage
1. cutter cones re-establish Haversian structure of cortex
2. osteoclasts at tip of capillary bud cuts tunnel into cortical bone
3. behind this a cuff of osteoblasts lay down new concentric lamellae
*in order to have primary bone healing, need absolute stability; rigid fixation
*strain < 2%
secondary bone healing
*ENDOCHONDRAL OSSIFICATION (cartilage precursor before healing with bone):
1. stage 1 = tissue destruction and hematoma formation (7 days)
2. stage 2 = inflammation and cellular proliferation/granulation tissue (2-3 weeks)
3. stage 3 = callus/woven bone formation (4-12 weeks)
4. stage 4 = remodeling into compact bone (1-4 years)
*occurs with non-rigid stabilization
*strain 2-10%
mechanisms of bone fractures: tension
*when the bone is pulled apart from top to bottom
mechanisms of bone fractures: compression
*when forces are applied to the bone from both the top and bottom of bone
*“squishes” the bone
mechanisms of bone fractures: bending
*when force on the bone causes it to distort into a curved shape
*ex: greenstick fracture in pediatrics
mechanisms of bone fractures: shearing
*when nontwisting pushing or pulling forces are applied to the top and bottom of a bone in opposite directions
mechanisms of bone fractures: torsion
*when TWISTING forces are applied to the top and bottom of a bone in opposite directions
*like wringing out a towel
mechanisms of bone fractures: avulsion
*when part of the bone is forcefully torn away from the rest of the bone
Salter-Harris classification of growth plate injuries: type 1
*fracture runs straight across the growth plate
*the epiphysis is separated from the metaphysis
Salter-Harris classification of growth plate injuries: type 2
*involves a fracture above the growth plate, through the bony metaphysis
*most common type of growth plate injury
Salter-Harris classification of growth plate injuries: type 3
*fracture is lower than / below the growth plate
*involves a horizontal fracture through the growth plate and a vertical fracture of the epiphysis, creating a right angle
Salter-Harris classification of growth plate injuries: type 4
*fracture through the metaphysis + growth plate + epiphysis vertically at an angle
Salter-Harris classification of growth plate injuries: type 5
*fracture is due to a compressive force that crushes (erases) the growth plate by pushing the epiphysis into the metaphysis
