MSK: Trauma and Overuse, General Flashcards
What are the two types of stress fracture?
- Fatigue fracture (abnormal stress on normal bone)
- Insufficiency fracture (normal stress on abnormal bone)
Note: Stress fractures result from the mismatch of bone strength and CHRONIC mechanical force.
Pathologic fracture
Fracture of a bone due to weakening of that bone (underlying lytic lesion such as myeloma met or aneurysmal bone cyst)
Compound fracture
AKA open fracture: A fracture associated with an open wound (e.g. bone protrudes through the skin)
Note: These typically go to the OR for reduction and washout (due to risk of infection).
Tuft fracture
A fracture of the distal phalanx tip, often with disruption of the nail plate
Note: If there is disruption of the nail plate, then this is a type of compound (open) fracture and the pt should get antibiotics (they usually don’t go to the OR, unlike other compound fractures).
What are the phases of fracture healing?
- Inflammatory
- Reparative
- Remodeling
When does granulation tissue start forming around a fracture?
7-14 days after fracture
Note: The fracture will appear more lucent at this time due to bone resorption. This is why some radiologists put “consider repeat in 7-14 days” if they are worried there may be an occult fracture (e.g. scaphoid fracture).
How long does it take fractures to heal?
In general, 6-8 weeks (location dependent)
Note: Healing is fastest in the phalanges (~3 weeks) and slowest in the tibia/femur (~2-3 months).
What factors are needed for proper healing to occur?
- Fracture stability
- Good blood supply
- Proper nutrition
What are the major categories of abnormal fracture healing?
- Delayed union (e.g. twice as long as expected)
- Non-union (not healed after 6-9 months)
- Mal-union (fracture healed but bones are in poor anatomic position)
Salient risk factors for abnormal fracture healing
- Vitamin D deficiency
- Gastric bypass (due to altered calcium absorption)
- Drugs/meds (tobacco use, NSAIDS, prednisone)
What is considered the compressive side vs tensile side of a bone?
Which has a better prognosis: fractures of the compressive side of a bone or fractures of the tensile side of a bone?
Fractures of the compressive side of a bone do better (normal physiology compresses the fracture fragments back together)
Note: Normal physiology pulls fractures on the tensile side apart, making it more difficult to heal.
What is the most common site for a stress fracture in a young athlete?
Tibia (most commonly on the posteromedial “compressive” side)
Anterior tibial stress fractures
Note: These are on the tensile side of the bone and often don’t heal.
What is the compressive side of the tibia?
The posteromedial side
Note: This is the most common location for stress fractures.
What is the compressive side of the femoral neck?
The medial side
Are femoral neck stress fractures more common along the medial or lateral side?
Fractures along the compressive medial side are more common in younger pts
Fractures along the tensile lateral side are more common in older pts
Stress fracture along the compressive (medial) side of the femoral neck
Note: This type of femoral neck fracture is more common in younger pts.
Spontaneous osteonecrosis of the knee
An insufficiency fracture of the knee, classically associated with sudden pain after rising from a seated position in elderly females or in pts with prior meniscal surgeries
Note: This is an insufficiency fracture NOT osteonecrosis.
Sudden pain after rising from a seated position
Subchondral insufficiency fracture (AKA SONK/spontaneous osteonecrosis of the knee)
What is the most common location for spontaneous osteonecrosis of the knee?
The medial femoral condyle (area of maximum weight bearing)
Acute onset pain while getting out of a car
Think subchondral insufficiency fracture (AKA SONK/spontaneous osteonecrosis of the knee)
Calcaneal stress fracture
Note: Look for linear sclerosis that is perpendicular to the trabeculae.
What is the most commonly fractured tarsal bone?
The calcaneus
Note: Calcaneal stress fractures are very common.
Are calcaneal fractures more commonly intra-articular or extra-articular?
Intra-articular (75%)
Navicular stress fracture (navicular is high risk for avascular necrosis, just like the scaphoid)
Note: These are common in runners who run on hard surfaces.
Military recruit
March fracture of the 4th metatarsal
Note: March fractures are metatarsal stress fractures due to walking/marching/running long distances.
Are femoral neck stress fractures high or low risk for abnormal healing?
High risk (if on the tensile lateral side)
Low risk (if on the compressive medial side)
Are patellar fractures high or low risk for abnormal healing?
High risk (if transverse patellar fracture)
Low risk (if longitudinal patellar fracture)
Are tibial stress fractures high or low risk for abnormal healing?
High risk (if along the anterior “tensile” midshaft)
Low risk (if along the posteromedial “compressive” side)
Are metatarsal stress fractures high or low risk for abnormal healing?
High risk (5th metatarsal)
Low risk (2nd and 3rd metatarsal)
Which tarsal bone stress fractures are high risk for abnormal healing?
- Talus
- Navicular
Note: The calcaneus is low risk.
Is a great toe sesamoid fracture high risk or low risk for abnormal healing?
High risk
How can you tell whether a lateral wrist radiograph is truly lateral?
The palmar cortex of the pisiform should be located centrally between the palmar cortex of the scaphoid and the capitate
Lateral wrist radiograph anatomy
Scaphoid
Lunate
Capitate
Triquetrum
Trapezoid
Trapezium
Pisiform
Hamate
