Salter Harris Fractures

Image source = UptoDate

Podcast for pediatric fractures from freeemergencytalks.net

http://freeemergencytalks.net/2010/11/jonathan-romash-pediatric-fractures/

Let’s start talking about pediatric fractures by talking about some of the features that are unique to them in term of their bones. Kids are growing bodies, and as such they have growth plates at the end of their bones. Terminology that is important to know when discussing pediatric fractures:

Diaphysis = shaft of the long bone

Metaphysis = part that fans out that leads toward the end of the bone

Physis = cartilaginous area of rapid bone growth that doesn’t show up on X-ray well

Epiphysis = distal to physis

Apophysis = Ephysis that arises from an outgrowth of bone that does not attach to another bone (i.e. tibila tuberosity, calcaneous)

Each growth plates has a hypertrophic zone. It is the weakest area of the physis, and the part that causes bony growth. The vascular supply to this area is through the epiphysis. If the vascular supply is messed up (either because epiphysis is destroyed, or because the hypertrophic cell zone is separated from the epiphysis), those are the times you have to worry

about growth failure or significant growth delay. Most of the time this is not the case. Usually the hypertrophic cell zone will separate on the side of the epiphysis à typically, vascular supply is maintained unless it is a particularly severe fracture

** Important to remember that growth plate in kids are weaker than the bone itself and weaker than the ligaments. So where an adult who twists their ankle will commonly get a sprain, pediatric population is more likely to get a fracture. Injury to the growth plate can lead to growth disturbance, growth arrest

Features of pediatric bones that are different from adults = more porus less dense and more rubbery, more plastic-y that can lead to unique fracture patterns as compared to adults

The plastic deformation often observed in children’s long bone fractures is due largely to the complex nature of the molecular and histologic aspects of pediatric bone. Pediatric cortical bone has a lower mineral content than adult bone, accounting in part for its different material properties. Although plasticity allows children’s long bones to absorb more energy prior to fracture, a significant deformity may persist after injury. At the end of the day, pediatric fractures have one big positive over adult fractures: bones are actively growing, they will remodel a lot better than adults and therefore can accept a larger degree of angulation in kid’s with fractures of the long bones as compared to adults

TYPE I (S)

•Seperation/straight across the physis
•Physis itself seperates through the hypertrophic cell zone, but w/ preservation of the periosteal stabilization and preservation of the vascularity
•Usually diagnosed clinically – sometimes see subtle radiographic findings, sometimes see nothing on radiographs
•Kid comes in with injury that is applicable, will have point tenderness right over a growth plate à clinically decide that kid has a Type I
•Go ahead and splint and refer to ortho to re-xray of kids in 10 days to see if there is callus formation to indicate that this really was a salter harris type I fracture
•No real hard data on how many of the presumptive salter harris type I fractures are actually Salter Harris type I since we don’t follow up in the ED, so hard to tell how much we are over estimating on the splinting.

** High yeild USMLE exam salter harris type 1 = SCFE

TYPE II (A)

•Above the physis

•Same separation through the growth plate as seen in type I + fracture coming out through the metaphysis
•small triangular fragment of the metaphysis present on radiograph
•Can have a small disruption of the periosteum, but because it is typically at the tip of the fragment either the proximal metaphysis of where the metaphysis meets the diaphysis, it’s a pretty stable fracture
•From a growth prespective, these kids do very well à splint and refer to ortho follow up
• ** MOST common type of salter harris fractures (75%)
Click image for the outline of the fracture

Type III (L)

•Lower or beLow physis = intraarticular fracture
•“start to get into a little bit of trouble” = fracture goes through the physis, and has intraarticular extension through the epiphysis
•Most of the time the vascularity is preserved. Concern here is if the epiphysis is really trashed à vascularity could be compromised
•By definition of being an intraarticular fracture, they will have all the same issues as intraarticular fracture in adults in terms of really maintaining the alignment for a good functional outcome
•Growth often maintained in these fracture type, but have to ensure that proper realignment is done that the intraarticular fragment is well aligned, often times requiring surgical treatment

Click image for the outline of the fracture

Type IV (T)

•“through two” – intraarticular and goes thru the metaphysis as well
•Fracture that extends through the epiphysis and the whole physis (takes out the growth plate) comes out through the metaphysis
•Often will require an open reduction
•Substantial risk for growth failure
•Compromising vascularity through the epiphysis

Whole physis is affected as well, further hampering growth function

Click image for the outline of the fracture

 

Type V (ER)

•ERasure of growth plate, Ram together
•Caused typically by a profound compressive force destroying the cartilage of the growth plate
•Huge risk of growth arrest
•** Problem is it can be as radiographycally occult as a type 1
•Diagnosis of this fracture is going to be mostly clinical
Quote from EM-RAP C3 review on pediatric fractures:
“two kids w/ tenderness over the growth plate. Both have negative initial x-rays in the ED. The kid who fell off the 8 story building has a type V, kid who fell from a ground level fall has a type I”
Often kids with type V fractures will have joint effusion
References:
Images from Radiopaedia and Uptodate
•1. Weissleder R, Wittenberg J, Harisinghani MG. Primer of diagnostic imaging. Mosby Inc. (2003) ISBN:0323023282.
•Gaillard, Frank. “Radiopedia” Retrieved 2012-09-18.
•”Injuries Involving the Epiphyseal Plate” J Bone Joint Surg Am. 45 (3): 587–622.
•Salter-Harris Fracture Imaging at eMedicine

Compiled by: Sakib Motalib

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