7/25/2019 IMG_20160129_0001

1/1

CopyRrcHr

O

2013 By TnE

JounNer

oF

BoNE AND

IorNr

Suncrnv, INcoRpoRATED

S

AraEnrcaN

AceoBuv

or

Oxtnoparorc SuRcEoNs

ExHrsrr

SsrECTroN

Atypical Femoral

Fractures:

What

Do

\Afe

Know

About Them?

AAOS Exhibit Selection

Aasmanuntana,ML Anas Saleh,M2Kon A Mensah,MnMAohn R Kleimeyer,Rand IOseph M.pMD

Lu

pFFo

iri

q N_

g

tt

P

ar

MbX

T

y

isphosphonates

are

the most

commonly

prescribed

qpe

of medication

for

the

treatment

of

osteoporosis.

Studies

have

shown

that

bisphosphonates reduce

the

inci-

dence

of

vertebral and nonvertebral fractures when used to

treat

postmenopausal

osteoporosis'- .

The indications for

use

of bisphosphonates aiso

extend

to

other metabolic

bone

diseases

such

as

glucocorticoid-induced

osteoporosis,

Paget

disease, hlpercalcemia due

to a variety of

causes,

and

skeletal

metastases5-'.

Treatment

with

bisphosphonates,

however,

is

not

without

adverse effects.

Because

bisphosphonates

act

by

inhibiting osteoclast function

and

inducing osteoclast apo-

ptosisu'',

there

is

a substantial concern regarding

the

potential

side effects

related

to

severe

suppression ofthe

bone

turnover

rate,

Several

case

reports

and

case

series

have

indicated

an

as-

sociation between a unique

fracture type, so-called

atypical

femoral

fiactures,

and

prolonged bisphosphonate

use'o- .

These

fractures differ

from

typical osteoporotic

femoral frac-

tures

in many respects, including the mechanism

of injury

location, and

fracture

configuration.

Although

the

American

Society for Bone

and

Mineral Research

(ASBMR)

published

a

task

force report on atypical femoral fractures

in

2010 , little

information

about

this

type

of fiacture

is known.

The

present

report

will

critically

review

current

evidence

on

the

charac-

teristics, epidemiology,

patlogenesis,

and

treatment

outcomes

of

atypical femoral

fractures

to

identifr

gaps

in knowledge

calling

for future

research

and

to

provide

guidance

for

ortho-

paedic

surgeons.

..,..:

l\ zfuny

case

reports and

case

reviews have

described

several

lYlcommon

radiographic

features

of aqpical femoral

frac-

tures associated

with bisphosphonate

use,

including a

transverse,

noncomminuted

fracture

at

the subtrochanteric or femoral shaft

region

with

a

medial cortical

spike

at

the

fiacture

area

(Fig.

1).

Other features include

prodromal

pain

and

generalized

thick-

ening

of

the femoral

cortices on

radiographs.l{'16'i/-.

Because

of

the lack

of

clear

criteria to

define atlpical

femoral

fractures,

the

ASBMR

task

force

established

major

and

minor

features

for

both

complete and incomplete aQpical fiactures

of

the femur''

(Table

I). All

of the major

features

should be

present

to

designate

a

fracture

as

atypicai aod distinguish it from more

common

os-

teoporotic hip

fiactures

(FiS.

2).

The minor

features

have

also

been

described

in

association

with

atypical

femoral

fractures,

but

they are not required for diagnosis.

Although

the ASBMR

criteria are usefrrl for defining atyp-

ical

femoral fractures and allowing

consistent diagnosis

across

studies,

some

features

remain

controversial. For

instance,

gener-

alized

cortical thickening

(one

of the

minor radiographic

features)

is

believed to result from an

impaired ability

of bone

to

remodel

because

of

prolonged

bisphosphonate use,

leading

to

an

accu-

mulation

of

microdamage and

compromised

bone

strength -'',

However,

a

recent study

by

our

group found that

prolonged

alendronate treatrnent

(>5

years)

did

not

cause

thickened femoral

cortjces'.. This result

suggested

that femoral cortices

in

patients

who have undergone

long-term

bisphosphonate treatrnent

may

have

already been

thick

prior

to the

initiation

of bisphosphonate

Dbclosure:

None of the authors

received

payments

or

services,

either directly

or

indirectly

(i.e.,

via his or

her

institution),

from

a

third

party

in

support

of

any

aspect of this

work.

One

or

moTe of

the authors,

or

his

or her

institution,

has

had

a

financial relationship, in the thirly-six months

pnor

to submission

of

this work,

with

an entity

in

the biomedical arena

that

could

be

perceived

to

influence

or

have

the

potential

to

influence what is written

in

this

work.

No

author has

had any

other relationships,

or

has

engaged

in

any

other activities, that could

be

perceived

to

influence

or

have

the

potential

to

influence

what

is

written

in

this work.

The

complete

Dlsclosur6

of Poter*lal Conf,lc,ts

of lntercst

submitted

by

authors

are

always

provided

with the online version

of

the

article.

J8one Joint SurgAm.2013;95:o8(1-13)

http//dX dOiOd

102106/JBIS.L00568