Distal phalanx fractures in horses a survey of 274 horses with radiographic assessment of healing in 36 horses


Honnas, C.M.; O'brien T.R.; Linford, R.L.

Veterinary Radiology 29(3): 98-107

1988


The case records of 274 horses with fractures of the distal phalanx were reviewed. Fifty-two horses had bilateral forelimb fractures, for a total of 326 distal phalanx fractures. The fractures were classified into one of five previously described types, based on the radiographic anatomic configuration of the fracture. Solar margin fractures, which have been briefly described in other reports and previously classified as type V fractures, were identified in 132 horses. This type of fracture is distinct from other distal phalanx fractures. Due to the high incidence of solar margin fractures, these fractures were classified as a separate type (type VI). Follow-up radiographic examinations to assess fracture healing were available for 36 horses. Twenty-two horses with distal phalanx fractures (three type I, nine type II, two type III, one type IV, one type V, and six type VI) had radiographic evidence of complete bony union of the fracture at a mean of 11 months after injury. Eight horses with conplete type II fractures involving the articular surface had bony union of the body and solar margin, but not the subchondral bone at the articular surface, a mean of 11 months after injury. Six horses (four type II and two type IV) had little radiographic evidence of bony healing during the follow-up period. All fractures that eventually healed had evidence of progression toward bony union by 6 months after injury.

DISTAL
PHALANX
FRACTURES
IN
HORSES
A
Survey
of
274
Horses
with
Radiographic
Assessment
of
Healing
in
36
Horses
CLIFFORD
M.
HONNAS,
DVM,
TIMOTHY
R.
O'BRIEN,
DVM,
PHD,
ROBERT
L.
LINFORD,
DVM,
PHD
The
case
records
of
274
horses
with
fractures
of
the
distal
phalanx
were
reviewed.
Fifty-two
horses
had
bilateral
forelimb
fractures,
for
a
total
of
326
distal
phalanx
fractures.
The
fractures
were
classified
into
one
of
five
previously
described
types,
based
on
the
radiographic
anatomic
configuration
of
the
fracture.
Solar
margin
fractures,
which
have
been
briefly
described
in
other
reports
and
previously
classified
as
type
V
fractures,
were
identified
in
132
horses.
This
type
of
fracture
is
distinct
from
other
distal
phalanx
fractures.
Due
to
the
high
incidence
of
solar
margin
fractures,
these
fractures
were
classified
as
a
separate
type
(type
VI).
Follow-up
radiographic
examinations
to
assess
fracture
healing
were
available
for
36
horses.
Twenty-two
horses
with
distal
phalanx
fractures
(three
type
I,
nine
type
II,
two
type
III,
one
type
IV,
one
type
V,
and
six
type
VI)
had
radiographic
evidence
of
complete
bony
union
of
the
fracture
at
a
mean
of
11
months
after
injury.
Eight
horses
with
complete
type
II
fractures
involving
the
articular
surface
had
bony
union
of
the
body
and
solar
margin,
but
not
the
subchondral
bone
at
the
articular
surface,
a
mean
of
11
months
after
injury.
Six
horses
(four
type
II
and
two
type
IV)
had
little
radiographic
evidence
of
bony
healing
during
the
follow-up
period.
All
fractures
that
eventually
healed
had
evidence
of
progression
toward
bony
union
by
6
months
after
injury.
Veterinary
Radiology,
Vol.
29,
No.
3,
1988;
pp.
98
-
107
Key
words:
distal
phalanx,
solar
margin,
bony
union,
radiology,
equine.
F
RACTURES
OF
THE
DISTAL
PHALANX
occur
in
all
breeds
of
horses
but
are
most
common
in
racing
Thoroughbreds
and
Standardbreds
and
working
Quarter
Horses.'
-3
The
causes
of
distal
phalanx
fractures
in
the
horse
include
racing
on
hard
uneven
surfaces,
foreign
body
puncture,
falling,
and
kicking
hard,
immovable
objects.
Predisposing
factors
include
osteo-
myelitis,
nutritional
deficiencies,
upright
conformation,
un-
balanced
shoeing,
and
laminitis.
2-
'
2
A
radiographic
classification
system
based
on
the
anatomic
location
of
the
fracture
has
been
used
to
categorize
distal
pha-
lanx
fractures
into
five
types
(Fig.
1).
5,6
Type
I
fractures
are
nonarticular
fractures
of
the
palmar/plantar
process
of
the
bone.
Type
II
fractures
are
articular
fractures
that
are
not
mid-
sagittal
and
extend
from
the
distal
interphalangeal
joint
to
the
solar
margin
of
the
bone.
Type
III
fractures
are
midsagittal
articular
fractures
that
divide
the
distal
phalanx
into
two
ap-
proximately
equal
parts.
Type
IV
fractures
are
extensor
pro-
cess
fractures.
Type
V
fractures
are
comminuted
fractures
or
fractures
secondary
to
foreign
body
penetration
or
osteomye-
litis.
There
have
been
few
reports
of
long-term
radiographic
follow-up
of
these
fractures.'
,
"
The
objectives
of
this
study
were
to
survey
the
prevalence
of
distal
phalanx
fractures
in
horses
admitted
to
the
University
of
California,
Davis,
between
1976
and
1986;
to
describe
and
classify
solar
margin
fractures
of
the
distal
phalanx,
which
have
From
the
Veterinary
Medical
Teaching
Hospital
(Honnas)
and
the
Departments
of
Radiological
Sciences
(O'Brien)
and
Surgery
(Linford),
School
of
Veterinary
Medicine.
University
of
California,
Davis,
CA
95616.
Direct
correspondence
and
reprint
requests
to
Timothy
R.
O'Brien,
DVM,
PhD,
Department
of
Radiological
Sciences,
School
of
Veterinary
Medicine,
Uni-
versity
of
California,
Davis,
CA
95616.
been
poorly
documented;
and
to
present
the
radiographic
find-
ings
of
long-term
follow-up
of
36
horses
with distal
phalanx
fractures.
Materials
and
Methods
The
case
records
of
274
horses
admitted
to
the
University
of
California,
Davis
between
1976
and
1986
with distal
phalanx
fractures
were
reviewed.
Each
horse's
signalment,
fracture
type,
fracture
location,
and
limb
or
limbs
involved
were
ex-
tracted
from
the
hospital
record
and
radiographic
examination.
Diagnosis
of
a
distal
phalanx
fracture
was
made
on
the
basis
of
clinical
and
radiographic
examinations.
Clinical
signs
in-
cluded
a
painful
response
to
hoof
testers,
lameness,
and
in-
creased
digital
pulses.
Occasionally
with
more
subtle
lame-
nesses,
perineural
anesthesia
of
the
palmar/plantar
digital
nerves
at
the
level
of
the
pastern
or
proximal
sesamoid
bones
was
required
to
localize
the
source
of
the
lameness.
Radio-
graphic
examination
of
the
affected
distal
phalanx
included
four
radiographic
views:
65°
dorsoproximal-
palmarodistal;
lateromedial
(LM);
65°
proximal
45°
lateral
-
palmaro-
distomedial
oblique;
and
65
°
proximal
45
°
medial
-
palmarodistolateral
oblique.'
2
On
the
basis
of
the
radiographic
interpretation,
these
fractures
were
divided
into
the
five
pre-
viously
described
fracture
types.
A
sixth
fracture
classification
was
created
to
describe
fractures
of
the
solar
margin
of
the
distal
phalax
(Fig.
2).
Long-term
radiographic
follow-up
was
obtained
when
possi-
ble.
Bony
healing
of
distal
phalanx
fractures
was
considered
complete
when
the
fracture
could
no
longer
be
identified
radio-
graphically.
For
descriptive
purposes
of
the
fracture
location,
98
Vol_
29,
No.
3
DISTAL
PHALANX
FRACTURES
IN
HORSES
99
TYPE
IV
.;
TYPE
I
1111
0
-
TYPE
V
TYPE
II
TYPE
III
FIG.
1.
Distal
phalanx
fractures,
types
I-V.
the
distal
phalanx
was
divided
into
three
regions:
(1)
solar
mar-
gin;
(2)
body;
and
(3)
articular
margin.
Results
Two
hundred
seventy-four
horses
were
admitted
to
the
Uni-
versity
of
California,
Davis
with
distal
phalanx
fractures
during
this
10-year
period.
Of
the
274
horses
reviewed,
52
horses
had
bilateral
distal
phalanx
fractures
in
the
forelimbs,
totaling
326
limbs
with
radiographically
identifiable
distal
phalanx
frac-
tures
(Table
1).
Quarter
horses
(117)
and
Thoroughbreds
(87)
were
the
predominant
breeds
affected.
There
were
153
geld-
ings,
86
females,
and
35
intact
males,
with
a
mean
age
of
7
years
(range,
1
month
to
26
years).
Fro.
2.
A
prominent
solar
margin
fracture
(type
VI)
identified
(arrows)
in
a
65°
dorsoproximal-palmarodistal
projection
of
the
distal
phalanx.
100
HONNAS
ET
AL
1988
TABLE
1.
Incidence
and
Location
of
326
Distal
Phalanx
Fractures
Identified
in
274
Horses
Fracture
type
1
II
III
IV
V
VI
Total
Incidence
No.
of
horses
31
50
10
43
8
132
274
Bilateral
2
3
0
2
1
44
52
Unilateral
29
47
10
41
7
88
222
Location
Forelimb
27
48
6
44
6
175
306
Hindlimb
6
5
4
1
3
1
20
Articular
53
10
45
108
Nonarticular
33
9
176
218
Twenty-nine
(33%)
horses
with
unilateral
type
VI
fractutes
had
no
identifiable
bony
abnormality
of
the
distal
phalanx
which
could
be
considered
as
a
predisposing
factor
to
fracture
(Fig.
3).
Ten
(11%)
horses
with
unilateral
type
VI
fractures
had
radiographic
signs
of
both
laminitis
and
pedal
osteitis
in
the
affected
distal
phalanx
(Fig.
4).
The
radiographic
signs
in
these
horses
consisted
of
a
hypervascular
pattern,
decreased
bone
opacity,
altered
hoof/pastern
axis,
and
reactive
bone
on
the
dorsum
of
the
distal
phalanx.
Eighteen
horses
(20%)
with
uni-
lateral
fractures
had
fractures
secondary
to
laminitis
without
evidence
of
pedal
osteitis,
and
26
horses
(30%)
had
fractures
associated
with
pedal
osteitis
without
signs
of
laminitis.
Three
horses
had
solar
margin
fractures
secondary
to
osteomyelitis,
one
as
a
result
of
foreign
body
penetration
and
one
secondary
to
flexural
deformity
of
the
distal
interphalangeal
joint.
Thirty-eight
(86%)
of
the
horses
with
bilateral
type
VI
frac-
tures
had
multiple
fracture
fragments
identified
in
both
front
feet.
Fractures
with
multiple
fragments
were
seen
in
associa-
tion
with
laminitis
and
palmar
rotation
of
the
distal
phalanx
(14
horses),
laminitis
without
palmar
rotation
of
the
distal
Fin.
3.
The
solar
margin
fracture
involving
the toe
has
the
appearance
of
an
acute
fracture.
There
is
no
identifiable
bony
abnormality
of
the
distal
phalanx
that
would
predispose
to
fracture.
A
ti
'
7
FIG.
4.
(A)
Pedal
osteitis
and
laminitis
are
apparent
on
the
65°
dorsoproximal—palmarodistal
projection,
as
evidenced
by
the
hypervascular
pattern
and
decreased
bone
opacity.
(B)
Type
VI
fractures
from
the
toe
region
can
often
be
identified
on
the
LM
projection.
102
HONNAS
ET
AL
1988
phalanx
(8
horses),
and
pedal
osteitis
(8
horses).
The
distal
phalanx
appeared
radiographically
normal
in
eight
horses
with
multiple
fracture
fragments.
Six
of
the
horses
with
bilateral
type
VI
fractures
had
single
fracture
fragments
identified
in
both
front
feet.
The
distal
phalanx
was
radiographically
nor-
mal
in
four
of
the
horses
with
single
bilateral
type
VI
fractures.
Pedal
osteitis
was
seen
in
association
with
the
fracture
in
the
remaining
two
horses
with
bilateral
single
fracture
fragments.
Long-term
radiographic
follow-up
was
obtained
in
36
(13%)
horses
at
a
mean
of
11
months
(range,
1-36
months)
after
injury
(Table
2).
Each
horse
had
only
one
fracture.
There
were
3
(8%)
type
I,
21
(58%)
type
II,
2
(6%)
type
III,
3
(8%)
type
IV,
1
(3%)
type
V,
and
6
(17%)
type
VI
fractures.
The
mean
age
of
these
horses
was
6
years.
The
involved
limbs
included
the
left
front
(15),
right
front
(15),
right
hind
(4),
and
left
hind
(2).
The
location
of
the
fractures
were
15
lateral,
15
medial,
2
sagittal,
and
3
extensor
process,
and
1
extending
transversely
from
the
lateral
quarter
to
the
medial
toe
region.
Twenty-seven
horses
were
treated
with
bar
shoes
and
clips
(3
with
concurrent
neur-
ectomy),
1
with
lag
screw
fixation,
and
8
with
other
methods
of
therapy
(Table
2).
Twenty-two
(61%)
fractures
(3
type
I,
9
type
II,
2
type
III,
1
type
IV,
1
type
V,
and
6
type
VI)
healed
by
bony
union
in
a
mean
of
11
months
after
injury.
Eight
type
II
(22%)
fractures
had
evidence
of
bony
healing
of
portions
of
the
fracture
involv-
ing
the
solar
margin
and
the
body
of
the
distal
phalanx,
but
not
the
subchondral
bone
at
the
articular
surface,
at
a
mean
of
11
months
after
injury.
Six
(17%)
fractures
(4
type
II
and
2
type
IV)
had
little
or
no
evidence
of
bony
healing
at
a
mean
of
10
months
(range,
5-24
months)
after
injury.
Lameness
examination
of
the
36
horses
revealed
14
of
22
(2
type
I,
6
type
II,
2
type
III,
1
type
IV,
and
3
type
VI)
with
radiographic
evidence
of
bony
union
were
sound
at
the
walk
and
trot.
Seven
of
the
22
horses
(1
type
I,
3
type
II,
1
type
V,
and
2
type
VI)
were
mildly
lame
at
the
trot.
Results
of
clinical
examination
were
unavailable
for
one
horse.
Lameness
evalua-
TABLE
2.
Fracture
Type,
Treatment,
Appearance
at
Last
Radiographic
Examination,
and
Outcome
of
Long-term
Follow-up
in
36
Horses
Case
Age
(years)
Fracture
type
Treatment
Radiographic
appearance
(time
at
examination
in
months)
Outcome
1
3
BSWC*
Healed
(4)
Soundt
2
5
BSWC,
pads
Healed
(17)
Sound
3
4
BSWC
Healed
(12)
Lame
4
10
II
BSWC
Healed
(8)
Lame
5
3
II
BSWC,
pads
Partial
(6)
Lame
6
10
II
Unknown
None
(24)
Unknown
7
3
II
BSWC,
neurectomy
None
(8)
Unknown
8
1
II
BSWC
Healed
(36)
Sound
9
6
II
BSWC
Partial
(5)
Unknown
10
3
II
BSWC,
neurectomy
Partial
(11)
Sound
11
1
II
BSWC
Healed
(16)
Lame
12
4
II
BSWC
None
(5)
Unknown
13
4
II
BSWC
Healed
(7)
Sound
14
4
II
BSWC
Partial
(12)
Refractured
in
race,
lame
15
10
II
BSWC
Partial
(8)
Lame
16
8
II
BSWC
Partial
(12)
Sound
17
6
II
1
year
rest
Healed
(12)
Lame
18
8
II
BSWC
Healed
(5)
Sound
19
13
II
BSWC,
pads
Healed
(10)
Sound
20
6
II
BSWC,
neurectomy
Partial
(10)
Lame
21
6
II
BSWC
Partial
(26)
Lame
22
4
II
BSWC
Healed
(8)
Sound
23
4
II
BSWC
None
(7)
Lame
24
6
II
BSWC
Healed
(16)
Sound
25
7
III
Lag
screw
fixation
Healed
(10)
Sound
26
2
III
BSWC
Healed
(8)
Sound
27
7
IV
Rest
None
(8)
Lame
28
1
mo.
IV
Fiberglass
cast
Healed
(1)
Sound
29
11
IV
Radiation
therapy
None
(7)
Sound
30
15
V
Currettage
Healed
(15)
Lame
31
1
VI
Wide
web
shoes
with
pads
Healed
(6)
Sound
32
2
VI
Bar
shoe
Healed
(11)
Lame
33
21
VI
Bar
shoe
Healed
(10)
Unknown
34
9
VI
Wide
web
shoes
with
pads
Healed
(21)
Lame
35
2
VI
Rest
Healed
(3)
Sound
36
6
VI
Rest
Healed
(16)
Sound
BSWC
=
bar
shoe
with
clips
and
rest;
sound
=
no
lameness
at
walk
or
trot.
VOL.
29,
NO.
3
DISTAL
PHALANX
FRACTURES
IN
HORSES
103
tion
of
eight
horses
with
partially
healed
fractures
revealed
that
two
horses
(type
II)
were
sound
at
the
walk
and
trot
and
five
horses
(type
II)
were
lame
at
the
walk
and
trot;
the
results
of
clinical
examination
were
unavailable
for
one
horse.
Evalua-
tion
of
lameness
in
the
six
horses
that
did
not
show
evidence
of
healing
revealed
that
one
horse
(type
IV)
was
sound
at
the
walk
and
trot
and
two
horses
(1
type
II
and
1
type
IV)
were
lame,
and
the
results
of
clinical
examination
were
unavailable
for
three
horses.
One
horse
(horse
23)
was
killed
7
months
after
sustaining
a
type
II
fracture
of
the
distal
phalanx
due
to
reasons
unrelated
to
the
distal
phalanx
fracture.
The
horse
had
been
treated
with
a
bar
shoe
and
quarter
clips.
Radiographically,
there
were
mild
resorptive
changes
of
the
entire
fracture
5
weeks
after
injury.
At
4
months,
the
fracture
was
still
prominent,
especially
in
the
subchondral
bone.
By
7
months,
there
was
narrowing
of
the
fracture,
with
progression
toward
bony
union.
Histologically,
there
was
bony
union
of
the
fracture
at
the
solar
margin
of
the
distal
phalanx
with
fibrous
union
at
the
body
and
articular
margin.
Articular-like
hyaline
cartilage
and
synovial
tissue
were
present
in
the
subchondral
area
of
the
fracture.
Discussion
Diagnosis
of
distal
phalanx
fractures
is
based
upon
clinical
and
radiographic
findings
that
include:
(1)
the
presence
of
lameness
at
a
walk
or
trot;
(2)
digital
pulses
and
heat
at
the
coronary
band
with
an
acute
fracture;
(3)
resentment
to
com-
pression
of
the
sole
and
wall
with
hoof
testers;
and
(4)
radio-
graphic
evidence
of
a
fracture.
4,8
The
clinical
signs
tend
to
be
more
apparent
in
horses
with
an
articular
fracture,
and
these
horses
also
show
a
generalized
increase
in
sensitivity
to
hoof
testers.
Clinical
signs
are
usually
less
apparent
for
nonarticular
fractures,
and
the
horse
may
be
painful
to
hoof
testers
only
over
the
area
of
the
fracture.
3
Perineural
anesthesia
of
the
palmar/
plantar
digital
nerves
may aid
in
the
diagnosis
of
some
frac-
tures.
The
differential
diagnoses
of
distal
phalanx
fractures
should include
sole
abscess,
bruised
sole,
pedal
osteitis,
navicu-
lar
bone
fracture,
navicular
disease,
foreign
body
penetration,
and
laminitis.
4,8
Radiographic
examination
usually
confirms
the
diagnosis
of
a
fracture
of
the
distal
phalanx.
If
a
fracture
is
not
identified,
but
the
clinician
believes
that
a
distal
phalanx
fracture
is
likely,
a
repeat
radiographic
examination
should
be
performed
in
10
14
days.
By
this
time,
bone
resorption
along
the
fracture
will
make
identification
of
the
fracture
more
likely.s•
8
Our
investigation
revealed
the
fracture
line
for
all
types
of
distal
phalanx
fractures
became
increasingly
wider
during
the
first
few
weeks
until
a
maximum
width
was
seen
at
4-6
weeks
after
injury.
Previous
reports
of
distal
phalanx
fractures
describe
the
type
II
fracture
as
the
most
common
type.
4-6
This
investigation
revealed
that
type
VI
fractures
were
more
common
(54%)
than
all
other
types
combined
(Table
1).
Type
II
fractures
were
the
second
most
common
type,
representing
16%
of
the
total
num-
ber
of
limbs
with
distal
phalanx
fractures.
In
this
series
of
274
horses,
306
fractures
occurred
in
the
forelimb,
whereas
only
20
fractures
occurred
in
the
hindlimb.
This
may
occur
because
the
front
limbs
bear
more
weight
than
the
hind
limbs
8
or
because
the
total
weight
of
the
horse
may
be
suspended
by
a
single
forelimb
at
the
gallop.
Usually
only
one
forelimb
is
affected,"
although
as
seen
in
this
series,
bilateral
fractures
do
occur.
Veterinary
practitioners
frequently
do
not
identify
solar
margin
fractures
because
of
inadequate
radiographic
tech-
nique.
Overexposure
for
evaluation
of
the
navicular
bone
re-
sults
in
an
inability
to
visualize
marginal
fracture
fragments.
A
reduction
in
the
radiographic
technique,
which
permits
evalu-
ation
of
the
solar
margin,
is
necessary
in
many
cases
to
identify
solar
margin
fractures.
Reducing
the
mAs
by
one-half
will
in-
crease
the
ability
to
visualize
bony
detail
at
the
solar
margin
and
make
identification
of
these
fractures
possible.
This
may
account
for
the
higher
incidence
of
type
VI
fractures
identified
in
this
study,
compared
with
previous
reports.
5,8
Fracture
of
the
solar
margin
has
been
reported.'•'"°"
15
Due
to
the
large
number
of
solar
margin
fractures
identified
in
this
study,
we
propose
the
addition
of
a
type
VI
fracture
to
separate
this
fracture
from
type
V
fractures.
Type
V
fractures
previously
included
all
comminuted
or
pathologic
fractures
secondary
to
osteomyelitis
or
foreign
body
penetration.
8,8
We
believe
that
solar
margin
fractures
are
a
separate
entity
from
type
V
frac-
tures
because
they
involve
only
the
solar
margin
and
not
the
body
of
the
distal
phalanx.
However,
type
VI
fractures
can
result
from
foreign
body
penetration
or
osteomyelitis
and
can
be
comminuted.
We
suggest
that
type
V
fractures
include
all
fractures
of
the
body
of
the
distal
phalanx
not
described
by
types
I
IV
and
VI.
In
this
series
of
176
solar
margin
fractures,
41
horses
had
no
radiographic
evidence
of
other
bony
abnormalities
of
the
distal
phalanx.
Traumatic
insult
from
a
localized
force
has
been
sug-
gested
as
the
cause
of
solar
margin
fractures
in
apparently
healthy
bone."
In
this
investigation,
52
horses
were
found
to
have
bilateral
forelimb
fractures.
Forty-four
horses
(85%)
with
bilateral
forelimb
fractures
had
solar
margin
fractures
(Table
1).
Thirty-two
of
the
bilateral
type
VI
fractures
were
associated
with
laminitis,
pedal
osteitis,
or
a
combination.
The
majority
(62%)
of
horses
with
unilateral
solar
margin
fractures
also
suf-
fered
from
laminitis,
pedal
osteitis,
or
both
conditions.
Abnor-
malities
of
the
distal
phalanx,
such
as
laminitis
and
pedal
os-
teitis,
appear
to
play
a
significant
role
in
the
incidence
of
these
fractures.
These
disease
processes
often
result
in
resorption
of
the
solar
cortex,
which
may
weaken
the
solar
margin,
leading
to
the
high
prevalence
of
type
VI
fractures
seen
in
this
series.
Radiographic
signs
of
decreased
bony
opacity
and
increased
coarseness
to
the
bony
pattern
at
the
solar
margin
would
sup-
port
this
idea.
Type
VI
fractures
healed
by
bony
union
in
all
six
horses
followed
radiographically
in
this
study
(Fig.
5).
We
observed
that
resorption
of
type
VI
fracture
fragments
can
occur,
al-
though
this
was
not
apparent
in
this
series.
A
scalloped
solar
margin
of
the
distal
phalanx
occurs
following
resorption
of
these
fractures.
A
B
FIG.
5.
(A)
Solar
margin
fractures
(arrows)
are
identified
on
the
6Y
dorsoproximal—palmarodistal
projection
of
the
distal
phalanx.
(B)
The
fractures
are
no
longer
identified
at
6
months,
and
the
solar
margin
has
retained
its
original
contour,
indicating
bony
union.
VoL.
29,
No.
3
DISTAL
PHALANX
FRACTURES
IN
HORSES
105
Treatment
of
distal
phalanx
fractures
most
often
entails
cor-
rective
shoeing
and
long
rest
periods
4
or
internal
fixation
of
selected
fractures
(types
II,
III,
or
IV)
that
have
an
articular
component.
8,
'
3
'
16-18
Corrective
shoeing
consists
of
a bar
shoe
with
quarter
clips,
which
is
aimed
at
limiting
hoof
expansion
to
help
counteract
shear
forces
across
the
fracture.
Many
horses
walk
with
little
or
no
perceptible
lameness
shortly
after
correc-
tive
shoes
are
placed
on
the
affected
foot,
despite
the
lack
of
fracture
healing.
This
improvement
in
gait
is
attributed
to
the
stabilization
of
the
fracture
afforded
by
the
bar
shoe
and
clips.
We
emphasize
that
treatment
should
continue
even
in
the
ab-
sence
of
lameness
until
there
is
radiographic
confirmation
of
bony
union.
Conservative
therapy
has
been
reported
to
require
rest
pe-
riods
ranging
from
3
to
19
months
for
complete
bony
union
of
the
fracture.
4,7,8,16,
"
,
'
9
The
results
of
conservative
treatment
for
35
of
the
36
horses
in
this
series
indicate
that
the
majority
of
fractures
will
heal
(21
cases)
or
will
make
significant
progress
toward
healing
(8
cases),
in
a
mean
of
11
months
after
injury
(Table
2).
All
of
the
fractures
that
healed
partially
or
totally
had
radiographic
evidence
of
healing
by
6
months
after
injury.
Six
horses
did
not
show
any
evidence
toward
healing,
at
a
mean
of
10
months
after
injury.
Therefore,
we
believe
that
if
there
is
no
radiographic
evidence
of
healing
(i.e.,
increased
density
and
diminished
clarity
of
the
fracture
line)
by
6
months
after
in-
jury,
then
the
prognosis
for
eventual
bony
union
of
the
fracture
is
guarded.
Definitive
recommendations
for
the
treatment
of
distal
pha-
lanx
fractures
can
be
made
only
in
light
of
the
economic
worth
of
each
individual
horse,
the
intended
use
of
the
horse,
and
the
specific
type
of
fracture
radiographically
identified.
In
general,
we
recommend
that
type
I
and
II
fractures
be
treated
with
bar
shoes,
clips,
and
rest.
Failure
to
respond
to
corrective
shoeing
is
an
indication
for
neurectomy
in
certain
cases.
Horses
with
chronic
type
I
fractures
that
are
persistently
lame
may
be
treated
with
palmar
digital
neurectomy
if
perineural
anesthesia
of
the
palmar
digital
nerves
relieves
the
lameness.'
4
The
ana-
tomic
location
of
type
II—
VI
fractures
and
the
development
of
secondary
joint
disease
in
horses
with
articular
fractures
may
preclude
treatment
by
palmar
digital
neurectomy,
due
to
in-
nervation
supplied
by
the
dorsal
branch
of
the
palmar
digital
nerve.
Type
III
fractures
can
be
treated
either
conservatively
(bar
shoes
and
clips)
or
surgically
(lag
screw
fixation).
Lag
screw
fixation
provides
rigid
stability
and
alignment
of
the
articular
margin,
which
minimizes
articular
incongruity
and
thereby
lessens
the
likelihood
of
secondary
joint
disease
at
the
distal
interphalangeal
joint."
Internal
fixation
may
result
in
shorter
total
healing
times,
ranging
from
3
weeks
to
9
months.'
3,
"
In
this
series,
two
horses
had
type
III
fractures.
One
horse
was
treated
with
interfragmentary
compression
and
another
was
treated
with
a
bar
shoe
and
clips
(Table
2).
The
fractures
healed
in
10
months
and
8
months,
respectively,
and
both
horses
were
sound.
A
serious
complication
of
internal
fixation
is
infection
at
the
surgical
site
and
the
development
of
osteomyelitis.
8
Ad-
ditional
considerations
when
contemplating
internal
fixation
versus
conservative
management
include
increased
cost
for
surgery,
the
more
intense
management
and
technical
skills
required,
and
the
final
outcome,
which
may
be
comparable
when
managed
with
either
method.
Treatment
of
type
IV
fractures
may
involve
rest,
internal
fixation,"
or
surgical
removal.
20
Type
V
fractures
are
best
treated
with
bar
shoes
and
clips,
and
with
curettage
if
the
frac-
ture
is
secondary
to
osteomyelitis.
Treatment
of
type
VI
fractures
involves
the
same
principles
as
treatment
of
other
fracture
types,
but
it
can
become
compli-
cated
in
the
presence
of
laminitis.
In
these
cases,
treatment
should
be
directed
first
at
stopping
the
progression
of
the
la-
minitis
first
and
then
at
treating
the
solar
margin
fracture.
Corrective
shoeing,
utilizing
a
wide
web
shoe
and
pads,
appears
to
help
alleviate
the
pain
associated
with
fracture
in
these
cases.
Fractures
seen
in
a
normal-appearing
distal
phalanx
or
in
asso-
ciation
with
pedal
osteitis
should
also
be
treated
with
corrective
shoeing
and
rest.
Theoretically,
shear
forces
across
the
fracture
may
be
less
for
type
VI
fractures
than
for
other
types
of
distal
phalanx
fractures;
therefore,
strict
immobilization
may
not
be
required
for
healing
to
occur.
As
seen
in
this
series,
healing
will
occur
with
rest
alone
(Table
2).
Surgical
removal
of
fracture
fragments
has
been
reported,'°
,
'
5
although
our
experience
indi-
cates
this
may
not
be
necessary.
Although
type
VI
fractures
heal
and
the
affected
horses
may
become
sound,
laminitis may
diminish
the
postfracture
level
of
performance.
This
investigation
revealed
that
nonarticular
fractures
treated
conservatively
have
a
better
prognosis
for
bony
union,
compared
with
articular
fractures
(Table
3).
This
may
be
the
result
of
the
middle
phalanx
causing
continued
movement
of
the
fracture
during
weight-bearing,
thereby
slowing
healing
of
articular
fractures.
In
addition,
we
speculate
that
articular
frac-
tures
managed
conservatively
may
heal
slower
because
of
disruption
of
the
articular
cartilage
and
subsequent
filling
of
the
fracture
with
synovial
tissue
and
fluid.
Continued
weight-
bearing
may
force
synovial
fluid
into
the
fracture,
causing
fur-
ther
distraction
of
the
fragments.
This
could
account
for
the
normal
progression
of
healing
of
distal
phalanx
fractures
seen
in
this
study.
We
observed
bony
union
appeared
to
start
at
the
solar
margin
and
progress
toward
the
articular
margin
(Fig.
6).
Although
it
appeared
that
articular
fractures
heal
at
the
same
rate
as
non-articular
fractures,
it
is
important
that
only
46%
of
TABLE
3.
Number
of
Fractures
Healed
by
Complete
Bony
Union,
Time
to
Bony
Union,
and
Soundness
of
Horses
with
Articular
and
Nonarticular
Fractures
Articular
fractures
(types
II,
III,
and
IV)
Nonarticular
fractures
(types
I,
V,
and
VI)
No.
of
horses
26
10
Healed
(bony
union)
12
(46%)
10
(100%)
Mean
time
to
bony
union
(months)
I
I
11
Sound
at
walk
and
trot
12
(46%)
5
(50%)
:.•
M..i 4
•""•
:11
*ir
B
FIG.
6.
65°
proximal
45°
lateral—palmarodistomedial
oblique
view
of
the
distal
phalanx.
Type
H
distal
phalanx
fracture
(A)
at
initial
presentation
and
(B)
1
year
later.
Note
the
progression
of
healing
from
the
solar
margin
toward
the
articular
margin.
VoL.
29,
No.
3
DISTAL
PHALANX
FRACTURES
IN
HORSES
107
the
articular
fractures
healed
completely
in
the
follow-up
pe-
riod,
compared
with
100%
of
the
nonarticular
fractures.
Al-
though
our
study
revealed
that
only
half
of
both
groups
re-
turned
to
soundness,
nonarticular
fractures
may
have
a
better
prognosis
for
athletic
soundness
than
articular
fractures,
be-
cause
nonarticular
fractures
are
not
usually
associated
with
secondary
joint
disease.
Soundness
was
defined
as
the
absence
of
lameness
at
the
walk
or
trot.
Four
of
the
10
horses
with
nonarticular
fractures
had
solar
margin
fractures
associated
with
laminitis.
Although
the
solar
margin
fractures
healed
in
these
cases,
the
residual
lameness
in
two
of
these
horses
may
have
been
a
result
of
chronic
laminitis.
No
correlation
can
be
made
between
fracture
healing
and
soundness,
because
some
horses
returned
to
soundness
despite
lack
of
healing
and
others
remained
lame
in
the
presence
of
a
healed
distal
phalanx
(Table
2).
The
prognosis
for
mature
horses
with
distal
phalanx
frac-
tures
to
return
to
athletic
performance
is
guarded.'
,3
In
most
cases,
the
fracture
configuration
influences
the
prognosis
for
future
athletic
soundness.'
4
In
one
study,
50%
of
the
horses
with
type
II
fractures
returned
to
racing
performance.
8
Only
two
horses
with
type
II
fractures
in
this
series
returned
to
rac-
ing.
One
horse
refractured
the
distal
phalanx
in
a
race
3
weeks
following
removal
of
the
bar
shoe
and
clips
(Table
2).
For
this
reason,
we
advocate
supporting
a
healed
distal
phalanx
frac-
ture
with
a
corrective
shoe
for
the
performance
life
of
the
horse.
6
Horses
older
than
3
years
of
age
with
articular
distal
phalanx
fractures
do
not
heal
the
fracture
as
quickly
as
younger
horses,
and
previous
reports
have
recommended
internal
fixation
of
these
fractures
in
older
horses.'
3
'
16
'
19
Bony
healing
of
articular
fractures
after
conservative
therapy
has
been
reported
to
take
3
-9
months
in
horses
younger
than
3
years
of
age.'
6
"
Articu-
lar
and
nonarticular
distal
phalanx
fractures
heal
rapidly
in
foals
and
have
a
good
prognosis
for
return
to
soundness
when
treated
with
conservative
means
alone.'
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JV,
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TS,
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RM,
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Fractures
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pha-
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1986;189:550-4.
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Frank
ER.
Fracture
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In:
Veterinary
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1964:117.
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OR.
Lameness
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1974:241,
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Yovich
JV,
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BJ,
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EA,
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M,
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MH.
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EA,
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M,
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MH,
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PF,
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the
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phalanx
in
a
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DB,
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the
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