Realignment of P3 - the basis for treating chronic laminitis
Reprinted with permission from Equine Veterinary Education (EVE).
Original published in Equine Veterinary Education Vol 8 August 2006.
S. E. O'GRADY
Northern Virginia Equine, 8170 Patrickswell Lane, Marshall, Virginia 20198, USA.
Chronic laminitis is a frustrating, and often disheartening,
condition to manage. The biggest challenge to the veterinarian
and the farrier is to improve function in a foot that has
substantial and possibly permanent structural changes. Among
these is displacement of the distal phalanx (P3), the underlying
problem responsible for the clinical hallmarks of chronic laminitis:
chronic lameness, recurrent foot abscesses and abnormal hoof
wall growth (Hood 1999a; Morgan et al. 1999; Pollitt 1999).
Rotation of P3 is the most common form of displacement
and has several clinically important consequences. With
rotation, weight bearing is thought to be concentrated at the
apex of the distal phalanx, which predisposes the foot to focal
pressure on the solar corium in that area. Pain is the most
obvious and most urgent consequence. Ischaemia of the solar
corium (and probably of the tip of P3) is also an important
sequela, as it retards sole growth (Redden 1997; Hood 1998).
In addition to causing further damage to the laminar
attachments by the lever effect of the dorsal hoof wall on the
lamellae, rotation of the distal phalanx is thought to lead to
excessive pressure on the coronary corium by the extensor
process. The resulting ischaemia alters the rate and, in severe
cases, the direction of horn growth from the coronary papillae in
this area (Pollitt 1995; Hood 1999b). These problems can be
ameliorated only by restoring the alignment of the distal phalanx
relative to the bearing surface of the foot (i.e. to the ground
surface) and significantly reducing the forces of the DDFT.
2. Capsular vs. phalangeal rotation
When discussing rotation of the distal phalanx, it is important to
make the distinction between capsular and phalangeal rotation.
In horses with capsular rotation the hoof capsule diverges from
the dorsal surface of the distal phalanx. The alignment of the
distal phalanx in relation to the other phalanges may, or may
not, be relatively normal in these feet. In horses with phalangeal
rotation, the distal phalanx is displaced in relation to the long
axis of the first and second phalanges - i.e. there is an abnormal
degree of flexion in the DIP joint at rest (O'Grady 2002).
Phalangeal rotation indicates functional shortening of the deep
digital flexor musculotendinous unit.
In horses with capsular rotation and relatively normal
longitudinal alignment of the distal phalanx, realignment of
the distal phalanx relative to the ground is easily achieved with
trimming and shoeing alone. Horses with significant
phalangeal rotation may benefit from a surgical release
procedure (deep digital flexor tenotomy or inferior check
ligament desmotomy). A release procedure is generally
necessary to facilitate alignment of the distal phalanx and
improve patient comfort. Further indications for a tenotomy or
desmotomy is severity of the pain, chronicity, severity of the
rotation and how much sole depth is present. Trimming and
shoeing alone is often inadequate in many of these horses.
The severity and chronicity of the phalangeal rotation
dictates which procedure (tenotomy or desmotomy) should be
performed. Typically, more marked change in the angle of the
DIP joint is achieved with tenotomy than with desmotomy.
When a surgical release has been considered necessary for
laminitis cases, deep flexor tenotomy is the procedure used
most often. This author prefers to perform surgery after
applying the shoe.
3. Basis for treating chronic laminitis
Therapeutic trimming and shoeing has long been the mainstay
of treatment for chronic laminitis, and will continue to be
crucial for effective management. However, the principles
must be thoroughly understood and skillfully applied. The
objective is to restore the distal phalanx to its proper
orientation in relation to the ground, and restore the normal
phalangeal axis. Realigning the distal phalanx by reducing the
horn heel height extends the weight bearing surface of the
foot palmarly. However, realignment increases the forces
within the DDFT, and therefore, it is necessary to elevate the
heels to compensate for the loss of heel horn height.
Several different methods may be used to achieve this
goal. However, the effectiveness of many conventional
techniques is limited by inadequate sole depth and, even,
prolapse of the sole in a foot with significant distal phalanx
rotation, and by individual foot conformation (e.g. inadequate
heel mass in horses with underrun heels).
If inadequate hoof wall is available to accomplish
realignment, glue-on shoe technology is ideal for this purpose. Attaching the shoe using a polymethylmethacrylate has some
important advantages over conventional shoeing techniques
in horses with chronic laminitis. The procedure is atraumatic,
as it eliminates the need for nails. But equally important, it
allows the veterinarian or farrier to adjust the angle of the
shoe in relation to the foot (and thus to the solar margin of
the third phalanx) with precision, so the technique can easily
be tailored to the specific conformation and requirements of a
particular foot. This paper describes the technique used for
restoring the alignment of the distal phalanx with glue-on
shoes in horses with chronic laminitis.
4. Principles of application
When managing chronic laminitis, it appears to make little
difference which shoeing system is used, as long as the
method achieves the following goals:
- Re-establish weight bearing along the entire solar surface of
distal phalanx (rather than being concentrated at the apex)
- Reposition breakover by moving the functional breakover
- Decrease tension in the deep digital flexor tendon (DDFT)
- Recruit additional ground surface for weight bearing using a silastic polymer material
In the method described below, these 3 goals are achieved
by trimming the heels, applying a shoe that places the
functional breakover point near the apex of the distal phalanx,
glueing the shoe to the foot such that the shoe and solar
margin of the distal phalanx are parallel relative to the ground
with at least 15 mm of depth in-between, and raising the
heels using wedge-shaped rails attached to the shoe.
Trimming the heels and applying the shoe as described
below restores a more normal orientation of the distal phalanx
relative to the ground, and hence more normal loading of the
solar surface of the distal phalanx. Moving the breakover
palmarly decreases the moment arm exerted on the distal
interphalangeal joint (DIP), and therefore it is thought to
decrease tension on the dorsal lamellae. Removing more wall
at the heels than at the toe during realignment increases the
forces within the DDFT. This increase in DDFT can be partially
mitigated by moving breakover palmarly. Therefore, moving
the functional breakover point more palmarly is an important
element of this procedure.
Decreasing tension in the DDFT is achieved by
subsequently raising the heels using rails or by using a shoe
where the heels of the shoe are thickened relative to the toe.
The height of the rails of heels of the shoe are determined by
the amount of heel horn removed from the foot, sufficient
height of the rails necessary to encourage heel first landing
and how comfortably the horse moves. By diminishing the pull
of the DDFT on the distal phalanx and associated tissues, this
part of the procedure reduces tension on the dorsal laminae
and focal pressure on the solar and coronary corium. It
therefore reduces pain, limits further laminar damage, and
makes way for more normal perfusion and horn growth.
Pain relief is important, not just from a humane
perspective but because it interrupts the vicious cycle of pain
and increased tension in the deep flexor unit which is one of
the great challenges of managing these cases effectively.
Raising the heels following realignment of the distal phalanx
yields better results, in terms of comfort and hoof growth,
than simply realigning the distal phalanx.
A commercially available rail shoe is a convenient and
effective means of raising the heels in these horses.
Alternatively, a rail shoe can be made from a standard
aluminium shoe by welding or glueing a pair of wedge-shaped
rails to the ground surface of the shoe (see below). As well as
being necessary for realignment, trimming the heels maximises
the weight-bearing capacity of the heels, since shorter heels
are stronger and less likely to contract than long heels, and it
helps to move the weight bearing surface of the foot more
To further increase the bearing surface in the palmar portion
of the foot, the area between the branches of the shoe is filled
with an elastic, yet resilient, silastic polymer material. In this way,
the entire ground surface in the palmar 50-60% of the foot
(including sole, frog, and bars) is used to distribute the load.
These corrective procedures should not be implemented in
the chronic laminitic case until the condition is stable, i.e. the
coffin bone is stable but out of alignment vs. unstable where
the bone is still actively displacing, the laminae are still tearing
and the sole corium beneath is still being compressed. The
horse should be relatively comfortable on minimal medication
with no further radiographic evidence of further rotation for
at least 10 days and supportive therapy commenced in the
acute stage should be continued.
5. Materials and methods
The following materials are needed:
- Lateral radiograph of the foot (see below)
- Aluminium shoe and 2 wedge-shaped rails (see below)
- Denatured alcohol
- Equilox1 or similar composite material
- Two pieces of fibreglass mesh, 10 x 10 cm (4 x 4 in)
- Nonsterile gloves (e.g. latex examination gloves)
- Plastic wrap (sufficient to cover the foot)
- Silastic polymer (e.g. Equilox Pink)1
- (Plastic) gutter guard (to hold the silastic polymer in place)
A high-quality lateral radiograph that shows both soft
tissue and bone detail is critical to the success of this
technique. The area of primary interest is the solar margin of
the distal phalanx. The radiograph should therefore be taken
with the x-ray beam directed horizontally at a point
approximately 1 cm above the bearing surface of the wall,
midway between heel and toe. A radiopaque marker on the
upper surface of the wooden positioning block should be used
to represent the ground surface in unshod feet. A thumb tack
should be placed at the apex of the frog as a radiographic
landmark. As the tack is removed, a notch is created in the frog with a the hook of a hoof knife, which can then be used
as a reference point when fitting the shoe.
Aluminium shoes are lighter than steel, easy to shape, and
bond well to the composite. A wide web aluminium shoe can
be squared off and either rounded or beveled at the toe to set
the breakover point back as far as necessary. The shoe should
be of sufficient size and when fitted the branches extend at
least 1.5 cm beyond the heels. Sizing and fitting the shoe this
way increases the weight-bearing surface of the foot and
moves it more palmarly.
Unless a commercial rail shoe2 or a shoe with a thickened
heel is used, wedge-shaped strips of aluminium (rails) are
glued to each shoe branch to elevate the heels. The rail is
glued along the axial border of the shoe branch, on the
ground surface of the shoe (Fig 1). Note: the rails are applied
after the shoe is shaped to fit the trimmed foot.
|Fig 1: An inexpensive wide web aluminum shoe with rails attached using composite.
||Fig 2: Schematic drawing of measurements for realignment. Line 1 is drawn parallel and about 15 mm distal to the solar surface of P3. Line 2 is drawn parallel and approximately 15-18 mm dorsal to the parietal surface of the distal phalanx. Point A at the intersection of lines 1 and 2 is the point where the toe of the shoe should be set. Point B is approximately 6 mm dorsal to the dorsal margin of P3 and the point of breakover.
The procedure essentially involves trimming the heels and
attaching the shoe in such a way that the shoe is parallel with
the solar margin of the distal phalanx. In a foot with significant
phalangeal rotation, there will inevitably be some divergence of
the shoe from the bearing surface of the hoof in the toe area.
Before applying the shoe, it is necessary to determine what the
relationship between the hoof and the shoe will be when the
shoe is positioned parallel with the solar margin of the distal
phalanx. The lateral radiograph is used to guide trimming of
the hoof and alignment of the shoe (Fig 2; Parks 2003).
First, a line is drawn 20 mm distal to, and parallel with, the
solar margin of the distal phalanx (line 1); this is the plane to
which the ground surface of the foot should be trimmed. Any
horn at the heels and quarters that extends below this line is
removed before the shoe is applied. A distance of 20 mm is
required to ensure an adequate distance between the solar
margin of the distal phalanx and the ground surface.
Next, a line is drawn 15-18 mm dorsal to, and parallel
with, the dorsal surface of the distal phalanx (line 2). Where
lines 1 and 2 intersect (point A) is the dorsal-most point that
the shoe should be positioned relative to the ground surface
of the foot, although it may be positioned more palmarly.
Lastly, a short line is drawn from the tip of the third
phalanx to meet line 1; this line should be perpendicular to
line 1 (rather than vertical). A mark (point B) is made at the
ground surface approximately 6 mm dorsal to where these
lines intersect; this is the preferred location for breakover
Alternatively, a vertical line can be drawn from the apex of
the third phalanx and a mark made where that line meets the
ground surface of the foot (Page 1999). In most cases, both
methods place point B in approximately the same location. To
guide shoe placement, a mark is then made on the sole of the
foot to indicate the location of point B, using the notch in the
apex of the frog as a reference point.
When there is significant phalangeal rotation, which for
this paper is defined as 10° or greater, line 1 and the bearing
surface of the hoof will diverge, creating a wedge-shaped gap
at the toe. The distance between the bearing surface of the
hoof and line 1 (which represents the inner surface of the
shoe) indicates how much composite will be required to fill the
gap between the shoe and the hoof. This space should be at
least 15-20 mm.
When bonding the shoe to the foot, the composite will not
extend further forward than the apex of the frog, so only the
caudal part of the gap will be filled. It is useful to measure the
distance between line 1 and the bearing surface of the foot at
the apex of the frog (thumb tack) on the lateral radiograph.
This measurement indicates how thick the composite should be
at its widest point when bonding the shoe to the foot.
Prepare the foot and apply the shoe as follows:
|Fig 3: The shoe is pressed into the composite until the angle predetermined on the radiograph is achieved.
- Trim the bearing surface of the foot to match line 1 (i.e.
remove the horn that extends below line 1 on the
radiograph). If possible, trim down to solid horn; explore
any tracts or areas of hoof wall separation before applying the composite. With severe phalangeal rotation and no
appreciable sole depth, trimming the heels to realign P3
with the ground surface will result in an unlevel bearing
surface (i.e. bearing surface at the heels and quarters on a
different plane from the bearing surface at the toe). This is
not a problem, as the shoe does not need to contact the
bearing surface at the toe, and the composite will fill in
and negate the change of angle.
- Shape and fit the shoe to the foot.
- Cut a piece of (plastic) gutter guard to match the size of
- Prepare the composite (85-115 g, depending on the size
of the foot) according to the manufacturer's directions.
Wear gloves when working with the composite.
- Attach the rails to the shoe using approximately 28 g of
- Take each square of fibreglass mesh, cut the two borders
and tease it apart to separate the fibres; keep the two piles
of fibres separate. Mix an equal amount of composite with
each pile of fibreglass; roll each pile of compositefibreglass
mix into a solid cylindrical or tubular structure.
- Clean the trimmed area of hoof and matching surface of
the shoe with denatured alcohol; allow to dry completely.
- Apply a thin layer of plain composite to the bearing
surface of the wall, from frog apex to heel; work it into the
- Place a composite-fibreglass roll along the bearing surface
of the hoof wall on each side of the foot, beginning at the
apex of the frog and extending back beyond the heels.
- Place the shoe with gutter guard over the composite rolls,
using the mark made on the sole to guide shoe
placement. Note: the gutter guard is placed between the
hoof and the shoe.
- Press the shoe into the composite until the angle between
hoof and shoe determined on the radiograph is achieved
(Fig 3). In most cases, the shoe will be separated from the
hoof by only a thin layer of composite at the heels but by
several millimetres of composite at the level of the frog
apex. Take care to ensure good lateral-medial balance when
setting the shoe into the composite. Divergence of the shoe
from the hoof results in a space between shoe and hoof at
the toe. This configuration is to be expected in a foot
with significant phalangeal rotation, as the shoe is
positioned to be parallel with the solar margin of the third
phalanx, rather than with the hoof. In addition to restoring
the third phalanx alignment, it unloads the laminar and solar
corium at the toe, and it prevents contact between the shoe
and the sole in this area. Having premeasured the distance
between line 1 and the bearing surface of the hoof at the
frog apex on the radiograph is very helpful during this step.
- Cover the foot with plastic wrap and continue to hold the
foot off the ground until the composite cures, which
usually takes 2-3 mins. Then remove the plastic and set
the foot down.
- Mix the silastic polymer and apply it to the solar surface of
the foot (from dorsal to the frog apex to the heels) to fill
the space under the toe and the shoe branches. Press it
into the gutter guard to hold it in place.
In horses with bilateral laminitis, the same procedure is
performed on the opposite foot. As mentioned above, if a
surgical release procedure is deemed necessary, it is performed
after the shoe is applied.
The horse should be confined to a stall for the first 3 weeks.
Short periods of hand walking can begin after this time.
Nonsteroidal anti-inflammatory drugs are administered as
needed. In most cases the shoes are reset every 4-5 weeks.
The shoe is easily removed using hoof nippers, beginning with
one or two 'bites' through the composite at the heels.
The rails are lowered at each reset; typically rail shoes are
needed for only 2 or 3 shoeings. This glue-on system is
continued until there is sufficient hoof wall growth for
alignment of P3 to be maintained just with trimming and
Records were reviewed for 47 horses with chronic laminitis in
which this technique was used. In all cases, the condition had
been present for >3 months, there was >10° of P3 rotation, the
hoof tester response was positive, and lameness severity at least
Obel Grade II on a scale from I (mild) to IV (severe). All horses
underwent the above procedure for realignment of the third
phalanx. In addition, deep flexor tenotomy was performed on 14
horses and inferior check desmotomy on 2 horses that had
significant phalangeal rotation.
At the first reset (5 weeks after the shoes were first
applied), lameness was decreased at least one grade, hoof
tester pain was absent, and there was a notable increase in
sole thickness and hoof wall growth at the toe in all 47 horses.
The average increase in sole thickness was 3-5 mm. By the
third reset, hoof wall and sole growth were sufficient for
continued realignment of P3 to be accomplished simply by
trimming the hoof capsule. At this and subsequent resets, the
shoes were attached in a conventional manner using nails.
No adverse effects of the procedure have been noted to
date. In all cases the lameness was sufficiently improved that
controlled turnout could be tolerated. Of the total, 30 horses
(63.8%) returned to some level of usefulness, although below
their former level of athletic ability. The 2 cases that underwent
inferior check desmotomy were in this group. The remaining
17 horses (36.2%) were pasture sound. The 14 cases that
underwent deep flexor tenotomy were in this group.
This glue-on technique for shoeing chronically laminitic horses
is quick, simple, atraumatic, inexpensive and logical. Using
radiographic guidance, the shoe is bonded to the foot in a
manner that realigns the third phalanx relative to the ground
surface. By also raising the heels, this approach decreases
tension in the DDFT and along with the appropriate breakover
is thought to minimise tension and leverage on the dorsal
hoof wall during breakover, and relieves focal compression of
the solar and coronary corium, which in turn reduces pain and
promotes horn growth. This procedure is more effective and
allows greater flexibility and precision in realigning the third
phalanx than any other technique I have used. It can be tailored to the specific requirements of each foot simply by
using more or less of the composite as needed.
The importance of having a good lateral radiograph from
which to work cannot be overstated (Fig 4). Without a lateral
radiograph, it is impossible to determine the precise orientation
of the distal phalanx, and thus the degree of intervention
necessary to realign the third phalanx with the ground surface.
The primary reason this glue-on shoeing technique may be less
than satisfactory in inexperienced hands is failure to achieve
the desired angle between the shoe and the hoof, and thus
realignment of the third phalanx along with failure to relieve
DDFT tension. This mistake can be avoided by studying the
lateral radiograph and deciding how to orient the shoe in
relation to the bearing surface of the hoof before commencing.
|Fig 4: Radiographs indicating before and after realignment.
Although few of the horses with chronic laminitis returned
to their former level of athletic use, all horses treated with this
technique have become more comfortable. All are at least
pasture sound and able to move about freely with minimal
analgesic medication. In many of the laminitic horses treated in
this practice, permanent vascular and structural damage within
the foot prevents full recovery, regardless of which technique
is used to realign the third phalanx and support the foot.
In summary, effective management of chronic laminitis
involves restoring the alignment of the third phalanx relative
to the ground surface. Clinical experience has shown the glueon
shoeing technique described here to be a simple and
atraumatic method of effectively realigning the distal phalanx,
and thus improving comfort and hoof growth in horses with
- 1 Equilox International, Pine Island, Minnesota 55963, USA.
- 2 Nanric, Inc., Versailles, Kentucky 40383, USA.
- Hood, D.M. (1998) Treatment of chronic laminitis,
- in Proceedings of the Dodson and Horrell International Conference on Laminitis. pp 7-15.
- Hood, D.M. (1999a) Laminitis in the horse.
- Vet. Clin. N. Am.: Equine Pract. 15, 287-294.
- Hood, D.M. (1999b) The mechanisms and consequences of structural failure of the foot.
- Vet. Clin. N. Am.: Equine Pract. 15, 437-461.
- Morgan, S.J., Grosenbaugh, D.A. and Hood, D.M. (1999) The pathophysiology of chronic laminitis-pain and anatomic pathology.
- Vet. Clin. N. Am.: Equine Pract. 15, 395-417.
- O'Grady, S.E. (2002) Managing chronic laminitis using 'glue-on' shoeing technology.
- Equine vet. Educ. 14, 157-162.
- Page, B. (1999) How to mark the foot for radiography.
- Proc. Am. Ass. equine Practnrs. 45, 148.
- Parks, A.H. (2003) Chronic laminitis.
- In: Current therapy in equine medicine 5, Ed: N.E. Robinson, W.B. Saunders, St. Louis. pp 520-528.
- Pollitt, C.C. (1995) Laminitis.
- In: Color Atlas of the Horse's Foot, Mosby-Wolf, London. pp 169-205.
- Pollitt, C.C. (1999) Equine laminitis: a revised pathophysiology.
- Proc. Am. Ass. equine Practnrs. 45, 188-192.
- Redden, R.F. (1997) Shoeing the laminitic horse.
- Proc. Am. Ass. equine Practnrs. 43, 356-359.