Treatment of Angular and Flexural Limb Deformity (ALD/FLD)

AAEP FOCUS ON THE FIRST YEAR OF LIFE PROCEEDINGS / 2014
Treatment of Angular and Flexural Limb
Deformity (ALD/FLD)
Ashlee E. Watts, DVM, PhD, DACVS

Author’s address—Department of Large Animal Clinical Sciences,
College of Veterinary Medicine & Biomedical Sciences, Texas
A&M University, College Station, TX 77843-4461; e-mail:
[email protected].
When congenital flexural deformity is due to contracture of soft
tissue structures resulting in joint flexion, treatment is dictated
by severity.
T
If the foal can stand to nurse normally, restricted exercise may
be all that is needed. The goal of restricted exercise is to
exercise and stretch the soft tissues (tendon, ligament, joint
capsule) while protecting the limbs from overuse leading to
pain and worsening contracture. Restricted exercise may
consist of controlled exercise (handwalking the mare, allowing
the foal to follow) or short periods of turnout. Daily or twice
daily assessment of conformation is required to be sure that the
amount of exercise is appropriate (Fig. 2).
reatment of the various forms of angular and flexural limb
deformities differ depending on location and cause of the
deformity, age, severity, body type, risk factors, and time.
I. CONGENITAL FLEXURAL LIMB
When congenital flexural deformity is due to laxity of soft
tissue structures resulting in joint hyperextension, exercise
should be carefully controlled to encourage strengthening and
normal development of these structures without allowing
damage to hyperextended joints. Controlled exercise such as
handwalking the mare, allowing the foal to follow, is generally
preferred to turnout exercise for flexural laxity. Additional
measures such as palmar/plantar heel extensions can help to
temporarily improve the hyperextension, protecting the joints
and soft tissues while the foal becomes stronger and grows (Fig.
1). In very severe hyperextension due to soft tissue laxity, it
may be necessary to splint the limb in partial flexion during
controlled exercise to allow a gain in strength without damage
to hyperextended joints and soft tissues.
Fig. 2. There is mild contracture of the carpus and the foal is mildly
buckling in his knees. The fetlocks are similarly upright. Notice
the taut extensor tendons. The foal could nurse normally and
resolved with controlled exercise only.
If the foal can stand to nurse, but does so with the fetlock joint
maintained in flexion, the fetlock joint should be splinted to
encourage weighted stretching of the flexor tendons. This is
because with the fetlock knuckled forward, the flexor tendons
become lax and the extensor tendons become taut, only
exacerbating contracture of the flexor tendons. Analgesics and
oxytetracycline will also be useful (Fig. 3).
Fig 1. There is laxity of the flexor tendons causing hyperextenstion
of the distal limb and the toe is not touching the ground. A popsicle
stick heel extension has been taped to the foot to increase plantar
support while the foal gains in strength and grows.
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AAEP FOCUS ON THE FIRST YEAR OF LIFE PROCEEDINGS / 2014
be modified to a more extended, or fully extended position.
Once a normal joint angle is achieved, the foal is weaned from
splinting and controlled exercise is introduced. The duration of
this weaning period is dictated by the severity of the deformity,
growth rate of the foal and the conformation of the limb after
periods without the splint and after exercise (Fig. 4).
Fig. 4. Severe carpal contracture due to flexor tendon contracture
was treated with oxytetracycline, splints, NSAIDs and
confinement. One week later, the foal is no longer wearing splints
and is able to stand to nurse normally.
Fig. 3. There is severe fetlock contracture. This foal could stand
to nurse without assistance, but aggressive management was
indicated because the persistent fetlock flexion would only
exacerbate the deformity (photo courtesy Dr. Norm Ducharme,
Cornell University).
II. ACQUIRED FLEXURAL DEFORMITY
If the foal cannot stand to nurse or the foal can nurse, but
quickly becomes exhausted from effort, more aggressive
treatment is required. Aggressive management of severe
contractures includes administration of oxytetracycline (3
grams IV in IV fluids), confinement, splints and/or casts, heel
elevations, judicious analgesics and occasionally surgical
transection of soft tissue structures. Splints should achieve as
much extension of the limb as possible, stretching and
weighting the flexor tendons while allowing the foal to stand on
extended (or partially extended) joints with little work on the
foal’s part. As always, but especially in the young foal, splints
should be very well padded with a heavy bandage and
monitored carefully and changed frequently to avoid rub sores.
The angulation of the splint will depend on the deformity, and
may need to be modified several times during the course of
treatment. For example, a severe carpal contracture may need
to be splinted in partial flexion initially and later the splint will
When flexural deformity is acquired, treatment with splints,
analgesics and restricted exercise is similar to that for
congenital flexural deformity, with a higher proportion of cases
requiring surgical transection of soft tissues. Additionally, foot
trimming may also be useful. For the distal interphalangeal
joint, the check ligament of the DDFT is most commonly
transected and occasionally the DDFT itself is transected as a
last resort. Light use as an athlete can be attained after surgical
transection of the DDFT. For the metacarpo(tarso)phalangeal
joint, the check ligament of the SDFT with or without the check
ligament of the DDFT are transected. Similarly to the coffin
joint, the SDFT can be transected as a last resort with fetlock
deformities. For the carpus, the check ligament of the SDFT is
transected. In very severe cases of carpal contracture, the
ulnaris lateralis and the flexor carpi ulnaris may need to be
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AAEP FOCUS ON THE FIRST YEAR OF LIFE PROCEEDINGS / 2014
transected as well.1 It is important to remember that for the
fetlock joint, a heel elevation may result in marked
improvement of the deformity and severe trimming of the heels
may exacerbate the deformity in most cases.
A major difference between congenital and acquired flexural
deformities is the importance of nutrition in their management
– balanced nutrition with minimized energy intake and
restriction of calories should be achieved to slow the foals’
growth as much as possible. Recently, commercially available
complete feeds made specifically for the foala have been
developed and can be used for precise caloric control while
maintaining adequate vitamin and mineral balance.
Similar to congenital contractures, I do not use toe extensions
because of the potential to harm the dorsal laminae. However,
I will often use a built up and protected toe with either glue or
a toe shoe to allow continued rasping/lowering of the heels
while maintaining toe height when treating a club foot (Fig. 5).
Fig. 6. Radiographs of a dysmature foal with incomplete
mineralization of the bones in the knee (carpus) on the left
compared to normal ossification on the right. No limb deformity
is present. The foal was severely exercise restricted and allowed to
ossify as it matured. The foal eventually ossified and did not
develop crushing of the bones or subsequent limb deformities.
IV. CONGENITAL AND ACQUIRED ANGULAR LIMB
Therapies for angular limb deformities due to disparate
epiphyseal/metaphyseal growth are most often manipulation of
growth, either medically or surgically. The most rapid period
of growth, and thus the greatest chance of manipulating growth
to correct the deformity, occurs during the first 5 weeks of life
for the distal metacarpal(tarsal) physis and the first 5 months of
life for the distal radius and tibia. Complete physiologic closure
is much later, occurring around 10-12 weeks of age for the distal
metacarpal(tarsal) physis and around 20 months of age for the
distal radius and tibia.2,3 Medical or surgical therapies are
elected dependent of the severity of the deformity in
combination with the duration remaining of rapid growth for
that physis – i.e. a moderate fetlock varus at birth will likely be
treated medically, whereas a moderate fetlock varus at 4 weeks
of age will likely be treated surgically. Another thing to
consider when selecting therapies is the other joints in that limb.
A moderate to severe carpal valgus at 1 month of age, despite
having plenty of time to correct, may need to be treated more
aggressively because of the chance for inducing a secondary
fetlock varus deformity (Fig. 7).
Fig. 5. A toe shoe is placed after the check ligament of the DDFT
has been transected to allow continued rasping and lowering of the
heels.
III. CONGENITAL FLEXURAL OR ANGULAR LIMB
Crushing of incompletely ossified cuboidal bones can result in
angular and/or flexural deformity. Most often angular limb
deformity in the forelimb and flexural deformity of the
hindlimb. When congenital flexural or angular deformity is due
to crushing of incompletely ossified cuboidal bones, the
prognosis is guarded for normal development and function. If
there is incomplete ossification without crushing, exercise
should be severely restricted and casts and/or splints should be
used as needed to keep the limbs straight while the foal is given
time to mature and allow ossification to occur (Fig. 6). Because
incomplete ossification may not have a flexural or angular limb
deformity present until crushing has occurred, all dysmature or
immature foals should be checked radiographically for
appropriate ossification.
Farriery can be used to treat some angular limb deformities,
keeping in mind that moderate or severe deformities may need
surgical growth manipulation, which can only be utilized in
similar time frames as farriery. The hoof wall should be
trimmed on the side to which the limb deviates (if the limb toes
out, trim out). The hoof wall can also be extended distally and
abaxially on the opposite side to the trim with glue or a shoe,
concurrent with trimming. The extension will compress the
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AAEP FOCUS ON THE FIRST YEAR OF LIFE PROCEEDINGS / 2014
staples, screw & wire, and single screws.5,6 For the fetlock and
tarsus, most surgeons elect a transphyseal screw. For the
carpus, because overcorrection has occurred, many surgeons
elect a transphyseal bridge with screws and wire. It is critical
to stress to owners the importance of implant removal as soon
as the limb is straight as overcorrection could occur if the
implants were not removed.
REFERENCES AND FOOTNOTES
1.
2.
3.
4.
Fig. 7. A weanling foal with right forelimb carpal valgus that
resulted in right forelimb fetlock varus.
5.
growth plate on the ‘too long’ side, thereby slowing its growth
and hastening growth on the opposite, ‘too short’ side. For
example, a fetlock varus is trimmed medially and the extension
is applied laterally. One must be careful when using farriery to
correct major deformities. For example, trimming and
extensions to correct a severe carpal valgus (>10-15 degrees) in
a young foal may exacerbate or cause fetlock varus in the same
limb. Thus, with severe carpal valgus in the very young (<2-3
months of age) foal, it is important to monitor the fetlocks for
developing varus deformity and only continue medical
treatment if the carpal valgus is improving rapidly in the
absence of fetlock abnormalities.
6.
Charman RE. Vasey JR. Surgical treatment of carpal
flexural deformity in 72 horses. Aust Vet J
2008;86(5):195,9; quiz CE1.
Fretz PB, Cymbaluk NF, Pharr JW. Quantitative
analysis of long-bone growth in the horse. Am J Vet
Res 1984;45(8):1602-9.
Vulcano LC, Mamprim MJ, Muniz LM, et al.
Radiographic study of distal radial physeal closure in
Thoroughbred horses. Vet Radiol Ultrasound
1997;38(5):352-4.
Read EK, Read MR, Townsend HG, et al. Effect of
hemi-circumferential periosteal transection and
elevation in foals with experimentally induced
angular limb deformities. J Am Vet Med Assoc
2002;221(4):536-40.
Baker WT, Slone DE, Lynch TM, et al. Racing and
sales performance after unilateral or bilateral single
transphyseal screw insertion for varus angular limb
deformities of the carpus in 53 Thoroughbreds. Vet
Surg 2011;40(1):124-8.
Carlson ER, Bramlage LR, Stewart AA, et al.
Complications after two transphyseal bridging
techniques for treatment of angular limb deformities
of the distal radius in 568 Thoroughbred yearlings.
Equine Vet J 2012;44(4):416-9.
a. Purina Equine Junior, Purina Mills, St. Louis, MO
63166-6812.
To best utilize the periods of rapid long bone growth, surgical
manipulation of growth to correct angular limb deformity due
to disparate epiphyseal/metaphyseal growth should be
performed around 4 weeks of age for the fetlock and 4 months
of age for the carpus(tarsus). Manipulation can be performed
at older ages, bearing in mind that with increasing age there is
reduced growth potential and therefore reduced potential to
correct the deformity. Periosteal stripping involves elevation of
the periosteum adjacent to the physis on the side to which the
limb deviates (concave side), theoretically enhancing growth on
the side of the limb that it is performed. There is some
controversy regarding the efficacy of periosteal elevation and
clinical evidence of efficacy is lacking.4 Transphyseal bridging
involves placing a surgical implant(s) on the opposite side from
which the limb deviates (convex side) to temporarily stop
growth. Continued growth occurs opposite to the surgical
implant, thereby straightening the limb. There are various types
of implants and techniques used to achieve this growth arrest:
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