LAS VEGAS — A free motion knee-ankle
orthosis may be used successfully in children with
Blount’s disease, according to research presented here.
Joseph Whiteside, CO, LO, Anatomical Concepts’ vice president and
clinical director of research and development, discussed successful outcomes in
treating
Blount’s disease using a knee-ankle orthosis (KAFO) at
the 2011 American Orthotic & Prosthetic Association’s National
Assembly.
The traditional protocol for treating Blount’s or other
bowing deformities involves a lock-knee orthosis. The
Varum-Valgum Adjustable Stress (V-VAS) Custom Offloading Knee Orthosis provides
another way to treat these deformities, especially in nontraditional and
overweight patients, using a free-motion design.
Unique designs
“What’s unique about the design is that you can independently
change the angle of the tibia or the femur and match that to the patient’s
need as far as offering a corrective force,” Whiteside said.
The orthosis does not need to be removed to adjust off-loading and the
mechanical axis is auto-aligning.
“It’s very easy to use — simply loosen a couple of the
screws. If you lengthen the medial upright distally, the tibial section will
move laterally, creating a valgus moment at the knee. The same thing can be
done with the femoral section. Loosen the two screws, lengthen the medial
upright. This adjustment results in a bending moment or corrective force
matched to the individual patient’s needs,” he said.
Whiteside discussed the parameters needed to determine whether a patient
has a Blount’s deformity and should be considered for the V-VAS device.
Blount’s deformities are characterized by a tibiofemoral angle (TFA)
greater than 15· and a metaphyseal-diaphyseal angle (MDA) greater than
11·. He said there should be evidence that the deformity is progressing
negatively. Whiteside also suggested considering the patient’s etiology
and pathophysiology, obesity and lateral thrust. The critical window for
treating Blount’s deformities is when the patient is between the ages of 2
and 3 years. Research suggests that the patient should be placed in an orthotic
device for a minimum of 1 year to ensure maximum effect, he said.
A nontraditional patient
Whiteside described a case study in which the V-VAS system was
successfully used on a nontraditional patient. The 2-year-old patient, who was
considered obese, had been using a lock-knee device for 6 months, but the TFA
and MDA of the deformity were still extreme. After nearly 17 months of treating
the patient unsuccessfully, the doctor fitted the patient, then 3 years and 10
months, with a V-VAS orthosis. Within 6 months, the TFA and MDA had both
decreased significantly, and follow-ups at 4 years and 5 years of age showed
great improvement.
Whiteside cited the significance of this success because the patient was
a nontraditional Blount’s patient. Typically, obese patients are not
treated orthotically. Also, patients who have not been diagnosed or orthotic
intervention received by 3 years of age are usually treated surgically, and
literature review shows a 60% to 70% failure rate of orthotic intervention with
bilateral involvement.
He said that orthotists and physicians attribute the success of the
V-VAS device to compliance and the free motion-joint system.
“With all of the systems out there, you have an elastic or Velcro
strap that is somewhat subjective because it is dependent on the caregiver to
tighten the strap appropriately. With this system, once you set that corrective
force into the system and place it onto the patient, it is reproducible every
time. It’s not dependent on the actual strap,” Whiteside said.
Whiteside hopes that this non-invasive solution will reduce the number
of surgeries made necessary by non-resolving Blount’s deformities. On
average, these patients undergo 2.5 surgeries per limb, per patient. The V-VAS
device aims to decrease that number and offset the financial burden caused by
multiple surgeries.
“The real factor you need to consider is that we have a device that
is non-invasive that can produce a great result due to the increased
compliance. It’s a great tool for us in orthotics and prosthetics.
It’s on our shoulders to inform patients and physicians about this device
and how we can make a difference,” he said.
First of all I want to praise the design of the Free Motion KAFO that
Joseph Whiteside CO, LO, has introduced to the profession. The adjustability
for growth and correction forces for genu varum is innovative for pediatrics as
well as the unique joint design, both of which have significant value. This
design concept can also be applied for skeletal dysplasia or rickets that can
present with genu varum/valgum.
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Janet G.
Marshall |
However, I have concerns over the validity of the claims for the
treatment of Blount’s as written in his article. The most obvious is
conclusions of success based on two studies. Furthermore infantile tibia vara
(aka Blount’s) is confined to the medial tibial plateau and medial
metaphysis that produces genu varum. This is measured by the MD angle
(metaphyseal/diaphyseal) for comparative studies and progression, which is not
mentioned in the article. Mechanical axis showing the varum in the radiographs
displays obvious improvement, but where is this coming from? Is this truly an
improved MD angle? Is there femoral bowing and joint laxity that contributes to
the varum? More scientific data and a greater number of cases are necessary to
draw conclusions that are being claimed.
— Janet G. Marshall, CPO,
LPO
Shriner’s Hospitals for Children, President, Association of
Children’s Prosthetic-Orthotic Clinics