Introduction to biomechanics


Do Lateral Wedge Insoles Relieve Pain Due To Osteoarthritis Of The Knee?

Osteoarthritis (OA) is the most common formthe ankle, resulting in slight correction of
of arthritis and affects approximately 30the varus knee deformity. Measures that many
million Americans. The underlying pathologystudies have included are subjective daytime
is altered biochemical changes in cartilage-pain, night time pain, length of time
the gristle that caps the ends of long bones.required to walk 50 feet, and reduction in
Cartilage consists of cells calledneed for non steroidal anti-inflammatory
chondrocytes that produce a matrix. Thedrugs. Different types of wedges are
chondrocytes sit inside this matrix, muchavailable. Some wedges are simply inserted
like grapes inside gelatin. With theinside a shoe. Other wedges come with a strap
development of OA, the chondrocytes no longerthat provides stability of the wedge inside
function properly. In addition, inflammatorythe shoe. According to one of the authors
changes occur within the joint. The endresponsible for the development of a popular
result is progressive and gradual loss ofwedged insole device, "The prevalence of knee
cartilage- leading to altered mechanics. PainOA in our society is increasing due to the
develops as a result of a number of factorsescalating proportion of elderly persons. A
including inflammation of the lining of theconservative therapy such as the use of an
joint, stimulation of pain receptors in theinsole that provides a low-cost complement or
joint capsule, and stretching of ligamentsalternative to surgical treatment would be a
and tendons due to the altered biomechanics.very useful adjunct to the care of patients
While, OA tends to affect weight-bearingwith knee OA and would benefit the health
joints such as the neck, low back, hips, andeconomy." [Toda Y and Tsukimura N. Randomised
knees, the area that seems to be responsibletrial to compare the clinical effects of an
for most visits to a rheumatologist's officeinsole with subtalar strapping and knee
is OA of the knee. Conservative OA of thesupport with hinged struts for patients with
knee treatment consists of a comprehensivevarus deformity osteoarthritis of the knee.
program incorporating patient education,Arthritis Rheum 2004; 50 (9) (supplement).
weight loss, exercise,Toda Y and Tsukimura N. A six-month follow-up
non-steroidal-anti-inflammatory drugs,of a randomised trial to compare the efficacy
glucocorticoid (cortisone injections), andof a lateral wedge insole with subtalar
viscosupplementation (injections of lubricantstrapping and an in-shoe lateral wedged
material). In a previous article, I discussedinsole in patients with varus deformity
the use of bracing for OA of the knee, whichosteoarthritis of the knee. Arthritis Rheum
is another conservative measure. In this2004; 50 (9) (supplement)]. While some
article I discuss a little-known but verydetractors point to flaws in study design,
effective means of reducing knee pain calledabundant anecdotal evidence as well as the
the lateral wedge insole. Lateral wedgedmultiplicity of studies pointing towards
insoles are aimed at patients with varuseffectiveness, suggest that these insoles
deformity knee OA. A varus deformity meansshould  at  least  be  given  a  try.
the patient has "bow-legs". Patients with
varus knee deformities due to OA haveNathan Wei, MD FACP FACR is a rheumatologist
significant pain involving the medialand Director of the Arthritis and
(inside) part of the knee. A number ofOsteoporosis Center of Maryland. He is a
studies have demonstrated that the use of theClinical Assistant Professor of Medicine at
lateral wedge insole, by lifting the outsidethe University of Maryland School of
of the foot, leads to valgus angulation ofMedicine.



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