It is estimated that
approximately 250,000 to 300,000
primary total hip replacements are
performed in the United States each
year. Hip replacements can be fixed
to the bone using special epoxy
cement called polymethylmethacrylate
or, using another technique called
cementless total hip replacements.
The majority of the hip replacements
currently use cementless fixation or
what is called biologic fixation,
which allows the bone to grow into
or onto the surface of the
prosthetic components. This
phenomenon is known as biologic
fixation. Implants are press fitted
into the femur and acetabulum socket
in a stable fashion, allowing
immediate implant stability at the
time of surgery and then, subsequent
development bone ingrowth will
occur. The lining of the joints
usually has a plastic socket (high
density plastic or Teflon) that
moves with a cobalt chrome head.
This is the new bearing or surface,
which allows painless range of
motion and movement.
The modern era of total joint
arthroplasty began in 1960 with the
development of the total hip
replacement consisting of a stemmed
stainless steel replacement of the
femoral head articulating with the
high density of plastic implant.
Both components are fixated with
special polymethylmethacrylate
cement. The goal of total joint
replacements is simple, that is, to
relieve pain, provide motion with
stability and correct any deformity.
Total hip replacement is indicated
in individuals with painful or
disabling arthritic joints that are
no longer responsive to non-surgical
treatment. We can correct painful
hips, limb length inequality, and
limited motion with the current
state of the art hip replacements.
In the early 20th century
biologic and inorganic materials for
hip replacement became popular.
Initially there were certain body
tissues used to eliminate painful
hips. Gold foil was tried in 1912,
molded hip replacements were tried
in 1923 and glass material was also
tried. Next, more durable material
such as pirax or bakelite, were
tried, but had severe foreign body
reactions. Then, vitallium was used
followed by metal on metal.
Unfortunately due to patient, or
wife complaints of squeaking, this
lead to the advancement of acrylic
cement for fixation of high density
plastic sockets and the metal
components glued to the bone. This
was very successful in the early
70's. It started initially in
England and Europe and was
introduced to the United States in
the early 70's. With the advancement
in technology we have improved the
implant fixation, achieving biologic
fixation as well as better wear
characteristics regarding the
articulating surfaces. Presently, we
have high density polyethylene which
improves the results by decreasing
the wear. We currently have 95
percent good and excellent results
performing hip replacements. We also
can correct deformity, restore range
of motion, add stability, and
restore limb length inequality
problems. There are potential
complications associated with this
surgery but the benefits easily
outweigh the risks..