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The hip joint can be approached from the front of the hip
(anterior approach), from the back (posterior approach), from the
side (trans-trochanteric approach), from midway between front and
side (antero-lateral approach), or through a two incision approach
(one anterior, and one posterior).
With the side-approach the trochanter bone is cut, and later
re-attached with steel wires. This was the standard for many years,
but is now only occasionally used for re-operations.
THE POSTERIOR APPROACH is the one used by most surgeons.
Small, unimportant tendons (short rotators) are detached to get to
the hip joint, and re-attached later in the operation. Normal
walking returns much sooner than with the antero-lateral approach,
sometimes in less than six weeks.
The mini-incision hip replacement is an important recent
development. It is used with the posterior approach. In the past the
skin incision was ten or more inches long. With special new
instruments, this approach is now possible through an incision as
small as three inches in thin patients. In obese patients, the
incision is less than half what it would otherwise have been.
A smaller incision means less blood-loss. There is also less
trauma to the muscles and ligaments around the hip, so much less
pain, and an even quicker return to normal walking. Few orthopedic
surgeons have learned the posterior mini-incision. Fewer still can
do a perfect hip replacement, with accurate leg length, through such
a small incision.
THE ANTERO-LATERAL APPROACH, is the second most commonly
used. The chance of hip dislocation is thought to be less with this
approach. However, there is a trade-off. About one third of the most
important hip muscle (gluteus medius) is detached from the bone, and
later re-attached. This weakens it, leaving most patients with a
limp, sometimes for up to a year.
IN THE ANTERIOR APPROACH the whole operation is done
through a single incision in the groin. The muscles are not cut, but
are spread apart. The ligaments that hold the hip together still
have to be cut. The procedure is done under x-rays. The operation is
risky, even in the best hands. It is very difficult to line up the
femur bone through this incision, and see it clearly. There is much
room for error in the placement and sizing of the femoral component,
as well as in getting the leg length right.
THE TWO-INCISION APPROACH is a very recent development.
Two 3-inch incisions are made: one in the groin, as in the anterior
approach, and one over the back of the hip. Muscles are not cut, but
are spread apart, and are disturbed less than with any other
approach. Normal walking returns sooner with this approach than
with any other, sometimes in as little as two weeks. The
operation is difficult, and very few surgeons have been trained to
do it.
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