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Periacetabular Osteotomy is a hip preserving procedure
performed to correct a congenital deficiency of the acetabulum:
acetabular dysplasia. Periacetabular Osteotomy (PAO) for acetabular
dysplasia preserves and enhances the patient's own hip joint rather than
replacing it with an artificial part or THR. The goal is to alleviate
the patient's pain, restore function, and maximize the functional life
of their dysplastic hip.
The results after PAO, which preserves the patient's own
hip, justify its use and the long term results can be better than what
the patient could have obtained from a hip replacement. The patient's
own hip is a living tissue with self-maintenance capabilities, whereas
deterioration with time is inevitable for an artificial part. The
sensory capabilities of the joint are preserved and the patient can
continue to remain as active as symptoms or their lack of permits. The
patient with a total hip replacement, however, always must be cautioned
regarding possible hip dislocation and be restricted from vigorous
activity
PAO is a procedure that was developed and first performed in 1984 in
Bern, Switzerland by Professor Reinhold Ganz with the assistance of
Jeffrey Mast, M.D. (an American surgeon from Sparks, Nevada who was
spending a year's sabbatical leave with Prof. Ganz).
Operative Procedure
Periacetabular osteotomy involves performing several
bone cuts (osteotomies) around the acetabulum and redirecting it in an
optimal position so that the femoral head is adequately covered. The
osteotomy is then stabilised with about three screws (see figure 2). The
procedure is a major operation with significant blood loss and many
patients chose to donate their own blood prior to surgery. A Cell Saver
is used during the operation to reinfuse blood lost during the
operation. The procedure normally takes about 2.5 hours to perform. An
image intensifier is used throughout the procedure. This allows for
continual x-ray checking of the correction during the operation.
Acetabular Dysplasia
Acetabular dysplasia is a condition defined by
inadequate development of an individual's acetabulum. The resulting
acetabulum is shallow and "dish shaped" rather than "cup shaped". The
upper portion of the acetabulum is obliquely inclined outward rather
than having the normal horizontal orientation. Due to the abnormalities,
the superior and usually anterior femoral head are incompletely covered
by this dysplastic acetabulum.
Individuals with acetabular dysplasia usually develop through childhood
and adolescence without symptoms of their problem. The patient often
starts to experience pain from their hip at about 30 years old.
Their doctors perform x-rays and the abnormality (acetabular
dysplasia) is found. Sometimes, patients might be treated for hip
problems as an infant or child.
Acetabular dysplasia is often also associated with abnormalities in the
shape of the upper femur which may also cause pain. Acetabular dysplasia
is associated with an abnormally high stress on the outer edge or tim of
the acetabulum which leads to degeneration of the articular cartilage
(arthritis). It is also possible for the rim cartilage of the acetabulum
to break down or have a fatigue fracture due to the overload.
When the diagnosis of acetabular dysplasia is made, the x-ray also
usually shows a sign of arthritis which is most commonly an acetabular
cyst though increased bone density, a femoral head cyst, osteophytes
(bone spurs), and possibly cartilage thinning. If the dysplasia is left
uncorrected the arthritis continues to progress until it becomes severe.
This progression may take a few years or in some cases only a few
months. The hip becomes more and more painful while normal hip motion is
lost.
Additional Resources about PAO
Bernese periacetabular osteotomy for hip dysplasia in young adults
Periacetabular Osteotomy for the Treatment of Acetabular Dysplasia
Associated with Major Aspherical Femoral Head Deformities
Periacetabular Osteotomy in the Treatment of Neurogenic Acetabular
Dysplasis
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