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).
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 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