Abstract
Acetabular dysplasia is the most common cause of secondary osteoarthritis of the hip joint resulting in many young adults requiring total hip replacement (THR). Although THR has a predictably good functional result, the longevity of prosthetic replacement in this young cohort of patients has been notably inconsistent. Therefore, there has been an increasing interest in better methods for treating acetabular dysplasia in young adults with the emphasis shifting from the femoral to the acetabular side during the last 10 years.
For reorientation of the acetabular fragment to improve coverage, various pelvic and periacetabular osteotomies have been proposed. Most necessitate more than one incision and change of patient position. The Bernese periacetabular osteotomy (PAO) combines complete and incomplete osteotomies, as well as a controlled fracture requiring only one approach. This is beneficial for the vascular supply of the acetabular fragment and allows an additional anterior capsulotomy without restrictions.
The osteotomies of the PAO are close to the joint and therefore allow a pronounced acetabular reorientation similar to juxta-articular triple osteotomies. Moreover, anteversion and medialization/lateralization of the center of rotation can be corrected with only minimal changes of the pelvic geometry. This enables a normal delivery in young females. The partially remaining posterior column protects the sciatic nerve from iatrogenic damage. The polygonal shape of the osteotomy and avoidance of soft tissue stripping (abductors) are advantageous for the stabilization of the reoriented fragment, thus facilitating early mobilization and rehabilitation.
Seventy-five dysplastic hips with a minimal follow-up of 10 years after PAO were evaluated. There were good to excellent result in 73% of these patients. The mean lateral center edge angle increased from 6° to 34° and the mean anterior center edge angle improved from 4° to 28°. The post-osteotomy index angle was successfully reduced from an average of 26° to 6°. Lateralisation of the femoral head was reduced from an average 16° to 10° compared to 11° on the contralateral side. Femoral head cranialisation also normalized from 9° to 4° compared to 5° on the opposite hip. Poor results were correlated with older patients, pre-existing arthritis, labral pathology, and mal-correction. Treatment of labral lesions was performed only as a supplementary measure if the labrum was unstable and included either refixation or resection.
The PAO is a technically demanding procedure, and is unforgiving of seemingly minor imprecision. With the fact that 85% of our major complications occurred within the first fifty osteotomies, it is obvious that a learning curve exists for this procedure. It is imperative that surgeons undertaking this procedure do so with a full understanding of each stage and have the necessary patience, attention to detail and adequate cadaveric experience with the technique.
The abstracts were prepared by David P. Davlin. Correspondence should be addressed to him at the Orthopedic Clinic Bulovka, Budínova 2, 18081 Prague 8, Czech Republic.
