Long-term results of total hip arthroplasty with a cemented custom-designed swan-neck femoral component for congenital dislocation or severe dysplasia - A follow-up note

Background: This follow-up study updates the results in a consecutive series of nineteen cemented total hip replacements with a swan-neck femoral component in patients with congenital dislocation or severe hip dysplasia. The series was previously reported on in 1993. Methods: The patients were petite, with an average height of 152 cm and an average weight of 50 kg, and the femoral canals could not accommodate an off-the-shelf femoral component. Sixteen of the nineteen hips were available for follow-up at an average of 13.3 years (range, eleven to twenty years). Fourteen hips had up-to-date clinical and radiographic examinations. Results: At the time of the latest follow-up, thirteen hips were rated as excellent; two, as good; and one, as a failure because of loosening of both components requiring revision eleven years after the index operation. Another hip required acetabular revision because of loosening fifteen years after the index operation. The rates of femoral and acetabular component revision were 6% and 12.5%, respectively. Radiographic analysis demonstrated that no femoral component was loose. One cup was definitely loose at 19.5 years, and three cups were possibly loose at an average of fourteen years. The radiographic rate of acetabular loosening was 33%. The total rate of cup failure (radiographic loosening and revision) was 43%. Conclusions: The excellent clinical and radiographic results associated with the swan-neck femoral component, and the 94% rate of survival, at an average of 13.3 years (range, eleven to twenty years) indicate that the biomechanical objectives of this custom-designed prosthesis for patients with congenital dislocation or severe hip dysplasia were met. On the basis of this favorable long-term experience, we still use this prosthesis when the anatomic abnormality cannot be adequately addressed by use of a commercially available prosthetic component.