Tonnis triple pelvic osteotomy for the management of late residual acetabular dysplasia: mid-term to long-term follow-up study of 54 patients

The authors reviewed 54 (58 hips) patients with acetabular dysplasia following developmental dislocation of the hip (DDH), treated by triple pelvic osteotomy according to the Tonnis technique. The aim of our study was to report the long-term clinical and radiographic results of the operation at a mean follow-up of 12 years (from 7 to 20). At diagnosis, all the hips were painful, the Wiberg angle measured less than 20 degrees, and no radiographic signs of osteoarthritis were present. At follow-up, 82.7% of the operated hips showed either excellent or good results, according to Harris, and the Wiberg angle measured an average of 34 degrees (from 26 degrees to 45 degrees). We encountered five complications: one acetabular malrotation and four asymptomatic ischial nonunions. In conclusion, we believe that, although Bernese periacetabular osteotomy is nowadays considered the gold standard for the surgical treatment of the dysplastic hip following DDH, Tonnis osteotomy represents a good treatment option: it is technically easy, enables direct visualization of the three osteotomies, leads to few complications, and its learning curve is short. The absence of radiographic signs of osteoarthritis and hip congruency before surgery are the basic requirements to achieve a successful result.