Distant outcomes of the Chiari osteotomy 30 years follow up evaluation.

Background. The aim of my paper was to assess distant treatment results of patients who were treated because of hip displasia and the Chiari osteotomy was performed on those patients. Material and methods. I evaluated treatment outcomes of 27 patients who were treated at Poznan University of Medical Sciences, Clinic of Orthopedics, in 1965-1990. The Chiari osteotomy was performed on all patients for hip decenteration or hip subluxation after developmental displasia. 34 hips were evaluated (20 female and 7 male). The average age of patients was 13 years in the moment of the operation. The follow up examination was conducted 10-36 years after the Chiari osteotomy Results. After many years (30 years after the operation on the average), 37% of patients could fit into groups of very good and good results. I could assess the hips before the operation using only parameters marked on anteroposterior films. The radiographs of the hips showed displasia characterized by shallowness and steepness of the acetabulum, an increased apparent neck-corpus angle, low submersion of the femoral head in the acetabulum, and insufficient coverage of the femoral head by the acetabulum. On the radiographs taken one year after the operation I observed very good coverage of the femoral head proved by higher values (above quota) of the Wiberg angle, the Sharp angle, the Heyman and Herndon acetabulum-head indicator. I defined also a course of the osteotomy drafting an osteotomy angle, setting a degree of bone fragments displacement (medialisation), and a height of the osteotomy. Conclusions. 1. The Chiari osteotomy as a hip saving operation allows patients to function in satisfactory clinical conditions for many years. 2. When conducted correctly, the Chiari osteotomy considerably improves femoral head coverage not only in the frontal plane but also in the transverse plane. 3. Too wide osteotomy angle, more than 20 degrees , further than 50% displacement of a distal bone fragment and too low course of the osteotomy in relation to the apex of the femoral head extorted many a time by intraoperative situation, may favor worse patients clinical conditions some time later, considering acceleration of degenerative lesions confirmed before the operation.