Using radiography and computer tomography (CT) we studied the morphology of 83 hips in 69 Caucasian adults with osteoarthritis secondary to developmental dysplasia of the hip (DDH). A previously published series of 310 hips with primary osteoarthritis was used as a control group. According to the Crowe classification, 33 of the dysplastic hips were graded as class I, 27 as class II and 23 as class III or class IV.

The intramedullary femoral canal had reduced mediolateral and anteroposterior dimensions in all groups compared with the control group. Only in Crowe class II hips was the femoral neck-shaft angle increased. The proximal femur had more anteversion in all the developmental dysplasia of the hip groups, ranging from 2° to 80°. Templated measurement of acetabular dimensions for plain radiography closely matched measurements taken by CT.

The results of our study confirm the observations previously confined to the Japanese population.

Purpose: Hip prosthesis for sequelar developmental dysplasia of the hip is a therapeutic challenge because of the anatomic deformity and the young age of the patients. The purpose of this work was to report results obtained using a non-cemented femoral stem with an intramedullar design and a prosthetic neck custom-made to match individual anatomy observed on preoperative computerised tomographic.

Material and methods: This study included 257 hips with a mean follow-up of 5.6 years. Mean age at implantation was 55 years (range 17–78). The computed tomography study assessed: dislocation according to Crowe, leg length discrepancy, and acetabular anteversion and diameter. The cup was not cemented and was inserted with an anchor hook in the obturator foramen for implantation in the paleoacetabulum. The medullary canal was prepared using a blunt reamer shaped like the definitive prosthesis. The prosthetic neck was designed individually to match the lever arm and anteverion.

Results: There were 174 cases of dysplasia and 83 dislocations (39% grade 1, 30% grade 2, 14% grade 3 and 17% grade 4). Mean lengthening was 39 mm. The mean ante-verion was 28±16° and the mean anteroposterior diameter of the acetabulum was 51 mm. The Harris clinical score improved from 58 points preoperatively to 93 points at last follow-up. The follow-up x-rays showed osteointegration in 88% of the cases with osteolysis in 5% and one stem impaction. The prosthesis had to be changed for six hips: two for infection, one for dislocation and two for nonfixation. The 11-year survival rate was 97%.

Discussion and conclusion: This study illustrates the anatomic sequelae observed in patients with developmental dysplasia of the hip and demonstrates a surgical solution for these problems. There is no correlation between dislocation and the degree of anteversion so it is difficult to assess the difficulty of inserting a non-cemented stem without preoperative computed tomography. The good 11-year survival is encouraging for this young and active population.

Purpose: Implantation of a prosthesis on a remodelled femur can cause technical difficulties affecting the outcome of the arthroplasty. We performed a tridimensional study of the femoral anatomy before prosthesis implantation for sequelar congenital hip dislocation.

Material and method: The series included 312 hips in 262 patients. The same radiography and computed tomography work-up was perfomred in all patients. There were 288 women and 84 men, men age 56 years. Mean weight was 66 kg and mean height was 163 cm. The crowe classification was 195 dysplasia, 123 dislocations (41% class I, 27% class II, 13% class III, 19% class IV). Telemetric measurements were: femoral isthma, the centre of the lesser trochanter, limb length discrepancy, the cephalo-cervico-diaphyseal angle. Computed tomographic measurements were: anterio-posterior and mediolateral dimensions and femur funneling, helitorsion between the bichondylar plane and the upper femur, anteroposterior diameter of the acetabulum.

Results: The mean mediolateral and anteroposterior diameters of the femoral canal at the isthma were 9.8 and 13.1 cm respectively in dysplasia and 9.3 and 12.6 cm, 9.4 and 12.7, and 9.7 and 13.6 cm in I, II, and III–IV congenital dislocations respectively. The femoral funneling index varied from 1.9 to 7.6 in dysplasia and from 2.6 to 7.9, 2.1 to 8.4 and 2.1 to 8.7 in I, II, and III–IV congenital dislocations respectively. The mean cephalo-cervico-diaphyseal angle was 129.3°, 131.9°, 136.8°, and 127.4° respectively. Maximal leg length discrepancy was 45, 57, 71, and 82 cm respectively. Mean helitorsion was 22.9° (1°–52°), 36.4° (8°–86°), 43.2° (2°–82°- and 38.4° (6°–68°) respectively. The mean anteroposterior diameter of the acetabulum was 52, 51.2, 53.1; and 49.6 cm respectively.

Discussion and conclusion: The dysplastic or dislocated femur is narrower than the normal femur with wide variations in funneling and cephalo-cervico-diphyseal angle. The mean difference in leg length increases gradually with helitorsion but with wide individual variability, irrespective of the grade. These tridimensional anatomic data can be useful for predicting difficulties in prosthetic treatment of these patients.