Background: Operative strategies to overcome the anatomical
anomalies in patients with osteoarthritis secondary to developmental dysplasia
of the hip remain controversial. The objective of this study was to determine
the outcomes of total hip replacement with a grit-blasted cementless threaded
cup and a cementless straight stem in patients with developmental
Methods: Ninety-three patients with developmental hip dysplasia who
had been treated with a total of 121 cementless total hip arthroplasties were
clinically assessed at a mean of 9.3 years. The acetabular reconstruction was
done with a cementless threaded cup, which was medialized to ensure that at
least one thread was anchored in the bone in order to achieve good primary
stability. All radiographs were analyzed retrospectively.
Results: Kaplan-Meier survivorship analysis, with radiographic
evidence of aseptic loosening as the end point, predicted a survival rate of
97.5% for the acetabular component and 100% for the femoral stem at 9.3 years.
The average Harris hip score for the unrevised hips improved from 34.0 points
preoperatively to 84.1 points at the latest follow-up evaluation. The average
total volume of polyethylene wear at the time of final follow-up was 73.6
Conclusions: These wear and loosening rates demonstrate that very
good results were achieved in this relatively young patient population when
the hip joint center had been properly restored, even when a small cup with a
thin polyethylene liner had been used.
Level of Evidence: Therapeutic study, Level IV (case
series [no, or historical, control group]). See Instructions to Authors for a
complete description of levels of evidence.