Feasibility And Availability of Standard-Sized Cup At The True Acetabulum In Acetabular Reconstruction of Crowe Type IV Hip Dysplasia
Abstract Background: This study aimed to investigate the morphological features and 2D/3D coverage parameters of the true acetabulum of Crowe type IV hips and to identify the optimal component center of standard-sized cup implantation.Methods: A total of 42 Crowe IV hips in 37 patients and 36 normal hips were included in the present study. Based on 3D reconstruction, anatomy and volume of the true acetabulum were measured quantitatively. Through simulated implantation, the feasibility of standard-sized cup implantation was evaluated by cup-based morphological assessments and coverage parameters. Eventually, bony landmarks for optimal component center location were determined. Mean follow-up was 4.7 years (1.2 to 6.3 years).Results: All the dysplastic hips were placed with standard-size acetabular implant (44.67mm, 44 to 48mm) successfully, with no acetabular implant loosening during the follow-up period. Compared with control group, the dysplastic acetabulum was more anteverted and abductive, with a thicker medial wall. According to the true acetabulum, bone stock is relatively sufficient in the posterior direction and prominently deficient in the anterosuperior and superior direction. Average 3D component coverage can reach 79.89% by standard-sized cup implantation at the true acetabulum. Regarding the component opening plane, the optimal component center located at the midpoint between the superolateral and posteroinferior point of the true acetabulum. Conclusion: Standard cup implantation is feasible and available in Crowe IV hip at the true acetabulum. The optimal component center was determined to be relatively constant based on the useful bony landmarks.Level of evidence: Therapeutic Level 3b.