Three-dimensional morphology of lunate surface in hip dysplasia: Theoretical implications for periacetabular osteotomy

Background

The objective of this study was to evaluate three-dimensional morphology of acetabular lunate surface in patients with dysplastic hip using three-dimensional computed tomography (CT), and to compare the lunate surface morphology between the normal and dysplastic hips.

Methods

Sixty seven dysplastic hips in symptomatic patients and 61 normal hips in healthy volunteers who underwent three-dimensional CT scanning were included in this study. The size and shape of the lunate surface was measured with a fully automated imaging technique using Mimics16.0 software; lunate surface morphology was compared between the normal and dysplastic hips on the radial spherical coordinate system.

Results

A general trend of inferomedial rotation of the lunate surface was observed in dysplastic hips. Dysplastic hips showed a remarkable decrease in total absolute and relative size of the lunate surface as compared to that in normal hips. The dysplastic hips were divided into four groups: superior area decrease group (SD); anterosuperior area decrease group (ASD); global area decrease group (GD); global area increase group (GI). The arc of the global increase (GI) subgroup (26.86%) was increased, while that of the remaining three subgroups was decreased as compared to that in the normal acetabulum group.

Conclusion

Three-dimensional information and fundamental morphological features of the lunate surface in dysplastic hips were significantly different from those in the normal group. These findings may aid precise computational biomechanical analysis, preoperative planning for periacetabular osteotomy (PAO), achievement of satisfactory cartilaginous congruency, and judgment of postoperative prognosis in addition to postoperative treatment evaluation.