Effect of acetabular tilt angle on acetabular version in adults with developmental dysplasia of the hip

Abstract

To investigate the difference in acetabular tilt angle (ATA) between adults with deve-lopmental dysplasia of the hip (DDH) and normal adults and the effect of ATA on acetabular version. Between February 2009 and October 2015, 31 adult female patients with DDH (39 hips) (DDH group) and 31 female patients with osteoarthritis of the knee (31 hips) who had no history of hip disease (control group) were included in this study. The average age was 39 years (range, 18-59 years) in the DDH group, and was 69 years (range, 52-79 years) in control group. The morphometric parameters of the acetabulum including ATA, acetabular anteversion angle (AAA), acetabular inclination angle (AIA), acetabular cranial anteversion angle (ACAA), and acetabular sector angle (ASA) were mea- sured by CT reconstruction; The ASA was used as an index for acetabular coverage of the femoral head. The correlation between ATA and other parameters was analyzed using Pearson correlation analysis. The values of ATA, AAA, and AIA of the DDH group were significantly larger than those of the control group ( P<0.05). The ASA in all directions was significantly decreased in the DDH group when compared with the values in the control group ( P<0.05). There was no significant difference in ACAA between two groups ( t=1.918, P=0.523). The ATA was positively correlated with AAA and ACAA in the DDH group ( r=0.439, P=0.001; r=0.436, P=0.002), but there was no correlation between ATA and AIA ( r=0.123, P=0.308). In the control group, the ATA was not correlated with AAA, ACAA, and AIA ( r=-0.004, P=0.724; r=-0.079, P=0.626; r=-0.058, P=0.724). Regarding acetabular coverage of the femoral head, the ATA and AAA were correlated negatively with anterior ASA ( P<0.05) and positively with posterior ASA ( P<0.05), but had no correlation with superior ASA ( P>0.05) in the DDH group; AIA was correlated negatively with anterior ASA and superior ASA ( P<0.05) and had no correlation with posterior ASA ( r=-0.092, P=0.440). In the control group, there was no correlation between ATA and ASA in any direction ( P>0.05). In the DDH group, defects of the acetabular anterior wall, lateral wall, and posterior wall were observed in 18 hips (46.2%), 15 hips (38.5%), and 6 hips (15.3%), respectively. ATA value of the posterior wall defect [(15.70±10.00)°] was significantly smaller than those of the acetabular anterior wall and lateral wall defects [(22.91±5.06)° and (21.59±3.81) °] ( P<0.05), but no signficant difference was found between anterior wall and lateral wall defects ( P>0.05). ATA will influence acetabular version in DDH. The anterior rotation of the acetabular fragment during periacetabular osteotomies is an anatomically reasonable maneuver for hips with anterolateral acetabular defect, while the maneuver should be avoided in hips with posterior acetabular defect.