The severity of developmental dysplasia of the hip does not correlate with the abnormality in pelvic incidence

Rongshan Cheng,Zhenan Zhu,Huiwu Li,Tsung-Yuan Tsai,Muyin Huang,Willem Alexander Kernkamp,Liao Wang

doi:10.1186/s12891-020-03632-4

Abstract

BackgroundThe purpose of this study was to investigate the association between the severity of Developmental dysplasia of the hip (DDH) and the abnormality in pelvic incidence (PI).MethodsThis was a retrospective study analyzing 53 DDH patients and 53 non-DDH age-matched controls. Computed tomography images were used to construct three-dimensional pelvic model. The Crowe classification was used to classify the severity of DDH. The midpoint of the femoral head centers and sacral endplates were projected to the sagittal plane of the pelvis. The PI was defined as the angle between a line perpendicular to the sacral plate at its midpoint and a line connecting this point to the axis of the femoral heads. Independent sample t-tests were used to compare the differences between the PI of DDH group and the non-DDH controls group. Kendall’s coefficient of concordance was used to determine the correlation between the severity of DDH and PI.ResultsPatients with DDH had a significantly (p = 0.041) higher PI than the non-DDH controls (DDH 47.6 ± 8.2°, normal 44.2 ± 8.8°). Crowe type I patients had a significantly (p = 0.038) higher PI (48.2 ± 7.6°) than the non-DDH controls. No significant difference between the PI in Crowe type II or III patients and the PI in non-DDH controls were found (Crowe type II, 50.2 ± 9.6°, p = 0.073; Crowe type III, 43.8 ± 7.2°, p = 0.930). No correlation was found between the severity of DDH and the PI (r = 0.091, p = 0.222).ConclusionsNo correlation was found between the severity of DDH and the PI. The study confirmed that the PI in DDH (Crowe type I) group was higher than that of the non-DDH control group, while the PI does not correlate with the severity of DDH.

Highlights

The purpose of this study was to investigate the association between the severity of Developmental dysplasia of the hip (DDH) and the abnormality in pelvic incidence (PI)
There were no significant differences between the PI in Crowe
Our results showed that the PI in Crowe type I-III DDH patients was 3.43° higher than that of the non-DDH control group, which is in agreement with the results in the literature

Summary

Introduction

The purpose of this study was to investigate the association between the severity of Developmental dysplasia of the hip (DDH) and the abnormality in pelvic incidence (PI). Developmental dysplasia of the hip (DDH) is characterized by a shallow, obliquely oriented acetabulum and is a known cause for secondary osteoarthritis (OA) of the hip [1]. Due to the compelex deformity around hip, total hip arthroplasty (THA) in patients with OA secondary to DDH is reported with a higher rate of postoperative dislocations [3]. The increased dislocation rates to DDH are most consistent with increased risk for post-operative THA dislocation patients that have a decreased pelvic incidence (PI) [2, 5, 6]. In DDH patients the increased or decreased PI may cause the in higher rates of OA, LBP, and dislocations after THA. Few studies have investigated this subject [2, 5, 6]

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