Bone mineral densities in patients with developmental dysplasia of the hip

Are there associations between hip geometry and bone quality? An analysis on 3074 adults from a general population

INTRODUCTION

Patients with reduced bone mineral density and altered hip geometry are susceptible for hip pathologies. Knowledge on associations between bone properties and hip geometric parameters might facilitate identification of patients at risk for hip pathologies. The aim of the present study was to identify associations of bone properties assessed by quantitative ultrasound (QUS) at the heel and hip geometric parameters like center-edge angle (CE), neck-shaft angle (NSA) and alpha angle.

MATERIALS AND METHODS

Hip geometric parameters (CE, NSA and alpha angle) of 3074 participants from the population-based Study of Health in Pomerania were assessed on magnetic resonance imaging. QUS was performed on both calcanei providing broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness-index. Based on the stiffness-index the individual osteoporotic fracture risk (low, moderate or high) was determined. Associations between QUS-based and hip geometric parameters were calculated in linear regression models adjusted for age, sex, body height and weight. Interactions of QUS markers with age and sex on hip geometric parameters were tested.

RESULTS

Significant inverse associations between BUA (β = - 0.068), SOS (β = - 0.024) as well as stiffness-index (β = - 0.056) and CE were present, while fracture risk was positively associated with CE (β for high = 1.28 and moderate = 2.54 vs. low fracture risk). Interactions between BUA and sex as well as between SOS and age were detected in the models for CE. Furthermore, there was an inverse relation between fracture risk and NSA that was restricted to the moderate risk (β for moderate vs. low fracture risk = - 0.60). There were no significant associations between QUS parameters and alpha angle.

CONCLUSIONS

In the general population, several associations between QUS-based bone properties or fracture risk and hip geometry are present. Less dysplastic hips had a lower stiffness-index and a higher fracture risk, whereas more valgus hips had a lower fracture risk.

Relationship between developmental dislocation of the hip in infant and acetabular dysplasia at skeletal maturity

Previous reports demonstrated 8-60% patients treated for developmental dislocation of hip (DDH) in infancy have residual acetabular dysplasia (AD) at skeletal maturity. AD patients reportedly exhibit abnormal morphology of the pelvis, high rates of comorbid spinal congenital anomalies and high bone mineral density. These physical findings suggest that AD patients have genetic background. We examined the percentage of AD patients with hip pain at skeletal maturity having a history of DDH in infancy and the correlation between the severity of AD at skeletal maturity and history of DDH treatment to investigate the relationship between AD and DDH.A total of 245 patients were radiographically examined for any history of DDH treatment in infancy. The study included 226 women and 19 men with a mean age at examination of 40.7 years (range 17-59 years).Eighty-eight patients (36%) had a history of DDH treatment (DDH group) and the remaining 157 patients (64%) had no history of DDH treatment (non-DDH group). The average age was lower and acetabular angle was larger in the DDH group. There was a significant increasing trend of the percentage of DDH patients associated with the severity of AD classified with CE, acetabular angle, and acetabular roof angle.Our data suggest that there are several AD patients without a history of DDH in Japan, and AD in patients without a history of DDH has different characteristics from AD in patients with a history of DDH.

Impaired ossification coupled with accelerated cartilage degeneration in developmental dysplasia of the hip: evidences from μCT arthrography in a rat model

Background

Developmental dysplasia of the hip (DDH) always leads to cartilage degeneration and osteoarthritis of the hip joint. However, the diagnosis of early cartilage degeneration in DDH is still a clinical challenge. This study aims to investigate the dynamic changes of bone and cartilage in the hip of a rat model of DDH and to explore the potential application of microcomputed tomography (μCT) arthrography to detect early cartilage degeneration in DDH.

Methods

Newborn Wistar rats were used to induce DDH by hindlimb swaddling. The bone and cartilage of the hip in model and control group were analyzed by μCT arthrography and histology examination at postnatal day 10, week 4, 6 and 8.

Results

Hip dysplasia developed with age, became obvious at postnatal week 6 and further progressed at week 8. μCT analysis showed that bone mineral density (BMD) and bone volume density (bone volume over total volume, BV/TV) of the femoral head and neck region (FHNR) in model group were both significantly lower than those in control group, and they increased dramatically from postnatal week 4 to week 6 but maintained at a similar level at week 8. Contrast-enhanced μCT (CE-μCT) arthrography and histology data showed age-dependent increase in cartilage attenuation (CA) and decrease in safranin O staining intensity (SI) in model group, respectively. Moreover, the model group revealed remarkably higher CA and lower SI than control group, respectively. In addition, significant changes of CA and SI were both observed from postnatal week 6 to week 8 in model group. A strong linear correlation (r² = 0.789, P <0.001) was found between CA and SI in model group. Furthermore, BMD was negatively correlated with SI (t = -2.683, P <0.05), whereas specific bone surface (bone surface over bone volume, BS/BV) was positively correlated with SI (t =4.501, P <0.01), in model group.

Conclusions

Impaired ossification coupled with continuous loss of sGAG in cartilage matrix was found in the dysplasia hip during the disease progression of DDH. Cartilage degeneration in the dysplasia hip may occur early at childhood, accelerated with age and become irreversible at young adult stage. All these abnormal changes could be quantitatively assessed by μCT arthrography.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-339) contains supplementary material, which is available to authorized users.