Échographie de la hanche néonatale : bilan initial et suivi thérapeutique

Pubofemoral distances correlate to acetabular morphology and sonological instability in screening for hip dysplasia

Aims

The present study seeks to investigate the correlation of pubofemoral distances (PFD) to α angles, and hip displaceability status, defined as femoral head coverage (FHC) or FHC during manual provocation of the newborn hip < 50%.

Methods

We retrospectively included all newborns referred for ultrasound screening at our institution based on primary risk factor, clinical, and PFD screening. α angles, PFD, FHC, and FHC at follow-up ultrasound for referred newborns were measured and compared using scatter plots, linear regression, paired t-test, and box-plots.

Results

We included 2,735 newborns, of whom 754 received a follow-up hip ultrasound within six weeks of age. After exclusion, 1,500 hips were included for analysis. Sex distribution was 372 male and 380 female, and the mean age at examination was 36.6 days (4 to 87). We found a negative linear correlation of PFD to α angles (p < 0.001), FHC (p < 0.001), and FHC during provocation (p < 0.001) with a 1 mm increase in PFD corresponding to a -2.1° (95% confidence interval (CI) -2.3 to -1.9) change in α angle and a -3.4% (95% CI -3.7 to -3.0) change in FHC and a -6.0% (-6.6 to -5.5) change in FHC during provocation. The PFD was significantly higher with increasing Graf types and in displaceable hips (p < 0.001).

Conclusion

PFD is strongly correlated to both α angles and hip displaceability, as measured by FHC and FHC during provocation, in ultrasound of newborn hips. The PFD increases as the hips become more dysplastic and/or displaceable.

Natural progression of the pubofemoral distance with age and its correlation with future acetabular index

OBJECTIVES

This study investigated the progression of pubofemoral distance (PFD) with age and assessed the correlation between PFD and late acetabular index (AI) measurements.

METHODS

This prospective observational study was conducted between January 2017 and December 2021. We enrolled 223 newborns who underwent the first, second, and third hip ultrasounds, and pelvis radiograph at a mean age of 18.6 days, 3.1 months, 5.2 months, and 6.8 months, respectively. The difference between PFD measured at serial ultrasounds and the correlation with AI were analyzed.

RESULTS

The PFD increased significantly (p < 0.001) at serial measurements. The mean PFD at the first, second, and third ultrasounds were 3.3 (2.0-5.7), 4.3 (2.9-7.2), and 5.1 (3.3-8.0) mm, respectively. The PFD at three ultrasounds were all significantly (p < 0.001) and positively correlated with AI, with the Pearson correlation coefficients being 0.658, 0.696, and 0.753 for the first, second, and third ultrasounds, respectively. Using AI as reference, the diagnostic ability of PFD was calculated by the areas under the receiver operating characteristic curve, which was 0.845, 0.902, and 0.938 for the first, second, and third PFD, respectively. For the first, second, and third ultrasounds, PFD cutoff values of ≥ 3.9, ≥ 5.0, and ≥ 5.7 mm, respectively, yielded the greatest sensitivity and specificity in predicting late abnormal AI.

CONCLUSION

The PFD naturally progresses with age and is positively correlated with AI. The PFD has potential for predicting residual dysplasia. However, the cutoff for abnormal PFD values may require adjustment according to the patient's age.

KEY POINTS

• The pubofemoral distance measured in hip ultrasonography naturally increases as the infant's hips mature. • The early pubofemoral distance demonstrates a positive correlation with late acetabular index measurements. • The pubofemoral distance may help physicians predict abnormal acetabular index. However, the cutoff for abnormal pubofemoral distance values may require adjustment according to patient's age.

Use of ultrasonography to evaluate early outcomes of reduction in developmental dysplasia of the hip

OBJECTIVE

To compare pubo-femoral distance (PFD) in normal hips and those treated for developmental dysplasia of the hip (DDH) and to investigate the value of ultrasonography from the medial hip in early follow-up of dislocated DDH after reduction.

MATERIALS AND METHODS

This study included 58 infants (49 females) with DDH who presented with 65 dislocated hips (51 unilateral and 7 bilateral). Dislocation was treated by closed reduction for 53 and open reduction for 12 hips. Ultrasonography on the medial side of the hip was performed within 1-2 weeks and 4 weeks after reduction. The distance from the pubic bone to the femoral head (PFD) was measured to assess the reduction and stability of the femoral head and compared to that on the contralateral side (control) in cases of unilateral DDH.

RESULTS

The PFD value for the normal group (2.9 ± 0.4 mm) was significantly less than that for the closed reduction group (4.9 ± 2.8 mm, P<0.001) and that for the open reduction group (4.4 ± 1.6 mm; P=0.02), but no difference in the PFD was observed between the closed reduction and the open reduction groups (P=0.73). Despite successful reduction, the PFD values in the successful reduction group remained higher than those of the normal hips.

CONCLUSION

PFD measurement by ultrasonography of the medial hip can be used to evaluate the effectiveness of reduction procedures in DDH. The clinical implications of post-reduction ultrasound evaluation in the diagnosis and long-term follow-up of outcomes require further research.

Measurement of Pubofemoral Distance in the Diagnosis of Developmental Dysplasia of the Hip: Sensitivity and Specificity

OBJECTIVES

To evaluate the accuracy of measurement of the pubofemoral distance (PFD) for the diagnosis of developmental dysplasia of the hip (DDH), using the Graf method as the reference standard.

METHODS

This was a prospective diagnostic accuracy study evaluating 1980 hips in at-risk neonates. The PFD measurement and the Graf method were performed at the same opportunity, with the hips in the same position (slightly flexed, adducted, and medially rotated).

RESULTS

In our sample, the prevalence of DDH, defined as Graf type IIb or higher, was 15.6%. The mean PFD for dysplastic hips was 3.5 mm (median, 3.3 mm), whereas it was 3.0 mm (median, 2.9 mm) for nondysplastic hips. In both groups, there was a significant overlap between the PFD measurements and the Graf classifications. The PFD cutoff with the largest area under the receiver operating characteristic curve was 3.0 mm, which was found to have a sensitivity and specificity of 63.6 and 62.2%, respectively, with positive and negative predictive values of 31.2 and 71.4%, respectively, for the diagnosis of DDH.

CONCLUSION

Measurement of the PFD shows good overall accuracy for the diagnosis of DDH. However, given its low-positive predictive value, it should not be considered to be a replacement for the Graf method.

Pulvinar and pubic cartilage measurements to refine universal ultrasound screening for developmental dysplasia of the hip: Data from 1896 infant hips

PURPOSE

Screening modalities for Developmental Dysplasia of the Hip (DDH) and indications for treatment of mild forms remain controversial. Ultrasound (US) measurement of the pubofemoral distance (PFD > 6 mm, composed of the pubic cartilage and the pulvinar) can avoid late diagnoses of DDH. A thick pubic cartilage may nevertheless lead to false positives. The purpose of this study was to establish standard measurements of pubic cartilage and pulvinar, through universal US screening, to lower false positive results and thus any overtreatment.

METHODS

This is a single-center observational prospective study conducted from December 2016 to January 2018, on infants who underwent universal US screening for DDH. The only inclusion criterion was an adjusted age between 4 and 12 weeks when US was realized. PFD measurement was made using the Couture and Tréguier method. In addition, thicknesses of pubic cartilage and pulvinar were measured on the same US section, in millimeters.

RESULTS

Nine hundred and forty-eight patients, representing 1896 hips, were included. The average value of pubic cartilage thickness was 1.25 mm ± 0.58 mm, with an upper threshold of 2.39 mm (+1.96σ). The average value of pulvinar thickness was 2.67 mm ± 0.78 mm, with an upper threshold of 4.20 mm (+1.96σ). We found high inter-observer reproducibility in pubic cartilage measurements.

CONCLUSION

Systematic measurements of pubic cartilage and pulvinar may refine therapeutic decision by identifying false positives. Patients with increased PFD due to a thick pubic cartilage >2,39 mm, without an associated pulvinar enlargement (<4,20 mm), could be therefore only monitored and not overtreated.

Establishing reference values for the pubofemoral distance in normal infant medial hips by ultrasound

BACKGROUND

Measuring the pubofemoral distance (PFD) is important for evaluating the effectiveness of hip reduction in the treatment of developmental dysplasia of the hip (DDH). However, reference PFD values have not been established in normal infants.

PURPOSE

To investigate variations in PFD values measured in normal infant medial hips stratified by age, laterality, and gender.

MATERIAL AND METHODS

A total of 240 infants diagnosed with Graf type Ia and/or Graf type Ib hips by ultrasonography were stratified into eight age groups: 0-1 month; 1-2 months; 2-3 months; 3-4 months; 4-5 months; 5-6 months; 6-7 months; and 7-12 months. The bilateral medial hips were scanned with transinguinal ultrasound. The PFD was defined as the distance between the lateral edge of the superior ramus of pubic bone and the medial edge of the femoral head. Inter-observer reproducibility was assessed.

RESULTS

Among the 240 infants, there were 371 Graf type Ia hips and 109 Graf type Ib hips. Mean ± SD bilateral PFD values of eight groups were measured separately. There were no significant differences in mean PFD values for left or right hips (t = 0.946, P = 0.345) or mean bilateral PFD values in male and female infants (t = 1.445, P = 0.149). Mean PFD values increased linearly with age (left: r = 0.680, P < 0.0001; right: r = 0.682, P < 0.0001). Inter-observer reproducibility was excellent.

CONCLUSION

This study established reference PFD values from the medial hip in infants aged 0-12 months. PFD values increased with age, but were not significantly influenced by laterality or gender. These data provide detailed information that can support follow-up of infants treated for DDH.

Suggestion for new 4.4 mm pubo-femoral distance cut-off value for hip instability in lateral position during DDH screening

Background and purpose - Current selective screening algorithms for developmental dysplasia of the hip (DDH) are insufficient. Universal screening programs have been proposed but so far have been deemed too expensive and time consuming. The pubo-femoral distance may solve this problem as a quick, low-cost, highly sensitive, and specific sonographic measurement for DDH, but this has only been validated in the supine position. Therefore we validated pubo-femoral distance (PFD) in the lateral position as an indicator for instability of the hip. Methods - All participants had undergone ultrasonographic diagnostics using the modified Graf technique. In addition, PFD measurements in lateral position were performed. Results were compared between 25 infants who had been treated for DDH because of dysplastic appearance on ultrasound combined with clinical instability and a control group consisting of 100 untreated infants screened for DDH. Sensitivity, specificity, and cut-off points were determined using Receiver operating characteristics (ROC) analysis. Results - We found a mean PFD of 6.8 mm (6.2-7.4) in the treated group with a control group PFD of 3.4 mm (3.3-3.6) (p < 0.005). A PFD value above a threshold of 4.4 mm yielded a sensitivity of 100% and a specificity of 93% for detecting unstable DDH. Interpretation - PFD measured in lateral position was statistically significantly increased in hips of children treated for DDH with Denis Browne hip brace compared with healthy children with unaffected stable hips. Furthermore, the PFD measurement had a high level of sensitivity and specificity at a cut-off value of 4.4 mm. A cut-off value of 6.00 mm has previously been reported as the gold standard in supine position. We suggest that 4.4 mm is used in lateral position.

The pubo-femoral distance decreases with Pavlik harness treatment for developmental dysplasia of the hip in newborns

OBJECTIVE

To evaluate the evolution of the ultrasonographic pubo-femoral distance (PFD) before and after Pavlik harness treatment for developmental dysplasia of the hip (DDH) in newborns.

PATIENTS AND METHODS

Twenty-five patients (16.7 ± 10.4 days; 19 females, six males) diagnosed with DDH and treated using the Pavlik harness were included. Eighteen patients had bilateral, and seven unilateral DDH, with a total of 43 dysplastic hips. The seven non-dysplastic hips in unilateral cases were used for comparison. The PFD was measured in the coronal and axial planes with the hip flexed to approximately 90°, before and after an average of 93 days of treatment. The femoral head coverage was assessed in the coronal plane, and correlated with PFD values.

RESULTS

In dysplastic hips, the mean PFD decreased from 6.1 ± 1.8 mm to 3.0 ± 0.7 mm in the axial (adjusted difference, 2.9 mm; p < 0.01), and from 5.9 ± 2.0 to 3.0 ± 0.6 mm in the coronal plane (adjusted difference 2.7 mm; p < 0.01). The femoral head coverage increased from 30.8 to 62.1%, and the mean differences of femoral head coverage and PFD were significantly correlated (p < 0.001). There was no difference between treated dysplastic and non-dysplastic hips. There was high intra- and inter-observer agreement for PFD measurements.

CONCLUSION

The PFD decreased significantly after DDH treatment using the Pavlik harness in newborns, and showed significant correlation with the femoral head coverage improvement. PFD might be a reliable tool for monitoring DDH treatment in newborns treated using the Pavlik harness.

Congenital dislocation of the hip: optimal screening strategies in 2014

A prospective multi-centre nationwide study of patients with congenital dislocation of the hip (CDH) diagnosed after 3 months of age was conducted with support from the French Society for Paediatric Orthopaedics (Société Française d'Orthopédie Pédiatrique [SoFOP]), French Organisation for Outpatient Paediatrics (Association Française de Pédiatrie Ambulatoire [AFPA]), and French-Speaking Society for Paediatric and Pre-Natal Imaging (Société Francophone d'Imagerie Pédiatrique et Prénatale [SFIPP]). The results showed inadequacies in clinical screening for CDH that were patent when assessed quantitatively and probably also present qualitatively. These findings indicate a need for a communication and educational campaign aimed at highlighting good clinical practice guidelines in the field of CDH screening. The usefulness of routine ultrasound screening has not been established. The findings from this study have been used by the authors and French National Health Authority (Haute Autorité de Santé [HAS]) to develop recommendations about CDH screening. There is an urgent need for a prospective randomised multi-centre nationwide study, which should involve primary-care physicians.

Pubo-femoral distance: an easy sonographic screening test to avoid late diagnosis of developmental dysplasia of the hip

OBJECTIVES

To propose an easy and reproducible sonographic screening test able to avoid late presentation of developmental dysplasia of the hip (DDH).

METHODS

The pubo-femoral distance (PFD) cut-off point was determined on 980 infants who underwent ultrasonography of the hips in comparison with the final diagnosis, based on clinical, ultrasound data and follow-up. PFD reproducibility was tested on 52 hips by both an experienced and an inexperienced radiologist. After teaching this screening method to general radiologists, its impact was evaluated by analysing the rate of late diagnosis in an entire administrative area.

RESULTS

An abnormal PFD threshold above 6 mm gave a sensitivity of 97.4 % for the diagnosis of DDH (271 hips) and a specificity of 84 %. Sensitivity increased to 100 % when taking into consideration children of 1 month or older. The PFD measurement stayed reproducible even in inexperienced hands (k = 0.795). For 3 years, following the extension of screening to all female infants, there was no late diagnosis of DDH in girls in amongst a catchment area of 1 million inhabitants.

CONCLUSIONS

PFD measurement with a threshold for abnormality of 6 mm at the age of 1 month, without asymmetry above 1.5 mm, could eradicate DDH late diagnosis.