Residual dysplasia after successful Pavlik harness treatment: early ultrasound predictors

Ultrasonographic findings in hips with a positive Ortolani sign and their relationship to Pavlik harness failure

BACKGROUND

In developmental dysplasia, Pavlik harness treatment of hips with a positive Ortolani sign fails in up to 40% of such patients; however, no study has described factors for failure associated with ultrasonographic parameters. The goal of this study was to describe unique ultrasonographic markers in hips with a positive Ortolani sign that are associated with Pavlik harness failure.

METHODS

A retrospective review was performed of all patients less than six months old who were treated for developmental dysplasia of the hip with a Pavlik harness from 1991 to 2005 at a single institution. Inclusion criteria for this study were patients with a hip that was dislocated but reducible (a positive Ortolani sign), treatment with a Pavlik harness, and an ultrasound examination performed within four weeks after the initiation of treatment. The initial coronal ultrasound studies were graded with use of the Graf classification, the percentage of femoral head coverage, labral morphology, and two new measurements: superior femoral head displacement relative to the labrum and total femoral head displacement.

RESULTS

Eighty-five patients with 115 hips fitting the inclusion criteria were identified. Pavlik harness treatment was successful in seventy-two hips (63%) and failed in forty-three hips (37%). Increased beta angle, decreased femoral head coverage, an inverted labrum, decreased superior femoral head displacement relative to the labrum, and decreased total femoral head displacement were significantly correlated with Pavlik harness failure (p < 0.001 for all). A finding of 0 degrees of superior femoral head displacement relative to the labrum was seen in 98% of the hips with successful Pavlik harness treatment. Total femoral head displacement of less than -30 degrees was found in 89% of the hips with a failure of Pavlik harness treatment.

CONCLUSIONS

We identified two new objective measurements on static ultrasound examinations of the hip that are associated with the outcome of Pavlik harness treatment in patients with developmental dysplasia and a positive Ortolani sign. A femoral head positioned below the labrum is strongly associated with success of the Pavlik harness treatment, whereas a hip with a femoral head that is located substantially superior and lateral to the labrum is associated with Pavlik harness treatment failure. The presence of a deficient cartilaginous anlage and an inverted labrum may provide a pathoanatomical explanation for Pavlik harness treatment failure.

Predictive factors for unsuccessful treatment of developmental dysplasia of the hip by the Pavlik harness

BACKGROUND

The Pavlik harness is a widely used and effective means of initial treatment of developmental dysplasia of the hip (DDH), but some hips fail to stabilize with the use of harness and avascular necrosis (AVN) of the femoral head can occur. Predictive factors for unsuccessful Pavlik harness treatment should be determined for appropriate indication of the treatment and prevention of AVN.

METHODS

The outcome of Pavlik harness treatment for DDH was retrospectively examined in 221 hips of 210 patients who were treated initially at our institution and followed up for at least 1 year after the application of the harness. Univariate analysis was performed to determine predictors for failure of reduction and for the incidence of AVN by using the Mann-Whitney U test for continuous variables and the Fisher exact test or the Pearson test for categorical variables. Next, independent multivariate predictors for the failure of reduction and the incidence of AVN were identified using logistic regression analysis.

RESULTS

One hundred and eighty-one hips were reduced and the overall rate of reduction was 81.9%. AVN that was diagnosed according to the criteria of Salter et al was identified in 16 of the 181 reduced hips and the rate of incidence of AVN was 8.8%. Bilaterality and decreased distance "a," as defined by Yamamuro and Chene, were statistically significant univariate and multivariate risk factors for the failure of reduction. Between them, distance a was the most powerful predictor. Adduction contracture of the hip (abduction with the hips flexed to 90 degrees <60 degrees) was the only significant univariate and multivariate predictor for the incidence of AVN.

CONCLUSIONS

Distance a and adduction contracture of the hip were important predictors for the outcome of Pavlik harness treatment. We concluded that the Pavlik harness is a very safe and effective means of DDH treatment for the hips with abduction > or = 60 degrees and distance a > or = 6 mm.

LEVEL OF EVIDENCE

Therapeutic studies, level III (retrospective study).

To screen or not to screen? A decision analysis of the utility of screening for developmental dysplasia of the hip

BACKGROUND

The United States Preventive Services Task Force recently determined that they could not recommend any screening strategies for developmental dysplasia of the hip. Disparate findings in the literature and treatment-related problems have led to confusion about whether or not to screen for this disorder. The purpose of the present study was to determine, with use of expected-value decision analysis, which of the following three strategies leads to the best chance of having a non-arthritic hip by the age of sixty years: (1) no screening for developmental dysplasia of the hip, (2) universal screening of newborns with both physical examination and ultrasonography, or (3) universal screening with physical examination but only selective use of ultrasonography for neonates considered to be at high risk.

METHODS

Developmental dysplasia of the hip, avascular necrosis, and the treatment algorithm were carefully defined. The outcome was determined as the probability of any neonate having a non-arthritic hip through the age of sixty years. A decision tree was then built with decision nodes as described above, and chance node probabilities were determined from a thorough review of the literature. Foldback analysis and sensitivity analyses were performed.

RESULTS

The expected value of a favorable hip outcome was 0.9590 for the strategy of screening all neonates with physical examination and selective use of ultrasonography, 0.9586 for screening all neonates with physical examination and ultrasonography, and 0.9578 for no screening. A lower expected value implies a greater risk for the development of osteoarthritis as a result of developmental dysplasia of the hip or avascular necrosis; thus, the optimum strategy was selective screening. This model was robust to sensitivity analysis, except when the rate of missed dysplasia rose as high as 4/1000 or the rate of treated hip subluxation/dislocation was the same; then, the optimum strategy was to screen all neonates with both physical examination and ultrasonography.

CONCLUSIONS

Our decision analytic model indicated that the optimum strategy, associated with the highest probability of having a non-arthritic hip at the age of sixty years, was to screen all neonates for hip dysplasia with a physical examination and to use ultrasonography selectively for infants who are at high risk. Additional data on the costs and cost-effectiveness of these screening policies are needed to guide policy recommendations.

Acetabular cartilaginous angle: a new method for predicting acetabular development in developmental dysplasia of the hip in children between 2 and 18 months of age

BACKGROUND

A new method of arthrographic measurement, the acetabular cartilaginous angle (ACA), is described here in an effort to find a simple, reliable, and reproducible measurement that can predict future acetabular development after successful closed reduction of developmental dysplasia of the hip (DDH).

METHODS

A prospective study was conducted for children with DDH who were treated successfully by closed reduction in the authors' institute from 1994 through 2000. The total number of patients who completed the follow-up in our study until full acetabular development or acetabuloplasty was 162, with 234 affected hips. Their age at the time of closed reduction ranged between 2 and 18 months (mean, 7.48 months; SD +/-5.162). There were 135 girls and 27 boys. Frank dislocation of the hip was present in 195 hips, whereas acetabular dysplasia with or without lateralization of the femoral head was seen in 39 hips. The average follow-up was 9.2 years (range, 6-11 years).

RESULTS

Multivariate analysis of 6 variables showed that the mean age and acetabular index at the time of closed reduction were significant to predict later acetabuloplasty, whereas ACA was highly significant. These 3 significant variables together had 96.58% correct prediction. The authors observed that some hips with high acetabular index developed satisfactorily, and other hips with small values required later acetabuloplasties. On the other hand, there was a clear cut value of ACA (20 degrees) under which almost all hips (99.5%) developed satisfactorily and another clear cut value of ACA (24 degrees) above which all hips (100%) needed acetabuloplasty.

CONCLUSIONS

Acetabular cartilaginous angle is considered a reliable measurement to identify hips with DDH that will need later acetabuloplasty after successful closed reduction. The acetabular index is important in monitoring acetabular development, and reaching a value of less than 30 degrees 2 years after closed reduction is considered a good sign of acetabular development.

Correlation of femoral head coverage and Graf alpha angle in infants being screened for developmental dysplasia of the hip

Ultrasonography has become accepted as a useful imaging modality in the early detection of developmental dysplasia of the hip (DDH). The purpose of this study was to investigate the extent to which ultrasonographic measurements of femoral head coverage correspond to the categories of hip maturity defined by Graf's angle alpha. The infants in this study (1,037 infants, 2,034 hips) were examined as part of an ultrasound screening program for detecting DDH. We found that femoral head coverage is positively correlated with alpha angle, and we also found upper and lower threshold values of femoral head coverage (51% and 39%), such that all hips having these values or beyond had mature or pathological development, respectively. For the detection of hips having mature development, this provided a specificity of 100% (by definition) and a sensitivity of 82.6%. For hips having pathological development, specificity was 100% and sensitivity was 79.2%.