Acetabular development after reduction in developmental dislocation of the hip

Factors influencing outcomes of pelvic osteotomy for residual acetabular dysplasia following closed reduction in patients with developmental dysplasia of the hip

To investigate the factors influencing outcome of pelvic osteotomy (PO) for residual acetabular dysplasia (RAD) following closed reduction (CR) in patients with developmental dysplasia of the hip (DDH). We retrospectively reviewed 91 patients (95 hips) with DDH who underwent PO for RAD. Tönnis grade, Acetabular index, Center Edge Angle, Reimer's Index (RI), and avascular necrosis of the femoral head (AVN) were assessed. Hips were divided into satisfactory (Severin I/II) and unsatisfactory group (Severin III/IV). Finally, 87 hips (91.5%) had satisfactory and 8 (8.5%) unsatisfactory outcomes. The RI before PO was significantly higher in unsatisfactory (49.6 ± 9%) than in satisfactory group (30.6%±11.8%). All patients without AVN had satisfactory outcome, while it was 78.9% of patients with AVN. Logistic regression analysis showed that higher AVN grade and RI before PO were risk factors for unsatisfactory outcome. Satisfactory outcome was obtained in all hips with RI < 33% before PO, while it was 79.5% if RI > 33% before PO (79.5%). There was no difference in the satisfactory rate between patients undergoing open reduction (66.7%) and those not undergoing (83.3%). The rate of satisfactory outcome in patients undergoing femoral osteotomy (63.6%) was lower than those without it (100%). In patients with RAD following CR, good outcome can be expected after PO alone. AVN and preoperative RI > 33% are risk factors for poor outcome. Additional open reduction and femoral osteotomy do not significantly improve outcome of PO in patients with preoperative RI > 33%.

When to Combine Acetabular Osteotomy in Patients With Proximal Femoral Deformity Causing Residual Hip Dysplasia/Subluxation After Reduction of Developmental Dysplasia of the Hip

BACKGROUND

After the successful reduction of developmental dysplasia of the hip, residual hip dysplasia may persist and lead to early osteoarthritis. Femoral and/or acetabular osteotomy has been used to address this problem. The purpose of this study is to determine the indication of femoral versus combined femoral-acetabular osteotomy in the management of residual hip dysplasia.

METHODS

Fifty-five patients with unilateral dislocated-type dysplasia of the hip, who had residual hip dysplasia after reduction, underwent femoral osteotomy with or without acetabular osteotomy before 8 years of age, and were followed for more than 2 years and over 8 years of age, were the subjects of this retrospective study. Twenty-eight patients underwent femoral osteotomy only at a median age of 34 months (group F), and 27 underwent combined femoral-Dega osteotomy at a median age of 49 months (group C). Seventeen patients in group F and 4 in group C had an additional osteotomy due to persistent hip dysplasia. Acetabular index (AI), lateral center-edge angle, and center-head distance difference were measured on serial radiographs. The z-value of AI (Z AI ) was calculated. At the latest follow-up, patients in group F with Severin I/II who did not have an additional osteotomy were considered satisfactory, and patients with Severin III/IV or those who had an additional osteotomy were considered unsatisfactory. Preoperative variables were tested for the difference between satisfactory and unsatisfactory cases. Receiver operating characteristic analysis was performed to delineate a cutoff value of a significant parameter dividing the outcome.

RESULTS

AI and Z AI before index osteotomy were significant parameters predicting a satisfactory outcome in group F. Receiver operating characteristic analysis returned a cutoff value of Z AI 2.6 (Area Under the Curve=0.86, P =0.001). Eight of 12 cases (66.7%) with Z AI <2.6 in group F achieved a satisfactory outcome, whereas only 2 of 14 cases with Z AI ≥2.6 in group F did ( P =0.02).

CONCLUSION

Z AI 2.6 may serve as a threshold to combine acetabular osteotomy with femoral osteotomy in the management of residual hip dysplasia before 8 years of age.

LEVEL OF EVIDENCE

Therapeutic III.

Teardrop and sourcil line (TSL): a novel radiographic sign that predicts residual acetabular dysplasia (RAD) in DDH after closed reduction

BACKGROUND

Residual acetabular dysplasia (RAD) is a major problem of developmental dysplasia of the hip (DDH) after closed reduction (CR). Several parameters have been investigated as ways of predicting RAD; however, prediction of RAD remains controversial. The purpose of this study was to evaluate the radiographic sign of teardrop and sourcil line (TSL) in pediatric patients with DDH to enable prediction of RAD after CR.

METHODS

One hundred and twenty-five hips with DDH treated with CR and followed up for at least 2 years were included in this study. The mean age at CR was 18.3 months (range, 9 to 32 months) and the average follow-up time was 50.2 months (range, 24 to 89 months). The acetabular index (AI) was measured at different time points. The cases were divided into two groups according to whether TSL became continuous or not. The relationships among TSL, AI and RAD were analyzed.

RESULTS

The RAD incidence was 73.6% (92/125) at the last follow-up. AI at CR and TSL were the prognostic factors for RAD (P=0.017 and 0.001, respectively). Thirty-four hips showed a continuous TSL. There was a lower RAD rate in the TSL continuous group (P<0.001). There was no statistical difference in the AI at CR between the TSL continuous and discontinuous groups; however, the level of AI after CR was lower in the TSL continuous group. The TSL of 74% (20/27) hips became continuous after acetabular osteotomy surgery.

CONCLUSIONS

The TSL continuous group had a lower AI and incidence of RAD than the discontinuous group. The TSL can be a predictive factor of RAD in DDH after CR and restore the continuous of TSL maybe a potential parameter that can help surgeons to make a judgment intra-operation.

Residual Acetabular Dysplasia in the Reduced Hip

BACKGROUND

Residual acetabular dysplasia occurs in up to a third of patients treated successfully for developmental dysplasia of the hip (DDH) and has been found to be a significant risk factor for early hip osteoarthritis (OA).

DISCUSSION

Age at the time of initial reduction and the initial severity of DDH have been linked to residual acetabular dysplasia. An anteroposterior pelvic radiograph is the main diagnostic modality, but MRI also provides valuable information, particularly in equivocal cases. The literature supports intervening when significant residual acetabular dysplasia persists at 4-5 years of age, and common surgical indications include acetabular index (AI) > 25°-30°, lateral center-edge angle (LCEA) < 8°-10°, and a broken Shenton's line on radiographs; and a cartilaginous acetabular angle (CAI) > 18°, cartilaginous center-edge angle (CCE) < 13°, and/or the presence of high-signal intensity areas on MRI. Surgical options include redirectional pelvic osteotomies and reshaping acetabuloplasties, which provide comparable radiographic and clinical results.

CONCLUSION

RAD is common after treatment of DDH and requires regular follow-up for diagnosis and appropriate management to decrease the long-term risk of OA. Long-term outcomes of patients treated with pelvic osteotomies are generally favorable, and the risk of OA can be decreased, although the risk of total hip replacement in the long-term remains.

The lateral edge and sourcil acetabular indices for surgical decision-making in developmental dysplasia of the hip

PURPOSE

The acetabular index (AI) is a radiographic measure that guides surgical decision-making in developmental dysplasia of the hip (DDH). Two AI measurement methods are described; to the lateral edge of the acetabulum (AI-L) and to the lateral edge of the sourcil (AI-S). The purpose of this study was to determine the level of agreement between AI-L and AI-S on the diagnosis and degree of acetabular dysplasia in DDH.

METHODS

A total of 35 patients treated for DDH with Pavlik harness were identified. The AI-L and AI-S were measured on radiographs (70 hips) at two and five years of age. AI-L and AI-S were then transformed relative to published normative data (tAI-L and tAI-S). Bland-Altman plots, linear regression and heat mapping were used to evaluate the agreement between tAI-L and tAI-S.

RESULTS

There was poor agreement between tAI-S and tAI-L on the Bland-Altman plots with wide limits of agreement and no proportional bias. The two AI measurements were in agreement as to the presence and severity of dysplasia in only 63% of hips at two years of age and 81% at five years of age, leaving the remaining hips classified as various combinations of normal, mildly and severely dysplastic.

CONCLUSION

AI-L and AI-S have poor agreement on the presence or degree of acetabular dysplasia in DDH and cannot be used interchangeably. Clinicians are cautioned to prudently evaluate both measures of AI in surgical decision-making.

LEVEL OF EVIDENCE

I.

Variables influencing the pelvic radiological evaluation in children with developmental dysplasia of the hip managed by closed reduction: a multicentre investigation

PURPOSE

This study aims to evaluate (1) the probability to achieve normal pelvic radiographs in children with developmental dysplasia of the hip (DDH) treated by closed reduction and (2) the amount of time needed to achieve normal pelvic radiographs and to assess what factors influence both probability and time to achieve normal radiographic parameters following CR and spica cast immobilization for DDH.

METHODS

We retrospectively reviewed 436 patients (393 girls, 43 boys; 507 hips) with DDH treated by closed reduction (CR). Tönnis grade, AVN, acetabular index (AI), centre-edge angle (CEA), and Severin radiographic grade were evaluated on plain radiographs. Criteria to rate pelvis radiographs as normal were established. Cox regression was used to evaluate the factors influencing the probability and the time to achieve normal radiographs.

RESULTS

According to our criteria, 167 hips (32.9%) achieved normal radiographic parameters during follow-up. The overall amount of time to achieve normal pelvis radiographs was 36.1 ± 15.5 months. Patients older than 24 months of age at the time of CR needed longer time to achieve normal radiographic parameters (55.2 ± 28 months) compared with other age groups. Cox regression analysis suggested the overall cumulative probability of recovery increased by 46% at five years following CR, then it tended to plateau with an annual increase less than 5%. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN were risk factors for reduced probability of achieving normal radiographic parameters.

CONCLUSIONS

The cumulative probability of achieving normal pelvis radiographs increases linearly during the first five years following CR, then it tends to plateau. Age older than 24 months and Tönnis grade III and IV are associated with longer time to achieve normal radiographic parameters. Age older than 24 months, bilateral dislocation, pre-operative AI greater than 40°, and AVN are risk factors for reduced probability of achieving normal radiographic parameters in children with DDH treated by closed means.

Comparison of Open Reduction Alone and Open Reduction Plus Pemberton Osteotomy Techniques in the Treatment of Developmental Hip Dysplasia at Walking Age

Objective

Open reduction (OR) alone and OR plus Pemberton periacetabular osteotomy (PPO) techniques are commonly used in the treatment of developmental dysplasia of the hip at walking age. However, discussions on the timing of acetabular osteotomy are still ongoing. The aim of the present study was to compare the results of patients who underwent Ferguson OR (FOR group) and OR plus PPO group.

Materials and Methods

Between 2008 and 2017, we performed surgery on the hips, which we thought were used for closed reduction but could not be reduced as closed, or that the reduction was not stable. Patient follow-up was ≥12 months. The study included 75 hips of 57 patients of which 20 (26.7%) patients with FOR and 55 (73.3%) patients with PPO. Preoperative and postoperative acetabular indices (AIs), additional surgical intervention rates, and avascular necrosis (AVN) rates were compared. The Kalamchi-McEwen classification system was used to evaluate AVN.

Results

The average age of the patients was 12.38 (9-14) months. The mean follow-up period was 38.95 (12-140) months. AVN developed in 21 (24%) hips (6 (8%) type 1, 13 (17.3%) type 2, and 2 (2.7%) type 3). AVN developed in 7 (35%) hips in the FOR group and 14 (25.5%) hips in the PPO group. No statistically significant difference was found between the two groups (p=0.416). Revision surgery was performed in 2 (3.7%) cases of the PPO group and 6 (31.5%) cases of the FOR group. Statistically, the PPO group had less revision surgery (p=0.004). The PPO group had an AI of 13.33° (5°-27°) that was significantly lower (p<0.001) than that of 27.98° (18.39°) of the FOR group.

Conclusion

Ferguson and Pemberton techniques are current and effective in the treatment of patients with developmental hip dysplasia at walking age. There was no significant difference between the two groups when examined from the point of view of AVN, but the results of PPO surgery were found to be better with respect to AI and revision surgery.

Predicting acetabular growth in developmental dysplasia of the hip following open reduction after walking age

BACKGROUND

Acetabular dysplasia of the hip following open reduction can complicate the treatment of developmental dysplasia of the hip (DDH). The purposes of this retrospective study were to investigate the long-term results of open reduction performed via an extensive anterolateral approach for DDH after walking age and to predict acetabular development using postoperative radiographs and arthrograms.

METHODS

From 1973 to 2001, we performed open reduction for 131 hips in 119 pediatric patients with DDH after failed closed reduction. Of these, 85 hips of 73 patients who underwent arthrography at 5 years old were followed-up radiologically until skeletal maturity. Mean age at the time of surgery was 17 ± 4.6 months (range, 10-33 months), and mean age at final survey was 19 ± 5.7 years (range, 14-33 years). Mean follow-up time was 17.7 ± 5.8 years (range, 13-32 years). Groups with satisfactory outcomes (66 hips) and unsatisfactory outcomes (19 hips) according to the Severin classification were compared. Factors predicting acetabular development were identified using univariate and multiple logistic analyses.

RESULTS

Univariate analysis showed a significant between-group difference in acetabular index (AI) at 2 months postoperatively, and in center-edge (CE) angle, cartilaginous AI (CAI), and cartilaginous CE angle at 5 years old (p < 0.05 each). In multiple logistic regression analysis, CAI at 5 years old represented a predictor of acetabular development after open reduction for DDH (odds ratio, 1.81; 95% confidence interval (CI), 1.04-3.13; p < 0.05). Area under the receiver operating characteristic curve for CAI at 5 years old was 0.93 (95%CI, 0.85-1.0), and the optimal cut-off was 10° (81.8% sensitivity, 92% specificity).

CONCLUSIONS

A CAI ≥10° on hip arthrograms at 5 years old may offer a useful indicator of the need for corrective surgery following open reduction after walking age.

Prognostication in Developmental Dysplasia of the Hip Using the Ossific Nucleus Center Edge Angle

BACKGROUND

The aim of this paper was to determine the prognostic potential of the ossific nucleus center edge angle (ONCEA) in patients below 5 years of age treated for developmental dysplasia of the hip (DDH) to predict final outcome and the need for a secondary procedure.

METHODS

The interobserver and intraobserver reliability was calculated using the intraclass correlation coefficient for measurement of the ONCEA. The ONCEA was divided a priori into 3 groups: group A≥10 degrees, group B -9 to 9 degrees, and group C ≤-10 degrees. Final outcome was measured using the McKay score and Severin classification. The presence of osteonecrosis was recorded at final follow-up.

RESULTS

One hundred one patients with 133 dislocated hips underwent closed or open reduction for DDH. Mean age at presentation was 19 months with a mean age at final follow-up of 12.4 years. A significant difference was shown in a comparison of the 3 ONCEA groups using the McKay score, Severin classification, and need for a secondary procedure. Eighty seven of the 101 patients underwent ONCEA reliability measurements. The ONCEA was shown to have a mean intrarater reliability of 0.89, and a mean interrater reliability of 0.77.

CONCLUSIONS

The ONCEA is a reliable measurement in predicting medium-term outcome of the hip post reduction in children under the age of 5 years with DDH and might be useful as a predictor for a secondary procedure before the age of 5 years.

LEVEL OF EVIDENCE

Level III-prognostic case control study.

CLINICAL RELEVANCE

This case control study shows the importance of measuring the ONCEA within 6 months of removing the final cast after reduction of a dislocated hip and its implications for further management and outcome.

Acetabular index is the best predictor of late residual acetabular dysplasia after closed reduction in developmental dysplasia of the hip

PURPOSE

Our objective was to find the best predictor of late residual acetabular dysplasia in developmental dysplasia of the hip (DDH) after closed reduction (CR) and discuss the indications for secondary surgery.

METHODS

We retrospectively reviewed the records of 89 patients with DDH (mean age 16.1 ± 4.6 months; 99 hips) who were treated by CR. Hips were divided into three groups according to final outcomes: satisfactory, unsatisfactory and operation. The changes in the acetabular index (AI), centre-edge angle of Wiberg (CEA), Reimer's index (RI) and centre-head distance discrepancy (CHDD) over time among groups were compared. The power of predictors for late residual acetabular dysplasia of AI, CEA, RI and CHDD at different time points was analysed by logistic regression analysis. Receiver operating characteristics (ROC) curve analysis was used to determine cutoff values and corresponding sensitivity, specificity and diagnostic accuracy for these parameters.

RESULTS

Both AI and CEA improved in all groups of patients following CR. In the satisfactory group, AI progressively decreased until seven to eight years, while CEA increased until nine to ten years (P < 0.05). In the unsatisfactory group, AI and CEA ceased to improve three and two years after CR, respectively (P < 0.05). CEA and RI were significantly better in the satisfactory group compared with the unsatisfactory group at all time points (P < 0.05). Following CR, both RI and CHDD remained stable over time in all groups. Final outcome following CR could be predicted by AI, CEA and RI at all time points (P < 0.01). Cutoff values of AI, CEA and RI were 28.4°, 13.9° and 34.5%, respectively, at one year and 25°, 20° and 27%, respectively, at two to four years post-CR. A total of 80-88% of hips had an unsatisfactory outcome if AI > 28.4° and >25 at one and two to four years following CR, respectively. However, if CEA was less than or RI was larger than the cutoff values at each time point, only 40-60% of hips had an unsatisfactory outcome. Mean sensitivity (0.889), specificity (0.933) and diagnostic accuracy (92.1%) of AI to predict an unsatisfactory outcome were significantly better compared with CEA (0.731; 0.904; 78.2%) and RI (0.8; 0.655; 70.8%) (P < 0.05).

CONCLUSIONS

Satisfactory and unsatisfactory hips show different patterns of acetabular development after reduction. AI, CEA and RI are all predictors of final radiographic outcomes in DDH treated by CR, although AI showed the best results. AI continues to improve until seven years after CR in hips with satisfactory outcomes, while it ceases to improve three to four years after CR in hips with unsatisfactory outcomes. According to our results, surgery is indicated if AI >28° 1 year following CR or AI >25° two to four years after CR. CEA and RI should be used as a secondary index to aid in the selection of patients requiring surgery.

The management of residual acetabular dysplasia: updates and controversies

Residual acetabular dysplasia is a frequent cause of secondary osteoarthritis of the hip and its management is still controversial. The aim of this review is to describe residual acetabular dysplasia, to estimate the age limit above which surgical management is needed, and to emphasize the role of assistive imaging in evaluating predictive parameters for future acetabular development. A decision-making algorithm is presented.

Acetabular Remodeling and Role of Osteotomy After Closed Reduction of Developmental Dysplasia of the Hip

BACKGROUND

The purposes of this study were to evaluate acetabular remodeling after closed reduction of developmental dysplasia of the hip (DDH) and to delineate the role of osteotomy.

METHODS

Eighty-four hips with DDH treated with closed reduction and followed until the patient was 8 years of age or older were included in this study. The mean age at closed reduction was 14.0 months (range, 3 to 30 months) and that at the latest follow-up visit was 12.7 years (range, 8.0 to 24.7 years). Osteotomy was performed in 26 hips (31%) during the follow-up period, at an average age of 2.8 years (range, 2.0 to 5.8 years). The acetabular index (AI) and center-edge angle (CEA) were measured, and osteonecrosis was graded. The treatment outcome was evaluated as satisfactory (Severin grade I or II) or unsatisfactory (III or IV). We retrospectively analyzed the associations among radiographic parameters, performance of osteotomy, grade of osteonecrosis, and final outcome.

RESULTS

A satisfactory outcome was observed in 67 (80%) of the 84 hips. An osteotomy was not performed in 30 of 34 hips with an AI of <32° and a CEA of >14° at the age of 3 years, and 28 (93%) of these 30 hips showed a satisfactory outcome. Of the 33 hips with an AI of ≥32° and a CEA of ≤14° at the age of 3 years, the 20 that had undergone an osteotomy showed a higher proportion of satisfactory outcomes than the 13 hips that had not (p = 0.01). Three of the 4 hips that showed an unsatisfactory outcome following an osteotomy had an AI of ≥34° at 1 year post-osteotomy. Grade-II, III, or IV osteonecrosis, according to the Bucholz-Ogden classification, developed in 10 of the 84 hips, and these 10 hips had a higher proportion of unsatisfactory outcomes than did those that developed no or grade-I osteonecrosis (p = 0.004).

CONCLUSIONS

Hips with DDH showing poor acetabular remodeling after closed reduction may benefit from osteotomy. The AI and CEA at the age of 3 years can serve as one of the guidelines for osteotomy. Continued surveillance for acetabular remodeling is required even after osteotomy.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Comparison of open reduction alone and open reduction plus Dega osteotomy in developmental dysplasia of the hip

In the treatment of developmental dysplasia of the hip, concentric reduction of the femoral head into the acetabular cavity plays a key role in the natural development of the acetabulum. However, there is still debate on the need for additional acetabular osteotomies and their timing. In this study, we compared open reduction (OR) alone with OR plus Dega osteotomy for acetabular index (AI) development. Twenty patients, 10 in each group, who underwent either OR alone or OR plus Dega osteotomy were studied retrospectively. All patients were diagnosed with developmental dysplasia of the hip and none of them received treatment previously. Preoperative, early postoperative, and follow-up radiographs were gathered, radiological grading was performed according to Tönnis, and AI angles were measured. The OR group had a mean age of 24.5 months, whereas the Dega group had a mean age of 24.8 months. The mean follow-up period of the OR group and Dega group was 57.8 and 66.6 months, respectively. In the OR group, the initial mean AI was 37.5° whereas in the Dega group it was 46°. After the follow-up, despite the acetabular development in the OR group being twice as fast, the final mean AI was 25.5, whereas it was 15.9 in the Dega group. The difference was statistically significant (P<0.05). Using Tönnis' definition, the Dega group ended up with 70% normal hips, 20% mild dysplasia, and 10% severe dysplasia, whereas the OR group had 20% normal hips, 30% mild dysplasia, and 50% severe dysplasia at the final visit. There was no correlation between the initial radiological grading of dislocation and the final result. OR plus Dega osteotomy is a good option to regain acetabular coverage over the femoral head. It provides better radiographic results after a 5-year follow-up period in patients with a mean age of 25 months. OR alone should not be performed unless the child had mildly dysplastic acetabulum according to Tönnis' definition.

Early predictors of acetabular growth after closed reduction in late detected developmental dysplasia of the hip

This study evaluates improvement of the acetabular index (AI) in patients with developmental dysplasia of the hip at 4 years after closed reduction, and determines the association between the final AI and a set of factors. Sixty-two patients (74 hips) treated with closed reduction were categorized into three groups according to age: group A (0-12 months, 18 hips), group B (13-18 months, 24 hips), and group C (>18 months, 32 hips). There was no difference in AI among the three groups before reduction (P=0.293). In groups A and C, the AI decreased significantly over time until 3 years after reduction and no differences were observed between the time points of 3 and 4 years. At 4 years after reduction, the AI of group C was significantly higher than that of groups A (P<0.001) and B (P=0.012). The overall AI improvement rate was 28.63%. The AI improvement rate of group A was significantly higher than that of group C (P=0.005). Pearson correlation analysis indicated no correlation between center-head distance discrepancy and the final AI (P=0.811). Linear regression suggested that age and initial AI correlated significantly with the final AI (R=0.617, F=15.031, P<0.001). Other factors, such as sex, center-edge angle of Wiberg, bilaterally involved, and avascular necrosis of the femoral head, showed no correlations with the final AI (P>0.05). According to the coefficients, initial AI (β1=0.432, P<0.001) had greater effect than age (β2=0.197, P=0.023) on the final AI. In conclusion, the AI decreases in all patients after reduction and stabilizes at 3 years after reduction. The AI improvement rate is correlated negatively with age. Age and initial AI are early predictors of the progress of AI after closed reduction in developmental dysplasia of the hip patients.

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.