Severity Of Developmental Dysplasia Of The Hip Research Articles

EFFECT AND LIMITATION OF PERIACETABULAR OSTEOTOMY FOR ACETABULAR DYSPLASIA CLARIFIED BY 3D FINITE ELEMENT ANALYSIS

Finite element analysis (FEA) has been applied for the biomechanical analysis of acetabular dysplasia, but not for biomechanical studies of periacetabular osteotomy (PAO) or those performing analysis taking into consideration the severity of acetabular dysplasia. This study aimed to perform biomechanical evaluation of changes in stress distribution following PAO and to determine the effect of the severity of developmental dysplasia of the hip (DDH) using three-dimensional FEA.A normal model was designed with a 25° center-edge (CE) angle and a 25° vertical-center-anterior margin (VCA) angle. DDH models were designed with CE and VCA angles each of 10, 0, or −10°. Post-PAO models were created by separating each DDH model and rotating the acetabular bone fragment in the anterolateral direction so that the femoral head was covered by the acetabular bone fragment, with CE and VCA angles each at 25°.Compared to the normal hip joint model, the DDH models showed stress concentration in the acetabular edge and contacting femoral head, and higher stress values; stress increased with decreasing CE and VCA angles. Compared to the DDH models, the post-PAO models showed near-normal patterns of stress distribution in the acetabulum and femoral head, with stress concentration areas shifted from the lateral to medial sides. Stress dispersion was especially apparent in the severe acetabular dysplasia models. PAO provided greater decreases in the maximum values of von Mises stress in the load-bearing area of the acetabulum and femoral head when applied to the DDH models of higher degrees of severity, although the values increased with increasing severity of DDH. PAO is expected to provide biomechanical improvement of the hip joint, although the results also suggest a limitation in the applicability of PAO for the patients with severe acetabular dysplasia.

Ultrasonography in the evaluation of various factors of developmental dysplasia of the hip in infants: Results from a retrospective study in a large hospital of northwest China

BackgroundThe occurrence and development of developmental dysplasia of the hip (DDH) are related to a variety of factors, which have been reported in the literature, but the literature does not mention factors related to the severity of DDH. The purpose of this study is to analyze the related factors of the occurrence and severity of DDH in combination with the Graf ultrasonic diagnostic classification. MethodsThis study was a monocentric retrospective study describing the factors associated with DDH in a large hospital of northwest China. A total of 3046 infants (6092 hips) within 6 months after birth using the Graf method were admitted to our department between 2014 and 2018. We analyzed data of DDH. After reviewing medical charts and diagnostic examination results, we assessed whether factors such as ethnicity, gender, gestational age, birth weight, diagnosis age, maternal age, mode of delivery, fetal presentation, amniotic fluid volume and birth order, had any effect on development of hip. Result① Analysis showed that DDH mostly occurs in female and left hip joint, related to intrauterine fetal presentation, amniotic fluid volume, gestational age, mode of delivery, prenatal weight, and diagnosis age after birth, and the occurrence of DDH is also related to maternal age (All P＜0.05). Ethnicity and first born showed have no obvious correlation with DDH incidence (p = 0.718, 0.147, respectively). ② The strongest correlation was found with amniotic fluid, followed by birth weight. ③ The severity of DDH was correlated with ethnicity, births, prenatal weight, gestational age, diagnosis age and maternal age (All P＜0.05, respectively). ④ There were significant differences in treatment methods, duration and prognosis among different types of DDH. ConclusionsThe occurrence and development of DDH are related to a variety of factors. Ultrasound examination can provide an early assessment of the hip development status of infants and may play an important role in establishing an early clinical diagnosis treatment and monitoring and prognosis.

Variants of Acetabular Deformity in Developmental Dysplasia of the Hip in Young Children

Background. The choice of pelvic reconstruction technique in children with developmental dysplasia of the hip (DDH) has been the subject of discussion for many years and is often determined by personal preferences of a surgeon rather than by X-ray anatomical state of the acetabulum. The variants of its anatomy structure have still not been reflected in the available scientific literature.
 Aim of the study to identify the most typical variants of acetabular deformation in children with varying severity of DDH, based on the X-ray anatomical analysis of structure of the acetabulum.
 Methods. The study was based on the results of examination of 200 patients (200 hip joints) aged 2 to 4 years (3.10.45) with Tnnis grade II-IV DDH. All patients underwent conventional clinical and radiological examination. The latter consisted of hip radiography in several views and computed tomography. We took the values of acetabular index, the extent of acetabulum arch and the presence or the absence of bone oriel as criteria for determination of the most typical variants of acetabular deformation.
 Results. X-ray analysis of anatomical structure of the acetabulum in young children with varying severity of DDH revealed 3 most common variants of acetabular deformity: 1 moderate underdevelopment of the acetabulum arch (AI 35), its shortening and the presence of bone oriel; 2 pronounced underdevelopment of the acetabulum arch (AI 35), its shortening and the presence of bone oriel; 3 pronounced underdevelopment of the acetabulum arch (AI 35), its sufficient length and the absence of bone oriel.
 Conclusion. Suggested supplements to existing Tnnis DDH classification might become basic for choosing the surgical correction technique of the acetabulum in children with different severity of DDH.

The Effect of the Parents’ Socio-Economic Status on the Treatment Process With the Orthopedic Approach in Developmental Dysplasia of the Hip

Aims: Developmental dysplasia of the hip (DDH) is a common multifactorial pediatric disease. Physical examination and ultrasonographic findings are used in the screening. The severity of DDH in 0-6 month-old infants is determined by Graf classification. The severity of DDH and the age of the patient before treatment have been shown to be among the main factors determining the success rate. Socio-economic conditions of the parents also affects the success rate of Pavlik harness treatment. In this study, socio-economic and socio-cultural factors that affect the treatment success of Pavlik harness method were aimed to be determined. Methods: The study was carried out on 66 infants with DDH between the ages of 0-6 months who admitted to the orthopedics and traumatology outpatient clinic between 2018-2020. Interviews were conducted with the families of the infants using the questionnaire technique. Results: All of the patients were given care by their mothers. It has been observed that there is a relationship between the education level and the success of the Pavlik harness. Also, income level of the household and living in rural and urban areas are also associated with Pavlik bandage treatment. Conclusion: Education level, place of residence and monthly income, which are effective on health literacy, have an impact on the skill level required for Pavlik harness usage.

The Effect of Traction before Closed Reduction in Patients with Developmental Dysplasia of the Hip.

Developmental dysplasia of the hip (DDH) with a dislocated hip can be treated with traction before closed reduction (CR). Currently, there is insufficient evidence supporting the use of preoperative traction treatment for a successful CR. The objective of this study was to determine the effect of preoperative traction on the success rate of primary CR in DDH patients with dislocated hips. A retrospective pair-matched study was performed in DDH patients with dislocated hips. Patients with preoperative traction treatment prior to primary CR were matched (based on age and the severity of DDH on the radiograph) to patients without preoperative traction treatment. The primary outcome was the presence or absence of maintained reduction after three weeks. A match was found for 37 hips, which resulted in the inclusion of 74 hips. No significant difference was found in the number of successful reductions after three weeks between the traction group and the control group (31 vs. 33 hips, p = 0.496). Traction treatment did not significantly improve the short-term or mid-term outcomes for closed reduction. Based on these results, we suggest that traction treatment should not be used as standard care for dislocated hips in DDH.

Evaluation of antero-posterior instability of the hip using modified Lequesne's false profile view

BackgroundAccurate evaluation of hip instability is critical for the diagnosis and successful treatment of developmental dysplasia of the hip (DDH). However, dynamic evaluation of hip instability is not well established. This study aimed to use the lateral view from a radiograph to evaluate dynamic antero-posterior hip instability in patients with DDH. MethodsSeventy-four patients (92 hips) with DDH (DDH group) and 46 patients (59 hips) without hip pain and DDH (Control group) were examined. A false profile view (FPV) according to Lequesne was taken at standard and 90° flexion with the hip of interest defined as functional FPV; the translation of the center of the femoral head (CFH) obtained from the functional FPV was measured. As a validation test, we measured the anterior translation of the CFH using ultrasonography (US). ResultsThere was a significant difference between the two groups in the translation of the CFH (p < 0.01). The degree of CFH translation depended on the severity of DDH (lateral center edge angle, r = −0.56, p < 0.01; vertical center anterior margin angle, r = −0.57, p<0.01) and lateralization of the femoral head (head lateralization index, r = 0.54, p < 0.01). There was a significant correlation between functional FPV and US measurements (r = 0.71, p < 0.01). ConclusionThe present study confirmed that antero-posterior hip instability in DDH patients can be detected using functional FPV. Our novel measurement, as a new method for assessing hip instability, may be useful for evaluating hip dynamic instability in diagnosing the etiology, and determining and evaluating the treatment for DDH at lower cost and improved accessibility.

Robotic-arm assisted THA can achieve precise cup positioning in developmental dysplasia of the hip : a case control study.

AimsThis study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH).MethodsThe study analyzed a consecutive series of 69 patients who underwent robotic-arm assisted THA between September 2018 and December 2019. Of these, 30 patients had DDH and were classified according to the Crowe type. Acetabular component alignment and 3D positions were measured using pre- and postoperative CT data. The absolute differences of cup alignment and 3D position were compared between DDH and non-DDH patients. Moreover, these differences were analyzed in relation to the severity of DDH. The discrepancy of leg length and combined offset compared with contralateral hip were measured.ResultsThe mean values of absolute differences (postoperative CT-preoperative plan) were 1.7° (standard deviation (SD) 2.0) (inclination) and 2.5° (SD 2.1°) (anteversion) in DDH patients, and no significant differences were found between non-DDH and DDH patients. The mean absolute differences for 3D cup position were 1.1 mm (SD 1.0) (coronal plane) and 1.2 mm (SD 2.1) (axial plane) in DDH patients, and no significant differences were found between two groups. No significant difference was found either in cup alignment between postoperative CT and navigation record after cup screws or in the severity of DDH. Excellent restoration of leg length and combined offset were achieved in both groups.ConclusionWe demonstrated that robotic-assisted THA may achieve precise cup positioning in DDH patients, and may be useful in those with severe DDH.Cite this article: Bone Joint Res 2021;10(10):629–638.

Residual Acetabular Dysplasia in the Reduced Hip.

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). 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. 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 Association of Asymmetric Skinfolds and the Diagnosis of Developmental Dysplasia of the Hip in Infants.

The clinical finding of asymmetric skinfolds (ASF) in infants is used to indicate the possibility of developmental dysplasia of the hip (DDH). The association of ASF and a diagnosis of DDH remains unknown. To determine the association of ASF in the gluteal and femoral regions with a diagnosis of DDH. The correlation of ASF and other physical examination findings with DDH was compared retrospectively. The medical records of infants who underwent DDH screening in the clinic were analyzed. The physical examination findings were reviewed and categorized as ASF, clunk of the hip, limb-length discrepancy, hip abduction limitation, combined conditions of musculoskeletal disorders, and regular screening for DDH. The hip conditions were classified by Graf's ultrasound method. Type IIb and higher classifications were defined as DDH. The diagnosed rate and severity of DDH based on physical examination findings were calculated and compared. Clinical data of 3266 infants aged up to 6 months were reviewed, and 194 infants were diagnosed with DDH by ultrasound examination. ASF was the most common indication for DDH screening (64.5%; 2107/3266). However, this was poorly correlated with a diagnosis of DDH (4.79%; P < .0001). No difference was found between the Graf classification severity and various indications ( P = .079). Clinicians should recognize that, although ASF is the most common reason for DDH screening in infants, ASF does not correlate with a diagnosis of DDH. Additional research should examine the relationship between DDH and ASF in other populations.

The Three-Dimensional Morphology of Femoral Medullary Cavity in the Developmental Dysplasia of the Hip.

ObjectiveThis study aimed to assess the morphology of the femoral medullary canal in subjects with developmental dysplasia of the hip (DDH) with the intent of improving the design of femoral stems in total hip arthroplasty.MethodsComputed tomography images of 56 DDH hips, which were classified into Crowe I to Crowe IV, and 30 normal hips were collected and used to reconstruct three-dimensional morphology of the femoral medullary cavity. Images of twenty-one cross sections were taken from 20 mm above the apex of the lesser trochanter to the isthmus. The morphology of femoral cavity was evaluated on each cross section for the longest canal diameter, the femoral medullary torsion angle (FMTA), and the femoral medullary roundness index (FMRI).ResultsThe Crowe IV group displayed the narrowest medullary canal in the region superior to the end of the lesser trochanter, but then gradually aligned with the medullary diameter of the other groups down to the isthmus. The FMTA along the femoral cavity increased with the severity of DDH, but the rate of variation of FMTA along the femoral canal was consistent in the DDH groups. The DDH hips generally showed a larger FMRI than the normal hips, indicating more elliptical shapes.ConclusionA femoral stem with a cone shape in the proximal femur and a cylindrical shape for the remainder down to the isthmus may benefit the subjects with severe DDH. This design could protect bone, recover excessive femoral anteversion and facilitate the implantation in the narrow medullary canal.

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

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.

Prognostic value of severity of dislocation in late-detected developmental dysplasia of the hip.

PurposeThe aims of this study were to evaluate the reliability of three classifications of severity of dislocation in late-detected developmental dysplasia of the hip (DDH), especially to assess whether they are predictive of long-term outcomes.MethodsTwo groups of patients were analyzed. Group 1 (57 patients, 69 hips) underwent closed reduction between 1958 and 1962. Mean age at reduction was 20.3 months (4 to 65). Group 2 (50 patients, 54 hips) treated between 1996 and 2005, was used for analysis of the association between severity of dislocation and treatment (open or closed reduction). The primary radiographs were graded according to the Tönnis classification, the classification of the International Hip Dysplasia Institute and a new method based on the position of the most lateral point of the proximal femoral metaphysis (lateral metaphysis height classification, LMH). The outcome at a mean age of 51.2 years (55 to 60) was graded according to the occurrence of osteoarthritis (OA) and total hip arthroplasty (THA).ResultsThere were significant associations between the classifications, and the intra- and interobserver agreements were high. More severe grades of DDH were significantly associated with age ≥ 18 months and with open reduction. None of the classifications were significantly associated with long-term OA. The LMH method was significantly associated with the need for THA, whereas the other classifications were not.ConclusionAll the classifications were reliable in grading severity of DDH. The LMH method seems preferable in clinical practice because the main landmarks were easy to define and because it had long-term prognostic value.Level of EvidenceIII

First Description of Factors Influencing the Outcome of Developmental Dysplasia of the Hip in Children’s Medical Center

Background: There are several factors may have an impact on the prognosis of developmental dysplasia of the hip (DDH). They may change the outcome and treatment if they are present in a patient. Objectives: The objective of this study is to determine the association of those factors with the outcome. Patients and Methods: The study was performed on 74 infants with DDH in Children’s Medical Centre. After obtaining informed consent and ethical approval, patients with DDH confirmed by ultrasound were included, and possible risk factors including severity of DDH based on the Graf criteria, follow-up length, age, gender, laterality, type of delivery, amniotic fluid index, fetal anomalies, birth order of children, and methods of treatment were collected and compared against treatment response. Results: There were 58 female and 19 male patients with a mean age of 6.54 weeks. Bilateral DDH was found in 31 females and nine males. The average alpha and beta angles were 53.19 ± 5.7 and 66.53 ± 6.6 degree, respectively. The severity of DDH had a significant association with treatment response (P = 0.003). Recovery was better in females than in males (P = 0.031). In addition, the first‐born infants had a better response (P = 0.001). A meaningful connection (P = 0.01) was noted between the amniotic fluid index as well as renal/limb anomalies and treatment response. Type of delivery (cesarean versus vaginal) or fetal presentation had no significant association with treatment response (P &gt; 0.05). Conclusion: Factors with a negative impact on DDH outcomes include the severity of DDH, male gender, higher birth order, oligohydramnios, renal and limb anomalies.

Relations between the Crowe classification and the 3D femoral head displacement in patients with developmental dysplasia of the hip

BackgroundThe purpose of this study was to investigate the relationship between the three dimensional (3D) femoral head displacement in patients with developmental dysplasia of the hip (DDH) and Crowe classification.MethodsRetrospectively, CT scans of 60 DDH patients and 55 healthy demography-matched healthy control subjects were analyzed. Using the anterior pelvic plane a pelvic anatomic coordinate system was established. The center coordinates of the femoral heads of both the DDH patients and control subjects were quantified relative to the pelvic coordinate system and were mapped proportionally to a representative normal pelvis for comparison.ResultsIn the anteroposterior (AP) direction, the center of the femoral head was significantly more anterior in the DDH patients (type I, II, and III, respectively45.0 ± 5.5, 42.9 ± 7.1, and 43.9 ± 4.6 mm) when compared to the controls (50.0 ± 5.2 mm) (p < 0.001 for all). In the medial-lateral (ML) direction, the center of the femoral head was significantly more lateral in the DDH patients (type I, II, and III =103.5 ± 8.6, 101.5 ± 6.6, 102.1 ± 11.2 mm) when compared to the controls (87.5 ± 5.1 mm) (p < 0.001 for all). In the superior-inferior (SI) direction, the center of the femoral head was significantly more proximal in the DDH patients (type I, II, and III =62.4 ± 7.3, 50.0 ± 6.3, and 43.2 ± 6.6 mm) when compared to the controls (66.0 ± 6.2 mm) (p < 0.001 for all).ConclusionsThe severity of DDH using the Crowe classification was related to the degree of the femoral head displacement in the SI direction, but not in the ML or AP directions. By assessing the 3D femoral head displacement in DDH patients, individualized component positioning might benefit surgical outcome.

Genetic Predisposition to Developmental Dysplasia of the Hip

BackgroundThe etiopathogenesis of developmental dysplasia of the hip (DDH) has not been clarified. This systematic review evaluated current literature concerning all known chromosomes, loci, genes, and their polymorphisms that have been associated or not with the prevalence and severity of DDH. MethodsFollowing the established methodology of Meta-analysis of Observational Studies in Epidemiology guidelines, MEDLINE, EMBASE, and Cochrane Register of Controlled Trials were systematically searched from inception to January 2019. ResultsForty-five studies were finally included. The majority of genetic studies were candidate gene association studies assessing Chinese populations with moderate methodological quality. Among the most frequently studied are the first, third, 12th,17th, and 20th chromosomes. No gene was firmly associated with DDH phenotype. Studies from different populations often report conflicting results on the same single-nucleotide polymorphism (SNP). The SNP rs143384 of GDF5 gene on chromosome 20 demonstrated the most robust relationship with DDH phenotype in association studies. The highest odds of coinheritance in linkage studies have been reported for regions of chromosome 3 and 13. Five SNPs have been associated with the severity of DDH. Animal model studies validating previous human findings provided suggestive evidence of an inducing role of mutations of the GDF5, CX3CR1, and TENM3 genes in DDH etiopathogenesis. ConclusionDDH is a complex disorder with environmental and genetic causes. However, no firm correlation between genotype and DDH phenotype currently exists. Systematic genome evaluation in studies with larger sample size, better methodological quality, and assessment of DDH patients is necessary to clarify the DDH heredity. The role of next-generation sequencing techniques is promising.

Genetic association study of common variants in TGFB1 and IL-6 with developmental dysplasia of the hip in Han Chinese population

Developmental dysplasia of the hip (DDH) is a congenital or developmental deformation or misalignment of the hip joint that is affected by environmental and genetic factors. Recently, polymorphisms in both TGFB1 and IL-6 have been identified as being significantly associated with hip osteoarthritis in Caucasians. In this study, we conducted a case-control study involving 4,206 Han Chinese individuals to investigate the effects of TGFB1 and IL-6 on the disease status and severity of DDH. A total of 32 single-nucleotide polymorphisms (SNPs) were selected to ensure coverage of the two genetic loci. We found SNP rs1800470 in TGFB1 (OR = 1.255, P = 0.0004) and rs1800796 (OR = 0.84, P = 0.0228) in IL-6 to be significantly associated with DDH in this cohort. Further haplotype-based analysis replicated this significant result. Another SNP in IL-6, rs1800796, showed a marginally significant association with DDH. As a non-synonymous SNP, rs1800470 alters the amino acid sequence of the polypeptide encoded by TGFB1; however, bioinformatics analyses revealed that this SNP has limited functional significance. No significant results were obtained in an association study focusing on the severity of DDH and epistasis analysis. Our findings support an important role for TGFB1 in the risk of DDH. Further research is needed to validate the weak association between rs1800796 in IL-6 and DDH.

Serum prolidase activity and oxidative–antioxidative status in patients with developmental dysplasia of the hip and its relationship with radiographic severity

Background: We aimed to investigate serum prolidase activity and to investigate its association with oxidative–antioxidative status in patients with developmental dysplasia of the hip (DDH).Methods: Oxidative status parameters, including lipid hydroperoxide (LOOH), total oxidant status (TOS), and the oxidative stress index (OSI), and antioxidative status parameters, free sulfhydryl groups (Total –SH), and total antioxidative capacity (TAC), as well as serum prolidase activity were assessed in patients with DDH (n = 93), and in healthy controls (n = 82). The severity of dysplasia was evaluated according to the Tonnis grading system.Results: Serum prolidase activity and the oxidant parameters (LOOH, TOS, and OSI) were significantly higher and the antioxidant parameters (Total –SH and TAC) were significantly lower in patients with DDH compared to the controls (P < 0.005 for all). Serum prolidase activity was positively correlated with the Tonnis grade of DDH and LOOH, TOS, and OSI levels (P < 0.001 for all), but inversely correlated with total –SH and TAC levels (P < 0.001 for all).Conclusion: Increased levels of serum prolidase activity, LOOH, TOS, and OSI, and decreased levels of total –SH and TAC, may be associated with DDH, and these parameters may be useful adjunctive tools to assess the severity of DDH.

A New Radiographic Classification System for Developmental Hip Dysplasia is Reliable and Predictive of Successful Closed Reduction and Late Pelvic Osteotomy.

The Tonnis radiographic classification of developmental dysplasia of the hip (DDH) has been used as a prognostic indicator for patients with walking-age DDH. The International Hip Dysplasia Institute (IHDI) classification, a new radiographic classification system, has been proposed to be more reliable by its creators. We sought to validate its reliability using independent observers, to compare it to the Tonnis method, and to assess its prognostic significance in a large cohort of patients. A consecutive series of walking-age DDH patients were examined radiographically and classified by the Tonnis and IHDI schemes by 3 independent observers. Interobserver agreement was determined using the Kappa method. Clinical data were collected on patients with regard to success of closed reduction, need for later pelvic osteotomy, and presence of subsequent radiographic avascular necrosis (AVN). The prognostic value of the Tonnis and IHDI classifications to predict these clinical outcomes was determined. A total of 287 hips were available for analysis of the classification schemes. In total, 235 hips underwent attempted closed reduction and were eligible for analysis of successful closed reduction, and 131 hips had >4-year follow-up and were utilized for analysis of late pelvic osteotomy and AVN. Both classifications showed excellent interobserver reliability and in general, there was nonstatistically significant better reliability for the IHDI versus the Tonnis classification. In multivariate analysis, both IHDI and Tonnis classifications were found to be predictive of successful closed reduction and need for late pelvic osteotomy. Both methods showed trends toward being predictive of AVN rate, without statistical significance. The IHDI classification is subjectively more facile to use and has excellent interrelater agreement for classifying the radiographic severity of DDH. It is also reliable in predicting success of closed reduction and need for late pelvic osteotomy. practitioners and researchers should consider the IHDI classification as a useful classification scheme and prognosticator when considering treatment options for late-presenting DDH. Practitioners and researchers should consider the IHDI classification as a useful classification scheme and prognosticator when considering treatment options for late-presenting DDH. Level III.

Reliability of a New Radiographic Classification for Developmental Dysplasia of the Hip.

Background:Existing radiographic classification schemes (eg, Tönnis criteria) for DDH quantify the severity of disease based on the position of the ossific nucleus relative to Hilgenreiner’s and Perkin’s lines. By definition, this method requires the presence of an ossification centre, which can be delayed in appearance and eccentric in location within the femoral head. A new radiographic classification system has been developed by the International Hip Dysplasia Institute (IHDI), which uses the mid-point of the proximal femoral metaphysis as a reference landmark, and can therefore be applied to children of all ages. The purpose of this study was to compare the reliability of this new method with that of Tönnis, as the first step in establishing its validity and clinical utility.Methods:Twenty standardized anteroposterior pelvic radiographs of children with untreated DDH were selected purposefully to capture the spectrum of age (range, 3 to 32 mo) at presentation and disease severity. Each of the hips was classified separately by the IHDI and Tönnis methods by 6 experienced pediatric orthopaedists from the United States, Canada, Mexico, United Kingdom, and by 2 orthopaedic senior residents. The inter-rater reliability was tested using the Intra Class Correlation coefficient (ICC) to measure concordance between raters.Results:All 40 hips were classifiable by the IHDI method by all raters. Ten of the 40 hips could not be classified by the Tönnis method because of the absence of the ossific nucleus on one or both sides. The ICC (95% confidence interval) for the IHDI method for all raters was 0.90 (0.83-0.95) and 0.95 (0.91-0.98) for the right and left hips, respectively. The corresponding ICCs for the Tönnis method were 0.63 (0.46-0.80) and 0.60 (0.43-0.78), respectively. There was no significant difference between the ICCs of the 6 experts and 2 trainees.Conclusions:The IHDI method of classification has excellent inter-rater reliability, both among experts and novices, and is more widely applicable than the Tönnis method as it can be applied even when the ossification centre is absent.Level of Evidence:Level II (diagnostic).

Effect of periacetabular osteotomy for acetabular dysplasia clarified by three-dimensional finite element analysis

BackgroundFinite element analysis (FEA) has been applied for the biomechanical analysis of acetabular dysplasia, but not for biomechanical studies of periacetabular osteotomy (PAO) or those performing analysis taking into consideration the severity of acetabular dysplasia. This study aimed to perform biomechanical evaluation of changes in stress distribution following PAO and to determine the effect of the severity of developmental dysplasia of the hip (DDH) using three-dimensional FEA. MethodsA normal model was designed with a 25° center-edge (CE) angle and a 25° vertical-center-anterior margin (VCA) angle. DDH models were designed with CE and VCA angles each of 10, 0, or −10°. Post-PAO models were created by separating each DDH model and rotating the acetabular bone fragment in the anterolateral direction so that the femoral head was covered by the acetabular bone fragment, with CE and VCA angles each at 25°. ResultsCompared to the normal hip joint model, the DDH models showed stress concentration in the acetabular edge and contacting femoral head, and higher stress values; stress increased with decreasing CE and VCA angles. Compared to the DDH models, the post-PAO models showed near-normal patterns of stress distribution in the acetabulum and femoral head, with stress concentration areas shifted from the lateral to medial sides. Stress dispersion was especially apparent in the severe acetabular dysplasia models. PAO provided greater decreases in the maximum values of von Mises stress in the load-bearing area of the acetabulum and femoral head when applied to the DDH models of higher degrees of severity, although the values increased with increasing severity of DDH. ConclusionsPAO is expected to provide biomechanical improvement of the hip joint and to be particularly effective in patients with severe preoperative DDH, although the results also suggested a limitation in the applicability of PAO for these patients.