Measurement Of Acetabular Index Research Articles

Association Between Alpha Angle and Acetabular Index in Screening for Developmental Dysplasia of the Hip.

Developmental dysplasia of the hip (DDH) is a critical orthopedic condition ranging from minor hip joint instability to complete dislocations, demanding early intervention to avoid severe complications, especially in children. In Mexico, stringent regulations under the Norma Oficial Mexicana (NOM) mandate hip screening for pediatric patients. The primary objective of this study is to investigate the relationship between alpha angles and the acetabular index in patients at six months of age, aiming to determine whether an increase in the alpha angle correlates with a better acetabular index. We included 120 patients who were screened for hip issues with Graf's methodology in June 2023 and September 2023 at the General Hospital of Mexico "Dr. Eduardo Liceaga" in Mexico City before three months of age and attended their follow-up appointment at six months of age, where acetabular index measurement was performed using the Carestream platform on institutional X-rays. In our statistical analysis, we obtained a statistically significant relationship between an increase in the left hip alpha angle and a decrease in the left hip acetabular index (p=0.015)although it was not significant for an acetabular index of less than 25° (p=0.055). A significant relationship was observed between the right hip acetabular index and the right hip alpha angle (p=0.017) but not significant for an acetabular index less than 25° (p=0.10). Universal hip screening is crucial for the early detection of DDH. Our study emphasizes using alpha-angle measurements (>70°) as reliable indicators of normal hip health.

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

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

Diagnosis and Treatment Planning of Developmental Hip Dysplasia: Evaluation of Care Practices of the Members of the Turkish Pediatric Orthopedics Association.

Developmental dysplasia of the hip is one of the most important causes of childhood disabilities. Although there are accepted treatment algorithms for developmental dysplasia of the hip, diagnosis and treatment approaches can show variations in the management among physicians. This study aimed to develop a diagnosis and treatment algorithm for developmental dysplasia of the hip according to the preferences of members of the Turkish Pediatric Orthopedics Association. An interview by telephone call was made with 76 orthopedists (group 1: more experienced 39 physicians, group 2: less experienced 37 physicians) who are members of the Turkish Pediatric Orthopedics Association. Participants were q uesti onnai red ab out their demographic information, experiences, diagnostic criteria that they use for developmental dysplasia of the hip, and treatment approaches to patient scenarios of different ages. Most of the participants recommended universal screening at the age of 4 weeks. It was observed that the most significant physical examination finding was limited hip abduction, and the most frequently used radiographic evaluation on x-ray was acetabular index measurement. The most frequently used description for dysplasia was found as acetabular index >30°. Although there are some differences among orthopedists in the diagnosis, treatment, and follow-up approach of developmental dysplasia of the hip, there was no significant difference according to the experience-based grouping. The treatment algorithm, which was created with the most frequently given answers, was designed, which we think may be beneficial for pediatricians and orthopedists.

Application of deep-learning-based artificial intelligence in acetabular index measurement.

To construct an artificial intelligence system to measure acetabular index and evaluate its accuracy in clinical application. A total of 10,219 standard anteroposterior pelvic radiographs were collected retrospectively from April 2014 to December 2018 in our hospital. Of these, 9,219 radiographs were randomly selected to train and verify the system. The remaining 1,000 radiographs were used to compare the system's and the clinicians' measurement results. All plain pelvic films were labeled by an expert committee through PACS system based on a uniform standard to measure acetabular index. Subsequently, eight other clinicians independently measured the acetabular index from 200 randomly selected radiographs from the test radiographs. Bland-Altman test was used for consistency analysis between the system and clinician measurements. The test set included 1,000 cases (2,000 hips). Compared with the expert committee measurement, the 95% limits of agreement (95% LOA) of the system was -4.02° to 3.45° (bias = -0.27°, P < 0.05). The acetabular index measured by the system within all age groups, including normal and abnormal groups, also showed good credibility according to the Bland-Altman principle. Comparison of the measurement evaluations by the system and eight clinicians vs. that of, the expert committee, the 95% LOA of the clinician with the smallest measurement error was -2.76° to 2.56° (bias = -0.10°, P = 0.126). The 95% LOA of the system was -0.93° to 2.86° (bias = -0.03°, P = 0.647). The 95% LOA of the clinician with the largest measurement error was -3.41° to 4.25° (bias = 0.42°, P < 0.05). The measurement error of the system was only greater than that of a senior clinician. The newly constructed artificial intelligence system could quickly and accurately measure the acetabular index of standard anteroposterior pelvic radiographs. There is good data consistency between the system in measuring standard anteroposterior pelvic radiographs. The accuracy of the system is closer to that of senior clinicians.

Splinting for the non-operative management of developmental dysplasia of the hip (DDH) in children under six months of age.

Splinting for the non-operative management of developmental dysplasia of the hip (DDH) in children under six months of age.

Radiological Outcome in Developmental Dysplasia of the Hip Following Varus Derotation Osteotomy: A Case Series

Introduction&#x0D; Developmental dysplasia of the hip (DDH) includes femoral head subluxation or dislocation and/or acetabular dysplasia. The gold standard treatment for DDH during walking age remains controversial. Treatment modalities that have been proposed to treat DDH after walking age are femoral osteotomy and pelvic osteotomy. The aim of this study was to assess the radiographic results of surgical treatment of DDH after the walking age.&#x0D; Case Presentation&#x0D; Four patients were included in this study. All patients presented with DDH in walking age and underwent varus derotational osteotomy (VDRO). Measurements of acetabular index (AI) and migration percentage (MP) was done on pelvic x-ray before and after the procedure to assess the outcome.&#x0D; Conclusion&#x0D; This study showed satisfactory outcomes following femoral osteotomy in ambulatory DDH in terms of migration index and AI. Further study with more samples is needed for higher level of certainty.

Children treated for developmental dysplasia of the hip at birth and with normal acetabular index at 1 year: How many had residual dysplasia at 5 years?

Purpose:The purpose of the study was to assess the effect of further follow-up for children treated for developmental dysplasia of the hip, with normal clinical and radiological findings at 1-year time point. The effect was quantified by the number of hips with a pathologic deterioration up to 5 years.Methods:Among 47,289 children born in Sør-Trøndelag county in Norway between 2003 and 2015, 265 children had developmental dysplasia of the hip. Of these, 164 children (239 hips) treated for developmental dysplasia of the hip with normal clinical findings and normal acetabular index at the 1-year time point were included in the study. The number of hips with pathologic acetabular index at the 5-year time point were reported. The diagnostic uncertainty related to radiological measurements was quantified together with the effect of introducing a second radiographic measurement, the center edge angle.Results:A total of 239 treated hips were normal at the 1-year time point. At 5-year time point, 10 (4.2%) hips had a pathologic acetabular index measurement and none classified to have developmental dysplasia of the hip caused by measurement inaccuracy. Eight (3.3%) hips had pathologic center edge angle measurement. Four hips had both pathologic acetabular index and center edge angle measurements, with three later treated with surgery. The intra- and interobserver repeatability coefficients were within 3.1°–6.6°.Conclusion:The repeatability coefficient of the acetabular index measurements was high and no hips could be classified to have developmental dysplasia of the hip at the 5-year time point when taking this repeatability into account. Hips classified as pathologic combining acetabular index and center edge angle measurements were likely to be treated with surgery for residual dysplasia. We recommend further follow-up for these children.Level of evidence:level II.

Reliability of acetabular index measurement in developmental dysplasia of the hip screening by orthopaedic trainees: a comparative study

Background: Radiographic measurements are used for screening of developmental dysplasia of the hip (DDH) in children. The ability to detect acetabular dysplasia requires validated radiographic outcome measures. The acetabular index (AI) measurement has been shown to be a reliable measure worldwide. This study aims to test the reliability of the AI measurement in a DDH screening population by orthopedic junior and senior residents. Methods: The review examined 470 radiographs taken during 4 yr (2016-2019) in a university hospital. AI measurement was performed by two surgeons, four senior residents, and four junior residents at three different times. The intra- and interobserver reliability for each group was assessed. Results: The intraobserver reliability intraclass correlation coefficient (ICC) for the AI measurement performed by seniors was excellent at 0.98 [confidence interval (CI) 0.98 to 0.99] for the right side and 0.99 (CI 0.98 to 0.99) for left side. Indistinguishably, the ICC for AI measurement performed by orthopaedic juniors for right and left side was excellent at 0.96 (CI 0.95 to 0.97) and 0.95 (CI 0.95 to 0.96), respectively. The overall ICCs for interobserver reliability for the AI measurement between professors, seniors and juniors for right and left side was between good and excellent at 0.89 (CI 0.87 to 0.90) and 0.89 (CI 0.87 to 0.91), respectively. Conclusions: Orthopaedic juniors are less reliable in terms of intra- and interobserver variability in detecting DDH in screening program in comparison with seniors using AI measurement in a pediatric orthopaedic clinic. Level of Evidence: Level III.

Is capsulorrhaphy a necessary step during open reduction of developmental dysplasia of the hip? A randomized controlled trial.

To investigate the necessity of performing capsulorrhaphy during open reduction of DDH. A single-centre, prospective,randomized controlled trial was conducted between 2015 and 2020. The study included 82 hips in 67 patients with developmental dysplasia of the hip (DDH) who were treated with open reduction via the anterior approach. Patients were randomized into two equal groups (41 hips in each group); group A (capsulorrhaphy was done) and group B (capsulorrhaphy was not done). Dega osteotomy was performed in all cases, while femoral derotation shortening osteotomy was performed only in four hips in group A and four hips in group B. The mean age at the time of surgery was 33 ± 22.3months. The follow-up period was 24months for all patients. At the final follow-up, maintenance of reduction was chosen as the primary outcome and was assessed radiologically by the Severin's grading system. Secondary outcome measures were functional evaluation (by using the modified McKay's criteria), Shenton line assessment, acetabular index measurement, and complications. According to the Severin's grading system, concentric reduction was achieved in 36 hips in group A and 37 hips in group B, subluxation occurred in three hips in each group, and redislocation was encountered in two hips in group A and one hip in group B. There was no statistically significant difference between both groups (p-value = 0.239). According to the modified McKay's criteria, the results were satisfactory (excellent and good) in 34 hips (82.9%) in group A and 36 hips (87.8%) in group B. The difference was statistically insignificant (p-value = 0.352). The rate of complications was higher in group A (17.1%) than group B (12.2%) (p-value = 0.532). The stability of the hip joint after open reduction depends mainly on adequate removal of soft tissue obstacles that impede reduction and proper correction of the bony configuration of the hip using pelvic and/or femoral osteotomy. So, the authors believe that capsulorrhaphy is not necessary in the surgical management of DDH, provided that adequate soft tissue and bony gestures are combined.

Clinical application of artificial intelligence-assisted diagnosis using anteroposterior pelvic radiographs in children with developmental dysplasia of the hip.

The diagnosis of developmental dysplasia of the hip (DDH) is challenging owing to extensive variation in paediatric pelvic anatomy. Artificial intelligence (AI) may represent an effective diagnostic tool for DDH. Here, we aimed to develop an anteroposterior pelvic radiograph deep learning system for diagnosing DDH in children and analyze the feasibility of its application. In total, 10,219 anteroposterior pelvic radiographs were retrospectively collected from April 2014 to December 2018. Clinicians labelled each radiograph using a uniform standard method. Radiographs were grouped according to age and into 'dislocation' (dislocation and subluxation) and 'non-dislocation' (normal cases and those with dysplasia of the acetabulum) groups based on clinical diagnosis. The deep learning system was trained and optimized using 9,081 radiographs; 1,138 test radiographs were then used to compare the diagnoses made by deep learning system and clinicians. The accuracy of the deep learning system was determined using a receiver operating characteristic curve, and the consistency of acetabular index measurements was evaluated using Bland-Altman plots. In all, 1,138 patients (242 males; 896 females; mean age 1.5 years (SD 1.79; 0 to 10) were included in this study. The area under the receiver operating characteristic curve, sensitivity, and specificity of the deep learning system for diagnosing hip dislocation were 0.975, 276/289 (95.5%), and 1,978/1,987 (99.5%), respectively. Compared with clinical diagnoses, the Bland-Altman 95% limits of agreement for acetabular index, as determined by the deep learning system from the radiographs of non-dislocated and dislocated hips, were -3.27° - 2.94° and -7.36° - 5.36°, respectively (p < 0.001). The deep learning system was highly consistent, more convenient, and more effective for diagnosing DDH compared with clinician-led diagnoses. Deep learning systems should be considered for analysis of anteroposterior pelvic radiographs when diagnosing DDH. The deep learning system will improve the current artificially complicated screening referral process. Cite this article: Bone Joint J 2020;102-B(11):1574-1581.

Innominate Salter osteotomy using resorbable screws: a retrospective case series and presentation of a new concept for fixation.

PurposeThe Salter innominate osteotomy (SIO) in children is traditionally stabilized by Kirschner-wires, which have issues regarding stability, infection and the need to be extracted. To counter these disadvantages, we present a surgical method to stabilize SIO with modern resorbable poly lactic-co-glycolic acid screws. Using a case series of 21 patients treated with SIO for developmental dysplasia of the hip or Legg-Calvé-Perthes disease we evaluate the feasibility of the method.MethodsThe integrity of the osteotomy was interpreted by radiological measurements of acetabular index, centre-edge angle and Reimer’s index. Perioperative and postoperative complications were evaluated.ResultsRadiographic evaluation revealed a stable osteotomy and favourable development in all measured parameters with the exception of one patient who fell out of bed the first day postoperatively. No other perioperative surgical complications were observed and there were no local reactions to the resorbable screws.ConclusionModern resorbable screws carry multiple benefits both for the patient and the surgeon. In our case series the implants provided sufficient stability and the implants caused no local reactions. The use of resorbable implants gave the surgeon a wider range of possible screw placements and avoided the need for implant removal.Level of evidenceLevel IV – Case series

Reliability of the sourcil method of acetabular index measurement in developmental dysplasia of the hip.

PurposeThe ability to monitor and study developmental dysplasia of the hip (DDH) requires validated radiographic outcome measures. The sourcil method of acetabular index measurement (AI-S) has not yet been shown to be a reliable measure of acetabular dysplasia in a DDH population, despite its widespread use. The aims of this study were to test the reliability of the AI-S method in a DDH population, and to compare the reliability of the AI-S method with that of the classic lateral edge method (AI-L).MethodsFrom an institutional database, standardized anteroposterior hip radiographs were obtained from a cohort of 35 female patients (70 hips) at two and five years of age who had been treated nonoperatively for DDH. Three observers independently measured the acetabular index using the AI-L and AI-S methods on all 70 hips at two time points, four weeks apart.ResultsThe inter-rater reliability intraclass correlation coefficient (ICC) for the AI-L and AI-S methods was between good and excellent at 0.94 (confidence interval (CI) 0.89 to 0.96) and 0.91 (CI 0.87 to 0.94), respectively. The ICCs for intra-rater reliability for the AI-L method were excellent at 0.93 (CI 0.90 to 0.95), 0.95 (CI 0.93 to 0.97) and 0.95 (CI 0.94 to 0.97) for raters 1, 2 and 3, respectively. The ICCs for intra-rater reliability for the AI-S method were between good and excellent at 0.91 (CI 0.87 to 0.93), 0.93 (CI 0.90 to 0.95) and 0.90 (CI 0.86 to 0.93) for raters 1, 2 and 3 respectively.ConclusionBoth AI-S and AI-L methods are equally reliable radiographic measures of DDH.Level of EvidenceLevel III (diagnostic)

The influence of acetabular morphology on prediction of proximal femur fractures types in an elderly population.

The role of proximal femur morphology to the development of certain proximal femur fracture types both femoral neck and trochanteric fractures has been observed. However, the relavance of acetabular morphology to the development of proximal femur fractures is not extensively questioned. Therefore the aim of the study was to determine whether there is a correlation between acetabular morphology and pathogenesis of 2 different hip fracture types after low energy trauma. This retrospective study includes 60 cases (41 women, 19 men) with a proximal femoral fracture after a low energy trauma between July 2012 and December 2014. Acetabular depth and acetabular index were measured on pelvic radiographs. Neck shaft angle, hip axis length and cortical index were measured on pelvic computed tomography scans. All measurements were performed on the contralateral hip. Mean age was 77.56 ± 8.99 years (range 61-92 years). No statistically significant difference was found with regard to neck shaft angle, acetabular depth or cortical index measurements between patients with femoral neck fracture and patients with trochanteric femoral fractures (p>0.05). Acetabular index measurement was higher (p = 0.001) and hip axis length measurement was lower (p = 0.001) in trochanteric fracture group as compared to femoral neck fracture. The rate of trochanteric femur fractures is higher in patients with high acetabular index, whereas the rate of femoral neck fractures is higher in patients with increased hip axis length.

Functional status and amount of hip displacement independently affect acetabular dysplasia in cerebral palsy.

Acetabular dysplasia is the one of main causes of hip displacement in patients with cerebral palsy (CP). Although several studies have shown a relationship between hip displacement and acetabular dysplasia, relatively few have evaluated the association between quantitative acetabular dysplasia and related factors, such as Gross Motor Function Classification System (GMFCS) level. We performed a morphometric analysis of the acetabulum in patients with CP using multiplanar reformation of computed tomography data. The three directional acetabular indices (anterosuperior, superolateral, and posterosuperior) were used to evaluate acetabular dysplasia. Consequently, linear mixed-effects models were used to adjust for related factors such as age, sex, GMFCS level, and migration percentage. A total of 176 patients (mean age 9y 5mo, range 2y 4mo-19y 6mo; 104 males, 72 females) with CP and 55 typically developing individuals (mean age 13y 6mo, range 2y 5mo-19y 10mo; 37 males, 18 females) in a comparison group were enrolled in this study. Statistical modelling showed that all three directional acetabular indices independently increased with GMFCS level (p<0.001) and migration percentage (p<0.001). Acetabular dysplasia was independently affected by both the amount of hip displacement and the GMFCS level. Thus, physicians should consider not only the migration percentage but also three-dimensional evaluation in patients at high GMFCS levels.

Natural history of hip instability in infants (without subluxation or dislocation): a three year follow-up.

BackgroundThe natural history of hip instability (without subluxation or dislocation) and treatment in infants remain controversial. We performed a retrospective cohort case-only study with blinded, prospectively collected data to assess normalization of the acetabular index in consecutive untreated infant hips with sonography instability.MethodsConsecutive hips meeting inclusion criteria were followed by sonography/radiography and data analyzed using tabular and regression models.ResultsIn 48 hips, acetabular index measured by radiography normalized within 3 years of age without treatment. Normalization by age occurred: 7 months in 35%, 12 months in 67%, 18 months in 75%, 24 months in 81%, and 36 months in 100%. Two patterns of normalization of the acetabular index were observed: group I showed ossification in a physiological range of normal by 7 months of age, and group II had delayed ossification with later normalization of the acetabular index measurement. Breech presentation (p =0.013) and cesarean delivery (p =0.004) statistically directly correlated with a later normalization.ConclusionsThe natural history of infant hip instability (without subluxation or dislocation), which is reduced at rest and unstable with stress as diagnosed by the Harcke method of sonography, has spontaneous normalization of the acetabular index within 3 years of age. We suggest three patterns of acetabular ossification in unstable infants’ hips: (I) normal ossification, (II) delayed ossification with normalization of the acetabular index by age 3 years, and (III) defective secondary centers of ossification with an upward tilt of the lateral acetabular rim in adolescence.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-355) contains supplementary material, which is available to authorized users.

Arthroscopic-assisted surgical treatment for developmental dislocation of the hip before the age of 18 months

The purpose of this study is to evaluate the results of arthroscopy assisted surgical treatment of developmental dislocation of the hip (DDH). Arthroscopic assisted surgical treatment was performed on nine hips of nine female children with DDH using our method, published previously, between January 2001 and December 2005. Their ages ranged from 9 to 16months. Percutaneous adductor tenotomies were performed in seven cases. A spica cast and abduction splint were used for 11-17weeks postoperatively. Acetabular index and Shenton line were used for preoperative and postoperative radiologic evaluation. Also, the cases were evaluated postoperatively with respect to range of motion restriction, and the leg length discrepancy. The average follow-up was 47.7months (range 22-79months). Acetabular index measurements of cases in the preoperative/postoperative periods were as follows: preoperative mean angle 39.9° (range 34°-52°)/postoperative mean angle 26° (range 22°-34°). Hip joint restriction and leg length discrepancy were not observed postoperatively. However, two patients had acetabular dysplasia. Acetabular dysplasia was completely resolved in one patient in the third year of follow-up, whereas Salter innominate osteotomy, required in another patient, was in the second year of follow-up. The latter patient was the oldest case (16-month-old) in our series. Based on the results of this study, treatment of developmental hip dysplasia with arthroscopic-assisted surgical treatment technique may be safe and effective method. Further clinical studies will be required to confirm this study.

Variabilidad en la medición del índice acetabular

Developmental dysplasia of the hip (DDH) is a spectrum of diseases ranging from frank dislocation of the hip to mild acetabular dysplasia. DDH screening for detection is performed routinely in our country using pelvic x-ray at 3 months of age. The radiographic measured acetabular index is used to evaluate the dysplastic hip, at initial presentation and during follow-up. Objective: Evaluation of the intra- and inter-observer variability, among medical professionals, when measuring acetabular index. Methods: Four reviewers (a children orthopedic surgeon, a general practitioner, a pediatrician and a radiologist) performed acetabular index measurement in 100 radiographs (200 hips), on three occasions, separated each by one month (600 total measurements). An independent observer evaluated the measurement reproducibility. The intra-class correlation coefficient to determine significant differences was used. Results: The intra-observer variability was less than the inter-observer variability. The intra-observer variability was similar among the different assessors, ± 1.5 degrees. The inter-observer variability was ± 3.4 degrees. Conclusions: A high concordance among measurements was reported, evidencing a high reproducibility of the acetabular index; this index is a reliable method for the diagnosis and follow-up of acetabular dysplasia.

Pelvic Rotation and Tilt Can Cause Misinterpretation of the Acetabular Index Measured on Radiographs

BackgroundRadiographic diagnosis and followup studies of developmental dysplasia of the hip are commonly performed by measuring the acetabular index on radiographs using Hilgenreiner’s method. The outcome of the measurement, however, depends on the orientation of the subject’s pelvis relative to the xray source. The influence of pelvic rotation and tilt on the measurement error has been evaluated separately but not in combination.Questions/purposesWe asked whether (1) combinations of pelvic rotation and tilt introduced systematic error in acetabular index measurement in a reproducible way, and (2) ratios proposed to evaluate either pelvic rotation (Rrotation) or pelvic tilt (Rtilt) are influenced by pelvic tilt and rotation, respectively.MethodsRadiographic measurements of the acetabular index, Rrotation, and Rtilt were performed on digitally reconstructed radiographs of one high-resolution three-dimensional CT dataset with various combinations of pelvic rotation and tilt.ResultsFor rotations and tilt up to 12°, the average systematic errors in the acetabular index varied from −8.8° to 4.5°. Negative and positive error values can be interpreted as underestimations and overestimations of the acetabular index, respectively. Errors in acetabular index measurements were acceptable for Rrotation values between 1.0 and 2.0 and Rtilt values between 1.1 and 1.8.ConclusionsTo limit the systematic error in assessing the acetabular index caused by pelvic misalignment, we recommend only radiographs acquired with ± 4° rotation and ± 4° tilt be considered acceptable.

Diagnosis of acetabular dysplasia in infancy

In 98 infants at the age of 3-4 months acetabular dysplasia without decentration was diagnosed by means of combined method of Schultheiss/wedge-shaped segments/ and Doberti and Manhood/acetabular defects/. This method was confronted with the classical procedure using measurements of acetabular index and with other radiological and clinical signs. It is concluded that the only reliable sign of acetabular dysplasia at the age of 3-4 months is the disturbance of ossification at the end of the acetabular roof in the sense of partial or total defects. All other radiological as well as clinical signs including acetabular index values, asymmetry of gluteal folds and limitation of abduction in the hip joints are shown to be of little or no importance.

Prediction of acetabular development after closed reduction by overhead traction in developmental dysplasia of the hip

BackgroundThe prediction of acetabular development after reduction of developmental dysplasia of the hip (DDH) is important to ensure optimal timing of acetabuloplasty and to avoid unnecessary surgery. The objective of this study was to find early and reliable predictors of future acetabular dysplasia in the hips reduced by overhead traction (OHT). MethodsWe retrospectively reviewed 45 hips in 40 patients treated by OHT for DDH without additional procedures. The average age at the time of closed reduction was 9.3months, and the average age at the latest examination was 17.3years. Residual hip dysplasia at skeletal maturity was defined according to Severin’s classification. The following variables were evaluated as possible predictors of the final outcome: age at reduction, severity of the dislocation, serial measurements of acetabular index (AI), center-edge angle of Wiberg (CE), and the center-head discrepancy distance (CHDD). ResultsSixty-two percent of the hips had satisfactory results in Severin I/II and 38% had unsatisfactory results in Severin III. Bilateral DDH showed significantly poorer outcome than unilateral DDH. The average AI of the unsatisfactory group was significantly greater than that of the satisfactory group at 4years or more after reduction. Similarly, the average CE of the satisfactory group was greater than that of the unsatisfactory group at 5years or more after reduction. In unilateral cases, the AI and the CE of the uninvolved hip at 1year after reduction also correlated with the final outcome of the involved hip. ConclusionsThe AI of 4years and the CE of 5years after reduction were the earliest predictors of the final outcome. Careful consideration for the need of acetabuloplasty would be given at 4 or 5years after reduction by OHT. Bilateral DDH and poor acetabular coverage of the uninvolved hip in unilateral DDH were the prognostic factors of unfavorable acetabular development of the dislocated hip.