Evaluation of experienced surgeons' decisions regarding the need for secondary surgery in developmental dysplasia of the hip

The role of the cartilaginous to osseous acetabular angle ratio in children with developmental dysplasia of the hip

Purpose

This study aims to demonstrate the use of the cartilaginous to osseous acetabular angle ratio (AAR) in surgical decision-making for hip dysplasia.

Methods

Data were collected from patients who underwent an MRI of the hip after conservative treatment for developmental dysplasia of the hip between August 2019 and 2022. The data included demographic information as well as an anteroposterior pelvic radiograph. The osseous acetabular index (OAI) was measured using x-ray, while the cartilaginous acetabular index (CAI) and the cartilaginous acetabulum head index (CAHI) were measured using MRI. The square of the CAI to OAI, AAR, was calculated. The patients in the residual hip dysplasia (RHD) group were categorized as having an OAI above 20°. During the postoperative follow-up, we evaluated the patients in this group who underwent Bernese triple pelvic osteotomy. Data on surgical patients with an observation period that exceeded 1 year were collected and analyzed. The distribution of the AAR among the different groups was analyzed. A receiver operating characteristic (ROC) predictive model was constructed using the AAR of the patients in the normal and surgical groups to evaluate the need for surgery.

Results

It was found that there was a significant difference in the OAI, CAI, CAHI, and AAR between the RHD group (OAI 26.15 ± 3.90°, CAI 11.71 ± 4.70°, CAHI 79.75 ± 6.27%, and AAR 5.88 ± 4.24) and the control group patients (OAI 16.77 ± 5.39°, CAI 6.16 ± 3.13°, CAHI 85.05 ± 4.91%, and AAR 2.71 ± 2.08) (p < 0.001). A total of 93.5% of the control group patients had an AAR ≤5, while only 6.5% had an AAR >5. The results of postoperative imaging follow-up were "excellent" in 52 patients and "good" in 3, while the functional follow-up results were excellent in 53 and good in 2. In 15 patients, the observation period exceeded 1 year. The mean observation period was 633.1 ± 259.6 days and the preoperative CAHI was 71.7 ± 4.8%. Of the patients with an AAR >5, a substantial 94.8% (55/58) of them were reported to have undergone surgery, while all patients with an AAR less than or equal to 5 did not undergo surgery (91/91). Based on the ROC, a cutoff value of 5.09 was identified for the need for surgery in children with RHD.

Conclusions

A surgical decision for residual hip dysplasia can be based on the AAR. An AAR >5 may be a potential indicator for surgical intervention in patients with RHD.

Hip dysplasia hiding in plain sight: A retrospective analysis of radiology reports

INTRODUCTION

Timely recognition of dysplastic hip morphology is critical to facilitate appropriate management before significant joint damage has developed. It is likely that radiologist under reporting contributes to delays in diagnosis. This study aimed to assess how often adult hip dysplasia goes undetected in radiological reports and to identify clinical and radiological variables that impact the likelihood of detection of dysplasia by radiologists.

METHODS

Referral details and radiology reports of patients who underwent periacetabular osteotomy by a single surgeon for symptomatic hip dysplasia between 1 January 2016 and 30 June 2020 were reviewed. Four assessors measured the lateral centre edge angle from the pelvic radiograph performed at time of referral. Film quality and other radiographic parameters were also assessed.

RESULTS

Sixty-eight patients were included, 84% were female and the median age was 28.1 years. Dysplasia was not documented in the radiology report in 49% of cases. Dysplasia was more likely to be reported with no history of injury, an aspherical femoral head, lower lateral centre edge angle, higher acetabular index, increased femoral head shaft angle, higher femoro-epiphyseal acetabular roof index, or if there was disruption of Shenton's line, with the first three variables being independent predictors of radiologist detection.

CONCLUSION

Hip dysplasia should be considered in all adolescents/young adults presenting with hip pain. Causes of radiologist under reporting are likely multifactorial. Clinical information can cause cognitive biases and result in selective looking. A systematic approach to pelvis radiographs should include assessment of acetabular coverage and active search for evidence of femoral head migration.

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

Aims

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

Methods

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

Results

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

Conclusion

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

MRI May Be More Valuable than Pelvic Radiographs in the Assessment of Paediatric Borderline Acetabular Dysplasia

The osseous acetabular index (OAI) and cartilaginous acetabular index (CAI) is often used in diagnosing acetabular dysplasia (AD) in children. We examined the reliability of OAI and CAI in AD diagnostics and compared OAI measurements obtained from radiographs versus MRI. Four raters performed retrospective repeated measurements of the OAI and CAI on pelvic radiographs and MRI scans of 16 consecutive patients (mean age 5 years (2-8)) examined for borderline AD during a period of 2½ years. In MRI, the image selected for analysis by the raters was also registered. Spearman's correlation, scatter plots, and Bland-Altman (BA) plots were analysed for correlation between OAI on pelvic radiographs (OAIR) and MRI scans (OAIMRI), while intra- and interrater reliability was assessed for OAIR, OAIMRI, CAI, and MRI image selection using intraclass correlation coefficients (ICC). ICC values for inter- and intrarater reliability of OAIR, OAIMRI, and CAI were all above 0.65, with no significant differences observed. ICC values (CI) for individual raters' MRI image selection was 0.99 (0.998-0.999). The mean difference (95% CI) between OAIR and OAIMRI was -0.99 degrees (-1.84; -0.16), while the mean absolute difference (95% CI) between OAIR and OAIMRI was 3.68 degrees (3.17; 4.20). Absolute differences between OAIR and OAIMRI was independent of pelvic positioning or time interval between radiographs and MRI scans. OAI and CAI had high Intrarater reliability but mediocre interrater reliability. There was an absolute difference of 3.7 degrees in OAI between pelvic radiographs and MRI scans.

Redislocation After Posteromedial Open Reduction in Developmental Dysplasia of the Hip: Analyzing the Risk Factors and Determining the Optimal Treatment Method

BACKGROUND

Redislocation, which is one of the most serious problems in developmental dysplasia of the hip (DDH), might occur because of several reasons. Regardless of the treatment, redislocations are reported to be associated with high complication rates in the literature. Our objective was to identify the risk factors for redislocation in the patients treated for DDH and to determine the optimal treatment method for redislocations.

METHODS

Patients with DDH who were treated with the limited posteromedial approach in our clinic between 1993 and 2021 and followed up prospectively were examined in this single-centered study. The participants were assigned into 2 groups: a study group consisting of 25 hips of 17 patients with redislocation and a control group consisting of 502 hips of 390 patients without redislocation. To determine the risk factors for redislocation, demographic data, known risk factors for DDH, preoperative Tönnis stage, and whether the capsule was opened or not were evaluated. To determine the optimal treatment method, a subgroup analysis based on applied treatment (closed reduction and cast replacement vs. repeating open reduction) was conducted, and recurrent redislocation, complication, and secondary surgery rates were evaluated.

RESULTS

Bilaterality and high-grade hip dislocations were found to be associated with higher odds ratio (OR) for redislocation [ P =0.007, OR=3.64, 95% confidence interval (CI), 1.3 to 8.8; and P =0.006, OR=4.52, 95% CI, 1.37 to 14.91, respectively]. Recurrent redislocation and complication rates were found to be significantly higher in redislocations treated with closed reduction and cast replacement ( P =0.007 and P =0.015, respectively).

CONCLUSIONS

Bilaterality and higher preoperative Tönnis stage are critical risk factors for redislocation after open reduction in DDH. It should be kept in mind that closed reduction and cast replacement is associated with higher rates of recurrent redislocation and complications, and redislocation cases should be treated by repeating open reduction.

LEVEL OF EVIDENCE

Level II-therapeutic study.

MRI-based synthetic CT shows equivalence to conventional CT for the morphological assessment of the hip joint

This study evaluated the accuracy of synthetic computed tomography (sCT), as compared to CT, for the 3D assessment of the hip morphology. Thirty male patients with asymptomatic hips, referred for magnetic resonance (MR) imaging and CT, were included in this retrospective study. sCT images were generated from three-dimensional radiofrequency-spoiled T1-weighted multi-echo gradient-echo MR images using a commercially available deep learning-enabled software and were compared with CT images through mean error and surface distance computation and by means of eight clinical morphometric parameters relevant for hip care. Parameters included center-edge angle (CEA), sharp angle, acetabular index, extrusion index, femoral head center-to-midline distance, acetabular version (AV), and anterior and posterior acetabular sector angles. They were measured by two senior orthopedic surgeons and a radiologist in-training on CT and sCT images. The reliability and agreement of CT- and sCT-based measurements were assessed using intraclass correlation coefficients (ICCs) for absolute agreement, Bland-Altman plots, and two one-sided tests for equivalence. The surface distance between CT- and sCT-based bone models were on average submillimeter. CT- and sCT-based measurements showed moderate to excellent interobserver and intraobserver correlation (0.56 < ICC < 0.99). In particular, the inter/intraobserver agreements were good for AV (ICC > 0.75). For CEA, the intraobserver agreement was good (ICC > 0.75) and the interobserver agreement was moderate (ICC > 0.69). Limits of agreements were similar between intraobserver CT and intermodal measurements. All measurements were found statistically equivalent, with average intermodal differences within the intraobserver limits of agreement. In conclusion, sCT and CT were equivalent for the assessment of the hip joint bone morphology.

Docking phenomenon and subsequent acetabular development after gradual reduction using overhead traction for developmental dysplasia of the hip over six months of age

PURPOSE

This study aimed to explore the docking of the femoral head into the acetabulum after gradual reduction (GR) using traction for developmental dysplasia of the hip (DDH) and the impact on subsequent acetabular development.

METHODS

A total of 40 patients with DDH (42 hips) undergoing GR using overhead traction and spica casting were retrospectively reviewed. The presence of inverted labrum and the coronal and axial femoral-acetabular distances (FADs) were compared between MRI immediately and five weeks after spica casting. The change in the acetabular index on anteroposterior pelvic radiographs were compared between hips with inverted labrum (residual group) and with normally-shaped labrum (normalized group) on follow-up MRI.

RESULTS

The mean age at reduction was 13.1 months (7 to 33) and the mean follow-up duration was 7.7 years (4 to 11). The rate of inverted labrum and the FADs significantly decreased between the MRI scans (all p-values < 0.001), and previous Pavlik harness failure had no negative effect on these decreases. The acetabular indices at the ages of three and five years in the residual group were significantly larger than those in the normalized group (both p-values < 0.001). Residual acetabular dysplasia was seen in 84.2% of the residual group compared with 34.8% of the normalized group (p = 0.002).

CONCLUSION

The docking phenomenon can occur during spica casting following GR using traction in children with DDH between the ages of six months and three years. The remaining inverted labrum at the cast removal may negatively affect subsequent acetabular development.

LEVEL OF EVIDENCE

III - retrospective comparative study.

What is the association between MRI and conventional radiography in measuring femoral head migration?

Background and purpose - Pelvic radiographs are traditionally used for assessing femoral head migration in residual acetabular dysplasia (RAD). Knowledge of the heightened importance of cartilaginous structures in this condition has led to increased use of MRI in assessing both osseous and cartilaginous structures of the pediatric hip. Therefore, we assessed the relationship between migration percentages (MP) found on MRI and conventional radiographs. Second, we analyzed the reliability of MP in MRI and radiographs.Patients and methods - We retrospectively identified 16 patients (mean age 5 years [2-8], 14 girls), examined for RAD during a period of 2½ years. 4 raters performed blinded repeated measurements of osseous migration percentage (MP) and cartilaginous migration percentage (CMP) in MRI and radiographs. Pelvic rotation and tilt indices were measured in radiographs. Bland-Altman (B-A) plots and intraclass correlation coefficients (ICC) were calculated for agreement and reliability.Results - B-A plots for MPR and MPMRI produced a mean difference of 6.4 with limits of agreement -11 to 24, with higher disagreements at low average MP values. Mean MPR differed from mean MPMRI (17% versus 23%, p < 0.001). MPR had the best interrater reliability with an ICC of 0.92 (0.86-0.96), compared with MPMRI and CMP with ICC values of 0.61 (0.45-0.70) and 0.52 (0.26-0.69), respectively. Intrarater reliability for MPR, MPMRI and CMP all had ICC values above 0.75 and did not differ statistically significantly. Differences inMPMRI and MPR showed no correlation to pelvic rotation index, pelvic tilt index, or interval between radiograph and MRI exams.Interpretation - Pelvic radiographs underestimated MP when compared with pelvic MRI. We propose CMP as a new imaging measurement, and conclude that it has good intrarater reliability but moderate interrater reliability. Measurement of MP in radiographs and MRI had mediocre to excellent reliability.

Simultaneous bilateral single-stage combined open reduction and pelvic osteotomy for the treatment of developmental dysplasia of the hip

Children older than 18 months with developmental dysplasia of the hip (DDH) for the first time or who do not respond to closed treatment require open reduction with/without acetabuloplasty. We determined whether open reduction and pelvic acetabuloplasty using the Pemberton or Dega technique for both hips simultaneously was well tolerated and offered better outcomes. A total of 140 hips of 70 patients with bilateral DDH were identified. All patients were diagnosed after they started walking. Patients were treated with bilateral single-stage open reduction with acetabuloplasty using the Pemberton or Dega procedure. All patients were prospectively followed up between 2007 and 2018. Results were considered satisfactory if the acetabular index was <24°. Hemoglobin levels were evaluated in all patients. At the final follow-up, the results were evaluated radiologically and clinically based on the modified Severin's classification and modified McKay criteria, respectively. The mean age at surgery was 20.3 months (range, 16-24). The mean operative time was 228 minutes. The mean postoperative hemoglobin level was 90.5 g/L (range, 61-122; SD, ±13.4). The mean differences between the preoperative and postoperative acetabular index values for both hips were 22.36° (SD, ±6.69°) and 22.64° (SD, ±6.69°) for the right and left hips, respectively. Open reduction with pelvic acetabuloplasty using the Pemberton or Dega technique simultaneously in both hips was well tolerated, cost-effective, had excellent outcomes, and posed no additional risk to patients with DDH younger than 24 months.

Treatment of developmental dysplasia of the hip (DDH) between the age of 18 and 24 months

BACKGROUND

Treatment of developmental dysplasia of the hip between the age of 6 and 18 months starts with closed reduction (CR). If CR is not attainable, open reduction is performed. Open reduction and pelvic osteotomy (ORPO) is usually done directly after the age of two. The aim of this study is to evaluate CR compared to ORPO with respect to early radiographic outcome in patients aged 18 to 24 months at reduction.

METHODS

A single-surgeon cohort was reviewed. Inclusion criteria were age between 18 and 24 months, no prior treatment and minimal follow-up of 2 years. Hips that were not displaced or had a nonidiopathic cause were excluded. Residual dysplasia was defined as a center edge angle (CEA) of less than 15° or CEA less than 20° with an acetabular index (AI) of more than 30°. Multiple regression was used, the outcome was follow-up CEA, and the explanatory variables were age, sex, type of surgery, international hip dysplasia grade and preoperative AI. Values of preoperative AI in the CR group and follow-up CEA were plotted.

RESULTS

Eighty-two hips in fifty patients were included. Residual dysplasia was identified in 16 hips (20%), 12 (27%) after CR, and 4 (11%) after ORPO (p = 0.10). Recurrence and avascular necrosis rates were not statistically different. Preoperative AI and type of surgery independently affected CEA. CR patients with a preoperative AI of more the 40° had a 50% (10/20) risk of residual dysplasia.

CONCLUSION

CR is an important option to consider in selected patients between the age of 18 and 24 months and the selection should not be based on intraoperative assessment only, but also on preoperative measurement of AI.

LEVEL OF EVIDENCE

Level III.

Residual hip dysplasia in children: osseous and cartilaginous acetabular angles to guide further treatment-a pilot study

PURPOSE

In case of residual hip dysplasia (RHD) in children, pelvic radiographs are sometimes insufficient to precisely evaluate the entire coverage of the femoral head, when trying to decide on the need for further reconstructive procedures.

METHODS

This study retrospectively compares the bony and the cartilaginous acetabular angle of Hilgenreiner (HTE) of 60 paediatric hips on pelvic MRI separated in two groups. Group 1 included 31 hips with RHD defined by a bony HTE > 20°. Group 2 included 27 hips with a HTE < 20°. They were compared by introducing a new ratio calculated from the square of cartilaginous HTE above the bony HTE on frontal MRI. The normal upper limit for this acetabular angle ratio was extrapolated from the published normal values of cartilaginous HTE and bony HTE in children.

RESULTS

The acetabular angle ratio was statistically significantly increased in the hips with RHD with a mean value of 7.1 ± 4.7 compared to the hips in the control group presenting a mean value of 2.1 ± 1.9 (p < 0.00001).

CONCLUSIONS

This newly introduced ratio seems to be a helpful tool to orientate the further treatment in children presenting borderline RHD.

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

PURPOSE

The 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).

METHODS

From 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.

RESULTS

The 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.

CONCLUSION

Both AI-S and AI-L methods are equally reliable radiographic measures of DDH.

LEVEL OF EVIDENCE

Level III (diagnostic).

The Utility of False-Profile Radiographs for the Detection of Osteoarthritis Progression in Acetabular Dysplasia

Background:

Both the lateral center-edge angle and acetabular roof obliquity on anteroposterior radiographs are well-known prognostic predictors of osteoarthritis progression in patients with acetabular dysplasia. However, few studies have evaluated osteoarthritis progression on false-profile radiographs. In the present study, osteoarthritis progression was evaluated on anteroposterior and false-profile radiographs.

Methods:

We retrospectively evaluated 76 patients with acetabular dysplasia with Tönnis grade-0 or 1 osteoarthritis, from a group of 179 patients (209 hips), who had undergone unilateral periacetabular osteotomy from 1995 to 2005. We evaluated the hip joint of the contralateral, untreated side. All patients were followed for ≥10 years. Of the 76 patients, 52 patients with Tönnis grade-0 or 1 osteoarthritis at the latest follow-up were categorized into the non-progression group and the remaining 24 patients with Tönnis grade-2 or 3 osteoarthritis were categorized into the progression group. We evaluated patient characteristics as well as radiographic parameters, including the preoperative lateral center-edge angle, acetabular roof obliquity, and anterior center-edge angle.

Results:

The mean duration of follow-up was 12.6 years (range, 10 to 19 years). On univariate analysis, body weight, body mass index, and all radiographic parameters indicating the severity of acetabular dysplasia significantly differed between the 2 groups. On multivariate analysis, both the anterior center-edge angle and acetabular roof obliquity were considered to be significant predictive factors for osteoarthritis progression. On receiver operating characteristic curve analysis, the cutoff values for the lateral center-edge angle, acetabular roof obliquity, and anterior center-edge angle were 15.5°, 15.5°, and 12.5°, respectively.

Conclusions:

In addition to the lateral center-edge angle and acetabular roof obliquity, we showed that the anterior center-edge angle is a possible prognostic predictor of osteoarthritis progression. These findings indicate that radiographic parameters based on the false-profile view are relevant. Additionally, patients with an anterior center-edge angle of ≤12.5° and a lateral center-edge angle of ≤15.5° seem to be at higher risk of osteoarthritis progression over a 10-year period.

Level of Evidence:

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

Magnetic resonance imaging evaluation of the labrum to predict acetabular development in developmental dysplasia of the hip: A STROBE compliant study

Recently, more attention has been paid to the role of the acetabular labrum. Therefore, we designed a retrospective cohort study of patients with residual hip dysplasia (RHD) who underwent magnetic resonance imaging (MRI). The objective of this study was to investigate an association between the MRI appearance of the labrum before school age and the natural history of RHD.We retrospectively investigated 45 hips of 40 patients who underwent MRI at about 3 and 4 years of age for RHD and were conservatively followed up with until 6 years of age or older. We evaluated the extent of eversion with a new method that measures the β angle (MRI β angle) using landmarks of the Graf method on MRI T2*-weighted images. The outcome measure was the Severin classification at the final follow-up. We compared the radiographic and MRI parameters at approximately 3 and 4 years of age between the good and poor outcome groups. The Student t test or one-way analysis of variance was used to compare the quantitative variables between groups. The Chi-square test was used to perform a ratio comparison.Although there was a significant difference in the center-edge (CE) angle, there was no significant difference in the acetabular index and the ratio of the presence of femoral head necrosis and the break in Shenton line between the good and poor groups. The MRI β angle was significantly greater in the poor outcome group than in the normal and good outcome groups. The cut-off value of the MRI β angle to differentiate the good and poor outcome groups was 65°, and its specificity and sensitivity were 92% and 53%, respectively.There was labral eversion on MRI scans in patients with RHD. Acetabular development before adolescence was poorer with greater labral eversion on MRI scans. The specificity for poor acetabular development was high when the MRI β angle was 65° or more. The MRI β angle has the potential to predict acetabular development.

Normal values of bony, cartilaginous, and labral coverage of the infant hip in MR imaging

BACKGROUND

Magnetic resonance imaging (MRI) is becoming more popular in the evaluation of residual hip dysplasia. Normal values of the bony, cartilaginous, and labral coverage in MRI are not published. The aim of our study was to establish reference values for normal hips at different ages and to assess the interobserver variability of such measurements.

METHODS

MRIs of 115 normal hips in 73 children were analyzed. The bony, cartilaginous, and labral acetabular index (AI bone/cartilage/labrum) was measured in the coronal plane just posterior to the inferior branch of the triradiate cartilage. To determine interobserver variability, measurements were made by 3 different observers. Percentile graphs were established from the Student t distribution of the measurements grouped by 2 years of age.

RESULTS

Global interobserver variability for the measurement of the AI bone was excellent [intraclass correlation coefficient (ICC)=0.88]. For the AI cartilage and labrum the ICC was somewhat lower (ICC 0.78) but still rated as good. Age-dependent percentile graphs of the AI bone, cartilage, and labrum are presented. Although the AI bone decreased during childhood, the AI cartilage as well as the AI labrum stays relatively constant with the 50 percentile around 5 degrees for the AI cartilage and -5 degrees for the AI labrum. The 90 percentile is around 10 degrees for the AI cartilage and 0 degrees for the AI labrum.

CONCLUSIONS

We present percentile graphs of age-related normal values. Although bony coverage increases during childhood, cartilaginous and labral coverage stay constant. We think that measuring an AI cartilage above 10 degrees or an AI cartilage above 0 degrees might be a good additional parameter to classify hips into the group of residual dysplasia.

CLINICAL RELEVANCE

The knowledge of normal values for cartilaginous and labral coverage is a valuable adjunct in decision-making for secondary surgery in residual dysplasia. This was a retrospective cross-sectional study.

How are outcomes affected by performing a one-stage combined procedure simultaneously in bilateral developmental hip dysplasia?

PURPOSE

The aim of this study was to compare the outcomes of one-stage combined surgical treatment in children of unilateral and bilateral developmental hip dysplasia diagnosed after walking age.

METHODS

We reviewed 24 patients who underwent one-stage combined surgery for DDH diagnosed after walking age. Group I consisted of 12 patients with bilateral disease who underwent bilateral operation at one operative setting. Group II consisted of 12 patients with unilateral disease. Pre-operatively the hips were classified according to Tönnis classification. Acetabular dysplasia was evaluated by measuring acetabular index (AI) angles pre-operatively. The acetabular improvements with time regarding AI was noted immediately postoperatively, every six months, and at the final follow-up examination.

RESULTS

Mean follow up of the bilateral group I and group II were 54.8 months (range 20-84 months) and 52.6 months (24-80), respectively. There were no statistically significant differences between immediate postoperative and final follow up acetabular index improvement rates in both groups. Also there was no significant difference when both hips were compared in group I. The clinical final outcome of both groups and within group I was similar.

CONCLUSIONS

Simultaneous combined surgery is a challenging but worthwhile procedure for late diagnosed patients with bilateral DDH. The short-mid term outcomes of the procedure are encouraging.

Comparison of soft-tissue and bone surgeries in the treatment of developmental dysplasia of the hip in 18-24-month-old patients

The aim of this study was to compare soft-tissue and bone surgeries in 18-24-month-old patients with developmental dysplasia of the hip (DDH). A total of 77 hips of 53 patients were analyzed. Soft-tissue surgery was performed in 31 hips of 25 patients. In the final examination, 23 hips, excluding hips of eight patients who underwent secondary bone surgery, were evaluated (group I). Bone surgery was performed on 46 hips of 28 patients (group II). In group I, the acetabular index was 41° preoperatively and was 20.4° in the final examinations. In group II, the acetabular index was 42° preoperatively and was 15° in the final examinations. To avoid unnecessary surgeries and complications, soft-tissue surgery should be preferred for DDH in 18-24-month-old patients.

Femoral head deformity and severity of acetabular dysplasia of the hip

Patients with acetabular dysplasia commonly undergo peri-acetabular osteotomy after skeletal maturity to reduce the risk of the late development of osteoarthritis. Several studies have suggested that deformity of the femoral head influences the long-term outcome. We radiologically examined 224 hips in 112 patients with acetabular dysplasia and early-stage osteoarthritis. There were 103 women and nine men with a mean age of 37.6 years (18 to 49). A total of 201 hips were placed in the acetabular dysplasia group and 23 in a normal group. The centre–edge angle and acetabular head index were significantly smaller (both p < 0.001), and the acetabular angle, acetabular roof angle and roundness index were significantly greater in the acetabular dysplasia group than those in the normal group (all p < 0.001). There were significant correlations between the roundness index and other parameters. Femoral head shape may be influenced by the severity of the acetabular dysplasia.

Cite this article: Bone Joint J 2013;95-B:1192–6.