Evaluation of Acetabular Development Following Open Reduction of Developmental Dysplasia of Hip in Children After Walking Age

Background and purposeThe growth and development of the acetabulum in children with developmental dysplasia of hip (DDH) depends upon the extent of concentric reduction. Children in walking age often need open reduction with or without additional osteotomies to obtain congruous, stable reduction. The purpose of this study was to evaluate acetabular development in late diagnosed DDH treated by open reduction with or without femoral osteotomy.MethodsThis is a retrospective study of 29 children (40 hips) with idiopathic DDH, previously untreated managed by open reduction with or without femoral osteotomy. We analyzed preoperative and yearly postoperative radiographs up to 6 years of age for acetabular development by measuring acetabular index. Acetabular remodeling was assessed with a graphical plot of serial mean acetabular index. Those with AI < 30° at outcome measure point of 6 years of patient age were considered to have satisfactory acetabular remodeling.ResultsMean age of surgery was 26.8 months. Open reduction alone was done in 14 hips and open reduction with concurrent femoral osteotomy done in 26 hips. The mean acetabular index pre operatively was 36.6° ± 5.9° which reduced to 29.7° ± 6° at 1-year follow-up and to 26.6° ± 5.9° at 2-year follow-up. 28 out of 40 hips were available for evaluation at outcome measure point of 6 years of age, which showed satisfactory remodeling in 24 hips with mean AI of 22.7° ± 5.7°. Maximum acetabular development was seen at 2 years post-surgery and better remodeling was seen in children operated at less than 2 years of age. 5 hips had changes of avascular necrosis of femoral head. There was no incidence of redislocation/subluxation at latest follow-up.ConclusionOpen reduction in late-diagnosed developmental dysplasia of hip has potential for favourable acetabular development. Femoral osteotomy when required along with open reduction may suffice to address acetabular dysplasia found in the initial years of management of DDH.     

CT Based Analysis of Acetabular Morphology in Northern Indian Population: A Retrospective Study

PurposeThe acetabular morphology has shown to differ among different regions of the world. Multiplanar evaluation by computed tomography (CT) scan is the key to assess acetabular depth, version, and inclination at the same time which have been rarely explored before in the Indian population. We present an anthropometric study of the native acetabulum by CT based coronal, sagittal, and axial parameters in the Northern Indian population.MethodsThe acetabular anteversion (AA), acetabular angle of sharp (AAS), sagittal acetabular angle (SAA), lateral center edge angle (LCEA), acetabular depth (AD), acetabular horizontal offset (AHO), extrusion index (EI) and acetabular depth ratio (ADR) was measured in CT scans of 122 patients (244 hips) without any bony pathologies. LCEA < 20°, ADR < 250, AD < 9 mm, AAS > 43°, and EI ≥ 25% were taken as criteria for dysplastic acetabulum.ResultsThere were 62 males and 60 females included in the study with a mean age of 63.8 ± 17.2 years (21–98 years). In this study, females were having significantly lower ADR (p = 0.002) and higher EI (p = 0.01) than males. The prevalence of dysplasia was 3.2% according to LCEA and 1.6% while combining all of the criteria.ConclusionThere are prominent differences in acetabular depth in the Indian population compared with the population of Western countries or other parts of Asia. Females were shown to have shallower acetabulum than males. The comparative analysis of radiographic parameters obtained from our study with the data available on different country-based studies can help better understanding the acetabular morphology of Indian as well as the worldwide population.Level of StudyRetrospective cross-sectional study.     

The Development of Leg Length Difference and Influence on Persistent Dysplasia in Patients with Developmental Dysplasia of the Hip

IntroductionLeg-length difference (LLD) is common in patients with developmental dysplasia of the hip (DDH). LLD of > 1 cm at skeletal maturity is reported in > 40% of patients, with the majority related to ipsilateral overgrowth. A longer DDH leg might lead to excessive mechanical loading at the acetabular margin, resulting in compromised acetabular development. We hypothesised that the LLD would negatively influence acetabular development. If so, it would be advantageous to identify such patients early in the course of follow-up, and address this if necessary.MethodsA retrospective study was conducted on a consecutive series of DDH patients managed surgically at the Royal National Orthopaedic Hospital, Stanmore, United Kingdom. We included patients with adequate long-leg radiographs at the age of 4–8 years (early-FU) and skeletal maturity (final-FU). Bilateral cases and those who underwent surgical procedures for hip dysplasia during the follow-up period were excluded. Measurements including leg length and centre-edge-angle (CE-angle) were obtained at the 2 time points.ResultsTwenty-seven patients were included, mean age at early-FU 5.7 (± 0.9) years, and 13.9 (± 1.0) years at final-FU. Mean LLD at early-FU was 9.5 (± 7.6) mm and 10.9 (± 9.4) mm at final-FU, p = 0.337. Correlation between early- and final-FU LLD was 0.68 (p < 0.001). The mean CE-angle at early follow-up was 14.6° (± 9.8), this improved to 23.2° (± 8.2) at skeletal maturity (p = 0.003, paired samples t-test). Linear regression analysis showed a non-significant trend towards less CE-angle improvement in patients with more initial residual dysplasia and more initial LLD.ConclusionMost leg-length differences can be identified early in the follow-up period, nevertheless, considerable individual changes in LLD are observed on continued follow-up. Furthermore, a trend was observed towards impaired acetabular improvement in patients with more LLD. These findings justify careful clinical and radiological monitoring of LLD from an early stage in the follow-up period.Supplementary InformationThe online version contains supplementary material available at 10.1007/s43465-021-00492-5.     

A Comparative Study of Clinical and Radiological Outcomes of Open Reduction Using the Anterior and Medial Approaches for the Management of Developmental Dysplasia of the Hip

BackgroundThe literature is scanty on reports directly comparing the outcomes of anterior open reduction (AOR) and medial open reduction (MOR) in the management of developmental dysplasia of the hip (DDH).Purpose of the StudyTo compare clinical and radiographic outcomes of surgical treatment using either AOR or MOR in children with DDH aged < 24 months and to evaluate the procedure-inherent risks of avascular necrosis of the femoral head (AVN) and need for further corrective surgery (FCS).Methods61 children who underwent surgical treatment for DDH were categorized into two groups: AOR (31 hips of 28 patients) and MOR (39 hips of 33 patients). The mean age was 17 ± 5.85 (range 7–24) months in group AOR and 13 ± 5.31 (range 6–24) months in group MOR. The mean follow-up was 118 ± 41.2 (range 24–192) months and 132 ± 36.7 (range 24–209) months in group AOR and MOR. At the final follow-up, mid- to long-term clinical and radiographic outcomes were assessed. FCS was recorded.ResultsRegarding McKay’s clinical criteria, both groups exhibited similar results (p = 0.761). No significant differences were observed between the groups in both the center–edge–angle (p = 0.112) and the Severin score (p = 0.275). The AVN rate was 32% in the AOR group and 20% in the MOR group (p = 0.264). The FCS rate was 22% in the AOR group and 12% in the MOR group (p = 0.464).ConclusionsThis study showed similar clinical and radiological outcomes with AOR and MOR with no significant relation to AVN and FCS.Level of EvidenceLevel III.     

What Are the Radiographic Reference Values for Acetabular Under- and Overcoverage?

BackgroundBoth acetabular undercoverage (hip dysplasia) and overcoverage (pincer-type femoroacetabular impingement) can result in hip osteoarthritis. In contrast to undercoverage, there is a lack of information on radiographic reference values for excessive acetabular coverage.Questions/purposes(1) How do common radiographic hip parameters differ in hips with a deficient or an excessive acetabulum in relation to a control group; and (2) what are the reference values determined from these data for acetabular under- and overcoverage?MethodsWe retrospectively compared 11 radiographic parameters describing the radiographic acetabular anatomy among hip dysplasia (26 hips undergoing periacetabular osteotomy), control hips (21 hips, requiring no rim trimming during surgical hip dislocation), hips with overcoverage (14 hips, requiring rim trimming during surgical hip dislocation), and hips with severe overcoverage (25 hips, defined as having acetabular protrusio). The hips were selected from a patient cohort of a total of 593 hips. Radiographic parameters were assessed with computerized methods on anteroposterior pelvic radiographs and corrected for neutral pelvic orientation with the help of a true lateral radiograph.ResultsAll parameters except the crossover sign differed among the four study groups. From dysplasia through control and overcoverage, the lateral center-edge angle, acetabular arc, and anteroposterior/craniocaudal coverage increased. In contrast, the medial center-edge angle, extrusion/acetabular index, Sharp angle, and prevalence of the posterior wall sign decreased. The following reference values were found: lateral center-edge angle 23° to 33°, medial center-edge angle 35° to 44°, acetabular arc 61° to 65°, extrusion index 17% to 27%, acetabular index 3° to 13°, Sharp angle 38° to 42°, negative crossover sign, positive posterior wall sign, anterior femoral head coverage 15% to 26%, posterior femoral head coverage 36% to 47%, and craniocaudal coverage 70% to 83%.ConclusionsThese acetabular reference values define excessive and deficient coverage. They may be used for radiographic evaluation of symptomatic hips, may offer possible predictors for surgical outcomes, and serve to guide clinical decision-making.

Level of Evidence

Level III, diagnostic study.     

Does Radiographic Coxa Profunda Indicate Increased Acetabular Coverage or Depth in Hip Dysplasia?

Background

Although radiographic coxa profunda has been considered an indicator of acetabular overcoverage, recent studies suggest that radiographic coxa profunda is a nonspecific finding seen even in hip dysplasia. The morphologic features of coxa profunda in hip dysplasia and the frequency with which the two overlap are not well defined.

Questions/purposes

We determined (1) the prevalence of radiographic coxa profunda in patients with hip dysplasia; (2) the morphologic differences of the acetabulum and pelvis between patients with hip dysplasia and control subjects; and (3) the morphologic differences between hip dysplasia with and without coxa profunda.

Methods

We retrospectively reviewed the pelvic radiographs and CT scans of 70 patients (70 hips) with hip dysplasia. Forty normal hips were used as controls. Normal hips were defined as those with a lateral center-edge angle between 25° and 40°. Coxa profunda was defined as present when the acetabular fossa was observed to touch or was medial to the ilioischial line on an AP pelvic radiograph. CT measurements included acetabular version, acetabular coverage, acetabular depth, and rotational alignment of the innominate bone.

Results

The prevalence of coxa profunda was 44% (31 of 70 hips) in dysplastic hips and 73% (29 of 40 hips) in the control hips (odds ratio, 3.32; 95% CI, 1.43–7.68). Dysplastic hips had a more anteverted and globally shallow acetabulum with inwardly rotated innominate bone compared with the control hips (p < 0.001). Dysplastic hips with coxa profunda had a more anteverted acetabulum (p < 0.001) and inwardly rotated innominate bone (p < 0.002) compared with those without coxa profunda, whereas the acetabular coverage and depth did not differ between the two groups, with the numbers available.

Conclusions

Radiographic coxa profunda was not a sign of increased acetabular coverage and depth in patients with hip dysplasia, but rather indicates classic acetabular dysplasia, defined by an anteverted acetabulum with anterolateral acetabular deficiency and an inwardly rotated pelvis. Thus, the presence of coxa profunda does not indicate a disease in addition to hip dysplasia, and the conventional maneuvers during periacetabular osteotomy are adequate for these patients.

Level of Evidence

Level IV, diagnostic study.     

An Upgrade of the International Hip Dysplasia Institute Classification for Developmental Dysplasia of the Hip

BackgroundThe purpose of the current study was to upgrade the International Hip Dysplasia Institute (IHDI) classification of developmental dysplasia of the hip (DDH).MethodsThe upgrading was suggested by adding the state of the acetabulum (type A for the normal acetabulum and type B for the dysplastic one). The pelvic radiographic films of 110 children suspected to have DDH were used by three observers to sort out the hips into grades according to the original form and the suggested upgraded one subsequently.ResultsThe interobserver reliability between the observers improved from a good level (intraclass correlation coefficient [ICC], 0.885; 95% confidence interval [CI], 0.856–0.909) with the original form to an excellent level (ICC, 0.919; 95% CI, 0.898–0.936) with the upgraded form. When the upgraded form was used, only the grade 1 hips were divided into types A and B, while those classified as grades 2, 3, and 4 were all graded as type B only.ConclusionsThe IHDI classification of DDH can be upgraded into grade 1A, grade 1B, grade 2, grade 3, and grade 4.     

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

PurposeThis 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.MethodsA 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.ResultsThe 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).ConclusionThe 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 evidenceIII - retrospective comparative study     

Are Normal Hips Being Labeled as Pathologic? A CT-based Method for Defining Normal Acetabular Coverage

BackgroundPlain radiographic measures of the acetabulum may fail to accurately define coverage or pathomorphology such as impingement or dysplasia. CT scans might provide more precise measurements for overcoverage and undercoverage. However, a well-defined method for such CT-based measurements and normative data regarding CT-based acetabular coverage is lacking.Questions/purposesThe purposes of the study were (1) to develop a method for evaluation of percent coverage of the femoral head by the acetabulum; and (2) to define normative data using a cohort of asymptomatic patient hip and pelvic CT scans and evaluate the variability in acetabular version for asymptomatic patients with normal lateral coverage (lateral center-edge angle [LCEA] 20°–40°) that has previously been defined as abnormal based on radiographic parameters.MethodsTwo-hundred thirty-seven patients (474 hips) with hip CT scans obtained for reasons other than hip-related pain were evaluated. The scans were obtained from a hospital database of patients who underwent CT evaluation of abdominal trauma or pain. In addition, hips with obvious dysplasia (LCEA < 20°) or profunda (LCE > 40°) were excluded resulting in a final cohort of 222 patients (409 hips [115 men, 107 women]) with CT scans and a mean age of 25 ± 3 years. CT scan alignment was corrected along the horizontal and vertical axis and percent acetabular coverage around the clockface (3 o’clock = anterior), and regional (anterior, superior, posterior) and global surface area coverage was determined. Percent coverage laterally was correlated with the LCEA and the presence and prevalence of cranial retroversion (crossover sign) and a positive posterior wall sign were determined.ResultsThe mean regional percent femoral head surface area coverage for the asymptomatic cohort was 40% ± 2% anteriorly, 61% ± 3% superiorly, and 48% ± 3% posteriorly. Mean global coverage of the femoral head was 40% ± 2%. The local coverage anteriorly (3 o’clock) was 38% ± 3%, laterally (12 o’clock) was 67% ± 2%, and posteriorly (9 o’clock) was 52% ± 3%. The mean lateral coverage represented a mean LCEA of 31° (± 1 SD). Fifteen percent of hips demonstrated cranial retroversion that would correlate with a crossover sign, and 30% had < 50% posterior coverage that would correlate with a positive posterior wall sign on an anteroposterior pelvis radiograph. In addition, male hips had a higher prevalence of a crossover sign (19%; 95% confidence interval [CI], 14%–25% versus 11%; 95% CI, 7%–16%; p = 0.03) and posterior wall sign (46%; 95% CI. 39%–53% versus 13%; 95% CI, 9%–19%; p < 0.001) compared with women. A positive crossover sign or posterior wall sign was present for 113 male hips (53%; 95% CI, 46%–60%) compared with 39 female hips (20%; 95% CI, 15%–26%; p < 0.001).ConclusionsThis study provides normative coverage data and a reproducible method for evaluating acetabular coverage. Cranial acetabular retroversion (crossover sign) and a positive posterior wall sign were frequent findings in a young asymptomatic cohort and might be a normal variant rather than pathologic in a significant number of cases.

Level of Evidence

Level III, diagnostic study.     

Mid‐ to Long‐term Follow‐up of Severe Acetabular Bone Defect after Revision Total Hip Arthroplasty Using Impaction Bone Grafting and Metal Mesh

ObjectiveIn revision total hip arthroplasty (THA), reconstruction of severe acetabular bone defect continues to be problematic for orthopedic surgeons. This study reports the mid‐ to long‐term survivorship, radiological outcomes, and complications of impaction bone grafting (IBG) and metal mesh with a cemented acetabular component in the reconstruction of severe acetabular bone defects in revision THA.MethodsThis retrospective consecutive study included 26 patients (29 hips: type II B, four; type II C, three; type III A, 10; and type III B, 12) who underwent revision THA, which was performed using IBG and metal mesh, between 2007 and 2014 in our institution. All patients were followed up regularly for clinical and radiographical assessments. Migration and loosening of prosthesis graft integration and complications were observed and analyzed. Survival analysis was performed using a Kaplan–Meier survival analysis.ResultsAt the time of revision, 75.9% of the hips (22 hips) were classified as type III bone defects. The average follow‐up period was 9.4 ± 2.8 (range, 2.4–14.0) years. Of the 29 hips, four hips (13.8%) were assessed as clinical failures; at the last follow‐up, two had undergone re‐revision THA, and two had not been scheduled for re‐revision THA despite radiological failure of the acetabular component. Among them, three clinical failures (10.3%) were due to aseptic loosening, and one (3.4%) was due to infection. Radiographic evaluation showed bone graft integration in all hips during the follow‐up. The Kaplan–Meier survivorship analysis revealed an acetabular reconstruction survival rate of 86.5% (95% confidence interval, 61.4%–95.7%) at 10 years.ConclusionIBG and metal mesh with a cemented acetabular component for revision THA is an effective technique for treating severe acetabular bone defects, with effective mid‐ to long‐term outcomes due to the solid reconstruction of the acetabular bone defect and restoration of the hip rotation center.     

Eccentric Rotational Acetabular Osteotomy Using Computed Navigation Guidance for Developmental Dysplasia of the Hip,Sacroiliac Fusion,and Femoroacetabular Impingement Owing to Acetabular Retroversion: A Case Report

BackgroundDevelopmental dysplasia of the hip (DDH) is the main factor that causes secondary osteoarthritis of the hip (hip OA). Acetabular retroversion results in pincer‐type femoroacetabular impingement (FAI), and this is also known to cause secondary hip OA. However, few cases of DDH with acetabular retroversion have been reported, and there is no definite opinion on the optimal treatment. We report a rare case of DDH and FAI owing to acetabular retroversion and dysostosis of the sacroiliac joint that was treated with eccentric acetabular rotational osteotomy (ERAO) using navigation guidance.Case PresentationA 27‐year‐old woman presented with DDH and acetabular retroversion with FAI and dysostosis of the sacroiliac joint on the contralateral side. We performed ERAO using computed navigation guidance and improved the coverage and retroversion of the acetabulum. The acetabular anteversion angle improved from 1° retroversion to 9° anteversion after surgery, the center edge angle improved from 18° to 43°, and the acetabular head index improved from 69% to 93%. The cam lesion of the femur was resected. The Harris Hip Score improved from 55.7 to 100 points at the final examination 2 years after surgery.ConclusionsIn this rare case of DDH and FAI, ERAO using computed navigation guidance accurately improved the coverage and retroversion of the acetabulum.     

There is No Link Between Birth Weight and Developmental Dysplasia of the Hip

AimsDevelopmental Dysplasia of the Hip (DDH) has been linked to high birth weight and packaging disorders, though the evidence is limited. This has implications on screening strategies. The aim of this study was to establish whether birth weight was truly associated with the incidence of DDH.Patients and MethodsThis cohort study analysed the birth weights of all babies born at our institution over a 24 month period, between 01/01/2017 and 01/01/2019. Babies with DDH and those without DDH were compared. Babies were excluded if born before 38 weeks, had incomplete data or were a non-singleton pregnancy. Sub-analysis was performed for DDH severity (dysplastic versus subluxed/dislocated hips), breech presentation, gestational age, gender and ethnicity. Statistical analysis was performed using SPSS.ResultsThere were 10,113 babies born at our institution during the selected timeframe, of which 884 were excluded for prematurity, 336 for being non-singleton and 19 for incomplete data. This left 8874 for analysis, of which 95 babies had confirmed DDH. Both the Non-DDH and DDH data sets had normal distribution (Shapiro-Wilkes, p = 0.308 and 0.629, respectively), with mean birth weights of 3477.7 g with DDH and 3492.8 g without DDH. No difference in birth weight was found (Independent T test, p = 0.789). Females had a lower birth weight than males (3293.1 g versus 3416.6 g (p < 0.001)) yet have a higher incidence of DDH (ratio 6:1 in this dataset). No significant difference was found between birth weights of females with and without DDH (p = 0.068), nor between males with and without DDH (p = 0.513). There were no significant differences in birth weights even when only displaced hips were analysed (p = 0.543), nor according to breech presentation (p = 0.8). Longer gestation babies weighed more (p < 0.00001), yet showed no increase in DDH incidence (p = 0.64).ConclusionThis study discredits the belief that DDH may be related to higher birth weight, thus casting doubt on the link to DDH being a packaging problem in utero. This, therefore, allows future research to prioritise the investigation of alternative aetiologies.     

A modified surgical approach of the hip in children: is it safe and reliable in patients with developmental hip dysplasia?

PurposeTreatment is easier and complications are less likely to occur if developmental dysplasia of the hip (DDH) is diagnosed early. In this study, we examined the early results of open reduction using a medial approach which we had modified for DDH and analyzed the success of this technique and the associated complication rates, with a focus on avascular necrosis (AVN).Methods This is an Institutional Review Board-approved retrospective review of all patients diagnosed with DDH and treated with a modified medial approach at a single institution from July 1999 to December 2010. The patients'' charts were analyzed for clinical and radiographic features.Results Fifty-five hips of 41 patients, all of whom were treated by open reduction using a modified medial approach due to DDH, were evaluated retrospectively. The mean age of the patients at surgery was 19 (range 11–28) months, and the average follow-up was 5.5 (range 3–9.5) years. AVN was the most important complication in terms of radiological outcomes as assessed according to the Kalamchi–McEwen classification. Radiologic results were excellent or good in 51 hips (92.7 %) and fair–plus in four (7.3 %). Type 1 temporary AVN was detected in only two hips (3.6 %), and the lesions had disappeared completely in the final control graphs of these two patients. A secondary intervention was needed for two hips (3.6 %) of the same patients who were operated on due to bilateral DDH. No other complications, such as infection, re-dislocation, or subluxation, were seen in the operated patients.Conclusions We believe that treatment for DDH using a modified medial approach during early childhood is an effective and reliable method with low AVN rates. As shown here, this method achieves great success in radiological and clinical outcomes after a minimum 3-year follow-up.     

Impaction Bone Grafting with Low Dose Irradiated Freeze‐Dried Allograft Bone for Acetabular Reconstruction

ObjectiveReconstruction of acetabular defects has been extremely challenging in both primary and revision total hip arthroplasty (THA). Impaction bone grafting (IBG) can restore the acetabulum bone mass and anatomically reconstruct the acetabulum. Our study aimed to report the short and medium‐term clinical and radiographic outcomes of IBG for acetabular reconstruction in the cemented THA in the Chinese population.MethodsThis was a single‐center retrospective review enrolling 57 patients between May 2013 and July 2019. The patients with acetabular defects were treated with IBG, using low dose irradiated freeze‐dried allograft bone with or without autograft bone, in the cemented THA performed by one senior surgeon. Harris hip score (HHS), standard pelvis anterior–posterior radiograph and lateral hip radiograph were obtained before operation and at 1 week, 3 months, 12 months, and yearly. Graft osteointegration was evaluated by Oswestry''s criteria, and complication was documented at the last follow‐up. Independent sample ANOVA test and Pearson chi‐square tests are used for statistical analysis.ResultsThere were 61 hips in 57 patients. The average follow‐up time was 35.59 months (5–77 months). According to AAOS classification, a total of 18 hips were identified as segmental bone deficiency (type I), with 21 and 22 hips for cavitary bone deficiency (type II) and the combined bone deficiency (type III), respectively. The average HHS was improved from 44.49 (range: 32–58) preoperatively to 86.98 (range: 78–93) postoperatively. Graft osteointegration was satisfactory (Oswestry score ≥2) in all patients. No dislocation occurred in the 57 patients (61 hips) during follow‐up. Although one cup migrated, no revision, re‐revision, radiographic loosening, graft bone lysis, or postoperative complications were detected at the final follow‐up.ConclusionsIBG with low‐dose irradiated freeze‐dried allograft bone in acetabular bone defect reconstruction is a reliable technique for restoring acetabular bone defects in THA.     

Restoring Rotation Center in Total Hip Arthroplasty for Developmental Dysplasia of the Hip with the Assistance of Three Dimensional Printing Technology: A Pilot Study

ObjectiveTo develop a new method to restore hip rotation center exactly and rapidly in total hip arthroplasty (THA) with the assistance of three dimensional (3D) printing technology and evaluate its clinical and radiological outcomes.MethodsFrom March 2014 to July 2018, a total of 17 patients (five hips of four men and 16 hips of 13 women) with end‐stage osteoarthritis secondary to developmental dysplasia of the hip who underwent THA were analyzed and followed up retrospectively. The average age is 58.00 ± 8.12 years (range from 45 to 71 years). Simulated operations were performed on 3D printed hip models for preoperative planning. The morphology of Harris fossa and acetabular notches were recognized and restored to locate the acetabular center. The size of bone defect was measured by the bone wax method. The agreement on the size of acetabular cup and bone defect between simulated operations and actual operations were analyzed. Harris Hip Score (HHS) was used to evaluate the recovery of hip joint function. The vertical distance and horizontal distance of the rotation center on the pelvis plain radiograph were measured, which were used to assess the efficacy of restoring hip rotation center and acetabular cup migration.ResultsThe mean sizes of bone defect in simulated operations and THA were 4.58 ± 2.47 cm² and 4.55 ± 2.57 cm² respectively. There was no significant difference statistically between the sizes of bone defect in simulated operations and the actual sizes of bone defect in THA (t = 0.03, P = 0.97). The sizes of the acetabular cup of simulated operations on 3D print models showed a high rate of coincidence with the actual sizes in the operations (ICC = 0.93). All 17 patients were available for clinical and radiological follow‐up. The average follow‐up time was 18.35 ± 6.86 months (range, 12–36 months. The average HHS of the patients was improved from (38.33 ± 6.07) preoperatively to the last follow‐up (88.61 ± 3.44) postoperatively. The mean vertical and horizontal distances of hip rotation center on the pelvic radiographs were restored to 15.12 ± 1.25 mm and 32.49 ± 2.83 mm respectively. No case presented dislocation or radiological signs of loosening until last follow‐up.ConclusionsThe application of 3D printing technology facilitates orthopedists to recognize the morphology of Harris fossa and acetabular notches, locate the acetabular center and restore the hip rotation center rapidly and accurately.     

Residual Acetabular Dysplasia in the Reduced Hip

BackgroundResidual 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).DiscussionAge 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.ConclusionRAD 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.     

Is Obesity Associated with Higher Complication Rates in Total Hip Arthroplasty for High-Riding Dysplastic Hips?

ObjectiveDevelopmental dysplasia of the hip (DDH) is a disabling pathology leading to hip problems, such as painful arthritic hip, unstable hip, etc. Total hip arthroplasty (THA) is an effective treatment modality for this condition. Obesity has been shown to be associated with increased rates of complications following orthopaedic surgeries (Journal of Arthroplasty 20:46–50). The hypothesis of this study was that patients with a body mass index (BMI) greater than 30 (obese), who undergo total hip arthroplasty for dysplastic hip, are associated with longer operative and anaesthetic times, longer hospital stays and higher re-admission rates within 30 days.MethodsAll the cases of total hip arthroplasty in patients with high-riding dysplastic hips were reviewed. Evaluation was made of a total of 68 patients comprising 64 females and 4 males, classified into two groups. Patients with BMI < 30 kg/m² formed the non-obese group and patients with BMI ≥ 30 kg/m² the obese group.ResultsThe mean age was 44.67 ± 6.49 years. BMI was < 30 in 44 (64.7%) patients and > 30 in 24 (35.3%) patients. The data analysis showed that mean surgical time, anaesthesia duration and re-admission rate were significantly higher in the group with BMI ≥ 30(obese) as compared to the group with BMI < 30 (non-obese) (p < 0.01). The complication rate was determined to be higher in the obese group (p < 0.05).ConclusionObese patients performed with total hip arthroplasty for high-riding dysplastic hips had more complications and higher rates of re-admission to hospital compared with the non-obese patients.     

How Are Dysplastic Hips Different? A Three-dimensional CT Study

Background

Surgical correction of acetabular dysplasia can postpone or prevent joint degeneration. The specific abnormalities that make up the dysplastic hip are controversial.

Questions/purposes

(1) What are the relative size, shape, and orientations of the typical nondysplastic hip? (2) How do these variables differ in the developmentally dysplastic hip? (3) Are there version differences between the acetabuli of dysplastic and nondysplastic hips? (4) Are there pairs of variables in which the change in one is always accompanied by a change in the other for both nondysplastic and dysplastic acetabuli?

Methods

Of 117 consecutive three-dimensional (3-D) CT scans performed for hip dysplasia between March 1988 and October 1995, 48 met criteria of developmentally dysplastic hips by plain radiography. These were retrospectively compared with 55 pelvic 3-D CT scans culled from 81 consecutive scans performed for reasons other than hip dysplasia (ie, hip pain, trauma, infection) that did not affect the hip or pelvic landmarks. The 3-D reconstructions were orientated anatomically for standardization of the measurements to be compared. Representative 3-D volumes of the acetabular space were constructed from which we could measure anatomic positions and dimensional information. One author performed all image orientation and measurements.

Results

Nondysplastic acetabuli are essentially hemispheric with height equal to width and twice the depth. The dysplastic acetabuli were elongated in females (52.4 ± 6.2 mm for dysplastic versus 46.5 ± 4.6 mm for nondysplastic (mean difference, 5.0; 95% confidence interval [CI], 1.9–8.0; p = 0.002) and shallower in both females (18.7 ± 4.9 mm for dysplastic versus 23.6 ± 4.0 mm for nondysplastic; mean difference, 6.5; 95% CI, 4.4–8.5; p < 0.0001) and males (21.1 ± 4.8 mm for dysplastic versus 25.0 ± 4.3 mm for nondysplastic, mean difference, 5.3; 95% CI, 2.6–8.1; p = 0.0002); width was similar to that of nondysplastic hips. Acetabular openings were slightly more vertical than nondysplastic hips in females (5°; 95% CI, 1.9–8.1; p = 0.002) but not in male subjects. The dysplastic acetabuli were smaller in volume (18% in females, p = 0.002, and 19% in males, p = 0.0012) and had less space occupied by the femoral head compared with nondysplastic hips (p < 0.0001 for females, p < 0.0001 for males). Dysplastic hip midacetabulum was 4° more anteverted in females (95% CI, 0.5–6.8; p = 0.022) but not for males (p = 0.538). The upper dysplastic acetabulum was more retroverted in females and males (10.2°; 95% CI, 5.5–15; p < 0.0001, and 7.0°; 95% CI, 0.6–13.4; p = 0.032, respectively). Acetabular volumes in nondysplastic and dysplastic hips were related to acetabular width but not to length.

Conclusions

Developmentally dysplastic acetabuli are not deficient in merely a single dimension but are globally deficient. The subluxated femoral head lies in the elongated and retroverted superior acetabulum, which becomes progressively shallower as the acetabulum increases in length. Focally deficient anterior or posterior femoral head coverage is uncommon. Current procedures that redirect the acetabulum, no matter how technically successful, cannot fully compensate for the incongruence of a spherical femoral head within a shallow and elongated acetabulum unless corrected at an early age when acetabular remodeling is possible. Early detection and treatment of acetabular dysplasia should be emphasized.

Level of Evidence

Level III, prognostic study.     

Analysis of Factors Affecting Early Functional Recovery of Bernese Periacetabular Osteotomy

ObjectivesTo explore factors affecting the efficacy of Bernese periacetabular osteotomy for the treatment of hip dysplasia.MethodsA retrospective study was conducted on 44 patients with hip dysplasia who underwent Bernese periacetabular osteotomy with a modified Smith‐Peterson approach between January 2017 and November 2019. Among them, 40 were women and four were men. The average age was 31.2 ± 9.4. Preoperative and postoperative imaging parameters were measured. The acetabular top tilt angle, lateral central edge angle, acetabular abduction angle, femoral head extrusion index, sphericity index of femoral head, Shenton line, Tonnis grade of osteoarthritis, joint congruency, p/a ratio, acetabular anteversion angle, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale scores, and modified Harris hip score (MHHS) were observed. MHHS were divided into three clinically relevant categories: poor (<70 points), good (70–85 points), and excellent (86–91 points). Patient demographic data, as well as preoperative and postoperative radiographic parameters, were subjected to univariate logistic regression analysis. Multiple regression analysis was used to determine factors influencing postoperative MHHS.ResultsThe follow‐up time was 1.0–3.9 years after surgery, with an average of 1.6 years. By the last follow‐up, MHHS increased from 70 points before surgery to 91 points after surgery (P < 0.001), WOMAC pain score decreased from 4 points before surgery to 0 points after surgery (P < 0.001). WOMAC functional score decreased (Preoperative: 18.0 [4.0]; Postoperative: 4.0 [0], P = 0.004). Six patients had sensory disturbance of the lateral femoral cutaneous nerve, four of which recovered completely during follow‐up. No other complications related to surgical approach, osteotomy, acetabular displacement, acetabular fixation, and postoperative stage were found. There was no significant vascular, nerve, or visceral injuries in any of the patients. On multiple regression analysis, the probability of the postoperative modified Harris hip score of a hip joint with a preoperative lateral center edge angle ≥4.5° being classified as excellent was six times that of angles <4.5° (Exp[β]: 6.249, 95% CI: 1.03–37.85, P = 0.046). Regression analysis of other factors found no significant correlation with postoperative functional scores.ConclusionOverall functional scores post‐PAO significantly improved, and pain symptoms were significantly reduced. Patients with a preoperative lateral center edge angle ≥4.5° had better joint function after surgery.     

Borderline Developmental Dysplasia of the Hip: A Risk Factor Predicting the Development and Poor Prognosis after Core Decompression for Idiopathic Osteonecrosis of the Femoral Head

ObjectiveIt is unclear whether idiopathic osteonecrosis of the femoral head (ONFH) is associated with borderline developmental dysplasia of the hip (BDDH). This study aimed to compare the incidence of BDDH between patients with idiopathic ONFH and matched control subjects and determine the influence of BDDH on poor prognosis after core decompression (CD).MethodsWe retrospectively examined 78 consecutive patients (111 hips) with idiopathic ONFH undergoing CD and 1:2 matched with 156 control subjects (222 hips). The anteroposterior pelvic radiographs were used to measure the acetabular anatomical parameters and divide included subjects into BDDH or non‐BDDH group. The incidence of BDDH and acetabular anatomical parameters were compared between patients with idiopathic ONFH and matched controls. Clinical outcomes, such as Harris Hip Score (HHS), progression of collapse, and conversion to total hip arthroplasty (THA), were compared between patients with BDDH and without BDDH in the idiopathic ONFH group, with a mean follow‐up of 72.1 ± 36.6 months.ResultsPatients with idiopathic ONFH had a significantly higher incidence of BDDH than matched controls (29.7% vs 12.2%, p < 0.001). Less acetabular coverage was also found in patients with idiopathic ONFH than in matched controls as demonstrated by lower CEA (28.5° ± 4.7° vs 33.1° ± 5.7°, p < 0.001), AHI (82.4 ± 5.0 vs 86.3 ± 5.4, p < 0.001), ADR (299.6 ± 28.4 vs 318.8 ± 31.3, p < 0.001), and a higher sharp angle (40.0° ± 3.4° vs 37.4° ± 3.7°, p < 0.001). In patients with idiopathic ONFH, the BDDH group had a significantly lower mean HHS at the last follow‐up (83.5 ± 17.4 vs 91.6 ± 9.7, p = 0.015) with a different score distribution (p = 0.004), and a lower 5‐year survival rate with both clinical failure (66.7%, 95% CI 52.4%–84.9% vs 83.7%, 95% CI 75.2%–93.1%; p = 0.028) and conversion to THA (74.6%, 95% CI 60.7%–91.6% vs 92.1%, 95% CI 85.6%–99.0%; p = 0.008) as the endpoints than the non‐BDDH group.ConclusionThe incidence of BDDH was significantly higher in patients with idiopathic ONFH than matched controls, and idiopathic ONFH patients who underwent CD with BDDH had lower mean HHS as well as 5‐year survival rate than those without BDDH. Therefore, BDDH should be considered a risk factor predicting the development of idiopathic ONFH as well as poor prognosis after CD.