Abduction Orthosis in Treatment of Primary Acetabular Dysplasia: Results of Three Years Follow-up

This study aims to evaluate the effectiveness of full-time bracing in residual acetabular dysplasia (RAD) and the effect of previous Pavlik harness usage on the results of treatment with abduction orthosis. We retrospectively reviewed 80 patients (9 males, 71 females; mean age 6±0.8 months; range, 5 to 7 months) with developmental dysplasia of the hip (119 dysplastic hips) treated with hip abduction orthosis. Patients with an acetabular index (AI) measurement of 30° and over who used full-time hip abduction brace for six months were included in the study. Acetabular index values were measured at the initiation, third, and sixth months of treatment and the effectiveness of abduction orthosis was evaluated. The patients were analyzed for the effect of prior Pavlik harness application on abduction orthosis treatment. Mean AI value of the dysplastic hips (n=119) was 33.4°±2.6°, which decreased to 28.5°±2.6° after treatment (p<0.001). The AI improvement in the first three-month period was significantly faster than the second three-month period (2.9°±1.9° vs. 1.9°±1°; p=0.013). No difference was observed in AI development between patients with or without prior Pavlik treatment (p=0.1). In patients with unilateral dysplasia, dysplastic hips improved significantly faster than normal hips (p<0.001). As a result of a mean follow-up duration of 20.2±9.8 months from the onset of brace treatment, 32 (32%) hips were grouped as normal, 49 (48%) as mildly dysplastic, and 22 (20%) as severely dysplastic based on Tönnis criteria. Hip abduction orthosis may be used in patients with RAD between 6 to 12 months of age. Acetabular index improvement was faster in the first three months of brace treatment. Dysplastic hips improved faster than normal hips, and prior Pavlik harness treatment did not alter the effectiveness of orthosis.

Surgical correction of acetabular dysplasia can postpone or prevent joint degeneration. The specific abnormalities that make up the dysplastic hip are controversial. (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? 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. 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. 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 III, prognostic study.

To utilise machine learning, unsupervised clustering and multivariate modelling in order to predict severe early joint space narrowing (JSN) from anatomical hip parameters while identifying factors related to joint space width (JSW) in dysplastic and non-dysplastic hips. A total of 507 hip CT examinations of patients 20-55 years old were retrospectively examined, and JSW, center-edge (CE) angle, alpha angle, anterior acetabular sector angle (AASA), and neck-shaft angle (NSA) were recorded. Dysplasia and severe JSN were defined with CE angle < 25o and JSW< 2 mm, respectively. A random forest classifier was developed to predict severe JSN based on anatomical and demographical data. Multivariate linear regression and two-step unsupervised clustering were performed to identify factors linked to JSW. In dysplastic hips, lateral or anterior undercoverage alone was not correlated to JSN. AASA (p < 0.005) and CE angle (p < 0.032) were the only factors significantly correlated with JSN in dysplastic hips. In non-dysplastic hips, JSW was inversely correlated to CE angle, AASA, and age and positively correlated to NSA (p < 0.001). A random forest classifier predicted severe JSN (AUC 69.9%, 95%CI 47.9-91.8%). TwoStep cluster modelling identified two distinct patient clusters one with low and one with normal JSW and different anatomical characteristics. Machine learning predicted severe JSN and identified population characteristics related to normal and abnormal joint space width. Dysplasia in one plane was found to be insufficient to cause JSN, highlighting the need for hip anatomy assessment on multiple planes. • Neither anterior nor lateral acetabular dysplasia was sufficient to independently reduce joint space width in a multivariate linear regression model of dysplastic hips. • A random forest classifier was developed based on measurements and demographic parameters from 507 hip joints, achieving an area under the curve of 69.9% in the external validation set, in predicting severe joint space narrowing based on anatomical hip parameters and age. • Unsupervised TwoStep cluster analysis revealed two distinct population groups, one with low and one with normal joint space width, characterised by differences in hip morphology.

Background:Hip dysplasia has been shown to be a cause of early arthritis. The decrease in bony coverage has shown increased stress on the acetabular labrum as it shares an increased load.Purpose/Hypothesis:The purpose of this study was to divide a cohort of patients by radiographic measures of dysplastic and nondysplastic hips for comparison with regard to labral size at 4 anatomic locations. The hypothesis was that dysplastic hips will have significantly larger labral size compared with nondysplastic hips.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A prospective study was conducted at a single institution. A total of 130 patients underwent hip arthroscopy during the study period from September 2011 to February 2012. Intraoperatively, arthroscopic measurements were taken at 4 quadrants on the acetabular clockface: anterosuperior (12-3 o’clock), anteroinferior (3-6 o’clock), posterosuperior (9-12 o’clock), and posteroinferior (6-9 o’clock). Three radiographic parameters for dysplasia were used to substratify the study population base: lateral center-edge angle (LCEA) ≤25° and LCEA >25°, acetabular inclination (AI) ≤10° and AI >10°, and anterior center-edge angle (ACEA) ≤20° and ACEA >20°.Results:For the LCEA ≤25° group, there were 28 hips with mean LCEA of 20.96° ± 3.40°. Patients with LCEA ≤25° had larger labral width in all 4 quadrants (P < .05). For AI >10°, there were 12 hips with the mean AI 12.92° ± 2.50°. Patients with AI >10° had larger labral size in the posteroinferior quadrant only (P < .05). For ACEA ≤20°, there were 4 hips with a mean ACEA of 11.25° ± 5.19°. The anteroinferior and posteroinferior quadrants had a significant increase in labral size when substratified by ACEA ≤20° (P < .05).Conclusion:Labral size was significantly larger in dysplastic hips compared with nondysplastic hips. The posteroinferior quadrant labrum was larger in size in dysplastic hips, as measured by any of the 3 radiographic measurements of dysplasia. Hips with LCEA ≤25° had larger labra in all 4 quadrants.

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.

ACR Appropriateness Criteria® on Developmental Dysplasia of the Hip—Child

Assessment of 3-dimensional (3D) femoral head coverage is critical in evaluating, preoperative planning, and treating hip dysplasia. To (1) propose a mathematical model to establish 3D femoral head coverage using conventional computed tomography (CT), (2) determine the correlation of 2D parameters with 3D coverage, and (3) characterize the patterns of dysplasia based on 3D morphology. Cross-sectional study; Level of evidence, 3. We identified 30 patients (n = hips) with symptomatic dysplasia and 30 patients (n = hips) without dysplasia. Patients with dysplastic hips were matched with regard to sex, age, and body mass index to those with nondysplastic hips. Preoperative CTs were analyzed using 3D software, and 3D femoral head surface area coverage (FHSAC; in %) was assessed in 4 quadrant zones: anteromedial, anterolateral, posteromedial, and posterolateral. To assess lateral coverage of the femoral head, we introduced the anterolateral femoral head coverage angle (ALFC) and the posterolateral femoral head coverage angle (PLFC). Reduced femoral head coverage was more pronounced in dysplastic versus nondysplastic hips in the anterolateral quadrant (18% vs 40.7%, respectively) and posterolateral quadrant (35.8% vs 56.9%, respectively) (P < .0001 for both). Dysplastic hips had smaller ALFC and PLFC (18.4° vs 38.7°; P < .0001; 47.2° vs 72.3°; P = .0002). Anterolateral and posterolateral FHSAC were strongly correlated with the ALFC (r = 0.88; P < .0001) and the PLFC (r = 0.82; P < .0001) along with the lateral center-edge angle (anterolateral, r = 0.75; P < .0001; posterolateral, r = 0.73; P < .0001). Prediction models established for FHSAC had strong agreement with explanatory CT variables (anterolateral: r = 0.91; P < .0001; posterolateral: r = 0.90; P < .0001). The cutoff values for anterolateral and posterolateral FHSAC were 25% and 41%, respectively. In dysplastic hips, global deficiency was most common (15/30 hips), 9 hips showed an anterolateral deficiency, and 4 hips had a posterolateral deficiency pattern. The ALFC and The PLFC were strongly correlated with 3D lateral FHSAC and were able to predict 3D coverage accurately.

Patient-specific analysis of cartilage and labrum mechanics in human hips with acetabular dysplasia

Evaluation of translation in the normal and dysplastic hip using three-dimensional magnetic resonance imaging and voxel-based registration

In the setting of acetabular dysplasia, the increased translational motion of the femur may damage the labrum and cartilage, as well as stretch the capsule. The purpose of the study was to investigate the relationship between the acetabular coverage and the capsular stiffness by assessing the distension of anterior and posterior joint recesses on the hip computed tomography arthrography. One hundred thirty-three patients (138 hips) with a median age of 36years (range 18-50years) who received the computed tomography arthrography for evaluation of nonarthritic hip pain in our institute between 2015 and 2017 were retrospectively reviewed. The maximal distance between the anterior/posterior capsule and the anterior femoral head-neck junction/posterior femoral head on the axial imaging of computed tomography arthrography was defined as the width of anterior/posterior joint recess. The width of anterior/posterior joint recess was adjusted with the diameter of the femoral head and was then compared between acetabular dysplasia (lateral center-edge angle < 25°), normal acetabulum (lateral center-edge angle between 25 and 39°), and deep acetabulum (lateral center-edge angle > 39°). In addition, the standard univariate linear regression analysis was used to investigate the relationship between the adjusted width of anterior/posterior joint recess and anterior/posterior coverage of the hip, determined by the anterior/posterior wall index. The adjusted width of posterior joint recess was significantly greater in the acetabular dysplasia group than the normal acetabulum and deep acetabulum groups (p < 0.01 and p = 0.02, respectively). There was no significant difference of the adjusted width of anterior joint recess between the groups (n.s.). The adjusted width of posterior joint recess had a significant but weak negative correlation with the anterior wall index (r = - 0.25, p < 0.001), and no correlation with the posterior wall index (r = - 0.0004, n.s.). There was no significant correlation between the adjusted width of anterior joint recess and the anterior/posterior wall index (r = 0.05, n.s./r = 0.07, n.s.). The distension of posterior capsule on the computed tomography arthrography was significantly greater in acetabular dysplasia. In addition, there was a significant but weak negative correlation between the distension of posterior capsule and the anterior coverage of the hip. It indicated a looser posterior capsule was observed in a dysplastic hip. The relevance of posterior capsular laxity to clinical outcomes warrants further investigation. Given the fact that the distension of anterior capsule was not significantly higher in acetabular dysplasia, the need of anterior capsular plication in a dysplastic hip should be carefully evaluated. Level III.

To evaluate the evolution of the ultrasonographic pubo-femoral distance (PFD) before and after Pavlik harness treatment for developmental dysplasia of the hip (DDH) in newborns. Twenty-five patients (16.7±10.4days; 19 females, six males) diagnosed with DDH and treated using the Pavlik harness were included. Eighteen patients had bilateral, and seven unilateral DDH, with a total of 43 dysplastic hips. The seven non-dysplastic hips in unilateral cases were used for comparison. The PFD was measured in the coronal and axial planes with the hip flexed to approximately 90°, before and after an average of 93days of treatment. The femoral head coverage was assessed in the coronal plane, and correlated with PFD values. In dysplastic hips, the mean PFD decreased from 6.1±1.8mm to 3.0±0.7mm in the axial (adjusted difference, 2.9mm; p<0.01), and from 5.9±2.0 to 3.0±0.6mm in the coronal plane (adjusted difference 2.7mm; p<0.01). The femoral head coverage increased from 30.8 to 62.1%, and the mean differences of femoral head coverage and PFD were significantly correlated (p<0.001). There was no difference between treated dysplastic and non-dysplastic hips. There was high intra- and inter-observer agreement for PFD measurements. The PFD decreased significantly after DDH treatment using the Pavlik harness in newborns, and showed significant correlation with the femoral head coverage improvement. PFD might be a reliable tool for monitoring DDH treatment in newborns treated using the Pavlik harness.

ObjectivesTo determine whether acetabular dysplasia is associated with hip pain at physical examination among adults with recent-onset inflammatory back pain (IBP) suggesting axial spondyloarthritis (axSpA).MethodsThis cross-sectional ancillary study was conducted on the prospective DESIR cohort, which enrolled patients aged 18–50 years who had recent-onset IBP. Two readers used antero-posterior pelvic radiographs to assess the Tönnis angle, acetabular angle (AA), lateral centre-edge angle (LCEA), and femoral head extrusion index (FHEI). Abnormality of one or more of these four variables defined acetabular dysplasia. Hip pain upon physical examination was assessed based on Ritchie’s articular index.ResultsThe overall prevalence of acetabular dysplasia was 22% (139/636). The proportion of females was higher in the group with acetabular dysplasia. Hip pain was found in 21% (29/139) of patients with versus 12% (59/497) without acetabular dysplasia (OR, 1.96; 95% CI, 1.20 to 3.20); the association was significant in males (OR, 3.14; 95% CI, 1.44 to 6.86) but not females (OR, 1.39; 95% CI, 0.74 to 2.62). Results were similar when acetabular dysplasia was defined on the basis of LCEA alone (OR, 2.15; 95% CI, 1.18 to 2.62).ConclusionAmong patients with recent-onset IBP suggesting axSpA, acetabular dysplasia was significantly associated with hip pain in males. Hip pain related to acetabular dysplasia might result in overdiagnosis of hip involvement by axSpA.

A prospective trial was carried out to assess the outcome of children aged from 2 to 6 weeks with stable but dysplastic hips, treated with abduction splintage or by observation. Forty-four patients with 63 dysplastic hips were entered into the study and allocated into the two treatment groups at random. The ultrasound measured percentage acetabular cover in the splinted group improved in the first 3 months from an average of 32.8 to 54.3%. In the unsplinted group, the increase in cover was from 36.7 to 48.6%. The changes in cover for the splinted group were significantly more than those for the unsplinted group (p < 0.003) There was, however, no significant difference between the two groups in acetabular angle measurements on plain radiographs taken at 3 months. At 24 months, similarly, there was no significant difference in the acetabular angles of the two groups. These results support the view that stable dysplastic hips will correct with growth and that there is no sustained benefit from early splintage.

A prospective trial was carried out to assess the outcome of children aged from 2 to 6 weeks with stable but dysplastic hips, treated with abduction splintage or by observation. Forty-four patients with 63 dysplastic hips were entered into the study and allocated into the two treatment groups at random. The ultrasound measured percentage acetabular cover in the splinted group improved in the first 3 months from an average of 32.8 to 54.3%. In the unsplinted group, the increase in cover was from 36.7 to 48.6%. The changes in cover for the splinted group were significantly more than those for the unsplinted group (p < 0.003) There was, however, no significant difference between the two groups in acetabular angle measurements on plain radiographs taken at 3 months. At 24 months, similarly, there was no significant difference in the acetabular angles of the two groups. These results support the view that stable dysplastic hips will correct with growth and that there is no sustained benefit from early splintage.

The clinical significance of acetabular retroversion in non-dysplastic hips can be explained as pincer-type femoroacetabular impingement (FAI), whereas that in dysplastic hips is not clarified because FAI normally poses little problems for dysplastic hips. We aimed to evaluate three-dimensional (3D) femoral head coverage in dysplastic hips with and without acetabular retroversion and to elucidate the role of acetabular retroversion on the 3D femoral head coverage. We retrospectively investigated 93 hips in 93 patients (9 males and 84 females) that underwent periacetabular osteotomy for hip dysplasia. Dysplastic hips were divided into anteversion and retroversion groups according to their cranial anteversion, which was measured on the axial section 5mm caudal to the acetabular roof. The 3D femoral head coverage was provided as a percentage of the acetabulum-covered surface area of the upper femoral hemisphere using a 3D preoperative planning software for total hip arthroplasty. Of the 93 dysplastic hips, 15 hips (16%) were assignedto the retroversion group, which had significantly younger age at surgery (31.9years versus 39.2years; p = 0.033). The lateral center-edge angles were comparable between the groups (13.8° versus 12.9°; p = 0.68); however, the hips in the retroversion group had a trend of smaller 3D femoral head coverage than those in the anteversion group (59% versus 63%; p = 0.058). Multivariate analysis using two-way analysis of covariance showed that lateral center-edge angle (partial regression coefficient = 0.83; t value = 17.3; p < 0.001) and acetabular retroversion (partial regression coefficient = - 2.3; t value = - 4.9; p < 0.001) were independent factors that contributed to the 3D femoral head coverage. Acetabular retroversion in dysplastic hips was associated with decreased 3D femoral head coverage independently from lateral center-edge angle. The age at surgery in the retroversion group was significantlyyounger, suggesting a relationship between decreased 3D coverage and potentially earlier symptom onset.