High prevalence of acetabular retroversion in both affected and unaffected hips after Legg-Calvé-Perthes disease

Background

Acetabular retroversion is observed in hips after various pediatric hip diseases. This study sought to examine the frequency of acetabular retroversion in both affected and unaffected hips after Legg-Calvé-Perthes disease and its correlation with the prominence of the ischial spine.

Methods

We retrospectively investigated the version and morphological features of the acetabulum using pelvic radiographs after Legg-Calvé-Perthes disease (107 affected hips treated non-operatively and 72 unaffected hips from the contralateral side). The diagnosis of acetabular retroversion was made based on the presence of a positive cross-over sign on anteroposterior pelvic radiographs. The correlation between the presence of a positive cross-over sign and modified Stulberg classes, the onset age of Legg-Calvé-Perthes disease, radiographic parameters for acetabular dysplasia and the prominence of the ischial spine were examined.

Results

The prevalence of a positive cross-over sign was 49.5 % (45 of 91 hips) in affected hips and 45.8 % (33 of 72 hips) in unaffected hips. Hips with a positive cross-over sign were significantly coexistent bilaterally. The prevalence of prominence of the ischial spine in the positive cross-over sign group was 71.4 % in the affected side and 81.8 % in the unaffected side, indicating a significant correlation between the cross-over sign and the prominence of the ischial spine in both affected and unaffected hips. The positive cross-over sign did not have any correlation with the parameters for acetabular dysplasia and the onset age, however, had a significant correlation with the severity of the femoral head deformity.

Conclusions

High prevalence of acetabular retroversion in both affected and unaffected hips after Legg-Calvé-Perthes disease was demonstrated. Symmetric acetabular deformity and the coexistence of prominence of the ischial spine suggested the effects of the Legg-Calvé-Perthes disease lesions on the skeletal development of the whole pelvis. Further follow-up is needed to clarify the pathological significance of acetabular retroversion after Legg-Calvé-Perthes disease.     

Radiological morphology variances of transient osteoporosis of the hip

Background

Although several morphological abnormalities or variances of the hip joint have been proposed to be associated with hip joint degeneration, few studies have investigated any radiological features in patients with transient osteoporosis of the hip (TOH). The purpose of this study is to evaluate the morphological variances of the hip joint in TOH patients radiographically.

Is the Acetabulum Retroverted in Slipped Capital Femoral Epiphysis?

Background

Recent biplanar radiographic studies have demonstrated acetabular retroversion and increased superolateral femoral head coverage in hips with slipped capital femoral epiphysis (SCFE), seemingly divergent from earlier CT-based studies suggesting normal acetabular version.

Question/purposes

We therefore asked: Are there differences in (1) acetabular version at the superior ¼ of the acetabular dome (AV_sup), (2) acetabular version at the center of the femoral head (AV_cen), and (3) superolateral femoral head coverage (lateral center-edge angle [LCEA]) among affected SCFE hips, unaffected hips, and normal controls?

Methods

We identified 32 patients with SCFE who underwent CT between 2007 and 2012. Twenty-three met our inclusion criteria. Seventy-six age- and sex-matched normal patients comprised the control group. Pelvic rotation, tilt, and inclination were corrected on each CT. AV_sup, AV_cen, and LCEA were measured.

Results

The mean AV_sup of the affected hips (−1.71°) demonstrated retroversion compared to the unaffected hips and the control group; the mean AV_sup of the unaffected hips was similar to that of the normal controls. Mean AV_cen was similar among the three groups. The LCEA was higher in affected and unaffected SCFE hips than in the control group (34.3° versus 34.5° versus 28.9°, respectively), but we found no difference between affected and unaffected hips.

Conclusions

Our data suggest an association of superior acetabular retroversion and increased superolateral femoral head coverage in SCFE. Whether this represents a primary abnormal morphology or a secondary pathologic response remains unclear. Further studies investigating the role of acetabular morphology in SCFE and its implications for development of symptomatic femoroacetabular impingement are warranted.     

Remodelling of femoral head–neck junction in slipped capital femoral epiphysis: a multicentre study

Purpose

We examined the remodelling of the femoral head–neck junction in patients with slipped capital femoral epiphysis (SCFE) and the frequency of residual cam deformities.

Methods

We reviewed 69 hips in 56 patients with stable SCFE who had undergone in situ pinning. Mean age at slip was 11.7 years and the follow-up period 63.4 months. Cam deformity was evaluated using the anterior offset alpha (α) angle and head–neck offset ratio (HNOR).

Results

The average α angle and HNOR significantly improved from 76.2° to 51.3° and 0.086 to 0.135, respectively; 25 hips (36.2 %) still had an α angle greater than 50°, and 32 hips (46.4 %) had an HNOR of under 0.145. A multivariate analysis selected age at onset and slip angle as risk factors for cam deformity, with cutoff values 11.1 years and 21.0°, respectively.

Conclusions

Although most hips had remodelling of the head–neck junction, 29.4 % had residual cam deformities that may be susceptible to femoroacetabular impingement.     

Association between body mass index-for-age and slipped capital femoral epiphysis: the long-term risk for subsequent slip in patients followed until physeal closure

Background

Children who present with idiopathic slipped capital femoral epiphysis (SCFE) have an increased risk of developing bilateral disease. Predicting which patients will develop problems with bilateral hips is important for determining treatment algorithms. This is a retrospective observational study that evaluates the relationship and risk between body mass index (BMI)-for-age and unilateral and bilateral SCFE in patients followed until physeal closure.

Methods

This is a retrospective study of all patients with SCFE presenting to one institution from 1998–2005. Using the Center for Disease Control (CDC) references, BMI-for-age was calculated for each patient. The patients were followed up until complete closure of the bilateral proximal femoral physes, which was considered completion of the study. Statistical analysis for significant differences between groups was performed using the Kruskal–Wallis test for equality of populations. A logistic regression, controlling for age and gender, was used to identify BMI-for-age as a risk factor and to determine the significance of the odds ratios (ORs) for the relevant categorical variables—obese, overweight and healthy weight.

Results

Eighty patients (56 male, 24 female) presented to a single institution between 1998 and 2005 with a diagnosis of SCFE. The mean age of patients was 12.2 years at initial presentation (range 8.5–16). Forty-eight patients (32 male, 16 female) presented with unilateral SCFE, with 22 of the 48 patients having a BMI for-age percentile ≥95 %. Thirty-two patients (24 male, 8 female) presented with bilateral SCFE, with 29 of the 32 patients having a BMI-for-age percentile ≥95 %. Patients with a BMI-for-age ≥95 % had a significantly increased risk of presentation with bilateral slips (OR 4.83; relative risk [RR] 3.01; p < 0.05]. All but one patient in this study with bilateral SCFE or unilateral SCFE with subsequent contralateral involvement had a BMI-for-age ≥85 % (44 out of 45 patients). Additionally, the overall risk of developing bilateral SCFE until physeal closure with a BMI-for-age ≥95 % was significantly increased (OR 3.84; RR 2.02; p < 0.05; number needed to treat [NNT] 3.01).

Conclusions

Previous work has established a relationship between BMI and SCFE. The CDC BMI-for-age growth charts more accurately measure obesity in the pediatric population compared to BMI and are therefore a more appropriate reference tool. This study demonstrates an association between obesity measured by BMI-for-age percentiles and SCFE. This study also demonstrates an association between BMI-for-age and risk for bilateral SCFE at presentation as well as overall incidence of developing bilateral SCFE in the obese pediatric population. By defining the at-risk population through BMI-for-age, physicians can screen the pediatric patient population and provide early strategies for therapeutic weight loss which may reduce the incidence of SCFE.

     

Axial plane coverage and torsion measurements in primary osteoarthritis of the hip with good frontal plane coverage and spherical femoral head

Introduction

Mechanical factors play a role in pathogenesis of primary osteoarthritis of the hip. Torsion measures were made to detect whether there is a causal relationship between increase or decrease of femoral anteversion, acetabular anteversion, and osteoarthritis. There are no studies in the literature indicating a relationship between axial plane coverage and osteoarthritis of the hip. Deficient axial plane coverage of femoral head may also play a role in pathogenesis of osteoarthritis.

Materials and methods

Thirty patients with primary osteoarthritis of the hip and 29 control cases were included in the study. We used the method of Anda et al. (Acta Radiol Diagn 27:443–447, 1986; Comput Assist Tomogr 15:115–120, 1991) to measure axial plane anterior, posterior coverages in patients with primary osteoarthritis of the hip. The computerized tomography sections and pelvic radiographs indicated good frontal plane coverage and spherical femoral head. In addition to anterior acetabular sector angle, posterior acetabular sector angle, horizontal acetabular sector angles for axial plane coverage detection, femoral anteversion, acetabular anteversion, and McKibbin instability index were also measured.

Results

Posterior coverage was lower at osteoarthritic hips than the control group’s hips (96.0 ± 16.7, 104.2 ± 10.6) (p < 0.05).

Conclusion

The results may indicate that in addition to other mechanical factors, axial plane coverage, especially the posterior coverage deficiency, may play a role in the pathogenesis of hip osteoarthritis.     

In situ screw fixation of slipped capital femoral epiphysis with a novel approach: a double-cohort controlled study

Purpose

In situ fixation for mild to moderate slipped capital femoral epiphysis (SCFE) remains an acceptable treatment methodology in most centers. Satisfactory fixation results have been reported with the procedure using either the fracture table or radiolucent table, both of which allow the hip to be imaged during the procedure. The position of the pin within the center of the femoral head is important to secure adequate fixation of the capital femoral epiphysis and prevent further slippage with minimal risk for articular penetration and avascular necrosis (AVN) or chondrolysis.

Methods

We describe a pre-operative planning technique to determine the pin-entry point for percutaneous pinning of SCFE on a radiolucent operating table. A retrospective review of patients who underwent in situ screw fixation with the usage of a cannulated screw on a radiolucent table or fracture table over a 6-year period was conducted.

Results

The pin-entry point with this technique was reliable in 92% of procedures and comparable in both accuracy and complications to in situ screw fixation on a fracture table. In situ screw fixation on a regular radiolucent table was straightforward and required significantly less surgical time than on the fracture table (P = 0.01). It was also more efficient during a bilateral procedure, as it required only a single preparation and draping of the patient.

Conclusion

This pre-operative planning technique for deciding the starting point on the proximal femur is helpful in executing an accurate in situ screw fixation of hips with SCFE.     

Is the Acetabulum Retroverted in SCFE? A Study of Acetabular Morphology in Indian Children with SCFE

BackgroundAcetabular morphology has always been an area of interest in patients with slipped capital femoral epiphysis (SCFE). Acetabular retroversion in SCFE is proposed as a pre-disposing factor and also can predispose the hip to pincer impingement. But there is controversial data in literature regarding the acetabular morphology. All available data are from the West and we present the first study on acetabular morphology in Indian children with SCFE.MethodsCT scans of 29 patients with SCFE were collected from our database and anteversion was measured as described by Dandachli et al. Lateral central edge angle (LCEA) was measured in the standard AP radiographs of the pelvis. There were 20 boys and 9 girls with a mean age of 13.5. Seven patients had right side SCFE, eighteen had left side SCFE, and four had bilateral involvement. Measurements were done in 33 affected hips and compared with 25 normal hips.ResultsThe mean AVsup and AVcen of affected hips were 6.59° and 13.51°, respectively, and that in normal hips were 8.36° and 14.04° (p > 0.05). The mean LCEA was 23.05° on the affected hips and 25.45° on the normal hips (p > 0.05). The AVsup showed retroversion in 24.24% (8/33) of the affected hips and 20% (5/25) of the normal hips. Though the mean version was less in SCFE hips, it was not statistically significant.ConclusionOur study documents that 25% of hips with SCFE had acetabular retroversion. However, this was not significantly high compared to the contralateral hips.     

Magnetic resonance arthrography for femoroacetabular impingement surgery: is it reliable?

Background

Magnetic resonance arthrography (MRA) is commonly used to demonstrate injury to the labrum and hyaline cartilage in patients with femoroacetabular impingement (FAI). The purpose of this study was to assess the diagnostic correlation between MRA and findings at arthroscopic and open surgery.

Materials and methods

MRA reports of 41 hips with symptomatic FAI were reviewed and compared with subsequent intraoperative findings (n = 21 surgical dislocations and n = 20 therapeutic hip arthroscopies). Each case was assessed for the presence of a cam deformity, a cartilage lesion of the femoral head, an os acetabuli, an injury to the labrum and injury to the acetabular cartilage. Results were collected prospectively in a cross-table and analysed retrospectively for sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

Results

The sensitivity, specificity, PPV and NPV in the presence of reported cam-type deformity or an os acetabuli were 100 %. In the presence of cartilage lesions of the femoral head, the values were 46, 81, 55 and 73 %, respectively. For labral tears, the values were 91, 86, 97 and 67 %. In the presence of acetabular cartilage injuries, the values were 69, 88, 78 and 81 %, respectively.

Conclusions

MRA appears to be an efficacious imaging modality in the evaluation of labral tears, cam-type impingement lesions and os acetabuli of the hip. MRA is less efficacious in the diagnosis of cartilage abnormalities in the hip, both femoral and acetabular. Researchers should focus on further improvements in imaging techniques in order to give reliable preoperative information to the surgeon.     

Symptomatic Femoroacetabular Impingement: Does the Offset Decrease Correlate With Cartilage Damage? A Pilot Study

Background

Current measures of the reduced head-neck offset such as residual deformity of slipped capital femoral epiphysis (SCFE) including the alpha angle, which measures the femoral head-neck sphericity but does not account for acetabular abnormalities, do not represent the true magnitude of the deformity and the mechanical consequences. The beta angle (angle between the femoral head-neck junction and acetabular rim) accounts for the morphology of both the acetabulum and femur and, thus, may be the more appropriate parameter for assessing SCFE deformity.

Questions/purposes

We determined (1) whether the beta angle could be reliably measured on MRI; and (2) whether the beta angle correlates with the cartilage status.

Methods

We recruited 10 adult patients (mean age, 28 years) with symptomatic cam femoroacetabular impingement and 15 asymptomatic volunteers (mean age, 24 years) to have three-dimensional MRI including delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) for cartilage status assessment. Corresponding alpha angles, beta angles, and acetabular dGEMRIC indices were obtained in seven radial reformats to assess the hip in seven regions (anterior to superior and posterior).

Results

We noted high reproducibility for both alpha and beta angle measurements. The dGEMRIC indices correlated with beta angles in the superoinferior and superior regions but not the alpha angles.

Conclusions

Beta angle measurement in radial MR images is reproducible and appears to correspond to cartilage damage in the superior regions of the hip. The beta angle may be a useful parameter to assess hip deformity in the followup of SCFE although further confirmation is warranted.     

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.