The "Discoid Epiphysis"-An Uncommon Presentation of Legg-Calvé-Perthes Disease.

BACKGROUND: Among a cohort of 402 children with Legg-Calvé-Perthes disease (LCPD), 32 children presented with sclerosis and severe collapse of the entire femoral epiphysis that closely resembled a discus.This study was undertaken to identify the characteristics of children with this form of a "discoid epiphysis," compare them with typical LCPD and ascertain the radiologic outcome of their hips when the disease healed. METHODS: Sequential radiographs of the children were studied to monitor disease evolution. Femoral epiphyseal extrusion was measured on the initial anteroposterior radiograph. Thirty-one of the 32 children were treated with a proximal femoral varus osteotomy and weight-bearing was deferred till the disease reached stage IIIb. The pattern of fragmentation of the epiphysis was noted and the Sphericity Deviation Score (SDS) was computed once the disease healed. RESULTS: The mean age of children with a discoid epiphysis was 6.81±1.57 years at onset of symptoms while that of children with the typical presentation was 7.54±1.64 years (P<0.017). Perfusion magnetic resonance imaging scans of three children with a discoid epiphysis done in stage Ib of the disease showed that over 95% of the epiphysis was avascular. Femoral head extrusion was frequently present on the initial radiographs (mean Reimer's migration index 27.08±8.7; range: 6.4 to 42.55).In operated children with a discoid epiphysis, the disease evolved typically with fragmentation of the epiphysis followed by reconstitution. The height of the epiphysis was never restored; when the disease healed the mean epiphyseal height was 51.31±10.44% of the normal contralateral epiphysis as compared with 82.46±11.24% in children with typical LCPD (P<0.001).The SDS at healing of operated children with a discoid epiphysis was 14.95±10.86 while the SDS for operated children without a discoid epiphysis was 9.77±11.7 (P<0.019). However, the SDS of children with typical onset LCPD who had Catterall IV involvement and Herring C collapse was 15.25±15.19 (P=0.49 NS). CONCLUSION: The outcome of treatment of children with a discoid epiphysis is comparable to that of children with typical onset LCPD with Catterall IV (whole-head involvement) and Herring C collapse of the lateral pillar. About a third of these children who undergo early surgical containment may have spherical heads when the disease heals.

Radiologic Outcomes of Bilateral and Unilateral Perthes Disease: A Comparative Cohort Study.

INTRODUCTION: This study was undertaken to compare the radiologic outcomes of bilateral and unilateral Perthes disease and also to evaluate the outcome of synchronous and metachronous bilateral Perthes disease. METHODS: Of 353 children with Perthes disease followed up from presentation to healing during the last 10 years, 37 had bilateral involvement (11 synchronous and 26 metachronous onset). The radiologic outcomes of each hip of children with bilateral disease were compared with outcomes of 148 children with unilateral disease who were matched for age, sex, and treatment. Children with unilateral or bilateral diseases were treated with a proximal femoral varus derotation osteotomy if they fulfilled the criteria for surgery. The primary outcome measure was the shape of the femoral head at healing assessed by the Sphericity Deviation Score (SDS). RESULTS: The children with bilateral disease were younger than those with unilateral disease (6.2 vs. 7.03 y; P<0.001), and they had a longer duration of the disease. All other characteristics of bilateral and unilateral cases were similar. The SDS values of unilateral and bilateral disease were comparable, as were the SDS of synchronous and metachronous bilateral disease. The effect of early surgery on the evolution of the disease in bilateral cases was similar to that reported in unilateral disease. The age of onset of the disease alone influenced the SDS in bilateral cases. CONCLUSION: The age at onset of the bilateral disease is lower, the duration of the disease longer than that of unilateral disease, but the disease outcome is similar.

Does the Deformity Index Reliably Predict the Shape of the Femoral Head at Healing of Legg-Calvé-Perthes Disease?

BACKGROUND: Treatment of Legg-Calvé-Perthes disease (LCPD) aims to preserve the spherical shape of the femoral head. The deformity index (DI) <0.3, measured 2 years from disease onset, is a surrogate measure that predicts that the femoral head will be Stulberg class I or II at skeletal maturity. There is no study that compares the predictive value of DI against a quantitative measure of the shape of the femoral head when the disease heals. We undertook this study to assess the reproducibility of a new method of measurement of DI and see if DI could predict the shape of the femoral head when the disease healed. METHODS: DI was measured 2 years after disease onset and the Sphericity Deviation Score (SDS) was measured at healing of LCPD on radiographs of 43 children. Reproducibility of measurement was tested. Each healed femoral head was classified as spherical or aspherical based on subjective visual assessment. The DI values were compared with SDS values. RESULTS: The reproducibility of measurement of SDS was excellent and superior to that of DI. The mean duration of disease was 3.97±0.96 years. Only 17 of 32 hips with DI values <0.3 at 2 years had spherical femoral heads at healing (SDS <10). Three hips with SDS values <10 had DI values >0.3. The positive and negative predictive values of a DI <0.3 in predicting if the femoral head will be spherical (SDS <10) when the disease healed were 53% and 73%, respectively. CONCLUSION: Though DI can be reproducibly measured the predictive value of a DI <0.3, to accurately identify hips that are likely to heal with spherical femoral heads, is not sufficiently high to justify its use as an outcome measure.

Reliability of 3 Radiologic Classifications for the Severity of the Developmental Dysplasia of the Hip in Children Older Than 4 Years.

BACKGROUND: Tonnis, International Hip Dysplasia Institute (IHDI), and lateral metaphyseal height (LMH) are commonly used classifications for grading the severity of the developmental dysplasia of the hip. The reliability of these classifications is not widely studied in older children. The aim of the study was to evaluate the reliability of these 3 radiologic classifications in children older than 4 years and compared with children younger than 4 years and evaluate the cases with varied inter-rater reliability. METHODS: A purposeful sample of 40 children with untreated developmental dysplasia of the hip with ages between 6 months to 8 years was studied for the assessment of the severity grading according to all 3 classifications. Six pediatric orthopaedic surgeons classified all hips for all 3 categorical classifications as per the original description. Inter-rater and intrarater reliability was calculated according to the intraclass correlation coefficient. The cases with different ratings were assessed in detail to evaluate the reasons for the varied rating. RESULTS: The interobserver and intraobserver reliability of all 3 classifications were excellent [intraclass correlation coefficient (ICC): 0.935, 0.820, and 0.935 for IHDI, Tonnis, and LMH classification, respectively]. The excellent reliability was also observed in younger and older children. Interobserver reliability of only dysplastic hips (52 hips) was good for Tonnis (ICC: 0.741) and excellent for IHDI (ICC: 0.911) and LMH classification (ICC-0.9). The main reason for the varied rating was because of the varied perception of the superolateral margin of the acetabulum in few hips. CONCLUSION: The inter-rater and intrarater reliability of all 3 classifications (IHDI, Tonnis, and LMH) is excellent. All classifications can be used till the age of 8 years. The difficulty in selecting the superolateral margin of the acetabulum is a major cause of inter-rater variability. LEVEL OF STUDY: Level III.