Radiologists' Diagnostic Performance in Differentiation of Rickets and Classic Metaphyseal Lesions on Radiographs: A Multicenter Study

BACKGROUND. Despite evidence supporting the specificity of classic metaphyseal lesions (CML) for the diagnosis of child abuse, some medicolegal practitioners claim that CML result from rickets rather than trauma. OBJECTIVE. The purpose of this study was to evaluate radiologists' diagnostic performance in differentiating rickets and CML on radiographs. METHODS. This retrospective seven-center study included children younger than 2 years who underwent knee radiography from January 2007 to December 2018 and who had either rickets (25-hydroxyvitamin D level < 20 ng/mL and abnormal knee radiographs) or knee CML and a diagnosis of child abuse from a child abuse pediatrician. Additional injuries were identified through medical record review. Radiographs were cropped and zoomed to present similar depictions of the knee. Eight radiologists independently interpreted radiographs for diagnoses of rickets or CML, rated confidence levels, and recorded associated radiographic signs. RESULTS. Seventy children (27 girls, 43 boys) had rickets; 77 children (37 girls, 40 boys) had CML. Children with CML were younger than those with rickets (mean, 3.7 vs 14.2 months, p < .001; 89.6% vs 5.7% younger than 6 months; 3.9% vs 65.7% older than 1 year). All children with CML had injuries in addition to the knee CML identified at physical examination or other imaging examinations. Radiologists had almost perfect agreement for moderate- or high-confidence interpretations of rickets (κ = 0.92) and CML (κ = 0.89). Across radiologists, estimated sensitivity, specificity, and accuracy for CML for moderate- or high-confidence interpretations were 95.1%, 97.0%, and 96.0%. Accuracy was not significantly different between pediatric and nonpediatric radiologists (p = .20) or between less experienced and more experienced radiologists (p = .57). Loss of metaphyseal zone of provisional calcification, cupping, fraying, and physeal widening were more common in rickets than CML, being detected in less than 4% of children with CML. Corner fracture, bucket-handle fracture, subphyseal lucency, deformed corner, metaphyseal irregularity, and subperiosteal new bone formation were more common in CML than rickets, being detected in less than 4% of children with rickets. CONCLUSION. Radiologists had high interobserver agreement and high diagnostic performance for differentiating rickets and CML. Recognition that CML mostly occur in children younger than 6 months and are unusual in children older than 1 year may assist interpretation. CLINICAL IMPACT. Rickets and CML have distinct radiographic signs, and radiologists can reliably differentiate these two entities.

Debunking Fringe Beliefs in Child Abuse Imaging: AJR Expert Panel Narrative Review

Child abuse is a global public health concern. Injuries from physical abuse may be clinically occult and not appreciable on physical examination. Imaging is therefore critical in identifying and documenting such injuries. The radiologic approach for a child who has potentially been abused has received considerable attention and recommendations according to decades of experience and rigorous scientific study. Nonetheless, fringe beliefs describing alternative explanations for child abuse-related injuries have emerged and received mainstream attention. Subsequently, imaging findings identified in abused children have been attributed to poorly supported underlying medical conditions, clouding the evidence basis for radiologic findings indicative of nonaccidental trauma. Fringe beliefs that attribute findings seen in child abuse to alternate pathologies such as genetic disorders, birth trauma, metabolic imbalances, vitamin D deficiency, and short-distance falls typically have limited evidence basis and lack professional society support. Careful review of the scientific evidence and professional society consensus statements is important in differentiating findings attributable to child abuse from fringe beliefs used to discount the possibility that a child's constellation of injuries is consistent with abuse. This review refutes fringe beliefs used to provide alternative explanations in cases of suspected child abuse and reinforces the key literature and scientific consensus regarding child abuse imaging.

Spiral Fracture in Young Infant Causing a Diagnostic Dilemma: Nutritional Rickets versus Child Abuse

Fractures are uncommon in young, nonambulatory infants. The differential diagnosis includes nonaccidental injury (NAI) and metabolic bone disease, including rickets. While rickets typically present after six months of age, multiple cases have been reported in younger infants. We report a case of an 11-week-old male infant who presented with a spiral fracture of the humerus and no radiologic evidence of rickets. A detailed psychosocial assessment failed to reveal any risk factors for NAI. The patient had elevated alkaline phosphatase and PTH with low 25 hydroxyvitamin D and 1,25 dihydroxyvitamin D levels. Additionally, the mother was noncompliant with prenatal vitamins, exclusively breastfeeding without vitamin D supplementation, and had markedly low vitamin D levels 15 weeks postpartum. The biochemical data and history were consistent with rickets. Given the diagnostic dilemma, the working diagnosis was rickets and the patient was started on ergocalciferol with subsequent normalization of his laboratory values and healing of the fracture. These findings are consistent with nutritional rickets largely due to maternal-fetal hypovitaminosis D. This case highlights that in young infants rickets should be considered even in the absence of positive radiologic findings. Additionally, it illustrates the importance of maintaining adequate vitamin D supplementation during pregnancy and early infancy.

Absence of rickets in infants with fatal abusive head trauma and classic metaphyseal lesions

PURPOSE

To determine if rickets is present in cases of infant homicide with classic metaphyseal lesions (CMLs) and other skeletal injuries.

MATERIALS AND METHODS

This study was exempt from the institutional human subjects board review because all infants were deceased. An archival review (1984-2012) was performed of the radiologic and histopathologic findings of 46 consecutive infant fatalities referred from the state medical examiner's office for the evaluation of possible child abuse. Thirty infants with distal femoral histologic material were identified. Additional inclusion criteria were as follows: (a) The medical examiner determined that the infant had sustained a head injury and that the manner of death was a homicide, (b) at least one CML was evident at skeletal survey, (c) CMLs were confirmed at autopsy, and (d) non-CML fractures were also present. Nine infants (mean age, 3.9 months; age range, 1-9 months) were identified. Two pediatric radiologists independently reviewed the skeletal surveys for rachitic changes at the wrists and knees. A bone and soft tissue pathologist reviewed the distal femoral histologic slices for rickets.

RESULTS

There were no radiographic or pathologic features of rickets in the cohort.

CONCLUSION

The findings provide no support for the view that the CML is due to rickets. Rather, they strengthen a robust literature that states that the CML is a traumatic injury commonly encountered in physically abused infants.