The classic metaphyseal lesion and traumatic injury

Post-mortem skeletal survey (PMSS) versus post-mortem computed tomography (PMCT) for the detection of corner metaphyseal lesions (CML) in children

OBJECTIVES

Corner metaphyseal lesions (CMLs) are specific for child abuse but challenging to detect on radiographs. The accuracy of CT for CML detection is unknown. Our aim was to compare diagnostic accuracy for CML detection on post-mortem skeletal surveys (PMSS, plain radiography) versus post-mortem CT (PMCT).

METHODS

A 10-year retrospective review was performed at a children's hospital for patients having PMSS, PMCT and histopathological correlation (reference standard) for suspected CMLs. Twenty-four radiologists independently reported the presence or absence of CMLs in all cases in a blinded randomised cross-over design across two rounds. Logistic regression models were used to compare accuracy between modalities.

RESULTS

Twenty CMLs were reviewed for each of the 10 subjects (200 metaphyses in all). Among them, 20 CMLs were confirmed by bone histopathology. Sensitivity for these CMLs was significantly higher for PMSS (69.6%, 95% CI 61.7 to 76.7) than PMCT (60.5%, 95% CI 51.9 to 68.6). Using PMSS for detection of CMLs would yield one extra correct diagnosis for every 11.1 (95% CI 6.6 to 37.0) fractured bones. In contrast, specificity was higher on PMCT (92.7%, 95% CI 90.3 to 94.5) than PMSS (90.5%, 95% CI 87.6 to 92.8) with an absolute difference of 2.2% (95% CI 1.0 to 3.4, p < 0.001). More fractures were reported collectively by readers on PMSS (785) than on PMCT (640).

CONCLUSION

PMSS remains preferable to PMCT for CML evaluation. Any investigation of suspected abuse or unexplained deaths should include radiographs of the limbs to exclude CMLs.

CLINICAL RELEVANCE STATEMENT

In order to avoid missing evidence that could indicate child abuse as a contributory cause for death in children, radiographs of the limbs should be performed to exclude CMLs, even if a PMCT is being acquired.

KEY POINTS

• Corner metaphyseal lesions (CMLs) are indicative for abuse, but challenging to detect. Skeletal surveys (i.e. radiographs) are standard practice; however, accuracy of CT is unknown. • Sensitivity for CML detection on radiographs is significantly higher than CT. • Investigation of unexplained paediatric deaths should include radiographs to exclude CMLs even if CT is also being performed.

Iatrogenic Flexion-Related Classic Metaphyseal Lesion of the Distal Tibia: Three Cases

BACKGROUND

Classic metaphyseal lesions (CMLs) should raise concern for nonaccidental trauma. However, iatrogenic causes for CMLs have increasingly been described and warrant close consideration. Increasing the clinical understanding of CML mechanics and their relation to often routine medical procedures will enhance provider awareness and expand the differential diagnosis when these otherwise highly concerning injuries are identified.

CASE REPORTS

We describe three clinical cases where suspected iatrogenic dorsiflexion or plantar flexion resulted in an isolated distal tibia CML. Respectively, we present heel-stick testing and i.v. line placement as clinical correlates of these two mechanisms. Although prior reports have aimed to describe iatrogenic CML etiologies, they have not focused on dorsiflexion or plantar flexion as predominant mechanisms of injury. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians are critical to the surveillance and identification of nonaccidental trauma. Given that children oftentimes present to the emergency department with subtle yet concerning signs of maltreatment, an emergency physician must be aware of the potential causes of injury as well as the recommended response. Although avoiding missed cases of abuse and improving the detection of injuries is crucial for child health and well-being, failing to consider or recognize alternative explanations could also have serious implications for a child and their caregivers.

Classic metaphyseal lesion: A rare presentation in an extreme preterm neonate

Classic metaphyseal lesions (CML) or bucket handle fractures are usually associated with child abuse or non-accidental injury. The most common sites affected are the distal femur, proximal and distal tibia, and proximal humerus. Few case reports documented its association with difficult extraction at delivery in term large for gestational age (LGA) neonates. We present a case of CML in an extremely preterm neonate following abnormal presentation and difficult cesarean delivery. Management of CML is usually conservative, and fractures heal without any deformities. Thorough history taking is essential in the diagnosis of CML.

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.

Child Abuse Imaging and Findings in the Time of COVID-19

OBJECTIVE

To assess the impact of the COVID-19 pandemic on physical abuse in young children, we compared the following before and during the pandemic: (1) skeletal survey volume, (2) percent of skeletal surveys revealing clinically unsuspected (occult) fractures, and (3) clinical severity of presentation. We hypothesized that during the pandemic, children with minor abusive injuries would be less likely to present for care, but severely injured children would present at a comparable rate to prepandemic times. We expected that during the pandemic, the volume of skeletal surveys would decrease but the percentage revealing occult fractures would increase and that injury severity would increase.

METHODS

We conducted a retrospective study of children younger than 2 years undergoing skeletal surveys because of concern for physical abuse at a tertiary children's hospital. Subjects were identified by querying a radiology database during the March 15, 2019-October 15, 2019 (pre-COVID-19) period and the March 15, 2020-October 15, 2020 (COVID-19) period, followed by chart review to refine our population and abstract clinical and imaging data.

RESULTS

Pre-COVID-19, 160 skeletal surveys were performed meeting the inclusion criteria, compared with 125 during COVID-19, representing a 22% decrease. No change was observed in identification of occult fractures (6.9% pre-COVID vs 6.4% COVID, P = 0.87). Clinical severity of presentation did not change, and child protective services involvement/referral decreased during COVID.

CONCLUSIONS

Despite a >20% decrease in skeletal survey performance early in the pandemic, the percent of skeletal surveys revealing occult fractures did not increase. Our results suggest that decreases in medical evaluations for abuse did not stem from decreased presentation of less severely injured children.

Multiple Abusive Fractures in an Infant With a Concurrent Parathyroid Hormone-Related Peptide-Secreting Renal Tumor: Abusive Fractures Accompanying a Parathyroid Hormone-Related Peptide-Secreting Tumor

BACKGROUND

When evaluating an infant with unexplained fractures for child abuse, it is important to evaluate for possible causes of underlying bone fragility.

CASE

A 7-month-old infant was found to have a parathyroid hormone (PTH)-related peptide-secreting mesoblastic nephroma. In spite of having an elevated serum calcium, depressed serum phosphate, and high levels of PTH-related peptide, he had no demineralization or other hyper parathyroid-related bone changes. Instead, he had multiple classic metaphyseal lesions, fractures of differing ages including a proximal clavicle fracture, and current and past bruising. No fractures typical of bone insufficiency were present. These findings are highly indicative of abuse in addition to his hormone-secreting tumor.

CONCLUSIONS

In spite of this child's abuse findings, endogenous or tumor-related hyper PTH should be in the differential of underlying bone fragility. Children with disorders that could cause injury susceptibility can also be abused.

Whole-body MR imaging in suspected physical child abuse: comparison with skeletal survey and bone scintigraphy findings from the PEDIMA prospective multicentre study

OBJECTIVES

To assess the contribution of whole-body magnetic resonance imaging (WBMRI) and bone scintigraphy (BS) in addition to skeletal survey (SS) in detecting traumatic bone lesions and soft-tissue injuries in suspected child abuse.

METHODS

In this prospective, multicentre, diagnostic accuracy study, children less than 3 years of age with suspected physical abuse were recruited. Each child underwent SS, BS and WBMRI. A blinded first review was performed in consensus by five paediatric radiologists and three nuclear medicine physicians. A second review investigated discrepancies reported between the modalities using a consensus result of all modalities as the reference standard. We calculated the sensitivity, specificity and corresponding 95% confidence interval for each imaging modality (SS, WBMRI and BS) and for the combinations [SS + WBMRI] and [SS + BS].

RESULTS

One hundred seventy children were included of which sixty-four had at least one lesion. In total, 146 lesions were included. The sensitivity and specificity of each examination were, respectively, as follows: 88.4% [95% CI, 82.0-93.1] and 99.7% [95% CI, 99.5-99.8] for the SS, 69.9% [95% CI, 61.7-77.2] and 99.5% [95% CI, 99.2-99.7] for WBMRI and 54.8% [95% CI, 46.4-63.0] and 99.7% [95% CI, 99.5-99.9] for BS. Sensitivity and specificity were, respectively, 95.9% [95% CI, 91.3-98.5] and 99.2% [95% CI, 98.9-99.4] for the combination SS + WBMRI and 95.2% [95% CI, 90.4-98.1] and 99.4% [95% CI, 99.2-99.6] for the combination SS + BS, with no statistically significant difference between them.

CONCLUSION

SS was the most sensitive independent imaging modality; however, the additional combination of either WBMRI or BS examinations offered an increased accuracy.

KEY POINTS

• SS in suspected infant abuse was the most sensitive independent imaging modality in this study, especially for detecting metaphyseal and rib lesions, and remains essential for evaluation. • The combination of either SS + BS or SS + WBMRI provides greater accuracy in diagnosing occult and equivocal bone injuries in the difficult setting of child abuse. • WBMRI is a free-radiation technique that allows additional diagnosis of soft-tissue and visceral injuries.

Accuracy of ultrasound in the diagnosis of classic metaphyseal lesions using radiographs as the gold standard

BACKGROUND

Diagnosis of classic metaphyseal lesions (CMLs) in children suspected for child abuse can be challenging. Ultrasound (US) can potentially help diagnose CMLs. However, its accuracy is unknown.

OBJECTIVE

To evaluate the accuracy of US in the diagnosis of CMLs using skeletal survey reports as the gold standard.

MATERIALS AND METHODS

US of the metaphysis was performed in three patient groups age <1 year. Informed consent was obtained for patients scheduled for renal US (Group 1) and for patients scheduled for skeletal surveys for possible child abuse (Group 2). Targeted US was also performed in selected patients to evaluate for possible CML suspected on radiographs (Group 3). In Groups 1 and 2, US was performed of both distal femurs, and of either the right or left proximal and distal tibia. Two radiologists (Rad1 and Rad2) independently reviewed the US studies, blinded to history and other imaging. US sensitivity and specificity were calculated using the following gold standards: CML definitely seen on skeletal survey (positive), CML definitely not seen on skeletal survey or part of renal US group (negative). Cases where the skeletal survey was indeterminate for CML were excluded. Kappa statistics were used to evaluate interobserver variability.

RESULTS

Two hundred forty-one metaphyseal sites were evaluated by US in 63 children (mean age: 5 months; 33 males); 34 had skeletal surveys and 29 had renal US. Kappa for the presence of CML was 0.70 with 95.7% agreement. US sensitivity was 55.0% and 63.2% and the specificity was 97.7% and 96.7% for Rad1 and Rad2, respectively.

CONCLUSION

US has low sensitivity and high specificity in CML diagnosis. Thus, negative US does not exclude CML, but when the radiographs are equivocal, positive US can help substantiate the diagnosis.

Are classic metaphyseal lesions pathognomonic for child abuse? Two cases of motor vehicle collision-related extremity CML and a review of the literature

Long bone fractures at the infant growth plate, known as classic metaphyseal lesions (CMLs), raise a strong suspicion for abusive injury. CMLs persist as a hallmark for inflicted injury although a handful of documented cases of CMLs created by other, non-abusive mechanisms within various healthcare settings are scattered throughout the past few decades of medical literature. The forces required to sustain a CML are typically defined as a combination of tensile, compressive, or rotational energy applied to the metaphyseal regions of an infant's long bones. Recently, two separate child protection teams each encountered a case of CML discovered after reported motor vehicle collisions (MVC). This provoked a critical appraisal of the medical literature to inform clinical practice regarding MVCs as a potential mechanism for this fracture type and to remind clinicians that there is no single injury pathognomonic for abuse.

Prevalence of metaphyseal injury and its mimickers in otherwise healthy children under two years of age

BACKGROUND

Metaphyseal lesions in infants and toddlers are believed to have a high specificity for inflicted injury.

OBJECTIVES

To examine the prevalence of metaphyseal injury and its mimickers in otherwise healthy children younger than 2 years of age.

MATERIALS AND METHODS

During 2010-2015, all children 2 years old and younger seen at the Accident and Emergency (A&E) Department due to an injury who had radiographs taken were included. Information on mechanism and clinical findings were drawn from the medical notes. All radiographs were reviewed by two of five researchers together with an experienced paediatric radiologist, registering fracture site and type, and metaphyseal appearances.

RESULTS

Four hundred and eight children (212 boys) (mean age: 17.7 months, range: 3-24 months) were included, of whom 149 (77 boys) had a total of 162 fractures (incidence of 5.4 per 1,000 children). Only one metaphyseal lesion, without a history of trauma, was seen. Of the 860 metaphyses analysed, 140 (16.3%) were defined as either irregular (74/860, 8.6%) or as having a metaphyseal collar (66/860, 7.7%). Sixty-four of the 66 collars (97.0%) and 54/104 irregularities (60.8%) were located around the wrist and the ankle, while 25/74 irregularities (33.8%) were found around the knee joint.

CONCLUSION

Metaphyseal lesions with a history of trauma did not occur in otherwise healthy neonates and infants younger than 2 years of age, indicating that this type of fracture has a particular trauma mechanism. Metaphyseal irregularities/collars are frequently seen and should not be mistaken for a classic metaphyseal lesion.

Classic Metaphyseal Lesions among Victims of Abuse

OBJECTIVE

To use legal statements by perpetrators to gain new insights into the causative mechanism of classic metaphyseal lesion (CML). The CML, so called "corner fracture," is considered a highly specific marker for abuse in infants. However, the precise correlation between CMLs and abusive head trauma is still unknown.

STUDY DESIGN

In this retrospective observational study, we selected 67 cases with at least 1 CML from a 15-year cohort of legally prosecuted child abuse cases. Their clinical, radiologic, and forensic records were analyzed. In 27 cases, the perpetrator confessed to abusing the child and described the events. Potential associations with subdural hematoma and with confession were evaluated using 2 separate binary logistic regression models.

RESULTS

All 67 infants showed other signs of abuse. Median age was 3.4 months. Over 65% had multiple CMLs. Knees and ankles were predominantly involved (64%). Only CMLs of the shoulder were significantly associated with subdural hematoma (P = .03). Different-age fractures were more common in the nonsubdural hematoma group (P = .01). In the group with confessions, perpetrators admitted inflicting violent indirect skeletal forces (torsion, traction, compression, and forced movements). The most common circumstance was diapering (44%), reported by male perpetrators only (P = .03) followed by dressing/undressing (30%). The violence was habitual in 67% of cases.

CONCLUSIONS

This unique forensic case series shows that CMLs are caused by violent acts inflicted most during physical care of infants. The frequency of habitual violence responsible for CMLs deserves greater attention.

Biomechanics of the classic metaphyseal lesion: finite element analysis

BACKGROUND

The classic metaphyseal lesion (CML) is strongly associated with infant abuse, but the biomechanics responsible for this injury have not been rigorously studied. Radiologic and CT-pathological correlates show that the distal tibial CML always involves the cortex near the subperiosteal bone collar, with variable extension of the fracture into the medullary cavity. Therefore, it is reasonable to assume that the primary site of bone failure is cortical, rather than intramedullary.

OBJECTIVE

This study focuses on the strain patterns generated from finite element modeling to identify loading scenarios and regions of the cortex that are susceptible to bone failure.

MATERIALS AND METHODS

A geometric model was constructed from a normal 3-month-old infant's distal tibia and fibula. The model's boundary conditions were set to mimic forceful manipulation of the ankle with eight load modalities (tension, compression, internal rotation, external rotation, dorsiflexion, plantar flexion, valgus bending and varus bending).

RESULTS

For all modalities except internal and external rotation, simulations showed increased cortical strains near the subperiosteal bone collar. Tension generated the largest magnitude of cortical strain (24%) that was uniformly distributed near the subperiosteal bone collar. Compression generated the same distribution of strain but to a lesser magnitude overall (15%). Dorsiflexion and plantar flexion generated high (22%) and moderate (14%) localized cortical strains, respectively, near the subperiosteal bone collar. Lower cortical strains resulted from valgus bending, varus bending, internal rotation and external rotation (8-10%). The highest valgus and varus bending cortical strains occurred medially.

CONCLUSION

These simulations suggest that the likelihood of the initial cortical bone failure of the CML is higher along the margin of the subperiosteal bone collar when the ankle is under tension, compression, valgus bending, varus bending, dorsiflexion and plantar flexion, but not under internal and external rotation. Focal cortical strains along the medial margins of the subperiosteal bone collar with varus and valgus bending may explain the known tendency for focal distal tibial CMLs to occur medially. Further research is needed to determine the threshold of applied forces required to produce this strong indicator of infant abuse.

Are There Hallmarks of Child Abuse? I. Osseous Injuries

Fractures are commonly found in cases regarded as child abuse. The most commonly encountered fractures are to the ribs and the metaphyses. This paper examines the specificity of the classical metaphyseal lesion (CML) and rib fractures as hallmarks of child abuse. Recently, vitamin D deficiency (rickets) has been proposed as an alternative cause for the appearances typically described in CML. The literature in this area is examined. Rib fractures have also been highly associated with child abuse, particularly posterior rib fractures. As well as metabolic bone disease, resuscitation has been examined as a cause of rib fractures in young children. The current literature remains strongly supportive of rib fractures and metaphyseal fractures being indicators of child abuse.