The Relationship Between Fractures and DXA Measures of BMD in the Distal Femur of Children and Adolescents With Cerebral Palsy or Muscular Dystrophy

Children with limited or no ability to ambulate frequently sustain fragility fractures. Joint contractures, scoliosis, hip dysplasia, and metallic implants often prevent reliable measures of bone mineral density (BMD) in the proximal femur and lumbar spine, where BMD is commonly measured. Further, the relevance of lumbar spine BMD to fracture risk in this population is questionable. In an effort to obtain bone density measures that are both technically feasible and clinically relevant, a technique was developed involving dual-energy X-ray absorptiometry (DXA) measures of the distal femur projected in the lateral plane. The purpose of this study is to test the hypothesis that these new measures of BMD correlate with fractures in children with limited or no ability to ambulate. The relationship between distal femur BMD Z-scores and fracture history was assessed in a cross-sectional study of 619 children aged 6 to 18 years with muscular dystrophy or moderate to severe cerebral palsy compiled from eight centers. There was a strong correlation between fracture history and BMD Z-scores in the distal femur; 35% to 42% of those with BMD Z-scores less than −5 had fractured compared with 13% to 15% of those with BMD Z-scores greater than −1. Risk ratios were 1.06 to 1.15 (95% confidence interval 1.04–1.22), meaning a 6% to 15% increased risk of fracture with each 1.0 decrease in BMD Z-score. In clinical practice, DXA measure of BMD in the distal femur is the technique of choice for the assessment of children with impaired mobility. © 2010 American Society for Bone and Mineral Researc

Revised Pediatric Reference Data for the Lateral Distal Femur Measured by Hologic Discovery/Delphi Dual-Energy X-Ray Absorptiometry

BackgroundLateral distal femur (LDF) scans by dual energy x-ray absorptiometry (DXA) are often feasible in children for whom other sites are not measurable. Pediatric reference data for LDF are not available for more recent DXA technology.AimsTo assess older pediatric LDF reference data, construct new reference curves for LDF bone mineral density (BMD), and demonstrate the comparability of LDF BMD to other measures of BMD and strength assessed by DXA and by peripheral quantitative computed tomography (pQCT).MethodsLDF, spine and whole body scans of 821 healthy children, 5 to 18 years of age, recruited at a single center were obtained using a Hologic Delphi/Discovery system. Tibia trabecular and total BMD (3% site), cortical geometry (38% site) (cortical thickness, section modulus, strain strength index) were assessed by pQCT. Sex and race-specific reference curves were generated using LMS-ChartMaker and Z-scores calculated and compared by correlation analysis.ResultsZ-scores for LDF BMD based on published findings demonstrated overestimation or underestimation of the prevalence of low BMD-for-age depending on the region of interest considered. Revised LDF reference curves were generated. The new LDF Z-scores were strongly and significantly associated with weight, BMI, spine and whole body BMD Z-scores, and all pQCT Z-scores.ConclusionThese findings demonstrate the comparability of LDF measurements to other clinical and research bone density assessment modes, and enable assessment of BMD in children with disabilities, who are particularly prone to low trauma fractures of long bones, and for whom traditional DXA measurement sites are not feasible

Determination of safe return to play for athletes recovering from infectious mononucleosis: a review of the literature.

OBJECTIVE: Infectious mononucleosis is an acute self-limited disorder diagnosed by clinical and hematologic measures. This paper reviews the literature regarding the decision-making process for return to play in individuals at risk for complications due to infectious mononucleosis. DATA SOURCES: Computerized literature search identified articles using the keywords infectious mononucleosis, athlete, injury, exercise, spleen rupture, and spleen radiography. Symptoms, physical examination, hematological markers, and radiographic evaluation were considered. CONCLUSIONS: No strong evidence-based information supports use of a single parameter to predict the safe return to sports participation. Current consensus supports that athletes be afebrile, well hydrated, and asymptomatic with no palpable liver or spleen. Clinical judgment incorporating these criteria 1 month after diagnosis has been suggested as a safe predictor for gradual return to competition. These conditions for return to play do not guarantee that the spleen has returned to normal size and compliance, or that the risk of spleen rupture has returned to baseline. For those athletes participating in contact sports who wish to return to sports in an earlier time frame, or those with an equivocal examination, radiographic modalities may be used to help determine liver and spleen size. Further studies are required to support this practice

Bone mineral density in mucopolysaccharidosis IVB

To date, the only published reports of bone mineral density (BMD) in MPS IV involve patients with MPS IVA; no reports exist describing BMD for MPS IVB. In this prospective study of BMD in three patients with MPS IVB, BMD was acquired by dual-energy X-ray absorptiometry (DXA) at whole body (WB), lumbar spine (LS), and lateral distal femur (LDF). Functional abilities, ambulatory status, medical history, and height z-score were evaluated. Three patients with MPS IVB (two females), aged 17.7, 31.4 and 31.7 years, were evaluated. Every patient was ambulatory and one sustained two fractures caused by trauma. Whole body and hip DXA scans were technically invalid in every patient due to the presence of prosthetic hip hardware. Lumbar spine was valid in only 1 patient due skeletal abnormalities, and was normal (Z-score of −0.8). The LDF was valid in every patient and was low at all three regions of interest: average LDF z-scores were −3.1 (range, −2.9 to −3.6), −2.3 (range, −2.0 to −2.5), and −2.1 (range, −2.0 to −2.3) for region 1–region 3, respectively. Patients with MPS IVB have low BMD of the lower extremities even with full-time ambulation. Routine body sites to measure by DXA were problematic; hip and WB were invalid due to artifact, and LS had limited utility. The LDF was the only body site consistently available on all patients. Patients did not experience low-energy fractures despite low BMD

Placement of tibial intraosseous infusion devices.

Post-mortem preautopsy multidetector computed tomography was used to assess the placement of tibial intraosseous infusion needles in 52 cases of battlefield trauma deaths for which medical intervention included the use of the technique. In 58 (95%) of 61 needles, the tip was positioned in medullary bone. All 3 (5%) unsuccessful placements were in the left leg, and the needle was not directed perpendicular to the medial tibial cortex as recommended. Considering the nature of military trauma and the environmental conditions under which care is rendered, military medical personnel appear to be highly successful in the placement of tibial intraosseous infusion needles