Chronic physeal fractures in myelodysplasia: magnetic resonance analysis, histologic description, treatment, and outcome

Diffusion tensor imaging of the physis: the ABC's

The physis, or growth plate, is the primary structure responsible for longitudinal growth of the long bones. Diffusion tensor imaging (DTI) is a technique that depicts the anisotropic motion of water molecules, or diffusion. When diffusion is limited by cellular membranes, information on tissue microstructure can be acquired. Tractography, the visual display of the direction and magnitude of water diffusion, provides qualitative visualization of complex cellular architecture as well as quantitative diffusion metrics that appear to indirectly reflect physeal activity. In the growing bones, DTI depicts the columns of cartilage and new bone in the physeal-metaphyseal complex. In this "How I do It", we will highlight the value of DTI as a clinical tool by presenting DTI tractography of the physeal-metaphyseal complex of children and adolescents during normal growth, illustrating variation in qualitative and quantitative tractography metrics with age and skeletal location. In addition, we will present tractography from patients with physeal dysfunction caused by growth hormone deficiency and physeal injury due to trauma, chemotherapy, and radiation therapy. Furthermore, we will delineate our process, or "DTI pipeline," from image acquisition to data interpretation.

Incidence, prevalence, and characteristics of fractures in children, adolescents, and adults with spina bifida

OBJECTIVE

To determine the age-specific incidence, prevalence, and characteristics of fractures in persons with spina bifida.

DESIGN

Year-long historical cross-sectional study.

SUBJECTS

Two hundred twenty-one consecutive patients aged 2-58 years evaluated in 2003 at a regional referral center. Twenty percent (n=44) were children age 2-10 years; 30% (n=68) were adolescents age 11-18 years; and 50% (n=109) were adults age 19-58 years. Fifty-five percent (n=121) were female; 64% (n=141) had shunted hydrocephalus. Fifty-eight percent (n=129) were community ambulators. Defect levels included 14% (n=31) thoracic; 37% (n=81) mid-lumbar; 35% (n=79) low-lumbar; and 14% (n = 30) sacral.

METHODS

Chart review of 221 consecutive children, adolescents, and adults enrolled in a spina bifida program in Syracuse, New York, was used to determine incidence and prevalence rates. Chi-square was used for subgroup analyses, and linear regression was used to examine independent association of motor level, functional independence (Functional Independence Measures score), body mass index (BMI), shunted hydrocephalus, epilepsy, and/or other congenital anomalies with fractures, controlling for insurance status, race/ethnicity, age, and sex.

RESULTS

Annual incidence of fractures among children, adolescents, and adults was 23/1000; 29/1000; and 18/1000, respectively. Overall prevalence was 200/1000. One in 4 patients with fractures reported multiple fractures. Median age at first fracture was 11 years. Most fractures involved the femur or tibia. Comparisons between adult- and childhood-onset fractures were not significant for difference in sex, BMI, defect level, functional independence, shunted hydrocephalus, epilepsy, or other congenital anomalies. In regression models only defect level RR = 1.646 (P = 0.019; 95% CI 1.085-2.498) and age RR = 1.033 (P= 0.036; 95% CI 1.002-1.065) were independently associated with fractures.

CONCLUSIONS

Fractures in persons with spina bifida are most common during early adolescence. Environmental modifications may be more effective than pharmacological treatment in reducing the prevalence of fractures in this population.

Deferoxamine-induced bone dysplasia in the distal femur and patella of pediatric patients and young adults: MR imaging appearance

OBJECTIVE

We investigated the MR imaging appearance of deferoxamine-induced bone dysplasia in the distal femur and patella in patients with thalassemia major.

MATERIALS AND METHODS

Thirty-five patients with homozygous ss-thalassemia major who were undergoing regular transfusions and chelation therapy underwent coronal T1-weighted MR imaging of the femur, including the femoral head and the distal femoral epiphysis. Additional coronal fat-saturated dual-echo and sagittal T1-weighted images of the distal femur and patella were obtained in 11 patients who were suspected of having distal femoral lesions on the basis of the coronal T1-weighted images of the entire femur.

RESULTS

No dysplastic change was detected in the proximal femur on coronal T1-weighted images. In 22 distal femurs of 11 patients, the following abnormalities were detected on MR imaging: blurred physeal-metaphyseal junction (n = 22), distal metaphyseal areas of hyperintensity (n = 21), physeal widening (n = 18), metadiaphyseal lesions (n = 11), epiphyseal lesions (n = 10), and patellar lesions (n = 2). Physeal widening and distal metaphyseal hyperintense areas were all more pronounced peripherally. Of the 21 distal metaphyseal hyperintensities, lateral abnormalities were larger than medial abnormalities in 16. Of the 18 distal femurs in which physeal widening was detected, the lateral widening was more marked than the medial widening in 12. Patients with MR imaging evidence of bone dysplasia have a significantly (p = 0.003) greater height reduction than patients without such evidence of bone dysplasia.

CONCLUSION

Deferoxamine-induced bone dysplasia in the distal femur and patella is represented by a spectrum of morphologic changes in the epiphysis, physis, metaphysis, and metadiaphysis on MR imaging.