Vitamin D in bone disease

Guided growth for pathological physes: radiographic improvement during realignment

BACKGROUND

Children with rickets are prone to having deformities of the lower extremities that are bilateral and often symmetrical. Although initially attributed to pathological or "sick" physes, the deformities are eventually seen in the metaphyses and diaphyses of the long bones; if left untreated, they may result in bone pain and stress fractures. The orthopaedists' role in managing these children is to correct and maintain alignment. Alternatively, we have exploited the use of hemiepiphysiodesis or guided growth, using staples or, more recently, the 8-plate (Orthofix, Verona, Italy). While gradually normalizing the mechanical axis, we have noted improvement in the appearance and width of all of the ipsilateral physes, not only at the knee but at the hip and ankle as well. This report summarizes our observations of the effects on the pathological physes in a group of patients with rickets who were preferentially treated with guided growth, often starting at a young age.

METHOD

This retrospective review approved by an institutional review board included 14 children with rickets, including 10 treated with staples and 4 with 8-plates, who collectively underwent a total of 68 hemiepiphysiodeses (guided growth) and 35 osteotomies. Each was under appropriate medical management during the entire course of treatment, before and after surgery. We measured the mechanical axis deviation and anatomic angles of the femur and proximal tibia, noting the width and appearance of their physes at the hips, knees, and ankles preoperatively and upon correction of the axis.

RESULTS

Of the 10 stapled patients, we noted 24 (45%) of 53 migrations and 41% rebound deformity. Four patients with 15 deformities that corrected with 8-plates experienced no hardware migration; for them, it is too early to comment on rebound deformity. While gradually correcting the mechanical axis, we have noted improvement in the appearance and width, not only of the pan-genu physes but also of remote physes at the hip and ankle. We suspect that the improved quality of the physes reflects not only the normalization of the mechanical axis but also the corresponding resolution of the waddling (varus) or circumduction (valgus) gait pattern.

CONCLUSION

We recommend early intervention, via guided growth, to restore and preserve a neutral axis so that the child can enjoy a normal lifestyle while maximizing the growth potential of his or her physes, not only of the knees but the hips and ankles as well. We believe that by correcting and maintaining alignment, secondary bony deformities may be ameliorated and osteotomies for angular correction deferred if not avoided altogether.

LEVEL OF EVIDENCE

IV (retrospective clinical series).

Hypophosphatemic rickets: the role of hemiepiphysiodesis

Despite early medical intervention, children with hypophosphatemic rickets often have progressive deformities in the lower extremities. With the forces imparted by gravity and weight bearing, varus or valgus deformities that might otherwise have been physiological are likely to progress, causing gait disturbance and pain. Proper medical management is important and may theoretically slow or prevent the progression of varus or valgus, but is ineffective at correcting deformity once established. We have reviewed the literature and gathered a series of 10 patients, most of whom underwent hemiepiphysiodesis. We are presenting the rationale for, and the results of, that surgery, in an effort to define the role of this minimally invasive procedure.

Pediatric Kidney Transplantation: Growth, Development, and Nursing Implications

The complex issues related to the growth and development of pediatric kidney transplant recipients are explored in this paper. We divide the pediatric population into 3 age groups—toddlers and preschoolers, school age children, and adolescents—and review the literature describing growth and development in kidney transplant recipients and the normal population briefly for each age group. Planning and delivery of nursing care that is based on the implications of growth and development are discussed, and have relevance for all allied healthcare professionals caring for pediatric kidney transplant recipients and their parents. Allied healthcare professionals in adult settings who provide care to recipients who received a transplant before the age of 18 may also benefit from reviewing this article.

Pediatric kidney transplantation: growth, development, and nursing implications

The complex issues related to the growth and development of pediatric kidney transplant recipients are explored in this paper. We divide the pediatric population into 3 age groups--toddlers and preschoolers, school age children, and adolescents--and review the literature describing growth and development in kidney transplant recipients and the normal population briefly for each age group. Planning and delivery of nursing care that is based on the implications of growth and development are discussed, and have relevance for all allied healthcare professionals caring for pediatric kidney transplant recipients and their parents. Allied healthcare professionals in adult settings who provide care to recipients who received a transplant before the age of 18 may also benefit from reviewing this article.

Imaging of metabolic bone disease and marrow disorders in children

There are a wide variety of metabolic and infiltrative diseases that involve the bones. Conventional radiography is the primary imaging examination for the initial evaluation of most of these disorders. MR imaging, however, provides detailed information about the bone marrow and is gaining an increasingly important role in the management of disorders of bone marrow infiltration.

Anesthesia and ventilation for the uremic child

This article reviews the management of the uremic child from the perspective of an anesthesiologist and cardiopulmonary clinician. The acute stresses of anesthesia, surgery, and mechanical ventilation mandate a systematic, functional approach to addressing rapidly progressing complications that may occur in these patients. Chronic renal failure may be the result of many different renal diseases, but most share common implications during anesthesia. Furthermore, anesthesia can be associated with acutely decreased function of both normal and diseased kidneys.

Parenteral calcitriol for treatment of severe renal osteodystrophy in children with chronic renal insufficiency

Renal osteodystrophy is a common and incapacitating complication of chronic renal failure in children. Standard therapy with oral calcium supplements, phosphate binders, and vitamin D preparations is often inadequate to control progressive bone disease. We report the use of parenteral calcitriol therapy in two children, aged 2 and 15 years, respectively, with chronic renal failure. This treatment effectively suppressed secondary hyperparathyroidism in both patients, causing a nearly 50% reduction in circulating parathyroid hormone level and a parallel decline in serum alkaline phosphatase activity. In the younger patient, therapy was associated with healing of subperiosteal bone resorption and accelerated growth velocity. These findings indicate that parenteral administration of calcitriol may be an effective treatment option in some patients with refractory renal osteodystrophy and secondary hyperparathyroidism.

Mandibular growth and histologic changes in condylar cartilage of rats intoxicated with vitamin D3 or 1,25(OH)2D3 and pair-fed (undernourished) rats

The mandibular condyles of 1,25(OH)2D3 or Vitamin D3 intoxicated rats were studied and compared with those of normal as well as pair-fed controls. Experimental animals were injected with either Vitamin D3 (2 mg/kg/day) or 1,25(OH)2D3 (400 ng/kg/day) for 19 days. Controls were given the solvent only, while pair-fed animals were restricted in their food intake for the same period of time, so that they exhibited a weight-curve similar to that of the experimental rats. The length of the mandibular ramus was measured in lateral radiographs of all mandibles. Demineralized coronal sections were obtained from all mandibular condyles and were stained with Mallory's connective tissue stain. The width of each zone within the condylar cartilage was measured. Experimental animals showed significant reduction in width of all layers within the condylar cartilage, with total lack of distinction between the maturation and hypertrophic zones. They also exhibited a significant retardation in growth of the mandible. Pair-fed animals had a normal width of the chondroprogenitor layer but significantly smaller maturation + hypertrophic zones (vs. controls). They also exhibited a significant retardation in mandibular growth but not to the same degree as did the intoxicated animals. Reduction in growth attributed to 1,25(OH)2D3 or Vitamin D3 intoxication is partly caused by undernutrition, which is a by-product of this condition. A further kinetic study is indicated to elucidate the mechanism of growth retardation and the differential effect on the various cartilage layers.

A computerized histomorphometric study of the effects of intoxication with vitamin D3 or 1,25 (OH)2D3 on growth and dentin production of impeded and unimpeded rat incisors

The effects of Vitamin D3 and 1,25(OH)2D3 intoxication on growth and dentinogenesis were studied in impeded and unimpeded rat incisors. Animals were intoxicated either with Vitamin D3 (2 mg/kg/day) or 1,25(OH)2D3 (400 ng/kg/day) for 19 days. Undecalcified transverse sections were obtained from all lower incisors. The outlines of all dental tissues were traced and fed into a computer which depicted the changes in all variables measured (circumference and cross-sectional area of tooth, pulp and dentin, width of dentin, CEJ [cemento-enamel junction] diameter and maximal labio-lingual diameter). Eruption rates, which had been recorded previously every 48 h, were used to compute the physiological age of each tooth site, so that only areas of similar age be compared. Growth. External dimensions of all intoxicated teeth decreased as the experiment progressed in contrast with control incisors which continued to increase in size. This effect was more pronounced in unimpeded incisors and may be due to the inhibitory influence of 1,25(OH)2D3 on cellular proliferation at the apical progenitor end. Dentinogenesis. 1,25(OH)2D3 intoxication had no significant effect on the rate of eruption and dentin formation in both impeded and unimpeded incisors. The same was true for impeded incisors intoxicated with Vitamin D3 but, both eruption and dentin production rates were impaired in Vitamin D3 unimpeded incisors.