Osteogenesis imperfecta and other heritable disorders of bone

Results of Rodding and Impact on Ambulation and Refracture in Osteogenesis Imperfecta: Study of 21 Children

INTRODUCTION

Delay in presentation and surgical intervention is quite usual in osteogenesis imperfecta (OI) because of various local and cultural beliefs. The purpose of this study is to review the results of 21 children who had intramedullary rodding and its effect on ambulation and refracture.

METHODS

We reviewed 21 children with a clinical diagnosis of OI. The mean age of children at presentation was 8.74 years (3-21 years). All children had recurrent fractures of long bones. Twenty eight femurs and 21 tibiae were stabilized with intramedullary rodding. Ambulatory status was assessed by the Hoffers and Bullock's (H and B) grading, and muscle power was recorded using the Medical Research Council, U. K., grade. Ten children had received intravenous bisphosphonates preoperatively. Postoperatively, the children were assessed for ambulatory status, pain, and ability for independent self-care.

RESULTS

The mean followup period was 34 months (24-48 months). Rush rods were used in 20 femurs, the Fassier-Duval (FD) rods in 6 femurs, and in two cases, with narrow intramedullary canals, Kirshner (K) wires were used. For the tibiae, 15 children received rush rods and in 6 cases, an FD rod was used. The mean time to fracture union was 8 weeks (6-12 weeks). Before surgery, 13 children were in H and B Grade 4 (wheel-chair independent or carried by parents usually in a developing country), four were able to ambulate with a walking aid (H and B Grade 3b), and four children were able to walk about in the house without aids (H & B Grade 2). After the rodding procedure, the ambulatoty status improved in 11 (50%) children. Seven children (33%) became household physiologic walkers (H & B Grade 3b), three achieved independent ambulation with orthosis (H & B Grade 1b), and one child with mild OI could walk unaided (H & B Grade 1a). No child had deterioration in ambulatory status. Only two children had refractures at the distal end of the rod due to continual growth of bones.

CONCLUSIONS

Intramedullary rodding treatment for recurrent fractures in children with OI improves their mobility potential. It also and prevents repeated cast application, disuse wasting, and osteopenia which can lead to deterioration in the quality of the long bones.

Alternative option for osteogenesis imperfecta and trigeminal neuralgia

Summary Osteogenesis imperfecta (OI) is a bone disorder that can lead to skull base deformities such as basilar invagination, which can cause compression of cranial nerves, including the trigeminal nerve. Trigeminal neuralgia in such cases remains a challenge, given distorted anatomy and deformities. We present an alternative option, consisting in cannulation of the foramen ovale and classical percutaneous treatment. Percutaneous balloon microcompression was performed in a 28 year-old woman with OI and severe trigeminal neuralgia using computed tomography (CT) and radiographic-guided cannulation of the Gasserian ganglion without neuronavigation or stereotactic devices. The patient developed hypoesthesia on the left V1, V2 and V3 segments with good pain control. This alternative technique with a CT-guided puncture, using angiosuite without the need of any Mayfield clamp, neuronavigation systems, frame or frameless stereotactic devices can be a useful, safe and efficient alternative for patients with trigeminal neuralgia with other bone deforming diseases that severely affect the skull base.

The clinical features of osteogenesis imperfecta in Vietnam

PURPOSE

Osteogenesis imperfecta (OI) has not been studied in a Vietnamese population before. The aim of this study was to systematically collect epidemiological information, investigate clinical features and create a clinical database of OI patients in Vietnam for future research and treatment strategy development.

METHOD

Participants underwent clinical and physical examinations; also medical records were reviewed. Genealogical information was collected and family members' phenotypical manifestations recorded. Cases were classified according to the Sillence classification.

RESULTS

In total, 146 OI patients from 120 families were studied: 46 with OI Type I, 46 with Type III and 54 with Type IV. Almost patients had skeletal deformations. One hundred and forty-two had a history of fractures, 117 blue sclera, 89 dentinogenesis imperfecta and 26 hearing loss. The total number of fractures was 1,932. Thirty-four patients had intra-uterine fractures and nine had perinatal fractures. Surgery was performed 163 times in 58 patients; 100 osteosyntheses and 63 osteotomies. Bisphosphonate treatment was used in 37 patients. The number of affected individuals and predominance of severe forms of OI indicate that the disease is under diagnosed in Vietnam, especially in cases without a family history or with mild form of OI. Deformities appeared in all patients with different severity and localisation, affecting mostly the lower limbs. OI medical and surgical treatment rates are low and in most cases surgery was performed due to fractures.

CONCLUSIONS

Compared to previous studies, our results indicate a lower OI prevalence and greater severity of symptoms in the Vietnamese population when compared with other areas. Further investigation, improved diagnosis and treatment are needed to increase the patients' quality of life.

Bisphosphonate treatment in the oim mouse model alters bone modeling during growth

Osteogenesis imperfecta (OI) is a heritable disease, which results from an abnormal amount or structure of Type I collagen. Bisphosphonates, a class of synthetic antiresorptive drugs, used in osteoporosis management, are also used to decrease fracture incidence and improve quality of life in children with OI. In this study, we used the oim mouse to test the hypotheses that pamidronate treatment during active growth (1) produces larger, stronger, stiffer long bone diaphyses without altering bone material properties, and (2) negatively impacts longitudinal bone growth. Our results indicate that femoral cross-sectional moment of inertia in the distal metaphysis tended to increase with pamidronate treatment and that the treated bones are thicker and structurally stiffer, but shorter than their control-dose counterparts.

Intravenous pamidronate therapy in osteogenesis imperfecta: response to treatment and factors influencing outcome

Pamidronate treatment has been shown to improve outcome in osteogenesis imperfecta (OI); however, factors influencing outcome are unclear. The present study was conducted to evaluate the response to pamidronate therapy with special emphasis on factors influencing outcome. Twenty children with OI treated with pamidronate were evaluated in a prospective, open clinical trial. Pamidronate (9 mg x kg(-1) x yr) was administered intravenously at the age of 4.5 +/- 4.2 years for 2.9 +/- 0.7 years (range, 2-3.8 years). Treatment led to increase in bone mineral density (BMD) Z score by 0.7 +/- 0.3 every year resulting in significant improvement in BMD Z score (from -4.6 +/- 1.1 to -2.5 +/- 1.1, P<0.001). BMD Z score was within the reference range (>-2) in 9 subjects (45%) at the last follow-up as against none at initiation of treatment (P<0.001). Fracture rate decreased significantly during treatment (3.3 +/- 1.4 to 0.8 +/- 0.9, P<0.001) with 8 subjects (40%) having no fracture during the treatment period. Significantly greater proportion (88.2%) of children were able to walk at last follow-up compared with those at initiation of treatment (45.4%). Increase in BMD Z score and final BMD Z score was not influenced by age at initiation of treatment, duration of treatment, or initial BMD Z score. Treatment before infancy (n=7) was associated with higher final subjective score (6.3 +/- 0.5 vs 4.9 +/- 1.5, P=0.03). Our study reiterates the efficacy of pamidronate in OI. The poorer response of our subjects may be related to compromised calcium and vitamin D status.

A comparison of oral and intravenous bisphosphonate therapy for children with osteogenesis imperfecta

Bone mineral density and fracture rates in children with osteogenesis imperfecta improve with intravenous bisphosphonates. The efficacy of oral bisphosphonates has not been established. This report is an analysis of an open-label, prospective, randomized clinical trial of oral compared to intravenous bisphosphonate medications in children with osteogenesis imperfecta. Children were stratified according to bone age, pubertal stage, and type of osteogenesis imperfecta and then randomized to receive intravenous pamidronate, 3 mg/kg over 3 days every 4 months, or oral alendronate 1 mg/kg, from a minimum of 10 mg to a maximum of 20 mg daily. The primary efficacy outcome was change in bone mineral density. Secondary outcomes included change in biomarkers of bone turnover, fracture incidence, and growth rate. Ten children were randomized (6 oral and 4 intravenous). Two other children were assigned to intravenous treatment due to chronic abdominal pain. In each group, three patients had type III/IV osteogenesis imperfecta, while three had type I. All 12 children completed 8 months of therapy; nine completed 12 months. Bone mineral density increased in both oral and intravenous groups equally and beyond that expected with normal growth. All children had a decrease in biochemical markers of bone turnover. Linear growth showed a moderate increase above that for age. There was a non-significant decrease in fracture incidence in both groups.

Intravenous pamidronate treatment of children under 36 months of age with osteogenesis imperfecta

INTRODUCTION

Bone mineral density (BMD) and fracture rates in children with osteogenesis imperfecta (OI) have been shown to improve with bisphosphonate therapy. There are limited data available on the efficacy of this therapy in children with OI under the age of 3 years. To examine this, we instituted a prospective clinical trial of intravenous bisphosphonate to study safety, feasibility, and efficacy of this therapy.

MATERIALS AND METHODS

Nine infants and young children with osteogenesis imperfecta (age range 1-35 months) were treated with intravenous pamidronate. Six had type II OI, two had type I, and one had type IV. Pamidronate was administered in cycles of 3 consecutive days. The total duration of therapy ranged from 11 to 29 months (mean 17 months).

RESULTS

During treatment, the mean annualized percent change in total body areal BMD was 25% (range 11-40%). Pamidronate therapy resulted in sustained and significant decreases in serum calcium and bone-specific alkaline phosphatase and in urine calcium/creatinine and NTX/creatinine. Fracture rate in the group decreased from 80 fractures in 111 months before treatment to 25 fractures in 152 months after treatment (P<0.01). Linear growth and weight gain were maintained. Other than fevers in several infants following the initial dose of intravenous bisphosphonate no adverse effects of therapy were noted.

CONCLUSIONS

Our data support that intravenous pamidronate therapy is safe, increases BMD, and reduces fracture rates in very young children with OI. Currently, it would seem to be the best available treatment for these children.

Tamoxifen inhibits phorbol ester stimulated osteoclastic bone resorption: An effect mediated by calmodulin

Tamoxifen inhibits bone resorption by disrupting calmodulin-dependent processes. Since tamoxifen inhibits protein kinase C in other cells, we compared the effects of tamoxifen and the phorbol ester, phorbol myristate acetate, on osteoclast activity. Phorbol esters stimulate bone resorption and calmodulin levels four-fold (k0.5 = 0.1–0.3 µM). In contrast, tamoxifen inhibited osteoclast activity ~60% with an IC50 of 1.5 µM, had no apparent effect on protein kinase C activity in whole-cell lysates, and reduced protein kinase Cα recovered by immunoprecipitation 75%. Phorbol esters stimulated resorption in a time-dependent manner that was closely correlated with a similar-fold increase in calmodulin. Protein kinase Cα, β, δ, ε, and ζ were all down-regulated in response to phorbol ester treatment. Tamoxifen and trifluoperazine inhibited PMA-dependent increases in bone resorption and calmodulin by 85 ± 10%. Down-regulation of protein kinase C isoforms by phorbol esters suggests that the observed increases in bone resorption and calmodulin levels are most likely due to a mechanism independent of protein kinase C and dependent on calmodulin. In conclusion, the data suggest that protein kinase C negatively regulates calmodulin expression and support the hypothesis that the effects of both phorbol esters and tamoxifen on osteoclast activity is mediated by calmodulin.Key words: osteoclast, calmodulin, tamoxifen, osteoporosis, protein kinase C.