Growth of infants with osteogenesis imperfecta treated with bisphosphonate

Background:  Osteogenesis imperfecta (OI) is a heritable bone disease characterized by bone brittleness and various degrees of growth disorder. Cyclic pamidronate therapy is reportedly useful to prevent bone fracture in OI and in infants with OI, but, it remains unclear how infants with OI grow during bisphosphonate therapy.
Methods:  Height and weight measurements of OI infants treated with cyclic pamidronate therapy were taken before and every 6 months during therapy until 18 months. Vertebral morphometry and the concavity index were analyzed using X-ray films taken simultaneously.
Results:  Among OI patients, those in the group for which the height z- score decreased tended to have more femur fractures than those of the group for which the height z- score increased. Morphometry of the lumbar spine showed that compression fractures occurred less during cyclic pamidronate therapy, by which the lumbar bone mineral density increased.
Conclusions:  Bisphosphonate preserved vertebral morphometry during 18 months after starting therapy in infants. Prevention of femur fracture during the infantile period might help prevent short stature; therapeutic strategies during infancy must better emphasize prevention of long bone fracture before the beginning of gait.     

Bone densitometry in pediatric patients treated with pamidronate

Background: Increasing numbers of children are being treated with the bisphosphonate pamidronate for low bone mineral density, particularly children with increased risk of fractures caused by bone disorders or low/non-weight bearing. Objective: To determine the effect of intravenous pamidronate on the bone mineral density of children with osteogenesis imperfecta and spastic quadriplegic cerebral palsy. Materials and methods: Charts of 38 children with osteogenesis imperfecta (n=20) and spastic quadriplegic cerebral palsy (n=18) treated with pamidronate were retrospectively reviewed. Patients were selected for treatment because of prior fracture and/or abnormally low bone mineral density. All received intravenous pamidronate at two-month to eight-month intervals and were periodically examined using dual energy X-ray absorptiometry. Results: All patients had abnormally low bone mineral density prior to treatment. Lumbar spine bone mineral density and z-scores showed serial improvement in 31 of 32 patients. Spine bone mineral density increased 78±38.1% in OI and 47.4±39.0% in children with cerebral palsy. The area of greatest lateral distal femur bone mineral density improvement was in the metaphysis adjacent to the growth plate, with a 96±87.8% improvement in the osteogenesis imperfecta group and 65.7±55.2% improvement in the cerebral palsy group. Increases in bone mineral density exceeded that expected for age-specific growth. This was demonstrated by improvement in both spine and femur z-scores for both groups. No children with spastic quadriplegic cerebral palsy experienced fractures after the first week of treatment, whereas patients with osteogenesis imperfecta continued to have fractures but at a decreased rate. Conclusions: Intravenous pamidronate given at 3- to 4-month intervals proved to be effective in increasing bone mineral density in patients with osteogenesis imperfecta and spastic quadriplegic cerebral palsy. The greatest gains in bone mineral density were observed in the children with osteogenesis imperfecta, but they did continue to fracture, albeit at a decreased rate. Children with cerebral palsy gained bone mineral density and did not continue to fracture.     

Oral alendronate in osteogenesis imperfecta

We report a case of Osteogenesis Imperfecta (OI) in an eight-year-old boy who was admitted with complaints of recurrent long bone fractures. With oral alendronate treatment significant increment occurred in the bone mineral density and the number of fractures decreased. The usage of oral bisphosphonates is inexpensive and easy to administer in selected cases of OI. This case report supports the usage of oral alendronate treatment as an alternative treatment in OI.     

Intravenous pamidronate treatment of infants with severe osteogenesis imperfecta.

OBJECTIVE: Children with the severe forms of osteogenesis imperfecta have in several studies been treated with intravenous pamidronate, but there are only few reports of the effect of early treatment. AIM: To evaluate the effect of treatment started in infancy. METHODS: In a prospective observational study, with a historic control group, intravenous disodium pamidronate (APD) was given as monthly infusions to 11 children with osteogenesis imperfecta aged 3-13 (median 3.6) months, who had severe osteogenesis imperfecta with congenital bowing of the femora and vertebral compression fractures. RESULTS: During treatment of children aged between 3 and 6 (median 4.5) years, dual-energy x ray absorptiometry measurements of the lumbar spine showed a gradual increase in bone density. Bone metabolism parameters in serum (alkaline phosphatase, osteocalcin, procollagen 1 carboxy-terminal peptide, collagen 1 teleopeptide) and in urine (deoxypyridinoline) indicated a decrease in bone turnover. An improvement of mobility was seen and at the latest recording, at the age of 3.3-6.5 (median 4.8) years, the children could all walk. Vertebral remodelling was seen, with increased vertebral height, and no child developed scoliosis, kyphosis or basilar impression. All children required femoral intramedullar rods for fractures, and five needed tibial rodding for extreme curvatures that prevented functional standing and walking. No adverse effects were seen on growth, fracture healing or blood chemistry. CONCLUSIONS: APD is an efficient symptomatic treatment for infants with severe osteogenesis imperfecta, but additional orthopaedic surgery is often needed. Early treatment may prevent scoliosis and basilar impression. Long-term follow-up is important.     

Efficacy of low dose schedule pamidronate infusion in children with osteogenesis imperfecta

BACKGROUND: Osteogenesis imperfecta (OI) is a rare condition in which bones are abnormally brittle with frequent fractures. A variety of therapeutic agents has been used with low efficacy. In this study, we present three patients treated for 4 years with i.v. pamidronate. PATIENTS AND METHODS: Three prepubertal patients, aged 9 (M), 9 (F) and 11 (F) years old, with OI, were treated with 30-60 mg i.v. pamidronate every 6 months over four years. Determinations were made of plasma 1,25-dihydroxycholecalciferol, 25-hydroxycholecalciferol, insulin-like growth factor-I (IGF-I) and its transport protein (IGFBP3), osteocalcin, total alkaline phosphatase and its osseous fraction, and parathormone (PTH) at baseline and after every pamidronate infusion, Densitometry and X-ray of the vertebral column were performed at the same intervals. RESULTS: Significant reductions of number of bone fractures and pain were observed in all patients, despite lack of any modification in biochemical parameters. Lumbar X-ray and densitometry showed a striking improvement by the end of the treatment period. CONCLUSION: Pamidronate seems to be useful in the treatment of patients with osteogenesis imperfecta.     

Oral bisphosphonate treatment for osteogenesis imperfecta--an Indian perspective

BACKGROUND: Various treatments for the management of osteogenesis imperfecta (OI) have been tried, of which bisphosphonates seem to have the maximum benefit in reducing fracture rate and improving bone density. This study investigated the value of oral alendronate for treating OI in Indian children. METHODS: Between 2002 and 2005, 11 patients with OI were referred for bisphosphonate therapy. The various types of OI were classified using the Sillence criteria. All patients underwent baseline biochemistry, radiographic studies and bone mineral density (BMD) measurements before commencing therapy. Patients were commenced on oral alendronate (0.5 mg/kg/day) and followed up for a period ranging from 1 month to 2 years. A retrospective analysis of pre- and post-treatment changes in fracture rate and bone density was undertaken using the paired sample t-test. RESULTS: One patient lost to follow-up was excluded from the study and three completed only 2 months of therapy. Pre-treatment fracture rate per year before treatment ranged from 0.5 to 6 with a mean (SD) of 2.95 (1.57) and median of 2.5. The post-treatment fracture rate was 1.1 (0.59)/year (p=0.02). Seven children underwent BMD analysis while on treatment and all had a rise in BMD, of which the change in lumbar spine BMD was statistically significant (p=0.001), and lumbar (p=0.005) and femoral neck t-score (p=0.04) showed a significant change. No significant change was seen in serum biochemistry except for disappearance ofhypercalciuria (p=0.04). No child had an adverse reaction to alendronate. CONCLUSION: After a median of 9.5 months of treatment, oral alendronate is associated with a lower fracture rate, improvement in BMD and a decrease in hypercalciuria.     

Effect of 1,25(OH)2-vitamin D on bone mass in children with acute lymphoblastic leukemia

BACKGROUND: Calcitriol deficit has been described in patients with acute lymphoblast leukemia (ALL). The aim of this randomized case-control trial is to investigate the effectiveness of calcitriol administration during the first year of treatment to protect bone mass. Sixteen children recently diagnosed with ALL, aged 1.7 to 11.5 years, average 5.5, completed the study. Anthropometrical measurements, food intake record, physical activity, and bone pain were registered. Dual energy x-ray absorptiometry was performed at the completion of remission induction chemotherapy (after 1 mo) to measure bone mineral density (BMD) at hip, lumbar spine and whole body, and total bone mineral content and 1 year after. Half of them were randomly assigned to receive calcitriol during 1 year. STATISTICAL: Kruskal-Wallis, Wilcoxon, Mann-Whitney, and Spearman. RESULTS: Both groups had similar anthropometric measurements and bone densitometric variables increments. Spine BMD significantly increased in calcitriol supplemented children with lower baseline BMD (r=-0.78 and P<0.05). CONCLUSIONS: One-year calcitriol administered to recently diagnosed ALL children did not show impact on bone mass. Greater increment in lumbar spine bone mass was observed in patients who received calcitriol and had lower baseline BMD.     

Alendronate treatment in children with osteogenesis imperfecta

BACKGROUND: Recent studies reported beneficial effect of cyclical intravenous administration of pamidronate in children and adolescents with osteogenesis imperfecta (OI). However, this treatment requires frequent hospital admissions and is relatively expensive. Alendronate is an oral bisphosphonate effectively used in adults with osteoporosis. Experience with alendronate treatment in children with OI is limited. AIMS: To report our experience with alendronate in children with OI. METHODS: 12 children with OI (7 with type I, 4 with type III and 1 with type IV; 7 boys, 5 girls) aged 1.8 to 15.4 years (7.9+/-; 4.4 yrs) were included in this retrospective study. The patients were treated with alendronate in a dose of 5-10 mg/day along with calcium (500 mg/day) and vitamin D (400-1000 IU/day) supplements for 19.8+/-11.3 months (range: 7-46 months). Serum calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), osteocalcin (OC), pyrilinks-D and urinary Ca/Cr ratio were studied 3 monthly and bone mineral density (BMD) by DXA on 6-12 monthly basis. RESULTS: Fracture rate of the patients significantly decreased after treatment (1.2+/-1.5 vs. 0.16+/-0.32 per year, P<0.05). Treatment improved bone density in each individual case. Z-scores of lumbar DXA (L2-L4) significantly increased during treatment (-4.60+/-1.30 vs - 2.47+/-1.52, P< 0.05). Urinary pyrilinks-D decreased with treatment (90.8+/-136.3 vs. 35.1+/-29.9, P< 0.05). Serum Ca, P, ALP, OC and urinary Ca/Cr did not change significantly during treatment. CONCLUSION: We conclude that alendronate is effective, safe and practical alternative to intravenous bisphosphonates in treatment of children with OI.     

Alendronate treatment for infants with osteogenesis imperfecta: demonstration of efficacy in a mouse model

Recent non-placebo-controlled studies of the bisphosphonate pamidronate have shown it to be effective in reducing fractures and improving bone density in infants and children with osteogenesis imperfecta (OI). To evaluate the effects of bisphosphonate treatment in a controlled study, the oim/oim mouse model of OI was studied. Nursing infant mouse pups (approximately 2 wk old) with moderate to severe OI (oim/oim mouse) and age- and background-matched control mice (+/+) were treated either with the third-generation bisphosphonate alendronate (ALN), or with saline. Fracture risk, bone quality, and growth were evaluated over a 12-wk treatment period. ALN at a dose of 0.03 mg/kg/d or saline was administered via s.c. injection to infant oim/oim and wild-type (+/+) mice from 2 to 14 wk of age (n = 20 per subgroup). The average number of fractures sustained by the ALN-treated oim/oim mice was reduced significantly compared with the untreated oim/oim mice (0.7 +/- 0.7 fractures/mouse versus 2.0 +/- 0.2 fractures/mouse). Bone density increased significantly in the femur and the spine with treatment (2.0 +/- 0.5 versus 1.2 +/- 0.5 in femur and 2.1 +/- 0.5 versus1.6 +/- 0.5 in spine). Histologic evaluation revealed the percentage of metaphyseal tibial bone increased significantly with treatment in both +/+ and oim/oim mice. Mechanical testing revealed an increase in structural stiffness for both treated +/+ and oim/oim mice compared with untreated animals. None of the material properties examined were significantly altered with treatment, nor was spinal curvature affected. Weight gain and long bone growth were comparable in the treated and untreated oim/oim mice. In wild-type mice, femur lengths were significantly shorter in the treated mice compared with untreated counterparts. This animal study demonstrates that treatment of OI in mice as early as 2 wk of age with ALN appears to be effective in reducing fractures and increasing bone properties. Based on the data from this study, ALN therapy in infants with OI should prove to be effective.     

Bone mineral density and bone acquisition in children and young adults with cystic fibrosis: a follow-up study

OBJECTIVE: To investigate bone mineral density and bone homeostasis in cystic fibrosis (CF) and to assess changes in a 2-year period. METHODS: Thirty-eight patients with clinically stable CF (11 children, 16 adolescents, 11 young adults) were enrolled. No patient was treated with corticosteroids before or during the study. Weight and height Z scores and bone mineral density (BMD) Z-score at the femoral neck and the lumbar spine were recorded at the beginning of the study and after 2 years. Osteocalcin and cross-link excretion, both measurements of bone turnover were also measured. Correlations between BMD, bone turnover parameters, disease severity, pubertal stage, and nutritional state were calculated. The maternal BMD was also determined and related to that of the child. RESULTS: Height and weight Z scores were normal in children and below normal in adolescents. Puberty was delayed in most patients. Bone age was lower than chronological age in adolescents. Lumbar spine and femoral neck BMD Z scores were below normal in each age group. Disease severity determined by Schwachman score correlated with lumbar BMD (r = 0.45, P < 0.02). BMD Z scores did not change during 2 year follow-up. Maternal and patient lumbar and femoral BMD correlated significantly (r = 0.51, P < 0.01, and r = 0.54, P < 0.01, respectively). CONCLUSIONS: Bone deficit is present in patients with CF who have never received steroid treatment. Delay of puberty, chronic inflammation, or genetic susceptibility might be responsible for this phenomenon which was found in patients who had never received steroids and who were in relatively good clinical state.     

Decreased bone density and treatment in patients with autosomal recessive cutis laxa

Aim: Due to the occasional association pathological fractures and osteoporosis we evaluated four patients with cutis laxa syndrome for skeletal anomalies.
Patient/Methods: We prospectively evaluated four patients, a male and a female child and a brother-sister sib pair, with dysmorphic features, growth delay, joint anomalies, psychomotor retardation and congenital cutis laxa. The clinical features and the family history were suggestive for autosomal recessive cutis laxa syndrome type II, partially overlapping with geroderma ostedysplastica. Skeletal survey, sequential bone density measurements, endocrine and metabolic investigations were performed including N- and O-linked glycosylation analysis. ATP6V0A2 and FBLN5 mutations were ruled out in all patients.
Results: All children were diagnosed with significantly decreased bone density, especially in the lumbar spine, including spontaneous vertebral and rib fractures in three children. Following 24 months of bisphosphonate treatment a total restitution of bone density was observed in three cases and no relapse was detected in the 2-year follow-up period. A spontaneous improvement was found in one female during puberty.
Conclusion: Bone disease might occur early in the course in autosomal recessive cutis laxa syndrome. We report on a significant clinical improvement and stabilization in our patients following bisphosphonate therapy. We suggest early, systemic evaluation and follow up of bone density in all children presenting with inherited cutis laxa.     

Quantitative ultrasonometry of the calcaneus in children with osteogenesis imperfecta

Aims: Osteogenesis imperfecta (OI) is characterised by low bone density and increased bone fragility. The aim was to evaluate calcaneal quantitative ultrasonometry (QUS) parameters in children with OI and to look for relationship with the number of prevalent fractures. Methods: Eighteen children (12 boys and six girls; mean age 9.8 ± 3.5 years) with OI (type I, n= 15; type IV, n= 3; mean fracture prevalence 3.7 per patient) had the velocity of sound (VOS) and broadband ultrasound attenuation (BUA) measured on both heels with a Cuba Clinical (McCue Ultrasonics, Winchester, UK) dry ultrasound portable device. Both BUA and VOS were expressed as either age‐dependent or height‐related values. The obtained values of VOS and BUA were correlated to number of prevalent fractures. Results: The patients were of short stature (Z‐score –1.73 ± 1.20 SD; P < 0.001). Both age‐related BUA and VOS were low in comparison to reference values (P < 0.0001), same as height‐adjusted BUA and VOS (P < 0.0001). We found no correlations between number of prevalent fractures and BUA or VOS (age‐related or height‐adjusted) (r= 0.02, r= 0.017, r=–0.13, r= 0.015, respectively). Conclusions: Children with OI have low QUS parameters with no relationship to number of prevalent fractures.     

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.     

Beneficial effect of long term intravenous bisphosphonate treatment of osteogenesis imperfecta.

AIM: To find an effective symptomatic treatment for osteogenesis imperfecta (OI). METHODS: In a prospective observational study disodium pamidronate (APD) was given as monthly intravenous infusions to 28 children and adolescents (aged 0.6-18 years) with severe OI or a milder form of the disease, but with spinal compression fractures. RESULTS: During treatment for 2-9 years, dual energy x ray absorptiometry measurements of the total body and of the lumbar spine showed a gradual increase in bone density. All bone metabolism variables in serum (alkaline phosphatase, osteocalcin, procollagen 1 C-terminal peptide, collagen 1 teleopeptide) and urine (deoxypyridinoline) indicated that there was a decrease in bone turnover. All patients experienced beneficial effects and the younger patients reported a major improvement in wellbeing, pain, and mobility without significant side effects. Vertebral remodelling was also seen. CONCLUSIONS: APD seems to be an efficient symptomatic treatment for children and adolescents with OI.     

Management of lower limb deformities in children with osteogenesis imperfecta

Osteogenesis imperfecta (OI) often leads to severe lower limb (LL) deformities due to recurrent fractures that significantly hamper ambulation. We describe our management experience of correction of LL deformities in four children with OI. Medical management consisted of peri and postoperative pamidronate therapy, calcium supplementation and rehabilitative care. Deformities were corrected with multiple osteotomies and intramedullary fixation by titanium elastic nails. At a mean follow-up of 30 months, all children have significantly reduced fracture incidence and have no evidence of recurrence of deformities with improved ambulatory status. We emphasize the importance of combined medical and surgical therapy for these patients.     

Osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a rare congenital disorder of collagen production that results in brittle bones and affects other body systems containing collagen. This article reviews the current body of knowledge about OI and the management of infants with the disorder. Relieving pain, reducing the incidence of new fractures, establishing adequate follow-up, and connecting parents with community resources are the goals of management during the neonatal period. A case study illustrates management and the discharge process.     

Neurosurgical implications of osteogenesis imperfecta in children. Report of 4 cases

Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by disruption of normal collagen formation resulting in varying degrees of skeletal vulnerability, ligamentous laxity, and scleral discoloration. Children with OI may suffer from complex neurosurgical problems affecting the brain and spine. The authors sought to determine the neurosurgical implications of OI in a cohort of patients treated at a quaternary care center for pediatrics. The authors reviewed the case histories of 10 children with OI treated by the neurosurgical service at the Hospital for Sick Children in Toronto between January 1988 and March 2007. The cases of 4 of these children are highlighted in the article. The most common neurosurgical conditions encountered in this cohort included macrocephaly in 5 patients, subdural hematoma in 3 patients, epidural hematoma in 2 patients, and hydrocephalus in 3 patients. Basilar invagination and spinal fractures were observed in 20% of the cohort. Although some patients could be treated nonoperatively, several required craniotomy for clot evacuation, decompression, and spinal fixation for fracture or basilar invagination, and cerebrospinal fluid shunt insertion. Neurosurgical conditions affecting patients with OI include macrocephaly, the development of an acute intracranial hematoma after often minimal trauma, the development of chronic subdural fluid collections that may require drainage, hydrocephalus (both communicating and noncommunicating), basilar invagination, and subaxial spinal fractures. Surgery may be complicated in some children because of the underlying bone fragility and bleeding diathesis commonly observed in patients with OI.     

Beneficial effect of long term intravenous bisphosphonate treatment of osteogenesis imperfecta

Aim: To find an effective symptomatic treatment for osteogenesis imperfecta (OI). Methods: In a prospective observational study disodium pamidronate (APD) was given as monthly intravenous infusions to 28 children and adolescents (aged 0.6–18 years) with severe OI or a milder form of the disease, but with spinal compression fractures. Results: During treatment for 2–9 years, dual energy x ray absorptiometry measurements of the total body and of the lumbar spine showed a gradual increase in bone density. All bone metabolism variables in serum (alkaline phosphatase, osteocalcin, procollagen 1 C-terminal peptide, collagen 1 teleopeptide) and urine (deoxypyridinoline) indicated that there was a decrease in bone turnover. All patients experienced beneficial effects and the younger patients reported a major improvement in wellbeing, pain, and mobility without significant side effects. Vertebral remodelling was also seen. Conclusions: APD seems to be an efficient symptomatic treatment for children and adolescents with OI.     

Low-dose intravenous pamidronate treatment in osteogenesis imperfecta

Different therapy models have been tried in order to decrease bone resorption in osteogenesis imperfecta. Bisphosphonates are a group of drugs that mainly suppress osteoclast-mediated bone resorption, thus reducing bone turnover. We assessed the effects of low-dose bisphosphonate treatment in children with osteogenesis imperfecta. Sixteen osteogenesis imperfecta patients (12 female, 4 male) with severe deformities were treated with cyclic (3-4 mg/kg/year) intravenous infusions of bisphosphonate (Aredia-Novartis) therapy for a period ranging from 0.6 to 4.7 years (mean 2.50 +/- 1.09 years). Bone mineral density increased from 0.304 +/- 0.146 g/cm2 to 0.362 +/- 0.142 g/cm2 in the first year and to 0.421 +/- 0.146 g/cm2 in the second year. A clinical response was shown with a reduction in fracture rate and improvement in mobilization scores. Fracture rates decreased from a median of 4/year (0-30/year) before treatment to 0/year (0-5/year) during treatment. Ambulation improved in 10 children and remained unchanged in three. Two of the children were fully functional before therapy and one was below two years of age. No adverse effects were seen with pamidronate infusions of 7-10 mg/kg/year (monthly) or with 4 cycles/year 3-4 mg/kg/year. Low-dose cyclical pamidronate infusions markedly increased bone density and decreased bone fracture rate and should be considered as a part of a multi-disciplinary treatment.     

Pamidronate treatment of less severe forms of osteogenesis imperfecta in children

BACKGROUND: Bisphosphonate therapy improves bone quality in children with severe osteogenesis imperfecta (OI). Children with milder phenotypes also have prepubertal fractures, bone pain and reduced bone mass, predisposing them to adult osteoporosis. OBJECTIVE: To evaluate treatment effects of pamidronate in children with mild phenotypes of OI. METHODS: Open label, 2-year observational study of 18 patients, using pamidronate, with clinical, biochemical and radiological monitoring. RESULTS: Over 2 years, bone pain decreased from 16 to 1 patient and disturbed sleep from 12 children to 0. Independent mobility improved from 10 to 17 children. Fracture incidence decreased from 1.6 to 0.5 fractures/child/year. Surgical interventions decreased from a mean 1.3 procedures/patient to 0 in the second year of treatment. Growth velocity remained stable at a mean 4.8 cm/year. Mean lumbar vertebral bone mineral density improved by 40.8%, from 0.375 to 0.528 g/cm2 (p <0.0001), z-score from -3.77 to -2.44 (p <0.0001). Mean vertebral height improved by 17.3%, from 15.6 to 18.38 mm (p = 0.07); plasma alkaline phosphatase decreased from 222 to 169 U/l (p = 0.0009) and urinary deoxypyridinoline crosslinks decreased from 26.7 to 21.8 nmol/mmol creatinine (p = 0.21). Two children with vitamin D insufficiency were concurrently treated. A significant association (r = -0.6, p = 0.008) was shown between age at start of treatment and percentage change in BMD after 2 years. CONCLUSIONS: Pamidronate treatment improves bone quality in children with mild types of OI. It ameliorates clinical symptoms, improves mobility, reduces fracture frequency and thus improves quality of life and in future is likely to reduce the severity and consequences of adult osteoporosis by improved peak bone mass in these children.