ESPE Abstracts

Introduction: Osteoporosis in children and young people can be primary due to Osteogenesis Imperfecta (OI) or secondary to chronic disease. We report 2 patients with Idiopathic Juvenile Osteoporosis (IJO), a rare primary osteoporotic disorder.

Case 1: A 12 year old boy presented with 12 months of lower back pain and stiffness, against a background of chronic pain in knees, wrist and ankles. There was no history of fractures or systemic disease. Examination revealed normal anthropometry [height 154.1 cm (+0.42SDS), weight 38.3kg (+0.09SDS)] and pre-pubertal status. He had mild tenderness over the thoracolumbar spine, knee and ankle joints but no limitation of movement. He had no skeletal/extra skeletal manifestations of OI. X-ray and MRI of the spine revealed multiple thoracic vertebral compression fractures [T6-T10]. DEXA scan revealed a low lumbar spine bone mineral density (BMD) Z-score of -3.2. Further investigations ruled out secondary causes of osteoporosis. Iliac crest bone biopsy showed high turnover osteopenia, increased osteoid surface with no definite mineralization defect and was predictive of responsiveness to bisphosphonate therapy. He was commenced on intravenous zoledronic acid.

Case 2: A 14 year old boy was referred with severe back pain of subacute onset. He had several childhood fractures (wrist, ribs and navicular bone) and limb pains for 6 years prior to presentation. Examination revealed normal height [158 cm, +0.3 SDS), excessive weight [100 kg, +2.9 SDS) and signs of early puberty. MRI spine showed loss of height of T7 to L1 vertebrae. DEXA scan showed a lumbar spine BMD Z-score of −2.8. Investigations for secondary osteoporosis were normal and genetic testing was negative for common mutations in COL1A1/COL1A2. Bone biopsy showed adynamic bone with reduction in thickness of the cortices, osteoblast and osteoclasts. He received intravenous pamidronate therapy with symptomatic relief. Repeat DEXA scans after 1 and 3 years showed improvement in BMD Z-scores to −1.1 and +0.4 respectively. He is maintained on oral risedronate therapy.

Conclusion: IJO is a diagnosis of exclusion based on clinical and histological findings. Non-specific symptoms can lead to delay in the diagnosis. It should always be considered in the differential diagnosis of pre- and peri -pubertal adolescents with chronic back/bone pain in the absence of other causes. Bone biopsy is an important part of the diagnostic workup, however histology can be variable. Early diagnosis and appropriate therapy with bisphosphonates can promote bone remodelling thereby alleviating chronic pain and morbidity.