Bone Abstracts

Objectives: To examine the bone mineral density (BMD) response to i.v. pamidronate (Group 1) vs i.v. zoledronic acid (Group 2) in non-ambulatory children and young adults with severe cerebral palsy or other neuromuscular disorders.

Methods: A total of 50 non-ambulatory children and young adults, (mean age 11.3 years, range 2.1–32) with low BMD and/or history of fractures were retrospectively studied. Thirty-nine patients (30 spastic quadriplegic cereal palsy, 6 spinal muscular atrophy, 3 myelomeningocele) were treated with IV pamidronate (from 1999–2007). Eleven patients (seven spastic CP, two spinal muscular dystrophy, and two myelomeningocele) were treated with zoledronic acid (from 2006–2011). I.v. pamidronate, 1 mg/kg per day was administered three consecutive days, repeated at 3-month intervals for the first year. I.v. zoledronic acid, at 0.025 mg/kg per dose, was given at 3-month interval for the first year. Frequency of both treatments was decreased in subsequent years to every 4, 6 or 12 months depending on BMD response. Lumbar BMD (Hologic DEXA), Z-score (adjusted for weight and pubertal status) at baseline and 1, 2 and 3 years were analyzed.

Results: Mean lumbar BMD Z-score increased significantly from baseline to 1, 2, and 3 years in both groups (P< 0.01): from −3.89 at baseline to −2.68 at 1 year, −1.97 at 2 years, and −1.73 at 3 years in Group 1; from −3.89 at baseline to −2.43 at 1 year, −1.52 at 2 years, and −1.35 at 3 years in Group 2. There was no significant difference in BMD Z-score response between groups; treatment was well tolerated with no serious adverse reactions.

Conclusion: Both pamidronate and zoledronic acid treatment are effective in improving BMD and BMD Z-score in children and young adults with neuromuscular disorders. The BMD response was comparable between these two treatments. Zoledronic acid should be considered as a treatment of choice in this patient population, given the much shorter duration of infusion. Long-term follow-up study is needed to confirm safety and efficacy in fracture reduction and prevention.