Vertebral fracture cascade progression in bisphosphonate treated DMD patient on chronic steroids.


Clinical Management

Poster Number: 15


Virginia Kaperick, MD, Medical College of Wisconsin, Children's Wisconsin

Our patient is a 13 year old with Duchenne Muscular Dystrophy (DMD) on chronic glucocorticoid therapy who presented with continued progression of vertebral fractures (VF) despite prior doses of bisphosphonates and estimated bone mineral density (BMD) within the normal range. He was diagnosed with DMD at age 6 ½ years and started initially on prednisone and later transitioned to Deflazacort weekend dosing after excessive weight gain. At age 10 years he was in the late ambulatory stage with obesity and increased falls. He reported falling twice on his “bottom” which resulted in persistent midline back pain. Early imaging studies demonstrated vertebral fractures at T9 and L2 with diffuse demineralization. Follow up imaging studies confirmed multiple VF and a DXA BMD z-score -1.2, with normal bone age. He was treated with zoledronic acid (0.025 mg/kg) x 2 doses with improvement of back pain and DXA BMD scores. At age 13 ½ years he was non-ambulatory and chronic back pain returned. X-rays indicated additional vertebral compression fractures consistent with vertebral fracture cascade. DXA BMD z-score was still in normal range. Zoledronic acid therapy (0.05 mg/kg) was restarted with improvement of pain. This case highlights importance of regular spine screening and importance of early initiation of bisphosphonate treatment, with plans to continue long term therapy in glucocorticoid treated DMD patients.

Learning Points to be included in poster:
1.Importance of regular vertebral fracture screening. Review of 2018 DMD guidelines.
2.Vertebral fractures often occur in DMD patients with normal bone density on DXA
3.Current expert recommendation is to treat with bisphosphonates at first sign of vertebral fracture and plan for long term treatment in DMD as underlying risk factors not anticipated to improve
4.Zoledronic acid provides pain relief from bone injury by blocking the nociceptive receptors