Bone Abstracts

Background: Boys with muscular dystrophy as presented by Duchenne muscular dystrophy (DMD) lose muscle strength and are usually confined to a wheelchair until 13 years. Furthermore they often have development of myogenic scoliosis, and scoliosis surgery is necessary to acquire sitting balance. Osteoporosis is one of the major concerns to perform surgical treatment. Patients with DMD or congenital muscular dystrophy (CMD) have fragile bones due to loss of ambulation, glucocorticoid therapy and DMD itself.

Objects: To investigate BMD and bone metabolism in patients with muscular dystrophy and to verify efficacy and safety of preoperative bisphosphonate (BP) administration for osteoporosis associated with myogenic scoliosis.

Martials and methods: BMD and bone turnover markers were examined in 11 boys with muscular dystrophy who had underwent spinal surgery. A mean age was 14.5 years at surgery and all were non-ambulatory. BMD measurement was performed at lumbar spine (L2–4) and on total body. Patients were administered oral BP (Alendronate 35 mg) once a week, and BMD and bone turnover markers were measured before BP administration and before surgery.

Results: Mean lumbar BMD (L2–4) was 0.49 g/cm² (Z score: −4.5) and mean thoracic, lumbar and pelvic BMD measured by total body scan were 0.50, 0.57 and 0.46 g/cm², respectively. All patients had severe osteoporosis with extremely high bone turnover (mean bony alkaline phosphatase: 60.6 μg/l, TRACP5b: 928 mIU/l). Mean duration of BP administration was 5.3 months. All patients could continue the drug without any side effects. Preoperative BP administration revealed a significant increase of L2–4 BMD (6.4%) and a significant decrease of bone turnover markers.

Conclusion: Patients with muscular dystrophy had severe osteoporosis with high bone turnover and preoperative BP administration improves bone fragility. ormyogenic scoliosis.