flaccid paralysis with progression of spine Ridaforolimus changes and evidence of central cord necrosis on MRI. AA remained tetraplegic with incomplete C3 involvement and needed long term ventilatory support. He had ASIA Class C injury and GMFCS level V function. He was totally dependent on his mother for activities of daily living and used a power wheelchair. AA sustained an atraumatic fragility fracture of the surgical neck of right humerus aged 9.5 years, 1.4 years after the initial spinal cord injury. The cause of the fracture was unknown, being detected during investigation of right shoulder swelling. The initial investigations revealed hypercalciuria with normal serum calcium and 25 hydroxyvitamin D levels. Bone turnover markers osteocalcin and deoxypyridinoline:creatinine ratio were raised .
Renal ultrasound showed no evidence Syk Inhibitors of nephrocalcinosis. Bone mineral density as determined by dual energy x ray absorptiometry and peripheral quantitative computed tomography showed osteoporosis. DXA was performed using a GE Lunar Prodigy and measurements were analysed using software version 8.6. The DXA value conversion to age matched Z scores were based on previously published normative data using an expanded dataset and updated software version 4.7. The total body bone mineral content for lean tissue mass was calculated on the basis of previously published normative data. These ancillary variables help to explain the aetiology of bone mineral content and bone mineral density measurements, especially in paediatric population when both bone and body size changes dramatically during growth.
pQCT was performed using a Stratec XCT 2000 and measurements were pericardium analysed using software version 6.0B. The 4% and 66% sites from the distal articular surface of the right tibia, and the 4% and 65% sites from the distal articular surface of the left radius were measured. This represents the metaphysis and diaphysis compartment of the bones. The pQCT value conversion to age matched Z scores were based on published paediatric reference data. Bone densitometry data at the start of treatment showed marked reduction in bone mineral content and bone mineral density compared to measurements taken 16 months earlier. AA was started on intravenous zoledronic acid one month after the fracture. The initial dose was 0.0125 mg/kg in 50 mls of normal saline infused over 30 minutes.
Second dose was 0.0375 mg/kg six weeks later and subsequent doses were 0.05 mg/kg six monthly. He received oral prednisolone 1 mg/kg during the first infusion to minimize acute phase reaction as he was prone to autonomic dystonia from noxious stimuli. He tolerated the infusion well with no fever and his calcium level remained in the normal range. AA sustained no further fractures after starting zoledronic acid. After 18 months of treatment, urinary calcium:creatinine ratio normalised and mineral homeostasis remained stable. Both bone formation and bone resorption markers reduced with treatment . Bone densitometry data at 16 months before treatment , baseline at start of treatment and 18 months after treatment are shown in Table 2. DXA data showed an improvement in total body and lumbar spine BMD and BMC, and an improvement in total body bone area for height. The increase in BMCLTM suggested that this increase was not due to an improvement in lean tissue mass but rather an effect of zoledronic acid treatment. pQCT data also showed a reversal in bone loss with improvement.