The overall objective of this study is to define an effective therapeutic approach, using currently available medication, to prevent or mitigate the loss of bone mass and bone strength that occurs after acute spinal cord injury.

This is a randomized, double-blind placebo-controlled study of zoledronic acid to evaluate its efficacy and safety over a 2 year period for the prevention of bone loss and maintenance of bone strength in individuals with recent onset SCI (see diagram below). Subjects will be randomized at the baseline visit to receive either zoledronic acid or placebo. At the end of the first year of the study, each treatment group will be re-randomized to either zoledronic acid or placebo to evaluate the durability of response to zoledronic acid and the utility of serum bone markers to guide therapeutic decision making. DXA imaging, CT imaging and bone markers will be obtained at baseline, 3 months, 6 months, 12 months, 18 months and 24 months.

Inclusion Criteria:

• In-patient at Rehabilitation Institute of Chicago (RIC) or an outpatient who was recently discharged from RIC
• Males and females
• Age >/=18 years
• Medically stable in the opinion of subject's physiatrist
• SCI at within 120 days inclusive at time of screening
• SCI with inability to ambulate independently
• ASIA Impairment Scale (AIS) A, B, or C, at time of study entry
• Capable of positioning to have DXA performed
• Able to tolerate acetaminophen
• No known endocrinopathies (diabetes type 1 or 2 can be included)
• Normal TSH levels
• Normal 25-OH vitamin D levels (>/= 20 ng/ml) at baseline (subjects may be repleted)
• Normal calcium levels
• Normal renal function (creatinine <2.0 mg/dl)
• Well hydrated with adequate intake of liquids
• Able to return for all follow-up visits
• Capable of reading and understanding informed consent document
• Males and females of childbearing potential must be willing and able to use double barrier method of contraception for 2 months after having received study drug

Exclusion Criteria:

• Have Paget's disease of the bone
• Malignancy as a cause of acute SCI
• Have unexplained high levels of alkaline phosphatase in blood
• Any active gastrointestinal condition that results in malabsorption
• Poor dental hygiene or requirement for invasive dental procedure within two months prior to enrollment
• History of bone metastasis and skeletal malignancies
• History of alcoholism or drug abuse within the 2 years prior to study screening
• Other medical conditions that in the opinion of the investigator would preclude the subject from completing the study
• Elevated liver function tests >2x normal
• Currently being prescribed anti-convulsants at a dose or frequency that is determined to interfere with bone metabolism as determined by the investigator
• Currently being prescribed glucocorticoids, other than inhaled glucocorticoids
• Current or recent use any bone-active agents, including any bisphosphonate, raloxifene, hormone therapy (estrogen and estrogen/progestin), calcitonin or strontium-containing compounds within 60 days of screening.
• Pregnant, planning to become pregnant, or lactating

Baseline - 12 month visit

Adverse event collection began at the baseline visit, as soon as the participant received the first year study drug infusion. At each study visit, participants were asked about any changes to their health.

The number of participants in the trial was limited, particularly during the second year in each subgroup. Additionally, the number of women studied was limited but was representative of the general sex distribution observed in people with spinal cord injury.