As teriparatide is approved for up to 24 months of treatment in the US, patients will be given the option to continue in a 6-month extension phase upon completion of 18 months of teriparatide treatment. This extension will allow for collection of additional bone quality data. In Canada, the use of teriparatide is currently approved for 18 months. Patients in Canada may be given the opportunity to participate in the 6-month extension phase, contingent upon Health Canada approval of the use of teriparatide treatment for 24 months.