Apparatus and method for injecting fluent material at a distracted tissue site

A system and method is provided for distracting opposite surfaces from the interior of a bone, such as a vertebral body. A working channel cannula provides a working channel through which an inserter and an injection cannula can simultaneously pass. The inserter transports a plurality of wafers into the interior of the bone to form a load-bearing stack bearing against the opposite surfaces. The injection cannula is used to inject a fluent material into and/or around the stack. In certain embodiments, the fluent material is a load-bearing or hardenable material, such as bone cement. In other embodiments, the fluent material can be a BMP, HAP, or other osteo-inductive, osteo-conductive, or pharmaceutical compositions. A syringe containing the fluent material is engaged to the injection cannula and is operable to inject the fluent material into the vertebral body under controlled pressure.