A surgical guidance system for properly orienting a surgical instrument, such as an acetabular cup inserter, within a patient relative to a plurality of anatomical reference points includes a support device for retaining the patient, a reference sensor fixedly coupled to the support device and a tool sensor removably coupled to the instrument. The support device includes a plurality of abutment pads that directly contact the plurality of anatomical reference points. A processor is electrically connected to the reference and tool sensors and is programmed to collect spatial orientation data compiled from each sensor. Using the spatial orientation data, the processor determines in real-time the actual orientation of the surgical instrument relative to the anatomical reference points. An indicator is electrically connected to the processor and provides a feedback signal that assists the surgeon in properly orienting the instrument relative to a user-defined acceptable range.