A system and method is disclosed herein for measuring bone slope or tilt of a prepared bone surface of the muscular-skeletal system. The system comprises a three-axis accelerometer for measuring position, rotation, and tilt. In one embodiment, the three-axis accelerometer can be housed in a prosthetic component that couples to a prepared bone surface. The system further includes a remote system for receiving, processing, and displaying quantitative measurements from one or more sensors. A bone is placed in extension. The three-axis accelerometer is referenced to a bone landmark of the bone when the bone is in extension. The three-axis accelerometer is then coupled to the prepared bone surface with the bone in extension. The slope or tilt of the bone surface is measured. In the example, the slope or tilt of the bone surface corresponds to at least one surface of the prosthetic component attached thereto.