A bone oximeter probe includes an elongated member and a sensor head at an end of the elongated member to make measurements for a bone. The measurements can indicate the viability or nonviability of the bone. In an implementation, the probe is advanced through an incision in soft tissue, towards the underlying bone, and positioned so that the sensor head faces the bone to be measured. Optical signals are sent from the sensor head and into the bone. The bone reflects some of the optical signals which are then detected so that measurements for the bone can be made. Some of these measurements include an oxygen saturation level value, and a total hemoglobin concentration value of the bone.