In a method for diagnosing or helping to diagnose a bone tissue condition of a patient, a portion of bone tissue of the patient is irradiated using a light source. The bone tissue may be irradiated in vivo through the skin or via an incision, for example. Alternatively, a biopsy of the bone tissue may be irradiated. Then, spectral content information for light scattered, reflected, or transmitted by the bone tissue is determined, and is used, at least in part, to determine whether the patient has a bone tissue condition.