In 1949, Steinbroker14 provided the first documentation of utilizing a pressure gauge to measure palpation forces for the purposes of physical diagnosis. The term “algometer,” however, wasn't coined until 1954 by Head and Keele.6 Algometers, sometimes referred to as "dolorimeters," "palpameters," "algesiometers," or "pressure threshold meters" are designed to quantify and document levels of tenderness via pressure threshold measurement and pain sensitivity via pain tolerance measurement. An algometer is essentially a very sensitive force gauge (mechanical or digital) designed to measure forces applied to very specific locations on the patient. Its tip generally ranges between .5cm2 and 2cm2. Results are typically reported in terms of pressure.
Pressure threshold is defined as the minimum pressure (force) required to cause pain. Pressure threshold measurements are usually performed over areas of muscle tenderness (sometimes referred to as trigger points). Normal data for male and females have been determined for many muscles in which trigger points are frequently found1. Side-to-side comparison is also of significance when evaluating the results of testing.1
Pressure tolerance is defined as the highest pressure (force) which can be tolerated under clinical conditions. Pressure tolerance measurements are typically performed over normal muscle and bone. Normal pressure tolerance data for males and females has been determined4.
Many clinical applications of the algometer have been documented, including evaluation of fibrositis12 and fibromyalgia16, identification of trigger points2, quantification of joint tenderness in arthritis conditions5,8,11, evaluation of pain sensitivity1,6, abdominal pain17, and in psychological research10. Pressure measurement has also been shown effective for evaluating the results of pain relieving modalities such as anesthetic blocks, heat, manipulation, anti-inflammatories, and for documenting the long-term effectiveness of treatment1,9. Because of its reliability and reproducibility, algometry can be used for objective medico-legal documentation of pain intensity3