What is manipulation? A new definition

Definitions are important in healthcare. Unfortunately, problems can be found withall existing definitions of manipulation. This paper derives a set of eligibility criteria from prior definitions of manipulation to inform what should (and should not) be incorporated within a valid definition. These criteria were then used to select components from currently available empirical data to create a new definition. The resulting definition of manipulation is: "Separation (gapping) of opposing articular surfaces of a synovial joint, caused by a force applied perpendicularly to those articular surfaces, that results in cavitation within the synovial fluid of that joint." The corresponding definition for the mechanical response of a manipulation is: "Separation (gapping) of opposing articular surfaces of a synovial joint that results in cavitation within the synovial fluid of that joint." In turn, the action of a manipulation can be defined as: "A force applied perpendicularly to the articular surfaces." We believe these definitions to be valid (derived from and consistent with all available empirical data), complete (containing all necessary components), minimally sufficient (minimal redundancy, and sufficient to distinguish manipulation from other physical interventions), and robust (able to withstand important limitations embodied within sensible eligibility criteria). It is hoped that the simplicity and clarity of these definitions, and the transparency of their formation, will encourage their wide adoption in clinical, research, educational and professional settings.