Measurement of accessory motion: critical issues and related concepts.

The term "manual therapy" has traditionally been associated with physical therapists who examine and treat patients who have disorders related to the musculoskeletal system. In addition to using instruments to collect patient data, these therapists use a large variety of manually applied examination procedures. Range-of-motion tests, manual muscle tests, neurological tests, and palpation tests are just a few of the categories of tests these therapists use as part of the clinical decision-making process. The major sources of error that can affect the usefulness of manually obtained measurements are discussed. The literature that provides the theoretical and clinical bases for the assessment of joint surface movement is thoroughly reviewed. Conclusions are made about what is currently known about the usefulness of accessory motion tests. Suggestions are made for future research needs in order to clarify and enhance the usefulness of accessory motion tests and other examination procedures used by manual therapists.