Efficacy of manual therapy.

The use of manual therapy to treat somatic pain syndromes and associated disabilities is widespread. Yet, the efficacy of manual therapy has not been previously established because equivocal findings in the literature prevent definitive conclusions. The purposes of this article are (1) to establish objective criteria for judging the validity of manual therapy research, (2) to identify and discuss the results of those trials that were determined to be valid demonstrations of treatment efficacy or valid demonstrations of nonuseful therapy, and (3) to determine whether patients who benefit from manual therapy have common characteristics. The abstracts or full reports of 146 titles with appropriate key words were reviewed. Of these, 105 studies were not primary studies of manual therapy and were thus eliminated from review. In the 41 remaining studies, 18 did not utilize statistical comparisons or report blinded assessment of outcome measures. Nine controlled studies yielded negative results, but the statistical power or minimum sample size required to detect potential differences between manual therapy and control groups was not described. The 14 studies that met the efficacy criteria were categorized by the following factors: (1) the anatomical region of intervention, (2) pragmatic versus explanatory goals, and (3) primary intervention (manipulation, mobilization, combination). There was a paucity of valid explanatory research in all areas and a particular absence of controlled trials involving manual therapy applied to the peripheral joints. Manual therapy for low back pain, however, was studied extensively. The analysis of valid trials provided clear evidence that manual therapy, particularly manipulation, can be an effective modality when used to treat patients who have low back pain. A preliminary "profile" of the patient with low back pain who would likely benefit from manual therapy included acute symptom onset with less than a 1-month duration of symptoms, central or paravertebral pain distribution, no previous exposure to spinal manipulation, and no pending litigation or workers' compensation. Suggestions for future manual therapy research are discussed.