Chiro.Org Blog:

Has the hypomobile manipulable joint lesion been demonstrated to exist? Historically the manipulable joint lesion has, from the beginning of the chiropractic profession, been described as a painful stiff joint. [1, 2] Joint stiffness, commonly called hypomobility (also known in the chiropractic profession as “fixation”) has become by consensus one of the most important aspects of the manipulable joint lesion in the professions of chiropractic, osteopathy, and manual medicine. [3, 4] Nearly 100 years of clinical agreement between three separate professions supports the existence of such a lesion although research now supports its existence.