title: Variability of forces applied by experienced physiotherapists during provocation of the sacroiliac joint.
abstract: OBJECTIVE
  To evaluate the distribution of total force vector and force components intended for the right and left sacroiliac joint, respectively, during pain-provocation sacroiliac joint tests.
  
  
  METHODS
  Two force plates, each capable of sensing three orthogonal forces, were used in a descriptive study to assess force.
  
  
  BACKGROUND
  Studies evaluating the reliability of sacroiliac joint tests have revealed conflicting results and to our knowledge, no studies have evaluated the distribution of forces and their variations.
  
  
  METHODS
  Fifteen physiotherapists, experienced in musculoskeletal therapy, performed the distraction test and pressure on apex sacralis on the same healthy person on two occasions.
  
  
  RESULTS
  In both tests, the total force vector was less on the force plate closer to the physiotherapist. The vertical force component dominated and was considerably greater than the lateral (examined person supine/prone). The caudal/cranial force component was small. Systematic differences were found for the total force vector and for the lateral and vertical force components between occasions and/or between the force plates.
  
  
  CONCLUSIONS
  The consistency of total force vector and force components was incomplete within and between physiotherapists and between occasions. Relevance. The results indicate that forces have to be investigated as the questions still arise of whether the variation in force distribution has any importance in pain response, whether force registration could be a useful pain evaluation instrument, and whether force registration could be a step towards standardising pain-provocation sacroiliac joint tests.
authors.affiliation: Department of Physical Therapy, Karolinska Institutet, 141 57, Huddinge, Sweden. ulla.levin@gym.ki.se
authors.forename: U
authors.initials: U
authors.lastname: Levin
authors.forename: L
authors.initials: L
authors.lastname: Nilsson-Wikmar
authors.forename: K
authors.initials: K
authors.lastname: Harms-Ringdahl
authors.forename: C H
authors.initials: CH
authors.lastname: Stenström
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001416:Back Pain / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D026741:Physical Therapy Modalities / Q000379:methods* / Q000592:standards*; D011312:Pressure; D012446:Sacroiliac Joint / Q000502:physiology*