Comparison of Mechanical Force of Manually Assisted Chiropractic Adjusting Instruments

Forces of Commonly Used Chiropractic Techniques for Children: A Review of the Literature

“…Activator instrument had lower minimal forces than previously reported by Colloca et al 22 Zegarra-Parodi et al 20 29 According to a recent osteopathic article, both chiropractic sacro-occipital and osteopathic craniosacral therapy techniques apply forces at below 1 N. 20…”

“…The specificity of any of the instruments measured is also unknown because the applicator tip on most of them is larger than most cervical vertebrae in an infant. 16,22 Considering all of this information, the application of the NMI, HAI, and each of the Activator II, IV, and V instruments to the cervical region of children younger than 3 months delivers a force less than the 50 N to 70 N 18 where medical spinal manipulation on children was recorded by Koch. In addition, the forces applied at the lowest settings of the Activator II and NMI were both at the 20 N range recommended by Marchand as a maximal safe limit for infants younger than 3 months 15 ; however, the Activator IV and V minimum settings transmit forces above the 20 N level recommended by Marchand for children below 3 months of age when applied directly to the cervical spine.…”

“…There have been 2 articles attempting to measure the forces applied by these and other instruments, with different measurement approaches resulting in different force readings (Fig 2). According to Colloca et al, 22 the mean minimum force applied by an Activator I is 61.5 N (Table 2), whereas the Activators II and III apply approximately 137.8 N and 128.2 N, respectively, and the Activator IV applies 123.1 N. 22 These values were measured by fixing the instruments to a stable surface and applying the tip directly to a metal force plate (Fig 2a). However, Liebschner et al 24 argue that the approach to applying and measuring force needs to be analogous to the way in which it is delivered to a human patient and so incorporated a range of polymorphous structures to replicate different levels of tissue stiffness in the human spine (Fig 2b).…”

“…The Harrison Adjusting Instrument (HAI) and the Neuromuscular Impulse (NMI) both offer electrically assisted mechanical handheld measured thrusts. The HAI is reported to give a minimum thrust of about 45 N into a fixed force plate on a hard surface 22 (Table 2) and the NMI a minimum of 20 N onto a soft tissue analog 24 (Fig 2; Table 2). As stated earlier, the Activator V is also mechanically loaded and is battery powered with a minimal force setting into a soft tissue analog of 40 N.…”

“…28 Sacro-occcipital Medical manipulation simulation on a force plate was higher than that estimated for modified manipulation by a chiropractor. 25 Colloca et al 22 Measurement of peak forces at each setting on the Activator instruments I, II, III, and IV. The HAI and NMI instruments were applied directly to a force plate.…”