Researchers have noted an association between crepitus (audible tissue and joint noises) and posterior spinal joint deterioration. There may also be an association between increased joint stiffness and subtle crepitus. While previous studies have found a link between cavitation and increased vertebral mobility after spinal manipulations, a new study 1 examines the link between inaudible and audible lumbar crepitus and spinal manipulative therapy (SMT).
Noises associated with biochemical structures and mechanisms may indicate the existence of stress adhesions in the connective tissues surrounding the zygapophyseal (Z) joints. Lower back pain (LBP) patients may have more muscle tension, which can contribute to the compression of the articular surfaces in the Z joints, leading to greater crepitus. The process of SMT may assist in breaking up the adhesions and allow for freer (and silent) movement of the joints.
Ten male and female subjects between the ages of 18-65 years –five healthy, and five who suffered from lower back pain—participated in the study, which was approved by the National University of Health Sciences IRB. There were strict inclusion and exclusion criteria which ensured the healthy patients had no recent history of LBP, and the LBP patients had experienced recent and debilitating LBP but had not had spinal surgery or been diagnosed with disc degeneration or other serious spinal pathologies in the past.
For the purposes of comparison and research on the relative efficacy of methods in future studies, the subjects of both groups were fitted with several strategically-placed accelerometers and microphones, which were taped along the midline and on either side of the spine. Recordings of sound data occurring prior to, during, and after SMT were then displayed on a computer-based oscilloscope.
The study participants were led though a series of motions, including: flexion, extension, left and right lateral flexion, and left and right axial rotation. Both groups then received side-posture lumbar SMT on each side, and audible and subtle data was recorded after SMT.
Two highly qualified observers analyzed the recordings and noted each incidence of crepitus, as well as the precise location and amplitude of its occurrence. They also paid attention to any deviances between the two recording methods.
The results of the study indicated that crepitus is more common in those suffering from LBP than in people with no history of lumbar pain and that the audible and subtle sounds of crepitus increase incrementally as patients age. SMT significantly decreases crepitus, which indicates the measurement could, with further study, be considered a reliable measure of the effect of SMT on Z joint function. There was insignificant deviance between the data collected via accelerometers and microphones, though the microphones did pick up audible sounds that may have been caused by external interference, which suggests that the use of accelerometers alone may be considered an efficient means of collecting data in future studies. Due to the limited scope of this study, its authors suggest future studies should be conducted on a larger population to determine the overall relevance of crepitus as a means of therapeutic measure.