A study 1 of 100 individuals indicates most spinal patients have false beliefs regarding cavitation sounds during spinal manipulation and that those incorrect beliefs can inhibit patient wellness when the patient either refuses potentially beneficial spinal manipulation or develops the nocebo effect when no sound is produced during a procedure. The study, which examined typical beliefs regarding the cracking sounds that frequently occur during high-velocity low-amplitude (HVLA) thrust spinal manipulation, determined that healthcare providers who practice spinal manipulation could benefit their patients by educating them regarding the processes behind cavitation sounds and their degree of importance as regards to successful manipulation outcomes.
About Cavitation and Spinal Manipulation
When a practitioner uses HVLA to push a spinal joint beyond its usual range of motion, they are using a spinal manipulation technique that is ancient (first recorded by Hippocrates in 400 BCE) and widely-used today to treat back pain. Though many studies have been conducted as to the efficacy and safety of the procedure and the origin and results of the frequently-associated cavitation sounds that may occur during spinal manipulation, few studies have been conducted on how beliefs about cavitation may affect the outcome of a patient’s spinal care.
The cracking sounds associated with cavitation occur as the result of the drop of pressure when a mechanical adjustment creates a vacuum within a joint, resulting in the creation of a cavity within synovial fluid. Historically, the unstable bubble was thought to collapse shortly after its formation, but more recent research in PLOS One returned the origin of the sound from the cavity formation. Unfounded beliefs about the nature of the cavitation sounds may lead patients to resist spinal manipulation therapy or contribute to the nocebo effect when the sounds do not occur during therapy.
Patient volunteers were recruited via social media, advertising campaigns, hospitals, and connections to the investigators. In all, 100 individuals participated in the study—60 with no prior history of spinal manipulation and 40 with prior history of the procedure. Of the 60 with no prior history of spinal manipulation, 40 were asymptomatic at the time of the study, and 20 were experiencing nonspecific spinal pain. Of the 40 patients who had previously experienced spinal manipulations, half were experiencing spinal pain at the time of the study, and half were asymptomatic. All 100 volunteer patients completed a questionnaire and an in-person interview to determine their beliefs about cavitation sounds and their origin and effects on spinal manipulation. The mean age of the study participants was 43.5 years.
Results and Conclusion
Roughly half of the volunteer participants believed that the cavitation noises were a result of vertebral repositioning. Nearly one quarter of the volunteers ascribed the noises to vertebral friction. Only 9 percent of the study’s participants correctly assumed that the cavitation sounds were created due to a release of gas during manipulation. Forty percent of the participants assumed (incorrectly) that the cavitation noises were integral to a successful procedure and that no sounds were indicative of a failed procedure. The belief statistics were similar across both groups of participants—those with a history of spinal manipulation procedures, and those with no history of HVLA. Further, the study results suggest that most spinal patients perceive the spine as a fragile, unstable entity that may be subject to damage as the result of spinal manipulation and associated cavitation sounds. Because they may be more likely to resist treatment or experience the nocebo effect when the cracking sounds are not audible during treatment, it would be beneficial for spinal practitioners and physicians to educate their patients about cavitation noises and the process of spinal manipulation prior to treatment.