David I Graber, Dc, DACBSP
I frequently get asked some common questions from Chiropractors about chiropractic adjustments and adjusting technique. Here are a few of them with answers from both the research, discussions with noted experts in the field, and my own experience.
Q: Does there need to be an audible cavitation to have a successful adjustment?
The audible release from a high velocity low amplitude (HVLA) adjustment is caused by a cavitation process whereby a sudden decrease in intracapsular pressure causes dissolved gasses in the synovial fluid to be released into the joint cavity.
Cavitation is not essential for the effects of a HVLA impulse, or thrust adjustment. Most of the beneficial mechanical and neurological effects occur with or without an audible release. HVLA adjustments produce similar effects on the autonomic nervous system and hypoalgesia with or without a perceived audible response.
Joint separation & gapping occur with and without cavitation occurring. Cavitation indicates joint separation, but doesn’t indicate how much it separates. More muscle tightness around joints adjusted, the use of more long-lever techniques, and faster application tend to produce more cavitation upon gapping.
Maximal mechanoreceptor stimulation occurs at the end ranges of joint movement and the effects may be mutually exclusive to the goal of cavitation with a manipulation.
That being said, HVLA adjustments that produce cavitation do have a few specific additional effects.
Spinal manipulation (SMT) that produces an audible response immediately down regulates the gain (decreases the sensitivity) of muscle spindles of the paraspinal muscles via the 1a reflex pathway. This results in a decrease in muscle hypertonicity and muscle spasm.
Joint gapping is larger when performing SMT when a “cracking” sound occurs.
Patients have reported that manipulations with cavitation were experienced by patients as ampler, faster, more precise, and more successful.
It’s important to note that when cavitation does occur, it almost always involves multiple joints rather than a single one, even when the contact and manipulation is specific to a segment.
In my experience, the focus required to gain a specific cavitation from an adjustment produces a cleaner more effective technique, and better results. However, getting a synovial symphony is secondary to good technique application.
Q: What are the best techniques for adjusting the cervical spine?
It’s important that doctors have several technique options to use with a particular patient. There is no one technique suitable for all patients. Choosing a technique to use for a particular patient involves the doctor’s technical expertise, the condition or pathology of the joints, the phase of injury, the patient’s sensitivity to touch and positioning, and the neurological response desired.
Research into different chiropractic techniques have shown that electromechanical adjusting instruments deliver the fastest impulse, followed by spring loaded instruments like the activator. The fastest manual technique is the toggle recoil. The greatest force is delivered by the toggle recoil, followed by both the Gonstead seated technique and the diversified supine lateral break.
For patients with a significant cervical kyphosis, prone techniques are preferable to supine.
In regards to manual cervical distraction techniques (MCD), most studies have been done utilizing non-thrust techniques. To date, there is no data on the effects of more aggressive cervical distraction thrust techniques commonly seen on YouTube videos.
Chiropractors using MCD have demonstrated fair to good proficiency in delivering prescribed traction forces while doing the procedure. Cox prone MCD has been shown to reduce intradiscal pressure in cadaveric specimens.
Q: Is there a difference adjusting the Thoracic spine prone (P-A) or supine (A-P)?
Studies on force delivery with thoracic spinal manipulations (TSM) show that supine or A-P TSM produces more Z-axis force than prone or P-A TSM. The direction of the force with A-P TSM tends to be vertical (ceiling to floor) even if the therapist adjusts the angle of the subject’s spine.
Prone P-A TSM distributes more Y-axis (cephalad-caudal) force than A-P TSM. In young asymptomatic individuals, the forces delivered are greater at the patient-table interface (anterior surface) than at the patient-doctor interface (posterior contact). However, in older adults’ thoracic spines, these findings were reversed with forces greater at the patient-doctor interface than the patient-table interface.
Regional Interdependence: Forces imparted to thoracic spine during high-velocity low-amplitude spinal manipulative therapy were transmitted to the cervical spine.
Q: Are there any types of patients that respond better to adjustments than others?
There are several characteristics that have been found in good responders to SMT. Some of these are:
Spinal Segmental Stiffness: Patients with at least one hypomobile vertebral segment, or spinal segmental stiffness beyond normal respond better to HVLA thrust manipulation.
Multifidus Activation: Patients with increased activation and recruitment of the multifidi after SMT have been shown to be good responders to SMT
Minimal Facet Joint Degeneration: In lumbar spine back pain patients, SMT responders tended to have a lower prevalence of severely degenerated facets than non-responders.
More Localized Symptoms: Patients with lumbar pain and no symptoms extending distal to the knee have been shown to be better responders to SMT. Patients with cervical pain with referral proximal to the shoulder or those with cervical spondylosis without radiculopathy have been shown to respond better to SMT.
Shorter Duration of Symptoms: Spinal pain symptom duration of less than 30 days for cervical, and 16 days for lumbar spine pain conditions have a better immediate response to SMT.
Early Symptomatic Response to SMT: Acute neck pain patients (<4 weeks symptoms) that reported improvement in 1 week, and chronic neck pain (>12 weeks symptoms) reporting improvement in 1 month had greater improvement. Acute low back pain patients respond better than chronic low back pain patients. Low back pain patients respond better if at least 1 hip has more than 35 degrees of internal rotation. Predictors of improvement in Thoracic spine pain were a greater decrease in both pain intensity and tenderness.
Patients who respond poorly to SMT most often have one or more factors as the reason: Inappropriate technique used, poorly executed technique, an unsuitable patient was selected, and the condition was not appropriate for the technique or treatment.
*References available upon request
About the Author:
Dr. David Graber is nationally known presenter on chiropractic technique and is a member of the ANJC board of directors. He maintains a private practice in Parsippany, NJ. He blogs on chiropractic and clinical topics at: drgraber.wordpress.com. He can be reached at: DrDavidGraber@gmail.com.
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