High-velocity, Low-amplitude (HVLA) Thrust
A high-velocity, low-amplitude (HVLA) Thrust is a spinal manipulation technique used by chiropractors to force dislocated joints in the body back into their proper position. Though this medical term is a bit of a mouthful, we will break it down so that you may understand its terminology. High-velocity means that the manipulation is done quickly and forcefully. The patient gradually oriented into a position in preparation for the body movement to be made, and then the movement is done rapidly and forcefully.
The actually adjustment taken place in well under a second. Low-amplitude means that the part of the body that is moved during the adjustment is only moved a very short distance. The HVLA thrust is generally designed to treat neck pain; mid-back and low back pain, though other joint conditions outside the spine may respond to these types of treatments.
There are variations of the HVLA technique that are used to treat orthopedic problems such as whiplash-associated disorders, cervicogenic (neck-related) headaches, and Sacro-iliac joint dysfunction. The most common High-velocity, Low-amplitude (HVLA) Thrust that are used in chiropractic offices include the Diversified Technique, Gonstead Adjustment, and Thompson Terminal Point (or Drop) technique.
Diversified Technique: This type of spinal manipulation is the one that is most commonly used in chiropractic offices. In this technique, the therapist applied a fast (high-velocity) short (low amplitude) thrust to the patient's body to restore the function of a restricted joint. The goal of the technique is to improve mobility and stability in the restricted joint. Though the actually movement often takes place in a split second, the patient may be slowly rotated into a position that allows the manipulator to optimize the adjustment of the joint. While the forceful powerful thrust is being done, the patient may feel a crunch from within their spine and hear an audible "crack" or "pop". This movement, though somewhat scary the first time, should not be painful, and the sound you hear is simple gasses from the joint being released as shifts back into its proper alignment.
Gonstead Technique: This manipulation system is sometimes referred to as the Palmer-Gonstead Technique. This like the Diversified Technique, though there are some differences in how the chiropractor located the problematic joints that are restricted and the source of the patient's pain. There are also differences in the way that the patient is positioned in preparation for the short-lever high-velocity thrusts. The chiropractor may use custom designed tables and chairs that are specifically designed position the patient in such as way as the optimize the adjustment. The chest-knee table and the cervical chair are two examples of pieces of equipment that are specifically designed for use with the Gonstead Technique.
Thompson Terminal Point (or Drop) Technique: This technique involves the use of tables with sections that move or drop to facilitate the movement of the joint. The drop of the table alone may be used to facilitate the movement, or it may be used simultaneously with the traditional HVLA thrust to treat the problematic joint. Here, the traditional "cracking sound" may or may not be heard. For this reason, it is considered a milder form of manipulation and a more gentle approach.
Do I have to hear the cracking sound to known that the spinal manipulation was successful? Is the audible pop necessary? Those are two common questions that are asked. The actual "popping" sound emitted by your body during these techniques is known as cavitation. Cavitation is caused by the release of gasses that are released when the joint is pushed a short distance past its passive range of motion. This is the same process that occurs when you crack your knuckles. Many osteopathic and chiropractic clinicians do consider the cracking sound necessary in determining that the joint moved enough for adequate treatment, though there is no empirical clinic evidence supporting this belief.