High Velocity Low Amplitude Thrust (HVLAT)

Spinal manipulation or High Velocity Low Amplitude Thrust (HVLAT) is commonly used by Chiropractors, PTs and some MDs. HVLAT is shown to produce therapeutic benefits that are biomechanical, muscular reflexogenic, and neurophysiological in nature1.

Biomechanical effects of HVLAT are gapping in facet joints2. Distraction in the joint causes cavitation, which increases joint space. Therefore, it increases overall available range in the joints. In the RCT (n=16) by Cranmer et al2, MRI results showed an average change in joint separation of +1.2 mm for the manipulation group, an average change of +0.3 mm in the control group. Lehman and McGill3 were able to demonstrate increased ROM in all planes post HVLAT in a single subject case study. Three-dimensional spine kinematics and trunk muscle EMGs were assessed during a variety of tasks performed by a professional golfer exhibiting non-specific, chronic, low back pain. After HVLAT, an increase in all three axes of motion during a golf swing, with concomitant muscle responses were observed.

The reflexogenic effect is thought to produce a reflex reduction in pain and muscle hypertonicity; therefore, ceasing the pain-muscle spasm-pain cycle. In the case of an injury or dysfunction, there is an increase in gamma motor neuron activity, decrease in the stimulation threshold for the alpha motor neuron, hypertonicity in muscles and facilitated spinal stretch reflexes. In those patients with the most pain, the amplitude of the reflex response is significantly larger4. HVLAT can cause increased joint mobility by producing a barrage of impulses, which silence the facilitated gamma motor neurons1, breaking the pain-muscle spasm-pain cycle. The Indahl et al.5study demonstrated that distension of the facet joint decreased muscle activation in the paraspinal muscles measured on EMG. The stretch of the facet joint capsule caused excitation of an inhibitory interneuron, which inhibited alpha motor neuron activation. Potter et al.1 noted a decrease in EMG activity to a painful segment, post-HVLAT, but this did not occur at a non-painful control segment. These studies provide some evidence that spinal manipulation can alter the neurophysiological control of the paraspinal muscles.

Manipulation may alter pain perception by modulation of the pain gate mechanism or by stimulating the release of neurotransmitters. By facilitating facet joint mechanoreceptors and large diameter Aβ afferents from muscle spindles, HVLAT may modulate the pain gate mechanism in the dorsal root1. Substance P is a neurotransmitter released from dorsal horn of the spinal cord and facilitates the central transmission of nociceptive input.  endorphins exert their anti-nociceptive influence by decreasing the effectiveness of substance P in the dorsal horn, thereby decreasing afferent nociceptive input to higher centers8. The study by Vernon et al.,6 an increase in  endorphins was noted in HVLAT group compared to the control who received a sham manipulation.

Each state has different allowances in manipulation done by PTs defined in state practice acts. Washington and Arkansas are the only states that prohibit physical therapists from performing spinal manipulation by statute7. This prohibition in Washington is the result of negotiations with the State chiropractic group, in which the Physical Therapy Practice Act was revised to gain direct access in the late 1980’s8. There is not a specific event that led to a ban in Arkansas.

Even though PT manipulation has been challenged by chiropractors for a long time, there are no current unresolved disputes. In 2006, in the Teston v. Arkansas State Board of Chiropractic Examiners case, Michael Teston, PT, was fined ten thousand dollars for performing spinal manipulations on two patients. The Arkansas State Board of Physical Therapy, the American Physical Therapy Association, and the Federation of State Boards of Physical Therapy found the treatments to be “within the scope of the practice of physical therapy” and asked the Supreme Court of Arkansas to overturn the decision of the Arkansas State Board of Chiropractic Examiners. However, their appeal was rejected9.

Another dispute took place on January 20, 2012 in Alabama and was presented to the Supreme Court. The state chiropractic board attempted to prohibit James Dunning, DPT from advertising and performing spinal manipulations.  The Supreme Court of Alabama rejected this attempt10.

NJ became a direct access state in 200311; however, the state practice act does not clearly state if PTs can perform manipulations or not12. NY has been a direct access state since 200613. On NY State Education website, mobilizations & manipulations are listed under PT interventions14. However, NY state education law article 136 mentions mobilization but does not include manipulation15.

References

1. Potter L, McCarthy C, Oldham J. Physiologic Effects of Spinal Manipulation: A Review of Proposed Theories. Phys Ther Rev 2005; 10: 163–170.

2. Cramer GD, Tuck NR, Knudsen JT, Fonda SD. Effects of side posture positioning and side posture adjusting on the lumbar zygapophysial joints as evaluated by magnetic resonance imaging: a before and after study with randomization. J Manipul Physiol Therap 2000;23: 380–394.

3. Lehman GJ, McGill SM. The influence of a chiropractic manipulation on lumbar kinematics and electromyography during simple and complex tasks: a case study. J Manipul Physiol Therap 1999;22:576–581.

4. Colloca CJ, Keller TS. Electromyographic reflex responses to mechanical force, manually assisted spinal manipulative therapy. Spine 2001;26:1117–1124.

5. Indahl A, Kaigle A, Reikeras O, Holm S. Interaction between the porcine lumbar intervertebral disc, zygapophysial joints and paraspinal muscles. Spine 1997;22:2834–2840.

6. Vernon HT, Dhami MS, Howley TP, Annett R. Spinal manipulation and beta-endorphin: a controlled study of the effect of a spinal manipulation on plasma beta-endorphin levels in normal males. J Manipul Physiol Therap 1986;9:115–123.

7. Physical Therapy Association of Washington. Talking Points for Manipulation. Available at: http://www.ptwa.org/pdfs_misc/ManipulationTalkingPoints_01_10.pdf. Accessed September 17, 2012.

8. Coppersmith Orthopedic & Sports Physical Therapy Blog. Stumping for Physical Therapy. February 14, 2011. Available at: http://cospt.wordpress.com/2011/02/ Accessed September 18, 2012.

9. International Chiropractors Association. ICA files major brief in landmark Arkansas Chiropractic Board vs. PT Case. Available at: http://www.chiropractic.org/index.php?p=news/landmarkptbrief. Accessed on September 14, 2012.

10.Bishop D, Longnecker L. PT Wins High Court Ruling. Advance for Physical Therapy & Rehab Medicine. 2012. Available at: http://physical-therapy.advanceweb.com/Features/Articles/PT-Wins-High-Court-Ruling.aspx Accessed September 18, 2012.

11. Advance for Physical Therapy & Rehab Medicine. New Jersey Becomes 36th State to Achieve Direct Access. 2003. Available at: http://physical-therapy.advanceweb.com/Article/New-Jersey-Becomes-36th-State-to-Achieve-Direct-Access.aspx. Accessed September 18, 2012.

12. NJ Consumer Affairs. Chapter 39A -State Board of Physical Therapy. 2006. Available at: http://www.njconsumeraffairs.gov/laws/ptregs.pdf Accessed on September 16, 2012.

13. NY State Education Website. Physical Therapy Frequently Asked Practice Questions. 2012. Available at: http://www.op.nysed.gov/prof/pt/ptfaq.htm. Accessed September 15, 2012.

14. NY State Education Website. Physical Therapy. 2009. Available at: http://www.op.nysed.gov/prof/pt/. Accessed on September 18, 2012.

15. NY State Education Website. Physical Therapy. 2009. Available at: http://www.op.nysed.gov/prof/pt/article136.htm. Accessed September 20, 2012.

Information provided should not be used to diagnose a condition or pathology. Proper diagnoses require proper investigation in a healthcare setting by a healthcare provider. A pathology can be individualistic and circumstantial for each patient/client. We are here to provide information for guidance and direction only. Please consult with a physician or healthcare provider before attempting to initiate any of our suggestions.

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