Joint Thrust Manipulation
Suggested Theories and Background
Benefits
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Joint thrust manipulation is used to restore normal range of movement, relieve pain and reduce muscle
spasm
The mechanisms by which this occurs are complicated and often disputed
Pain Gate Theory
 Mechanoreceptors within the joint capsule and spinal ligaments are stimulated by the tension created by a
joint trust manipulation
 This inhibits the nociceptor afferent input to the ascending pathways at the spinal cord
 This often causes a reflex muscle spasm to reduce also increasing joint range of movement
Periaqueductal Grey Area
 The periaqueductal grey area of the brain control analgesia
 Thrust manipulation stimulus activates the descending pain inhibitory system from the periaqueductal grey
area to the spinal cord
 Thrust manipulation immediately excites the sympathetic nervous system through mechanical nociception
releasing non-opioid pain relief
 After 20-45 mins sympathetic inhibition occurs resulting in opioids being released
Synovial Folds, Plicae and Impaction of articular cartilage
 Acutely ‘locked’ zygapophyseal joints can be due to entrapment of synovial folds, trapped plicae or articular
cartilage tearing and becoming trapped
 These structures will irritate the joint capsule, which is well innervated, causing pain
 Thrust manipulation can gap the joint surfaces allowing any trapped structure to return to its normal resting
position, relieving the irritation of the joint capsule
Minor Adhesions
 As soft tissue heals adhesions can form in the early stages of repair
 When tissue is loaded quickly it is stiffer than when loaded slowly
 The quick stress applied during thrust manipulation will concentrate the force of scar tissue and adhesions
causing an ‘abrupt alteration’
Cavitation
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During thrust manipulation the pressure within the joint cavity decreases
This leads to gases within the synovial fluid to pass into the joint cavity
As the gas moves it creates a bubble
It moves from an area of high pressure to low pressure
Once the ‘bubble’ reaches the joint cavity the pressure equalizes
This causes the bubble to collapse or explode causing a click or popping sound
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The gases are then slowly reabsorbed back into the synovial fluid over a period of time called the ‘refractory
period’
Cavitation is thought to increase the joint space, however studies have showed that changes in joint space
are achieved after thrust manipulation regardless of the presence of cavitation
Cavitation can have a powerful placebo effect as patients ‘hear’ something that means they should now be
better
Alternatively, they may ‘hear’ something that has made things worse
Procedure
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In order to perform thrust manipulations knowledge of coupling motions and joint locking are required
In order to perform spinal joint locking a combination of movements are needed opposite to the coupling
motions that naturally occur
The joints surrounding the treated level should be locked, to minimise the movement that occurs at other
levels
In order to produce a cavitation the target level should NEVER be locked
However research has shown that it is difficult to isolate specific levels
Coupling
Coupling refers to a movement at a joint that occurs in combination with a different movement around a separate
axis. Coupling occurs at all joints throughout the spinal column except the atlanto-axial joint.
Coupling can be categorised into 3, depending on ‘Fryette’s Law’
Law 1 – Neutral side bending produces rotation to the other side.
Law 2- Non Neutral rotation and side bending go to the same side
Law 3- Introducing motion in one vertebral joint in one plane automatically reduces its mobility in the other two
planes
Coupling - Cervical Spine
C0- C1
 Rotation and lateral flexion occur to opposite sides.
C1-C2
 There is currently a discrepancy within the literature as to the coupling that occurs here.
C2- C7
 Rotation and lateral flexion occur to the same sides.
Spinal Locking
Spinal locking is necessary when performing long-level high-velocity low-amplitude (HVLA) thrusts. In order to do
this the spine must be placed in a position opposite to its normal coupling behaviour.
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Spinal Locking- Cervical Spine
C2-C7
 Locking is achieved with cervical rotation and side bending to opposite sides.
Indications
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Clinical Prediction Rules can be used to help identify those who have a high probability of improvement from
cervical manipulation
3 from the following 4 criteria gives a 90% probability of a successful outcome with cervical manipulation
o Symptoms less than 38 days in duration
o Positive expectation that manipulation will help
o Side to side difference of 10° or more during cervical rotation
o Pain with poster anterior spring testing of the middle cervical spine
Contraindications
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Although there are many reasons why thrust manipulation should be performed, there are also reasons why
alternative methods may be chosen
The benefit from thrust manipulation must ALWAYS outweigh the perceived risk
If ever in doubt, DO NOT perform thrust manipulation
A cervical screen should always be performed following the guidance given by IFOMPT
Absolute
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Bone: any pathology that has led to significant bone weakening:
o Tumour, e.g. cancer
o Infection, e.g. TB
o Metabolic, e.g. osteomalacia
o Congenital, e.g. dysplasias
o Latrogenic, e.g. Long-term steroids
o Inflammatory, e.g. severe rheumatoid arthritis
o Traumatic, e.g. fracture
Neurological
o Cervical myelopathy
o Cord compression
o Cauda equina compression
o Nerve root compression with increasing neurological deficit
Vascular
o Signs of cervical artery dysfunction
o Aortic aneurysm
o Haemophilia
Lack of Diagnosis
Lack of consent
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Relative
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Adverse reaction to previous thrust manipulation
Disc herniation or prolapse
Pregnancy
Spondylolysis
Spondylolithesis
Osteoporosis
Anticoagulant/long term steroids
Advanced degenerative joint disease and spondylosis
Vertigo
Arterial calcification
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