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What Does an Adjustment Do?
May 05, 2011 by Dr Matthew D. Long
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What Does an Adjustment Do?
May 05, 2011 by Dr Matthew D. Long
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What Does an Adjustment Do?
May 05, 2011 by Dr Matthew D. Long
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One of the most common questions that we are asked is, "What does an adjustment actually do?"
Every chiropractor would be aware of the most common theories regarding spinal manipulation and how it exerts its effects upon the human body. However, the detail is often somewhat sketchy. Fortunately the research literature is gradually building a body of evidence as to the mechanics of manual treatment and how it is transduced into neurological effects. Some of these seem well understood; the analgesic effects occurring at the dorsal horn, the increased sympathetic activity following mobilisation, changes in joint perception and proprioception, and altered patterns of muscle recruitment. We have discussed this last item recently, specifically the changes to multifidus muscle activity that arise following a spinal adjustment, and it has returned again as the subject of a new study published in Journal of Orthopaedic & Sports Physical Therapy...
There is increasing evidence that spinal joint dysfunction involves a loss of joint stability, most likely the consequence of reduced joint proprioception. The origin of this defect is not yet fully defined, but probably arises from a deficit in feedback from both articular mechanoreceptors and the muscle spindles of the intrinsic stabilisers of the spine. Indeed, it has been proposed widely that the multifidus muscles act in a sensory capacity just as much as an end-organ of stability. As such, any loss in multifidus size, tone or activity would most likely herald further joint problems down the track. This has prompted research into the tendency for the multifidus to atrophy following a back injury (within 36 hours in one study), and the loss of trunk/neck positional awareness and increased 'joint repositioning errors' that occur as a result. Clearly the multifidus is a prime target of research.
The question for us as clinicians, is “Can we alter multifidus function if it does atrophy?”
The answer seems to be “Yes”.
In the paper by Koppenhaver and colleagues (1) they used diagnostic ultrasound to measure the thickness of the lumbar multifidus muscles at specific segments. Subjects were then treated with spinal manipulation on two occasions within a one-week period and the muscle cross-sectional area was again measured. Study subjects showed an increase in muscle contraction and size compared to controls, which seemed to parallel their symptomatic improvement. The authors concluded that;
"Although we can only speculate on the physiologic mechanisms involved, the increased ability for patients to contract their LM after SMT may be due to either facilitation and/or disinhibition of the α-motor neuron system. These mechanisms may involve the peripheral nervous system, spinal cord, supraspinal nervous system, or more likely, may be due to multilevel and multisystem interactions."
So it appears that spinal manipulation may alter one of the prime deficits occurring in the spinal pain patient. And if it proves to be true that we can improve multifidus activity, then this suggests that greater joint proprioception (and therefore stability) might be the ultimate end-product. To my mind this goes some way towards justifying the use of manipulation in patients with chronic spinal conditions, in which 'instability' is probably a feature. Indeed, most conceptual models have relied upon a desire to target stiffened joints to improve mobility. But it just may well be that the real culprits are the mildly unstable, proprioceptively compromised joints that need adjustment. Perhaps the only reason that these segments feel stiffer than their neighbours is the reflex splinting of the longer strap muscles in an effort to provide support. We have discussed this previously in other blog posts. In this vein the authors of the study write;
"The results of this study may point towards opportunities to improve the clinical application of SMT. Traditionally, manipulative providers have often conceptualized the goals of SMT as correcting faulty structural alignment, reducing stiffness, and improving range of motion. Providers likely select co-interventions perceived to facilitate these goals, such as stretching and range of motion exercises, to accompany SMT. If the benefits of SMT are at least partially mediated by improved trunk muscle contraction, specifically of the LM (lumbar multifidus), modification of clinical protocols and co-intervention choices could improve outcomes."
Something to think about anyway...
Dr Matthew D. Long
BSc (Syd) M.Chiro (Macq)
Every chiropractor would be aware of the most common theories regarding spinal manipulation and how it exerts its effects upon the human body. However, the detail is often somewhat sketchy. Fortunately the research literature is gradually building a body of evidence as to the mechanics of manual treatment and how it is transduced into neurological effects. Some of these seem well understood; the analgesic effects occurring at the dorsal horn, the increased sympathetic activity following mobilisation, changes in joint perception and proprioception, and altered patterns of muscle recruitment. We have discussed this last item recently, specifically the changes to multifidus muscle activity that arise following a spinal adjustment, and it has returned again as the subject of a new study published in Journal of Orthopaedic & Sports Physical Therapy...
There is increasing evidence that spinal joint dysfunction involves a loss of joint stability, most likely the consequence of reduced joint proprioception. The origin of this defect is not yet fully defined, but probably arises from a deficit in feedback from both articular mechanoreceptors and the muscle spindles of the intrinsic stabilisers of the spine. Indeed, it has been proposed widely that the multifidus muscles act in a sensory capacity just as much as an end-organ of stability. As such, any loss in multifidus size, tone or activity would most likely herald further joint problems down the track. This has prompted research into the tendency for the multifidus to atrophy following a back injury (within 36 hours in one study), and the loss of trunk/neck positional awareness and increased 'joint repositioning errors' that occur as a result. Clearly the multifidus is a prime target of research.
The question for us as clinicians, is “Can we alter multifidus function if it does atrophy?”
The answer seems to be “Yes”.
In the paper by Koppenhaver and colleagues (1) they used diagnostic ultrasound to measure the thickness of the lumbar multifidus muscles at specific segments. Subjects were then treated with spinal manipulation on two occasions within a one-week period and the muscle cross-sectional area was again measured. Study subjects showed an increase in muscle contraction and size compared to controls, which seemed to parallel their symptomatic improvement. The authors concluded that;
"Although we can only speculate on the physiologic mechanisms involved, the increased ability for patients to contract their LM after SMT may be due to either facilitation and/or disinhibition of the α-motor neuron system. These mechanisms may involve the peripheral nervous system, spinal cord, supraspinal nervous system, or more likely, may be due to multilevel and multisystem interactions."
So it appears that spinal manipulation may alter one of the prime deficits occurring in the spinal pain patient. And if it proves to be true that we can improve multifidus activity, then this suggests that greater joint proprioception (and therefore stability) might be the ultimate end-product. To my mind this goes some way towards justifying the use of manipulation in patients with chronic spinal conditions, in which 'instability' is probably a feature. Indeed, most conceptual models have relied upon a desire to target stiffened joints to improve mobility. But it just may well be that the real culprits are the mildly unstable, proprioceptively compromised joints that need adjustment. Perhaps the only reason that these segments feel stiffer than their neighbours is the reflex splinting of the longer strap muscles in an effort to provide support. We have discussed this previously in other blog posts. In this vein the authors of the study write;
"The results of this study may point towards opportunities to improve the clinical application of SMT. Traditionally, manipulative providers have often conceptualized the goals of SMT as correcting faulty structural alignment, reducing stiffness, and improving range of motion. Providers likely select co-interventions perceived to facilitate these goals, such as stretching and range of motion exercises, to accompany SMT. If the benefits of SMT are at least partially mediated by improved trunk muscle contraction, specifically of the LM (lumbar multifidus), modification of clinical protocols and co-intervention choices could improve outcomes."
Something to think about anyway...
Dr Matthew D. Long
BSc (Syd) M.Chiro (Macq)
References:
1. Koppenhaver, S. L., Fritz, J. M., Hebert, J. J., Kawchuk, G. N., Childs, J. D., Parent, E. C., et al. (2011). Association between changes in abdominal and lumbar multifidus muscle thickness and clinical improvement after spinal manipulation. The Journal of Orthopaedic and Sports Physical Therapy, 41(6), 389–399. doi:10.2519/jospt.2011.3632
1. Koppenhaver, S. L., Fritz, J. M., Hebert, J. J., Kawchuk, G. N., Childs, J. D., Parent, E. C., et al. (2011). Association between changes in abdominal and lumbar multifidus muscle thickness and clinical improvement after spinal manipulation. The Journal of Orthopaedic and Sports Physical Therapy, 41(6), 389–399. doi:10.2519/jospt.2011.3632