Improving Shoulder Function and Pain With an HVLA Thrust
Mark Studin, DC, FPSC, FASBE(C), DAAPM
The shoulder has been reported to be the fifth most common cause of chronic pain.1 Subacromial pain syndrome (SAPS) is one of the most common causes of shoulder pain, with multiple etiologies and known to be a combination of rotator-cuff pathologies, such as tendonitis bursitis tendinopathies, and tears.2
Previously, there has been little knowledge of the natural history and treatment of SAPS, with the focus on treating inflammation through steroid injections and NSAIDs, although the presence of said inflammation has not been confirmed.3 All non-surgical interventions, including injections, medication, manual therapy, exercise, electrotherapy, and cognitive therapy as first-line management, remain unclear as to dose, type and load.4
The prognosis of SAPS is poor, with 40-50 percent of patients reporting pain 6-12 months after an initial consultation.5 With historical treatments remaining unclear, a thoracic spine low-amplitude, high-velocity thrust (manipulation or chiropractic spinal adjustment) immediately increases neuromuscular drive, and improves pain and function.6 When evaluating pain inhibition and increased function, this high-velocity low-amplitude thrust (HVLAT) mechanism shows a level of consistency in a physiological mechanism rendering positive outcomes.
An HVLAT involves gapping the zygapophyseal joints, reducing the impaction and opening the joint, encouraging the misplaced meniscoid (spacer) to return to its normal anatomical position in the joint cavity. With the meniscoid displaced, the articular cartilage buckles, forming a space-occupying lesion under the capsule, causing a meniscoid entrapment.
Many type 3 and type 4 nerve fibers (nociceptors) have been observed in the joint capsule and render central sensitization involving muscles spasms and resultant malfunction.7
It has also been reported that an HVLAT causes hypoalgesia and increased mechanical function in disparate regions through central sensitization.8-9 These mechanisms are intact in symptomatic and asymptomatic patients, and offer therapeutic answers to those in pain and those seeking increased function or strength.
The evidence of a thoracic spinal HVLAT leading to an immediate increase in muscle activity linked to short-term changes in reported shoulder pain is consistent with previous findings. So is the connection between an HVLAT and central sensitization as the neurological connection to cause and effect.6-7,10
References
Arias-BurÃa JL, et al. Ultrasound-guided percutaneous electrolysis and eccentric exercises for subacromial pain syndrome: a randomized clinical trial. Evid-Based Compl Alt Med, 2015 (2015).
Breivik H, et al. Survey of chronic pain in Europe: prevalence, impact on daily life, and treatment. Euro J Pain, 2006;10(4):287-333.
Coronado RA, et al. Changes in pain sensitivity following spinal manipulation: a systematic review and meta-analysis. J Electromyo Kinesiol, 2012;22(5):752-767.
Croft P, et al. The clinical course of shoulder pain: prospective cohort study in primary care. Primary Care Rheumatology Society Shoulder Study Group. BMJ, 1996;313(7057):601.
Dunning J, et al. Spinal manipulation and electrical dry needling in patients with subacromial pain syndrome: a multicenter randomized clinical trial. J Orthop Sports Phys Ther, 2021;51(2):72-81.
Evans DW. Mechanisms and effects of spinal high-velocity, low-amplitude thrust manipulation: previous theories. JMPT, 2002;25(4):251-262.
Gay CW, et al. Immediate changes after manual therapy in resting-state functional connectivity as measured by functional magnetic resonance imaging in participants with induced low back pain. JMPT, 2014;37(9):614-627.
Hegarty AK, et al. Evidence for increased neuromuscular drive following spinal manipulation in individuals with subacromial pain syndrome. Clin Biomech, 2021;90:105485.
Reed WR, et al. Paraspinal muscle spindle response to intervertebral fixation and segmental thrust level during spinal manipulation in an animal model. Spine, 2015;40(13):E752.
Seitz AL, et al. Mechanisms of rotator cuff tendinopathy: intrinsic, extrinsic, or both? Clin Biomech, 2011;26: 1-12.
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The most common condition affecting the shoulder is rotator-cuff disease. From acute tears to chronic tendinopathy, it’s common and needs a thorough workup. In fact, even asymptomatic shoulders can have full-thickness rotator-cuff rears in up to 40% of instances. Let’s look at additional conditions that can present to the office with weakness, loss of motion and pain in the shoulder beyond rotator-cuff tears.
