Shoulder pain is second only to back pain for visits to a doctor. The good thing is that evidence-based chiropractors are uniquely positioned to treat shoulder dysfunction better and faster than any other health care professional. Not because we are gurus, but because the research supports our approach. Manual therapy, ADL advice, joint manipulation, and specific rehabilitation are proven methods to reduce shoulder pain. Tissue injury and the resultant pain are consequences of sustained compression or repetitive stress to sub-acromial structures in nearly all shoulder pathologies. Two primary factors resulting in tissue injury are:
Nearly 100% of non-traumatic shoulder pain is due to these two factors!
The glenohumeral joint is designed to have significant ranges in all three planes of motion. Unfortunately, increased mobility comes at the expense of stability. The head of the humerus is a round structure contacting the minimally concave surface of the glenoid. Normal scapulohumeral motion maintains the humeral center of rotation directly above the concave scapular glenoid throughout the shoulders range of motion. This integrated motion between the scapula and humerus provides efficient function and joint stability. When this rhythm is disrupted by abnormal scapular motion, the resulting disproportionate humeral shift creates increased stress on the shoulder capsule and rotator cuff.
Scapular Dyskinesis leads to Shoulder Impingement creating Rotator Cuff Tendinopathy and resultant Rotator Cuff Tears
Rotator cuff dysfunction is now considered more degenerative than inflammatory– wherein a typical inflammatory reaction is histologically absent. Instead, there is degenerated and disorganized collagen fibers; signs associated with a failed healing response. Rotator cuff tendon degeneration may precede impingement in a self-perpetuating cycle of dysfunction. The process starts when an insult damages the tendon and leads to tendon degeneration. This weakens the tendon and diminishes its ability to oppose superior shearing force produced by the deltoid during arm abduction. The tendon becomes impinged, producing further insult. As tendon fibers fail, the enduring fibers remain under tension, thereby increasing the load and likelihood of failure.
Stress to the coracoacromial ligament (CAL) due to uncontrolled superior migration of the humeral head also results in calcification. The coracoid and acromion act as a roof the humerus. That’s right, type II and III acromions occur secondary to glenohumeral instability. Surgery to remove the acromion results in poor long-term outcomes as this further destabilizes the shoulder.
Function precedes structure until ultimately structure determines function. Wang et al. (2019) found increased coracoacromial ligament deformation and thickening of the supraspinatus in an overhead athlete population secondary to shoulder instability.
Shoulder pain is one of the most common presentations in a chiropractic office. This malady is responsible for nearly 5 million physician visits each year. Contrary to public opinion, there is no rotator cuff fairy that randomly taps a patient on the shoulder with lasting gifts of dysfunction and pain. Years of repetitive strain, sports, traumas, and poor posture are the primary contributors to shoulder dysfunction. Rotator cuff problems almost always begin with scapular dyskinesis, then anterior impingement syndrome, and eventually progress to rotator cuff syndrome if the causative factors are not corrected. This degenerative cascade affects the shoulder in a very predictable pattern. The only variable is the date at which the patient develops symptoms. Luckily there is ONE critical contributor that all chiropractors can address in the treatment of shoulder pain.
Yamamoto et al. (2015) studied a cohort of 525 participants without shoulder pain. Then, using ultrasound, his team identified those patients with asymptomatic rotator cuff tears; 24.5% showed a tear in one shoulder, and 11.9% had tears in both. (1) Yamamoto then subdivided this population into four groups based on their postural classifications as defined by Kendall.
(2) The researchers correlated each posture to the likelihood of rotator cuff tear and found that postural abnormalities are an independent predictor of rotator cuff tears.
“Prevalence of rotator cuff tears was 2.9% with ideal alignment, 65.8% with kyphotic-lordotic posture, 54.3% with flat-back posture, and 48.9% with sway-back posture. Logistic regression analysis identified increased age, abnormal posture, and past pain as factors associated with rotator cuff tears. It is difficult to conclude whether postural change represents a primary or secondary phenomenon due to rotator cuff tear. However, patients with ideal posture experience rotator cuff tears relatively rarely, so keeping the spine in ideal alignment would appear helpful as a measure for preventing rotator cuff tears as well as in rehabilitation therapy for shoulder disorders.” (1)
Based on our understanding of scapular mechanics and upper crossed syndrome, it is logical to conclude that posture is a risk factor for developing rotator cuff tears. This paper demonstrates the importance of correcting posture in four steps:
Cliff Atwell, B.S., D.C.