POSTURAL RELATIONSHIP WITH SHOULDER PAIN

 

POSTURAL RELATIONSHIP

A forward head posture and rounded shoulders can be common among healthy people who do not have physical ailments. Unfortunately, poor posture can also be a source of neck and shoulder pain. Normal postural alignment, starting from the external auditory meatus of the skull, allows a line of gravity to pass through the odontoid process, anterior to the axis of motion for flexion and extension of the occiput, posterior to the midcervical spine, through the glenohumeral joint, anterior to the thoracic and posterior to the lumbar spine In a person with good postural alignment, the arm lift can advance freely through a full 160 to 180 motion without compressing the soft tissues in the subacromial space. In the patient with classic forward head, rounded shoulders and increased thoracic kyphosis, the scapula rotates forward and downward, depressing the acromion process and changing the direction of the glenoid fossa. When the patient attempts to elevate the arm, the supraspinatus tendon or subdeltoid bursa can collide with the anterior portion of the acromion process. Repeated movements of this nature can accelerate overuse injury or cumulative trauma disorder (CTD) and can lead to early changes consistent with tendinosis or bursitis. At least one study found a significant relationship between severe thoracic kyphosis and interscapular pain, between forward head and interscapular pain, and between rounded shoulders and interscapular pain. Positions of sitting with the entire spine flexed result in high levels of electromyographic (EMG) activity in the neck and shoulder muscles. The activity of the neck and shoulder muscles is minimal in a sitting position of slight thoracolumbar extension with the cervical spine vertical. Upright postures associated with a forward head demonstrate an increase in cervical and lumbar lordosis and an increase in thoracic kyphosis. In addition, the forward head posture forces the midcervical spine into hyperextension, resulting in narrowing of the intervertebral foramina and increased load on the facet joints, especially in segments C4-5 and C5-6. This situation can lead to irritation of the C5 and C6 spinal nerve roots, respectively. It can also cause irritation of the dorsal C1 root, vertebral artery symptoms, or entrapment of the dorsal suprascapular and scapular nerves. Headache is a common consequence of chronic poor posture. One source of these headaches is increased stress on the C2-3 facet joints and associated intervertebral foramen. Headaches originating from the C2-3 facet joint or the C3 dorsal branch are quite common in patients with chronic neck pain and headache. The cervical facet joints are at risk due to the increased load tension found in the forward head posture. The articular cartilage, the synovial capsule and the meniscoid of the facet joints are exposed to persistent and recurrent trauma. This trauma can lead to arthritic changes and restrictions within the affected joints. Any injury or irritation to these articular facets contributes, through the damage of type I mechanoreceptors, to disorders involving the static postural reflexes of the spine and upper limbs. Finally, the intervertebral discs are put at risk due to the increase in the cut due to the increase in cervical lordosis. Normal lordosis of the cervical spine allows for an adequate balance of compressive forces with the cut. If the column were to straighten, the compressive forces would be greater and the shear forces at the discs would be reduced. Additional consequences of forward head posture are a shortening of the SCM, superior trapezius and scapula levator muscles resulting in scapula lift. The subsequent increase in thoracic kyphosis abducts the scapula and allows elongation of the rhomboid and lower trapezius muscles in association with a shortening of the serratus anterior. In addition, this posture causes a shortening of the dorsal, teres major, subscapularis and pectoralis major and minor muscles which pushes the humerus into a position of internal rotation. This posture alters the normal scapulohumeral rhythm and can cause impingement within the subacromial space (subdeltoid bursa, biceps tendon, or supraspinatus tendon) during arm elevation. An abducted scapula may have additional sequelae, such as increased compression of the acromioclavicular joint, a shortened conical ligament with an elongated trapezoidal ligament, and an anterior slide of the proximal clavicle resulting in shortening of the posterior capsule of the sternoclavicular joint. . Scoliosis also affects the postural relationship of the scapula to the spine. The scapula is elevated on the convex side and depressed on the concave side of scoliosis. The patient may also have a slight flutter on a rib hump secondary to ipsilateral rotation of the spine at that level. For example, left-sided flexion is usually accompanied by a rightward rotation of the upright thoracic spine, so that the right shoulder blade is raised and slightly flattened.

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