Subacromial Injection of High Volume Versus Conventional Steroid Injection Guided by Ultrasound in Shoulder Pain. Randomized Controlled Trial

Shoulder pain is a common complaint in patients of all ages and activity levels, it is estimated that approximately 50% of the general population will experience at least one episode of shoulder pain over the course of a year. Shoulder pain has a general prevalence of 6.9-34%. The shoulder is the part of the upper extremity which is formed the proximal humerus, by the clavicle and the scapula, consisting in the shoulder griddle. The acromion is a bony process in the upper region of the scapula that articulates medially with the clavicle creating the acromioclavicular joint, at the same time forms the upper part of the shoulder joint. Between the humeral head and the acromion arch there is a space, the subacromial space, in which there are important structures for the proper functioning of the shoulder, among them, the subacromial bursa, the tendon of the rotator cuff and the tendon of the biceps brachii. The shoulder is the most mobile joint of all the body, therefore it is predisposed to suffer multiple injuries, including shoulder impingement syndrome, which has become one of the most frequent alterations of the musculoskeletal system. This pathology has an estimated prevalence of 43.7%. It is one of the most common causes of shoulder pain in the middle and advanced age patients.

Shoulder Impingement Syndrome is a condition in which structures in the subacromial space are chronically trapped between the humeral head and the acromion. It encompasses multiple conditions which includes partial rupture of the rotator cuff, rotator cuff tendinosis, calcified tendinitis or subacromial bursitis. All of these conditions may have a similar clinical picture and may be distinguishable by imaging of arthroscopy. The etiology of the syndrome is multifactorial, divided into extrinsic factors such as tendon overload, post trauma or repetitive microtraumas and intrinsic factors such as the vascularity of the tendon. There are also structural factors: anatomy of the acromion, subacromial osteophytes and acromioclavicular osteophytes; and functional factors: weakness of the rotator cuff, altered movement of scapula and ligament laxity increased. It is the result of a reduced space below the acromion. The most frequent clinical presentation will be insidious pain that can be installed in a period of days to months or after a trauma that can be irradiated to the side of the humerus. Usually the pain is nocturnal exacerbated by movements above the head or sleep on the affected shoulder and is attenuated by keeping the affected limb at rest.

Physical examination should assess muscular strength and ranges of motion. The general inspection should assess the presence of antalgic positions, muscular atrophy, asymmetries or sings of local inflammation. There is specific evidence for the evaluation of this pathology: Jobe's test, to evaluate de supraspinatus muscle, in which the patient is asked to perform 90° shoulder flexion, 30° abduction and external rotation and maintain the position against the shoulder resistance; Hawkins-Kennedy sign, for the subacromial impingement evaluation, with shoulder and elbow with 90° flexion perform rapid internal rotation of the shoulder, it is positive if it arouses with pain; Neer maneuver, for assessment of subacromial impingement, consists of the passive elevation of the extremity in abduction, flexion and internal rotation with stabilization of the scapula; Yocum´s maneuver, for assessment of subacromial impingement, the patient is asked to place the hand of the explored side in the contralateral shoulder and rises against resistance, it is positive if it causes pain. There are multiple differential diagnoses of this pathology, among which is adhesive capsulitis, cervical radiculopathy, glenohumeral instability, and acromioclavicular or glenohumeral osteoarthritis, among others.

The diagnosis is clinical and it is corroborated by imaging studies. Shoulder radiographs should be ordered in two positions to assess the morphology of the shoulder joint, to observe the distance between the humeral head to the acromion (11-14mm) and the evaluation of the acromioclavicular joint. Magnetic resonance imaging is the study of choice for evaluating shoulder impingement syndrome, where we will observe soft tissue structures that are part of the shoulder joint. Shoulder Impingement Syndrome is a pathology that causes pain and limitations to perform activities of daily living and evidence suggests that this condition is no self-limited, for this there are different alternatives of treatment. The aim of treatment is to decrease the pain and inflammation of soft tissues involved in the impingement in the subacromial space. Conservative treatment includes physical therapy, non-steroidal anti-inflammatory analgesics (NSAIDs) and subacromial infiltration. Surgical treatment includes shoulder arthroscopy to perform acromioplasty and thus release the subacromial space

Conservative Treatment