Acromial spur: relationship to aging and morphologic changes in the rotator cuff.
Shoulder injuries are common in both young, athletic people and the aging population. the result of impingement syndrome and age related changes within the rotator cuff Impingement caused by bone spurs on the acromion is common in older .. with a rotator cuff tear and continue to function without pain or disability. J Shoulder Elbow Surg. Nov-Dec;14(6) Acromial spur: relationship to aging and morphologic changes in the rotator cuff. Ogawa K(1), Yoshida A. Disability of the Arm, Shoulder and Hand. .. association between acromion shape and the severity of rotator cuff pathology Also large subacromial spurs, thickening or . whether the changes in tendons are primarily the result of aging or a.
After the initial phase of elevation in the scapular plane or frontal plane abduction, the humeral head remains somewhat centered on the glenoid cavity with fluctuations between inferior and superior translations of typically less than 1 mm. Anterior humeral head translations in the magnitude of 2—5 mm have been demonstrated during passive glenohumeral flexion. During active glenohumeral flexion, anterior humeral head translation of less than 1 mm occurs over the course of motion.
Changes of this space occur in subjects with healthy shoulders; a decrease in the width of the acromio-humeral interval and an increase in the contact between the inferior acromion and underlying subacromial tissues occurs during glenohumeral abduction.
Contact pressure and force in the subacromial space has also been demonstrated to increase during glenohumeral abduction.
Theoretically, these changes in the subacromial space would be accentuated with an increase in the normal superior and anterior humeral head translation, leading to mechanical compression of the tissues in subacromial space during glenohumeral motion.
This articulation is assessed kinematically either two-dimensionally or three-dimensionally. The joint is typically described with five degrees of freedom, three rotations and two translations. The three-dimensional analysis of scapular motion by van der Helm and Pronk describe scapular upward rotation occurring about an anterior-posterior axis, with the inferior angle of the scapula moving laterally; 10 external rotation occurring about a superior-inferior axis, with the lateral border of the scapula moving posteriorly; posterior tilt occurring about a mediallateral axis, with the inferior angle moving anteriorly.
Less well examined are scapular translations, depicted as scapular positions. Scapular positions can be represented by clavicular rotations about the sternoclavicular joint in two different planes: The assumption is made that motion of the clavicle at the sternoclavicular joint will be in direct relationship to scapular translation, because of the interposed rigid bone clavicle between these two joints and the lack of significant motion occurring at the acromioclavicular joint.
During glenohumeral elevation the clavicle retracts posteriorly and elevates, putting the scapula in essentially a more superior and posterior position. Weak or dysfunctional scapular musculature, fatigue of the infraspinatus and teres minor and changes in thoracic and cervical spine posture have all demonstrated a change in scapular kinematics. Mechanisms of rotator cuff RC tendinopathy have been classically described as extrinsic, intrinsic or a combination of both.
Intrinsic impingement, theorizes that partial or full thickness tendon tears occur as a result of the degenerative process that occurs over time with overuse, tension overload, or trauma of the tendons. Although internal impingement can be considered an extrinsic mechanism, narrowing of the subacromial space is not a hallmark finding. The acromiohumeral distance AHDa linear measure between the acromion and the humeral head used to quantify the subacromial space, has been studied in patients with RC disease using magnetic resonance imaging, 13 ultrasonography, 14 and radiographs.
It is reduced in SAIS patients with the muscles at rest or during muscle activation which functionally narrow the subacromial space. Furthermore, AHD less than 7 mm with the arm at rest is a predictive indicator of less favorable surgical outcome. Significant relationships have been demonstrated between acromion morphology and patient's self reported shoulder function and the severity of the rotator cuff pathology.
This suggests that direct encroachment of the subacromial space by the coracoacromial arch soft tissue or bony changes is not the only mechanism of impingement. Supporting this theory of a requisite overuse exposure, symptomatic RC disease is more often present in dominant than nondominant shoulders. These include shortening of the posterior-inferior glenohumeral joint capsule and decreased RC muscle performance.
When posterior capsular tightness was surgically induced in cadavers, there was an in increase in superior and anterior humeral head translations during passive glenohumeral flexion. Excessive superior and anterior humeral head translations can decrease the size of the subacromial space, leading to increased mechanical compression of the subacromial structures. Furthermore, stretching to address impairments of posterior shoulder tightness has been identified as an important component to rehabilitation for patients with RC tendinopathy.
Excessive superior translation of the humeral head resulting from rotator cuff weakness can lead to a decrease in the subacromial space during elevation, and thus increased mechanical compression of the subacromial contents. The pain is typically localized to the anterolateral acromion and frequently radiates to the lateral mid-humerus.
Patients usually complain of pain at night, exacerbated by lying on the involved shoulder, or sleeping with the arm overhead. Normal daily activities such as combing one's hair or reaching up into a cupboard become painful. Weakness and stiffness may also be encountered, but they are usually secondary to pain. In their meta-analysis, Hegedus et al.
Imaging Standard radiographs including internal and external rotation anteroposterior, scapular Y, axillary, and Supraspinatus outlet views are important for the thorough evaluation of shoulder pain. These plain radiographs may show characteristic changes of rotator cuff disease, including subacromial osteophytes,subacromial sclerosis, cystic changes of the greater tuberosity, and narrowing of the acromiohumeral distance, they are not definitive.
Ossification of the coracoacromial ligament CAL or presence of a subacromial spur can be best identified in the sagittal oblique plane; however, differentiation of a pathologic spur and the normal CAL can be difficult.Arthroscopic Subacromial Decompression: Spur Removal
Typically, MRI is performed with the arm adducted; however, this position does not recreate the position of impingement. In the last decade, several systematic reviews on treatment for impingement syndrome were published. Hence, the conclusion on effectiveness of various treatments was primarily based on the combination of these outcome measures. There is strong evidence that extracorporeal shock-wave therapy is no more effective than placebo, 3233 moderate evidence that ultrasound therapy is no more effective than placebo, 34 and limited evidence that laser is no more effective than placebo with regard to functional limitations.
On the short term, arthroscopic acromioplasty is more effective than open acromioplasty with regard to functional limitations and return to work. However, moderate evidence exists that on the long term open and arthroscopic acromioplasty are equally effective with regard to functional limitations.
Evidence suggests that extrinsic, intrinsic, and combinations of biomechanical mechanisms play a role. There are no significant differences in outcome between conservatively and surgically treated patients with subacromial impingement syndrome. For most patients with SAIS, nonsurgical treatment is successful. Surgical intervention is successful in patients who fail nonsurgical treatment.
Surgeon experience and intraoperative assessment may guide the method of surgical treatment. Studies have shown that many surgical interventions, including debridement and open and arthroscopic acromioplasty, have been successful.
Rotator Cuff / Impingement
However, there remains a need for high-quality clinical research on the diagnosis and treatment of SAIS. Shoulder disorders in general practice: J Bone Joint Surg Am. Clin Orthop Relat Res. Anatomical and biomechanical mechanisms of subacromial impingement syndrome. Clin Biomech Bristol, Avon ; Glenohumeral elevation studied in three dimensions.
J Bone Joint Surg Br. Translations of the humerus in persons with shoulder impingement symptoms. J Orthop Sports Phys Ther. Translation of the glenohumeral joint with simulated active elevation. Excursion of the rotator cuff under the acromion. Patterns of subacromial contact.
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Am J Sports Med. Three-dimensional recording and description of motions of the shoulder mechanism. It is subject to the most pinching of all the rotator cuff muscles.
Rotator cuff tears can be the result of a traumatic injury or deterioration over time. Symptoms may be present, but in many cases, the patient experiences no symptoms at all. In young active people, full thickness rotator cuff tears are fairly uncommon. When they do occur, they are usually the result of a high-energy injury to the rotator cuff that is associated with throwing or overhead sporting activities. In older people, rotator cuff tears tend to be the result of wear and tear over time.
Shoulder Structure Bones and Joints The bones of the shoulder: The humerus is the upper arm bone. This is the "ball" of the shoulder's "ball and socket" joint. The scapula is the flat, triangular bone commonly called the shoulder blade. Prominent areas of the scapula serve as attachment points for many muscles and ligaments.
The glenoid is the shallow "socket" on the side of the scapula that receives the 'ball' of the humerus. Together they form the "ball and socket" arrangement of the shoulder. The scapular spine is a horizontal ridge along the back of the scapula that divides the scapula into upper and lower regions. The acromion is the end of the scapular spine. It projects up to form the top of the shoulder. The coracoid process is a projection towards the front of the scapula and is an attachment site for several muscles and ligaments.
The clavicle is the collarbone. Although it appears to be straight, it actually forms an S-shape when seen from above. Although the ribs do not physically attach to the scapula, the thorax stabilizes and maintains proper positioning of the scapula so that the arm can function to its fullest capacity. Additionally, there are four bone junctions, or joints: The glenohumeral joint is the main joint of the shoulder.
Here, the glenoid on the scapula and the head of the humerus come together. Because of its poor fit, this joint relies heavily on the surrounding soft tissue for support. The acromioclavicular joint, or AC joint, is the bony point on the top of the shoulder.
It stabilizes the scapula to the chest, by connecting the acromion on the scapula to the clavicle, or "collarbone". A thick disk of fibrocartilage acts as a shock absorber between the two bones.
The surrounding capsule and ligaments give this joint great stability. The sternoclavicular joint, or SC joint, connects the other end of the clavicle to the sternum, or "breastbone".
Like the AC joint, this joint contains a fibrocartilage disk that helps the bones achieve a better fit.
It also gets excellent support from its joint capsule and surrounding ligaments. The scapulothoracic articulation is the area where the scapula, embedded in muscle, glides over the thoracic rib cage. The surrounding muscles and ligaments keep the scapula properly positioned so that the arm can move correctly.
Cartilage There are two types of cartilage in the shoulder: Articular cartilage is the shiny white coating that covers the end of the humeral head and lines the inside surface of the glenoid. It has two purposes: To provide a smooth, slick surface for easy movement To be a shock absorber and protect the underlying bone Fibrocartilage is the thick tissue that forms the disks of the AC and SC joints and the labrum, the ring that deepens the glenoid.
Fibrocartilage has three roles: To act as a cushion in shock absorption To help stabilize the joint by improving the fit of the bones To act as a spacer and improve contact between the articular cartilage surfaces Ligaments The shoulder relies heavily on ligaments for support. Ligaments attach bone to bone and provide the "static" stability in a joint. Ligaments will alternately become tight and loose with normal motion.
They keep the joint within the normal limits of movement. The glenohumeral ligaments attach in layers from the glenoid labrum to form the joint capsule around the head of the humerus. The coracoacromial arch is the group of ligaments that spans the bony projections of the coracoid process and the acromion. The coracoclavicular ligaments and the acromioclavicular ligament provide most of the support for the AC joint.
Muscles and Tendons Muscles and tendons work together in the shoulder to provide the "dynamic" stability of the shoulder. There are four muscle groups in the shoulder: The rotator cuff muscles are the subscapularis, the supraspinatus, the infraspinatus, and the teres minor.
They are the primary stabilizers that hold the "ball" of the humerus to the glenoid "socket". The socket is too shallow to offer much security for the humerus. These four muscles form a "cuff" around the humeral head, securing it firmly in the socket. As its name implies, this group of muscles also rotates the arm. The rotator cuff protects the glenohumeral joint from dislocation, allowing the large muscles that control the shoulder to power the arm with great mobility.
The biceps tendon complex also helps keep the humeral head in the glenoid and helps raise the arm. The scapulothoracic muscles attach the scapula to the thorax. Their main function is to stabilize the scapula to allow for proper shoulder motion. The superficial muscles of the shoulder are the large, powerful outer layer of muscles that are important to the overall function of the shoulder. This group includes the deltoid muscle, which covers the rotator cuff muscles.
Bursae A bursa is a pillow-like sac filled with a small amount of fluid. Bursae plural reduce friction and allow smooth gliding between two firm structures, like bone and tendon or bone and muscle. There are over 50 bursae in the human body; the largest is the subacromial bursa under the acromion in the shoulder. The subacromial bursa and the subdeltoid bursa under the deltoid muscle are often considered as one structure.
This bursa separates the rotator cuff and the deltoid muscle, from the acromion. Symptoms What are the signs and symptoms of impingement syndrome?
Most often the onset of symptoms is related to an episode of overuse. In many patients, the episode occurred some time in the past and the shoulder has failed to return to normal. Impingement symptoms are marked by pain: The pain is sharp and intermittent in its early stages.
As impingement progresses, the pain becomes more of a constant ache. Although pain is usually present after impingement sets in, the original event that led to the problem is often relatively minor and not remembered as painful.
Once inflammation starts, simple movements may become painful. Overhead motions tend to increase the pain. There is less space for the bursa when the arm in this position, causing more compression on the bursa. Arm movements at waist level are not painful. In this position, there is more space for the bursa, and therefore it is less compressed. Pain usually increases at night for two reasons.
First, inflammation and swelling tend to get worse as the shoulder is used during the day, and this can lead to more pain in the evening. Second, the mind is usually less occupied in the evening, allowing pain to become a major focus of attention.
What are the signs and symptoms of a rotator cuff tear? The symptoms of a rotator cuff tear are very similar to those of impingement syndrome with the added complaint of weakness. This weakness will vary depending on which rotator cuff tendon has been torn.
For example, if the supraspinatus muscle is involved as is most often the case weakness will be present with forward arm elevation and overhead activity. Many patients are at first unaware of how much strength they have lost when they tear the rotator cuff.
Diagnosis How are impingement and rotator cuff tears diagnosed? With a careful history and physical examination, impingement and rotator cuff tears can be easily diagnosed in the doctor's office. Further testing may be necessary to determine the exact nature of a rotator cuff tear. After the evaluation of symptoms, the doctor will perform certain muscle tests to determine whether there are tears in the rotator cuff tendons and to rule out other conditions.
The doctor may place the arm in positions that reproduce the described pain to confirm the diagnosis. There are many tests that can isolate specific areas of pain and weakness to help make the diagnosis.
WSIAT | Shoulder Injury and Disability
Further evaluation may include: A diagnostic injection can help the doctor distinguish between impingement syndrome and a full thickness rotator cuff tear. A local anesthetic is injected into the inflamed bursae to eliminate the pain. If strength in the shoulder returns once the pain is blocked, it is likely that the weakness was due to pain and the rotator cuff tendons are not torn.
A rotator cuff tear is suspected if strength does not return while the pain is blocked. X-rays can reveal signs of arthritis, fractures, and bone spurs on the acromion. They can also reveal changes in position of the humerus and scapula that may suggest a rotator cuff tear. These images are frequently negative in the early stages of injury since X-rays show bone structure but not soft tissue.
An arthrogram is another method used to help diagnose a rotator cuff tear. A dye is injected into the shoulder and X-rays are made. If a tear in the rotator cuff tendons exists, the dye will run through the tear and make it visible on X-ray.
Ultrasound may also be used to diagnose a tear; however, results with this technology are difficult to evaluate and are very dependent on the skills of the technician and radiologist.
Treatment How are impingement and rotator cuff tears treated? Impingement and rotator cuff tears can be treated non-operatively or with surgery. Treatment for both injuries usually begins with a non-operative treatment plan.
These results are lower in older patients and in those with large bone spurs. When trauma causes a tear in younger patients, surgery is often the first choice of treatment.