Supraspinatus muscle
Encyclopedia
The supraspinatus is a relatively small muscle of the upper arm that runs from the supraspinatous fossa
superior of the scapula
(shoulder blade) to the greater tubercle
of the humerus
. It is one of the four rotator cuff
muscles and also abducts
the arm at the shoulder. The spine of the scapula separates the supraspinatus muscle from the infraspinatus muscle
, which originates below the spine.
passes laterally beneath the cover of the acromion. Research in 1996 showed that the postero-lateral origin was more lateral than classically described.
of the humerus
.
The distal attachments of the three rotator cuff muscles that insert into the greater tubercle of the humerus can be abbreviated as SIT when viewed from superior to inferior (Supraspinatus, Infraspinatus, and Teres minor).
The acronym SITS regarding the rotator cuff muscles is completed by including the Subscapularis muscle, which unlike the other rotator cuff muscles attaches to the lesser tubercle
of the humerus.
(C5 and C6), which arises from the superior trunk of the brachial plexus
and passes laterally through the posterior triangle of the neck and through the scapular notch on the superior border of the scapula. After supplying fibers to the supraspinatus muscle, it supplies articular branches to the capsule of the shoulder joint.
This nerve can be damaged along its course in fractures of the overlying clavicle
, which can reduce the person’s ability to initiate the abduction
.
becomes increasingly more effective at abducting the arm and becomes the main propagator of this action.
The supraspinatus muscle is one of the musculotendinous support structures called the rotator cuff
that surround and enclose the shoulder
. It helps to resist the inferior gravitational forces placed across the shoulder joint due to the downward pull from the weight of the upper limb.
The supraspinatus also helps to stabilize the shoulder joint by keeping the head of the humerus firmly pressed medially against the glenoid fossa
of the scapula.
For USMLE step 1, know that the supraspinatus initiates abduction of the shoulder. Without a functioning supraspinatus, the physician must start abducting the patient's arm and eventually the patient will be able to finish abduction if the deltoid is functional, which is common because the supraspinatus is innervated by the suprascapular nerve from the superior/upper trunk of the brachial plexus. The deltoid is innervated more distally by the axillary nerve, which arises from the posterior cord of the brachial plexus.
contraction for more than one minute. From this study, it is suggested that the "true" action of the supraspinatus is to hold the capsule in position to allow greater functional strength and stamina of the deltoid muscle.
In addition a conventional radiography, with its good bone resolution, can give advices for potential risks, i.e. shape and declination of the acromion, open meta-meso-acromial or meso-basi-acromial apophysis gap with mobile acromion fragments, and so on; Or advices for already happened damaging events, i.e. raised stand of the humerus head with discontinuous Bandi line, cystic-erosive changes at the tuberculum majus and collum anatomicum humeri, sclerosis or entheso-pathological spurs at the acromion, and so on.
After positioning the applicator transversally to the supraspinatus tendon, the examinator has again to glide the applicator towards dorsal. The tendon should appear as an arched semiechogenious structure between the slightly echogenious musculus deltoideus and the strongly echogenious humerus head.
Orientation-aid for the longitudinal plane:
As an aid to orientation, it is advisable to begin the examination with the delineation of the acromion, as it is easy to palpate and its identifiable echo extinction. To adjust the longitudinal plane image the way it is known in the x-rays and the physical examination, the acromion has to be visible at the image border.
Orientation-aid for the transversal plane:
Again it is advantageous to start above the acromion and then move the transducer to the humerus. The acromion echo extinction disappears and the wheel-like figure with almost concentric projection of the deltoid muscle, supraspinatus muscle tendon and humeral head-outline turns up as soon as the transducer is directed perpendicularly and parallel to the acromion edge. Using the anterior transversal plane one can depict the intraarticular part of the long head of the biceps brachii muscle. Additionally one can use the posterior transversal plane to depict the intersection of the infraspinatus muscle tendon and the posterior edge of the fossa.
As in many cases, also at the supraspinatus tendon, anatomical subclinical alterations can be found which leads to MR images with seemingly damaged and to be adjusted tendons. In asymptomatic persons of course without any traumatic event Neumann C.H. et al. has found in 89% focal, linear, or diffuse increased signal intensity of the supraspinatus tendon with or without loss of the low-signal-intensity tendon margin on proton density-weighted images. This is why the group around Dr. Neumann claims that „increased signal intensity in the supraspinatus tendon on proton density-weighted images without a corresponding increase on T2-weighted images, the presence of small amounts of fluid in the subacromial space, and the lack of preservation of the subdeltoid fat plane are common findings in asymptomatic shoulders and by themselves are poor predictors of rotator cuff disease.“
Nakagaki K. et al dissected 76 shoulders in cadavers and has found in the group with a normal cuff, compared to this with tears, that not only the short diameter but also the long diameter of the slice of the supraspinatus muscle decreased in the length with increase of the cuff defect.
Kaick O. et al takes further steps in this direction and samples a striking new path by using the fact that supraspinatus tendon tears have an impact on the overall body of the muscle, i.e. retraction, atrophy. Through computer rendered MR images the three-dimensional shape of the overall body is calculable and made non-invasively visible. They confirm that this new method could in the future be an accurate alternative to the actual invasive diagnostic gold standard, the arthroscopy.
Regarding rotator cuff tears the supraspinatus muscle is by far the most affected. The rotator cuff tears involved the supraspinatus in 93% of cases, the subscapularis in 38%, and the infraspinatus in 24%. This increased frequency is based on the biomechanically stressful position between the acromion and acromio-clavicular joint above and the humeral head below.
It is known and well-established that ultrasonography reliably detects and quantifies supraspinatus tears. To examine the supraspinatus tendon optimally, it is important to position the patient correctly. Especially in the ultrasonographic investigation. So which position should be generally recommended? Ferri et al. compared the widespread Crass with the modified Crass position and has come to the conclusion that in the transversal plane both positions detected the supraspinatus tears with its correct size. On the other hand at the sagittal plane the modified Crass overestimated the tear size, and that’s why the classic Crass position should be adopted.
A to supraspinatus tears and MRI limited study of Schroeder et al. showed that the intravenous addition of contrast agent in T1-weighted imaging ameliorated significantly both the principal finding of a lesion and the differentiation between partial and full ruptures. Especially for lesions less than 1cm. Dr. Schroeders group declared following principal reasons for misinterpretation: The absence of contrast agent, motion artifacts, an expansion less than 1cm, the differentiation of pure degeneration without rupture of partial ruptures, the differentiation of partial ruptures with definite degeneration of complete ruptures and the detection of covered ruptures.
Atrophy & fatty degeneration:
Only by comparative bilateral observation of the undressed shoulders, a supraspinatus and or infraspinatus muscle atrophy attracts immediately attention. This alludes most probably to a subacromial impingement, and rarely also to a nerve paralysis.
In 1989 described Björkenheim et al. already the coherence between tendinous damage and muscular atrophy / fatty degeneration. He simulated severe complete rotator cuff tears in rabbits by removing their tendon. After losing the physiological traction stress signals the muscle begins to degenerate.
For a best possible prognosis of the anatomical and functional outcome after an operative rotator cuff tear intervention, and therefore to decide whether or not the patient should be operated at all, different factors have to be considered. Structural factors, i.e. tear size, muscle atrophy, fatty degeneration, etc., and clinical factors, i.e. age, patients’ expectation, surgeons’ experience, etc. one of the most important factors is the apparent and unfortunately irreversible fatty degeneration has been semiquantitatively graded 1994 by Goutallier et al. due to CT scans. From 0 to 4, that is from no fatty deposits to more fat than muscle tissue. Since MRI became the gold standard for rotator cuff diagnosis, it is recommended to combine the Goutallier grading with oblique MR images.
The findings of Kim’s et al. study suggest that tear size and location are straightly linked to the muscular fatty degeneration. Predominantly an affected anterior part of the musculus supraspinatus tendon seems to trigger the degeneration. This is why the orthopedic surgeon should pay intense attention at fixating the anterior aspect of the supraspinatus securely and with care. On the contrary the infraspinatus muscle seems to be more reliant on the tear size than its localization. Naturally the bigger the tear, the more devastating the fatty degeneration. Of 251 examinated shoulders with a full-thickness rotator cuff tear, more than one third had fatty degeneration in either the supraspinatus or infraspinatus, or even both. Since fat is a potent sound wave reflector, fat deposits are clearly visible as intense echogenic structures. And thus detection via ultrasonography is a moderate to excellent supplement to MRI used as the soft part gold standard. The echogenicity can be graded in comparison to the overlying deltoid and trapezius muscle.
Tendinitis calcarea
Periarticular deposits in the shoulder of apatite crystals are frequent. In 7% of the population the radiologist can find deposits. But only one third has clinical discomfort. Typical age of manifestation is 70 years, women are more frequently affected.
The etiological spectrum of soft tissue calcifications at the shoulder is exceedingly broad. They range from harmless bursa calcifications as secondary findings up to tumorous changes like synovial chondromatose. The precise differentiation between calcifications at supraspinatus, infraspinatus or teres minor has finally no clinical signification. Tendon and bursa calcifications can be reabsorbed and thus disappear radiologically, in particular if they penetrate into the bursa subacromialis-subdeltoidea.
Findings by accident should be categorized as periarthropathia calcificans. Often are those changes combined with fibro-ostotic osteo-proliferations at the antero-inferior acromion and at the tuberculum majus.
In order to evaluate how acute the just detected changes are, ultrasonography can easily help by showing fluidity in the bursae or rotator cuff lesions. If the calcifications are very dense they can lead to mis-interpretations like ligament ossification or even osseous tear.
Supraspinatous fossa
The supraspinatous fossa of the posterior aspect of the scapula is smaller than the infraspinatous fossa, concave, smooth, and broader at its vertebral than at its humeral end. Its medial two-thirds give origin to the Supraspinatus....
superior of the scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
(shoulder blade) to the greater tubercle
Greater tubercle
The greater tubercle of the humerus is situated lateral to the head of the humerus and posteriolateral to the lesser tubercle.Its upper surface is rounded and marked by three flat impressions....
of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
. It is one of the four rotator cuff
Rotator cuff
In anatomy, the rotator cuff is the group of muscles and their tendons that act to stabilize the shoulder. The four muscles of the rotator cuff, along with the teres major muscle, the coracobrachialis muscle and the deltoid, make up the seven scapulohumeral muscles of the human body.-Function:The...
muscles and also abducts
Abduction (kinesiology)
Abduction, in functional anatomy, is a movement which draws a limb away from the median plane of the body. It is thus opposed to adduction.-Upper limb:* of arm at shoulder ** Supraspinatus** Deltoid* of hand at wrist...
the arm at the shoulder. The spine of the scapula separates the supraspinatus muscle from the infraspinatus muscle
Infraspinatus muscle
In human anatomy, the infraspinatus muscle is a thick triangular muscle, which occupies the chief part of the infraspinatous fossa. As one of the four muscles of the rotator cuff, the main function of the infraspinatus is to externally rotate the arm and stabilize the shoulder joint.-Origin and...
, which originates below the spine.
Origin
The supraspinatus muscle arises from the supraspinous fossa, a shallow depression in the body of the scapular above its spine. The supraspinatus muscle tendonTendon
A tendon is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fasciae as they are all made of collagen except that ligaments join one bone to another bone, and fasciae connect muscles to other...
passes laterally beneath the cover of the acromion. Research in 1996 showed that the postero-lateral origin was more lateral than classically described.
Insertion
The supraspinatus tendon is inserted into the most superior facet of the greater tubercleGreater tubercle
The greater tubercle of the humerus is situated lateral to the head of the humerus and posteriolateral to the lesser tubercle.Its upper surface is rounded and marked by three flat impressions....
of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
.
The distal attachments of the three rotator cuff muscles that insert into the greater tubercle of the humerus can be abbreviated as SIT when viewed from superior to inferior (Supraspinatus, Infraspinatus, and Teres minor).
The acronym SITS regarding the rotator cuff muscles is completed by including the Subscapularis muscle, which unlike the other rotator cuff muscles attaches to the lesser tubercle
Lesser tubercle
The lesser tubercle of the humerus, although smaller, is more prominent than the greater tubercle: it is situated in front, and is directed medially and anteriorly....
of the humerus.
Innervation
The supraspinatus muscle is supplied by the suprascapular nerveSuprascapular nerve
The suprascapular nerve arises from the upper trunk . It innervates the supraspinatus muscles and infraspinatus muscles....
(C5 and C6), which arises from the superior trunk of the brachial plexus
Brachial plexus
The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral rami of the lower four cervical and first thoracic nerve roots...
and passes laterally through the posterior triangle of the neck and through the scapular notch on the superior border of the scapula. After supplying fibers to the supraspinatus muscle, it supplies articular branches to the capsule of the shoulder joint.
This nerve can be damaged along its course in fractures of the overlying clavicle
Clavicle
In human anatomy, the clavicle or collar bone is a long bone of short length that serves as a strut between the scapula and the sternum. It is the only long bone in body that lies horizontally...
, which can reduce the person’s ability to initiate the abduction
Abduction (kinesiology)
Abduction, in functional anatomy, is a movement which draws a limb away from the median plane of the body. It is thus opposed to adduction.-Upper limb:* of arm at shoulder ** Supraspinatus** Deltoid* of hand at wrist...
.
Action
Contraction of the supraspinatus muscle leads to abduction of the arm at the shoulder joint. It is the main agonist muscle for this movement during the first 10-15 degrees of its arc. Beyond 30 degrees the deltoid muscleDeltoid muscle
In human anatomy, the deltoid muscle is the muscle forming the rounded contour of the shoulder. Anatomically, it appears to be made up of three distinct sets of fibers though electromyography suggests that it consists of at least seven groups that can be independently coordinated by the central...
becomes increasingly more effective at abducting the arm and becomes the main propagator of this action.
The supraspinatus muscle is one of the musculotendinous support structures called the rotator cuff
Rotator cuff
In anatomy, the rotator cuff is the group of muscles and their tendons that act to stabilize the shoulder. The four muscles of the rotator cuff, along with the teres major muscle, the coracobrachialis muscle and the deltoid, make up the seven scapulohumeral muscles of the human body.-Function:The...
that surround and enclose the shoulder
Shoulder
The human shoulder is made up of three bones: the clavicle , the scapula , and the humerus as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints. The major joint of the shoulder is the glenohumeral joint, which...
. It helps to resist the inferior gravitational forces placed across the shoulder joint due to the downward pull from the weight of the upper limb.
The supraspinatus also helps to stabilize the shoulder joint by keeping the head of the humerus firmly pressed medially against the glenoid fossa
Glenoid fossa
Glenoid fossa can refer to:* Glenoid cavity * Mandibular fossa...
of the scapula.
For USMLE step 1, know that the supraspinatus initiates abduction of the shoulder. Without a functioning supraspinatus, the physician must start abducting the patient's arm and eventually the patient will be able to finish abduction if the deltoid is functional, which is common because the supraspinatus is innervated by the suprascapular nerve from the superior/upper trunk of the brachial plexus. The deltoid is innervated more distally by the axillary nerve, which arises from the posterior cord of the brachial plexus.
Controversy about Action
A 1963 study, "Function of the Supraspinatus Muscle and its Relation to the Supraspinatus syndrome - An experimental in Man" by B Van Linge and J D Mulder in Leiden, Holland showed that the supraspinatus does not cause the abduction of the first 30 degrees, as widely accepted, but rather is a synergist muscle. This means that it assists the deltoid, but is not, by itself the abducting muscle. In this study, the supraspinatus was anaesthetised, and the deltoid muscle was still able to complete a full range of abduction, however was not able to sustain an isometricIsometric
The term isometric comes from the Greek for "having equal measurement".isometric may mean:* Isometric projection , a method for the visual representation of three-dimensional objects in two dimensions; a form of orthographic projection, or more specifically, an axonometric projection.* Isometry and...
contraction for more than one minute. From this study, it is suggested that the "true" action of the supraspinatus is to hold the capsule in position to allow greater functional strength and stamina of the deltoid muscle.
Conventional Radiography
Although it is via conventional radiography not possible to judge muscle or tendon tissue, a simple transaxillary or y- projection is able to reveal clearly a combined and decompensated supraspinatus and subscapularis tendon damage. A significant decrease of the coraco-humeral interval is evidencing. An interval between about 9 to 14mm is physiological. An interval under 7mm is evident for a damage that affects more than only the supraspinatus muscle. Such a constriction will probably be biomechanically relevant and thus noticeable for the patient.In addition a conventional radiography, with its good bone resolution, can give advices for potential risks, i.e. shape and declination of the acromion, open meta-meso-acromial or meso-basi-acromial apophysis gap with mobile acromion fragments, and so on; Or advices for already happened damaging events, i.e. raised stand of the humerus head with discontinuous Bandi line, cystic-erosive changes at the tuberculum majus and collum anatomicum humeri, sclerosis or entheso-pathological spurs at the acromion, and so on.
Ultrasonography
Mack et al. developed an ultrasonographic procedure with which it is possible to explore almost the complete rotator cuff within six steps. It unveils clearly the whole area from the subedge of the subscapularis tendon until the intersection between infraspinatus tendon and musculus teres minor. Two of six steps focus on the supraspinatus tendon. For the longitudinal view the applicator glides about 1cm towards dorsal, beginning at the anatomically expected supraspinatus tendon spot. Out of the acromial shadow the supraspinatus tendon abounds as a beaked soft part like structure and connects to the tuberculum majus.After positioning the applicator transversally to the supraspinatus tendon, the examinator has again to glide the applicator towards dorsal. The tendon should appear as an arched semiechogenious structure between the slightly echogenious musculus deltoideus and the strongly echogenious humerus head.
Orientation-aid for the longitudinal plane:
As an aid to orientation, it is advisable to begin the examination with the delineation of the acromion, as it is easy to palpate and its identifiable echo extinction. To adjust the longitudinal plane image the way it is known in the x-rays and the physical examination, the acromion has to be visible at the image border.
Orientation-aid for the transversal plane:
Again it is advantageous to start above the acromion and then move the transducer to the humerus. The acromion echo extinction disappears and the wheel-like figure with almost concentric projection of the deltoid muscle, supraspinatus muscle tendon and humeral head-outline turns up as soon as the transducer is directed perpendicularly and parallel to the acromion edge. Using the anterior transversal plane one can depict the intraarticular part of the long head of the biceps brachii muscle. Additionally one can use the posterior transversal plane to depict the intersection of the infraspinatus muscle tendon and the posterior edge of the fossa.
| usual longitudinal front vision | usual longitudinal back vision | usual transversal side vision | |
|---|---|---|---|
| supraspinatus tendon | acromion of the left shoulder in the left half of the image and vice versa. (In order to explore the entire tendon the examiner must move the transducer from ventral to dorsal perpendicular at the acromion axis. Either trough a maximal medial rotation or an according position of the transducer it is possible to see the supra- infraspinatus tendon intersection.) | ventral right shoulder in the right half of the image and vice versa. | |
| infraspinatus tendon | scapula spine of the right shoulder in the left half of the image and vice versa. |
Magnetic Resonance Imaging
The muscles of the rotator cuff are not aligned in the standard human anatomical planes. That is why the standard planes should be conformed to the longitudinal, respectively, transversal axis of the muscle. Through the oblique coronal and oblique sagittal plane the whole rotator cuff can be explored well. The oblique coronal plane runs parallel and the oblique sagittal perpendicularly to the longitudinal axis of the supraspinatus muscle. In a T1-weighted spin-echo-image the supraspinatus muscle appears as a robust structure with a medium signal intensity. The supraspinatus tendon attaches to the upper outside surface of the tuberculum majus humeri.As in many cases, also at the supraspinatus tendon, anatomical subclinical alterations can be found which leads to MR images with seemingly damaged and to be adjusted tendons. In asymptomatic persons of course without any traumatic event Neumann C.H. et al. has found in 89% focal, linear, or diffuse increased signal intensity of the supraspinatus tendon with or without loss of the low-signal-intensity tendon margin on proton density-weighted images. This is why the group around Dr. Neumann claims that „increased signal intensity in the supraspinatus tendon on proton density-weighted images without a corresponding increase on T2-weighted images, the presence of small amounts of fluid in the subacromial space, and the lack of preservation of the subdeltoid fat plane are common findings in asymptomatic shoulders and by themselves are poor predictors of rotator cuff disease.“
Nakagaki K. et al dissected 76 shoulders in cadavers and has found in the group with a normal cuff, compared to this with tears, that not only the short diameter but also the long diameter of the slice of the supraspinatus muscle decreased in the length with increase of the cuff defect.
Kaick O. et al takes further steps in this direction and samples a striking new path by using the fact that supraspinatus tendon tears have an impact on the overall body of the muscle, i.e. retraction, atrophy. Through computer rendered MR images the three-dimensional shape of the overall body is calculable and made non-invasively visible. They confirm that this new method could in the future be an accurate alternative to the actual invasive diagnostic gold standard, the arthroscopy.
Imaging appearance of most abnormalities
Tears:Regarding rotator cuff tears the supraspinatus muscle is by far the most affected. The rotator cuff tears involved the supraspinatus in 93% of cases, the subscapularis in 38%, and the infraspinatus in 24%. This increased frequency is based on the biomechanically stressful position between the acromion and acromio-clavicular joint above and the humeral head below.
It is known and well-established that ultrasonography reliably detects and quantifies supraspinatus tears. To examine the supraspinatus tendon optimally, it is important to position the patient correctly. Especially in the ultrasonographic investigation. So which position should be generally recommended? Ferri et al. compared the widespread Crass with the modified Crass position and has come to the conclusion that in the transversal plane both positions detected the supraspinatus tears with its correct size. On the other hand at the sagittal plane the modified Crass overestimated the tear size, and that’s why the classic Crass position should be adopted.
A to supraspinatus tears and MRI limited study of Schroeder et al. showed that the intravenous addition of contrast agent in T1-weighted imaging ameliorated significantly both the principal finding of a lesion and the differentiation between partial and full ruptures. Especially for lesions less than 1cm. Dr. Schroeders group declared following principal reasons for misinterpretation: The absence of contrast agent, motion artifacts, an expansion less than 1cm, the differentiation of pure degeneration without rupture of partial ruptures, the differentiation of partial ruptures with definite degeneration of complete ruptures and the detection of covered ruptures.
Atrophy & fatty degeneration:
Only by comparative bilateral observation of the undressed shoulders, a supraspinatus and or infraspinatus muscle atrophy attracts immediately attention. This alludes most probably to a subacromial impingement, and rarely also to a nerve paralysis.
In 1989 described Björkenheim et al. already the coherence between tendinous damage and muscular atrophy / fatty degeneration. He simulated severe complete rotator cuff tears in rabbits by removing their tendon. After losing the physiological traction stress signals the muscle begins to degenerate.
For a best possible prognosis of the anatomical and functional outcome after an operative rotator cuff tear intervention, and therefore to decide whether or not the patient should be operated at all, different factors have to be considered. Structural factors, i.e. tear size, muscle atrophy, fatty degeneration, etc., and clinical factors, i.e. age, patients’ expectation, surgeons’ experience, etc. one of the most important factors is the apparent and unfortunately irreversible fatty degeneration has been semiquantitatively graded 1994 by Goutallier et al. due to CT scans. From 0 to 4, that is from no fatty deposits to more fat than muscle tissue. Since MRI became the gold standard for rotator cuff diagnosis, it is recommended to combine the Goutallier grading with oblique MR images.
The findings of Kim’s et al. study suggest that tear size and location are straightly linked to the muscular fatty degeneration. Predominantly an affected anterior part of the musculus supraspinatus tendon seems to trigger the degeneration. This is why the orthopedic surgeon should pay intense attention at fixating the anterior aspect of the supraspinatus securely and with care. On the contrary the infraspinatus muscle seems to be more reliant on the tear size than its localization. Naturally the bigger the tear, the more devastating the fatty degeneration. Of 251 examinated shoulders with a full-thickness rotator cuff tear, more than one third had fatty degeneration in either the supraspinatus or infraspinatus, or even both. Since fat is a potent sound wave reflector, fat deposits are clearly visible as intense echogenic structures. And thus detection via ultrasonography is a moderate to excellent supplement to MRI used as the soft part gold standard. The echogenicity can be graded in comparison to the overlying deltoid and trapezius muscle.
Tendinitis calcarea
Periarticular deposits in the shoulder of apatite crystals are frequent. In 7% of the population the radiologist can find deposits. But only one third has clinical discomfort. Typical age of manifestation is 70 years, women are more frequently affected.
The etiological spectrum of soft tissue calcifications at the shoulder is exceedingly broad. They range from harmless bursa calcifications as secondary findings up to tumorous changes like synovial chondromatose. The precise differentiation between calcifications at supraspinatus, infraspinatus or teres minor has finally no clinical signification. Tendon and bursa calcifications can be reabsorbed and thus disappear radiologically, in particular if they penetrate into the bursa subacromialis-subdeltoidea.
Findings by accident should be categorized as periarthropathia calcificans. Often are those changes combined with fibro-ostotic osteo-proliferations at the antero-inferior acromion and at the tuberculum majus.
In order to evaluate how acute the just detected changes are, ultrasonography can easily help by showing fluidity in the bursae or rotator cuff lesions. If the calcifications are very dense they can lead to mis-interpretations like ligament ossification or even osseous tear.