Rotator cuff
Encyclopedia
In anatomy
, the rotator cuff is the group of muscle
s and their tendon
s 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 (those that connect to the humerus
and scapula
and act on the glenohumeral joint) muscles of the human body
.
(shoulder joint) stability. These muscles arise from the scapula
and connect to the head of the humerus
, forming a cuff at the shoulder joint. They hold the head of the humerus in the small and shallow glenoid fossa
of the scapula. The glenohumeral joint has been analogously described as a golf ball
(head of the humerus) sitting on a golf tee (glenoid fossa).
During abduction of the arm, the rotator cuff compresses the glenohumeral joint, a term known as concavity compression, in order to allow the large deltoid muscle
to further elevate the arm. In other words, without the rotator cuff, the humeral head would ride up partially out of the glenoid fossa, lessening the efficiency of the deltoid muscle. The anterior and posterior directions of the glenoid fossa are more susceptible to shear force perturbations as the glenoid fossa is not as deep relative to the superior and inferior directions. The rotator cuff's contributions to concavity compression and stability vary according to their stiffness and the direction of the force they apply upon the joint.
The supraspinatus muscle fans out horizontally band to insert on the superior and middle facets of the greater tuberosity. The greater tubercle projects as the lateral
most structure on anterior to posterior radiographs of the shoulder with the bicipital groove just medial to it at the humeral head. Medial to this, in turn, is the lesser tuberosity of the humeral head. The subscapularis muscle origin is divided from the remainder of the rotator cuff origins as it is deep to the scapula
.
, leading to pain
and restricted movement of the arm. A torn rotator cuff
can occur following a trauma to the shoulder or it can occur through the "wear and tear" of tendons, most commonly that of the supraspinatus under the acromion. It is an injury frequently sustained by athletes whose duties involve making repetitive throws, such as cheerleaders, baseball
pitcher
s, American football
quarterback
s, volleyball
players (due to their swinging motions), water polo players, team ropers, shotput throwers (due to using poor technique), swimmers, boxers, kayakers, fast bowlers
in cricket, tennis players (due to their service motion) and tenpin bowlers due to the repetitive swinging motion of the arm with the weight of a bowling ball
. This type of injury also commonly affects orchestral conductors, choral conductors, and drummers due to the swinging motions and other movements used to lead their ensemble. It is commonly associated with motions that require repeated overhead motions or forceful pulling motions.
of relevant research found that the accuracy of the physical examination is low. The Hawkins-Kennedy test has a sensitivity of approximately 80% to 90% for detecting impingement. The infraspinatus and supraspinatus tests have a specificity of 80% to 90%.
is an initial response to injury recommended by health providers:
Cold Compression Therapy
shoulder wraps facilitate the icing and compression of an otherwise difficult body area to ice and compress.
Depending on severity of symptoms, further imaging with radiograph, or MRI may be warranted to see if surgery or an underlying bone injury exists.
Strengthening the rotator cuff allows for increased loads in a variety of exercises. When weightlifters
are unable to increase the weight they can lift on a pushing exercise (such as the bench press
or military press
) for an extended period of time, strengthening the rotator cuff can often allow them to begin making gains again. It also prevents future injuries to the glenohumeral joint, balancing the often-dominant internal rotators with stronger external rotators. Finally, exercising the rotator cuff can lead to improved posture, as without exercise to the external rotator, the internal rotators can see a shortening, leading to tightness. This often manifests itself as rounded shoulders.
Hodler et al. recommend to start scanning with conventional x-rays taken from at least two planes, since this method gives a wide first impression and even has the chance of exposing any frequent shoulder pathologies, i.e. decompensated rotator cuff tears, tendinitis calcarea, dislocations, fractures, usures and/or osteophytes. Furthermore are x-rays required for the planning of an optimal CT or MR image.
Conventional x-rays and ultrasonography are the primary tools used to confirm a diagnosis of injuries sustained to the rotator cuff. For extended clinical questions, imaging through Magnetic Resonance with or without intraarticular contrast agent is indicated.
The conventional invasive arthrography is now-a-days being replaced by the non-invasive MRI and US and is used as an imaging reserve for patients who are contraindicated for MRI, for example pacemaker-carriers with an unclear and unsure ultrasonography.
This method allows to judge:
The humerus head should be aligned in the neutral position and external rotation in a way towards the socket, that a fictive continuous line can be seen. This line is called Bandi line, otherwise known as the Ménard-Shenton line. A discontinuous line alludes to a cranial decentralization of the humerus head.
This method allows to judge:
This method allows to judge:
This Y-projection can be traced back to Wijnblath’s 1933 published cavitas-en-face projection.
It must be pointed out that this projection has a low tolerance for errors and correspondingly needs proper execution.
Although musculo-skeletal US training, like medical training in general, is a lifelong process, Kissin et al. suggest that, rheumatologists who taught themselves how to manipulate US, can use US just as good as international musculo-skeletal US experts to diagnose common rheumatic conditions.
After the introduction of the high-frequency transducers in the mid-eighties, US has become a widely conventional tool for taking accurate and precise images of the shoulder to support the diagnosis.
Adequate for the examination are high-resolution, high-frequency transducers with a transmission frequency of 5, 7.5 and 10 MHz. To improve the focus on structures close to the skin an additional „water start-up length“ is advisable. During the examination the patient is asked to be seated, the affected arm is then adducted and the elbow is bent to 90 degrees. Slow and cautious passive lateral and/or medial rotations have the effect of being able to visualize different sections of the shoulder. In order to also demonstrate those parts which are hidden under the acromion in the neutral position, a maximum medial rotation with hyperextension behind the back is required.
To avoid the different tendon echogenicities caused by different instrument settings, Middleton compared the tendon’s echogenicity with that of the deltoid muscle, which is still lege artis.
Usually the echogenicity compared to the deltoid muscle is homogeneous intensified without dorsal echo extinction. Variability with reduced or intensified echo has also been found in healthy tendons. Bilateral comparison is very helpful when distinguishing and setting boundaries between physiological variants and a possible pathological finding. Degenerative changes at the rotator cuff often are found on both sides of the body. Consequently unilateral differences rather point to a pathological source and bilateral changes rather to a physiological variation.
In addition, a dynamic examination can help to differentiate between an ultrasound artifact and a real pathology.
To accurately evaluate the echogenicity of a US, one has to take into account the physical laws of reflection, absorption and dispersion. It is at all times important to acknowledge that the structures in the joint of the shoulder are not aligned in the transversal, coronal or sagittal plane, and that therefore during imaging of the shoulder the transducer head has to be hold perpendicularly or parallel to the structures of interest. Otherwise the appearing echogenicity may not be evaluated.
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 it has an 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.
The MR Imaging should provide joint details to the treating orthopedist, to help him diagnose and decide the next appropriate therapeutic step.
To examine the shoulder, the patient is lying and the concerned arm is in lateral rotation. For signal detection it is recommended to use a surface-coil. To find pathologies of the rotator cuff in the basic diagnostic investigation, T2-weighted sequences with fat-suppression or STIR sequences have proven value. In general, the examination should occur in the following three main planes: axial, oblique coronal and sagittal.
Most morphological changes and injuries are sustained to the supraspinatus tendon. Traumatic rotator cuff changes are often located antero-superior, meanwhile degenerative changes more likely are supero-posterior.
Tendons are predominantly composed of dense collagen fiber bundles. Because of their extreme short T2-relaxation time they appear typically signal-weak, respectively, dark. Degenerative changes, inflammations and also partial and complete tears cause loss of the original tendon structure. Fatty deposits, mucous degeneration and hemorrhages lead to an increased intratendinal T1-image. Edema formations, inflammatory changes and ruptures increase the signals in a T2-weighted image.
In 1999, Weishaupt D. et al. reached through two readers a significant better visibility of pully lesions at the rotator interval and the expected location of the reflection pulley of the long biceps and subscapularis tendon on parasagittal (reader1/reader2 sensitivity: 86%/100%; specificity: 90%/70%) and axial (reader1/reader2 sensitivity: 86%/93%; specificity: 90%/80%) MRA images.
When examining the rotator cuff, the MRA has a couple of advantages compared to the native MRI. Through a fat suppressed T2-weighted spin echo, MRA can reproduce an extreme high fat-water-contrast, which helps to detect water-deposits with better damage diagnosis in structurally changed collagen fiber bundles.
Human anatomy
Human anatomy is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross anatomy is the study of anatomical structures that can be seen by the naked eye...
, the rotator cuff is the group of muscle
Muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s and their tendon
Tendon
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...
s that act to stabilize 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...
. The four muscles of the rotator cuff, along with the teres major muscle
Teres major muscle
The teres major muscle is a muscle of the upper limb and one of six scapulohumeral muscles. It is a thick but somewhat flattened muscle, innervated by the lower subscapular nerve .-Origin and insertion:...
, the coracobrachialis muscle
Coracobrachialis muscle
The Coracobrachialis is the smallest of the three muscles that attach to the coracoid process of the scapula. It is situated at the upper and medial part of the arm....
and the deltoid
Deltoid 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...
, make up the seven scapulohumeral (those that connect to the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
and scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
and act on the glenohumeral joint) muscles of the human body
Human body
The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life...
.
Function
The rotator cuff muscles are important in shoulder movements and in maintaining glenohumeral jointGlenohumeral joint
The glenohumeral joint, or shoulder joint, is a multiaxial synovial ball and socket joint and involves articulation between the glenoid fossa of the scapula and the head of the humerus...
(shoulder joint) stability. These muscles arise from the scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
and connect to the head of the humerus
Humerus
The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow....
, forming a cuff at the shoulder joint. They hold the head of the humerus in the small and shallow glenoid fossa
Glenoid fossa
Glenoid fossa can refer to:* Glenoid cavity * Mandibular fossa...
of the scapula. The glenohumeral joint has been analogously described as a golf ball
Golf ball
A golf ball is a ball designed to be used in the game of golf.Under the Rules of Golf, a golf ball weighs no more than 1.620 oz , has a diameter not less than 1.680 in , and performs within specified velocity, distance, and symmetry limits...
(head of the humerus) sitting on a golf tee (glenoid fossa).
During abduction of the arm, the rotator cuff compresses the glenohumeral joint, a term known as concavity compression, in order to allow the large deltoid muscle
Deltoid 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...
to further elevate the arm. In other words, without the rotator cuff, the humeral head would ride up partially out of the glenoid fossa, lessening the efficiency of the deltoid muscle. The anterior and posterior directions of the glenoid fossa are more susceptible to shear force perturbations as the glenoid fossa is not as deep relative to the superior and inferior directions. The rotator cuff's contributions to concavity compression and stability vary according to their stiffness and the direction of the force they apply upon the joint.
Muscles composing rotator cuff
| Muscle | Origin on scapula | Attachment on humerus | Function | Innervation >- | Supraspinatus muscle Supraspinatus muscle The supraspinatus is a relatively small muscle of the upper arm that runs from the supraspinatous fossa superior of the scapula to the greater tubercle of the humerus. It is one of the four rotator cuff muscles and also abducts the arm at the shoulder... |
supraspinous fossa | superior and middle facet of the greater tuberosity 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.... |
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 Arm In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods... |
>- | infraspinous fossa | posterior facet of the greater tuberosity 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.... |
externally rotates External rotation External rotation is rotation away from the center of the body.The muscles of external rotation include:* of arm/humerus at shoulder** Deltoid muscle** Infraspinatus** Teres minor* of thigh/femur at hip ** Gluteus maximus... the arm |
>- | middle half of lateral border | inferior facet of the greater tuberosity 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.... |
externally rotates the arm | >- | subscapular fossa Subscapular fossa The costal or ventral surface of the scapula presents a broad concavity, the subscapular fossa.It provides an attachment for the subscapularis muscle.-External links: - "Scapular Region: Scapula "... |
lesser tuberosity 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.... (60%) or humeral neck Humerus The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow.... (40%) |
internally rotates Internal rotation In anatomy, internal rotation is rotation towards the center of the body.The muscles of internal rotation include:* of arm/humerus at shoulder** Deltoid muscle** Subscapularis** Teres major** Latissimus dorsi... the humerus Humerus The humerus is a long bone in the arm or forelimb that runs from the shoulder to the elbow.... |
Upper and Lower subscapular nerve (C5-C6) |
The supraspinatus muscle fans out horizontally band to insert on the superior and middle facets of the greater tuberosity. The greater tubercle projects as the lateral
Lateral
Lateral may refer to:*Lateral , an anatomical direction*Lateral canal, a canal built beside another stream*Lateral consonant, an ℓ-like consonant in which air flows along the sides of the tongue...
most structure on anterior to posterior radiographs of the shoulder with the bicipital groove just medial to it at the humeral head. Medial to this, in turn, is the lesser tuberosity of the humeral head. The subscapularis muscle origin is divided from the remainder of the rotator cuff origins as it is deep to the scapula
Scapula
In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
.
Rotator cuff tear
The tendons at the ends of the rotator cuff muscles can become tornRotator cuff tear
Rotator cuff tears are tears of one or more of the four tendons of the rotator cuff muscles. A rotator cuff injury can include any type of irritation or damage to the rotator cuff muscles or tendons....
, leading to pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
and restricted movement of the arm. A torn rotator cuff
Rotator cuff tear
Rotator cuff tears are tears of one or more of the four tendons of the rotator cuff muscles. A rotator cuff injury can include any type of irritation or damage to the rotator cuff muscles or tendons....
can occur following a trauma to the shoulder or it can occur through the "wear and tear" of tendons, most commonly that of the supraspinatus under the acromion. It is an injury frequently sustained by athletes whose duties involve making repetitive throws, such as cheerleaders, baseball
Baseball
Baseball is a bat-and-ball sport played between two teams of nine players each. The aim is to score runs by hitting a thrown ball with a bat and touching a series of four bases arranged at the corners of a ninety-foot diamond...
pitcher
Pitcher
In baseball, the pitcher is the player who throwsthe baseball from the pitcher's mound toward the catcher to begin each play, with the goal of retiring a batter, who attempts to either make contact with the pitched ball or draw a walk. In the numbering system used to record defensive plays, the...
s, American football
American football
American football is a sport played between two teams of eleven with the objective of scoring points by advancing the ball into the opposing team's end zone. Known in the United States simply as football, it may also be referred to informally as gridiron football. The ball can be advanced by...
quarterback
Quarterback
Quarterback is a position in American and Canadian football. Quarterbacks are members of the offensive team and line up directly behind the offensive line...
s, volleyball
Volleyball
Volleyball is a team sport in which two teams of six players are separated by a net. Each team tries to score points by grounding a ball on the other team's court under organized rules.The complete rules are extensive...
players (due to their swinging motions), water polo players, team ropers, shotput throwers (due to using poor technique), swimmers, boxers, kayakers, fast bowlers
Fast bowling
Fast bowling, sometimes known as pace bowling, is one of the two main approaches to bowling in the sport of cricket. The other is spin bowling...
in cricket, tennis players (due to their service motion) and tenpin bowlers due to the repetitive swinging motion of the arm with the weight of a bowling ball
Bowling ball
A bowling ball is a spherical ball made from plastic, reactive resin, urethane or a combination of these materials which is used in the sport of bowling. Ten-pin bowling balls generally have a set of three holes drilled in them, one each for the ring and middle finger, and one for the thumb;...
. This type of injury also commonly affects orchestral conductors, choral conductors, and drummers due to the swinging motions and other movements used to lead their ensemble. It is commonly associated with motions that require repeated overhead motions or forceful pulling motions.
Rotator cuff impingement
A systematic reviewSystematic review
A systematic review is a literature review focused on a research question that tries to identify, appraise, select and synthesize all high quality research evidence relevant to that question. Systematic reviews of high-quality randomized controlled trials are crucial to evidence-based medicine...
of relevant research found that the accuracy of the physical examination is low. The Hawkins-Kennedy test has a sensitivity of approximately 80% to 90% for detecting impingement. The infraspinatus and supraspinatus tests have a specificity of 80% to 90%.
Reduce pain and swelling
As with all muscle injuries, R.I.C.E.RICE (medicine)
RICE is a treatment method for soft tissue injury which is an acronym for Rest, Ice, Compression and Elevation. When used appropriately, recovery duration is usually shortened and discomfort minimized....
is an initial response to injury recommended by health providers:
- Rest means ceasing movement of the affected area.
- Icing uses ice to reduce inflammation.
- Compression limits the swelling.
- Elevation involves placing the area higher to reduce inflammation and swelling.
Cold Compression Therapy
Cold compression therapy
Cold Compression Therapy combines two of the principles of R.I.C.E. to reduce pain and swelling from a sports or activity injury to soft tissues and recommended by orthopedic surgeons following surgery...
shoulder wraps facilitate the icing and compression of an otherwise difficult body area to ice and compress.
Depending on severity of symptoms, further imaging with radiograph, or MRI may be warranted to see if surgery or an underlying bone injury exists.
Posture and sleeping positions
Postures and sleeping positions may be modified to provide relief.Strengthening
The rotator cuff can be strengthened to rehabilitate shoulder injuries, and prevent future ones. There are different exercises to target the individual rotator cuff muscles.| Description | Beginning | End >- | The most effective is the side-lying external rotation, which activates the supraspinatus, subscapularis, infraspinatus and teres minor. Lie on a bench sideways, with the arm next to the side and flexed about 90 degrees at the elbow. Rotate the upper arm, raising the dumbbell towards the ceiling to a 45 degree angle. Keep the elbow flexed, and the upper arm close to the body. Pace at two seconds up and four seconds down. This is an excellent all-around shoulder exercise. |
 |
 |
 |
 |
Strengthening the rotator cuff allows for increased loads in a variety of exercises. When weightlifters
Powerlifting
Powerlifting is a strength sport. It resembles the sport of Olympic weightlifting, as both disciplines involve lifting weights in three attempts. Powerlifting evolved from a sport known as 'odd lifts' which followed the same three attempt format but used a wide variety of events akin to Strongman...
are unable to increase the weight they can lift on a pushing exercise (such as the bench press
Bench press
The bench press is an exercise of the upper body. For bodybuilding purposes, it is used to stimulate the pectorals, deltoids, and triceps. While on his or her back, the person performing the bench press lowers a weight to the level of the chest, then pushes it back up until the arm is straight...
or military press
Military press
The military press is a variation of the overhead press weight training exercise using very strict form.The military press targets the deltoid muscles in the shoulders as well as the triceps...
) for an extended period of time, strengthening the rotator cuff can often allow them to begin making gains again. It also prevents future injuries to the glenohumeral joint, balancing the often-dominant internal rotators with stronger external rotators. Finally, exercising the rotator cuff can lead to improved posture, as without exercise to the external rotator, the internal rotators can see a shortening, leading to tightness. This often manifests itself as rounded shoulders.
Surgery
Even for full thickness rotator cuff tears, conservative care (i.e., non-surgical treatment) outcomes are usually reasonably good. However, many patients still suffer disability and pain despite non-surgical therapies. For massive tears of the rotator cuff, surgery has shown durable outcomes on 10 year follow-up. However, the same study demonstrated ongoing and progressive fatty atrophy and re-tears of the rotator cuff. Shen has shown that MRI evidence of fatty atrophy in the rotator cuff prior to surgery is predicative of a poor surgical outcome. If the rotator cuff is completely torn, surgery is usually required to reattach the tendon to the bone.Shoulder imaging
There are several ways to depict the structures of the shoulder, which consist of muscles, tendons, bones, cartilage and soft tissue. When deciding which medical imaging technique should be used, there are a couple of factors that need to be taken into account. Firstly, one has to consider the suspected clinical diagnosis. Together with the knowledge of the advantages and limitations of the various medical imaging techniques ( i.e. conventional radiography, ultrasound, computer tomography and magnetic resonance), one has to make an informed decision which technique would best suit the specific situation.Hodler et al. recommend to start scanning with conventional x-rays taken from at least two planes, since this method gives a wide first impression and even has the chance of exposing any frequent shoulder pathologies, i.e. decompensated rotator cuff tears, tendinitis calcarea, dislocations, fractures, usures and/or osteophytes. Furthermore are x-rays required for the planning of an optimal CT or MR image.
Conventional x-rays and ultrasonography are the primary tools used to confirm a diagnosis of injuries sustained to the rotator cuff. For extended clinical questions, imaging through Magnetic Resonance with or without intraarticular contrast agent is indicated.
The conventional invasive arthrography is now-a-days being replaced by the non-invasive MRI and US and is used as an imaging reserve for patients who are contraindicated for MRI, for example pacemaker-carriers with an unclear and unsure ultrasonography.
a.-p.-projection 40° posterior oblique after Grashey
The scapula should be positioned perpendicularly to the x-ray film. The body has to be rotated about 30 to 45 degrees towards the to be imaged shoulder, and the standing or sitting patient lets the arm hang.This method allows to judge:
- The joint gap and the vertical alignment towards the socket.
The humerus head should be aligned in the neutral position and external rotation in a way towards the socket, that a fictive continuous line can be seen. This line is called Bandi line, otherwise known as the Ménard-Shenton line. A discontinuous line alludes to a cranial decentralization of the humerus head.
Transaxillary projection
The arm should be abduced 80 to 100 degrees at a precise defined scapular or frontal plane.This method allows to judge:
- The horizontal alignment of the humerus head in respect to the socket, and the lateral clavicle in respect to the acromion.
- Lesions of the anterior and posterior socket border or of the tuberculum minus.
- The eventual non-closure of the acromial apophysis.
- The coraco-humeral interval
Y-projection
The lateral contour of the shoulder should be positioned in front of the film in a way that the longitudinal axis of the scapula continues parallel to the path of the rays.This method allows to judge:
- The horizontal centralization of the humerus head and socket.
- The osseous margins of the coraco-acromial arch and hence the supraspinatus outlet canal.
- The shape of the acromion
This Y-projection can be traced back to Wijnblath’s 1933 published cavitas-en-face projection.
It must be pointed out that this projection has a low tolerance for errors and correspondingly needs proper execution.
Ultrasound
There are several solid advantages of ultrasound. It is relatively advantageously priced, does not emit any radiation, it is accessible, it is capable to visualize in real time any tissue function and it allows to perform provocative maneuvers in order to replicate the patient’s pain. Those apparent benefits surely helped ultrasound to be today’s first choice for assessing tendons and soft tissues on the quick. Limitations include for example: The high degree of operator dependence, the inability to define pathologies in bones. One also has to have an extensive anatomical knowledge of the examined region and keep an open mind to normal variations and artifacts created during the scan.Although musculo-skeletal US training, like medical training in general, is a lifelong process, Kissin et al. suggest that, rheumatologists who taught themselves how to manipulate US, can use US just as good as international musculo-skeletal US experts to diagnose common rheumatic conditions.
After the introduction of the high-frequency transducers in the mid-eighties, US has become a widely conventional tool for taking accurate and precise images of the shoulder to support the diagnosis.
Adequate for the examination are high-resolution, high-frequency transducers with a transmission frequency of 5, 7.5 and 10 MHz. To improve the focus on structures close to the skin an additional „water start-up length“ is advisable. During the examination the patient is asked to be seated, the affected arm is then adducted and the elbow is bent to 90 degrees. Slow and cautious passive lateral and/or medial rotations have the effect of being able to visualize different sections of the shoulder. In order to also demonstrate those parts which are hidden under the acromion in the neutral position, a maximum medial rotation with hyperextension behind the back is required.
To avoid the different tendon echogenicities caused by different instrument settings, Middleton compared the tendon’s echogenicity with that of the deltoid muscle, which is still lege artis.
Usually the echogenicity compared to the deltoid muscle is homogeneous intensified without dorsal echo extinction. Variability with reduced or intensified echo has also been found in healthy tendons. Bilateral comparison is very helpful when distinguishing and setting boundaries between physiological variants and a possible pathological finding. Degenerative changes at the rotator cuff often are found on both sides of the body. Consequently unilateral differences rather point to a pathological source and bilateral changes rather to a physiological variation.
In addition, a dynamic examination can help to differentiate between an ultrasound artifact and a real pathology.
To accurately evaluate the echogenicity of a US, one has to take into account the physical laws of reflection, absorption and dispersion. It is at all times important to acknowledge that the structures in the joint of the shoulder are not aligned in the transversal, coronal or sagittal plane, and that therefore during imaging of the shoulder the transducer head has to be hold perpendicularly or parallel to the structures of interest. Otherwise the appearing echogenicity may not be evaluated.
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 it has an 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. |
MRI
Orthopedics established early the MRI as the tool of choice for joint- and soft tissue-imaging, because its non-invasiveness, the lack of radiation exposure, multi planar slicing possibilities and the high soft tissue contrast.The MR Imaging should provide joint details to the treating orthopedist, to help him diagnose and decide the next appropriate therapeutic step.
To examine the shoulder, the patient is lying and the concerned arm is in lateral rotation. For signal detection it is recommended to use a surface-coil. To find pathologies of the rotator cuff in the basic diagnostic investigation, T2-weighted sequences with fat-suppression or STIR sequences have proven value. In general, the examination should occur in the following three main planes: axial, oblique coronal and sagittal.
Most morphological changes and injuries are sustained to the supraspinatus tendon. Traumatic rotator cuff changes are often located antero-superior, meanwhile degenerative changes more likely are supero-posterior.
Tendons are predominantly composed of dense collagen fiber bundles. Because of their extreme short T2-relaxation time they appear typically signal-weak, respectively, dark. Degenerative changes, inflammations and also partial and complete tears cause loss of the original tendon structure. Fatty deposits, mucous degeneration and hemorrhages lead to an increased intratendinal T1-image. Edema formations, inflammatory changes and ruptures increase the signals in a T2-weighted image.
Magic angle artifact
Erickson et al. noticed and described a typical artifact and gave the phenomenon the name „magic angle“. The „magic angle“ describes a changed T2-relaxation time depending on the spatial orientation of the tissue to the main magnetic field. If parts of the tendon are located at the area of the magic angle at 55 degrees to the main magnetic field, their T2-relaxation time gets influenced and the signal heavily intensified. Unluckily these artifacts occupy similar areas where clinical relevant pathologies are found. To avoid a wrong diagnosis it is recommended to exclude this phenomenon in a case of doubt through a heavy T2-weighted sequence or an additional fat-suppression at a proton weighted sequence.MRA
While using MRI, true lesions at the rotator interval region between the parts of the supraspinatus and subscapularis are all but impossible to distinguish from normal synovium and capsule.In 1999, Weishaupt D. et al. reached through two readers a significant better visibility of pully lesions at the rotator interval and the expected location of the reflection pulley of the long biceps and subscapularis tendon on parasagittal (reader1/reader2 sensitivity: 86%/100%; specificity: 90%/70%) and axial (reader1/reader2 sensitivity: 86%/93%; specificity: 90%/80%) MRA images.
When examining the rotator cuff, the MRA has a couple of advantages compared to the native MRI. Through a fat suppressed T2-weighted spin echo, MRA can reproduce an extreme high fat-water-contrast, which helps to detect water-deposits with better damage diagnosis in structurally changed collagen fiber bundles.