**DIAGNOSES**:

-   [Instabilities:]{.underline}

    -   TUBS (**T**raumatic - **U**nidirectional - **B**ankart lesion -
        **S**urgery)

    -   AMBRII (**A**traumatic -- **M**ultidirectional -- **B**ilateral
        -- **R**ehabilitation - **I**nferior capsular shift - (Rotator)
        **I**nterval closure)

    -   AIOS (**A**cquired -- **I**nstability -- **O**verstress --
        **S**urgery)^1^

        -   "microinstability" (microtraumatic) mainly seen in overhead
            athletes

            -   Throwers, swimmers, tennis and handball players, etc.

        -   Typically unilateral (dominant shoulder)

-   [Dislocations]{.underline}

    -   Best seen on A-P view + Transscapular view ^11^

-   [Luxatio Erecta ^5^]{.underline}

    -   Uncommon, but often misdiagnosed as anterior dislocation

    -   Classic presentation:

        -   Arm hyperabducted and "locked" above the head

        -   May include brachial plexus neuropraxia and vascular
            injuries

-   [Parsonage-Turner Syndrome ^9^ :]{.underline}

    -   Acute brachial neuritis

        -   Unknown cause

            -   But, 10-25% report having vaccination or infection in
                the weeks prior to onset

        -   20-30% are bilateral

        -   Dramatically sudden onset of pain (neuritic)

        -   Followed by profound weakness in a few days

        -   Often misdiagnosed resulting in unnecessary surgery to
            shoulder or cervical spine

        -   MRI show characteristic marked swelling of affected shoulder
            muscles

        -   Typically self-limiting

            -   No known treatment, except palliative measures

-   [Quadrilateral Space Syndrome ^9^]{.underline}

    -   Can mimic rotator cuff tear

    -   Usually caused by fibrous bands (thought to be secondary to
        scarring from prior trauma) that are in the quadrilateral space
        and cause impingement of the axillary nerve

    -   MRI shows fatty atrophy isolated to the teres minor muscle

        -   This is virtually pathognomonic of quadrilateral space
            syndrome

-   [Spinoglenoid Notch Cyst or Ganglion ^9^]{.underline}

    -   Can mimic rotator cuff abnormality

    -   Suprascapular Nerve compression

    -   Almost always associated with a posterior labral tear

    -   MRI

        -   Shows a cyst or ganglion in the spinoglenoid notch

            -   The cyst can not be seen at arthroscopic or open surgery

        -   Atrophy or neurogenic edema of infraspinatus muscle may be
            an associated finding

-   [Osteoarthritis]{.underline}

    -   Rare in the shoulder ^11^

    -   Classic triad:

        -   Decreased joint space (asymmetrical)

        -   Sclerotic bone

        -   osteophytes

    -   Plain films

        -   Axillary view

        -   True AP view

-   [Rheumatoid Arthirtis]{.underline} ^11^

    -   Radiological findings:

        -   Diffuse, symmetrical joint space narrowing

        -   Marginal or central erosions

        -   Minimal subchondral sclerosis

        -   Minimal osteophytosis

        -   Subchondral cyst

        -   Periarticular osteoporosis

        -   Symmetrical soft tissue swelling

        -   Eventual joint deformities, (+/- ) subluxation

-   [Hill-Sachs]{.underline}

    -   Compression injury to posterolateral humeral head ("Hatchet
        deformity") secondary to anteroinferior shoulder dislocation

        -   Identified with A-P view + Axillary view ^11^

        -   Depth and size of defect is thought to reflect the tightness
            of the joint capsule

            -   Defects that involve \< 1/3 of the circumference of the
                humeral head are regarded as prognostically irrelevant
                ^1^

            -   Larger lesions can lead to repeated subluxations
                ("engaging" Hill-Sachs defect) with abduction and
                external rotation ^1^

    -   Incidence at arthroscopy varies from 47 -- 100% among different
        series of patients with first-time dislocations ^1^

    -   MRA ^1^

        -   Typically seen at or slightly above the level of the
            coracoid process on Transverse images

        -   In acute or subacute cases with edema (increased signal) of
            adjacent bone marrow, the impaction injury is easily seen on
            fat-suppressed intermediate/T2-weighted or STIR
            (Short-inversion Time Inversion Recovery) images

            -   Chronic lesions, especially if small, are better seen on
                CT

            -   Large (significant) lesions are sufficiently seen of MR

-   [Impingement Syndrome]{.underline}

    -   A [subacromial osteophyte spur]{.mark} is considered
        **[specific]{.mark}** for shoulder impingement syndrome ^4^

-   [Chronic Rotator Cuff Tear]{.underline}

    -   Tear sizes ^11^ :

        -   Small = \< 1cm

        -   Moderate = 1 -- 3cm

        -   Large = 3 -- 5cm

        -   Massive = \> 5cm

    -   Plain films:

        -   Irregularity of Greater Tuberosity

        -   Narrowing of Acromio-Humeral Interval ("sub-acromial space")

            -   \<7 mm

        -   Erosion of inferior aspect of Acromion

            -   No association between acromial morphology and RTC tears
                (Pearsall AW et al, 2003) ^11^

        -   "Milwaukee Shoulder" (pebble stone appearance of articular
            cartilage of G-H joint

    -   Arthrogram:

        -   Can be 85% sensitive and specific for complete tears

    -   MRI:

        -   Supraspinatus tears are difficult to see on conventional MRI
            in young athletes ^8^

            -   Because they are often small and may not appear as large
                fluid-filled defects commonly seen in older patients

        -   [95% sensitive and specific for complete tears]{.mark}

            -   3 most accurate MRI signs for supraspinatus are ^4^ :

                -   Tendon discontinuity

                    -   Most specific sign

                        -   *Most sensitive sign is
                            subacromial-subdeltoid bursal fluid*

                -   Musculotendinous junction retraction

                -   Tendon thinning

        -   85% for partial tears/chronic tendonitis

        -   [Subscapularis tears ^3^ :]{.mark}

            -   [Seen in 45 (2%) of 2167 RCTs on MRI]{.mark}

                -   [Best seen in Sagittal oblique plane]{.mark}

                -   [27% partial tears]{.mark}

                -   [73% complete tears]{.mark}

            -   [almost all were extensions of typical RCT]{.mark}

                -   [35 (79%) from supraspinatus]{.mark}

                -   [25 (56%) from infraspinatus]{.mark}

                -   [2 (4%) from teres minor]{.mark}

            -   [Biceps tendon:]{.mark}

                -   [Bicipital dislocation seen in 22 (49%)]{.mark}

                -   [complete tears seen in 3 (7%)]{.mark}

                -   ["naked humerus" sign seen in 31 (69%)]{.mark}

[]{.mark}

-   Ultrasound

    -   Can detect "significant" (full-thickness) tears better than
        partial-thickness tears

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-   [Adhesive Capsulitis]{.underline}

    -   MRI, T2-weighted, with gadolinium enhancement is better than MRA
        ^12^

        -   25 out of 25 showed enhancement at rotator interval

        -   22 out of 25 showed enhancement at axillary recess

    -   Opacified lymphatic channels (due to increased intracapsular
        pressure)

    -   Unopacified (showing no contrast) Subscapularis Recess of
        capsule

    -   Decreased size of Axillary pouch of capsule

-   Little Leaguer's Shoulder (pitchers)

    -   Widening and irregularity of proximal humeral physis

-   [Bankart lesions]{.underline}

    -   MOST common labor-ligamentous injury in first-time traumatic
        shoulder dislocations ^1^

    -   Due to lost contact with periosteum, these show no tendency to
        heal.

        -   Surgery required

    -   MR Arthrography:

        -   Shows deformed anteroinferior labrum which is completely
            separated from the glenoid ("floating" in anterior capsular
            recess), but adherent to anterior band of IGHL

        -   Torn periosteum often seen in transverse MRA sequences

-   [Bony Bankart lesions]{.underline}

    -   MRA less accurate than CT or CT-A ^1^

        -   Small fragments easily missed on MRA

            -   Especially with use of fat-suppression

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-   Sagittal oblique MR-A are useful, however, to estimate geometry of
    the glenoid

    -   Osseous fragment avulsed

        -   Critical fragment size is \> 7mm in width

            -   Causes A-P diameter of glenoid to be small at inferior
                aspect ("inverted pear")

                -   Precludes arthroscopic repair

                    -   Re-fixation or bone grafting indicated

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-   [Perthes lesion]{.underline} (variant on Bankart lesion) ^1^

    -   Anteroinferior labro-ligamentous complex is detached from the
        glenoid, but the periosteum remains intact and is stripped
        anteromedially

        -   Integrity of periosteum allows partial healing of the labrum
            and may become re-synovialized

            -   So can look normal on arthroscopic inspection

            -   If non-displaced, also difficult to detect on MRA
                because scar tissue can block contrast media from
                entering labral tear

                -   ABER position may be more sensitive by helping to
                    separate base of labrum from glenoid

                -   But may be seen better in conventional transverse
                    image in some cases (see example)

-   [ALPSA (anterior labro-ligamentous periosteal sleeve avulsion)
    lesions]{.underline} ^1^

    -   Anteroinferior labral avulsion that leads to medial displacement
        ("medialized Bankart lesion") and inferior rotation of the
        labro-ligamentous complex together with the intact periosteum,
        in a sleeve-like fashion

        -   Causing incompetence of IGHL (anterior instability)

        -   More common in recurrent (than first-time) traumatic
            dislocations

    -   Transformation of this lesion into a Bankart lesion by
        dissection, then doing Bankart repair has been recommended as
        treatment of choice

    -   MRA

        -   Typical medial and inferior displacement best seen on
            Transverse and Coronal Oblique images

        -   Shows a nodular shape of fibrous tissue with a cleft or
            indentation between it and the glenoid

-   [GLAD (glenolabral articular disruption) lesion]{.underline} ^1^
    (described by Neviaser)

    -   Superficial tear of anteroinferior labrum in combination with an
        articular cartilage lesion of the anterior inferior quadrant of
        the glenoid

        -   NOT usually associated with anterior instability

        -   Inferior based labral flap tear without evidence of
            capsule-periosteal stripping

    -   Thought to be result of impaction while arm is abducted and
        externally rotated

    -   Most common clinical presentation is persistent anterior
        shoulder pain after FOOSH

    -   Arthroscopic debridement is treatment of choice

-   [HAGL (humeral avulsion of glenohumeral ligaments)
    lesion]{.underline} ^1^

    -   Does NOT involve labor-ligamentous complex at the glenoid

    -   Represents isolated tear of the IGHL at its humeral insertion

        -   "floating anterior IGHL"

    -   Associate with anterior instability

        -   Seen mostly in male athletes in contact sports (rugby,
            American football, ice hockey)

    -   Can be overlooked if humeral neck is not specifically searched
        at arthroscopic or open surgery

        -   Only diagnosed with confidence by use of MRA

            -   Shows "J-shaped" rather than "U-shaped" structure on
                Coronal oblique images

            -   Acute injuries usually associated with edematous changes
                of soft tissues anterior to humeral neck

            -   20 % occur with bony avulsion (Bony HAGL = BHAGL)

                -   On rare occasions associated with classic Bankart
                    lesion

-   ["Non-classifiable" labro-ligamentous injuries:]{.underline}

    -   MRA is helpful in identification of these injuries

    -   Characterized by swollen (and deformed) inferior glenohumeral
        ligament complex without distinction or differentiability of the
        labrum, IGHL, and scapular periosteum

-   [AMBRII]{.underline} ^1^ :

    -   No specific findings to diagnose atraumatic instability by MRI
        or MRA

    -   Non-athletes may show increased capsular volume but little or no
        substantial alterations of the intraarticular structures

    -   Athletes frequently have laxity associated with secondary damage
        to the labrum (may be hypoplastic or torn and may appear swollen
        due to degenerative changes), biceps anchor, and rotator cuff
        (including articular surface)

\- [AIOS (microtraumatic instability)]{.underline} ^1^ :

-   Posterosuperior (glenoid) Impingement (PSI):

    -   A form of internal impingement common in overhead athletes

        -   Present with acute or chronic shoulder pain

    -   "kissing lesion" seen in ABER position MRA

        -   Includes corresponding lesions of the undersurface of the
            rotator cuff, the Posterosuperior labrum, the greater
            tuberosity, and the superior body glenoid

    -   Associated with elongation or tears of the IGHL

-   MRA shows;

    -   Capsular laxity

        -   anterior (from abduction external rotation)

        -   posterior (from adduction, flexion, internal rotation)

    -   posterosuperior labral injuries ranging from degeneration and
        fraying to tearing and detachment

        -   SLAP lesions (high correlation)

        -   May be associated with ganglia

    -   Rotator cuff tears from secondary impingement

        -   Involves posterior part of supraspinatus tendon, unlike
            subacromial impingement

    -   Bony lesions of greater tuberosity and superior glenoid

        -   Including erosions, bone marrow edema, cyst formation, and
            sclerosis

        -   Best seen on fat-suppressed intermediate or T2-weighted
            images

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-   [Bicep Tendon rupture]{.underline}

    -   Arthrogram

        -   "Naked humerus" sign

-   [Osteonecrosis (aka Avascular necrosis)]{.underline}

    -   Increased risk with chronic steroid use

    -   Plain films

        -   Osteosclerosis

        -   Cystic changes

        -   Irregular subchondral surface

-   [SLAP (superior labrum anterior-to-posterior) lesions]{.underline}
    ^1^ :

    -   4 types described by Snyder

        -   Type 1

            -   degenerative fraying of superior labrum

        -   Type 2 (MOST common)

            -   avulsion of superior labrum and biceps anchor from
                glenoid

            -   often seen in athletes with traumatic anterior
                instability

                -   often Bankart lesions are the primary lesion with
                    the SLAP being an associated lesion

                -   tears often originate at anteroinferior
                    labro-ligamentous complex and extend cranially up
                    into the superior labrum and biceps anchor

*\[Types 1 and 2 are typically caused by repetitive torsion of the
biceps*

*anchor..." peelback mechanism" in overhead athletes\]*

-   Type 3

    -   bucket-handle tear of superior labrum with preserved bicep
        anchor

-   Type 4

    -   Bucket-handle tear of superior labrum involving the long head of
        biceps tendon

*\[ Types 3 and 4 are more common after FOOSH or falling on flexed
elbow\]*

-   Further classified as being with or without associated lesions

    -   Include involvement of MGHL, rotator cuff, and other labral
        injuries

-   Surgical repair is indicated in all SLAP lesions, except Type 1
    lesions, which are usually of no clinical relevance

    -   For Types 2 and 4, re-fixation of biceps insertion

        -   To reduce instability and secondary impingement

    -   For Type 3, surgical debridement, not reattachment, is usually
        done

-   MRA is useful in identifying, but is limited in classifying, SLAP
    lesions

    -   SLAP lesions are best seen in coronal oblique images

        -   Type 1 -- only infrequently diagnosed by MRI, but may show
            increased signal intensity and/or surface irregularity of
            superior labrum

        -   Type 2 -- characterized by linear extension of contrast
            media into superior labrum and the biceps anchor

            -   False (+) and false (-) can be caused by
                misinterpretation of a [sublabral recess]{.mark} (a
                common anatomic variant) as a tear and vice versa

                -   This recess has a \>70 % incidence in cadaveric
                    studies

                -   Seen as a variably sized synovial cleft between the
                    superior labrum and the bony glenoid pointing
                    superomedially toward the supraglenoid tubercle

                    -   Therefore seeing orientation in a lateral or
                        superior direction is MOST important criteria
                        for correctly diagnosing a SLAP

                    -   But if medial, look for irregular margins and/or
                        relatively wide separation between labrum and
                        glenoid

        -   Type 3 -- shows triangular fragment outlined by contrast
            indicating separation of the avulsed superior labrum from
            intact biceps tendon

        -   Type 4 -- similar to Type 3 but tear extends into bicep
            tendon

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-   [Tumors (neoplastic lesions)]{.underline}

    -   Borders

        -   Slow-growing lesions

            -   Defined, sharply outlined, sclerotic borders

        -   Aggressive lesions

            -   Indistinct borders

            -   Wide transitional zone

            -   Minimal reactive sclerosis

    -   Matrix types

        -   Osteoblastic (bone producing; as in Osteosarcoma)

            -   Looks "fluffy" (cotton ball-like or cloud-like)

        -   Cartilaginous

            -   Looks "popcorn-like", punctate, or strippled

            -   Chondrosarcoma is a malignant cartilage-producing tumor

                -   Commonly found at proximal humerus, pelvis, and knee

                -   Occurs in older patients

                -   Radiographs show

                    -   Thickened eroded cortex

                    -   Calcified strippled matrix

                    -   Scant periosteal reaction

                    -   Soft tissue extension

    -   Periosteal reactions

        -   Interrupted (indicates an aggressive lesion, such Ewing
            sarcoma)

            -   Sunburst or laminated ("onion skin") appearance

        -   Uninterrupted (often seen in benign lesions, such as osteoid
            osteoma...a cortical bone lesion)

            -   Demonstrated by periosteal density

    -   Soft tissue extensions (masses)

        -   Rare in benign lesions

        -   Malignant lesions often have extensions that demonstrate
            preserved soft tissue planes

        -   Osteomyelitis may have a diffuse sift tissue extension that
            obliterates tissue planes

^1^ Woertler, K. & Waldt, S. (2006). MR imaging in sports-related
glenohumeral instability. [Eur Radiol,16,]{.underline} 2622-2636.

^2^ Dinnes, J. et al. (2003). The effectiveness of diagnostic tests for
the assessment of shoulder pain due to soft tissue disorders: a
systematic review. [Health Technol Assess, 7]{.underline}(29),iii,
1-166.

^3^ Li, X. et al. (1999). MR evaluation of subscapularis tears. [Comput
Assist Tomogr, 23]{.underline}(5), 713-717.

^4^ Tan, R.K. (1998). A review of the role of magnetic resonance imaging
in the evaluation of shoulder impingement syndrome and rotator cuff
tendon tears. [Ann Acad Med Singapore, 27]{.underline} (2), 243-247.

^5^ Grate, I. Jr. (2000). Luxation erecta: a rarely seen, but often
missed shoulder dislocation. [Am J Emrg Med, 18,]{.underline} 317-321.

^6^ Koskinen, S. et al. (1997).Orthopedic and interventional
applications at lowfield MRI with horizontally open configuration. A
review. [Radiolog, 37]{.underline} (10), 819-824.

^7^ Blanco, R. et al. (2005). Interventional and intraoperative MRI at
low field scanner - a review. [Eur J Radiol, 56]{.underline} (2),
130-142.

^8^ Magee T, Williams D, and Mani N. (2004). Shoulder MR Arthography:
which patient group benefits most? [American Journal of Radiology,
183]{.underline}, 9690974.

^9^ Helms, C. (2002). The importance of MR imaging in Sports Medicine.
[Radiology, 224]{.underline}, 631-635.

^10^ Wagner, M. & Helms, C. (1999). MR imaging of the shoulder: value of
joint fluid in the characterization of rotator cuff and glenoid labral
abnormalities.[Am J Roentgenol, 172]{.underline}, 4.

^11^ Notes from *Radiology for PTs*, COL Douglas Kersey Advanced
Clinical and Operational Practice Course, October 2004.

^12^ Manton GL et al. (2001). Utility of MR arthrography in the
diagnosis of adhesive capsulitis. [Skeletal Radiology,
30]{.underline}(6), 326-330.