MRI of the rotator cuff
Functional considerations
• The muscles of the rotator cuff resist the upwards force of the deltoid muscle by depressing the humeral head.
Functional considerations
• The muscles of the rotator cuff compress the humeral head against the glenoid cavity, increasing joint stability
Anatomic considerations
• Any process that narrows the subacromial space may affect the rotator cuff
Anatomic considerations
• Any process that narrows the subcoracoid space may affect the rotator cuff
Pathological considerations
• Exagerated tensile forces leads to failure at:– Musculotendinous junction– Tendon insertion to bone– In bone
Pathological considerations
• In presence of tendon degeneration excessive tensile forces may lead to failure within the tendon itself
Pathological considerations
• In certain positions eg. Adduction, the avascular region is made larger
Pathological considerations
• Cuff degeneration is associated with aging
• Pathology is fibrovascular proliferation and disorganisation with no inflammation
• Not a tendonitis – tendonosis or tendonopathy
Pathological considerations
• Cuff degeneration is associated with aging
• Pathology is fibrovascular proliferation and disorganisation with no inflammation
• Not a tendonitis – tendonosis or tendonopathy
Classification of tears
• Massive tear : Full thickness tear involving more than one tendon
• Articular side• Bursal side• Intrasubstance• Low grade < 50% thickness• Medium grade 50%• High grade > 50%
Classification of tears
• Retraction• Presence or absence of muscle
atrophy– From muscle disuse related to tear– Tendon retraction with nerve injury
• Irregularity of the tendon• Articular fluid• Bursal fluid
Classification of tears
• Retraction• Presence or absence of muscle
atrophy– From muscle disuse related to tear– Tendon retraction with nerve injury
• Irregularity of the tendon• Articular fluid• Bursal fluid
Classification of tears
• Direction of tear– Vertical– Oblique– Horizontal
MR arthrography
• Standard MR inconclusive• Post op cases• Special circumstances– Posterior superior impingement– Rotator interval lesions
Cuff tears : special considerations• Rim – rent tears– With aging the inner fibres of the
tendon peel away from the greater tuberosity
– Less common than critical zone tears– Young > old
Cuff tears : special considerations• Intramuscular ganglia• Rotator interval tears• Musculotendinous tears• Laminated tears• Greater tuberosity fractures– If > 5mm displacement assoc. With cuff
tear, my require ORIF
Cuff tears : special considerations• Lesser tuberosity fractures
Treatment
• Non operative– Modification of activity– Exercises to strentghen muscles
• Operative– Open or arthroscopic– Rotator cuff repair– Subacromial decompression
Treatment
• Acromioplasty– Resect and smooth undersurface of
acromion– Resect coraco-acromial ligament– When needed, remove AC joint
osteophytes, distal clavicle
Treatment
• Repair torn tendon– Advance cuff tendons– Place and tighten tendon sutures– Screws used to reinforce repair– Arthroscopic repair
Impingement
• External– Subacromial or Subcoracoid• Tendon degeneration• Abnormality coracoacromial arch
– Altered acromial shape– ACJ OA– CAL thick– Os acromiale– GHJ instability
Impingement
• Alteration acromial morphology– Degree lateral slope: <or> 10 degrees– Shape in saittal plane• 1=straight• 2=curved• 3=angular
Impingement
• Alteration coracoid morphology– Large or laterally placed – Decrease coracohumeral distance
Impingement
• Internal impingement– Posterosuperior• Impingement of undersurface of the cuff on
the posterosuperior part of glenoid
– Anterosuperior• Impingement of BT,CAL,SGHL and
anterosuperior labrum• Associated SLAP lesion and supraspinatus
tears
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