Mri Of The Rotator Cuff

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: 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