Shoulder Instability Shoulder Instability Presented by: Dr.Abdulrahman Algarni Dr.Abdulrahman Algarni
ٍ Shoulder is the most commonly dislocated joint.In 95% the displacement is anterior and the remainder is posterior or multidirectional.
Anatomy and biomechanics Static and Dynamic Restriants. Static include glenoid labrum,articular conformity,negative pressure,capsule and capsuloligamentous structures. The Ant capsule is tight during Ext Rot & the Post during Int Rot.
These include CHL and SGHL:limit Inf Trans & Ex Rot(Add),Post Trans(Flex,Add,Int Rot). MGHL limit Inf Trans(Add,Ex Rot),Ex Rot (Add), Ant-Post Trans (45 Abd,Ex Rot).
The IGHLC is the primary restraint to Ant,Pos,and Inf Trans (45-90 Abd). The Dynamic restraints include joint concavity compression produced by synchronised contraction of Rotator Cuff.
Anterior Instability
Posterior Instability Many cases are atraumatic. Acute post dislocation is rare,history of epilpsy or severe electric shock +/- fracture of the proximal humerus or indentation.
Diagnosis In the acute stage : held in Int Rot & resist Ex Rot. AP X-Ray : light-bulb appearance of proximal humerus and Axillary veiw if abduction is possible.
Recurrent instability is almost always a posterior subluxation when the arm is held in Flex & Int Rot. + posterior drawer test + posterior apprehension test
Treatment Many cases are best treated by physiotherapy. Surgery is indicated with recurrent traumatic or persistent atrumatic instability with no gross joint laxity. Recurrence is upto 50%.
These include : -Posterior capsulorraphy. -Posterior bone block. -Posterior glenoid osteotomy with excessive glenoid retroversion.
Multidirectional Insability Usually atraumatic,bilateral, associated with ligamentous laxity and sometimes weakness of shoulder muscles. Usually atraumatic,bilateral, associated with ligamentous laxity and sometimes weakness of shoulder muscles.
Clinical Features - Difficult to diagnose with certainty, but is suggested when both anterior & posterior drawer, apprehension test and sulcus sign are positive often with joint laxity elsewhere.
Treatment - Physiotherapy -Surgical treatment : -Arthroscopic thermal capsular shrinkage -Inferior capsular shift.