1 STABILITY Flashcards
What is Stability of the shoulder?
Stable platform
Link between humeraus and thorax
Stability of GH Joint
What are the stabilizing mechanisms of the shoulder?
- Non ligamentous
- 1 balance
- 2 concavity compression
- 3 adhesion cohesion
- Ligamentous
- 4 capsuloligamentous constraint
What is balance of the shoulder?
Net humeral joint reaction force passes through glenoid fossa
Larger Arc = Larger Stability
Scapular protraction = more stability
Scapular retraction = Less stability
How do muscules of the shoulder play a part in balance?
Maintains stability mechanisms
Can fail in cases of:
muscular imbalnces
Abnormal glenoid version
What is concavity compression?
Compression of convex humeral head to convave glenoid fossa
( stabilizes against anterior or posterior translation)
stability from:
- depth of concavity
- Magnitude of compressive force RC
What provides superior stability?
Supra spinatus Provides superior compression and stability
(DOES NOT depress head of humerus against upward pull of delts)
Cuff muscles = compressors of head into glenoid concavity
- Subscap + infrapinatus
What is adhesion Cohesion?
Joint Surfaces wet with fluid held together by molecular attraction of fluid into itself and joint (suction cup)
Stability related to:
- adhesive and cohevisve properties of joint fluid
- wetability of joint surfaces
- Area of contact b/w gleniod socket and humerus
What is the syringe effect and how does it promote stability?
Closed space within the GH joint - minimal free fluid, joint spaces not readily distracted
Mvmt restricted by NEGATIVE fluid pressure
- adds resistance to distraction by drawing capsule inwards and tightening fivers
Describe the capsuloligamentous constraint
“Check reigns”
Not primary stabilizers and connect effectivly hold humeral head centered in glenoid socket in most functional positions of joint
Post capsule limits across body ADDuction
What is the IGHL?
Condensed and thickened
Strategically placed to check ROM of joint when arm elevated and forced ER
What are some signs/tests of shoulder instability?
- Sulcus sign
- Apprehension test
- Relocation test
- Obriens Active compression test
- Anterior Slide test
- load and shift
- Crank test
What does TUBS stand for?
(torn loose)
Traumatic, Unidirectional, Bankart, Surgery
Onset with violent trauma
Recurrept episodes, functional problems in posterior plane
Usually need medial assistance to reduce
Uni directional laxity
X rays postive (bankart, hill-sachs)
What does AMBRII stand for?
Atraumatic (or microtraumatic)
Multidirectional, Bilateral, Rehab, Inferior capsular shift, Rotator Interval
Younger, insideous onset, episodes, spontaneous reduction, negative Xrays
Describe instability anteriorly and posteriorly
Anterior (AB + ER)
- 97% of dislocation
Posterior (FOOSH)
Bankart Lesion
Detachment of anterior glenoid labrum
