Current Concepts in Shoulder Instability

Mr Mike Walton BMedSci BMBS MSc FRCS(T&O) MFSEM(UK)

Consultant Shoulder Surgeon

Natural Selection

• The ability to throw / hunt revolutionised our survival

Armed And Deadly: Shoulder, Weapons Key To Hunt by Christopher Joyce Charles Darwin

Quadrapeds

• Straight Line of Pull

• Shoulder flexor & elbow extensor

• Powerful stride

Bipedal Apes

• Dorsally placed scapula

• Internal rotation of GHJ

Apes

• Dorsally placed scapula

• Internal rotation of GHJ

Humans

• Lengthened clavicle

• Scapula moves further to dorsum

• GHJ Externally rotates

Humans

• Clavicle Lengthens

• Scapula moves further to dorsum

• GHJ Externally rotates

• We can Throw

Not Evolved Enough!!!

Instability

• GlenoHumeral joint is Inherently Unstable

• The most commonly dislocated joint in body

• Usually Anterior

• Combined ER and ABduction

Instability

Instability

Instability

Instability

• Dynamic

• Concavity Compression

• Force Couples

• Neural Control

Instability

Lewis A, Kitmura T & Bayley JIL. The classification of shoulder instability: new light through old windows!Current Orthopaedics, 2004; 18(2):97-108.

Instability

Lewis A, Kitmura T & Bayley JIL. The classification of shoulder instability: new light through old windows!Current Orthopaedics, 2004; 18(2):97-108.

Traumatic Structural

Traumatic Structural

Traumatic Structural

Traumatic Structural

Traumatic Structural

Traumatic Structural

HAGL

Assessment

• Mechanism of injury

• Apprehension Tests

• Xrays

• MR Arthrogram

• Gadolinium joint injection

Modified O’Briens Test

• Forward Elevation to 90

• Adduction / Internal Rotation

• Pain - SLAP

• WEAKNESS - Post Instability

Modified O’Briens Test

• Posterior Translation occurs in simulated Active Compression Test

J Shoulder Elbow Surg. 2013 Mar;22(3):365-74. doi: 10.1016/j.jse.2012.02.003. Epub 2012 May 19. Glenohumeral contact pressure in a simulated active compression test using cadaveric shoulders. Lin T1, Javidan P, McGarry MH, Gonzalez-Lomas G, Limpisvasti O, Lee TQ.

Assessment

• Mechanism of injury

• Apprehension Tests

• Xrays

• MR Arthrogram

• Gadolinium joint injection

Investigations

• MR Arthrogram

• Accurate for isolated anterior and posterior lesions (78.5%, 69%)

• Accuracy ONLY 37% in combined lesions

Bone Loss

• Predictors of failure

• Age

• Glenoid Bone Loss

• Engaging Hill-Sachs

Ahmed I, Ashton F, Robinson CM. Arthroscopic Bankart repair and capsular shift for recurrent anterior shoulder instability: functional outcomes and identification of risk factors for recurrence. J Bone Joint Surg Am. 2012 Jul 18;94(14):1308-15

Atraumatic Instability

Lewis A, Kitmura T & Bayley JIL. The classification of shoulder instability: new light through old windows!Current Orthopaedics, 2004; 18(2):97-108.