The document discusses atraumatic shoulder instability, focusing on multidirectional instability (MDI) and its classification, causes, and management strategies. It reviews the biomechanics involved, dynamic control factors, and assessment techniques for patients experiencing instability, emphasizing the importance of understanding patient histories and individual symptoms. Furthermore, it outlines treatment approaches, including physiotherapy and surgical options such as capsular plication.

1. Atraumatic Shoulder
Instability
Mr Mike Walton BMedSci BMBS MSc FRCS(T&O) MFSEM(UK)
Consultant Shoulder Surgeon

2. Natural Selection
• The ability to throw / hunt
revolutionised our survival
Armed And Deadly: Shoulder,Weapons Key
To Hunt by Christopher Joyce Charles Darwin

3. Humans
• Clavicle Lengthens
• Scapula moves
further to dorsum
• GHJ Externally
rotates
• We can Throw

4. Not Evolved Enough!!!

5. What is “Stability”

6. What is “Stability”
• Ability of a structure to maintain its position
and function under normal physiological load
(Panjabi & White)

7. What is “Stability”
• Ability of a structure to maintain its position
and function under normal physiological load
(Panjabi & White)
STATIC FACTORS
BONES
LIGMANTS
DYNAMIC FACTORS
MUSCLES

8. Instability

9. Instability

10. Instability

11. Instability
• Dynamic
• Rotator Cuff
• Concavity
Compression
• Force Couples
• Neural Control

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

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

14. 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.
Failure of
Dynamic Control

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.
Failure of
Dynamic Control

16. MDI
• Definition “MultiDirectional Instability”
• Shoulder instability in patients who have
generalised ligamentous laxity [Web Dictionary]
• Abnormal exclusion of the humeral head
on the glenoid in ALL directions [Neer]
• Instability in TWO directions [1,2,3,4]
• Instability in THREE directions [5,6,7]

17. MDI? - Patient 1
• 22 year old hairdresser
• Rotator cuff pain, Never dislocated
• Beighton 9/9
Anterior InferiorPosterior

18. MDI? - Patient 1
• 22 year old hairdresser
• Rotator cuff pain, Never dislocated
• Beighton 9/9
Anterior InferiorPosterior

19. MDI? - Patient 2
• Swimmer, no trauma
• Posterior subluxation in flexion
• Beighton 3/9. GHJ ER 90+, IR High Thoracic

20. MDI? - Patient 2
• Swimmer, no trauma
• Posterior subluxation in flexion
• Beighton 3/9. GHJ ER 90+, IR High Thoracic

21. MDI? - Patient 3
• 25 yo Rubgy player with
anterior and posterior
labral tears
• Multiple anterior and
posterior dislocations
• Symptomatic anterior and
posterior apprehension
• Beighton 0/9

22. VOTE
1 2 3

23. VOTE
1 2 3
Atraumatic
Instability
Normal
Traumatic
MDI

24. Atraumatic Instability
•Symptomatic instability
• usually in one direction
• Absence of significant trauma
• laxity (in multiple directions) a common
finding
MDI

25. • The use of laxity testing tends to result in an overestimation of the
number of patients with this condition.
• This observation is important because the results of studies may vary if
patients with traumatic instability are considered to have
multidirectional instability on the basis of laxity testing.
• Investigators studying patients with multidirectional instability should
carefully define the inclusion criteria that they used.

26. Biomechanics
• Absence of static ligament restraint (laxity)
• Failure of cuff control
• Failure of proprioception
• Recruitment of “power muscles’ as
stabilisers
• Imbalance of force couples

27. GHJ Rotation
• Internal
• Subscapularis
• Pec major
• Lat Dorsi
• Teres Maj
• External
• Infraspinatus
• Teres Minor

28. GHJ Rotation
• Internal
• Subscapularis
• Pec major
• Lat Dorsi
• Teres Maj
• External
• Infraspinatus
• Teres Minor

29. GHJ Rotation
• Internal
• Subscapularis
• Pec major
• Lat Dorsi
• Teres Maj
• External
• Infraspinatus
• Teres Minor

30. GHJ Rotation
• Internal
• Subscapularis
• Pec major
• Lat Dorsi
• Teres Maj
• External
• Infraspinatus
• Teres Minor

31. GHJ Rotation
• Internal
• Subscapularis
• Pec major
• Lat Dorsi
• Teres Maj
• External
• Infraspinatus
• Teres Minor

32. Atraumatic Instability
Peripheral
Proprioception
Central
Control

33. Atraumatic Instability
Peripheral
Proprioception
Central
Control
Dynamic
Control

34. Atraumatic Instability
Peripheral
Proprioception
Central
Control
Psychological
Fear Avoidance
Stress
Anxiety

35. Assessment (Surgeon)
• Assessment of patient
• Understanding
• Anxiety
• Secondary gain
• Assessment of
dynamic control
• Core stability - hip
control
• Scapula dyskinesis
• Cuff control
HISTORY, HISTORY, HISTORY

36. Assessment (Surgeon)
• Frank instability
• Apprehension
• Improvement testing

37. Assessment (Surgeon)
• Frank instability
• Apprehension
• Improvement testing

38. Management

39. Management
PHYSIO

40. Management II
• Capsular Plication
• Physio led decision
• Onboard patient
• Proprioceptive deficit

41. Management II
• Capsular Plication
• Physio led decision
• Onboard patient
• Proprioceptive deficit

42. Management II
• Capsular Plication
• Physio led decision
• Onboard patient
• Proprioceptive deficit

44. • Patient demographics were 32 male patients, 18 female patients (2006-13), and a
mean age of 26 years (range 16-46 years). Directions of instability were most
often anterior and inferior.There were 14 patients with posterior instability.
• We use a No. 1 polydioxanone suture to purse string the anteroinferior capsule
to the labrum. One limb of the purse string is through capsulolabral tissue at 5
o’clock.
• There were 2 patients with recurrent instability.All patients successfully returned
to work, and 45 of 50 patients returned to the same level of sport

45. Defining Groups
• Spectrum of pathology and patients
• Well motivated
• Infrequent subluxations
• Labral tears
• Normal tone

46. Defining Groups
• Hypertonia
• Inability to know in joint
• Preferring out over in
• Secondary gain
• Failure of previous
treatment
• Spectrum of pathology and patients
• Well motivated
• Infrequent subluxations
• Labral tears
• Normal tone

48. References
1. Altchek DW,Warren RF, Skyhar MJ, Ortiz G.T-plasty modification of the Bankart procedure for multidirectional instability of the
anterior and inferior types. J Bone Joint Surg Am . 1991;73: 105-12.Abstract/FREE Full Text
2. Bak K, Spring BJ, Henderson JP. Inferior capsular shift procedure in athletes with multidirectional instability based on isolated
capsular and ligamentous redundancy.Am J Sports Med . 2000;28: 466-71.Abstract/FREE Full Text
3. Flatow EL, Miniaci A, Evans PJ, Simonian PT,Warren RF. Instability of the shoulder: complex problems and failed repairs: Part II.
Failed repairs. Instr Course Lect . 1998;47: 113-25.Medline
4. Gerber C. Observations on the classification of instability. In:Warner JJP, Iannotti JP, Gerber C, editors. Complex and revision
problems in shoulder surgery . Philadelphia: Lippincott-Raven; 1996. p 9-18.
5. Pagnani MJ,Warren RF,Altchek DW,Wickiewicz TL,Anderson AF.Arthroscopic shoulder stabilization using transglenoid sutures.
A four-year minimum followup.Am J Sports Med . 1996;24: 459-67.
6. Jobe FW,Tibone JE, Pink MM, Jobe CM, Kvitne RS.The shoulder in sports. In: Rockwood CA Jr, Matsen FA 3rd, editors.The
shoulder . 2nd ed. Philadelphia:WB Saunders; 1996. p 1214-38.
7. Neer CS 2nd. Involuntary inferior and multidirectional instability of the shoulder: etiology, recognition, and treatment. Instr
Course Lect . 1985;34: 232-8
8. Pollock RG, Owens JM, Flatow EL, Bigliani LU. Operative results of the inferior capsular shift procedure for multidirectional
instability of the shoulder. J Bone Joint Surg Am . 2000;82: 919-2