instability

General

stability
Labrum-capsule-ligament

Labrum

·      important

·      deepens glenoid

·      increases contact to 3/4

·      provides site of attachment of capsule and GH ligaments

Capsule

·      thin and lax

·      offers little resistance or stability

Glenohumeral ligaments

·      reinforce anterior capsule

·      static stabilisers

Inferior glenohumeral ligament

·      prime stabiliser

·      resists anterior subluxation

·      limits external rotation at abduction > 90o

Middle glenohumeral ligament

·      acts as secondary restraint to anterior translation

·      limits external rotation at 45o abduction

Superior glenohumeral ligament

·      functions only in adduction

·      prevents downward subluxation of dependent humerus

·      no function in preventing anterior translation

Muscle

Deltoid

·      produces vertical shear

·      displaces humeral head superiorly

Rotator cuff

·      produces compressive or stabilising forces

·      subscapularis is principal dynamic anterior stabiliser in lower ranges of abduction

·      long head of biceps

Scapular movers

·      consist of

·      serratus anterior

·      trapezius

·      move glenoid into most stable position wrt. humeral head with movement

Bone

·      architecture does not contribute much

·      like golf ball sitting on tee

·      glenoid flat

·      covers 1/4-1/3 of humeral head

pathogenesis
Capsule-labrum-ligament

·      main cause

Bankart lesion

·      avulsion of capsule and labrum from rim of glenoid

·      now thought to be avulsion of inferior glenohumeral ligament complex at insertion to glenoid labrum

·      may be associated with avulsion fracture of glenoid rim

·      present in 85% of anterior dislocations

Capsular laxity

·      may be present

·      alone

·      with Bankart lesion

·      present in 30% of anterior dislocations

Muscle

·      much less frequent cause

·      rotator cuff may be attenuated or torn

·      esp. subscapularis

·      may be increased rotator interval

·      between supraspinatus and subscapularis

Bone

Glenoid rim fracture

·      usually part of Bankart lesion

·      erosion can occur with recurrent dislocations

Hill-Sachs lesion

·      osteochondral compression defect of posterior humeral head

·      produced by impaction of humeral head against glenoid rim at time of anterior dislocation

·      reverse lesion seen anteriorly with posterior dislocation

·      result of initial dislocation

·      may produce subsequent dislocations as defect lies within glenoid cavity when shoulder abducted and externally rotated

Abnormal version

·      of glenoid or humerus

·      only contributes in extreme cases

Classification

1.   direction

·      anterior (98%)

·      posterior (1%)

·      multidirectional (1%)

2.   onset

·      traumatic

·      atraumatic

·      overuse

3.   frequency

·      acute

·      recurrent

·      fixed

4.   volition

·      voluntary

·      involuntary

5.   degree

·      dislocation

·      subluxation

Acute traumatic anterior dislocation

epidemiology

·      by far the most common form of shoulder instability

·      most common in young males

·      M:F = 2:1

aetiology

·      usually indirect force on shoulder from direct force on arm

·      results in excessive abduction, extension and external rotation

·      causes disruption of anterior stabilisers

clinical
History

·      history of injury

·      severe pain in shoulder

·      may be transient parasthesiae

Examination

·      very painful, tender shoulder

·      significant muscle spasm

·      arm held across abdomen

·      hollow under acromion

·      fullness in anterior shoulder

·      may be axillary nerve palsy

Radiology
Plain x-ray

·      require

·      true AP

·      true axillary

·      if true axillary impossible, may use

·      transverse scapular

·      Garth

·      look for

·      direction of dislocation

·      associated fractures

Classification

·      according to direction seen on x-rays

·      may be

·      subacromial (most common)

·      subglenoid

·      subclavicular

·      intrathoracic

treatment
Reduction

·      as soon as possible

·      appropriate analgesia and muscle relaxation

·      atraumatic closed reduction performed

·      if unsuccessful, may require general anaesthetic

·      rarely need open reduction

·      post-reduction x-ray to

·      confirm reduction

·      rule out associated fractures

Stimpson

·      patient prone

·      arm hanging over side of bed

·      weight applied to wrist

·      scapula may be manipulated to facilitate reduction

Harvard

·      patient supine

·      traction with abduction

·      countertraction or pressure in axilla

Immobilisation

·      studies show

·      period of immobilisation does not affect subsequent redislocation rate

·      restriction from sport for 6 weeks reduces dislocation rate

·      protocol

·      sling for comfort

·      avoid provocative position (abd, flex, ER) for 6 weeks

·      avoid contact sport until full painless ROM

Rehabilitation

·      early intervention important

·      start with ROM exercises

·      pendulum

·      active assisted

·      active

·      then shoulder strengthening

·      esp. internal rotation

prognosis
Age at first dislocation

·      redislocation more common if young

·      rate of dislocation

·      < 20 - 75% (55-95)

·      20-30 - 60% (40-80)

·      30-40 - 33% (10-50)

·      > 40 - 10% (0-20)

Trauma of first dislocation

·      decreased incidence of redislocation with

·      severe trauma

·      associated fracture (usually lesser tuberosity)

Activity

·      redislocation more common in athletes

·      80% in athletes

·      30% in non-athletes

Rehabilitation

·      activity restriction and effective muscle strengthening reduces redislocation

·      overall redislocation rate 25% at 3 yrs (Army)

·      requires strict adherence with programme

Recurrent traumatic involuntary anterior instability

epidemiology

·      as above

aetiology

·      initial acute traumatic anterior dislocation

clinical
Presentation

·      may be one or combination of following

Recurrent dislocations

·      normally functioning shoulder

·      dislocation occurs with inciting event

·      dislocation usually requires reduction by someone else

·      usually quite painful

·      frequency varies

·      gradually occurs with less and less trauma

Recurrent subluxations

·      may present in two ways

1.   dead arm syndrome

·      sudden sharp paralysing pain

·      feeling of heaviness, numbness or weakness

·      associated with shoulder in Abd, Ext, ER

·      may feel as if shoulder slipping out of place

2.   shoulder pain

·      pain with overhead activities, eg. throwing

·      probably pain from impingement 2o to subluxation

Apprehension shoulder

·      fear that shoulder will ‘go out’ if arm goes into Abd and ER

·      avoid this position and activities that require it

History

·      ask

1.   trauma

·      specific injury

·      repetitive overuse

2.   volition

·      can willfully reproduce

·      do certain activities or positions reproduce

3.   arm position

·      that reproduces symptoms

4.   joints

·      contralateral shoulder problems

·      other joint problems

·      family history of similar problem

Examination

Range of movement

·      decreased active abduction may suggest

·      impingement

·      rotator cuff tear

·      decreased external rotation may be result of disuse

Stability

·      anterior instability suggested by positive anterior drawer

·      inferior instability suggested by sulcus sign

·      posterior instability suggested by positive posterior drawer

Sulcus sign

·      patient seated

·      traction applied to arm inferiorly

·      with significant inferior translation, sulcus appears

·      dimple or sulcus beneath lateral acromion

AP drawer

·      patient seated with examiner behind

·      scapula fixed with one hand

·      humeral head grasped and translated anteriorly and posteriorly

Apprehension

·      anterior instability suggested by positive anterior apprehension

·      posterior instability suggested by positive posterior apprehension

Anterior apprehension sign

·      patient seated with examiner behind

·      arm in abduction and external rotation with elbow flexed

·      examiner progressively abducts and externally rotates shoulder

·      other hand anterior to prevent dislocation

·      apprehension expressed by

·      muscle contraction to resist movement

·      look of apprehension on patient’s face

·      patient stating that manoevre reproduces functional instability and feels shoulder will come out

Jobe relocation test

·      patient lying supine

·      apprehension test repeated with posteriorly directed force on proximal humerus to relocate humeral head

·      may eliminate apprehension and pain

·      increase amount of abduction and external rotation

·      posteriorly directed force suddenly removed

·      sudden pain positive

Posterior apprehension sign

·      patient seated with examiner in front

·      am in forward flexion, adduction and internal rotation (across chest)

·      examiner applies posteriorly directed force

·      other hand stabilises scapula posteriorly

·      apprehension expressed by

·      subluxation or dislocation

·      uncomfortable sensation that mimics instability

Volition

·      ask patient if able to reproduce dislocation

treatment

·      depends on disability

·      disability dependent on

·      frequency of dislocations

·      ease or difficulty of reduction

·      presence of interval symptoms (subluxation or apprehension)

·      age of patient

·      activity requirement of patient

Nonoperative

Indications

·      minimal to mild disability

·      pain secondary to impingement

Technique

Shoulder strengthening exercises

·      set ot rubber Therabands and pulley

·      4 bands of increasing resistance

·      5 exercises

·      external rotation

·      abduction

·      extension

·      internal rotation

·      flexion

·      initially use Therabands progressively

·      then use pulley with increasing weight

·      combine with scapular exercises

·      wall and regular pushups

·      shoulder shrugs

Avoidance of provocative position

Operative

Indications

·      moderate to severe disability

Complications

·      loss of external rotation

·      redislocation

·      nerve injury

·      musculocutaneous (most common)

·      axillary

·      late osteoarthritis of glenohumeral joint

Techniques

·      may be divided into

·      bony

·      musculo-tendinous

·      capsulo-labral

Putti-Platt

·      involves shortening and overlapping of subscapularis and anterior capsule (double-breasting)

·      effectively limits anterior instability (recurrence 3%)

·      results in

·      deficit in ER (20o with arm by side and 30o with arm abducted)

·      glenohumeral osteoarthritis if overtightened

·      only 50% of athletes return to preinjury level

Magnusson-Stack

·      anterior capsule and subscapularis tightened by advancing them laterally on humerus

·      similar results to Putti-Platt

·      effective (recurrence 4%)

·      limits ER

Bristow

·      transfer of coracoid with attached conjoint tendon to anterior surface of glenoid through transverse rent in subscapularis

·      rationale is

·      coracoid acts as bone block

·      conjoint tendon acts as dynamic sling when arm Abd and ER

·      prevents lower portion of subscapularis from riding superiorly with abduction

·      excellent results (redislocation 1.5%)

·      problems with

·      screw

·      potential injury to musculocutaneous nerve

·      distortion of normal anatomy

·      loss of ER

Bankart

·      Perthes (1906), Bankart (1939)

·      repair of anterior capsule to bone of anterior glenoid through drill-holes

·      numerous modifications

·      advantages

·      directly addresses pathology

·      allows intraoperative modification with capsular shift if only capsular redundancy found

·      no significant loss of ER

·      good results (3% redislocation)

·      65% can return to preinjury level of activity

Arthroscopic

·      in form of

·      staple capsulorrhaphy

·      suture repair of Bankart

·      variable results

·      average 20% failure rate

·      may become technique of choice

Technique of Bankart repair

·      beachchair position

·      use deltopectoral approach

·      tip of coracoid to apex of axilla

·      take cephalic vein laterally with deltoid

·      partially detach conjoint tendon from coracoid

·      partially release pectoralis major tendon (1.5 cm)

·      identify subscapularis

·      rotator interval above

·      anterior circumflex humeral vessels below

·      open subscapularis by either

·      split subscapularis along fibres using diathermy

·      vertically divide fibres at musculotendinous junction

·      retract subscapularis to expose capsule

·      T-shaped incision in capsule

·      vertical limb laterally

·      horizontal limb extending medially to glenoid

·      if detached, labrum and/or capsule repaired to bony glenoid

·      traditionally through drill-holes in glenoid rim

·      currently metal or plastic suture anchors inserted into glenoid

·      bony glenoid roughened

·      labrum and capsule sutured down

·      if anterior capsular redundancy present, anterior capsular repair

·      flaps plicated together in cruciate fashion

·      subscapularis tacked together

·      wound closed over drain

·      postoperatively

·      shoulder immobiliser for 6 weeks

·      supervised elbow and hand exercises

·      passive and active elevation and external rotation

·      strengthening exercises at 8 weeks

·      return to sport or work at 12 weeks

Recurrent atraumatic anterior involuntary instability

·      similar to traumatic instability

·      differences

·      usually  associated with capsular laxity

·      only occasionally associated with Bankart lesion

·      often component of multi-directional instability

·      longer trial of nonoperative management

·      if surgery indicated, anterior capsular repair is procedure of choice

·      high failure rate with extra-articular procedures