Miscellaneous Conditions

Os Acromiale

Definition

  • Non-union of one of the acromion ossification centres

Aetiology

  • Acromion arises from 4 separate ossification centres
    • From anterior to posterior can be remembered as PASTA
    • Normally fuse between 18 & 25 years old
  1. Preacromium
  2. Mesoacromium
  3. MetaAcromium
  4. Basiacromium (at base)
  • Type of Os Acromiale
    • Described by ossification centre anterior to non-union
    • Mesoacromium is the most common
      • Failure of fusion between meso & metaacromium

Clinical Features

  • Most asymptomatic – incidental findings
  • May cause:
    • Impingement
    • Cuff weakness
    • Pain

Diagnosis

History

  • Usually insidious and atraumatic

Examination

  • Pain over acromion

XR

  • Axillary lateral view
  • Screen other side – 60% incidence of bilaterality

MRI

  • Is non-union ‘active’ – high signal, effusion/fluid etc.
  • Other pathology

Management

Non-surgical

  • Pain relief
  • Injection – diagnostic +/- therapeutic

Surgical

Fragment excision
- Poor results unless for small irreparable os acromiale

ORIF of Fragment & Bone Grafting
- With cannulated screws or tension band wire
- Bone grafting of non-union site

Arthroscopic treatment
- ASAD
- Treat other pathology
- Excision – for small unstable fragments

Outcomes

  • Best if proven to be symptomatic and treated with ORIF & bone grafting

Scapula Winging

Definition

  • Abnormal posture and motion of the scapula
  • Causes pain and dysfunction due to altered kinematics & power

Aetiology

Primary

  • Neurologic deficit of one of the three primary scapula stabilisers
    • (SA, Trapezius, RMa & RMi)
  • Uncommon

Secondary

  • Due to other shoulder pathology
    • GHJ, Bursal, Cuff, osteochondroma, etc.
  • More common

Pathoanatomy

Scapula

  • Largest bone of shoulder girdle
  • Covers 2nd – 7th ribs
  • Inferior, lateral, and superior angles
  • Lies 30° anteriorly rotated & 10° flexed at rest
  • Gives attachment to 17 muscles
    • Scapulothoracic, Scapulohumeral, Rotator cuff muscles

Scapulothoracic Stability

  • Muscle attachments
  • ACJ & Coracoclavicular ligaments
  • Allows huge range of movement with little constraint
  • Movements of scapula
  • GHJ: ST motion 2:1 during shoulder abduction
    • Scapula moves glenoid & acromion to prevent impingement
    • Facilitates large ROM
  • Elevation: Trapezius, Levator Scapulae
  • Protraction: Serratus Anterior, Pec Major & Minor
  • Retraction: Rhomboids

Serratus Anterior

  • Large flat muscle
  • Origin first 9 ribs
  • 3 separate groups of fibres – upper, middle, lower
  • Inserts on medial border scapula
  • Contraction = protraction of scapula

Nerve Supply

  • Long Thoracic Nerve
    • C5 & C6 contribution early → supplies upper fibres
    • C7 contribution below middle scalene → supplies middle & lower fibres
    • Courses under clavicle & 1st rib; then on chest wall in mid axillary line
    • Length of course is 20 cm and superficial throughout
    • Vulnerable to injury
    • Usually blunt or stretch injury
    • May be from C5-7 root problem
    • Chest drain insertion
    • Palsy = Medial Winging
    • Most common cause of primary winging

Trapezius

  • Superficial muscle
  • Origin: Occipital protuberance, Ligamentum nuchae & spinous processes of all cervical & thoracic vertebrae
  • Attaches to superior and medial border scapula
  • Elevates and tilts scapula medially

Nerve Supply

  • Spinal Accessory Nerve (Cranial Nerve XI)
    • Only cranial nerve to exit and re-enter skull
    • Enters Posterior triangle under SCM upper 1/3 & mid 1/3 border
    • Superficial and vulnerable to injury
    • Usually penetrating iatrogenic injury
    • Palsy = Lateral Winging

Rhomboids

  • Minor is superior to major

Minor

  • Origin: C7 & T1 spinous processes
  • Inserts on medial border at level of scapula spine

Major

  • Origin: T2-T5 spinous processes
  • Inserts on medial border down to inferior angle

Innervation

  • Dorsal Scapular Nerve
    • Pre-clavicular branch from C5 nerve root
    • Most commonly a neuropraxia
    • Entrapment under hypertrophic middle scalene muscle

Causes

Primary Neurologic

  • Entrapment, stretch, sharp trauma as above
  • Brachial Neuritis (Parsonage-Turner Syndrome)
  • Guillain-Barré Syndrome

Facioscapulohumeral Dystrophy

  • Autosomal Dominant
  • Abnormal face
  • Weak periscapular muscles
  • Relatively normal cuff and deltoid
  • Causes severe bilateral winging
  • Treatment: Non-operative or scapulothoracic fusion

Secondary Causes

  • GHJ, Cuff, Bursa impingement
  • Osteochondroma – snapping scapula
  • Scapulothoracic bursitis
    • Due to periscapular muscle fatigue caused by abnormal compensatory scapula motion for other shoulder pathology
    • Deranged muscle firing patterns

Diagnosis

History

  • Pain, dysfunction, ache, recent virus, trauma, other problems
  • Pain in back when sitting against chair
  • Winging causes shoulder weakness and dysfunction

Examination

  • Test muscles
  • Serratus Anterior
    • Press-ups against wall – can’t do or fatigues quickly
    • Medial winging
  • Trapezius
    • Shrug shoulders
    • Lateral Winging
  • Rhomboids
    • Hands on hips – squeeze elbows behind back
    • Lateral winging - milder
  • Look for secondary causes
  • Rule out Facioscapulohumeral dystrophy

Investigation

  • NCS & EMG if neurologic problem suspected
  • Plain XR
  • MRI
    • Screening for other pathology

Management

Non-operative

  • Primary usually resolves over 18 months
  • Appropriate treatment for secondary causes
  • Physio
  • Periscapular muscle strengthening

Surgical

  • If winging is symptomatic and interfering with ADLs or sport
  • Serratus Anterior Palsy
    • Pec Major Sternal Head Transfer
  • Trapezius Palsy
    • Eden-Lange Procedure
    • Move Levator Scapulae & Rhomboids to where Trapezius inserts
  • Rhomboid Palsy
    • Winging mild & doesn’t usually need treatment

Scapulothoracic Fusion

  • For failed surgical transfer
  • Facioscapulohumeral Dystrophy
  • Medial & Lateral Scapula Winging
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