Os acromiale, Acromial # and acromial insufficiency

James Wilson

ST8 Trainee T&OUpper Limb Fellow

Wrightington Hospital

• Scapula ossified from 9 or more centres

• Body - 8 weeks

• Middle Coracoid 15-18 months

• Base coracoid

• Base acromion

• Inferior angle

• Tip of acromion

• Vertebral border

Embryology

• 1 Flat

• 2 Curved

• 3 Hooked

• 4 Convex

Morphology

• PA = Pre-acromion

• MSA = Meso-acromion

• MTA = Meta-acromion

• Meso and Meta-acromion junction most common

• Nomenclature

Os Acromiale

• Incidence 1.4-30%

• 33-62% bilateral

• Types - • 1: between meso and meta acromion

(typical)

• 2: between pre and meso acromion

• 3: between pre and meso as well as meta acromion

• 4: between all three ossification centres

Os Acromiale

• Presentation

• Signs and symptoms of impingement

• Night Pain

• Tenderness

• Indirect - Cuff tear

• Diagnosis

• Best seen on axillary view

Os Acromiale

• Nothing (if asymptomatic)

• Non operative

• Physiotherapy

• Injections

• Subacromial space

• intra-lesional

• Surgical • Excision

• Acromioplasty

• Fixation

Treatment

• Arthroscopic v’s Open excision

• Theoretically arthroscopic preserves the deltoid attachment • No comparative studies

• Pagnani - Arthroscopic excision 11 Mesoacromiales (18-25yrs)— return to sport and full strength by 14 weeks

• Wright - Arthroscopic excision 13 Mesoacromiales (Mean age 36) - full strength 26 weeks 85% satisfaction (11/13)

• Boehm et al and Warner et al performed open excision with deltoid reattachment. (4 pre and 5 meso)

• Boehm - similar outcomes to acomioplasty and fixation. • Warner - good outcomes with pre-os excision, poor

outcomes for meso-os excisions

Excision

• Abbound - mixture of open (5) and arthroscopic (6) acromioplasty of patients with a stable mess-os. Retrospective comparison with mixture of K-wire (5) and cannulated screw fixations (3) - no significant difference.

• Boehm - Open acromioplasty retrospectively compared with k-wire fixation - equivalent satisfaction and Constant scores

Acromioplasty

• Review found • Cannulated screw fixation 96% (23/24) • K-wire 63% (31/49)

• Union correlated with outcome and satisfaction scores

• Removal of metalware

• Cann screw 38%

• K-wire 88%

• Complications

• Deep infection - Open excision (1), Open acromioplasty (2), ORIF (1) all had I&D

• Superficial infection - ORIF (2) settled with ABx

Fixation

• Rare

• Mechanism

• Direct blow

• Avulsion due to deltoid

• Overuse

• Complication of reverse TSR

• Indications for fixation

• Symptomatic non-union

• Subacromial Impingement • >1cm displacement • Open injuries

• Multiple disruptions of the SSSC

Acromion fractures

• Posterior approach

• Lateral decubitous position

• Incision over posterior border of acromion and along spine

Fixation Technique

• Deltoid elevated off with infraspinatus to expose fracture

• Laminar spreader used to distract fragments to facilitate cleaning and reduction

Fixation technique

Fixation Technique

• Smaller lateral fractures can be fixed with a similar technique

• 2.7 screw with 2mm mini-fragment plate

Fixation Technique

• 457 RSA

• 5 centres

• 40 shoulders identified with acromial pathology

• Os Acromiale (23)

• Aquired acromial lesions (17)

• Non union scapula spine (1)

• Post operative scapula spine fracture (4)

• No acromial pathology (416)

Insufficiency