ACJ Dislocation



Acromioclavicular Ligaments


ACJ capsule

- strongest superiorly

- provides sigificant horizontal and AP stability

- injury allows some superior migration of clavicle in Type II injury


Coracoclavicular Ligaments / CCL


CC ligs anatomy


Primary restraint to superior translation

- primary suspensory ligament of upper limb


Trapezoid Ligament (anterolateral)

- anterolateral on coracoid

- almost horizontal in sagittal plane

- inserts trapezoid ridge

- primary restraint to axial compression


Conoid Ligament (posteromedial)

- postero-medial to trapezoid

- vertical inverted cone

- inserts conoid tubercle apex of posterior clavicular curve and junction lateral & medial 2/3

- primary restraint to superior and anterior translation



ACJ anatomy



AC joint


Diarthrodial synovial joint with hyaline cartilage

- has fibrocartilage intra-articular disc

- complete or incomplete

- usually degeneration by 4th decade


Clavicle may lie superior to acromion in normal population



- rotates 5-8o with scapulo-thoracic joint motion

- rotates 40o with shoulder abduction and elevation

- motion is at rather than ACJ




Usually direct force onto adducted shoulder joint

- clavicle remains in normal position

- arm falls down




Significant injuries clinically obvious

Step at the AC joint compared with other side

Tender at AC joint


Grade 3 ACJGrade 3 ACJ


Allman grades I-III 1967 / Rockwood modified 1989 Classification


I     AC ligament sprained, but CC ligaments intact (xray normal)


II    AC ligament disrupted, CC ligaments sprained but intact (displaced < 100% clavicle width)


ACJ Dislocation Grade 2Type II AC joint dislocation


III  AC & CC ligaments ruptured (displaced up to 100% of clavicular width)


Grade 3 ACJ Dislocation


IV   AC and CC ligaments disrupted and clavicle displaced posteriorly into trapezius

- can be easily missed

- need axillary lateral


Type IV ACJ APType IV ACJ Axillary LateralType IV ACJ


V    High dislocation (100 - 300%) - disrupted trapezius & deltoid and end of clavicle subcutaneous


ACJ Dislocation Type 5


VI    Subcoracoid dislocation


ACJ dislocation subcoracoid






Ringenberg et al J Should Elbow 2018

- 50 xrays reviewed by 6 upper limb trained orthopaedic surgeons

- inter-observer reliability fair (0.28)

- intra-observer reliability moderate (0.47)

- 4/50 images classified the same by all 6 surgeons




Cho et al J Should Elbow 2014

- 28 cases with xray and 3D CT and 10 surgeons

- inter-observer reliability slight (0.18)

- intra-observer reliability moderate (0.57)

- addition of 3D CT did not improve reliability




Zanca view

- specific for AC joint

- 10o cephalad, 50% underpowered


Stress views

- hold weights in each arm

- bilateral xray



- 50% of population overriding clavicle

- 2% under riding

- 29% incongruent

- joint width 0.5-7 mm






A.  Useful in professional athletes

- can distinguish between partial (type II) and complete (type III) CC ligament injuries

- allows prognosis

- can also distinguish type V


B.  Incidence of concomitant GHJ injuries with ACJ dislocation


Shah et al Orthop J Sports Med 2020

- MRI of 62 patients with acute ACJ dislocation

- 77% had an intra-articular injury

- 72% SLAP tears, 24% anterior labral tears, 5% posterior labral tears, 3% supraspinatus tears




Non operative


Type I and II


White et al Orthop J Sports Medicine 2020

- return to sport in 24 professional hockey players

- 3 weeks for grade 1/II

- 4 weeks for grade III


Type III / IV


Tamaoki et al Cochrane Database 2019

- acute type III dislocation

- 5 randomized and 1 quasi-randomized RCT with 357 patients

- no difference in outcomes with surgery


Canadian Orthopedic Trauma Society J Orthop Trauma 2015

- RCT of hook plate fixation for acute grade III, IV, V

- 83 patients

- no difference in outcome at 6, 12 or 24 months


Murray et al. JBJS Am 2018

- suspensory fixation for acute grade III, IV

- 60 patients

- no difference in outcome at 1 year






Type VI (subcoracoid)

Chronic debilitating Type III / IV failing non operative treatment

? Type V


Acute treatment




1.  Hook plate

2.  Suspensory coracoclavicular fixation - open or arthroscopic



- in the acute setting, reduce and hold ACJ

- AC and CC ligaments can heal


Pan et al Orthop Surg 2020

- meta-analysis of tightrope v hook plate for acute ACJ dislocation

- 4 studies, 179 patients

- no difference in outcome

- less postoperative pain with tightrope




Should hook plate / tightrope be supplemented with reconstruction in acute setting?


1.  Hook plate


Clavicle Hook PlateHook plate synthes




Reduction of ACJ

- hook under posterior acromion

- allows CC ligaments to heal

- need to remove plate at 4 - 6 months


Synthes technique pdf




Subacromial erosion - may be reduced by increasing the angle on the hook

Hook plate cut out through acromion - need to remove hook plate at 6 - 8 weeks

Clavicle fracture at end of plate


Clavicle Hook Plate Fracture




Hemmann et al Arch Orthop Trauma Surg 2021

- 99 patients with acute ACJ dislocation treated with hook plate

- average loss of reduction of 4 mm after hook plate removal

- nearly all good to excellent outcome

- 68% full ROM post operatively


Kim et al J Orthop Trauma 2021

- 35 patients treated with hook plate

- CT showed average 5 mm of subacromial erosion (50% acromial thickness)




Do you need to reconstruction the CC ligaments in the acute setting?


Yin et al Int J Surg 2018

- RCT of acute ACJ dislocation

- 26 hook plate and suture repair CCL

- 25 hook plate and ligament reconstruction CCL

- improved outcomes and satisfaction rates in hook plate + ligament reconstruction group


2.  Suspensory fixation


ACJ Reconstruction TightropeACJ Reconstruction TightropeACJ tightrope arthrex




Open or arthroscopic

- drill hole in clavicle

- centred drill hole in coracoid (to avoid fracture)

- reduce AC joint

- tighten suspensory fixation


Vumedi open technique video


Arthrex tightrope arthroscopic technique video


Vumedi arthroscopic technique video




Coracoid - must center the drill hole in the coracoid

Clavicle fracture

Failure tightrope construct


Failed ACJ surgery




Shin et al Arthroscopy 2015

- 18 patients with acute ACJ dislocation treated with Tightrope

- 1 case clavicle fracture

- 3 cases of clavicle or coracoid button failure

- 3 cases of clavicular bony erosion


Chronic ACJ Reconstruction




1.  Coracoclavicular ligament reconstruction

- anatomic or non anatomic

- autograft or allograft

- open or arthroscopic

- may be augmented with hook plate or suspensory fixation


2.  Weaver Dunn


Historical options


Excision distal clavicle

- poor results

- convert long high riding clavicle to short high riding clavicle


Phimister technique

- K wires across AC joint

- suture repair AC and CC ligaments

- risk of K wire migration


Bosworth screw

- screw from clavicle to coracoid

- risk of pullout

- needs to be removed


1.  CC ligament reconstruction


Anatomic technique

- pass allograft or autograft around coracoid

- pass through two clavicle drill holes

- secure with screws

- looking to improve AP and vertical stability

- risks clavicle fracture


CCL anatomic reconstruction


Non anatomic technique

- pass allograft or autograft around coracoid

- around clavicle


Vumedi open anatomic technique video


Vumedi arthroscopic anatomic technique video


Post Weaver Dunn with Lars Ligament



- fixation such as hook plate or suspensory fixation




Millett et al Arthroscopy 2015

- 31 shoulders anatomical reconstruction tendon graft

- 2/31 clavicle fractures

- 2/31 graft rupture attenuation

- 7/31 (22%) required secondary surgical procedure


2.  Weaver Dunn Reconstruction




Reconstruction of CC ligament with coraco-acromial ligament (CAL)



- 45o beach chair

- sabre incision over ACJ

- split deltoid fascia transversely along the clavicle and onto acromion

- expose distal end of clavicle and resect small amount  with microsagittal saw

- expose anterior aspect of acromion but identify and preserve CA ligament

- take off anterior 5mm of acromion with CA ligament attached

- carefully peel CAL off the underlying subscapularis

- CA ligament left attached to coracoid

- transferred from acromion to clavicle end

- intra-osseous suture repair through clavicle drill holes

- consider supplement fixation with hook plate / suspensory fixation


Type VI / Subcoracoid dislocation


ACJ dislocation subcoracoidACJ subcoracoid


Rare / can be missed


Risk of neurovascular injury / high velocity injury / associated with multi-traumas


Requires open reduction and fixation

- will have to release soft tissue off coracoid if not already avulsed

- i.e. pectoralis minor / coracoacromial ligament

- attempt to reduce with lateral traction of arm

- may need to release conjoint / perform coracoid osteotomy

- stabilize as needed