Decreased Coracoclavicular Distance
A decreased coracoclavicular distance most commonly indicates acromioclavicular (AC) joint disruption with superior displacement of the clavicle, requiring urgent orthopedic evaluation for displaced fractures or high-grade AC separations, with surgical reconstruction indicated when coracoclavicular ligament disruption is present. 1
Clinical Implications
A decreased coracoclavicular distance represents an abnormal anatomic relationship between the clavicle and coracoid process, typically resulting from:
- AC joint dislocation with coracoclavicular ligament disruption, which destabilizes the clavicle and allows superior migration 2, 3
- Displaced lateral clavicle fractures involving the coracoclavicular ligament complex 1
- Iatrogenic instability following excessive distal clavicle resection, particularly affecting horizontal plane stability 4
The functional consequences are significant because the clavicle serves as a critical strut that stabilizes external rotation, upward rotation, and posterior tilting of the scapula during arm movement. 5 Loss of this function impairs glenohumeral joint motion and may contribute to subacromial impingement. 5
Diagnostic Approach
Obtain upright radiographs rather than supine views, as they better demonstrate the true degree of displacement and coracoclavicular distance abnormalities. 6, 1 Standard trauma radiographs should include anteroposterior views in internal and external rotation plus an axillary or scapula-Y view, as AC joint dislocations can be misclassified on AP views alone. 6
Measure the coracoclavicular distance on anteroposterior radiographs and compare to the contralateral side. 2, 3 A coracoclavicular distance ratio (affected/unaffected side) >25% indicates significant loss of reduction. 3
Treatment Algorithm
Surgical Indications
Surgical treatment is indicated for displaced lateral clavicle fractures with disruption of the coracoclavicular ligament complex. 1 This represents a critical decision point because these injuries have high rates of nonunion and symptomatic malunion with conservative management. 6
Additional surgical indications include:
- Displacement >100% (no cortical contact between fragments) requiring urgent orthopedic follow-up 1
- Shortening exceeding 1.5cm in displaced midshaft fractures 1
- Iatrogenic AC joint instability with decreased distal clavicle bone stock 4
Surgical Options
For coracoclavicular ligament reconstruction:
- Anatomic coracoclavicular ligament reconstruction using autogenous tendon graft provides successful long-term outcomes when proper tunnel placement is achieved 3
- Critical technical consideration: Decrease the clavicular tunnel anteroposterior angle and ensure anatomic placement of both clavicular and coracoid tunnels to prevent loss of reduction 3
- Bony augmentation with iliac crest autograft may be necessary when distal clavicle bone stock is insufficient, particularly in iatrogenic instability 4
For clavicle fractures with coracoclavicular ligament disruption:
- Plate fixation using manufacturer-contoured anatomic clavicle plates, with anterior inferior plating potentially offering lower implant removal rates 1
- Intramedullary nailing provides equivalent long-term outcomes to plate fixation 1
Conservative Management
For minimally displaced injuries without coracoclavicular ligament disruption:
- Sling immobilization for 4-6 weeks (preferred over figure-of-eight brace) 1, 7
- Discontinue sling by 4 weeks for routine activities while avoiding lifting, pushing, or pulling 1, 7
- Full weight-bearing activities allowed at 8-12 weeks based on radiographic healing 1, 7
Critical Pitfalls
Loss of reduction occurs in 47% of cases following single-tunnel coracoclavicular ligament reconstruction with autogenous tendon graft, with a 20% complication rate including distal clavicle fractures through the tunnel. 2 Complications significantly worsen clinical outcomes. 2
Posterior AC joint displacement is associated with unfavorable outcomes and occurs when the clavicular tunnel anteroposterior angle is excessive. 3 Proper tunnel orientation is essential for maintaining reduction.
Smoking increases nonunion rates and leads to inferior clinical outcomes in clavicle fractures. 1 This should be addressed preoperatively.
Rare Anatomic Variant
The coracoclavicular joint (a synovial joint between the conoid tubercle and coracoid process) occurs in approximately 2.5% of the population and is typically asymptomatic. 8 When symptomatic, it presents as anterior shoulder pain with extreme abduction and responds to steroid injection or surgical excision. 8 This should not be confused with pathologic decreased coracoclavicular distance from trauma.