title: Biomechanical analysis of distal clavicle excision with acromioclavicular joint reconstruction.
abstract: BACKGROUND
  Acromioclavicular (AC) joint separation is a common injury, usually affecting young adults. Controversy exists regarding whether to excise the distal clavicle when surgical intervention is required.
  
  
  OBJECTIVE
  To evaluate the biomechanical strength of AC and coracoclavicular (CC) ligament reconstruction with and without concurrent distal clavicle excision.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Nine matched pairs of cadaver shoulders were used. All shoulders were tested with intact CC and AC ligaments, and the ligaments were sectioned. For 1 shoulder in each pair, a 7-mm distal clavicle excision was performed. The contralateral distal clavicle was left intact. Single-tunnel CC ligament reconstruction was performed, and excess graft length was extended and secured across the AC joint to reconstruct the superior AC joint ligaments in all specimens. Specimens were then potted and cyclically loaded for 500 cycles in the anterior-posterior and superior-inferior planes using an MTS Minibionix load frame to evaluate displacement across the AC joint.
  
  
  RESULTS
  Regarding the clavicle-intact reconstructed versus the intact state, there was significantly greater AC joint translation in the reconstructed state in the anterior-posterior (20.2 ± 7.0 mm vs 6.0 ± 1.5 mm; P < .001) and superior-inferior directions (12.3 ± 3.3 mm vs 4.2 ± 1.2 mm; P < .001). In the clavicle-excised reconstructed versus the intact state, there was also significantly greater translation in the reconstructed state in the anterior-posterior (21.7 ± 5.1 mm vs 8.9 ± 4.3 mm; P < .001) and superior-inferior directions (12.3 ± 6.1 mm vs 5.8 ± 3.1 mm; P < .001). When the difference in translation between the reconstructed and intact groups in the clavicle-intact versus the clavicle-excised group was compared, no statistically significant difference was noted in anterior-posterior (14.2 ± 7.8 mm vs 12.8 ± 5.0 mm; P = .67) or superior-inferior translation (8.1 ± 2.9 mm vs 6.6 ± 3.9 mm; P = .39).
  
  
  CONCLUSIONS
  Excision of the distal clavicle did not have a significant effect on anterior-posterior or superior-inferior motion at the AC joint following single-tunnel CC and AC ligament reconstruction.
  
  
  CONCLUSIONS
  The study suggests that excision of the distal clavicle in this procedure is not associated with increased anterior-posterior or superior-inferior instability in this model.
authors.affiliation: Department of Orthopaedic Surgery, MedStar Union Memorial Hospital, Baltimore, Maryland, MD 21218, USA.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Beaver
authors.forename: Brent G
authors.initials: BG
authors.lastname: Parks
authors.forename: Richard Y
authors.initials: RY
authors.lastname: Hinton
mesh_terms: D000173:Acromioclavicular Joint / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002968:Clavicle / Q000601:surgery*; D006801:Humans; D008875:Middle Aged
keywords: acromioclavicular joint separation; distal clavicle excision; reconstruction; shoulder; translation