title: The effect of distal clavicle excision on in situ graft forces in coracoclavicular ligament reconstruction.
abstract: BACKGROUND
  Recently, some have suggested that the acromioclavicular articulation confers stability to the construct after coracoclavicular ligament reconstruction for acromioclavicular joint separation. Therefore, it has been suggested that distal clavicle excision should not be performed in this context to protect the graft during healing.
  
  
  OBJECTIVE
  Sectioning the acromioclavicular ligaments would significantly increase in situ forces of a coracoclavicular ligament graft, whereas performing a distal clavicle resection would not further increase in situ graft forces.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  A simulated coracoclavicular reconstruction was performed on 5 cadaveric shoulders. Static loads of 80 N and 210 N were applied directly to the clavicle in 5 directions: anterior, anterosuperior, superior, posterosuperior, and posterior. The in situ graft force was measured using a force transducer under 3 testing conditions: (1) intact acromioclavicular ligaments, (2) sectioned acromioclavicular ligaments, and (3) distal clavicle excision.
  
  
  RESULTS
  For both magnitudes of load, in all directions, in situ graft force with intact acromioclavicular ligaments was significantly less than that with sectioned acromioclavicular ligaments (P < .001). Distal clavicle excision did not further increase the in situ graft forces with load applied to the clavicle in an anterior, anterosuperior, or superior direction. However, in situ graft forces were increased with distal clavicle excision when the clavicle was loaded with 210 N in the posterosuperior direction (60.4 ± 6.3 N vs 52.5 ± 7.1 N; P = .048) and tended to be increased with posterior loading of the clavicle (71.8 ± 6.2 N vs 53.1 ± 8.8 N; P = .125).
  
  
  CONCLUSIONS
  Intact acromioclavicular ligaments protect the coracoclavicular reconstruction by decreasing the in situ graft force. The slight increase in the in situ graft force only in the posterosuperior and posterior direction after distal clavicle excision suggests only a marginal protective role of the acromioclavicular articulation. Further, the peak graft forces observed represent only a small fraction of the ultimate failure strength of the graft.
  
  
  CONCLUSIONS
  Distal clavicle excision can perhaps be safely performed in the context of coracoclavicular ligament reconstruction without subjecting the graft to detrimental in situ force. Although the acromioclavicular articulation serves only a marginal role in protecting the coracoclavicular ligament graft, reconstruction of the acromioclavicular ligaments may serve an important role in decreasing in situ graft force during healing.
authors.affiliation: Department of Orthopaedic Surgery, Lenox Hill Hospital, 130 E 77th Street, Black Hall 11th Floor, New York, New York, 10075, USA. marc.kowalsky@gmail.com
authors.forename: Marc S
authors.initials: MS
authors.lastname: Kowalsky
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Kremenic
authors.forename: Karl F
authors.initials: KF
authors.lastname: Orishimo
authors.forename: Malachy P
authors.initials: MP
authors.lastname: McHugh
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Nicholas
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Lee
mesh_terms: D000173:Acromioclavicular Joint / Q000293:injuries / Q000601:surgery*; D000328:Adult; D001696:Biomechanical Phenomena; D002102:Cadaver; D002968:Clavicle / Q000293:injuries / Q000601:surgery*; D005240:Feasibility Studies; D006801:Humans; D008023:Ligaments, Articular / Q000601:surgery*; D008297:Male; D016059:Range of Motion, Articular; D019651:Plastic Surgery Procedures / Q000295:instrumentation / Q000379:methods*; D012782:Shoulder / Q000601:surgery; D012785:Shoulder Joint / Q000601:surgery*; D018709:Statistics, Nonparametric; D014182:Transplantation, Autologous / Q000295:instrumentation / Q000379:methods