title: Mechanics of coracoacromial ligament transfer augmentation for acromioclavicular joint injuries.
abstract: The objective of this study was to determine how effectively the Weaver-Dunn repair (both unaugmented and augmented with a suture and suture anchor) restores joint translation in response to applied loads to normal. Translation of a reference point on the clavicle relative to a reference point on the acromion was assessed in five cadaver shoulders by applying anterior, posterior and superior loads of 50 N to the clavicle using a specially designed test rig while measuring movement of the acromion and clavicle with an optical measurement system. Translation was determined for the intact joint, after simulated injury and Weaver-Dunn repair, and after augmentation of the Weaver-Dunn repair with a suture fixed to a suture anchor in the coracoid process. Joints were significantly more mobile after Weaver-Dunn repair (16.1 mm anterior, 15.7 mm posterior, 11.1 mm superior) than when intact (4.1 mm anterior, 3.2 mm posterior, 4.0 mm superior) (p < 0.005). Augmentation with a suture and suture anchor reduced separation of the Weaver-Dunn reconstruction significantly (to 5.3 mm anterior, 4.1 mm posterior, 2.0 mm superior) (p < 0.005). Joints reconstructed using an augmented Weaver-Dunn repair were not significantly more (or less) mobile than normal joints (p > 0.005), although the power of the test to detect this difference was low (power = 0.107). We anticipate that, when surgery is indicated for treating acromioclavicular joint injury, an augmented Weaver-Dunn reconstruction will yield a joint that is less painful, more functional and less likely to require revision.
authors.affiliation: Orthopaedic Biomechanics Laboratory, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA. dawilson@interchange.ubc.ca
authors.forename: David R
authors.initials: DR
authors.lastname: Wilson
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Moses
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Zilberfarb
authors.forename: Wilson C
authors.initials: WC
authors.lastname: Hayes
mesh_terms: D000173:Acromioclavicular Joint / Q000293:injuries* / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D002968:Clavicle; D004867:Equipment Design; D005260:Female; D006801:Humans; D008022:Ligaments / Q000601:surgery*; D019563:Mechanics; D008954:Models, Biological; D009985:Orthopedics / Q000379:methods; D013048:Specimen Handling; D016474:Weight-Bearing