Stability of acromioclavicular joint reconstruction: biomechanical testing of various surgical techniques in a cadaveric model.
BACKGROUND
Despite reports of excellent results with the Weaver-Dunn coracoacromial ligament transfer, many authors recommend augmenting the transfer with supplemental fixation. The authors of this study sought to determine whether there is a biomechanical basis for this assertion and which augmentative method, if any, most closely restored acromioclavicular motion to normal.


OBJECTIVE
Augmentative coracoclavicular fixation provides better restoration of normal acromioclavicular joint laxity and an increased failure load when compared with the Weaver-Dunn reconstruction alone.


METHODS
Controlled laboratory cadaveric study.


METHODS
Native acromioclavicular joint motion was measured using an infrared optical measurement system. Acromioclavicular and coracoclavicular ligaments were then cut, and 1 of 6 reconstructions was performed: Weaver-Dunn, suture cerclage, and 4 different suture anchors. Acromioclavicular joint motion was reassessed, a cyclic loading test was performed, and the failure load was recorded.


RESULTS
After Weaver-Dunn reconstruction, mean anteroposterior laxity increased from 8.8 +/- 2.9 mm in the native state to 41.9 +/- 7.6 mm (P < or = .01), and mean superior laxity increased from 3.1 +/- 1.5 mm to 13.6 +/- 4.4 mm (P < or = .01). Weaver-Dunn reconstructions failed at a lower load (177 +/- 9 N) than all other reconstructions (range, 278-369 N) (P < or = .05). Reconstruction using augmentative fixation allowed less acromioclavicular motion than Weaver-Dunn reconstruction (P < or = .05) but more motion than the native ligaments (P < or = .05). Specifically, mean superior laxity after reconstruction ranged between 6.5 and 9.0 mm compared with the native ligaments (3.1 +/- 1.5 mm) and the Weaver-Dunn reconstructions (13.6 +/- 4.4 mm). Mean anteroposterior laxity after the reconstructions tested ranged between 21.8 and 33.2 mm, compared with the native ligaments (8.8 +/- 2.9 mm) and the Weaver-Dunn reconstructions (41.9 +/- 7.6 mm).


CONCLUSIONS
Although none of the augmentative methods tested restored acromioclavicular stability to normal, all proved superior to the Weaver-Dunn reconstruction alone.


CONCLUSIONS
This study suggests that when performing acromioclavicular reconstruction, supplemental fixation should be used because it provides more stability and pull-out strength than the Weaver-Dunn reconstruction alone.
Department of Orthopaedics, Kaiser Permanente West Los Angeles Medical Center, Los Angeles, California, USA.
Ashwin V
AV
Deshmukh
David R
DR
Wilson
Jeffrey L
JL
Zilberfarb
Gary S
GS
Perlmutter
D000173:Acromioclavicular Joint / Q000293:injuries* / Q000601:surgery*; D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D005260:Female; D006801:Humans; D007593:Joint Instability; D008022:Ligaments / Q000473:pathology / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D016059:Range of Motion, Articular; D019651:Plastic Surgery Procedures / Q000379:methods*; D013536:Suture Techniques; D016474:Weight-Bearing