Biomechanical evaluation of graft fixation techniques for acromioclavicular joint reconstructions using coracoclavicular tendon grafts.
BACKGROUND
This study compared the initial strength of acromioclavicular joint reconstructions using coracoclavicular tendon grafts using interference screws, a tendon square knot, or side-to-side suturing for graft fixation.


METHODS
An acromioclavicular joint reconstruction was performed using a hamstring allograft looped under the coracoid and then fixed using interference screws, a square knot in the graft, and side-to-side graft suturing in each of 8 cadaveric shoulders. Each reconstruction was cycled in a superior direction, and displacements were recorded. Stiffness and ultimate load to failure of the reconstructions were determined.


RESULTS
The knot construct had a greater elongation after cycling compared with the screw (P = .003) or side-to-side suture (P = .001) repairs and had a higher ultimate load to failure than the screw construct (614.9 ± 124.6 vs 469.79 ± 175.1 N; P = .02). No significant differences were found between the screw and side-to-side suture constructs in elongation (P = .11) or ultimate loads to failure (P = .58). Finally, the side-to-side construct was significantly stiffer than the screw (P = .01) or knot (P = .01) reconstructions.


CONCLUSIONS
Clavicular fixation of a coracoclavicular graft during an acromioclavicular joint reconstruction using a square knot has superior ultimate strength compared with interference screw fixation. Side-to-side suture and screw constructs have superior cyclic displacement properties compared with knot fixation, with no differences in cyclic properties found between the side-to-side suture and screw constructs. Side-to-side suturing provides equivalent initial biomechanical strength compared with interference screw fixation.
Department of Orthopaedics, University of Utah School of Medicine, Salt Lake City, UT 84108, USA. robert.tashjian@hsc.utah.edu
Robert Z
RZ
Tashjian
Jodi D
JD
Southam
Todd
T
Clevenger
Kent N
KN
Bachus
D020341:Absorbable Implants; D000173:Acromioclavicular Joint / Q000503:physiopathology / Q000601:surgery*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002102:Cadaver; D002968:Clavicle / Q000601:surgery*; D006801:Humans; D019651:Plastic Surgery Procedures / Q000379:methods*; D013536:Suture Techniques / Q000295:instrumentation*; D013710:Tendons / Q000637:transplantation*