Background: Reconstruction of only the coracoclavicular (CC) ligaments may restore superior-inferior (S-I) but not anterior-posterior (A-P) stability of the acromioclavicular (AC) joint. Concomitant reconstruction of both the AC and CC ligaments may more reliably restore intact biomechanical characteristics of the AC joint. Methods: Ten matched pairs of shoulders were utilized. Five specimens underwent CC ligament reconstruction while an equal number underwent combined AC and CC ligament reconstruction utilizing an intramedullary tendon graft. Each of the reconstructions was compared with the intact contralateral control. Translational and load to failure characteristics were compared between groups. Results: No difference was found in S-I translation between intact specimens and CC-only reconstructions (P=.20) nor between intact specimens and AC/CC reconstructions (P=.33) at 10 Newton (N) loads. Significant differences were noted in A-P translation between intact specimens and CC-only reconstructions (P<.001) but no difference in A-P translation between intact specimens and AC/CC reconstructions (P=.34). Conclusion: The A-P and S-I translational biomechanical characteristics of the AC joint were restored using the new technique described. Reconstruction of the CC ligaments only (versus AC/CC combined) led to significantly increased translational motion in the A-P plane as compared to intact control specimens.