Anatomic Suture Reconstruction of the Acromioclavicular Joint is Noninferior to Traditional Suture Constructs: A Biomechanical Study

Author(s): Josiah A. Valk DO, Erik W. Dorthé, Darryl D. D’Lima, MD, PhD, Heinz R. Hoenecke Jr., MD

Background: Acromioclavicular (AC) joint injuries, especially in highgrade cases, can result in persistent instability despite surgical intervention. Traditional reconstructions focus on vertical stability by addressing the coracoclavicular (CC) ligaments but may neglect the horizontal and rotational stability provided by the AC ligament complex.

Purpose: This study evaluates the biomechanical performance of an anatomic suture-based AC ligament reconstruction technique compared to traditional suture constructs.

Methods: Twenty 3D-printed scapula and clavicle models were randomly assigned to four reconstruction techniques: O-frame, X-frame, O + X-frame, and anatomic AC ligament reconstruction. Using a six-axis robotic testing system, superior translation, posterior translation, and both anterior and posterior rotation were cyclically loaded, and stiffness (N or Nm) was recorded.

Results: The anatomic reconstruction demonstrated comparable stiffness to traditional constructs in superior translation, posterior translation, and anterior rotation (p > 0.05). Notably, it exhibited significantly higher stiffness in posterior rotation (0.75 ± 0.36) compared to the X-frame (0.29 ± 0.26) (p = 0.048). All constructs maintained structural integrity throughout cyclic loading, with no anchor pullout or gross failures.

Conclusion: Anatomic suture reconstruction of the AC joint provided equivalent biomechanical stability to traditional constructs in most tested directions and demonstrated superior stiffness in posterior rotation. These findings support the inclusion of anatomic AC ligament suture augmentation to address persistent horizontal and rotational instability, while suggesting that simplified suture-based reconstructions can be biomechanically robust in 3D-printed models.