Sagittal orientation of coracoclavicular ligament reconstruction affects the stability of surgical repair

Subject-specific computational modeling of acromioclavicular and coracoclavicular ligaments

BACKGROUND

Disruption of the acromioclavicular joint is a common injury. Despite the different surgical procedures described for treating this injury, complications such as loss of reduction and failure of fixation remain unacceptably high. We developed a computer model of the acromioclavicular joint to better understand the biomechanical contributions of the ligaments that are typically injured.

METHODS

Six fresh frozen human cadaveric shoulders were tested on an AMTI VIVO 6-degree of freedom test platform to measure force-displacement in inferior translation, anteroposterior translation, and internal rotation before and after sequentially transecting the coracoclavicular and acromioclavicular ligaments. These data were used to construct computer models of each specimen. Three-dimensional computed tomographic scans were used to generate a rigid-body dynamics model using the AnyBody Modeling System. The scapula and clavicle were connected by the acromioclavicular joint capsule, the conoid ligament, and the trapezoid ligament. Subject-specific ligament properties were calculated by matching computer predictions to experimental force-displacement data.

RESULTS

The calculated free lengths of the conoid, trapezoid, and acromioclavicular ligaments were 13.5 (±3.2), 11.8 (±2.4), and 11.0 (±2.7) mm, respectively. The calculated stiffnesses of the conoid, trapezoid, and acromioclavicular ligaments were 34.3 (±6.3), 28.4 (±3.2), and 33.8 (±8.2) N/mm, respectively. Root mean square deviation (RMSD) of predicted force-displacement curves relative to experimental force-displacement curves (during inferior and anteroposterior translation) was less than 1 mm. For validation of subject-specific models, after ligament properties were calculated, the RMSD of the predicted torque over 15° of internal rotation was 12% of maximum rotational torque (average for 6 specimens).

DISCUSSION AND CONCLUSION

Acromioclavicular disruption results in multidirectional instability, which requires careful consideration of the individual contributions of the injured ligaments. In addition, variations in patient anatomy can significantly affect the biomechanical stability of the reconstruction. Subject-specific models can enhance our understanding of the individual and collective biomechanical contributions of the injured soft tissues to the multiaxial stability of the acromioclavicular joint. These models may also be useful for analyzing and assessing biomechanical stability after various types of surgical reconstruction.

All-Arthroscopic Coracoacromial Ligament Transfer: The Modified Neviaser Procedure for Acromioclavicular Dislocations

Over the course of the years, the topic of optimizing the management of acromioclavicular joint dislocations has gained popularity, remaining a subject of debate. It has been determined that posterior horizontal instability appears to be one of the factors influencing both clinical and radiographic outcomes, postsurgical reconstructions with coracoclavicular techniques. In contrast, the acromioclavicular ligament complex (ACLC) has been experimentally demonstrated to play a crucial role in horizontal translation and rotational stability of the clavicle. Although several strategies have been established, perfect surgical timing, and its potential impact during the healing process, remain poorly defined. Furthermore, appropriate surgical techniques to restore normal acromioclavicular joint kinematics while ensuring an adequate biological environment remain unclear. Due to the existence of multiple features present in acromioclavicular joint reconstruction techniques, an ideal approach involves ACLC and coracoclavicular combination reconstruction, minimal clavicular drilling, and biological enhancement to ensure anatomical reduction and an adequate process of ligament healing. The purpose of this Technical Note is to present a modified surgical technique of the Neviaser procedure. This modified surgical technique combines an all-arthroscopic single tunnel coracoclavicular fixation with the transfer of the coracoacromial ligament to reconstruct the ACLC.