The Function of the Acromioclavicular and Coracoclavicular Ligaments in Shoulder Motion

Background: Scapulothoracic dyskinesis is an important consequence of acromioclavicular joint dislocations. However, no reports have described changes in 3-dimensional motions of the scapula and clavicle with respect to the thorax caused by acromioclavicular joint dislocation. Hypothesis: Sectioning of the acromioclavicular (AC) and coracoclavicular (CC) ligaments affects scapular and clavicular motion in a whole-cadaver model. Study Design: Controlled laboratory study. Methods: We evaluated shoulder girdle motion (scapula, clavicle, and humerus) relative to the thorax of 14 shoulders from 8 whole cadavers after sequential sectioning of the AC and CC ligaments (trapezoid and conoid ligaments). An electromagnetic tracking device measured 3-dimensional kinematics of the scapula and clavicle during humerothoracic elevation in the coronal and sagittal planes and adduction in the horizontal plane. Results: Sectioning of the AC ligament increased clavicular retraction during sagittal plane elevation and horizontal plane adduction. Sectioning of the trapezoid ligament decreased scapular external rotation during sagittal plane elevation and horizontal plane adduction. Sectioning of the conoid ligament decreased scapular posterior tilting during sagittal plane elevation and horizontal plane adduction. Acromioclavicular and CC ligament sectioning also delayed clavicular posterior rotation and increased clavicular upward rotation during coronal plane elevation. Conclusion: Our study revealed that AC and CC ligament disruption affected in vitro shoulder girdle kinematics in the whole-cadaver model. Clinical Relevance: The results of this cadaveric study revealed that AC and CC ligament disruption could cause dyskinesis of the scapula and clavicle. The kinematic changes could be a potential source of pain and dysfunction in the shoulder with AC joint dislocation, and therefore surgical reconstruction may be indicated in certain patients.

Download Full-text

Recurrent acromioclavicular joint dislocation with an associated coracoid fracture following acromioclavicular joint reconstruction

Annals of The Royal College of Surgeons of England ◽

10.1308/rcsann.2020.0051 ◽

2020 ◽

Vol 102 (6) ◽

pp. e136-e140

Author(s):

M Karia ◽

N Al-Hadithy ◽

G Tytherleigh-Strong

Keyword(s):

Acromioclavicular Joint ◽

High Strength ◽

Shoulder Girdle ◽

Coracoid Process ◽

Acromioclavicular Joint Dislocation ◽

Shoulder Injuries ◽

Overhead Athletes ◽

Joint Dislocations ◽

Synthetic Ligament ◽

Acromioclavicular Joint Instability

Acromioclavicular joint injuries are common and account for up to 12% of all shoulder girdle injuries and have been reported as being as high as 50% in sports-related shoulder injuries. While the majority of acromioclavicular joint dislocations can be treated non-operatively, there are certain injury configurations, which can include high-grade dislocations in overhead athletes, where surgery may be indicated. The surgical management of acromioclavicular joint instability has moved towards recreating the action of the coracoclavicular ligaments by resuspending the clavicle on to the coracoid. Multiple techniques using high-strength sutures, synthetic ligaments, tendon allografts or autografts passed either around or through the coracoid process have been described. However, an unusual, but significant, complication associated with these techniques is an iatrogenic fracture of the coracoid process. We report the case of a patient with an iatrogenic coracoid fracture following two failed acromioclavicular joint resuspensory reconstructions using a synthetic ligament. This injury was successfully treated with an autologous hamstring graft reconstruction, initially protected with a hook plate.

Download Full-text