What is the classification of the acromioclavicular joint?
The acromioclavicular joint is a diarthrodial joint defined by the lateral clavicle articulating with the acromion process as it projects anteriorly off the scapula. The AC joint is a plane type synovial joint, which under normal physiological conditions allows only gliding movement.
What is Rockwood classification?
The Rockwood classification of AC joint separations uses plain radiographs to describe varying degrees of soft tissue involvement and joint displacement. Rockwood expanded on previous classification systems of AC joint separations to provide a more-detailed description based on pathoanatomy of the injury.
What is acromioclavicular interval?
The acromioclavicular interval is normally 1–3 mm in width whereas the coracoclavicular interval should be 11–13 mm [7]. An acromioclavicular interval greater than 6–7 mm or a difference in acromioclavicular interval of greater than 2–3 mm between left and right sides are considered pathologic.
What is AC joint widening?
Widening of the AC joint, step off deformity at the AC joint, and increase in the CC distance (common range 1.1-1.3 cm) are indicative of AC joint injury (Figure 1). Increase of CC distance of 25-50% over the normal side on a bilateral Zanca view indicates complete CC ligament disruption.
What is a acromioclavicular joint?
The acromioclavicular, or AC, joint is a joint in the shoulder where two bones meet. One of these bones is the collarbone, or clavicle. The second bone is actually part of the shoulder blade (scapula), which is the big bone behind the shoulder that also forms part of the shoulder joint.
Why is the acromioclavicular joint atypical?
It has two atypical features: 1. The articular surfaces of the joint are lined with fibrocartilage (as opposed to hyaline cartilage). The hyaline articular cartilage becomes fibrocartilage on the acromial side of the joint by the age of 17 years and on the clavicular side by the age of 24 years.
What is normal acromioclavicular distance?
In adults, the normal acromioclavicular joint space is 1 to 3 mm wide [16] and diminishes with increasing age [13]. The average distance between the clavicle and coracoid process is between 1.1 and 1.3 cm [1, 5].
What is AC joint Diastasis?
Also known as the AC joint, the injury occurs with a partial or complete tearing of the ligaments found near the top of the shoulder where the clavicle or collarbone meets the upper end or acromion of the scapula, or shoulder blade.
What are 3 main ligaments that make up the acromioclavicular joint?
Acromioclavicular (AC) joint
| Type | Synovial plane joint; multiaxial |
|---|---|
| Ligaments | Intrinsic: Superior acromioclavicular ligament, inferior acromioclavicular ligament Extrinsic: Coracoclavicular ligament (with conoid and trapezoid parts) |
| Innervation | Lateral pectoral nerve, suprascapular nerve |
What is the Rockwood classification of acromioclavicular injuries?
The Rockwood classification of acromioclavicular injuries in adults is as follows [ 10, 1, 8, 9] : Type I: Minor sprain of the acromioclavicular ligament, intact joint capsule, intact coracoclavicular ligament, intact deltoid and trapezius
What are the three types of acromioclavicular separations?
As noted earlier, type III, IV, V, and VI acromioclavicular separations are double disruptions of the superior shoulder suspensory complex (SSSC). [ 8, 9, 11]
When does a type II acromioclavicular sprain occur?
Type II sprains are seen when a heavier force is applied to the shoulder, disrupting the acromioclavicular ligaments but leaving the sprained coracoclavicular ligaments intact. [ 8, 9, 11] When these injuries occur, the lateral clavicle becomes a little more prominent.
What’s the difference between Type I and Type II acromion?
The type I acromion, which is flat, is the “normal” acromion. The type II acromion is more curved and downward dipping, and the type III acromion is hooked and downward dipping, obstructing