In AC joint sprain classification, which type describes a disrupted AC ligament with a sprained CC ligament and distal clavicle unstable?

In AC joint sprain classification, which type describes a disrupted AC ligament with a sprained CC ligament and distal clavicle unstable?

• A. Type 1
• B. Type 2
• C. Type 3
• D. Type 4

Answer: (B)

Stability at the AC joint depends on two ligament systems: the acromioclavicular (AC) ligaments that cross the joint for horizontal stability, and the coracoclavicular (CC) ligaments (conoid and trapezoid) that suspend the clavicle from the coracoid for vertical stability. When the AC ligaments are disrupted but the CC ligaments are only sprained, the joint loses some horizontal and vertical restraint, but the CC structures aren’t completely torn. This leads to mild to moderate instability of the distal clavicle, with displacement that is less dramatic than in injuries where the CC ligaments are fully ruptured. This pattern is distinct from a simple AC sprain (AC ligaments intact, little to no distal clavicle movement) and from injuries where both AC and CC ligaments are completely torn (more pronounced clavicular displacement and greater instability). Therefore, a disrupted AC ligament with a sprained CC ligament producing distal clavicle instability best matches this intermediate injury pattern.

Stability at the AC joint depends on two ligament systems: the acromioclavicular (AC) ligaments that cross the joint for horizontal stability, and the coracoclavicular (CC) ligaments (conoid and trapezoid) that suspend the clavicle from the coracoid for vertical stability. When the AC ligaments are disrupted but the CC ligaments are only sprained, the joint loses some horizontal and vertical restraint, but the CC structures aren’t completely torn. This leads to mild to moderate instability of the distal clavicle, with displacement that is less dramatic than in injuries where the CC ligaments are fully ruptured.

This pattern is distinct from a simple AC sprain (AC ligaments intact, little to no distal clavicle movement) and from injuries where both AC and CC ligaments are completely torn (more pronounced clavicular displacement and greater instability). Therefore, a disrupted AC ligament with a sprained CC ligament producing distal clavicle instability best matches this intermediate injury pattern.