Bernard Hopkins has been released from the California Hospital Medical Center in Los Angeles after being x-rayed and examined by Dr. Sam Thurber, MD who diagnosed Hopkins with a separation of the acromioclavicular (A-C) joint which connects the collar bone and shoulder blade.
More information on AC joint separation (taken from Wikipedia):
A common injury to the AC joint is dislocation, often called AC separation or shoulder separation. This is not the same as a "shoulder dislocation," which refers to dislocation of the glenohumeral joint.
AC dislocation is particularly common in collision sports such as ice hockey, football, rugby and aussie rules, and is also a problem for those who participate in swimming, horseback riding, mountain biking, biking and snow skiing. The most common mechanism of injury is a fall on the tip of the shoulder or FOOSH (falls on outstretched hand).
AC dislocations are also graded from I to VI. Grading is based upon the degree of separation of the acromion from the clavicle with weight applied to the arm. Grade I is a tear of the AC ligament. It has the normal separation of <4mm. Grade II is a complete dislocation of AC ligament with partial disruption of coracoclavicular ligament. The AC gap is >5mm. Grades I and II never require surgery and heal by themselves, though physical therapy may be required. Grade III is complete disruption of AC and CC ligaments. On plain film the inferior aspect of the clavicle will be above the superior aspect of the acromion. This can also be assessed with an MRI scan, which will also demonstrate disruption of the coracoclavicular ligaments (the degree depending on the severity of AC joint disruption) as well as tearing of the joint capsule. The joint will be very tender and swollen on examination. Grade III separations most often do not require surgery and shoulder function should return to normal after 1620 weeks. However, there will be some physical deformity of the shoulder with a noticeable bump resulting from the dislocation of the clavicle. Grades IV-VI are complications on a 'standard' dislocation involving a displacement of the clavicle, and will almost always require surgery.