Fractures of the collar bone are common injuries that can sometimes be associated with dislocation of the ACJ (Acromioclavicular joint). Fractures in children and those that are in the middle with little shortening or displacement will heal by themselves. If the fracture is at the outer end or is very shortened /displaced or in many pieces, it might need to be plated to restore length and function in addition to being pleasing cosmetically. Special plates are available to fix the collar bone very well.
The ACJ can dislocate after injury such as falls, cycling /motorcycling accidents and there are 6 grades of injury. Grade 1 and some grade 2 injuries can be treated with a sling, rest and generally do not cause long term problems. Very displaced grade 3 and higher injury require surgery to restore the anatomy to normal, improve shoulder function and gives a very pleasing cosmetic result. I prefer the Hook plate as it is reliable and in late presentations additional reconstruction of the CC ligament may be required.