The acromioclavicular joint: normal variation and the diagnosis of dislocation.

Acromioclavicular separation is a common traumatic injury. Diagnosis rests on clinical and radiographic findings. However, normal variation in the alignment of the acromioclavicular joint may make the roentgen diagnosis more difficult. We stress the variations of normal alignment at the acromioclavicular joint and offer suggestions for avoiding pitfalls in this clinical situation.