Acromioclavicular Joint Repair Treatment in India. The acromioclavicular (AC) joint is the meeting point of the acromion and clavicle bones in the shoulder area, often indicated with a visible bump in the area. AC joint injuries often occur as a result of a fall or other trauma, which may cause the acromion to move or separate from the clavicle, or cause the ligaments to be stretched or torn.