Instabilities and associated fractures of the acromioclavicular joint

Background. Increasing scientific interest in acute acromioclavicular joint (ACJ) instabilities and ACJ-associated fractures has been observed in the past few years. This may be due to the lack of data in the literature regarding specific treatment indications, unsatisfying results of open techniques, and the development of new minimally invasive surgical procedures. Treatment selection and results. Acute ACJ instabilities are still graded according to their vertical component of instability. However, dynamic horizontal instability should also be taken into account. Even in lateral clavicle fractures, it is important to determine vertical instability due to coracoclavicular ligament injury, which is associated with higher risk of pseudarthrosis when treated conservatively. Surgical treatment of high-grade ACJ instabilities and dislocated lateral clavicle fractures has traditionally been a domain of open surgery. Today, available arthroscopic and arthroscopically-assisted techniques offer the potential of less soft-tissue preparation, a smaller risk of infection and, under cosmetic aspects, higher patient acceptance. The medium-term results of these minimally invasive techniques can compete with those of open techniques. Long-term results are still lacking.