Multidirectional Instability: Natural History and Evaluation

BACKGROUND Multidirectional instability (MDI) represents a great challenge to the orthopedic surgeon. When treating these patients we must be aware that instability refers to a symptomatic situation, thus multidirectional instability is defined as symptomatic involuntary instability in two or more directions, and should be clearly differentiated from asymptomatic hyperlaxity. It may be associated with hyperlaxity, either congenital or acquired following repetitive stress, but also may be present without hyperlaxity, which is rare. METHODS We searched in the online data bases and reviewed the relevant published literature available. RESULTS Many differences can be seen in the current literature when identifying these patients, unclear definitions and criteria to be included in this patient group are common. CONCLUSION Understanding the complex shoulder biomechanics as well as being aware of the typical clinical features and the key examination signs, which we review in this article, is of paramount importance in order to identify and classify these patients, allowing the best treatment option to be offered to each patient.