Anatomy in multidirectional instability

Multidirectional instability (MDI) is a condition in which dislocation occurs in more than one direction, with little or no causal trauma. The main symptoms reported are shoulder pain, instability and disability. The diagnosis is based primarily on the clinical history and imaging of MRI which allows for the best anatomical assessment including soft tissue. When MDI occurs, it means that one or more of the shoulder containment mechanisms is failing. Over the years, several anatomical conditions and variables that predispose to this condition have been considered and will be described in detail in this chapter, such as capsular redundancy, incompetence of the glenohumeral ligaments, laxity of the rotator interval, increased glenoid retroversion, flatness of the articular surface or glenoid hypoplasia.