Neer and Foster first described the diagnosis and management of MDI, based on their study of patients with inferior subluxation or dislocation and associated anteroposterior subluxation or dislocation. They identified three types of MDI: anteroinferior dislocation and posterior subluxation, posteroinferior dislocation, and anterior subluxation, and dislocation in all three directions. Neer and Foster distinguished MDI from the more commonly recognized unidirectional anteroposterior instability, emphasizing the often-subtle presentation of MDI and the pitfalls of treating it with a traditional unidirectional repair. They proposed using an inferior capsular shift, and this procedure has had good intermediate-term results.
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