Spontaneous Dissociation of Anatomic Medullary Locking A Plus (AML A Plus) Femoral Component at the Head-Neck Interface

INTRODUCTION: Innovations in the design of total hip arthroplasty components have been developed to address certain limitations with the use of standard monoblock prosthesis. With increasing use and long-term follow up, certain complications particularly related to fretting, corrosion and fatigue have been recognized. CASE REPORT: A 31 year old active male patient presented with spontaneous dissociation of the Anatomic Medullary Locking A Plus (AML A Plus) Femoral Component at head and neck interface 10 years after surgery. At revision surgery, wear of the acetabular liner and head and neck taper was noted. Definitive treatment required complete revision of the femoral component and change of acetabular liner. CONCLUSION: While modularity allows change of worn out components, this case highlights the importance of various factors in avoiding this complication and the need for surgeon to be prepared to use ‘taper sleeves’ or revise the components if taper exchange fails particularly in cases with dissociation of head-neck interface which is usually associated with taper damage.