To analyze the treatment results of late instability and dislocation of the hip following total hip arthroplasty. The study refers to 16 patients from 42 to 71 years old when had primary THA. The mean time of late dislocation was 9,5 years and the revision mean time was 11 years following THA. In most patients extensive polyethylene wear was documented, in 12 patients the cup or the polyethylene insert on a stable metal implant was revised and in 4 patients new polytethylene cemented insert was placed in a stable metal implant. In all cases exchange of the femoral component metal head took place. During follow up and re-evaluation 2–7 years after the revision there were 13 patients (81.25 %) with a stable THA and good function. Instability remained in three patients, which in 2 was resolved with re-revision of the cup whereas in the third (over aged) a special abduction brace was applied. Late hip dislocation 5 or more years after THA occurs mainly due to extensive polyethylene wear and in contrast with early dislocation requires more often surgical intervention. The main cause of late hip dislocation was the extensive polyethylene wear, which in three cases was associated with prosthesis mal-orientation at primary implantation and in lots of cases with age-related neuromuscular deficit. The treatment of late instability with repetitive dislocations requires surgical intervention. The revision might need exchange of cup or polyethylene insert on a stable metal implant or new polytethylene cemented insert on a stable metal implant.
