"Instability after THA continues to complicate approximately 2% to 5% of primary surgeries and 5% to 10% of revision surgeries. There seems to be a higher risk of dislocation after primary THA performed in women, the elderly, and patients with previous hip surgery or hip fracture as an underlying diagnosis."
"Conditions that imply noncompliance with hip dislocation precautions or neuromuscular dysfunction also increase the risk of postoperative instability."
"Several surgical factors seem to be associated with higher dislocation rates: posterolateral approach, malorientation of the components, decreased head-to-neck ratio, proximal placement of the acetabular component, decreased femoral offset, and abductor insufficiency secondary to trochanteric migration or abductor avulsion. Patients with greater range of motion are at an increased risk of late dislocation. The likelihood of instability being recurrent seems to be influenced by the timing of the first episode, a history of prior surgery, and whether the implants are oriented optimally.
"An individual surgeon's dislocation rate appears to be inversely proportional to his or her experience (at least below a certain threshold of experience); this is probably due to the better understanding and management of the complex interplay of factors that govern hip stability that is gained with repetition of the procedure. "