Advancement and Separation of Apex Hole Eliminators with Cementless Duraloc 100 Cups

Background: From 1992 to 1996, we performed 541 cementless total hip arthroplasties using a Duraloc 100 acetabular component with an apex hole eliminator that did not have a positive stop design. During routine follow-up radiographic evaluation, we noted several hips with advanced or separated hole eliminators. This study presents the clinical consequences of this occurrence and its relationship to polyethylene wear and osteolysis.

Methods: A total of 541 hips (358 with a minimum duration of follow-up of five years) were evaluated clinically with use of the method of Merle D’Aubigné and Postel. Anteroposterior pelvic and iliac oblique radiographs were used to evaluate polyethylene wear, osteolysis, hole eliminator position, and component stability.

Results: Nineteen hips that had been followed for an average of eighty-nine months showed advancement or complete separation of the hole eliminator on radiographic evaluation. In most hips, advancement of the hole eliminator was visible on only the iliac oblique radiograph. In all but one hip with separation of the hole eliminator, complete plug separation was detectable on both the iliac oblique and anteroposterior pelvic radiographs. No association was found between polyethylene wear and either advancement or separation of the hole eliminator. No osteolysis was visible radiographically in the hips with hole eliminator advancement, but osteolysis was always visible in the hips that had complete separation of the hole eliminator.

Conclusions: The hole eliminator has been redesigned since November 1995 to prevent possible advancement. However, patients with earlier designs should be followed carefully because advancement or separation can be expected in about 5% of the patients who have been followed for a minimum of five years. Despite this complication, which is seen radiographically, all patients were satisfied with the function of the hip. We do not recommend surgery solely to remove or replace the hole eliminator.

Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.