Acetabular revision using an anti-protrusion cage in patients with periprosthetic acetabular bone loss / 中华骨科杂志

ABSTRACT

Objective To investigate the risk factors related to the survival time of anti-protrusion cage in acetabular revision.Methods Data of 40 patients who had received acetabular revision using antiprotrusion cages between January 2002 and June 2010 were retrospectively analyzed.There were 16 males and 24 females,aged from 22 to 77 years (average,60.3 years).All patients were followed up for 12 to 82 months (average,39.2 months).According to the AAOS classification,there were 29 cases of type C and 11 cases of type D； while according to the Paprosky classification,there were 29 cases of type ⅢA and 11 cases of type Ⅲ B.The multiple regression analysis was utilized to investigate the relationships between different factors and anti-protrusion cage failure.The corresponding factors included gender,age,bone loss classification,superior or lateral migration of acetabular center of rotation,abduction angle,fixation manners (simple flange fixation or flange fixation plus transacetabular screw fixation),bone grafting techniques and cup type.Results At final follow-up,the average Harris score was 74.5±15.4.Two patients received rerevision due to prosthetic loosening.Obvious radiological loosening of prosthesis combined with pain was found in 2 cases.The statistical analysis indicated that superior migration of acetabular center of rotation,abduction angle and fixation manners were correlated with cup failure,especially when the superior migration was more than 8.5 mm or the abduction angle was larger than 53.5°.Flange fixation plus transacetabular screw fixation could reduce risk of cup failure.Conclusion There is a higher cup failure risk in acetabular revision using an anti-protrusion cage for patients with serious bone defect.However,implanting cup at the level of the true acetabulum as far as possible,decreasing abduction angle properly and using flange fixation plus transacetabular screw fixation can reduce cup failure risk.