Cementless acetabular cups in total hip arthroplasty: A comparison of two generations at mid-term review

摘要

Introduction udEarly versions of cementless acetabular cups in total hip arthroplasty (THA) led to peri-acetabular osteolysis from back-side wear of the polyethylene liner. This unforeseen problem contradicted benefits of using cementless components in younger patients. Subsequent generations of components were designed to reduce this problem and its negative effect on the survival of the THA.udPatients/Materials and MethodsudWe compared the incidence of radiographic changes in a cohort of second-generation cementless acetabular components (EPF cups, Smith&Nephew), with a matched cohort of an earlier design (Harris-Galante) at mid-term (6-11 years). Cohorts were matched by age, gender, co-morbidities, smoking status and time from primary surgery. Presence of radiolucencies or osteolysis was recorded by zone around acetabular components on AP pelvis and iliac oblique lateral views, and the proportion of changes were statistically compared (Chi square test).udResultsudThere were 20 patients in each cohort, treated by five resident orthopaedic surgeons in a district general hospital, with mean age 75 years (60 to 82), 40 % female, Exeter femoral stems in 37 patients (CPS Plus, Smith&Nephew, in 3 THA). There was a statistically significant greater proportion of changes seen behind the Harris-Galante cup in De Lee and Charnley zones 2, 4 and 5 than the EPF cup (zone 2 =75% compared with 25%; zone 4 =45% compared with 10%; zone 5 =60% compared with 10%).udDiscussionudIn this small, matched cohort study, we have shown that, in our district general hospital, the newer second-generation cementless acetabular components lead to less peri-acetabular osteolysis than their first generation counterparts at mid-term radiographic review.udConclusion udThe incidence and progression of osteolysis have a detrimental effect on survival of THA. These results have implications for follow-up of THA patients, indicating that prosthesis type should inform the timing of a review for a clinically effective surveillance service to benefit patients.