Pinnacle Ultamet metal-on-metal total hip arthroplasty survivorship: average 10-year follow-up

Abstract

Background: It is unclear whether a connection exists between femoral head size, offset, neck length, and cup abduction angles, and rate of revision in metal-on-metal (MoM) total hip arthroplasty (THA) implant systems. Methods: A retrospective review of MoM THA completed by a single surgeon with a single implant between 2003 and 2008 was conducted. Patient demographics, implant data, radiographs, and revision details were collected at follow-up. Incidence rates for revision and osteolysis were calculated in regard to the femoral head size, stem offset, neck length, and cup abduction angles. Results: Six hundred and ninety two THAs were identified, with 79% of patients returning for a median follow-up of 10.3 years (interquartile range ¼ 6.0-12.3). The median time to revision was 7.5 years (interquartile range ¼ 5.3-9.9) among 27 total revision surgeries. The overall incidence rate of revision was 5.4 revisions per 1000 person-years, 3.0 revisions per 1000 person-years for adverse local tissue reaction. Hips with a cup abduction angle of 40 had revisions at nearly twice the rate of those with an angle of 41-50 (incidence rate ratio ¼ 1.98, 95% confidence interval: 0.92, 4.29). Hips with a 9 mm neck length had an increased rate of revision (incidence rate ratio ¼ 5.94, 95% confidence interval: 1.33, 26.55) relative to those with a neck length of 0 mm. Rates of osteolysis were similar between implants of different head sizes, neck lengths and cup abduction angles. Conclusions: MoM implant systems with longer necks and smaller cup abduction angles may lead to increased need for revision. Results from this study suggest a need for closer long-term follow-up of MoM THA systems.

Minimum 10-Year Results of Modular Metal-On-Metal Total Hip Arthroplasty

“…In a large cohort studies, Langton et al [ 15 ] over 9 years, Kindsfater et al [ 16 ] over 9 years, and Pearce et al [ 17 ] over 10 years have identified survival rates of 84%, 94.4%, and 83.4%, respectively. Furthermore, LaHaise et al have suggested that the survivorship of MOM hips may be relatively high (5.4 revisions per 1000 person-years) [ 18 ]. Several small but long-term single-center cohort studies examining the 36-mm MOM Pinnacle THA system have confirmed an 83% survival rate after 15 years [ 7 ].…”