What is the survivorship of fully coated femoral components in revision hip arthroplasty?

BACKGROUND: Femoral revision using fully coated femoral components offers distinct advantages in patients with notable bone loss. With the increasing concerns being raised about the problems of stem modularity, the results and complications of revision arthroplasty using devices with limited modularity are important.

QUESTIONS/PURPOSES: We therefore asked: (1) What is the frequency of infection, aseptic loosening, and reoperations after use of these components? (2) What is the frequency of intraoperative fracture of the femur when using these components and are there any identifiable factors related to these fractures? (3) What is the 10-year survivorship of these components, and are there any identifiable factors related to survival and rerevision?

METHODS: We retrospectively reviewed prospectively obtained data on 96 patients undergoing 104 revisions with fully coated components of two different manufacturers; six patients had died (6%) and six were lost to followup (6%) before 2 years. Data on intraoperative fracture, aseptic loosening, and reoperation were analyzed. Ninety-two hips, with a minimum followup of 2 years (mean, 8 years; range, 2-16 years), were evaluated for radiographic evidence of loosening. Intraoperative fracture frequency and Kaplan-Meier survivorship was calculated to 10 years for the entire cohort of 104 hips. Demographic, radiographic, and operative factors associated with implant survival and intraoperative fracture were analyzed using chi-square and Wilcoxon tests.

RESULTS: There were three infections, nine hips (10%) had femoral component loosening (six rerevised), and there were seven other reoperations. Intraoperative complications in 17 hips (17%; 11 diaphyseal fractures, four perforations, two proximal fractures) were treated with allograft strut and cable fixation in 14 hips. Intraoperative femoral complication was more likely with the use of a curved stem [17 of 76, 22% curved; 0 of 28 straight stems (p=0.005)]. With failure defined as femoral component revision for aseptic loosening or radiographic evidence of loosening, implant survival was 88% at 10 years. Those femurs with Paprosky Grades 3B and 4 defects had a higher risk of loosening (3 of 10 for Grades 3B and 4 versus 6 of 94 hips [6%] for Grades 1, 2, 3A; p=0.03).

CONCLUSIONS: As concerns about stems with more modularity become more prominent, we find the durability of the approach using fully coated femoral components reassuring, but we will continue to follow these patients in the longer term.

LEVEL OF EVIDENCE: Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.