Mid-term clinical outcomes of the uncemented Robert Mathys pressfit cup

Abstract

Background: The use of uncemented cups during total hip arthroplasty (THA) has gained popularity in recent years. The Robert Mathys (RM) pressfit cup, an uncemented monoblock implant is expected to preserve bone density due to its composition and external surface, while reducing backside wear with its monoblock construction. These factors should lead to a high survival rate of the implant.

Aim: To evaluate the mid-term survival and functional outcome of the RM Pressfit cup in a large study population.

Methods: Between 2011 and 2020, we included 1324 patients receiving a primary THA using the RM pressfit cup. Final clinical follow-up was performed at 2 years postoperatively with the Dutch arthroplasty register used to assess implant status thereafter. Revision for acetabular failure and reason for revision were reported to evaluate implant survival, while the hip disability and osteoarthritis outcome score (HOOS) scores were used to assess functional outcome.

Results: The mean age at surgery was 64.9 years. The mean follow-up was 4.6 years. Of the 1324 THAs performed, 13 needed cup revisions within 5 years after index THA: 5 due to aseptic loosening, 6 due to infection, 2 due to dislocation and 2 due to other causes. This resulted in a 5-year cup survival of 98.8% (95%CI: 98.1-99.5). Nine of the cup revisions occurred within the first year after index THA. HOOS scores increased significantly in all domains during the first year and levelled out during the second year.

Conclusion: In the present study, the RM pressfit cup demonstrated excellent clinical outcomes at mid-term follow-up; however, future studies are needed to assess the long-term outcomes of this acetabular implant.

Keywords: Aseptic loosening; Cup revision; Hip osteoarthritis; Pressfit; Total hip arthroplasty; Uncemented RM pressfit cup.

Figure 1

Kaplan-Meier curve visualizing the 5-year survival of the Robert Mathys pressfit cup. A: Revision for acetabular failure with the numbers at risk each year; B: All-cause revision, with the numbers at risk each year.

Figure 2

Line graph illustrating the changes in hip disability and osteoarthritis outcome score per domain at each follow-up (with 95%CI). ADL: Activities in daily living; HOOS: Hip disability and osteoarthritis outcome score.