R3 Cup Does Not Have a High Failure Rate in Conventional Bearings: A Minimum of 5-Year Follow-Up

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

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.

Excellent mid-term outcomes with a hemispheric titanium porous-coated acetabular component for total hip arthroplasty: 7-10 year follow-up

INTRODUCTION

Third-generation hemispheric, titanium porous-coated (HTPC) acetabular cups have been shown to achieve good biologic fixation through enhanced porous ingrowth surfaces. They also allow for a wide range of bearing options, including polyethylene, dual-mobility, and ceramic liners. The purpose of the study is to review the mid-term clinical outcomes an HTPC acetabular cup with a minimum of 7-year follow-up.

METHODS

A retrospective, observational study was conducted on all consecutive patients who underwent total hip arthroplasty (THA) with an HTCP acetabular cup at an urban, tertiary referral centre. Descriptive statistics were used describe baseline patient characteristics. Outcomes collected included postoperative complications, survival free of reoperations, and presence of osteolysis at latest imaging follow-up. Implant survival was analysed using the Kaplan-Meier method.

RESULTS

118 cases (114 primary, 4 revision) underwent THA with the HTCP acetabular cup at an average follow-up of 8.16 ± 0.85 years (range 7.02-10.28 years). Mean patient age at the time of surgery was 61.29 ± 12.04 years. All cases utilised a high-molecular-weight polyethylene (HMWPE) liner. None of the acetabular cups showed loosening or migration at the latest follow-up. There were 2 revisions in our study, 1 for abductor mechanism disruption and 1 due to surgical site infection where the acetabular cup was revised. Kaplan-Meier survivorship analysis for all-cause revision at 7 and 10-year follow-up showed a survival rate of 99.1% (95% confidence interval, 94.1-99.9%). Survivorship analysis for aseptic acetabular revision at 10-year follow-up showed a survival rate of 100%.

CONCLUSIONS

At long-term follow-up, no radiologic and minimal clinical complications were identified in this series. The HTPC acetabular cup system, used in conjunction with a HMWPE liner, demonstrates excellent outcomes and survivorship when compared to earlier mid-term studies published in the literature.

The early- to medium-term results of a hemispherical, porous coated acetabular shell with multiple different bearing combinations are excellent with the exception of metal-on-metal

PURPOSE

This study prospectively reports survivorship and radiographic and clinical outcomes following primary elective total hip arthroplasty (THA) using a novel single hemispherical, porous-coated acetabular cup with five different bearing combinations and a minimum of five year follow-up.

METHODS

Continuing post-market release monitoring of this cup, we prospectively enrolled 108 patients (121 THA) between 2009 and 2015. We followed this cohort by examining survivorship, in addition to clinical and radiological outcomes for metal-on-metal (MoM) compared with non-MoM bearing combinations (ceramic-on-ceramic, oxinium-on-polyethylene, ceramic-on-metal, and metal-on-polyethylene).

RESULTS

All 108 (121 hips) patients were followed up. Average age at time of surgery was 45.1 years (range 19 to 71 years) of which 42.1% were males. A total of seven (5.8%) cups were revised, all of which were MoM. No osteolysis was observed in any of the patients at the latest visit with a mean follow-up of 9.1 ± 1.7 years (range 4.4-10.7 years). With MoM excluded, survivorship of the cup at five  years is 97.8%. Survivorship for MoM implants was 90.0%. Validated hip scores showed significant improvements for all bearing types and no significant difference between groups at latest follow-up (p = 0.614). There was no cup migration with any bearing surface.

CONCLUSION

This cup showed excellent survivorship at five year follow-up, except for patients receiving a MoM articulation. While there were concerns over the early survivorship of this cup, our cohort and joint registry data confirm excellent outcomes.

Acetabular Liner Dissociation: A Comparative Study of Two Contemporary Uncemented Acetabular Components

BACKGROUND

There are a number of reports of polyethylene liner dissociation of third-generation modular acetabular components. This study compares our experience with 2 contemporary systems to determine whether this is an implant- or class-specific problem.

METHODS

This is a single-center retrospective study of 961 primary total hip arthroplasties using 2 third-generation modular cementless acetabular shells: Pinnacle (535) and R3 (426) with a polyethylene liner. Details of all revisions were obtained from local databases and the New Zealand Joint Registry. Kaplan-Meier survival curves were calculated for all-cause revision, acetabular reoperation (including liner exchange), and liner dissociation.

RESULTS

There were 17 revisions in group 1 (Pinnacle; DePuy Synthes): 17 for recurrent dislocation, 6 for liner dissociations (1.12%), 3 for femoral loosening, and one for deep infection. In group 2 (R3; Smith and Nephew), there were 4 revision procedures: one for infection, 2 for dislocation, and one femoral revision for periprosthetic fracture. There were significantly higher proportions revised in group 1 for all-cause revision, acetabular reoperation, and dissociation (P = .024 to 0.038). The 7-year survival for all-cause revision was 96.1% for Pinnacle and 99.0% for R3 (P = .022), and that in the acetabular reoperation group was 96.9% for Pinnacle and 99.3% for R3 (P = .035).

CONCLUSIONS

There was a higher revision rate for the Pinnacle acetabular component than for the R3 at 7 years. This was mainly due to polyethylene liner dissociation that can occur early or late. It appears to be a problem specific to the Pinnacle cup design rather than a feature of similar third-generation acetabular components.

Midterm Results of a Contemporary, Porous-Coated Acetabular System in Patients Undergoing Primary Total Hip Replacement for Degenerative Hip Disease: A Prospective, Multicenter Study

BACKGROUND

A contemporary, porous-coated acetabular implant designed for uncemented insertion was introduced in Europe and Australia in 2007. A similar previous acetabular system was found in several studies at 10 to 15-year follow-up to demonstrate accelerated polyethylene wear, osteolysis, and early failure. The current study was conducted to determine the midterm safety and effectiveness of this contemporary acetabular system using highly crosslinked polyethylene and ceramic liners at 5-year follow-up.

METHODS

A prospective, nonrandomized study was conducted at 8 sites in Canada and the United States. All 148 study participants received a contemporary acetabular shell with proprietary porous coating. The primary outcome was the requirement for revision surgery at 5 years postoperatively. Secondary outcomes included a survival analysis, patient-reported outcome measures, radiographic failure, and postoperative adverse events.

RESULTS

At 5-year follow-up there was 1 cup revised for deep infection. No cups were revised for loosening and none were found to be radiographically loose. The overall survival rate with reoperation for any reason was 97.1%. The success rate was 96.8% for polyethylene and 100% for ceramic with no difference in the success rate between either bearing surface (P = 1.0). The mean patient-reported outcome measures all improved significantly between preoperative and 5-year postoperative scores (P < .001).

CONCLUSION

Results from this 5-year, multicenter, prospective study indicate excellent survivorship for this acetabular system when used with crosslinked polyethylene or ceramic bearing surfaces.