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.