SHORT TERM RESULTS OF THE DUROM ACETABULAR COMPONENT – IS IT SUSCEPTIBLE TO “SPIN OUT” IN OUR EXPERIENCE?

Abstract

Introduction: The Durom hip acetabular component is a large diameter metal on metal (MoM) implant that has recently been the subject of much controversy. Dr. Lawrence Dorr, reported in a letter in April 2008 to the American Association of Hip and Knee Surgeons a worryingly high number of early revisions, as many as 8%, within the first 2 years as a result of a loose acetabular component. Following a Zimmer investigation an early revision rate of 5.7% in the US, but not in Europe, was revealed and this has resulted in the withdrawal of the implant from the market in the US and justifiable concern with regards to its usage resulting in decreased implantation within the UK. Surgical technique in the US has been sited as the main reason for failure as a result of low volume centres not performing crucial steps in the technique which include, but are not limited to, line-to-line reaming, use of trials in every case, proper cup position for this device, appropriate impaction techniques and no repositioning. We present the short term results and our experience of the Durom Acetabular component in our centre in the UK.

Method: We reviewed all patients that had a Durom Acetabular component implanted since its usage began in our unit in 2003. No patients were excluded and the end point being revision surgery of the Durom acetabular component. In addition we analysed the plain radiographs of a random selection of 50 patients to assess component integration.

Results: 260 patients had undergone primary hip surgery with the implantation of the Durom Acetabular component. 108 as part of a hip resurfacing and 152 as a large bearing MoM THR. Their follow up ranged from 1 to 7 years. 1 had undergone revision for thigh pain with aseptic failure of the acetabular component, 1 for ALVAL, 3 had undergone revison for infection and 1 for peri-prosthetic fracture. Analysis of the radiographs revealed a number of acetabulae with a lucent line visible around the implant. None of the implants had migrated from their original position at implantation.

Conclusions: At present their appears to be no evidence in our unit that the Durom Acetabular component has a higher than expected rate of early revision. However, a number of patients do appear to have lucency around the component on radiographs raising the possibility of questionable bony integration and on growth. Reports from the United States have suggested that the cup will “spin out” easily at revision showing no signs of bony integration. This may result in an increased revision rate in the future and we suggest that all patients that have a Durom acetabular component in situ be followed up with yearly clinical assesment and radiographs to assess the longevity of this component.