Progressive radiolucent lines following the implantation of the cemented Rimfit acetabular component in total hip arthroplasty using the rimcutter technique

Aims

The highly cross-linked polyethylene Exeter RimFit flanged cemented acetabular component was introduced in the United Kingdom in 2010. This study aimed to examine the rates of emergence of radiolucent lines observed when the Rimfit acetabular component was implanted at total hip arthroplasty (THA) using two different techniques: firstly, the ‘rimcutter’ technique in which the flange sits on a pre-prepared acetabular rim; and secondly, the ‘trimmed flange’ technique in which the flange is trimmed and the acetabular component is seated inside the rim of the acetabulum.

Patients and Methods

The radiographs of 150 THAs (75 ‘rimcutter’, 75 ‘trimmed flange’) involving this component were evaluated to assess for radiolucencies at the cement/bone interface by three observers.

Results

Rimfit acetabular components implanted using the rimcutter technique had significantly higher rates of radiolucency than those introduced using the ‘trimmed flange’ technique one year post-operatively (one zone: 63/75 (84%) vs 17/75 (23%); two zones 42/75 (56%) vs 0/75 (0%); all three zones 17/75 (23%) vs 0/75 (0%):(all p < 0.001).

Conclusion

On the basis of these findings, we have stopped using the ‘rimcutter’ technique when implanting the Rimfit acetabular component and have reverted to the ‘trimmed flange’ technique.

Take home message: Surgeons should be vigilant of the performance of the Rimfit acetabular component when used alongside the rim cutter device due to an observed higher rate of progressive radiolucencies with this combination of component / technique.