Introduction: Many publications have already shown the great interest of dual-mobility concept which significantly reduces the rate of prosthetic dislocation and thus find its place for patients at high risk of post operative instability. The aim of our study is to evaluate the prevalence of prosthetic instability in revision total hip arthroplasty using a dualmobility cup.
Materials and Methods: Our multicentric series consists of 163 revision total hip arthroplasties performed between may 1999 and may 2004. The mean age at revision was 70 years and the mean follow-up period was 56 months.
The primary etiology necessitating revision is aseptic loosening.
According to the SOFCOT classification, the acetabular deficiency was grade IV 9 times, grade III 47 times, grade I or II 107 times.
All the implanted acetabular components are SERF dual-mobility implants. This system consists of a metal back which can be HA-coated and Press Fit or cemented in a Kerboull cross or in a Novae Arm. The mobile-bearing insert which allows a dual articulation between the head and the metal back is of polyethylene.
We implanted 119 HA-coated press-fit cups and cemented 44 dual-mobility cups in a support ring or in a Kerboull cross.
Results: The mean Merle d’Aubigné and Postel score is 14,1 at the last follow-up and 4,2 in the preoperative period.
We reported 8 complications: 6 early dislocations and 2 acetabular revisions for secondary mobilisation of the cup.
Discussion: According to Huten’s 1996 SOFCOT teaching conference, this rate ranges between 2 and 5% and we have already published a series of 106 dual-mobility with no dislocation at a 10 year follow-up period.
With 4% dislocations at a mean follow-up of 56 months, the dual-mobility cup seems to provide high stability in revision hip surgery when other factors such as muscular deficiency, extended synovectomies, difficult implant placement, encourage an uncertain postoperative prosthetic stability.
These results have to be compared to those of other systems such as constrained acetabular cups or tripolar cups.
Conclusion: This is why dual-mobility remains an efficient and reliable choice to avoid prosthetic dislocation in revision surgery. Moreover, we encourage the use of dual-mobility cup in any high risk situation in terms of post-operative instability such as for old or neurological patients.
