Introduction : The Kerboull Acetabular Reinforcement Device has been used

since 1974 in acetabular reconstruction. Dual Mobility System has been used in

clinical practice for Total Hip Arthroplasty since 1976. The construct is a cemented

dual mobility socket in acetabular reinforcement device which was widely used in

France. Unfortunately, this concept was hard to introduce in North American

practices.

We report our experience with 16 hips treated using this construct dual mobility

socket cemented in Kerboull Acetabular Reinforcement device in some revision hip

arthroplasty.

Methods : This is a retrospective monocentric study with 16 dual mobility

components cemented in Kerboull renforcement device implanted in 15 selected

patients between 2011 and 2018 with a 1 year minimum follow-up. This technique

was used in 10 cases associated with aseptic acetabular loosening, 3 cases after

prothesis joint infection, 2 cases associated with rapidly destructive coxarthrosis

and 1 case after failed revision. There was 4 women and 11 men, and the mean age

at the time of the surgery was 69 years (range between 40 and 88 years). The

average follow up was 42 months (range between 12 and 72 months). Paprosky

classification was used for the acetabular bone defect: 3 hip type 2A type, 3 cases

type 2B, 4 cases type 2C, 4 cases type 3A and 2 cases 3B type.

Postel Mearle D’Aubigné classification was used to evaluate the functional ability.

Bone grafting, autologus and frozen bone graft was used in all cases.

Results : The Kerboull Acetabular Reinforcement device restored the acetabulum

continuity and the dual mobility component restored hip stability. There was no

dislocation for all the patients. At the last follow up, we identified no patients with

acetabular component loosening or osteolysis. Unfortunately, one patient with

pelvic discontinuity had acetabular reinforcement device displacement and a

secondary revision was necessary The acetabular implant showed satisfying

osteointegration and the bone grafting incorporated.

Conclusion : The results of our study support the use of KARD with cemented

dual mobility socket implants for revision hip arthroplasty and it is a good option in

well indicated cases. This design was very efficient in restoring and maintaining

hip stability and continuity. It is a keen choice in challenging situations of unstable

and bone loose revision hip arthroplasties. However, longer follow up is required.

Objectives: To assess outcomes of a cemented dual mobility acetabular component in patients at increased risk of dislocation following primary and revision total hip arthroplasty.

Methods: Outcomes following implantation of a cemented dual mobility shell at a single UK centre were assessed retrospectively using clinical and radiological data. Inclusion criteria were primary and revision procedures with minimum 1 year follow up. Dual mobility implants were utilised selectively for high risk cases at the surgeons’ discretion. Patients were identified using data from the UK National Joint Registry (NJR).

Results: Between August 2014 and May 2018 104 cemented ADES (Zimmer, Warsaw, Indiana, USA) dual mobility shells were implanted. There were 60 primary and 44 revision procedures. 23 revisions were performed to address hip instability.

The mean length of follow up was 3.22 years (range 1.67-4.92) and the mean patient age at the time of surgery was 72 years (range 34-89).

20 dual mobility shells were used for complex primary THA, 16 for fractured neck of femur, and 15 in patients with a pre-existing neuromuscular disorder.  There were 4 cases of postoperative dislocation; 3 of which occurred in revision cases. 2 patients required reoperation for instability: at 1 and 3 months. No case was complicated by infection or intraprosthetic dislocation.

All implants present at 1 year follow up had satisfactory radiographic appearances.

Conclusions: These results demonstrate a low complication rate when a cemented dual mobility acetabular component is implanted in patients at high risk of dislocation. Further data is required to assess outcomes in the longer term.

INTRODUCTION:   Modular dual mobility systems have been implanted increasingly over the last decade.  To date, these systems have primarily utilized a CoCrMo liner locked into a titanium alloy shell.  Cases with corrosion at the liner taper junction and adverse tissue reactions to corresponding Co, Cr, and Ni ions/debris have been reported.  Use of a more inert material, such as Zr2.5Nb, could reduce taper-related complications.  The goal of this study was to evaluate polyethylene wear of a new modular dual mobility system with a diffusion-hardened oxidized Zr2.5Nb acetabular bearing.  In order to replicate a worst-case scenario, motion was isolated to the outer articulation of the device.  An established, clinically successful, non-modular dual mobility system was tested for comparative purposes. 

METHODS:  Two dual mobility systems were tested.  An extruded square feature was incorporated into each insert design and replaced the hemispherical cavity that normally mates with a femoral head.  This feature was designed to mate with a Ti6Al4V fixture with corresponding geometry and, thereby, eliminated the inner articulation/femoral head.  System 1 (R3DM)  incorporated a modular acetabular system consisting of an R3™ shell and 54 mm ID, diffusion-hardened, oxidized Zr2.5Nb liner paired with a 10 Mrad irradiated, remelted, UHMWPE (XLPE) insert.  System 2 (PCDM) consisted of a 67 mm stainless steel POLARCUP™ shell (61 mm ID) paired with a XLPE insert.  The acetabular sizes tested represent the largest for each system.

RESULTS and DISCUSSION:  Mean wear rate of R3DM inserts was ≈58% lower than that of PCDM inserts (p < 0.05) and within the range of 36 mm ID and 44 mm ID XLPE liners tested under similar conditions.  While isolation of all motion at the outer bearing is unlikely to occur clinically, it is believed to be a worst-case scenario as recent in-vivo studies indicate volumetric wear of highly crosslinked UHMWPE liners may increase with head diameter.  Reduced wear for R3DM as compared to PCDM is attributed to the use of an improved acetabular bearing material (DHOxZr) and reduced articulation size (54 mm).  As previous in-vitro tests indicate wear of XLPE is influenced more greatly by counterface material than diameter, bearing material is hypothesized to play a larger role.  Nonetheless, further testing is needed to definitively determine relative contributions of acetabular bearing material and articulating diameter to the difference in wear observed.