Dual Mobility Sockets Research Articles

Dual mobility: A choice for primary total hip arthroplasty?

Dual-mobility sockets were introduced in the United States in 2010. The smaller inside diameter head offered the potential advantage of lower wear and the larger outside diameter head offered the potential advantage of improved stability. Initially, indications were advocated for patients with increased instability risk. However, with larger diameter metal-on-metal articulations falling out of favor, the indications for dual-mobility components are expanding. The author has used this design in over 400 primary THAs with only one dislocation. One loose cup was revised. Dislocation of the smaller femoral head from the larger polyethylene head remains a theoretical risk with DM designs.

Evora® chromium–cobalt dual mobility socket: Results at a minimum 10 years’ follow-up

The Evora chromium-cobalt alloy dual mobility socket claims to display a large articulation tribology different from that of stainless steel models, limiting the risk of intraprosthetic dislocation and wear. The present study reports a minimum of 10years' follow-up in a multicenter prospective series of 200 sockets previously reported on at 5years. The use of chromium-cobalt in dual mobility sockets provides a low rate of failure at 10years, especially as regards to osteolysis and intraprosthetic dislocation. Two hundred hydroxyapatite-coated molded chromium-cobalt sockets without titanium interface were implanted without cement in 194 patients with a mean age of 70 years (range, 32-91 years). Clinical results were assessed on Postel Merle d'Aubigné and Harris scores, plain radiographs and survival analysis. At a mean 11 years' follow-up (10-13 years), 56 patients had died and 31 were lost to follow-up. Four underwent surgical revision (3 femoral components, and 1 socket for migration at 9 years with complete disappearance of the hydroxyapatite). A total of 109 implants were analyzable in 107 patients with a mean age of 81 years (55-93 years). At follow-up, the mean Harris score was 90 (75-96) and the PMA score 16.3 (14-18). There were no cases of loosening (except for the case reoperated on at 9 years) and no acetabular radiolucency or cysts. There were 2 cases of non-evolutive femoral radiolucency and 10 of femoral granuloma, involving head size > 22 mm (P<0.0001) and a cemented titanium stem (P=0.004) as risk factors. There were no dislocations in the large or small articulation. Ten-year survival was 99% (95% CI: 97.3%-100%) with socket revision as censorship criterion. The absence of dislocation in both small and large articulations confirmed the efficacy of the dual mobility concept and suggested an advantage for chromium-cobalt sockets in reducing the rate of intraprosthetic dislocation and preventing blockage of the large articulation by a better performance in the friction couple. Granulomas were associated with wear in cemented titanium stems and with heads greater than 22 mm in diameter. Ten-year survival was 99% (censorship criterion: revision for socket failure); there was, however, one case of socket loosening with disappearance of the hydroxyapatite, indicating that surveillance should be continued in this cohort.

What Are the Causes for Failures of Primary Hip Arthroplasties in France?

There are no large database cohorts describing the causes for failure of primary THAs in France. Because implants and causes for revision vary between national registers, it is important to obtain data from all countries. We therefore determined (1) the mechanisms of failure of primary THAs, (2) their order of appearance with time, (3) the types of surgical techniques and implant designs used to perform revision THAs, and (4) 90-day complications after revision THA in France. We prospectively collected data on all 2107 first-time revision THAs from 30 tertiary centers from January 1, 2010, to December 31, 2011. A dual-mobility liner had been used in 251 hips. Mean time from primary procedure to revision THA was 11.2 years (range, 1 day to 42 years). Mean age at revision was 70 years (range, 17-104 years). The causes for revision were mechanical loosening (42%), periprosthetic fracture (12%), infection (11%), wear/osteolysis (11%), dislocation (10%), surgical technique error (6%), and implant fracture (3%). The most common type of revision procedure was all-component revision (49%). A dual-mobility liner was used in 1184 hips (62%). The 90-day dislocation rate was less than 4%, and mortality rate was 1.6%. Contrary to other reported data, we found dislocation was not the main cause for failure of primary THAs but was still the more frequent early complication after revision. These findings might be related to the use of dual-mobility sockets in more than 10% of primary THAs and more than 60% of revision THAs.

Is a Cementless Dual Mobility Socket in Primary THA a Reasonable Option?

Dislocation after THA continues to be relatively common. Dual mobility sockets have been associated with low dislocation rates, but it remains unclear whether their use in primary THA would not introduce additional complications. We therefore asked whether a current cementless dual mobility socket (1) reduced the dislocation rate after primary THA, (2) provided a pain-free and mobile hip, and (3) provided durable radiographic fixation of the acetabular component without any unique modes of failure. We retrospectively reviewed 168 patients who underwent primary THA using a dual mobility socket between January 2000 and June 2002. The average age at surgery was 67 years. We assessed the rate of dislocation, hip function, and acetabular fixation on serial radiographs. Of the 168 patients, 119 (71%) had clinical and radiographic evaluation at a minimum of 5 years (mean, 6 years; range, 5-8 years). A long-neck option left the base of the Morse taper uncovered in 53 hips. Four patients underwent revision for dislocation between the femoral head and the mobile insert (intraprosthetic dislocation) at a mean 6 years; all four revisions occurred among the 53 hips with an incompletely covered Morse taper. A current cementless dual mobility socket was associated with a pain-free and mobile hip and durable acetabular fixation without dislocations if the long-neck option was not used. However, intraprosthetic dislocation related to contact at the femoral neck to mobile insert articulation required revision in four hips. Surgeons should be aware of this specific complication. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Severe Metallosis Owing to Intraprosthetic Dislocation in a Failed Dual-Mobility Cup Primary Total Hip Arthroplasty

We report a case of extensive metallosis owing to an intraprosthetic dislocation of a dual-mobility cup after a primary total hip arthroplasty. A 70-year-old man was referred to us from another center with a painful right hip 3 years after the arthroplasty. Initial investigations were suspicious of osteolysis secondary to metallosis with the characteristic “bubble sign” visualized on plain radiographs. At the revision procedure, widespread black staining of soft tissues and bone was noted. The polyethylene liner had dislodged leading to erosion of the metal socket by the prosthetic head. Histopathology examination of periprosthetic tissue confirmed metallosis. To our knowledge, this is the first reported case of severe metallosis owing to a known complication of dual-mobility sockets.

Component Dissociation after Closed Reduction of Dual Mobility Sockets - A Report of Three Cases

Dual mobility sockets have been introduced in recent years to manage cases of potential instability after hip arthroplasty, and their use is increasing in revision surgery. We present 3 cases of intra-prosthetic dissociation between the outer polyethylene liner and the femoral head after closed reduction of prosthetic dislocation.

The use of a cemented dual mobility socket to treat recurrent dislocation.

The treatment of recurrent dislocation after total hip arthroplasty remains challenging. Dual mobility sockets have been associated with a low rate of dislocation but it is not known whether they are useful for treating recurrent dislocation. We therefore asked whether a cemented dual mobility socket would (1) restore hip stability following recurrent dislocation; (2) provide a pain-free and mobile hip; and (3) show durable radiographic fixation. We retrospectively reviewed 51 patients treated with a cemented dual mobility socket for recurrent dislocation after total hip arthroplasty between August 2002 and June 2005. The mean age at the time of the index procedure of was 71.3 years. Of the 51 patients, 47 have had complete clinical and radiographic evaluation data at a mean followup of 51.4 months (range, 25-76.3 months). The cemented dual mobility socket restored complete stability of the hip in 45 of the 47 patients (96%). The mean Merle d'Aubigné hip score was 16 ± 2 at the latest followup. Radiographic analysis revealed no or radiolucent lines less than 1 mm thick located in a single acetabular zone in 43 of 47 hips (91.5%). The cumulative survival rate of the acetabular component at 72 months using revision for dislocation and/or mechanical failure as the end point was 96% ± 4% (95% confidence interval, 90%-100%). A cemented dual mobility socket was able to restore hip stability in 96% of recurrent dislocating hips. However, longer-term followup is needed to ensure that dislocation and loosening rates will not increase.

Survie à dix ans d’une cupule double mobilité non cimentée

Purpose of the study We report a retrospective series of 106 total hip prosthesis with ten years follow-up. The purpose of this study was to analyze survival of cementless dual mobility sockets. Material and methods The series included 90 consecutive patients with 106 first-intention total hip prosthesis, all with cementless dual mobility sockets. All prosthesis (Novae-1 ® socket and Profil-1 ® stem, Serf) were implanted within a 6-month period. The stainless steal socket was coated with alumina and had two short anchorage studs and a superior mooring screw and a polyethylene retentive liner. The stem had a 22.2 mm chromium cobalt head. The main indication for arthroplasty was degenerative joint disease. Mean age at implantation was 56 years (range 23-87). All patients were seen for physical examination and x-rays every two or three years. We noted cup survival at ten years (actuarial method), defining surgical revision for cup replacement due to an aseptic cause as the endpoint. Results Twelve patients died during the 10-year follow-up and one was lost to follow-up. The Postel-Merle d’Aubligné score improved from 7.1 preoperatively to 15.8 at ten years. There were two isolated acetabular loosenings, two intra-prosthetic dislocations due to advanced wear of the polyethylene insert. The overall survival rate of the socket was 94.6% at ten years. There were no episodes of prosthetic instability in this series. Discussion This study demonstrates the good ten-year survival of the dual mobility socket, comparable to that of conventional prostheses. The absence of any case of prosthetic instability in this series confirms the good short-term and long-term stability of the dual mobility socket. Intraprosthetic dislocation, due to loss of the polyethylene retaining ring is the main limitation of this method. The incidence was however low (2% at ten years) and treatment was not a problem. We recommend using the dual-mobility socket as the first-intention implant for patients with a high risk of post-operative instability, but also recommend it for all patients aged over 70 years since instability is the leading cause of surgical revision after this age.

Luxation intra-prothétique dans la cupule à double mobilité de Bousquet: À propos de 7 cas

Purpose of the study The Bousquet system is a dual mobility head-polyethylene polyethylene-metal cup socket. The polyethylene insert retaining the femoral head moves in the noncemented metal cup, increasing both mobility and stability. Material and method Between 1989 and 1997, seven cases of intra-prosthetic dislocation (six patients) were observed. The femoral head escaped from the polyethylene insert due to wear. On the average, this complication occurred ten years after implantation. Risk of dislocation was high in six of the seven hips. All patients had a large sized stem screwed into the femoral neck. There was a characteristic radiological aspect with loss of the concentric head metal cup configuration. The head was applied against the upper wall of the metal cup. Results Surgical replacement was undertaken early in six patients by simply changing the insert without modifying the other stable components. Outcome remained good at three to eight years. One patient underwent late surgery. The insert and the cup were replaced with a classical implant. Functional outcome was good but recurrent dislocation occurred. Discussion At mid-term, intra-prosthetic dislocation of dual mobility sockets appears to be exceptional. Dislocation results from polyethylene wear leading to failure of the insert to retain the prosthetic head. Wear is favored by direct phenomena (direct contact between neck and insert which can occur early if there is a small difference in the head and neck diameters) or indirect phenomena (factors limiting polyethylene metal-cup mobility). Surgical treatment is necessary. If undertaken early, replacement with a modular head and insert can be sufficient if the prosthesis has not loosened but the metal cup may have to be replaced in the event of metal-metal contact between the head and the cup. Prosthesis loosening, wear of the metal cup, or an identified cause of dislocation imply replacing the failing implants. Implantation of the dual mobility system is particularly interesting for patients with a high risk of dislocation or a chronically unstable hip prosthesis. Careful technique is required to reduce or retard the risk of intra-prosthetic dislocation. Conclusion Intra-prosthetic dislocation of a dual mobility socket is an exceptional complication at mid-term. Surgical treatment is required but may be limited to simple insert replacement. Systematic use of this type of implant in young subjects must be carefully examined, but for us, the risk of dislocation does not outweigh the advantages of this original concept of dual mobility. This type of socket remains an useful preventive technique for high-risk hips or for curative treatment of recurrent dislocation.