Aim

S. aureus and coagulase-negative staphylococci are the most frequent bacteria responsible for PJI. In patients with acute PJI (i.e. <1 month following the implantation), DAIR with exchange of removal components followed by a combination of antibiotics that includes rifampin (particularly rifampin+fluoroquinolone) are recommended. Unfortunately, some patients could not receive rifampin due to drug-drug interaction or stopped it due to an adverse event. Finally, it was unclear if the dose and the duration of rifampin influenced the prognosis.

Aims

Microbiological diagnosis of bone and joint infections (BJIs) is pivotal. However, no consensus exists about the best choice for techniques to be used and the best indications for molecular methods. Our objectives were: (i) to compare the performance of various microbiological diagnostic methods (cultural and molecular) on synovial fluid specimens and (ii) to select an algorithm for optimizing the diagnosis of BJIs in adults.

The main causes of total hip arthroplasty (THA) revisions are loosening and instability. Use of a dual mobility cup cemented in a acetabular reconstruction cage device limits the risk of instability and does not hinder the acetabular fixation during THA revisions. The objective of this study was to analyse a retrospective series of 123 THA revisions with antiprotusio cage and dual mobility socket.

Patients and methods: At a mean follow-up of 10 years, we analysed a continuous series of 123 revisions using a reconstruction device (87 Kerboull cross-plates, 12 Burch-Schneider antiprotrusio cages, 24 custom-fit Novae ARM cages associated in all cases with a Novae Stick dual mobility cup cemented into the cage). There were 80 women and 43 males. The mean age at the surgery was 69.2 years old.

PMA score increased from 9.6 +/− 3.06 preoperatively to 14.2 +/− 2. at the follow-up. 9 early dislocations occurred and one late dislocation. At the last follow-up, the X-rays showed nine hardware failures, including one cross-plate fracture, one hook fracture, and one flange fracture. Analysis of the radiological position of the cup showed a mean lowering of 13 mm and a 7 mm lateralisation compared to the preoperative position. 2 revisions for aseptic loosening and 3 for septic loosening were performed.

This study confirms the advantage of dual mobility cups during acetabular reconstruction cemented in antiprotrusio cages as a way to limit, without eliminating, the risk of dislocation. Therefore cemented fixation of dual mobility cups in cages appears to be a reliable short-term option.

Dual mobility significantly reduces the risk of prosthetic instability. This mechanical complication occurs when the prosthetic head moves out from the retentive polyethylene liner, such phenomenon called intra-prosthetic dislocation reports a ten-year incidence of 2% in the literature.

We prospectively analysed all intra-prosthetic dislocations having occurred since 1985 in our department in order to investigate patient- and implant-related risk factors.

91 intra-prosthetic dislocations occurred with NOVAE (SERF) cups in 85 patients of mean age 50.7 years. Intra-prosthetic dislocation occurred after a mean period of 8.8 years.

A PRO (SERF) stem was implanted in 56 cases and a PF (SERF) stem in 35. The stems were different from one another in their neck diameter and material: 13 mm titanium neck and 16 mm stainless steel neck respectively.

When taking both prosthetic features into account, no significant difference could be established regarding the time between implantation and dislocation.

Comparison between these two prosthetic features was performed by means of two continuous homogeneous series which included 240 patients implanted with PF stems and 382 patients with PRO stems. At a mean 15-year follow-up, the two series reported a non-statistically different intra-prosthetic dislocation rate of 4%.

In both series, young age and large diameter cups were considered predisposing factors for intra-prosthetic dislocation.

Therefore, unlike suggested by several authors, prosthetic neck material and diameter do not appear as the main predictors for intra-prosthetic dislocation which is highly promoted by patient-related features.

The concept of stainless steel dual mobility cups in total hip arthroplasty has demonstrated very low long-term instability rates and a 98% survival rate after 12 years. We systematically implanted titanium alloy acetabular cups during a one year period. The purpose of our retrospective study was to report the 18-year clinical outcome data in a homogeneous and continuous series of 103 primary total hip replacements after implantation of a cementless titanium cup.

All patients were implanted with NOVAE Ti (SERF) cups made of titanium alloy combined with a retentive polyethylene liner and a 22.2 mm cobalt chrome prosthetic head. Mean patient age at the time of surgery was 53 years. All patients were clinically and radiographically evaluated.

The overall 18-year actuarial cup survival rate with a 95% confidence interval was 87.4%. At last follow-up, there was no evidence of implant instability whereas acetabular aseptic loosening was reported in one case and high wear of the retentive liner in 9.

The results of this investigation confirmed the long-term stability of dual-mobility implants. The main limitation of this system was early wear of the polyethylene liner in contact with the titanium metal back and reaction with third body along with loss of liner retentivity. In our study, titanium demonstrated favourable osteointegration properties but poor tribologic characteristics, therefore suggesting its interest at the bone-cup interface only.

Purpose of the study: In 1975, Bousquet and Rambert invented the concept of dual mobility to reduce the risk of dislocation by changing the fixed insert on a Charnley implant to a mobile liner within a metal back shell held onto the femoral head by a retaining collar. This enabled implant recipients to maintain their intense activities without restriction after a first-intention procedure and to overcome muscle deficits after revisions. The screw-on PF stem was introduced in 1985. The purpose of our study was to demonstrate the long-term advantages and failures of this combination.

Material and method: This series included 240 hips with a PF stem and a Novae metal back cup. This was a retrospective analysis of a homogenous group of consecutive patients who underwent surgery from 1985 to 1990 (mean follow-up 22 years). Mean age at implantation was 56.7 years. This is the largest series, with the longest follow-up reported to date with dual mobile cups. The main indication was degenerative joint disease (79%) then osteonecrosis (11%). The implant was made of 316 L stainless steel. The PF was composed of the stem, a 22 mm diameter monobloc modular base and a 16 mm diameter neck. The tripodal Novae metal back cup was alumina coated. Preop, intraoperative and postop data were analysed. Clinical and radiographic follow-up (lucent lines, implant position) were noted at last follow-up. The Charnley, PMA, Devane and Sedel scores were noted.

Results: The preoperative PMA was 10.8, reaching 16.9 at last follow-up. The Devane score remained unchanged at 3. The mean Brooker score was 1.2. There were no cases with crural pain. Survival at last follow-up was 80%. There were no cases of dislocation, 18 intraprosthetic dislocations (4% at 9.25 years), four revisions of implant wear (1.7% at 19 years), five femoral revisions (2%), two infections (0.8%), nine patients lost to follow-up (4%) and 100 deaths.

Conclusion: The PF stem has a remarkable survival. The overall survival is comparable with series having an equivalent follow-up. The dislocation rate was zero, demonstrating the superiority of the dual mobility concept. There were several intraprosthetic displacements which came later than with Profil stems (role of the neck on the lip). The main complication was acetabular loosening, attributed to insufficient secondary fixation, improved later by adjunction of hydroxyapatite. Wear of the dual mobility cup should be modelised to define the role of osetolysis in these failures.

Background: Implant instability is a major complication of total hip arthroplasty. The concept of dual articulation invented by Prof. Bousquet in 1974 is now increasingly recognized in Europe. This concept has proved to provide high stability after total hip arthroplasty revision, and to successfully address chronic instability after total hip arthroplasty. The aim of our study was to evaluate the incidence of prosthetic instability in a consecutive homogeneous series of three hundred and eighty four hips primary cases with a mean follow-up of fifteen years.

Methods: Three hundred and eighty four hips have been implanted with a dual articulation acetabular cup system. This system consists of a cementless acetabular shell, and a polyethylene liner which freely rotates within the shell and positively captures the prosthetic head. It was a consecutive and homogeneous series of cases. Only primary cases were included in the study. A final evaluation was performed at the last follow-up. Implant survival was evaluated using the Kaplan-Meier method (p< 0.05), with surgical revision for aseptic loosening as the endpoint for failure. We have evaluated the incidence of instability by prospectively listing all the episodes of implant instability.

Results: At the last follow-up, 6 patients could not be located and 92 were deceased.

Mean follow-up was 15.3 years. The mean Merle d’Aubigner hip score was 16.3±1.8 at the latest follow-up. There was no early or late instability. Radiologically, there were 31% of severe granuloma formation extending beyond zones I and VII. However, granuloma remained asymptomatic in all of the cases and did not require surgical revision of the femoral component. On the acetabular side, late complications occurred: aseptic loosening (3.3%), intra-prosthetic dislocation (3.6%), polyethylene wear that required replacement of the liner (1.8%). Survival of dual-articulation acetabular system with surgical revision for aseptic loosening as the end-point for failure was 96.4% at 15 years and 94.9% at 18 years postoperatively (p< 0.05).

Conclusion: Our consecutive homogeneous series proves the good long-term behaviour of dual-articulation acetabular components in primary arthroplasty. Their excellent survivorship rate at 18 years increases our confidence in this concept. Considering the absence of episodes of prosthetic instability in our series, we can rightly claim that the goal of decreasing instability has been achieved.