Is dual mobility associated with an increased risk of revision for infection? Matched cohort of 231 cases of dual-mobility cups and 231 fixed cups.

INTRODUCTION: We used a matched cohort of 231 cases of revision of primary dual-mobility cups (DMC) total hip arthroplasty (THA) and 231 cases of fixed cups (FC) THA, to determine whether (i) revision for infection was more frequent when using DMC-THA than FC-THA; (ii) Causes for revision were significantly different. METHODS: The French Society of Orthopaedics and Traumatology carried out a prospective multicentre study from 2010 to 2011. The inclusion criterion was an exhaustive collection of 1st revision THA (at least 1 component revised, re-revision excluded). 2,044 1st revision cases were prospectively collected; 251 (13.5%) were revision of DMC-THA and 1,793 were revision of FC-THA (87.7%). We defined a matching process (1:1) between the 2 cohorts. 231 DMC-THAs were eligible for comparison with 231 FC-THAs. RESULTS: 47 (20.3%) FC-THAs were revised for infection and 54 (23.3%) DMC-THAs. There was no statistical difference (p = 0.43). 41 (17.7%) FC-THAs were revised for dislocation, compared to 11 (4.7%) DMC-THAs (p<0.001). DISCUSSION: The main finding of our study was that DMC was not associated with an increased risk of revision for infection compared to standard THA. THA revision for infection was not correlated to the type of cup used. It is mandatory to report on comparable types of patients when comparing outcomes. For similar patient profiles (i) DMC-THAs were not revised more often for infection than FC-THA (ii) FC-THAs were revised 4 times more for dislocation than DMC-THA.

Low friction arthroplasty and dual mobility cup: a new gold standard.

INTRODUCTION: Low friction arthroplasty (LFA) introduced by Sir John Charnley was the gold standard for many years. Dislocation and infection are the first causes for early revision. Late failures are polyethylene (PE) wear and loosening. Due to dislocation risk we slowly switched to the use of LFA with dual mobility cups (DMC). The purposes of this study are (1) to assess whether our changes have improved outcomes and (2) what is the new gold standard? MATERIAL AND METHODS: We selected from an observational registry of 1,091 cases of hybrid Charnley total hip arthroplasty (THA). The acetabular component was either DMC in 455 cases or fixed cup (FC) in 636 cases. RESULTS: Three dislocations (0.6%) occurred in the DMC group (none revised). In the FC group 54 dislocated (8.49%) and 20 were recurrent and underwent revision (revision rate 3.14%). In the DMC group, five acetabular and three femoral revisions were performed (revision rate for loosening 1.7%). In the FC group 19 cases underwent acetabular revision, and five cases had femoral component revised (revision rate for loosening 3.7%). DISCUSSION: Charnley's LFA has proven over 50 years of excellent survivorship. To decrease dislocation risk, one suggested increasing femoral head diameter. Gilles Bousquet proposed another way, namely, the DMC concept. Dislocation is no longer a critical issue with DMC as demonstrated in our series and main series. DMC in primary THA is still a subject of debate. Mid-term results do not demonstrate a higher rate of wear than LFA. What is the current gold standard? LFA was and is our current gold standard in association with a DMC.

Revisión acetabular con conservación del componente metálico osteointegrado y cementado de un componente de polietileno: Reporte de una serie de 40 casos

Introducción: Un escenario cada vez más frecuente en la cirugía de revisión protésica de la cadera es hallar un cotilo no cementado fijo con una falla del componente modular de polietileno. Una completa revisión acetabular se presenta como demasiado agresiva cuando el componente metálico es salvable. Cementar un nuevo inserto de polietileno dentro del componente acetabular metálico osteointegrado es una alternativa. Comunicamos los resultados con esta técnica, y sus indicaciones, el modo de realización y las posibles limitaciones. Materiales y Métodos: Entre 2001 y 2011, se cementaron 40 componentes de polietileno dentro de copas no cementadas. Se evaluó radiológicamente y clínicamente a todos los pacientes. El motivo por el que se cementó un inserto fue falla o rotura de mecanismo de captura (11 casos; 27,5%), ganar estabilidad (18 casos; 45%) y falta de disponibilidad del inserto correspondiente (11 casos, 27,5%). Resultados: La tasa de duración del implante sin reoperación a 46 meses de seguimiento fue del 92%. Un paciente (2,4%) sufrió una infección, y dos presentaron inestabilidad (4,8%). No se presentaron aflojamientos hasta el último seguimiento. El puntaje preoperatorio y posoperatorio en la escala de Harris fue de 59 y 80, respectivamente. Conclusiones: Los datos técnicos por considerar para tener éxito son: utilizar un inserto de menor tamaño que el de la copa, cementar insertos texturizados y dejar siempre como mínimo un manto de cemento uniforme de 2 mm. Nuestros resultados preliminares cementando un inserto de polietileno dentro de una copa acetabular osteointegrada parecerían justificar esta técnica de revisión en pos de prevenir la pérdida de capital óseo asociada a la necesidad de recambio de copas osteointegradas.(AU)

Background: Modular liner component failure in fixed shells is an increasingly frequent scenario in prosthetic revision surgery. A complete acetabular revision is too aggressive when the metallic component can be saved. An alternative is to cement a liner within the fixed shell. We report our results using this technique, pointing out its indications, modus operandi and possible limitations. Methods: From 2001 to 2011, 40 polyethylene components were cemented within fixed shells. All patients were radiologically and clinically evaluated. The reasons for which a polyethylene component was cemented were: capture mechanism failure (11 cases, 27.5%), stability (18 cases, 45%) and liner unavailability (11 cases, 27.5%). Results: The survival rate without reoperation after 46 months of follow-up was 92%. One case (2.4%) developed an infection, and two cases evidenced instability (4.8%). The survival rate for aseptic loosening was 100%. The pre-operative Harris score was of 59, increasing up to 80 in the post-operatory period. Conclusions: Technical data to be taken into account for success: use an undersized component, to cement textured components and to leave a uniform cement layer of feat least 2 mm. Our preliminary results cementing a polyethylene component within a fixed shell would seem to justify this revision technique to prevent the loss of bone stock associated with cementless cup revision.(AU)