Charnley femoral cemented stem with a permeable and resorbable cement restrictor and low-viscosity cement - Clinical and radiographical evaluation of 100 cases at a mean follow-up of 6.55 years.

INTRODUCTION: In 1979, in his first book dealing with low-friction arthroplasty (LFA), Charnley highlighted the use of a cement restrictor. Breusch and Malchau described in 2005 the "second-generation cementing technique." The main objective of this study was to report on the clinical survival of 100 cases of Charnley femoral component implanted in 2007 and 2008 using a permeable and resorbable cement restrictor and a low-viscosity antibiotic-loaded cement. The secondary objectives were to analyze the complications and side effects and the accuracy of the device positioning. MATERIAL AND METHODS: This was a monocentric retrospective review of a prospectively compiled database. Diaphyseal restrictor was biodegradable and permeable to gas, blood, and fluids to avoid intramedullary over pression during cementation. The cement was a low-viscosity antibiotic-loaded cement. Among 3555 patients, we selected the first continuous 100 cases of patients where we implanted the device. Survival probability was computed according to Kaplan-Meier method. RESULTS: Mean follow-up was 6.55 ± 2.6 (range 1-11). Considering femoral component revision as the endpoint, survival rate was 100%. No patients died intraoperatively, none in the first month and the first year after surgery. No early periprosthetic fractures have been reported. DISCUSSION: As described initially by Charnley, the use of a cement restrictor was highly recommended through the different generations of cementing techniques. Hypotensive episodes and cardiac arrest have been reported during cement insertion. In our series, we did not deplore any adverse effect related to the cementation. CONCLUSION: Our study demonstrates a 100% survival rate of a cemented femoral component without adverse effects when using routinely a resorbable and permeable cement restrictor and a low-viscosity cement. Bone cement is still a fantastic ally for the surgeon and the patients.

The cross technique for the positioning of Kerboull plate in acetabular reconstruction surgery.

Acetabular reconstruction aims at filling bony defects and positioning the acetabular component in its anatomical place. To this, the use of Kerboull plate would give an automatic optimal positioning while reconstructing the acetabular cavity. We developed a technique, the cross technique, that approaches acetabular reconstruction in a systematic way. It consists of placing the KP following its cross design, in reference to a vertical plane (hook, center, palette) and a horizontal plane (horizontal flanges). The cross technique has three steps; the preparation of the acetabular cavity, the cross technique itself and cementation. We recommend a downsizing of the plate in relation to the size of the acetabular cavity in addition to another downsizing of the acetabular implant in relation to the plate size whenever a dual mobility cup is used.

How is patella height modified after total knee arthroplasty?

INTRODUCTION: Since the first measurement method of patella height in 1929 (Janssen), more than 16 methods have been described. Most of these measures are not suitable to measure patella height after total knee arthroplasty (TKA). One of us (JC) modified the original Caton Deschamps (oCD), index with a new relative index called modified Caton Deschamps (mCD) index, by using new landmarks. The purpose of this study was to determine how patella height is modified after TKA. MATERIAL AND METHOD: Sixty primary TKAs were consecutively prospectively enrolled. One type of implant was used (cementless postero-stabilized TKA, rotating plateau, cemented patella resurfacing). Patient's characteristics, functional and radiological outcomes were recorded pre-operatively and at one year follow-up. Pre-operative and post-operative outcomes were compared by paired t-test. Post-operative outcomes were compared between groups by one-way analysis of variance. RESULTS: Average difference between pre and post-operative mCD was 0.19 in this series. In 81.7% of cases, patella was lowered. Patients were classified in three groups according to patella height lowering. Between these three groups, no significant statistical differences (IKS score knee and function, range of motion) could be identified. DISCUSSION: In TKA, patella assessment in sagittal plane is as important as frontal or horizontal planes. True patella infera (TPI) is mostly due to patella tendon shortening measured by oCD. Pseudo patella infera (PPI) measured by mCD is mostly due to joint line elevation (over femoral cut with an over thickness of the tibial component). In this study a moderate patella lowering (minor than 15%) does not have a significant impact on the functional results (IKS, ROM) nevertheless in 80% patella is lowered. The next step will be to analyze precisely what factors are influencing this lowering and what prevention could be suggested in primary and revision TKA.

All dual mobility cups are not the same.

PURPOSE: Although the natural history of dual mobility has been exclusively borne for 20 years by a single company (due to industrial ownership), the concept has undeniably been very widely popularised with nearly 40 cups on the French market which should be regarded as a weight bearing surface, both broadly and in their own right. However, within the same original idea, these implants are not all identical (design, material, fixation ect.).The aim of this work is to propose a classification of different dual mobility cups by distinguishing between thegeneral characteristics of a conventional cup and those particular to this type of implant. METHODS: By comparison with a standard metal-back cup, dual mobility is based on at least one additional interface corresponding to the mobility of the polyethylene insert in the concavity of the acetabular cup called the outersurface. Design, constitutive material, fixation of the cup and characteristics of the retentive insert are analysed through the published results. RESULTS: The complications associated, in particular, the intraprosthetic dislocation and to a lesser extent fixation failures undoubtedly condemned the dissemination of the dual mobility concept, as witnessed by the fact that despite the precedence of this 40-year old concept, the overriding majority of publications (more than 95%) have only appeared in the last ten years. CONCLUSION: The latest generation of dual mobility cups combines: 1) a cast chrome-cobalt alloy cup covered with a bilayer coating of porous titanium and hydroxyapatite for long-term press-fit fixation to 2) an insert designed to eliminate all of the risks of intraprosthetic dislocation, whilst keeping all of the elasticity properties of the polyethylene, which has demonstrated its medium and long term effectiveness on preventing instability by overcoming other complications.

The evolution of outcomes and indications for the dual-mobility cup: a systematic review.

PURPOSE: Instability following total hip arthroplasty remains a common and disabling complication. The dual mobility cup (DMC) allows a reduction in the dislocation rate. An increasing number of studies have been undertaken to better understand DMC long term outcomes and complications. The goal of this systematic review was to clarify its different uses and outcomes according to the indications. METHODS: A comprehensive literature review was performed using the keywords 'dual mobility' and 'tripolar cup' with no limit regarding the year of publication. One hundred seventy six publications were identified. RESULTS: Current literature shows that "contemporary" dual mobility cup are a significant indication to manage instability following primary and revision hip arthroplasty. Survivorship at midterm is comparable to other articulations for primary THA, but is more difficult to evaluate in revision. Intra-prosthetic dislocation, wear, and loosening are now uncommon with new generations of DMC. CONCLUSIONS: Compared to previous generations of DMC, the current "contemporary" DMC presents a significant improvement. Current literature reveals a tendency to increase the indications but further studies with long term follow up remain important to consolidate these findings.

Ceramic bearings with bilayer coating in cementless total hip arthroplasty. A safe solution. A retrospective study of one hundred and twenty six cases with more than ten years' follow-up.

PURPOSE: Using a ceramic-ceramic bearings, cementless total hip arthroplasty (THA) has provided good clinical results. To ensure longevity a good quality fixation of the implants is mandatory. Different surface treatments had been used, with inconsistent results. We hypothesized that a "bilayer coating" applied to both THA components using validated technology will provide a long-lasting and reliable bone fixation. METHODS: We studied the survival and bone integration of a continuous, single-surgeon, retrospective series of 126 THA cases (116 patients) with an average follow-up of 12.2 years (minimum 10 years). The THA consisted of cementless implants with a bilayer coating of titanium and hydroxyapatite and used a ceramic-ceramic bearing. RESULTS: With surgical revision for any cause (except infection) as the end point, THA survival was 95.1 % at 13 years. Stem (98.8 %) and cup (98.6 %) survival was similar at 13 years. Bone integration was confirmed in 100 % of implants (Engh-Massin score of 17.42 and ARA score of 5.94). There were no instances of loosening. Revisions were performed because of instability (1.6 %), prosthetic impingement or material-related issues. CONCLUSION: A bilayer titanium and hydroxyapatite coating provides strong, fast, reliable osseo integration, without deterioration at the interface or release of damaging particles. The good clinical outcomes expected of ceramic bearings were achieved, as were equally reliable stem and cup fixation.

Patellar height assessment in total knee arthroplasty: a new method.

INTRODUCTION: We described in 1981 a method to evaluate patellar height in normal and symptomatic knees on sagittal X-ray view. This index is a frequently used method, yet it is not suitable after a total knee arthroplasty (TKA). MATERIAL AND METHOD: The original method measures the distance between the distal margin of the articular surface of the patella (point A) and the anterosuperior angle of the tibial plateau (point T), then the length of the patellar articular surface (AP). The index is AT/AP ratio (normal values range from 0.8 to 1.2). After TKA, the T landmark is no longer available, so we must define a new T' landmark. This point is situated at the intersection between the line perpendicular to the tibial posterior cortex elevated at the tip of the fibular head and the tibial anterior cortex. This remarkable landmark can be identified before and after TKA, with a new relative index AT'/AP ratio. This modified method allows the comparison of patella height before and after TKA. RESULTS: We have used this modified index with the collaboration of several authors during the testing of different models of TKA, with an accurate reproducibility. Repeatability (usually called intra-observer reliability) was good, with intra-class correlation coefficients (ICCs) between 0.58 and 0.75 among the observers. Reproducibility (usually called inter-observer reliability) was also considered as good, with ICC ranging from 0.64 to 0.72. DISCUSSION: Patella height measurement has to be assessed with the original method (AT/AP) to detect patella infera that could influence the surgical approach. The correlation between original and modified indexes has to be assessed. The modification of patella height after TKA could be evaluated through the modified index and compared with functional results.

Prospective study of the cementless "New Wave" total knee mobile-bearing arthroplasty: 8-year follow-up.

One of the main factors affecting the survival of a total knee arthroplasty (TKA) is the fixation method. The constraints placed on the bone-implant interface of a mobile-bearing TKA must be taken in account during the design and evaluation phases. For more than two decades, calcium phosphate ceramics, particularly hydroxyapatitis, have been used in Europe to accelerate the bone integration of cementless implants. A prospective study of patients continuously recruited by three senior surgeons at three French private hospitals has been carried out. There were no exclusion criteria. Eighty-four (84) cementless mobile-bearing total knee prosthesis of the brand "New Wave" were implanted in 74 patients over a 2-year period (2004-2005). Implant survival at 8 years was 95% [with a confidence interval of 95%: 80.2-96.4%] when revision for any cause was defined as the endpoint. Five implants required surgical revision to exchange all or part of the implant: two for aseptic loosening of tibial component, one for osteolysis, one for persistent flessum (30°) and one for tibial periprosthetic fracture. Completely integrated implants and event-free outcomes were recorded in 91.4% of the cases at eight-year follow-up. The Hospital for Special Surgery score significantly improved from 56.8/100 points before the surgery to 83.9/100 points at the last follow-up (p < 0.05). Radiologically, only one patient had radiolucent lines around the tibial and femoral components. This cementless total knee prosthesis yielded good medium-term survival. Cementless arthroplasty can generate solid and durable bone fixation in this total weight-bearing implant, and it seems that the hidroxyapathitis surface in this series stimulate the bone integration at the bone-implant interface.

Cementless dual-mobility cup in total hip arthroplasty revision.

PURPOSE: Dislocation is a frequent complication in total hip arthroplasty (THA) revision. Cup fixation is the second concern. In order to know outcomes at two years, we prospectively followed a continuous series of 78 patients to demonstrate that cementless dual-mobility cup (DMC) used in revision THA is safe as regards dislocation risk and bone fixation. METHOD: We enrolled 78 consecutive patients (79 cases) in a prospective study. Mean interval between index surgery and revision was 12.9 years. Mean age at revision was 75.5 years. Two types of cementless DMC were used: a standard DMC in 68 cases with low-grade bone defect (Paprosky grade 1 and 2), and a specific design reconstruction DMC in 11 cases with severe bone loss (Paprosky grade 3). RESULTS: At two years of follow-up, 68 patients were reviewed; four were lost to follow-up., and six patients were deceased. We identified three types of situations at risk:standard risk (33 cases), Paprosky grade 1 or 2; medium risk (37 cases), revision for recurrent instability (21), periprosthetic fractures (14) or severe loosening Paprosky grade 3 without femorotomy (2); high risk (nine cases), revision for severe loosening with a femorotomy. One (1.3%) patient dislocated her hip at one month without recurrence. Revision rate for dislocation was 0%; two (2.7%) early mechanical failures occurred. CONCLUSION: Considering outcomes of this series, cementless DMC can be suggested in THA revision surgery.

A comparative and retrospective study of three hundred and twenty primary Charnley type hip replacements with a minimum follow up of ten years to assess whether a dual mobility cup has a decreased dislocation risk.

PURPOSE: Mid- and long-term follow-up of Charnley total hip arthroplasty (THA) demonstrated good functional results with 85 % survivorship at 25-year follow-up. However, dislocation still remains an unsolved problem. Dislocation may occur throughout the patient's and implant's life. The aim of this study is to answer the question: does a dual mobility cup (DMC) decrease the dislocation risk? METHODS: We report comparative results at ten years of follow-up of two groups of primary cemented Charnley-type THA, one with a standard polyethylene cup (group 1, n = 215) and the other one with a DMC (group 2, n = 105). RESULTS: In group 1, 26 dislocations (12.9 %) occurred. In group 2 only one dislocation (0.9 %) occurred. This dislocation was successfully reduced by closed reduction, without any recurrence. This difference was statistically significant (p = 0.0018). In group 1, the reason for revision was recurrent dislocation in 21 cases. Five patients were revised for other reasons. The global revision rate was 12.9 %. In group 2, two patients needed revision surgery for aseptic loosening. The global revision rate was 2.1 %. This difference was statistically significant (p = 0.054). The goal was reached for the patients of group 2 who had more risks factors for dislocation (age, aetiology, American Society of Anesthesiologists and Devane scores) than those of group 1. CONCLUSIONS: When using a DMC, we observed a low rate of dislocation in primary THA (0.9 %). This surgical choice seems to be a safe and effective technique in Charnley-type THA, especially in a high-risk population.