Infection recurrence factors in one- and two-stage total knee prosthesis exchanges.

PURPOSE: Revision of infected total knee replacements (TKR) is usually delayed for a period in which the joint space is filled with an antibiotic-loaded acrylic spacer. In contrast, one-stage re-implantation supposes immediate re-implantation. Formal comparisons between the two methods are scarce. A retrospective multi-centre study was conducted to investigate the effects of surgery type (one-stage vs. two-stage) on cure rates. It was hypothesised that this parameter would not influence the results. METHOD: All infected TKR, treated consecutively between 2005 and 2010 by senior surgeons working in six referral hospitals, were included retrospectively. Two hundred and eighty-five patients, undergoing one-stage or two-stage TKR, with more than 2-year follow-up (clinical and radiological) were eligible for data collection and analysis. Of them, 108 underwent one-stage and 177 received two-stage TKR. Failure was defined as infection recurrence or persistence of the same or unknown pathogens. Factors linked with infection recurrence were analysed by uni- and multi-variate logistic regression with random intercept. RESULTS: Factors associated with infection recurrence were fistulae (odds ratio (OR) 3.4 [1.2-10.2], p = 0.03), infection by gram-negative bacteria (OR 3.3 [1.0-10.6], p = 0.05), and two-stage surgery with static spacers (OR 4.4 [1.1-17.9], p = 0.04). Gender and type of surgery interacted (p = 0.05). In men (133 patients), type of surgery showed no significant linkage with infection recurrence. In women (152 patients), two-stage surgery with static spacers was associated independently with infection recurrence (OR 5.9 [1.5-23.6], p = 0.01). Among patients without infection recurrence, International Knee Society scores were similar between those undergoing one-stage or two-stage exchanges. CONCLUSION: Two-stage procedures offered less benefit to female patients. It suggests that one-stage procedures are preferable, because they offer greater comfort without increasing the risk of recurrence. Routine one-stage procedures may be a reasonable option in the treatment of infected TKR. LEVEL OF EVIDENCE: III.

Chronic infection of unicompartmental knee arthroplasty: one-stage conversion to total knee arthroplasty.

BACKGROUND: The main reasons for revision of unicompartmental knee arthroplasty (UKA) are loosening, wear, extension of osteoarthritis to another compartment, and infection. There have been no studies of the management of infected UKA, whose incidence varies from 0.2% to 1%. Our objective was to describe infection-related and mechanical outcomes of chronic UKA infection managed by one-stage conversion to total knee arthroplasty (TKA). PATIENTS AND METHODS: Consecutive patients with chronic UKA infection managed by one-stage conversion to TKA between January 2003 and December 2010 were included in a retrospective single-center study. All patients also received appropriate dual antibiotic therapy intravenously for 6 weeks then orally for 6 additional weeks. RESULTS: During the study period, among 233 cases of infected knee arthroplasty managed at our center, 9 met the study inclusion criteria. The UKA was medial in 6 patients, lateral in 2, and patellofemoral in 1. Median age was 67 years (range, 36-83 years) and median infection duration was 9months. In 5 patients, previous treatment with synovectomy, joint lavage, and antibiotics had failed. The following bacteria were identified: oxacillin-susceptible Staphylococci, n=6 (S. epidermidis, n=4; S. capitis, n=1; and S. lugdunensis, n=1); nutritionally deficient Streptococcus, n=1; Enterococcus durans, n=1; and Escherichia coli, n=1. Median follow-up was 60 months (range, 36-96 months). No patient experienced recurrent infection or required revision surgery for infection. No medical complications limiting the use of appropriate antibiotic therapy were recorded. The mean preoperative knee and function scores were 60 and 50, respectively; corresponding mean postoperative values were 75 and 65, respectively. DISCUSSION: UKA infection involves both the prosthesis and the native cartilage, neither of which can be treated conservatively in chronic forms. After identification of the causative organism, synovectomy and joint excision followed by same-stage TKA and combined with appropriate antibiotic therapy for 3 months is effective. LEVEL OF EVIDENCE: IV, retrospective cohort study.

Continuous high-dose vancomycin combination therapy for methicillin-resistant staphylococcal prosthetic hip infection: a prospective cohort study.

Few data are available on treatment and outcome of methicillin-resistant (MR) staphylococcal prosthetic joint infections. Vancomycin remains the treatment of choice for these infections, but its efficacy and safety in bone-and-joint infections are insufficiently documented. We conducted a prospective cohort study on 60 patients treated between November 2002 and December 2008 for chronic MR staphylococcal (44 S. epidermidis, nine other coagulase-negative Staphylococcus and seven S. aureus) prosthetic hip infections (PHIs). Twenty-two patients had previously undergone surgery for their PHI and 21 had previously received antibiotics. All patients had surgery (exchange arthroplasty for 58 patients, resection arthroplasty for two) and received an antibiotic regimen combining high-dose continuous intravenous vancomycin infusion (target serum concentration 30-40 mg/L) with another antibiotic for 6 weeks, followed by an additional 6 weeks of oral intake. Two years after surgery, infection was considered cured in 41 (68%) patients and only two relapses occurred after one-stage exchange arthroplasty. Nineteen (32%) patients experienced nephrotoxicity that was generally mild (RIFLE class R for 14 patients, class I for four patients and class F for one patient) and most often reversible. Continuous high-dose intravenous vancomycin combination therapy is an effective, feasible and reasonably safe treatment of chronic MR staphylococcal PHI.

Infected total hip arthroplasty revision: one- or two-stage procedure?

INTRODUCTION: Better outcomes have been reported for two-stage total hip arthroplasty (THA) revision for infection. However, one-stage revision arthroplasty remains an attractive alternative option since it requires only one operation. A decision tree has been developed by the authors in order to determine which type of surgical procedure can be performed safely. The goal of this study was to assess this decision tree for THA replacement in the case of a peri-prosthetic infection. HYPOTHESIS: A one-stage procedure may be as successful as a two-stage procedure provided some criteria are fulfilled. METHODS: A prospective study included 84 patients, all diagnosed with infected THA who had prosthesis replacement. A one-stage exchange was performed in 38 cases and a two-stage procedure in 46 cases. A two-stage procedure was decided in the case of important bone loss or unidentified germ. Postoperatively, patients received intravenous antibiotics (six weeks), then oral antibiotics (six weeks). The main evaluation criterion was the rate of infection eradication at 2 years minimal follow-up since surgery. If new infection was suspected, a hip aspiration was performed to determine whether it was non-eradication (same germ) or a new re-infection (other germ), which was not considered as a failure. RESULTS: The initial infection was cured in 83 out of 84 patients (98.8%), 38 (100%) for the one-stage group and 45 (97.8%) for the two-stage group. Three patients were re-infected with different germs in the two-stage group. Eighty out of 84 (95.2%) patients were infection free, all patients (100%) of the one-stage group and 42 patients (91.3%) of two-stage group. DISCUSSION: If some selection criteria were respected, a high success rate in THA replacement for infection may be achieved with a one-stage procedure. It permits to reduce the costs with no loss of chance for the patients. The decision tree was validated. LEVEL OF EVIDENCE: Level III; prospective case control study.

Infected total hip arthroplasty treated by an irrigation-debridement/component retention protocol. A prospective study in a 12-case series with minimum 2 years' follow-up.

INTRODUCTION: Treatment of infection after total hip replacement (THR) is complex and costly. Debridement with component retention is an attractive solution. Success rates in the literature vary widely (18-90%) according to patient selection criteria. The present prospective study assessed the selection criteria used in our department. METHODS: A prospective study included all patients (n=210) surgically managed for infection following THR between November 2002 and December 2008. Patients underwent debridement in case of acute infection: i.e., early postoperative infection within 1 month of THR, or secondary hematogenic infection with less than 2 weeks' evolution. Beyond this deadline or in case of implant loosening, implant replacement was performed. The debridement series thus comprised 12 patients (mean age, 69 ± 11.3 years; mean evolution from contamination was 4.8 ± 3.5 days). Bacteriologically adapted antibiotherapy was administered for 6 weeks intravenously followed by 6 weeks per os. Mean follow-up was 40 ± 23 months. No patient was lost to follow-up. The success criterion was apparent eradication of infection at a minimum 2 years, defined by absence of clinical, biological or radiological signs of infection and of death attributable to infection or treatment. Where infection was suspected, hip aspiration or peroperative sampling determined recurrence (identical bacterium) or reinfection (different bacterium). RESULTS: There were nine cures (75%) and three failures. Mean Postel Merle d'Aubigné Score, at end of follow-up, was 17 ± 2. The three failures involved the same bacteria (two streptococci [one group B, one group G] and one Enterococcus faecalis) as implicated in the primary infection. DISCUSSION: The present results are comparable to those in the literature but poorer than for implant exchange. The technique remains, however, an interesting alternative, allowing less complex surgery and lower cost. CONCLUSION: Patient selection criteria need refining so as to increase success rates with this technique. LEVEL OF EVIDENCE: Level IV; prospective non-randomized non-comparative study.

Arthroplasty following a septic arthritis history: a 53 cases series.

INTRODUCTION: The most feared complication of arthroplasty after septic arthritis (active or quiescent) on a degenerative joint is septic failure, but this risk is difficult to assess. The aim of the present study was to analyze the results of arthroplasties after septic arthritis of native knee and hip joints, in terms of functional results and infection control and to seek eventual risk factors of failure. PATIENTS AND METHODS: Fifty-three cases of septic arthritis treated by arthroplasty (31 knees and 22 hips) were retrospectively included. In case of evolutive septic arthritis (30 cases: 17 knees and 13 hips) failing to react to conservative treatment, arthroplasty was performed in a 2-stage procedure (a mean interval of 6 weeks between stages, and an associated antibiotic therapy for a mean 3 months were routinely respected). In case of previous arthritis considered to be cured (23 cases: 14 knees and nine hips), arthroplasty was performed with a 1-stage procedure, observing a mean interval of 5 years after the initial septic arthritis, and antibiotic therapy maintained until definitive microbiological results were obtained from joint cultures samples at surgery. No patients were lost to follow-up; minimum follow-up was 2 years, for a mean of 5 years. The final results were assessed in terms of functional outcome (on PMA functional score for hips and IKS score for knees) and successful eradication of infection. RESULTS: Two-stage arthroplasty was successful in 26 of the 30 cases of evolutive septic arthritis (87%), while the 1-stage procedure was successful in 22 of the 23 cases of quiescent septic arthritis (95%) (NS). Functional results were very good. No significant difference in functional outcome or successful eradication of infection was found between the 1- and 2-stage procedures. No significant difference in final outcome in terms of infection eradication was found between knees and hips. No clinical, microbiological or treatment-related criteria emerged as risk factors for septic failure. DISCUSSION: Arthroplasty after septic arthritis of the knee or hip using the present protocol (2-stage implantation in case of evolutive septic arthritis and a 1-stage procedure in case of quiescent septic arthritis) achieved very good functional results with a success rate of 87% for sepsis control in evolutive septic arthritis and of 95% in quiescent septic arthritis. LEVEL OF EVIDENCE: Level IV retrospective or historical series.

[Infection on continuous bone of lower limb: 127 cases]. / Infection osseuse sur os continu au niveau du membre inférieur: a propos de 127 cas.

PURPOSE OF THE STUDY: Infection on continuous bone is a specific diagnostic and therapeutic entity. Treatment requires debridement of infected and necrotic soft tissue and bone, dead space management, effective antibiotic therapy in the bone and good skin coverage with well-vascularized tissues. Results of treatment of infection on continuous bone of the lower limb are presented in this series. MATERIAL AND METHODS: This retrospective series included 127 cases of osteomyelitis affecting continuous bone of the lower limb (tibia or femur). Septic nonunion and infected arthroplasties were excluded. All patients underwent surgery. The therapeutic protocol was based on debridement, filling of the osteomyelitic cavity as needed (flap, bone grafting, foreign material) and skin cover (by direct closure or flap). Antibiotics were given systematically. Patients were reviewed at minimum two years follow-up. RESULTS: Osteomyelitis was located on the tibia in 66% and was posttraumatic in 75% of cases. Localized osteomyelitis (type III of the Cierny-Mader anatomic classification) was found in 50% of patients. Staphylococcus aureus was the causal agent in 66% of cases. Flaps were performed in more than half of cases and most of them were local flaps. Systematic antibiotic therapy was given for an average three months. With an average four years follow-up, eradication of the infection was obtained in 80% of patients. Ten patients were lost to follow-up. No statistical difference was noted for final outcome according to the physiological hoste class, the anatomic localization (tibia or femur), bacteriological findings, duration of antibiotics, use of flaps, or filling of the osteomyelitic cavity. Treatment of type I and II osteomyelitis was more successful than type III or IV infection (NS). Failure rate increased with the number of previous surgical procedures (p=0.02). DISCUSSION: Infection on continuous bone is a characteristic entity, rarely clearly separated from other bone infections in reported series that combine these infection with septic nonunions and infected arthroplasties. Surgery is essential and is based on quality debridement. The use of flaps (for both dead space management and skin coverage) improves the results for the treatment of such infections but long-term follow-up is needed for a more accurate assessment of success rate.

[Results of reimplantation for infected total knee arthroplasty: 107 cases]. / Résultats des changements de prothèse de genou pour infection: à propos de 107 cas.

PURPOSE OF THE STUDY: The purpose of this study was to assess the results of reimplantations of total knee arthroplasties complicated by infection. Outcome was assessed in terms of eradicated infection and function. MATERIAL AND METHODS: This retrospective multicentric study included 107 cases of infected total knee arthroplasties treated by changing the implants. Seventy-seven patients had a two-stage revision and thirty had a one-stage procedure. Patients were reviewed with a minimal 2-year and an average 52-month follow-up. RESULTS: Revision arthroplasty (one- or two-stage) eradicated infection in two out of three patients. With a two-year follow-up, revision arthroplasty was successful in 77% of patients without any sepsis risk factor, in 65% of patients with one risk factor and in 33% of patients with at least two risk factors. After reimplantation for total knee arthroplasty infection, overall function outcome was good (KS knee score: 74.8 after two-stage revision and 75.5 after one-stage revision, NS). After two-stage procedures, the knee outcome was excellent in one-third of patients, good in another third and fair or poor in the final third. After one-stage reimplantation, 40% of the knees had an excellent outcome, 30% a good outcome and 30% a fair or poor outcome. Regarding functional outcome, overall results were fair (KS function score 62.5 for one-stage and two-stage revisions). Functional outcome was fair or poor in 42% of patients with a two-stage procedure and in 55% of patients with a one-stage revision (NS). DISCUSSION: Our study was unable to disclose any difference between one-stage and two-stage revision for eradicating infection. Unfavorable systemic and local conditions decreased the rate of success after revision total knee arthroplasty for infection. Length of infection before reimplantation, number of surgical procedures and bacterial virulence or resistance were not, in our series, predicting factors for failure of septic revision total knee arthroplasty. No difference was found for the clinical and functional results between one-stage and two-stage procedures. Functional outcome was fair or poor for half of the patients after septic revision total knee arthroplsty. The use of an external device between the two procedures for two-stage revision significantly decreased the functional outcome compared with the use of a spacer. Articulated spacers did not offered any advantage compared with a static spacer for functional outcome.

Locomotor and exploratory activity in three inbred strains of mice from young adulthood to senescence.

Nine variables measuring activity and exploratory behavior were collected for nine independent groups of three inbred strains of mice (BALB/c, C57BL/6, and DBA/2) at three ages (150, 400, and 750 days). An analysis of variance measuring differences of performances and a covariance analysis estimating the evolution of scores with age shows that (1) some variables are unaffected by age; (2) a strain-age interaction is observed for some variables; (3) some groups do not exhibit any age-related change for certain variables; and (4) the level of ability of age-related behavior varies across groups. These data argue for rejection of a general factor of aging and suggest that we are dealing with two distinct phenotypes: performance, and age-related modification of the performance, which therefore are not linked.

Genetics and senescence. I. Age-related changes in activity and exploration in three inbred strains of mice.

Exploratory, locomotor and ambulatory activities were measured in nine independent groups of three inbred strains of mice (BALB/cBy, C57BL/6J and DBA/2J), at three different ages (150 days, 400 days and 750 days). The results show that for two of the three variables, the age-related changes present different patterns as a function of strain. The genetic and/or environmental correlates of the reactivity to aging may thus depend on the behavioral trait under study.

A note on the genetics of a unilateral senile cataract in mice.

Unilateral cataracts were investigated in 750 day-old BALB/c, C57BL/6 and DBA/2 mice, and the six reciprocal crosses between these strains. This abnormality of the lens appears to be inherited additively in the cross DBA/2xBALB/c (with incomplete penetrance in DBA/2 and F1 mice) but as a completely recessive character in the cross DBA/2xC57BL/6. The mode of inheritance may depend on the genetic background against which this phenotype is expressed, unless this abnormality is inherited as a threshold character. Aged DBA/2 mice may constitute a useful model for senile unilateral cataract, probably caused by early uveitis.