Two-stage reimplantation for the salvage of infected total knee arthroplasty. 1983

Static spacers play a crucial role in the treatment of complex periprosthetic joint infections of the knee

PURPOSE

To determine the superior spacer design, a growing number of studies are comparing treatment results between patients having been treated with articulating and static knee spacers in the setting of two-stage revision for periprosthetic joint infection (PJI). In contrast, the primary objective of this study was to compare preoperative characteristics between patients from both spacer groups and examine whether significant differences were present prior to spacer implantation.

METHODS

This retrospective, single-centre, cohort study examined the preoperative situation of 80 consecutive knee PJIs between 2017 and 2020. All patients underwent two-stage revision, with 35 (44%) receiving an articulating and 45 (56%) a static spacer.

RESULTS

No significant differences were observed in terms of patient gender (p = 0.083), age (p = 0.666), comorbidity (p = 0.1) and preoperative clinical function (p = 0.246). Static spacers were significantly more often used in the presence of a periarticular fistula (p = 0.033), infection of a revision implant (p < 0.001), higher degree of bone loss (p < 0.001) and infection caused by a difficult-to-treat pathogen (p = 0.038). Complication and revision rates were similar for both spacer types during the interim period, while patients with articulating spacers demonstrated a superior clinical function (p < 0.001) during the interim period and after reimplantation.

CONCLUSION

Static spacers are being utilised in significantly more complex and unfavourable preoperative scenarios. Therefore, a preoperative selection bias may be at least partially accountable for any disparities observed in postoperative outcomes. To achieve the best possible results, surgeons should know and respect the distinct indications of static and articulating spacers and consequently understand and use them as complementary surgical options.

LEVEL OF EVIDENCE

Level III.

Efficacy of EDTA-NS irrigation in eradicating Staphylococcus aureus biofilm-associated infection

Aims

To investigate the efficacy of ethylenediaminetetraacetic acid-normal saline (EDTA-NS) in dispersing biofilms and reducing bacterial infections.

Methods

EDTA-NS solutions were irrigated at different durations (1, 5, 10, and 30 minutes) and concentrations (1, 2, 5, 10, and 50 mM) to disrupt Staphylococcus aureus biofilms on Matrigel-coated glass and two materials widely used in orthopaedic implants (Ti-6Al-4V and highly cross-linked polyethylene (HXLPE)). To assess the efficacy of biofilm dispersion, crystal violet staining biofilm assay and colony counting after sonification and culturing were performed. The results were further confirmed and visualized by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). We then investigated the efficacies of EDTA-NS irrigation in vivo in rat and pig models of biofilm-associated infection.

Results

When 10 mM or higher EDTA-NS concentrations were used for ten minutes, over 99% of S. aureus biofilm formed on all three types of materials was eradicated in terms of absorbance measured at 595 nm and colony-forming units (CFUs) after culturing. Consistently, SEM and CSLM scanning demonstrated that less adherence of S. aureus could be observed on all three types of materials after 10 mM EDTA-NS irrigation for ten minutes. In the rat model, compared with NS irrigation combined with rifampin (Ti-6Al-4V wire-implanted rats: 60% bacteria survived; HXLPE particle-implanted rats: 63.3% bacteria survived), EDTA-NS irrigation combined with rifampin produced the highest removal rate (Ti-6Al-4V wire-implanted rats: 3.33% bacteria survived; HXLPE particle-implanted rats: 6.67% bacteria survived). In the pig model, compared with NS irrigation combined with rifampin (Ti-6Al-4V plates: 75% bacteria survived; HXLPE bearings: 87.5% bacteria survived), we observed a similar level of biofilm disruption on Ti-6Al-4V plates (25% bacteria survived) and HXLPE bearings (37.5% bacteria survived) after EDTA-NS irrigation combined with rifampin. The in vivo study revealed that the biomass of S. aureus biofilm was significantly reduced when treated with rifampin following irrigation and debridement, as indicated by both the biofilm bacterial burden and crystal violet staining. EDTA-NS irrigation (10 mM/10 min) combined with rifampin effectively removes S. aureus biofilm-associated infections both in vitro and in vivo.

Conclusion

EDTA-NS irrigation with or without antibiotics is effective in eradicating S. aureus biofilm-associated infection both ex and in vivo.

Enhanced antibiotic release from bone cement spacers utilizing dual antibiotic loading with elevated vancomycin concentrations in two-stage revision for periprosthetic joint infection

PURPOSE

Antibiotic loaded bone cement spacers provide high local antibiotic concentrations, preserve bone stock, and reduce soft tissue contractions. The objective of this in-vitro study was to compare antibiotic release from spacers, aiming to discover the most optimal preparation and identify modifiable factors that can further enhance antibiotic release.

METHODS

Six distinct spacer preparation were created using three different bone cements and manual incorporation of antibiotics. During a six-week period, the release of antibiotics from each spacer was measured individually at ten predetermined time points using a chemiluminescent immunoassay.

RESULTS

Manually adding 4 g of vancomycin to every 40 g of "Palacos R + G" yielded the most favorable release profile. Throughout all preparations, antibiotic release consistently and significantly decreased over the six-week period. When incorporating a higher concentration of vancomycin, a significantly higher cumulative release of vancomycin was observed, with varying effects on the release of gentamicin. The choice of bone cement had a significant impact on antibiotic release.

CONCLUSION

To enhance antibiotic release from spacers, surgeons should manually incorporate high antibiotic concentrations into the most appropriate bone cement and keep the interim period as short as possible. Specifically, we suggest manual incorporation of 4 g of vancomycin to every 40 g of gentamicin premixed "Palacos R + G" to create bone cement spacers.

Analysis of the clinical efficacy of two-stage revision surgery in the treatment of periprosthetic joint infection in the knee: A retrospective study

BACKGROUND

Periprosthetic joint infection (PJI) is a catastrophic complication that can occur following total knee arthroplasty (TKA). Currently, the treatment for PJI mainly includes the use of antibiotics alone, prosthetic debridement lavage, primary revision, secondary revision, joint fusion, amputation, etc.

AIM

To explore the clinical effect of two-stage revision surgery for the treatment of PJI after TKA.

METHODS

The clinical data of 27 patients (3 males and 24 females; age range, 47–80 years; mean age, 66.7 ± 8.0 years; 27 knees) with PJI treated with two-stage revision surgery in our hospital between January 1, 2010 and December 31, 2020 were analyzed retrospectively. The following outcomes were compared for changes between preoperative and last follow-up results: Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), visual analogue scale (VAS) scores, Hospital for Special Surgery (HSS) scores, knee range of motion (ROM), and infection cure rates.

RESULTS

All 27 patients were followed up (range, 13–112 mo). The ESR (14.5 ± 6.3 mm/h) and CRP (0.6 ± 0.4 mg/dL) of the patients at the last follow-up were significantly lower than those at admission; the difference was statistically significant (P < 0.001). The postoperative VAS score (1.1 ± 0.7), HSS score (82.3 ± 7.1), and knee ROM (108.0° ± 19.7°) were significantly improved compared with those before the surgery; the difference was statistically significant (P < 0.001). Of the 27 patients, 26 were cured of the infection, whereas 1 case had an infection recurrence; the infection control rate was 96.3%.

CONCLUSION

Two-stage revision surgery can effectively relieve pain, control infection, and retain good joint function in the treatment of PJI after TKA.

Mechanical strength of antibiotic-loaded PMMA spacers in two-stage revision surgery

Background

Antibiotic-loaded polymethylmethacrylate (PMMA) bone cement spacers provide high local antibiotic concentrations and patient mobility during the interim period of two-stage revision for periprosthetic joint infection (PJI). This study compares mechanical characteristics of six dual antibiotic-loaded bone cement (dALBC) preparations made from three different PMMA bone cements. The study`s main objective was to determine the effect of time and antibiotic concentration on mechanical strength of dALBCs frequently used for spacer fabrication in the setting of two-stage revision for PJI.

Methods

A total of 84 dual antibiotic-loaded bone cement specimens made of either Copal spacem, Copal G + V or Palacos R + G were fabricated. Each specimen contained 0.5 g of gentamicin and either 2 g (low concentration) or 4 g (high concentration) of vancomycin powder per 40 g bone cement. The bending strength was determined at two different timepoints, 24 h and six weeks after spacer fabrication, using the four-point bending test.

Results

Preparations made from Copal G + V showed the highest bending strength after incubation for 24 h with a mean of 57.6 ± 1.2 MPa (low concentration) and 50.4 ± 4.4 MPa (high concentration). After incubation for six weeks the bending strength had decreased in all six preparations and Palacos R + G showed the highest bending strength in the high concentration group (39.4 ± 1.6 MPa). All low concentration preparations showed superior mechanical strength compared to their high concentration (4 g of vancomycin) counterpart. This difference was statistically significant for Copal spacem and Copal G + V (both p < 0.001), but not for Palacos R + G (p = 0.09).

Conclusions

This study suggests that mechanical strength of antibiotic-loaded PMMA bone cement critically decreases even over the short time period of six weeks, which is the recommended interim period in the setting of two-stage revision. This potentially results in an increased risk for PMMA spacer fracture at the end of the interim period and especially in patients with prolonged interim periods. Finally, we conclude that intraoperative addition of 4 g of vancomycin powder per 40 g of gentamicin-premixed Palacos R + G (Group D) is mechanically the preparation of choice if a dual antibiotic-loaded bone cement spacer with high antibiotic concentrations and good stability is warranted. In any case the written and signed informed consent including the off-label use of custom-made antibiotic-loaded PMMA bone cement spacers must be obtained before surgery.

Two-Stage Exchange Using a Short Intramedullary Nail for Treatment of Periprosthetic Knee Infections: A Technique Worth Questioning

Periprosthetic joint infections (PJIs) following total knee arthroplasty (TKA) are serious orthopaedic complications that pose marked burdens to both patients and health care systems. At our institution, two-stage exchange with a temporary short antibiotic cement-coated intramedullary nail was utilized for the treatment of repeat PJIs in a series of compromised patients with considerable bone loss. This study reports on (1) success rates, (2) functional and pain outcomes, (3) and complications for patients receiving a temporary short intramedullary nail for the treatment of PJI. Our institutional database was queried for all repeat knee PJI patients between March 1st, 2009 and February 28th, 2015. Patients with type II/III Anderson Orthopaedic Research Institute (AORI) bone defects who underwent two-stage exchange arthroplasty with a short antibiotic-coated intramedullary nail were included for analysis (n = 31). Treatment success was determined using the Delphi-based consensus definition of a successfully treated PJI: infection eradication (healed wound with no recurrence of infection by the same organism), no further surgical intervention for infection after reimplantation, and no PJI-related mortality. A paired t-test was performed to assess for continuous variables. A total of 26 patients went on to reimplantation, while 5 patients retained the intramedullary nail. Overall treatment success was 74.2%. Range of motion significantly decreased postoperatively (102.1 vs. 87.3 degrees; p < 0.001), while Knee Society Scores (function) significantly increased (55.6 vs. 77.7, p < 0.001). A majority of patients were full weight-bearing immediately following surgery (38.7%). Treating poor health status patients with PJI of the knee can be difficult after multiple revisions. With a success rate similar to conventional methods, our results demonstrate that two-stage exchange with a temporary short intramedullary nail may be a desirable treatment option for patients with bony defects wishing to avoid amputation or permanent arthrodesis. However, this method does not outperform other treatment modalities, and may not be suitable for all patients. Patient expectations and health status should be carefully assessed to determine if this procedure is appropriate in this complex patient population.

Hip Spacers with a Metal-on-Cement Articulation Did Not Show Significant Surface Alterations of the Metal Femoral Head in Two-Stage Revision for Periprosthetic Joint Infection

Two-stage revision is considered the gold standard treatment for chronic periprosthetic joint infection (PJI). During the interim period, between explantation of the infected hip endoprosthesis and revision arthroplasty, individually formed articulating hip spacers made of polymethylmethacrylate (PMMA) bone cement can be used to provide better soft tissue preservation, local antibiotic release, and improved postoperative mobilization. If effective prevention from luxation is achieved, hip function and hence overall patient satisfaction is improved. Zirconium oxide particles inside conventional PMMA bone cement, however, are known to enhance third-body wear, which may cause alterations of the metal head in the articulating spacer and hence become a serious risk for the patient. Therefore, the aim of our study was to analyze whether the articular surface of cobalt-chrome (CoCr) femoral heads is significantly altered in the setting of a metal-on-cement articulation during the interim period of two-stage revision for PJI. We analyzed a consecutive series of 23 spacer cases and compared them with femoral heads from two series of conventional hip arthroplasty revisions with metal-on-polyethylene articulations and different time intervals in situ. To investigate metallic wear, the femoral heads were thoroughly examined, and their surface roughness was measured and analyzed. We found no significant differences between the two conventional hip arthroplasty groups, despite their very different times in situ. Furthermore, the individually different times in situ within the spacer group had no significant impact on surface roughness, either. Compared with the spacer group, the surface roughness of the metal femoral heads from both conventional hip arthroplasty groups were even higher. Within the spacer group, roughness parameters did not show significant differences regarding the five predefined locations on the metal head. We conclude that metal-on-cement articulations do not cause enhanced surface alterations of the metal femoral head and hence do not limit the application in articulating hip spacers in the setting of two-stage revision for PJI.

Two-Stage Treatment for Total Knee Arthroplasty Infection Utilizing an Articulating Prefabricated Antibiotic Spacer

Periprosthetic joint infection represents a serious complication following total knee arthroplasty. In the setting of chronic or age-indeterminate total knee arthroplasty infection, a 2-staged approach has been traditionally the preferred method of treatment over single-stage debridement and reimplantation debridement or debridement, antibiotics and implant retention. Two-stage is the preferred treatment method in North America and has demonstrated better overall success than the single stage techniques. Additionally, the 2-stage method is the preferred treatment for difficult to treat pathogens as well as in patients who have already undergone a previous revision procedure. An articulating prefabricated antibiotic spacer has entered the armamentarium of 2-stage revision knee surgery, and has demonstrated comparable results to custom and static spacers in terms of the primary goal of infection control. Importantly, the potential for enhanced mobility and function hold promise by safely providing a more "livable" knee during the convalescent period prior to definitive reimplantation.

Antibiotic-impregnated articulating cement spacer maintained for 7 years in situ for two-stage primary total knee arthroplasty: a case report

Background

Antibiotic-impregnated articulating cement spacers can maintain interim joint motion with the potential to enhance functional status and improve patient satisfaction. Articular surfaces with cement against cement have raised concerns regarding mechanical complications and cement debris during knee motion. However, long-term clinical conditions regarding these concerns are not well addressed.

Case presentation

We report a case in which articulating cement spacers were maintained in situ for 7 years. The patient had severe left knee pain with an ankylosing knee and severe tricompartmental arthritis due to tuberculous infection. We planned to perform one- or two-stage primary total knee arthroplasty (TKA), depending on the presence of infection. Persistent osteomyelitis was found intraoperatively. The second-stage TKA was delayed on the patient’s request. As the patient was satisfied with the improved knee function and pain relief after using articulating cement spacers. No symptom or sign that suggested recurrent infection or systemic toxicity was found during the 7-year follow-up. However, it seemed that the bone loss progressed insidiously. At the 7-year follow-up, a broken articulating cement spacer and medial femoral condylar fracture were found. The second-stage TKA was performed, and a considerable amount of bone loss surrounded by dense granulation tissue was observed intraoperatively. Excisional biopsy of the tissue revealed chronic foreign body reaction with infiltration of giant cells and macrophages.

Conclusion

Although the articular spacers were maintained for 7 years without major complications, regular observation of the development and progress of bone loss was required. Surgeons should take considerable bone loss into account during conversion TKA in patients with a prolonged retention of articulating cement spacers.

Cement Pedestal Spacer Technique for Infected Two-stage Revision Knee Arthroplasty: Description and Comparison of Complications

BACKGROUND

Infection following total knee arthroplasty (TKA) is a significant complication, with an incidence of up to 2% in primary TKA and 4%-8% in revision cases. Two-stage revision is the gold standard treatment for long-lasting infections of TKA. The purpose of this study was to describe the cement pedestal spacer technique used in infected two-stage revision knee arthroplasty and compare complications against conventional fixed and mobile cement spacers.

PATIENTS AND METHODS

A retrospective review was conducted in all cases who underwent two-stage TKA revision for infection between 2009 and 2015. These cases were separated into groups depending on the cement spacer utilized (fixed, mobile nonpedestal, and mobile spacers with cement pedestal). The cement pedestal technique involves press fitting a cement cylinder into the femur before definitive spacer insertion.

RESULTS

Forty four patients underwent two-stage revision TKA. Fewest complications were observed in the pedestal group, with no spacers having subluxed/tilted. The longest followup was also observed in the pedestal group (mean 52.5 months). Mobile spacers with no cement pedestal displayed the highest reinfection rate (16.7%) and the greatest number of cases with complications (malalignment, subluxation, tilting, and spacer fracture). All patients in the pedestal group were ambulatory after the first-stage revision.

CONCLUSIONS

The cement pedestal technique minimizes complications by optimizing component positioning and balancing. It also safely extends the indication for an articulated spacer into a set of cases with more extensive bone loss and allows for extended monitoring of inflammatory markers.

What Markers Best Guide the Timing of Reimplantation in Two-stage Exchange Arthroplasty for PJI? A Systematic Review and Meta-analysis

BACKGROUND

There is no consensus on the appropriate marker to use when deciding to perform reimplantation after two-stage exchange arthroplasty for periprosthetic joint infection (PJI).

QUESTIONS/PURPOSES

What tests provide acceptable diagnostic value to guide appropriate timing of reimplantation in two-stage exchange arthroplasty for PJI?

METHODS

A search of online databases (MEDLINE, EMBASE, OVID, and Cochrane database) was performed containing articles that provided sensitivity and specificity values for accuracy for predicting reimplantation of the hip and/or knee. Twelve articles were included for final analysis, which included data from 1047 patients. Data that described the diagnostic accuracy of markers for reimplantation were evaluated and categorized into four main entities according to diagnostic method (serologic, synovial, tissue, and diagnostic imaging). Twelve parameters were examined, including serum erythrocyte sedimentation (ESR) rate, serum C-reactive protein (CRP), serum white blood cell (WBC) count, synovial fluid Gram stain, synovial fluid culture, synovial fluid sonication culture, synovial fluid WBC, synovial fluid polymorphonucleocyte percentage (PMN%), tissue Gram stain, tissue culture, positron emission tomography scan, and leukocyte scan. Each of the included articles was independently analyzed for risk of bias and applicability by using QUADAS-2. Statistical heterogeneity was calculated by using the Cochran Q test, and an α of 0.10 was considered significant for heterogeneity.

RESULTS

Tissue culture (sensitivity 0.82 [0.72-0.90], specificity 0.91 [0.89-0.95], diagnostic odds ratio (DOR) 46.87 [95% confidence interval {CI}, 22.03-99.69], synovial fluid PMN% (sensitivity 0.77 [0.46-0.95], specificity 0.74 [0.67-0.81], DOR 11.27 [95% CI, 2.89-43.61]), and synovial fluid culture (sensitivity 0.64 [0.52-0.74], specificity 0.96 [0.93-0.98], DOR 27.07 [95% CI, 2.55-288.00]) showed relatively high diagnostic performance. Other parameters had poorer diagnostic accuracy: ESR (sensitivity 0.56 [0.40-0.72], specificity 0.60 [0.53-0.66], DOR 2.41 [95% CI, 0.60-9.72), CRP (sensitivity 0.53 [0.39-0.67], specificity 0.72 [0.66-0.78], DOR 2.25 [95% CI, 0.09-4.63), and synovial fluid WBC count (sensitivity 0.37 [0.19-0.58], specificity 0.49 [0.41-0.57], DOR 0.94 [95% CI, 0.06-14.74). However, interpretation is limited, because only two to three studies were available for each pooled analysis. Both risks of bias and applicability concerns were low in the four domains assessed in QUADAS-2.

CONCLUSIONS

This meta-analysis suggests that no single marker was superior to all the others, and none (when used alone) is likely sufficient to confirm control of infection after the first stage of a two-stage protocol for PJI. Therefore, the current approach using multiple tools rather than a single marker is essential. Additionally, further studies must be conducted so that pooled analysis can be performed using multiple studies to determine ideal markers for reimplantation.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Removed antibiotic-impregnated cement spacers in two-stage revision joint arthroplasty do not show biofilm formation in vivo

Use of antibiotic-impregnated spacers is common in the two-stage approach to treatment of periprosthetic joint infection despite the lack of information regarding in vivo performance of these implants. Antibiotic elution levels likely often fall below the minimal inhibitory concentration need to inhibit bacterial growth, raising concern that the spacers themselves may provide a potential attachment site for biofilm formation. Advanced microscopy was used in this study to evaluate the surface characteristics of antibiotic-eluting spacers collected at the time of prosthesis reimplantation from 6 patients undergoing two-stage treatment for an infected total joint arthroplasty. Scanning electron microscopy and confocal scanning microscopy of the removed spacers revealed modest fibrous matrix formation and inflammatory cells with no biofilm or bacteria detected. This study supports the continued use of antibiotic spacers in the treatment of periprosthetic joint infection.

An intraoperatively moulded PMMA prostheses like spacer for two-stage revision of infected total knee arthroplasty

We report a series of 16 consecutive total knee arthroplasty (TKA) revision procedures for deep infection, treated with a newly developed intraoperatively moulded PMMA cement-prostheses-like spacer (CPLS). The standard treatment consisted of a two-stage protocol with initial explantation of the infected components combined with radical debridement, followed by implantation of a temporary cement spacer and final reimplantation of a new TKA. A sterilizeable Teflon tapered aluminium mould was developed for production of a custom made CPLS during the intervention. Stable implantation of the CPLS was achieved with a second cementation, allowing for correct alignment and ligament balancing. The spacer remained 3.5 months on average until reimplantation of a TKA occurred. At time of reimplantation, patients had an average KSS score of 84.44 points with an average flexion capacity of 102°. There was no recurrent infection during the study period of minimum 2 years. With this new technique, a low friction articulation with good stability, high comfort and a better range of motion compared to handcrafted spacers was achieved. The use of this spacer is a time sparing, cheap and convenient option in 2-stage TKA revision.

Durable infection control and function with the PROSTALAC spacer in two-stage revision for infected knee arthroplasty

BACKGROUND

A two-stage revision total knee arthroplasty is recognized as the gold standard in the treatment of infection. However, traditional spacers limit function in the interval between the two stages and may cause instability, scarring, and bone erosion. The PROSTALAC knee spacer is an antibiotic-loaded cement articulating spacer that allows some movement of the knee between stages. Whether motion enhances long-term function is unknown.

QUESTIONS/PURPOSES

We therefore identify the rate of control of infection using the PROSTALAC exchange spacer and to assess the clinical outcome after implantation with a definitive implant.

METHODS

We retrospectively reviewed 115 knees that underwent two-stage exchange with the PROSTALAC spacer. Forty-eight of these had a minimum followup of 5 years (mean, 9 years; range, 5-12 years).

RESULTS

At last review, 101 of the 115 knees (88%) had no evidence of infection. Of the 14 knees that became reinfected, four were from the same organism and 10 were with a different organism. After further intervention, using the two-stage approach again, the infection was controlled in 12 of the 14 initially reinfected cases, resulting in a failure to cure in only two cases. We observed improvements in mean WOMAC, Oxford, UCLA, and Patient Satisfaction scores at last review.

CONCLUSIONS

The PROSTALAC functional spacer was associated with a 98% rate of control of infection and improvements in the quality-of-life outcomes in the treatment of chronically infected total knee arthroplasties.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Biodegradable antibiotic delivery systems

Bacterial infection in orthopaedic surgery can be devastating, and is associated with significant morbidity and poor functional outcomes, which may be improved if high concentrations of antibiotics can be delivered locally over a prolonged period of time. The two most widely used methods of doing this involve antibiotic-loaded polymethylmethacrylate or collagen fleece. The former is not biodegradable and is a surface upon which secondary bacterial infection may occur. Consequently, it has to be removed once treatment has finished. The latter has been used successfully as an adjunct to systemic antibiotics, but cannot effect a sustained release that would allow it to be used on its own, thereby avoiding systemic toxicity.

This review explores the newer biodegradable carrier systems which are currently in the experimental phase of development and which may prove to be more effective in the treatment of osteomyelitis.

[Results of reimplantation for infected total knee arthroplasty: 107 cases]

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.

Pasteurella multocida infection of a total knee arthroplasty after a "dog lick"

The patient we report here underwent a total knee arthroplasty (TKA) which got infected with P. multocida after her dog had licked a small wound at the third toe of the same foot. Despite a correct treatment comprising synovectomy and cleansing, and an active antibiotic treatment for 3 months, the patient was readmitted for persistent infection of the same knee 2 weeks after the end of the antibiotic treatment. Sampling during surgery allowed for the growth of a P. multocida isolate proven by a molecular method to be identical to the previously isolated strain. This recurrent P. multocida infection was treated by a two-step change of the TKA comprising a 2-month period of antibiotic treatment between the two surgical interventions.

Hip and Knee Arthroplasty in the Geriatric Population

Osteoarthritis is the leading cause of hip and knee pathology in the geriatric population. Hip and knee arthroplasty are the definitive interventions to alleviate pain and restore physical functioning. Complications related to these procedures do occur: the most com-mon of these are infection, thromboembolism, dislocations, and periprosthetic fractures. New improvements related to minimally invasive and computer-assisted navigation surgery techniques are promising and already have shown excellent outcomes in patients exposed to joint arthroplasty.

Prosthetic joint infections

Success in the treatment of infected orthopedic prosthesis requires the best surgical approach in combination with prolonged optimum targeted antimicrobial therapy. In choosing the surgical option, one must consider the type of infection, condition of the bone stock and soft tissue, the virulence and antimicrobial susceptibility of the pathogen, the general health and projected longevity of the patient, and the experience of the surgeon. If surgery is not possible, an alternative is long-term oral antimicrobial suppression to maintain a functioning prosthesis. Treatment must be individualized for a specific infection in a specific patient.