Knee Spacer Research Articles

The effectiveness of antibiotic-loaded bone cement for preventing postoperative infection in patients undergoing total knee arthroplasty

The study question focuses on the effectiveness of antibiotic-loaded bone cement (ALBC) for preventing postoperative infection in patients undergoing total knee arthroplasty (TKA). Infection has remained being a rare but serious complication after TKA. However, the utilization of ALBC for reducing the occurrence of infection is debated. We used the National Inpatient Database, which was provided by National Health Research Institutes. We included 16,108 TKA adult patients between January and November, 2012. There were 5,605 patients (34.8%) using ALBC. The postoperative 30-day infection and acute kidney failure were compared. We adopted multi-level logistic regression models to regulate for potential confounding factors considerately of hospital levels (including medical centers, metropolitam hospitals, and native communitiy hospitals). The odds ratio (OR) of the infection in ALBC use group and 95% confidence interval (CI) were estimated. The main compositions of ALBC are vancomycin (71.7%), followed by gentamicin (30.7%), and cefuroxime (12.4%). Among patients with ALBC use, 83.8% patient had one sort of antibiotics, nevertheless 16.0% patients had two combided antibiotics. We found that the utilization of ALBC couldn't reduce the postoperative 30-day infection. When conducting multilevel logistic regression model, there remained no favorable effect of ALBC in reducing postopeartive infection (OR= 0.80, 95% CI: 0.50-1.26, p= 0.329). For risk of acute kidney failure for ALBC users, the sample size (n=7) is just too small to evaluate. In conclusion, there was no significant advantage of ALBC in reducing postoperative 30-day infection in patients undergoing TKA. During the past 20 years, antibiotic-loaded hip and knee spacers became a well-liked method of managing such infections with reported success rates of > 90% 2- 3. Complications are rather infrequent and consist mostly of mechanical (spacer fracture, dislocation, bone fracture) and people associated with the antibiotic impregnation of bone cement (reinfection/infection persistence, systemic side effects such as renal or hepatic failure, allergic reactions). The release of the antibiotic from the cement is influenced by the type (viscosity) of the cement, by the surface of contact/exchange, by the conditions of the compound, and the type and amount of antibiotic. The antibiotic is released from the surface of the cement and from cracks and voids in the cement itself. The nature of the polymer allows the passage of fluids, allowing the discharge of the incorporated antibiotic. Nevertheless, while the hydrophobicity of the cement limits this release at less than the 10%, most of the antibiotic is released within the first hours and days after surgery. In addition, a significant amount should be trapped in cement for a while. At the time of the preparation, when mixed, it becomes a viscous material paste, which solidifies very quickly by an exothermic reaction. It acts as a fixation between the prosthetic components and the cancellous bone. During the mixing, pores of various sizes are produced as consequence of the reaction and volume variations. These microholes may represent the beginning point of cracks and thus are often responsible of the premature failure of the cement. To avoid the formation of those pores, it's possible to organize the cement under vacuum conditions.

Postural Stability after Unicondylar Knee Arthroplasty and Patient-Specific Interpositional Knee Spacer.

Purpose and Hypothesis. Knee osteoarthritis results, inter alia, in decreased postural stability. After arthroplasty, postural stability recovers, but it is unclear whether this can be ascribed to a reduction of pain or to the preserving of receptor-rich intraarticular soft tissue and natural knee kinematics. The objective of this study was to evaluate whether an unicondylar knee arthroplasty provides better results regarding postural stability or a patient-specific knee spacer. Methods. In this comparative study, we assessed functional results and postural stability 16 months after 20 unicondylar knee arthroplasties (group A) and 20 patient-specific interpositional knee device implantations (group B). Patients were evaluated using the KSS and WOMAC score. Postural stability was analysed during single leg stance on a force platform (Biodex Balance System). Results. Concerning postural stability, range of motion (ROM), and KSS 16 months after the procedure, there were no significant differences between both groups. Conclusion. Successful treatment of knee osteoarthritis restores postural stability to the level of the contralateral side, regardless of the implant device.

Shape memory alloy smart knee spacer to enhance knee functionality: model design and finite element analysis.

In this paper we introduce Shape Memory Alloy (SMA) for designing the tibial part of Total Knee Arthroplasty (TKA) by exploiting the shape-memory and pseudo-elasticity property of the SMA (e.g. NiTi). This would eliminate the drawbacks of the state-of-the art PMMA based knee-spacer including fracture, sustainability, dislocation, tilting, translation and subluxation for tackling the Osteoarthritis especially for the aged people of 45-plus or the athletes. In this paper a Computer Aided Design (CAD) model using SolidWorks for the knee-spacer is presented based on the proposed SMA adopting the state-of-the art industry-standard geometry that is used in the PMMA based spacer design. Subsequently Ansys based Finite Element Analysis is carried out to measure and compare the performance between the proposed SMA based model with the state-of-the art PMMA ones. 81% more bending is noticed in the PMMA based spacer compared to the proposed SMA that would eventually cause fracture and tilting or translation of spacer. Permanent shape deformation of approximately 58.75% in PMMA based spacer is observed compared to recoverable 11% deformation in SMA when same load is applied on both separately.

Treatment of infected nonunion total knee arthroplasty periprosthetic fracture using a stemmed articulating spacer

BackgroundWe present a case of multifocal infection involving the left total hip replacement and the right total knee replacement of a patient, further complicated by an infected non-union of a periprosthetic fracture of the right knee. This required the unique simultaneous management of both infection eradication and fracture stabilization in the knee. MethodsBoth sites were treated with a two-stages procedure, including the novel use of a stemmed articulating spacer for the right knee. This spacer was made combining a retrograde humeral nail, coated with antibiotic-impregnated cement, and a pre-formed articulating cement spacer. The patient was able to weight-bear on this spacer. ResultsThe fracture went on to unite, and a second stage was performed with the use of stemmed prosthesis and augments. She remains infection free two years after the second stage operation. ConclusionsThe use of a stemmed articulating knee spacer can facilitate infection eradication and fracture stabilization while preserving some motion and weight-bearing ability in the two-stages management of an infected periprosthetic fracture of the knee. Level of evidenceLevel V (Case report).

Confirming Sterility of an Autoclaved Infected Femoral Component for Use in an Articulated Antibiotic Knee Spacer: A Pilot Study

Antibiotic spacer designs have proven effective at eradicating infection during a two-stage revision arthroplasty. Temporary reuse of the steam-sterilized femoral component and a new all poly tibia component has been described as an effective articulating antibiotic spacer, but sterility concerns persist. Six explanted cobalt chrome femurs from patients with grossly infected TKA's and six stock femurs inoculated with different bacterial species were confirmed to be bacteria-free after autoclaving under a standard gravity-displacement cycle. The effect of steam sterilization on cobalt chrome fragments contaminated with MRSA biofilm was analyzed microscopically to quantify remaining biofilm. The autoclave significantly reduced the biofilm burden on the cobalt chrome fragments. This study confirmed sterility of the femur after a standard gravity–displacement cycle (132°C, 27 PSIG, 10minutes).

Does knee revision after an articulated spacer implant provide normal gait restoration?

The aim of this study was to quantitatively evaluate gait parameters in patients who underwent a revision procedure after an interval articulated spacer for septic knee prosthesis. Ten adult subjects underwent three-dimensional computerized gait analysis 12 months after second-stage knee revision procedure. Kinematic and kinetic parameters were acquired and compared with a normal reference population. Data were also compared with those collected in a previous study, in which the same cohort of patients underwent gait analysis 8-14 weeks after spacer implantation. Kinematic and kinetic parameters did not show any significant difference between the affected and unaffected limb. Compared to normal reference population, patients treated with revision knee prosthesis showed a reduced mean gait velocity, step frequency, stride and step length, average knee range of motion, knee power and ground reaction forces. When comparing average data with those observed after spacer implant, no difference was observed in kinematic variables, while kinetic analysis demonstrated a significant improvement in knee power. This study shows that 1 year after second-stage knee revision surgery, kinematic and kinetic values remain lower than those observed in a normal reference population. Only slight improvements in walking ability are shown, when analysing data in comparison with those collected after a preformed articulated knee spacer. This finding points out the long time to full functional recovery after knee revision surgery and the limited improvement of gait when compared to the one achieved at the time of spacer implant.

Comparative Study of Knee Balancer and Spacer Block for Gap Measurement in Total Knee Arthroplasty

Comparative Study of Knee Balancer and Spacer Block for Gap Measurement in Total Knee Arthroplasty

Detectable Serum Tobramycin Levels in Patients With Renal Dysfunction and Recent Placement of Antibiotic-Impregnated Cement Knee or Hip Spacers

To the Editor—The placement of an antibiotic-impregnated cement spacer (ACS) during a staged replacement of an infected prosthetic joint is frequently used to increase antibiotic concentration in the joint capsule, and the 2012 Infectious Diseases Society of America Clinical Practice Guidelines for management of prosthetic joint infections state that systemic toxicity from antibiotic-impregnated cement rarely occurs [1]. However, a recent retrospective study found that higher doses of tobramycin in the spacer cement were associated with increased risk of acute kidney injury (AKI) [2–4]. An estimated 1%–2% of the >725 000 total knee and hip arthroplasties performed yearly in United States hospitals become infected over the duration of use [5, 6]; therefore, complications from ACSs could be an important source of postoperative morbidity. A patient developed renal insufficiency after receiving a tobramycin-containing ACS and was found to have a serum tobramycin level of 19.8 µg/mL shortly after surgery and a level of 3.0 µg/mL 4 weeks later with no systemic aminoglycoside administration. To investigate this further, we identified patients with postoperative AKI and detectable serum tobramycin levels after receiving an ACS during 2-stage arthroplasty revision. Between February 2011 and April 2012, physicians on the inpatient infectious diseases consultation service were asked to measure serum tobramycin concentrations in patients with a >50% rise in serum creatinine from the preoperative baseline following placement of a tobramycin-containing ACS. Approval for this study was obtained from the Vanderbilt Institutional Review Board. Ten patients were identified with an acute rise in serum creatinine and a detectable serum tobramycin level following placement of a tobramycin-containing ACS out of total of 46 revision arthroplasties with ACS placement performed at our institution during this period (Table ​(Table1).1). Patients ranged in age from 50 to 83 years and 6 were male. All patients had comorbid conditions that could predispose to postoperative renal dysfunction as well as perioperative interventions that may have increased the risk of renal dysfunction (Table ​(Table1).1). All patients also received concomitant oral or parenteral antibiotics, but none received systemic aminoglycosides. Table 1. Patient Characteristics, Serum Tobramycin Level, and Postoperative Creatinine Change All ACSs contained tobramycin (mean dose, 8.2 g), and 9 of 10 also contained vancomycin (mean dose, 7.6 g). The average postoperative increase was 260% of the baseline creatinine and occurred early in the postoperative course (range, postoperative day 1–11). All patients tested had detectable serum tobramycin (mean level, 3.3 µg/mL [range, 0.1–19.8 µg/mL]). Of the 9 patients with subsequent laboratory values, serum creatinine levels normalized after an average of 15.9 days postoperatively (range, 10–26 days). The data provide evidence of systemic tobramycin absorption from ACSs placed during revision joint arthroplasty. This finding suggests that patients receiving an ACS may have prolonged exposure to elevated serum aminoglycoside levels, which could increase the risk of toxicity, including nephrotoxicity. Prospective studies are warranted to determine the true incidence of systemic aminoglycoside absorption from ACSs and the operative and patient risk factors that lead to nephrotoxicity.

Two-stage treatment of infected total knee arthroplasty: two to thirteen year experience using an articulating preformed spacer

Infection following knee replacement is an important cause of failure despite rigorous prophylaxis antibiotic protocols. The two-stage reimplantation procedure is considered the gold standard for treatment of subacute and chronic deep periprosthetic infections. The purpose of this study was to determine whether or not a preformed articulated spacer would allow comparable eradication of infection equal to rates reported in published studies and to see whether there is a resulting improvement in postoperative function with an acceptable quality of life, reducing postoperative pain and limiting surgical complications, thus simplifying the second stage of the procedure. We retrospectively reviewed 50 patients with infected TKA who underwent a two-stage exchange arthroplasty using an articulating preformed spacer. The device, designed like an ultracongruent condylar knee prosthesis, is composed of acrylic cement impregnated with antibiotic, with tested and standardised mechanical properties and antibiotic content and release mechanism. The median follow-up period was seven (two to 13) years. Two-stage exchange arthroplasty was successful in controlling the infection in 92% of patients; 64% of patients where women, and median patient age was 68 (54-80) years. Median implantation time of the preformed spacer was 16 (four to 60) weeks; 4% of infections were delayed, and 96% were late. Forty-six percent were caused by coagulase-negative Staphylococcus (CoNS). Mean Knee Society Score (KSS) was 35.38 (clinical) and 37.96 (function) on presentation; it improved to a mean of 72.92 (clinical) and 76.04 (function) after the first stage and to a mean of 75.38 (clinical) and 80.58 (function) at the final review. Bone loss was unchanged between stages, and range of motion remained unchanged or improved after definitive reimplantation. The use of preformed articulated knee spacer during a two stage technique for infected TKA improves patient QOL between stages and increases patient compliance and cooperation, reducing social costs.

One‐stage Versus Two‐stage Exchange

Liaison: Paul Lichstein MD, MSLeaders: Thorsten Gehrke MD (International), Adolph Lombardi MD, FACS (US), Carlo RomanoMD (International), Ian Stockley MB, ChB, MD, FRCS (International)Delegates: George Babis MD, Jerzy Bialecki MD, La´szlo´ Bucsi MD, Xu Cai MD, Li Cao MD, Briande Beaubien MD, Johannes Erhardt MD, Stuart Goodman MD, PhD, FRCSC, FACS, FBSE,William Jiranek MD, Peter Keogh, David Lewallen MD, MS, Paul Manner MD, WojciechMarczynski MD, J. Bohannon Mason MD, Kevin Mulhall MB, MCh, FRCSI, Wayne PaproskyMD, Preetesh Patel MD, Francisco Piccaluga MD, Gregory Polkowski MD, Luis Pulido MD, IanStockley MBBS, ChB, FRCS, Juan Suarez MD, Fritz Thorey MD, Rashid Tikhilov MD, JobDiego Velazquez MD, Heinz Winkler MD

Comment on: Two-stage revision of septic knee prosthesis with articulating knee spacers yields better infection eradication rate than one-stage or two-stage revision with static spacers

We have read the recent article by Dr. Romano et al. [6] with great interest. The number of periprosthetic infections associated with hip and knee arthroplasties is increasing worldwide. In addition to the clinical problems they present, the financial burden of each case is high and the socioeconomic costs are increasing each year. The current standard treatment options for eradicating such infections are oneand twostage exchanges. The literature overview seems to be biased. The wellperformed review by Jamsen et al. [4] failed to show a difference between the oneand two-stage approaches. Romano et al. conclude that better eradication rates may be achieved by a two-stage approach. We were wondering why the retrospective analysis by Mortazavi et al. [5] was not mentioned although it was online in the summer of 2011 and presented the previous year in a meeting. Mortazavi et al. concluded that there are currently no proper indicators that can guide orthopaedic surgeons in patient selection between a two-stage exchange and a reimplantation. Next, they observed that the failure rate after two-stage reimplantation for infected TKA is relatively high. There were no variables identified that would guide the surgeon to perform the second stage. It is therefore very surprising that 1 year later, another group is able to make a clear statement using a meta-analysis. Next, we would like to mention a recent published article by Singer et al. [7]. They stated that the rate of infection control for one-stage revision of infected knee arthroplasties is still unclear according to the literature. For their series, they observed an infection control rate of 95 % for one-stage protheses and higher knee scores were reported than for two-stage revisions. This contrasts greatly with Dr. Romano et al.’s study. The worst series in the article by Romano et al. comes from our own institution by von Foerster et al. [8]. These patients were treated around 1980. Algorithms regarding topical antibiotic choice have improved in the last three decades, and although they are still missing in the literature, we currently observe better outcomes. This study is the only outlier in their overview and seems to present misleading results and conclusions. The combination of germ-specific systemic and topical antibiotic therapy is the key to success. Recent publications identified much higher infection control rates for the one-stage approach to septic THA exchanges [1, 2]. Such actual data are missing for septic TKA exchanges. As one of the biggest centres for revision arthoplasties in the world, we prefer a one-stage approach in septic TKA surgery because it is well documented that one-stage surgery is associated with less stress for the patient, fewer complications, better surgical conditions and better functional results [3]. There is currently a strong trend favouring one-stage approaches. However, we have to state that valid literature data are still missing and that this review misleads the reader. This comment refers to the article available at doi:10.1007/s00167-012-1885-x.

The Use of Preformed Articulating Knee Spacers in Two-Stage Revision Arthroplasty for Periprosthetic Infection

The Use of Preformed Articulating Knee Spacers in Two-Stage Revision Arthroplasty for Periprosthetic Infection

Intramedullary knee spacer in 2-stage revision knee surgery with segmental bone loss

In 2-stage revision knee surgery ending with a tumor prosthesis, the bone loss is so large that in the interim period the patient can be treated with (1) rest in bed with or without skeletal traction, (2) external fixation, or (3) a custom-made spacer. Apart from the technical challenge of eradicating these infections, the stabilization of the knee and preservation of leg length until reimplantation can be a problem. We present our early experience with a new type of knee spacer for patients with very large bone loss.

Do Dynamic Cement-on-Cement Knee Spacers Provide Better Function and Activity During Two-stage Exchange?

Implantation of an antibiotic bone cement spacer is used to treat infection of a TKA. Dynamic spacers fashioned with cement-on-cement articulating surfaces potentially facilitate patient mobility and reduce bone loss as compared with their static counterparts, while consisting of a biomaterial not traditionally used for load-bearing articulations. However, their direct impact on patient mobility and wear damage while implanted remains poorly understood. We characterized patient activity, surface damage, and porous structure of dynamic cement-on-cement spacers. We collected 22 dynamic and 14 static knee antibiotic cement spacers at revision surgeries at times ranging from 0.5 to 13months from implantation. For these patients, we obtained demographic data and UCLA activity levels. We characterized surface damage using the Hood damage scoring method and used micro-CT analysis to observe the internal structure, cracking, and porosity of the cement. The average UCLA score was higher for patients with dynamic spacers than for patients with static spacers, with no differences in BMI or age. Burnishing was the only prevalent damage mode on all the bearing surfaces. Micro-CT analysis revealed the internal structure of the spacers was porous and highly inhomogeneous, including heterogeneous dispersion of radiopaque material and cavity defects. The average porosity was 8% (range, 1%-29%) and more than ½ of the spacers had pores greater than 1mm in diameter. Our observations suggest dynamic, cement-on-cement spacers allow for increased patient activity without catastrophic failure. Despite the antibiotic loading and internal structural inhomogeneity, burnishing was the only prevalent damage mode that could be consistently classified with no evidence of fracture or delamination. The porous structure of the spacers varied highly across the surfaces without influencing the material failure.

Preformed Articulating Knee Spacers in 2-Stage Total Knee Revision Arthroplasty: Minimum 2-Year Follow-Up

Two-stage revision arthroplasty using articulating spacers for the treatment of infected total knee arthroplasty (TKA) is a successful management technique. Our purpose was to report our results using preformed, commercially available articulating spacers made of gentamicin-impregnated cement. Thirty-three patients with infected primary or revision TKAs were treated with these spacers using a 2-stage revision technique. In most cases, the spacers were modified intraoperatively by adding a stem of reinforced antibiotic-impregnated acrylic cement. Successful eradication was achieved in 30 of 33 cases at a minimum 2-year follow-up interval. Two patients required a second spacer before successful revision TKA. No spacer fractures or dislocations occurred in this series. No adverse soft tissue effects were noted from the use of this type of articulating spacer.

Two-stage revision of septic knee prosthesis with articulating knee spacers yields better infection eradication rate than one-stage or two-stage revision with static spacers

The best method for treating chronic periprosthetic knee infection remains controversial. Randomized, comparative studies on treatment modalities are lacking. This systematic review of the literature compares the infection eradication rate after two-stage versus one-stage revision and static versus articulating spacers in two-stage procedures. We reviewed full-text papers and those with an abstract in English published from 1966 through 2011 that reported the success rate of infection eradication after one-stage or two-stage revision with two different types of spacers. In all, 6 original articles reporting the results after one-stage knee exchange arthoplasty (n = 204) and 38 papers reporting on two-stage revision (n = 1,421) were reviewed. The average success rate in the eradication of infection was 89.8% after a two-stage revision and 81.9% after a one-stage procedure at a mean follow-up of 44.7 and 40.7 months, respectively. The average infection eradication rate after a two-stage procedure was slightly, although significantly, higher when an articulating spacer rather than a static spacer was used (91.2 versus 87%). The methodological limitations of this study and the heterogeneous material in the studies reviewed notwithstanding, this systematic review shows that, on average, a two-stage procedure is associated with a higher rate of eradication of infection than one-stage revision for septic knee prosthesis and that articulating spacers are associated with a lower recurrence of infection than static spacers at a comparable mean duration of follow-up. IV.

Minimizing Dynamic Knee Spacer Complications in Infected Revision Arthroplasty

Deep infections are devastating complications of TKA often treated with component explantation, intravenous antibiotics, and antibiotic-impregnated cement spacers. Historically, the spacers have been static, which may limit patients' ROM and ability to walk. Several recent reports describe dynamic spacers, which may allow for improved ROM and make later reimplantation easier. However, because of several dynamic spacer problems noted at our institution, we wanted to assess their associated failures, reinfection rates, and functionality. We therefore asked whether there were differences between static and dynamic spacers in (1) reinfection rates, (2) complications directly related to the spacer, and (3) final patient functionality as measured by Knee Society objective scores and ROM. We retrospectively identified 111 patients (115 knees) with 34 dynamic spacers (30%) and 81 static spacers (70%). Reinfection rates, complications requiring additional surgery, and final Knee Society scores and ROM were collected for all patients. Reinfection rates were comparable between groups. In the dynamic spacer cohort, there were four complications; however, these could all be explained by surgical technical errors or patient weightbearing compliance. All patients with failed results eventually underwent successful two-stage exchange arthroplasty. Final Knee Society scores and ROM were also similar between groups. Reinfection rates, Knee Society scores, and ROM were comparable between the static and dynamic spacer groups. Meticulous surgical technique and proper patient selection should be used to avoid any complications with any spacers.

Does cyclical loading affect the elution of antibiotics from articulating cement knee spacers?

Two-stage revision surgery for infected total knee replacement offers the highest rate of success for the elimination of infection. The use of articulating antibiotic-laden cement spacers during the first stage to eradicate infection also allows protection of the soft tissues against excessive scarring and stiffness. We have investigated the effect of cyclical loading of cement spacers on the elution of antibiotics. Femoral and tibial spacers containing vancomycin at a constant concentration and tobramycin of varying concentrations were studied in vitro. The specimens were immersed and loaded cyclically to 250 N, with a flexion excursion of 45°, for 35 000 cycles. The buffered solution was sampled at set intervals and the antibiotic concentration was established so that the elution could be calculated. Unloaded samples were used as a control group for statistical comparison. The elution of tobramycin increased proportionately with its concentration in cement and was significantly higher at all sampling times from five minutes to 1680 minutes in loaded components compared with the control group (p = 0.021 and p = 0.003, respectively). A similar trend was observed with elution of vancomycin, but this failed to reach statistical significance at five, 1320 and 1560 minutes (p = 0.0508, p = 0.067 and p = 0.347, respectively). However, cyclically loaded and control components showed an increased elution of vancomycin with increasing tobramycin concentration in the specimens, despite all components having the same vancomycin concentration. The concentration of tobramycin influences both tobramycin and vancomycin elution from bone cement. Cyclical loading of the cement spacers enhanced the elution of vancomycin and tobramycin.

Gait analysis in patients with a preformed articulated knee spacer

Two-stage revision is one of the most widely accepted procedures to eradicate infection and restore function in infected knee prosthesis; while the use of an articulated spacers is advocated by many as a means to preserve function between stages, no data are available regarding gait parameters after spacer implant. The aim of present study was to assess and compare the gait parameters of patients with articulated knee spacers with a normal reference population and with the sound limb.Computerised gait analysis, was performed 8 to 14weeks after the infected knee prosthesis had been removed and a preformed, articulated, knee spacer had been implanted, in 10 consecutive patients.Kinematic data show a mean gait velocity reduction of 70% and a decrease of the range of motion of the operated knee of 59%, compared with controls. While ground reaction forces were only slightly reduced, frontal and sagittal moments and calculated powers around the affected knees were near zero or zero.Our findings point out the ability of a preformed articulated spacer to preserve, although reduced, the normal gait parameters and joint range of motion and the capacity of the human body to provide useful postural modifications, even in the absence of the proprioceptive input from a normal knee or from a traditional total knee replacement.

Predicting fatigue life of a PMMA based knee spacer using a multiaxial fatigue criterion

Experimental tests have played a major role in the assessment of fatigue endurance of orthopedic prostheses; however, cyclic tests on devices entail high costs. Here, a multiaxial fatigue criterion coupled with computational simulations and material properties measurements has been employed to predict fatigue life of the tibial component of a polymeric PMMA spacer. The ultimate aim is to obtain valid information on fatigue behavior avoiding fatigue tests on the device. First, an accurate measurement of the static and fatigue properties of PMMA samples is performed. Then, numeric simulations of the fatigue behavior of the PMMA spacer reproducing the experimental test conditions according to ISO 14879-1 were carried out in order to calculate the stress field throughout the device. Finally, a Risk Index was calculated by using a proper multiaxial fatigue criterion for brittle materials (Kakuno-Kawada) for the assessment of the device fatigue behavior by predicting the F-N curves. The numeric results were validated by comparing the predictions against experimental data already published by our group. The multiaxial fatigue criterion was able to predict the most critical point on the spacer upper surface and the fatigue behavior of the device that nicely matched the experimental curves. This approach represents a valuable tool to investigate the mechanical reliability of implantable devices; nevertheless, the use of advanced and specific failure criteria coupled with accurate data of the device’s material is mandatory to represent a real alternative to the experimental approach in fatigue life prediction.??Key words: Acrylic bone cement, Fatigue endurance, Finite element analyses, Knee spacer.