Mobile Spacers Research Articles

Selecting a high-dose antibiotic-laden cement knee spacer.

Prosthetic joint infection[PJI] after total knee arthroplasty (TKA) remains a common and challenging problem for joint replacement surgeons and patients. Once the diagnosis of PJI has been made, patient goals and characteristics as well as the infection timeline dictate treatment. Most commonly, this involves a two-stage procedure with the removal of all implants, debridement, and placement of a static or dynamic antibiotic spacer. Static spacers are commonly indicated for older, less healthy patients that would benefit from soft tissue rest after initial debridement. Mobile spacers are typically used in younger, healthier patients to improve quality of life and reduce soft-tissue contractures during antibiotic spacer treatment. Spacers are highly customizable with regard to antibiotic choice, cement variety, and spacer design, each with reported advantages, drawbacks, and indications that will be covered in this article. While no spacer is superior to any other, the modern arthroplasty surgeon must be familiar with the available modalities to optimize treatment for each patient. Here we propose a treatment algorithm to assist surgeons in deciding on treatment for PJI after TKA.

Simple and cost-effective way to make mobile antibiotic cement spacer: hand-made silicone mold

Background: Two-stage exchange arthroplasty is considered the most common approach for the management of prosthetic joint infections. There has been plentiful evidence to support the superiority of the mobile spacers over the static ones. Unfortunately, articulating options are not available in our low-resource environment, which motivated us to come up with an affordable way to create a mobile cement spacer. After experimenting with a variety of materials and producing methods, we realized that silicone is a favorable material for mold building and established a simple process of making a handmade silicone mold. We demonstrate the clinical outcomes of three prosthetic joint infections by using these spacers in the hope of spreading the idea to our colleagues who work in the circumstances of a developing country. Construction of the spacer molds: The molds, consisting of two parts, were shaped by using high viscosity addition silicone (elite HD+ putty soft, Zhermack SpA, Italy) as material, and previously removed implants as template. They were sterilized using ethylene oxide treatment before being ready for casting antibiotic-loaded bone cement spacer. Case report: Three cases of prosthetic infection were treated with two-stage revision, using antibiotic-impregnated cement spacer cast in hand-made silicone molds. We sought to determine intraoperative complications, postoperative range of motion, and functional scores. All the patients were regularly followed up to identify fractures or dislocation of the spacer, and reinfection. Results: At the end of the follow-up, all three patients had the infection eradicated. The three patients could sit comfortably with bent knees, walk with partial weight-bearing, and achieve 75–80 degrees of knee flexion in the first week after surgery. Follow-up X-rays revealed no fractures or dislocation in any of the spacers. Conclusion: Silicone molds offer a simple and cost-effective alternative to costly commercial products in producing articulating spacers. Treating infected joints arthroplasty with these spacers allows for early motion and partial weight bearing and improves patient satisfaction and life quality before reimplantation without significant complications.

Two-stage strategy in end-stage hip periprosthetic joint infection: utility of industrially prefabricated custom-made antibiotic spacers.

Use of prefabricated mobile spacers in end-stage cases of hip periprosthetic joint infection (HPJI) is hindered when large bone defects exist. In such cases, prefabricated custom-made antibiotic spacers (P-CMAS) offer an alternative. Such spacers are individually designed according to the size and anatomical characteristics of the bone defect. The purpose of this study is to describe and evaluate the use of such patient-specific spacers in a two-stage strategy to treat end-stage HPJI cases, and to report on clinical outcomes. A retrospective study identified all patients with end-stage HPJIs from January 2015 through December 2019, treated using a P-CMAS. Primary outcome: infection eradication rate. Secondary outcomes: spacer-related complications and patient satisfaction. Minimum follow-up: 12 months after the second-stage surgery. A total of 7 end-stage cases (mean of 6.7 previous surgical procedures) were included. Mean bone defect size was 191.57 (range 47-304) mm. Polymicrobial infection was detected in 42.86% of these cases. During the spacer stage there were no periprosthetic fractures, spacer dislocations or breakages, nor spacer-drug-related complications. All patients proceeded with the second stage uneventfully, with an average time between stages of 178 (range 119-326) days. In 5 cases a total femur arthroplasty was the reconstructive procedure performed. After a mean follow-up of 27.29 (range 14-49) months the infection was clinically eradicated in all patients, despite their difficult-to-treat scenarios. Industrially custom-made spacers offer an effective and safe option in performing 2-stage exchange arthroplasty in cases of end-stage HPJI with extensive bone defects.

Antibiotic Cement Spacers for Infected Total Knee Arthroplasties.

Periprosthetic infection remains a frequent complication after total knee arthroplasty. The most common treatment is a two-stage procedure involving removal of all implants and cement, thorough débridement, insertion of some type of antibiotic spacer, and a course of antibiotic therapy of varying lengths. After some interval, and presumed eradication of the infection, new arthroplasty components are implanted in the second procedure. These knee spacers may be static or mobile spacers, with the latter presumably providing improved function for the patient and greater ease of surgical reimplantation. Numerous types of antibiotic cement spacers are available, including premolded cement components, surgical molds for intraoperative spacer fabrication, and the use of new metal and polyethylene knee components; all these are implanted with surgeon-prepared high-dose antibiotic cement. As there are advantages and disadvantages of both static and the various mobile spacers, surgeons should be familiar with several techniques. There is inconclusive data on the superiority of any antibiotic spacer. Both mechanical complications and postoperative renal failure may be associated with high-dose antibiotic 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.

Antibiotic release and antibacterial efficacy in cement spacers and cement beads impregnated with different techniques: In vitro study.

This study aims to compare the antibiotic release and biological effectiveness of bead type and articulating spacers of different cement types with antibiotics added at alternative phases of cement preparation. Four gram vancomycin was added into two types of antibiotic-free cement (Simplex®, Biomet®) with similar viscosity and also gentamycin-containing cement (Refobacin®). Prepared specimens were used to create cement beads and articulating hip spacers, making a total of six different groups. Two alternative groups were formed by adding the Vancomycin while the cement was in dough phase. Antibiotic release and biological activity were evaluated with immunoassay techniques and agar-disk diffusion methods. All groups showed initial antibiotics surge in the first week, which was 2 to 4 times more evident in the beads group. Antibiotic release and change in release rate were significantly different between Simplex-alternative and Simplex, Biomet, Refobacin-beads, and between Biomet-spacer and Refobacin-beads groups (p<0.05). Elution of antibiotics was not different between mobile spacers prepared with conventional or alternative methods (p>0.05). Biomet cement showed larger diffusion inhibition zone in agar. There was no difference between biological activity of the bead and mobile designs of the Biomet brand (p>0.05). Inhibition zone analyses of agar and disk diffusion tests revealed significant differences between several groups (p<0.05). Cement beads provide superior antibiotic release regardless of cement type or preparation method. Simplex P® cement has lower anti-bacterial efficiency than Biomet®. Different methods for cement and antibiotics mixing and addition of extra vancomycin into the commercially drug loaded cement do not have any effect on the results.

Two-Stage Revision Arthroplasty for the Treatment of Prosthetic Joint Infection.

To review the diagnosis and treatment of prosthetic joint infection (PJI) with a focus on two-stage revision arthroplasty. The text will discuss different spacer constructs in total knee and total hip arthroplasty and will present clinical outcome data for these various options. There is no appreciable difference in infection eradication between mobile and static antibiotic spacers. Mobile spacers have shown improved knee range of motion after second-stage re-implantation. Two-stage revision arthroplasty is the gold standard treatment for PJI. The first stage involves removal of all components, cement, and compromised soft tissues with placement of an antibiotic-impregnated spacer. Spacer options include both mobile and static spacers. Mobile spacers offer maintenance of ambulation and joint range of motion between staged procedures and have shown to be as effective in eradicating infection as static spacers.

Mid-term results of two-stage revision of total knee arthroplasty using a mobile (dynamic) cement spacer in the treatment of periprosthetic infections.

Introduction: Infection of the knee joint after primary total knee arthroplasty is a serious complication. In this work, we would like to evaluate the mid-term results after two-stage revision of total knee replacement in periprosthetic infection using dynamic spacer, in particular with regard to the function of the knee joint after reimplantation.Patients and methods: In this retrospective study, we included patients who were treated in our clinic between 2005 and 2013 due to infection of the knee after total knee arthroplasty. All patients included have had a mobile antibiotic-coated cement spacer implanted after surgical debridement and removal of the components of total knee replacement. Subsequently, reimplantation of total knee replacement was performed when no clinical or paraclinical signs of infection were found. We analyzed all included cases for potential reinfection, examined the range of motion of the knee joint and evaluated the Merle d’Aubigné-Postel score. Statistical evaluation was performed with SPSS 24.0.Results: This study group contains 16 patients (9 women and 7 men) with an average age of 72.0 ± 8.3 years. All patients were followed up for at least 6 months with an average follow-up of 22.5 ± 16.6 months. In all patients a pathogen was isolated intraoperatively during the first-stage surgery (explantation of the knee). Staphylococci were detected in 94% of the cases, streptococci in only one patient. Reimplantation was carried out after 6.2 ± 5.2 months. The average knee flexion in the group of patients without relapse of infection was 103.3° ± 17.1°. Only 3 patients showed extension deficit of max. 20°. The Merle d’Aubigné-Postel Score was 14.4 ± 1.9.Conclusion: Two-stage surgery of total knee replacement with the use of a mobile spacer has its high value in the treatment of periprosthetic infections. The mobile spacers contribute to an advantageous range of motion of the knee joint after reimplantation of a total knee endoprosthesis. However, further studies are required that compare the results after using mobile or static spacer, but with the inclusion of homogeneous patient collective.

Autoclaved metal-on-cement spacer versus static spacer in two-stage revision in periprosthetic knee infection.

Background:Periprosthetic knee infection is troublesome for Orthopedic surgeons and a catastrophy for patients. Reported rates of periprosthetic joint infection following primary total knee arthroplasty (TKA) are 0.39–2%. Two stage revision arthroplasty, which has success rates exceeding 90%, has been the gold standard for treating subacute and chronic periprosthetic infection following TKA. Antibiotic spacers, a well established means of delivering local antibiotic therapy, maintain soft tissue tension during two stage revision arthroplasty. However, controversy remains around whether static or mobile antibiotic impregnated spacers are superior for treating infection following TKA. Various mobile spacers are available, including cement-on-cement, cement-on-polyethylene and metal-on-polyethylene. In this study, the efficacy of the modified metal-on-cement spacer, consisting of reinsertion of the autoclaved femoral component and implantation of antibiotic-loaded cement in the proximal tibia, is assessed.Materials and Methods:Records of 19 patients diagnosed as periprosthetic knee infection were reviewed in this retrospective study. Among these patients, 10 patients received first stage debridement with the autoclaved metal-on-cement spacer and 8 patients with the static spacer, who eventually underwent two-stage re-implantation, were listed in the final comparison. Patient demographics, infection eradication rates, average range of motion (ROM), surgical time and blood loss during the second-stage of the surgery, and Knee Society (KS) knee scores at last followup after revision total knee replacement were clinically evaluated.Results:At a minimum of 2-year followup after re-implantation, infection eradication rates, surgical times, blood loss during the second-stage of the surgery, and KS knee score after re-implantation were similar for the two groups. Patients receiving autoclaved metal-on-cement spacers had superior ROM after re-implantation compared to that of patients with static spacers.Conclusions:The autoclaved metal-on-cement spacer is an effective and simple method for two-stage re-implantation of a periprosthetic knee infection. Through this spacer, the good interim ROM can be achieved without the additional cost of prefabricated molds or new polyethylene tibial inserts. In addition, ROM after re-implantation is better than that with static spacers.

Outcome of total knee replacement following explantation and cemented spacer therapy.

Background: Infection after total knee replacement (TKR) is one of the serious complications which must be pursued with a very effective therapeutic concept. In most cases this means revision arthroplasty, in which one-setting and two-setting procedures are distinguished. Healing of infection is the conditio sine qua non for re-implantation. This retrospective work presents an assessment of the success rate after a two-setting revision arthroplasty of the knee following periprosthetic infection. It further considers drawing conclusions concerning the optimal timing of re-implantation.Patients and methods: A total of 34 patients have been enclosed in this study from September 2005 to December 2013. 35 re-implantations were carried out following explantation of total knee and implantation of cemented spacer. The patient’s group comprised of 53% (18) males and 47% (16) females. The average age at re-implantation time was 72.2 years (ranging from 54 to 85 years). We particularly evaluated the microbial spectrum, the interval between explantation and re-implantation, the number of surgeries that were necessary prior to re-implantation as well as the postoperative course. Results: We reported 31.4% (11) reinfections following re-implantation surgeries. The number of the reinfections declined with increasing time interval between explantation and re-implantation. Patients who developed reinfections were operated on (re-implantation) after an average of 4.47 months. Those patients with uncomplicated course were operated on (re-implantation) after an average of 6.79 months. Nevertheless, we noticed no essential differences in outcome with regard to the number of surgeries carried out prior to re-implantation. Mobile spacers proved better outcome than temporary arthrodesis with intramedullary fixation.Conclusion: No uniform strategy of treatment exists after peri-prosthetic infections. In particular, no optimal timing can be stated concerning re-implantation. Our data point out to the fact that a longer time interval between explantation and re-implantation reduces the rate of reinfection. From our point of view, the optimal timing for re-implantation depends on various specific factors and therefore it should be defined individually.

Two-stage Revision Arthroplasty for Management of Chronic Periprosthetic Hip and Knee Infection

In North America, two-stage revision arthroplasty is the treatment of choice for chronic periprosthetic infection of the hip and knee. Controversy exists regarding the diagnosis of persistent infection, cement spacer design, and duration of antibiotic therapy. Erythrocyte sedimentation rate and C-reactive protein tests have no clear cutoff values for detecting infection before reimplantation of hardware, and aspiration for microbial culture can yield false-negative results. Mobile spacers are as effective as static spacers for eradicating infection, but mobile spacers provide better interim function and may help to make the second stage of surgery technically easier. Some articulating spacer designs have fewer reports of spacer dislocation and fracture than do others. Although prolonged antibiotic therapy has been the standard of care for two-stage procedures, some have suggested that a short course of antibiotics is just as effective. When infection persists despite antibiotic therapy, the second stage of revision arthroplasty should be delayed until the first stage of the procedure is repeated.

Intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty

Cement articulating spacers have been used for the treatment of TKA infection. The disadvantages of commercially available pre-made mobile spacers include limitations in implant size and antibiotic dose, often allowing delivery of only a single antibiotic agent. Hand-made mobile spacers fail to provide a well-shaped and congruently articular surface and have difficulties in maintaining stability. We present a method of intraoperatively-made cement-on-cement antibiotic-loaded articulating spacer for infected total knee arthroplasty. A custom mold was made intraoperatively with bone cement and the standard posterior stabilized TKA provisional components which were of the same size as the original prosthesis. Fabrication of the spacers did not increase the overall surgical time. From 2004 to 2007, 17 infected total knee arthroplasties were treated with two-stage reimplantation. The average length of follow-up was 31 months. One patient required an above-knee amputation for persistent infection. A knee arthrodesis was performed in one case. Ten patients received reimplantation with Nexgen LCCK knee implants. Articulating spacers were retained in situ in five patients. This articulating spacer can help improve knee mobility and function during the interval between stages.

Comparison of static and mobile antibiotic-impregnated cement spacers for the treatment of infected total knee arthroplasty

Infection after total knee arthroplasty (TKA) is a devastating complication, and two-stage reimplantation has evolved as an effective treatment option. This study was undertaken to compare the clinical results and radiological changes associated with static or mobile cement spacer placement for the treatment of infected TKA. Between July 2000 and February 2007, 36 consecutive patients were treated by two-stage reimplantation using antibiotic-impregnated cement spacers (AICS) for infected TKAs. Static spacers were used in 20 knees and mobile spacers in 16 knees. Clinical outcomes included success rates of TKR revisions, ranges of motion (ROM), and Hospital for Special Surgery knee scores (HSS), pain and function scores of the Knee Society (KS), joint exposure methods, and bone loss. In this study, mobile spacers provided better ranges of motion and functional knee scores without concomitant increases in infection rate and bone loss in the initial and mid-term periods.

Static and Mobile Antibiotic-impregnated Cement Spacers for the Management of Prosthetic Joint Infection

Two-stage treatment is currently the most common approach for management of an infected joint prosthesis in the United States. Static antibiotic-impregnated polymethylmethacrylate cement spacers have traditionally been used; increasingly, however, mobile or articulating spacers are being utilized. Advocates of mobile spacers have cited potential advantages, including more effective maintenance of the joint space, allowing for limited weight bearing and facilitating joint motion; possible reduction in bone loss; and local delivery of antibiotics. Because a variety of materials and construction methods is used to make knee and hip spacers, comparisons are difficult. Randomized, prospective studies are needed to determine the best spacers for total knee and total hip arthroplasties.

Outcome of prosthesis exchange for infected knee arthroplasty: the effect of treatment approach

Background and purpose Two-stage revision remains the gold standard in the treatment of infected knee arthroplasty. Lately, good long-term results of direct exchange arthroplasty have been reported. The purpose of this literature review is to compare the clinical outcome achieved with one-stage revision and two-stage revision with different types of spacers.Methods A thorough systematic review of literature was undertaken to idenepsy reports on the treatment alternatives. Papers written in English or including an English abstract, published from 1980 through 2005, and reporting either the success rate in eradication of infection or the clinical status achieved were reviewed. 31 original articles describing the results of 154 one-stage exchange arthoplasties and of 926 two-stage exchange arthoplasties were included. The depth of detail in the description of materials and methods varied markedly, making it impossible to perform a meta-analysis. Instead, a descriptive review of the results is presented.Results With a follow-up of 12–122 months, the overall success rate in eradication of infection was 73–100% after one-stage revisions and 82–100% after two-stage revisions. Reinfection rates were the lowest in series where articulating cement spacers were used, though the follow-up was relatively short. Studies using articulating spacers reported the highest average postoperative ranges of motion. Otherwise, no correlations were observed between the clinical outcome and the length of follow-up, the type of revision, or the type of spacer. The clinical outcome (knee scores and range of motion) of the one-stage revisions was no different from that of the two-stage revisions.Interpretation Two-stage exchange is an effective treatment. Mobile spacers may further improve the range of motion. More experience in one-stage revision is required in order to define its role in the management of infected knee arthroplasties.

Technical Notes and Tips: Poly-Methylmethacrylate Soft-Tissue Spacers to Maintain Tissue Planes During Two-Stage Revision Knee Arthroplasty

Two-stage revision surgery is considered to be the reference standard for deep infections following total knee arthroplasty. Even with the use of preformed mobile poly-methylmethacrylate (PMMA) spacers at first stage revision, the scarring seen at second stage frequently obliterates the suprapatellar pouch and the gutters. Re-forming these planes prior to re-implantation is time-consuming. Following debridement and after fitting the mobile spacers we mould spacers from antibiotic-loaded PMMA cement and place these in the suprapatellar pouch and in the gutters (Fig. 1). At second stage, it is found that these planes are well preserved, facilitating the procedure. Figure 1A Anteroposterior (A) radiograph taken after first stage revision demonstrating the PMMA implants and soft-tissue spacers. Figure 1B Lateral radiograph taken after first stage revision demonstrating the PMMA implants and soft-tissue spacers.

Experimental evaluation of the biomechanical performances of a PMMA-based knee spacer

Infection of knee prostheses is still one of the major concerns of the reliability over time of these implantable devices. The preferred treatment of this condition has turned out to be the use of a knee spacer in a two-stage reimplantation technique. The advantages of this technique associated with the use of a mobile spacer lies both in the possibility for the patient to move during the interim period, thus decreasing the risk of muscle contracture due to immobilisation, as well as in the ability to release antibiotics directly to the site of infection. The evaluation of the biomechanical properties of new mobile spacers preformed in three different sizes has been carried out subjecting the spacers to i) cyclic tests on a knee simulator for 500,000 walking cycles, ii) constraint tests in medio-lateral, antero-posterior and internal–external directions, iii) fatigue tests on the tibial tray. Particular attention was addressed to the evaluation of the mechanical resistance of the devices, to the quantity of wear debris produced during the tests and to the extent that such debris was influenced by the test parameters and geometrical dimensions of the spacers themselves. Results showed no sign of failure for any of the tested spacers, the constraint and fatigue behaviours were similar to those shown by a total knee prosthesis and the amount of debris turned out to be directly correlated to the size of the devices: in conclusion, the devices showed a good level of mechanical performance and, consequently, a sufficiently high degree of suitability for clinical use.

Antibiotic-loaded bone cement spacers in two-stage management of infected total knee arthroplasty.

We reviewed the current use of spacers in the management of the infected knee prosthesis. There are two types of temporary spacers: block or non-articulating spacers and articulating or mobile spacers. Generally, spacers improve mobilisation and hasten recovery with shorter hospital stay between stages. Furthermore, spacers facilitate the second-stage procedure by maintaining joint space, and articulating spacers may also maintain range of motion. Last but not the least, the cost of spacers represents only a small fraction of the total expenses for management of infected knee arthroplasties.

Comparison of a Static with a Mobile Spacer in Total Knee Infection

Patients with infections of a total knee arthroplasty were stratified by medical status. Twenty-six knees in 26 patients treated with a static antibiotic-impregnated polymethylmethacrylate block spacer before 1995 were compared with 22 knees in 22 patients treated after 1995 with a mobile articulating spacer. Both groups were treated with 6 weeks of parenteral antibiotics and had reimplantation within 6 to 12 weeks after placement of the spacer. Followup for the patients who had block spacers was an average 7.5 years (range, 2.8-12.7 years), and followup for the patients with a mobile spacer was an average of 3.8 years (range, 2.6-6.4 years). Results showed that the patients with the mobile spacers had significantly better average range of motion at followup compared with patients who had block spacers (107.8 degrees compared with 93.7 degrees ). The reinfection rate was the same between the two groups at 36 months, 7.6% (two of 26) for the patients with block spacers and 9% (two of 22) for the patients with mobile spacers. Extended followup available for the patients who had block spacers revealed a late reinfection rate of 23% (six of 26) with a new organism. There was no difference in the reinfection rate, with new or old organisms, in healthy hosts compared with patients with as many as two medical problems.

Orientation process in thermotropic comb‐like polymers

AbstractThe influence of magnetic fields on the orientation of comb‐like silicon polymers was investigated by NMR methods. The sensitivity of proton NMR spectroscopy to phase transitions could be proven. Glass transition temperatures could be estimated by means of the super Lorentzian line shape of the wide line NMR signals. Magnetic fields of 2,1 T in connection with special temperature programs are able to effect a macroscopic orientation of the mesogenic side groups which are connected by mobile spacers to the backbone of the flexible polymer. The state of this orientation is preserved in a broad temperature range. The order parameter is derived as a function of temperature.