Articulating antibiotic impregnated spacers in two-stage revision of infected total knee arthroplasty

How I do it: 1st stage revision TKA

This article covers the key steps and decisions that we make when performing a 1st-stage revision Total Knee Arthroplasty (TKA) at the Avon Orthopaedic Centre and includes more detailed technique and tips regarding how we make our spacers. The first stage of a two-stage protocol should be done in a stable patient with information about the organism, and with the option of plastic surgery flap coverage if required. It should ideally be performed in the unit that is going to perform the second stage, and the operation note should document the soft-tissues, bone loss and extensor mechanism issues that will influence planning for the second stage. Nothing will make up for a bad debridement, so we focus on this as the key step for infection clearance. Infection clearance is equivalent between mobile and static spacers, but patients generally prefer having the better mobility and function of a mobile spacer. We recommend a mobile spacer, unless there is compromise to ligaments or extensor mechanism, or if bone loss is large. Whichever spacer you use, it should aim to: deliver appropriate antibiotics; allow stability, pain relief and some function and weight-bearing prior to the second stage. Doing a good technical job with the spacer is important because you do not want complications with the spacer to cause harm or necessitate a return to theatre or re-operation sooner than planned. Ideally the second stage should be performed when the surgeon & MDT team deem it appropriate clinically and when the patient is fit and ready for further surgery.

Selected Heat-Sensitive Antibiotics Are Not Inactivated During Polymethylmethacrylate Curing and Can Be Used in Cement Spacers for Periprosthetic Joint Infection

BACKGROUND

Antibiotic use in polymethylmethacrylate (PMMA) spacers has historically been limited to those which are "heat-stable" and thus retain their antimicrobial properties after exposure to the high temperatures which occur during PMMA curing.

METHODS

This study examines the requirement of "heat stability" by measuring temperatures of Palacos and Simplex PMMA as they cure inside commercial silicone molds of the distal femur and proximal tibia. Temperature probes attached to thermocouples were placed at various depths inside the molds and temperatures were recorded for 20 minutes after PMMA introduced and a temperature curve for each PMMA product was determined. A "heat-stable" antibiotic, vancomycin, and a "heat-sensitive" antibiotic, ceftazidime, were placed in a programmable thermocycler and exposed to the same profile of PMMA curing temperatures. Antimicrobial activity against Staphylococcus aureus was compared for heat-treated antibiotics vs room temperature controls.

RESULTS

Peak PMMA temperatures were significantly higher in tibial (115.2°C) vs femoral (85.1°C; P < .001) spacers. In the hottest spacers, temperatures exceeded 100°C for 3 minutes. Simplex PMMA produced significantly higher temperatures (P < .05) compared with Palacos. Vancomycin bioactivity did not change against S aureus with heat exposure. Ceftazidime bioactivity did not change when exposed to femoral temperature profiles and was reduced only 2-fold with tibial profiles.

CONCLUSION

The curing temperatures of PMMA in knee spacers are not high enough or maintained long enough to significantly affect the antimicrobial efficacy of ceftazidime, a known "heat-sensitive" antibiotic. Future studies should investigate if more "heat-sensitive" antibiotics could be used clinically in PMMA spacers.

Two-stage revisions for culture-negative infected total knee arthroplasties: A five-year outcome in comparison with one-stage and two-stage revisions for culture-positive cases

BACKGROUND

Culture-negative periprosthetic joint infection (PJI) is very intractable when dealing with an infected total knee arthroplasty (TKA) patient. Two-stage revision has been proved to be a reliable solution for PJI patients. Whether it is still credible for culture-negative infected patients remains uncertain.

METHODS

Our group retrospectively reviewed all total knee revision patients from January 2003 to January 2014, 145 PJI patients were diagnosed as infection with the PJI diagnostic criteria and 129 patients were successfully followed. As different treating strategies were utilized, these patients were divided into culture-negative (18 cases, CN) group, culture-positive with one-stage revision group (CP1, 21 cases) and culture-positive with two-stage revision group (CP2, 87 cases) groups. The CN group and CP2 group underwent two-stage revision with antibiotic loaded cement spacers and intravenous antibiotics, CP1 group received one-stage revision. All the culture results and relevant medical records were thoroughly reviewed.

RESULTS

The mean follow-up time was 59.5 ± 32.3 months (range 12-158 months). The culture-negative rate was 14.2%. The overall infection control rate was 92.12%. Infection recurrence was observed in two cases in CP1 group (9.09%), six cases in CP2 group (6.90%) and two cases in CN group (11.1%). The reinfection rate of culture-negative patients and culture-positive patients was 7.34% and 11.1% with no significant difference (p = 0.94). No statistically difference was observed between CP2 group and CN group (p = 0.90). No Spacer fracture or dislocation was observed.

CONCLUSION

With combined or broad spectrum antibiotics, two-stage revision showed comparable outcome when treating culture-negative infected TKA patients at five-year follow-up.

Complications associated with 133 static, antibiotic-laden spacers after TKA

PURPOSE

Periprosthetic infection after total knee arthroplasty (TKA) is a devastating complication, with a two-stage revision currently the 'gold standard' treatment for chronic infections. There is, however, a lack of information about mechanical complications during this treatment. The purpose of this study was to determine: (1) the rate and type of mechanical complications encountered during a two-stage exchange revision for periprosthetic infection of the knee and (2) possible factors of influence.

METHODS

Between 2000 and 2011, 133 patients received an antibiotic-laden cement spacer as part of a two-stage protocol. The overall frequency and types of complication were recorded (fissure/fracture of the tibia or femur, spacer fracture, subluxation of the patella, peroneus affection, wound healing disorder and mobilization under anaesthesia based on a constricted ROM). Also analysed were potential influencing factors (BMI, ASA classification, length of the interval with the enclosed spacer, revision needed after explantation, revision needed after reimplantation, complications after primary TKA, service life of the primary prosthesis) in terms of the overall outcome (possibility of reimplantation, complications during the two-stage protocol).

RESULTS

The mean age at the time of the first stage operation was 70.1 ± 9.9 years. Overall, 20 of 133 patients suffered one of the complications mentioned above (15 %). Fracture/fissure of the tibia occurred in nine cases (6.8 %) and fracture/fissure of the femur in three (2.3 %). There were also three mobilizations under anaesthesia after TKA reimplantation, two affections of the peroneus nerve, one spacer fracture, one subluxation of the patella and one wound healing disorder. The influencing factors on the overall outcome were revision after reimplantation (reinfection, p = 0.002), revision after explantation (reinfection, p = 0.044), prior aseptic revision after primary TKA (reimplantation, p = 0.019), and prior two-stage revision (reimplantation, p = 0.002).

CONCLUSION

A two-stage revision arthroplasty using a static cement spacer is an effective therapy for infected TKAs. The complication rate of 15 % (including restricted ROM after reimplantation) is acceptable. Influencing factors (revision needed after reimplantation, revision needed after explantation) can be demonstrated and should be avoided during the two-stage protocol.

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.

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

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

The influence of storage temperature on the antibiotic release of vancomycin-loaded polymethylmethacrylate

Periprosthetic joint infection is devastating and increases medical expenditure and socioeconomic burden. Antibiotic-loaded cement spacer is useful in the interim period before the reimplantation surgery. Prefabricated antibiotic-loaded cement spacers can decrease operation time but have been limitedly used clinically. In the literature, there is no clear recommendation on the storage temperature for the prefabricated cement spacers. We used an in vitro model to analyze whether the storage temperature at 25°C, 4°C, or −20°C for 2 weeks or 3 months could affect the release of vancomycin from the cement. We found that the storage temperature and time had no significant effects on the pattern and amount of vancomycin release. The patterns of vancomycin release from the cement stored at different temperatures were similar with an abrupt release in the first 3 days and steadily declined in the following period. This study provides a preliminary result to justify the storage of fabricating antibiotic-loaded cement spacer sterilely packed at room temperature. Further studies to examine the effects of storage temperature on the mechanical strength and the release pattern of other antibiotics should be done to provide more evidence to support the clinical use of prefabricated ready-to-use antibiotic-loaded cement spacer.