Spacers

The Inverse Spacer-A Novel, Safe, and Cost-Effective Approach in Routine Procedures for Revision Knee Arthroplasty

Background: A major disadvantage of current spacers for two-stage revision total knee arthroplasty (R-TKA) is the risk of (sub-) luxation during mobilization in the prosthesis-free interval, limiting their clinical success with detrimental consequences for the patient. The present study introduces a novel inverse spacer, which prevents major complications, such as spacer (sub-) luxations and/or fractures of spacer or bone. Methods: The hand-made inverse spacer consisted of convex tibial and concave femoral components of polymethylmethacrylate bone cement and was intra-operatively molded under maximum longitudinal tension in 5° flexion and 5° valgus position. Both components were equipped with a stem for rotational stability. This spacer was implanted during an R-TKA in 110 knees with diagnosed or suspected periprosthetic infection. Postoperative therapy included a straight leg brace and physiotherapist-guided, crutch-supported mobilization with full sole contact. X-rays were taken before and after prosthesis removal and re-implantation. Results: None of the patients experienced (sub-) luxations/fractures of the spacer, periprosthetic fractures, or soft tissue compromise requiring reoperation. All patients were successfully re-implanted after a prosthesis-free interval of 8 weeks, except for three patients requiring an early exchange of the spacer due to persisting infection. In these cases, the prosthetic-free interval was prolonged for one week. Conclusion: The inverse spacer in conjunction with our routine procedure is a safe and cost-effective alternative to other articulating or static spacers, and allows crutch-supported sole contact mobilization without major post-operative complications. Maximum longitudinal intra-operative tension in 5° flexion and 5° valgus position appears crucial for the success of surgery.

Are Cement Spacers and Beads Loaded with the Correct Antibiotic(s) at the Site of Periprosthetic Hip and Knee Joint Infections?

The optimal impregnation of antibiotic-loaded bone cement in the treatment of periprosthetic hip and knee joint infection is unknown. It is also unclear, whether a suboptimal impregnation might be associated with a higher persistence of infection. A total of 93 patients (44 knee, 49 hip) were retrospectively evaluated, and the most common organism was a methicillin-resistant Staphylococcus epidermidis, followed by methicillin-susceptible Staphylococcus aureus. Of all the organisms, 37.1% were resistant against gentamicin and 54.2% against clindamycin. All organisms were susceptible against vancomycin. In 41 cases, gentamicin-loaded beads were inserted and in 52 cases, spacers: (2 loaded only with gentamicin, 18 with gentamicin + vancomycin, 19 with gentamicin + clindamycin, and 13 with gentamicin + vancomycin + clindamycin). The analysis of each antibiotic impregnation showed that complete susceptibility was present in 38.7% of the cases and partial susceptibility in 28%. In the remaining 33.3%, no precise statement can be made because either there was a culture-negative infection or the antibiotic(s) were not tested against the specific organism. At a mean follow-up of 27.9 months, treatment failure was observed in 6.7% of the cases. Independent of which antibiotic impregnation was used, when the organism was susceptible against the locally inserted antibiotics or not tested, reinfection or persistence of infection was observed in the great majority of cases. Future studies about the investigation of the optimal impregnation of antibiotic-loaded bone cement are welcome.

Creation of a Custom-Length, Humeral Antibiotic Cement Spacer for Use in Treatment of Shoulder Periprosthetic Joint Infection

Periprosthetic joint infection of the shoulder is a challenging clinical situation to manage owing to the fastidious organisms often present and delayed clinical presentation. While several treatment options have been described, the mainstay of treatment remains a staged revision with the use of a humeral antibiotic cement spacer. Such spacers are commercially available or can be made by hand. When an extended humeral osteotomy is required to remove a well-fixed long stem humeral component, it may be advantageous to place an antibiotic spacer with a stem length approximately as long as the hardware being removed. This technique demonstrates creation of a custom length, humeral antibiotic cement spacer for use in treatment of shoulder periprosthetic joint infection.

Hip Spacers in Two-Stage Revision for Periprosthetic Joint Infection: A Review of Literature

Infection after total hip arthroplasty (THA) is a devastating complication with significant consequences for patients. In literature, single and two-stage revision, irrigation and debridement, Girdlestone resection arthroplasty, and arthrodesis and amputation are reported as possible treatments. Recently, two-stage revision has become popular as the gold standard treatment for chronic hip joint infections after THA. In this review, we evaluate the current literature about microbiology of periprosthetic joint infections and the use of antibiotic-loaded cement spacers. We aim to give an overview about indications, clinical results, and mechanical complications for spacers implantation, evaluating also selection criteria, pharmacokinetic properties, and systemic safety of the most frequently used antibiotics.

Daptomycin-Tobramycin Cement Beads have Lethal Local Antibacterial Effect in Resistant Periprosthetic Joint Infections

Background Resistant periprosthetic joint infection (PJI) can be a devastating complication of surgery and is difficult to treat. We attempted to identify the utility of Daptomycin/Tobramycin-impregnated polymethylmethacrylate (PMMA) beads in resistant PJIs. Methods Charts of patients with hip or knee PJI at a single academic medical center, with surgeries performed from May 2008 through May 2018, were reviewed retrospectively. The diagnosis of PJI was consistent with the Musculoskeletal Infection Society recommendations. Prosthetic joints underwent radical anterior-posterior synovectomy and placement of antibiotic cement beads in the infected joint. Clinical cure rate and local intraarticular antibiotic concentration were measured. Results Forty-four patients experienced 53 episodes of PJI, requiring 88 surgeries. There was a fairly even split between hip and knee PJI. The cure rate was 92% (11/12) for patients who had any infection with methicillin-resistant staphylococci during the evaluation period, compared with 62% (13/21) for patients with methicillin-susceptible Staphylococci. On days one and seven, the addition of tobramycin increased daptomycin concentrations by 47% and 3374%, respectively, for beads made onsite compared to elution of daptomycin alone. Elution increased by 44% and 8394%, respectively, for commercial beads compared to beads fabricated onsite. Conclusions Daptomycin-Tobramycin-loaded PMMA beads are safe and powerful bactericidal agents in prosthetic joint infections.

Double-layered antibiotic-loaded cement spacer as a novel alternative for managing periprosthetic joint infection: an in vitro study

BACKGROUND

Previous studies comparing antibiotic-loaded calcium phosphate cement to polymethylmethacrylate cement reported that although the former has higher elution volumes over a longer period, it is mechanically weak when used alone. To counter this problem, a double-layered antibiotic-loaded cement spacer in which calcium phosphate cement is coated with polymethylmethacrylate cement was created.

METHODS

In this study, we compared the double-layered spacer to the polymethylmethacrylate cement spacer in terms of eluent antibiotic concentration, bioactivity against methicillin-resistant Staphylococcus aureus, and mechanical strength. Double-layered and polymethylmethacrylate cement spacers that were loaded with vancomycin (VCM) were prepared and immersed in phosphate buffer for 84 days. To facilitate VCM elution from calcium phosphate cores in double-layered spacers, we also drilled multiple holes into the calcium phosphate layer from the spacer surface.

RESULTS

We found that VCM concentrations in double-layered spacer eluents were higher than those in polymethylmethacrylate cement spacer eluents. The double-layered spacer also had higher bioactivity than the polymethylmethacrylate cement spacer. Although the polymethylmethacrylate cement spacer eluent lost the ability to inhibit bacterial growth on day 56, the double-layered spacer eluent maintained this ability for the duration of our study. Finally, the double-layered spacer retained high mechanical strength throughout the study period.

CONCLUSIONS

The beneficial biomechanical and drug-eluting properties of the double-layered spacer might qualify it to serve as a promising biomaterial that could be used for managing periprosthetic joint infections.

Preliminary results of a novel spacer technique in the management of septic revision hip arthroplasty

INTRODUCTION

Mechanical failure due to dislocation, fracture and acetabular wear is a major complication associated with the use of spacers in the management of periprosthetic joint infection (PJI). We have developed a novel custom-made spacer in the setting of two-stage septic revision hip arthroplasty and present the preliminary results of our technique.

MATERIALS AND METHODS

Between May 2015 and November 2017, 30 patients underwent hip revision using the ENDO spacer technique in the setting of a two-stage septic exchange arthroplasty. The technique involves the dual mobility liner and the downsized stainless cemented straight stem in combination with antibiotic-loaded PMMA bone cement. The primary outcome measure was the overall spacer complication rate, particularly spacer dislocation. Furthermore, functional outcome using the Harris Hip Score (HHS) before spacer implantation and prior re-implantation was evaluated.

RESULTS

The mean age of the patients was 69.8 years (range from 45 to 85; SD = 9.9 years). No microorganisms were preoperatively found in 23 (76.7%) cases. Successful re-implantation was performed in all patients after a mean spacer duration time of 53.6 days (range 14-288 days; SD = 48.2). Spacer-related complications occurred in only two patients (6.7%). The HHS significantly improved from 34.0 (range 3-62; SD = 15.1) to 48.1 (range 11-73; SD = 15.7) (p = 0.0008).

CONCLUSIONS

The ENDO spacer surgical technique is a feasible option in the treatment of periprosthetic joint infection (PJI), with a low dislocation rate. Furthermore, it allows early mobilization with the possibility of full-weight bearing.

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.

[Dynamic versus static cement spacer in periprosthetic knee infection: A meta-analysis]

BACKGROUND

The standard of care for treatment of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is two-stage revision arthroplasty. The cement spacer in the interim period can be classified as either a static/non-articulating spacers (e.g., traditionally simple cement blocks) or a mobile/articulating spacer.

OBJECTIVES

The goal of the present meta-analysis is to analyze the outcomes with regard to infection control between dynamic and static knee spacers in the treatment of infected TKA with a minimum 3-year follow-up.

MATERIALS AND METHODS

We systematically reviewed the literature for potentially relevant articles addressing two-stage revision of an infected TKA using the MEDLINE computerized literature databases. Only 25 articles studies with a minimum follow-up examination of 36 months met the inclusion criteria and were analyzed with regard to infection control after reimplantation between static (318 cases) and dynamic group (700 cases).

RESULTS

At latest follow-up, the eradication rate in the dynamic group was 89.7% (range 63-100%; SD 9.1) and in the static group 84.8% (range 67-92.4%; SD 7.8; p = 0.32). We are unable to comment on the Hospital for Special Surgery (HSS) Score and complication rates between static and dynamic spacers because the majority of the studies did not report on this.

CONCLUSION

The data show that there are no differences regarding infection control between static and dynamic spacers in the treatment of infected TKA.

Treatment of Periprosthetic Knee Infection With a Two-stage Protocol Using Static Spacers

BACKGROUND

Two-stage exchange arthroplasty is a standard approach for treating total knee arthroplasty periprosthetic joint infection in the United States, but whether this should be performed with a static antibiotic spacer or an articulating one that allows range of motion before reimplantation remains controversial. It is unclear if the advantages of articulating spacers (easier surgical exposure during reimplantation and improved postoperative flexion) outweigh the disadvantages of increased cost and complexity in the setting of similar rates of infection eradication.

QUESTIONS/PURPOSES

The purposes of this study were (1) to determine the ultimate range of motion; and (2) to determine the proportion of patients who remained free of infection at a minimum 2 years after treatment with static antibiotic spacers as part of a two-stage revision TKA for the treatment of periprosthetic joint infection.

METHODS

Between 1999 and 2011, we treated 121 patients with chronically infected TKAs, of whom three had medical comorbidities precluding a two-stage exchange, four had died before 2-year followup for reasons other than the surgical intervention, and seven were lost to followup. The remaining 107 patients (109 knees; 53 men and 54 women) were treated using a two-stage approach with static spacers and are evaluated here at a mean of 3.7 years (range, 2.0-9.8 years); no patients were treated with articulating spacers during this study period. Twenty-five percent (27 of 109) of the organisms isolated the first-stage procedure were resistant to methicillin and/or vancomycin. Median age at the time of reimplantation was 67 years (range, 42-89 years). Range of motion was measured by an independent physical therapist with a standard goniometer. Knee Society knee and function scores were calculated before the first stage and at the 2-year mark. Because many of these patients were treated before consensus definitions of infection were established, we made the diagnosis of infection (and established that a patient was believed to be free of infection) using the approaches prevalent at that time, which generally included presence of a sinus tract communicating directly with the implant, two positive tissue cultures, or a combination of cultures, fluid analysis, and serology.

RESULTS

Postoperatively, 67 knees had full extension and no patients had a flexion contracture > 10°. Median flexion was 100° (range, 60°-139°). Thirty-nine knees had postoperative flexion > 120°. Ninety-four percent of patients were clinically free of infection at last followup.

CONCLUSIONS

Our two-stage exchange protocol with static spacers yielded comparable flexion and infection eradication when compared with other recent studies that have used articulating spacers. The large proportion of resistant organisms is alarming. Future multicenter studies should compare static with articulating spacers and should evaluate both cost and efficacy, because our study suggests that adequate range of motion can be achieved without the added cost of the articulating spacer.

LEVEL OF EVIDENCE

Level IV, therapeutic study.