Aim. The aim of this study is to evaluate if the gentamycin elution from bone cement is influenced by the timing of application of the antibiotic powder. Method. This was an experimental in vitro study that compared the elution properties of different formulation of gentamycin from a commercially available hip, knee and shoulder cement spacers. Four different experimental models were prepared. Five different spacers were prepared for each experimental mode and for each joint. We compared four different formulation of cement spacers: spacer #1, in which the spacer was prepared with a premixed bone-cement antibiotic mixture; spacer #2, in which the spacer was prepared by adding antibiotic powder to the bone cement at the time of spacer preparation; spacer #3, in which the spacer was prepared as spacer #2 but was stored for two months before starting the experiment; spacer #4, in addition to the gentamycin, other two antibiotics (tobramycin and vancomycin) were added to the bone cement. Gentamycin concentration was documented at seven intervals of time: T0 = 0h, T1 = 1h, T2 = 24h, T3 = 1W, T4 = 2W, T5 = 1M, T6 = 3M and T7 = 6M. The gentamycin elution at each interval of time was evaluated by using a T-student test. Results. Spacer #2, in which the gentamycin powder was added to the bone cement at the time of spacer preparation showed the higher gentamycin elution at each interval of time observed. In addition, Spacer #1, in which gentamycin powder was premixed with the bone cement showed a higher gentamycin elution when compared with spacer #3, in which the spacers were stored for two months to simulate the preformed spacers. Lastly, the addition of different antibiotic to the bone cement increases the gentamycin elution from the spacers (as demonstrated by spacer #4 model). Conclusions. a higher gentamycin elution was observed if spacer was prepared at the time of surgery when compared with preformed spacer. Lastly, our study confirmed the synergistic effect of adding one or more antibiotics with the aims to increase gentamycin elution

Aim. Due to medical and organizational factors, it occurs in everyday practice that spacers are left in place longer than originally planned during a two-stage prosthesis exchange in the case of prosthetic joint infections. Patients are severely restricted in their mobility and, after initial antibiotic administration, the spacer itself only acts as a foreign body. The aim of this study is to analyze whether the duration of the spacer in situ has an influence on the long-term success of treatment and mortality. Method. We retrospectively studied all 204 two-stage prosthesis replacements of the hip and knee from 2012 to 2016 with a minimum follow-up of two years at an arthroplasty center with 3 main surgeons. The duration of the spacer interval was divided into two groups. Patients replanted within ten weeks (as is standard in multiple algorithms) after systemic antibiotic treatment were assigned to the ‘Regular Spacer Interval (< 70 days)’ group. If the spacer interval was longer, they were assigned to the ‘Long Spacer Interval (≥ 70 days)’ group. Results. Patients were on average 67.69 years old (SD 12.3). The mean duration of the spacer-interval was 100.9 days (range: 423.0; SD, 60.0). In 62 patients reimplantation could be performed within 70 days after explantation, in 142 patients this took longer (max. 438 days). In 26 patients, the spacer had to be changed at least once during this period (11 patients in the hip group, and 15 patients in the knee group). In the remaining cases, other medical or organizational reasons delayed replantation. Both groups were comparable concerning Charlson Comorbity Index, age, number of previous surgeries and laboratory infection markers. There was no statistically significant influence of the duration of the spacer interval on the infection free survival (n=204, p=0.32). There was also no influence on mortality (n=204, p=0.35) and aseptic implant failure (n=204, p=0.15). Conclusions. The timely replantation of a knee or hip prosthesis seems to be reasonable in general because the patients are strongly limited in their mobility and daily activities by the spacer. However, there does not seem to be a negative influence on infection eradication and survival due to a long spacer interval

Aim

Studies have shown that retention of antibiotic cement spacer in selected elderly patients with low functional demand represents a viable option for periprosthetic joint infections (PJI) treatment^1,2.

The aim of this study is to compare the efficacy in infection treating among modular taylored preformed and hand-made antibiotic spacers. Our hypothesis is that modular tailored preformed spacer provides a better rate of infection resolution, better radiological and functional outcomes compared to hand-made spacers.

Successful treatment of the infected arthroplasty remains a major concern to the revision surgeon. We aim to present our audit of the use of the Biomet Femoral Spacer in staged revision of the infected total hip arthroplasty. Following removal and thorough debridement of the infected joint the spacer is created using the Biomet mould and the surgeon’s choice of cement with additional antibiotics. Custom moulding allows for the incorporation of intramedullary devices to stabilize periprosthetic fractures. The patient is then able to mobilize non weight bearing on the spacer until infectious parameters return to normal, before the second stage is attempted. In our series fifty cases have been identified. Two dislocations, two prosthesis fractures and three repeat second stages are noted. Examples will be presented. We believe the Biomet Femoral Spacer has a definite role in the management of this difficult problem

Introduction. Temporary use of antibiotic-impregnated polymethylmethacrylate (PMMA) bone cement spacers in two-stage revisions is considered to be standard of care for patients with a chronic infection of a joint replacement. Spacers should be wear resistant and load-bearing to avoid prolonged immobilisation of the patient and to reduce morbidity. Most cement spacers contain barium sulphate or zirconium dioxide as radio-opaque substrate. Both are quite hard materials that may negatively influence the wear behaviour of the spacer. Calcium carbonate is another radio-opaque substrate with lower hardness potentially increasing the wear resistance of the spacer materials. The purpose of the study was to compare a prototype PMMA knee spacer (calcium carbonate loaded) with a commercially available spacer (containing barium sulphate) regarding the wear performance and particle release in a knee wear simulator. Material and Methods. Spacer K (TECRES, Italy) was used as barium sulphate (10%) containing spacer material. A prototype material (Heraeaus Medical, Germany) with 15% calcium carbonate was compared. Both were gentamicin impregnated, ready-made for clinical application (preformed) and consist of a tibial and a femoral component. Force-controlled simulation was carried out on an AMTI knee simulator. The test parameters were in accordance to ISO 14243–1 with a 50% reduced axial force (partial weight bearing). Tests were carried out at 37 °C in closed chambers filled with calf serum. Tests were run for 500,000 cycles at a frequency of 1 Hz. For wear analysis, gravimetric wear measurements according to ISO 14243–2 and wear particle analysis according to ASTM F1877–05 were performed. Results. Fig. 1 presents the results of the gravimetric wear measurements. For the Spacer K cement a mean articular wear mass of 375.53±161.22 mg was determined after 500.000 cycles (femoral components: 149.55±17.30 mg, tibial components: 225.98±153.01 mg). The prototype cement showed lower mean total wear of 136.32±37.58 mg (femoral components: 74.32±33.83 mg, tibial components: 61.99±15.74 mg). However, a statistically significant lower wear rate was only seen for the femoral components (p=0,027). In Fig. 2 isolated PMMA wear particles are shown and the morphological characteristics are given in Tab. 1. Discussion and conclusion. The prototype material showed better wear performance in terms of gravimetric wear and particle release. Thus calcium carbonate seems to be a promising material as radio-opaque substrate in PMMA spacers. Nevertheless, the wear amount released from both spacer materials is much higher as compared to conventional total knee replacements with polyethylene inserts. In this context biological reactions against PMMA particles and an increased release of cytokines have been reported in vitro [1] and furthermore, the promotion of osteolysis has been shown in vivo in the presence of PMMA particles [2]. As a clinical consequence we suggest excessive debridement during removal of the cement spacer components to reduce the risk of third body wear for the final joint replacement. Beside the wear performance further studies are essential to prove the mechanical stability and the antibiotic release kinetics for the prototype cement

The Dynesys is a flexible posterior stabilization system that is designed to preserve intersegmental kinematics and reduce loading at the facet joints. The purpose of this study was to determine if the length of the Dynesys spacer has an effect on range of motion (ROM) at the implanted level. Spacer length was found to significantly affect ROM in all three loading directions with and without a follower preload. The longer spacer increased ROM and the shorter spacer decreased ROM, largely due to differences in segmental compression between the two. The Dynesys, a flexible posterior stabilization system that provides an alternative to fusion, is designed to preserve intersegmental kinematics and alleviate loading at the facet joints. Recent biomechanical evidence suggests that motion with Dynesys is less than the intact spine (Schmoelz, 2003). The purpose of this investigation was to determine if the length of the Dynesys spacer contributes to differences in range of motion (ROM) at the implanted level. Ten cadaveric lumbar spine segments (L2-L5) were tested by applying a pure moment of ±7.5Nm in three directions of loading with and without a follower preload of 600N. Test conditions included: intact, injury at L3-L4, Dynesys at L3-L4 (standard spacer), long spacer (+2mm), and short spacer (−2mm). Intervertebral rotations were measured using an optoelectronic camera. Pressure sensors placed inside the joint capsules measured facet loads. Statistical significance was determined using repeated measures ANOVA. Spacer length had a significant effect on ROM in all three loading directions with and without a follower preload. Initial contact loads within the facet joints were 150% and 64% that of the standard spacer for the short and long spacer, respectively. The magnitude of distraction of the segment affects ROM. Shorter spacers increased segmental compression of the intervertebral disc and facet joints and therefore reduced ROM. With a follower preload, the segment is further compressed and ROM is further reduced. The results contribute to an understanding of the design of such implants and could help guide future research. Funding: Synos Foundation, Switzerland, National Science and Engineering Research Council of Canada (NSERC). Please contact author for table or diagram

Background: A knee functional spacer made of antibiotic-loaded acrylic cement was used for treatment of infected TKA with two-stage exchange arthroplasty procedure. Materials and Methods: Spacer K is a preformed articulated spacer with the characteristics of an ultra-congruent condylar knee-prosthesis, made of acrylic cement impregnated with antibiotic (gentamicin). The device, industrially preformed in 3 sizes (commercial name Spacer K, Tecres), with standardised mechanical and pharmacological performances, was implanted in 20 consecutive patients affected by early (12) and late (8) infection according Segawa classification. Infection was caused by CoNs (14 cases), MSSA (2), Micrococcus spp (1), Enterococcus spp. (1). In 2 cases the germ was not detected. All knees presented the integrity of extensor apparatus and of peripheral ligaments (medial), furthermore type I & II bone loss according to Engh’s classification. Mean implantation time was 12 wks. Post-op following std. rehabilitation program as with primary TKR. We evaluated: healing of infection (clinical parameters, CPR, ESR, biopsy); clinical results and functional outcome (KSS); mechanical device behaviour (breakage, wear: macro – and microscopic surface evaluation, histological examination of peri-prosthetic tissues); possible related complications (bone loss, instability or dislocation, loosening: intra- and postoperative evaluation, x-ray study). . Results: Minimum F.U. was 6 months, maximum 51. Healing of infection process was observed in all patients. The KSS score, after definitive reimplantation, has been excellent or good in more than 70% of patients as well as the functional score. Pain was absent but in 1 patient (mild); ROM remained unchanged between first and second stage or improved after definitive reimplantation; patients judged the result excellent or good in 85%. The walk ability was good in 60%, excellent in 15%. Seventy seven per cent of patients went on only cructh, but of these at least, one third could walk without anything. the patient’s judgement has been excellent. Neither breakage, or macroscopic wear signs were detected. No complications related to the use of the device were observed. (one case of dislocation due to pre-existing insufficiency of the extensor apparatus). Conclusions: In a reasoned costs benefits ratio, the use of an articulated knee spacer in two-stage septic revisions should be considered the preferred option

A knee functional spacer made of antibiotic-loaded acrylic cement was used for treatment of infected TKA with two-stage exchange arthroplasty procedure. The Spacer K is a preformed articulated spacer with the characteristics of an ultra-congruent condylar knee-prosthesis, made of acrylic cement impregnated with antibiotic (gentamicin). The device, industrially pre-formed in 3 sizes (Spacer K, Tecres), with standardised mechanical and pharmacological performances, was implanted in 21 consecutive patients all affected by late (8) infection according Segawa classification. Infection was caused by CoNs (16 cases), MSSA (1), Micrococcus spp (1), Enterococcus spp. (1). In 2 cases the germ was not detected. All knees presented the integrity of extensor apparatus and of peripheral ligaments (medial), furthermore type I & II bone loss according to Engh’s classification. Mean implantation time was 12 wks. Post-op following std. rehabilitation program as with primary TKR. We evaluated: healing of infection (clinical parameters, CPR, ESR, biopsy); clinical results and functional outcome (KSS); mechanical device behaviour (breakage, wear: macro – and microscopic surface evaluation, histological examination of peri-prosthetic tissues); possible related complications (bone loss, instability or dislocation, loosening: intra- and postoperative evaluation, x-ray study). The results obtained shows that the spacer K is effective and safe

The use of antibiotic-spacer, it is essential to treat infections in orthopedics. They play a dual role, to fight the infection directly on the outbreak and keep the length or the articulation of the limbs thus facilitating the second operation. To date it is not known, the superiority of use of 3 antibiotics compared to two. Authors try to compare industrial preformed spacers with two antibiotics with custom made spacers with three antibiotics to assess (a) the control of infection, (b) complications, (c) quality of life, (d) pain and (e) patient satisfaction.

137 patients treated at the Institute Codivilla-Putti from January 2010 to December 2012 were considered: 68 patients treated with antibiotic preformed spacer (clindamycin + gentamicin) or (Erythromycin + Colistin), 69 patients treated with antibiotic spacer added with 3 antibiotics (clindamycin + gentamicin + vancomycin) or (Erythromycin Vancomycin + Colistin).

Demographic data were collected:

type and site of infection (classified by Cerny-Mader)

Primary outcome of infection control or relapse after at least 12 months of follow-up were assessed. Complications were recorded. Each patient completed a test on the quality of life and a satisfaction scale self-referenced.

After a mean follow-up of 33.82 months (SD 14:50), at the end of the treatment, at last follow up 15/133 were infected. 4 died from other causes not correlated with infection, whit a 11.3% rate of reinfection.

Up to our knowledge, there is only one study using the procedure in two steps comparing the use of spacers loaded with 2 or 3 antibiotics. Our results show that a revision protocol in two steps with 3 antibiotic loaded spacers have a high success rate in the treatment of chronic osteomyelitis. We can observe that patients treated with custom-made cements are 4 percentage points lower than those treated with preformed cements, but there are no statistically significant differences in the rate of recurrence of infection. Our results suggest that a two stages procedure with three antibiotic loaded spacers should be considered in selected patients to avoid rescue procedures, such as amputation and arthrodesis. We think is important to do more randomized trials, controlled, prospective study with a larger group to detect statistically significant differences.

Objectives

Preclinical data showed poly(methyl methacrylate) (PMMA) loaded with microsilver to be effective against a variety of bacteria. The purpose of this study was to assess patient safety of PMMA spacers with microsilver in prosthetic hip infections in a prospective cohort study.

Introduction: Infection is a challenging problem in orthopaedic surgery. In oncologic and revision surgery large prosthesis are placed during long procedures, even in patients with immunocompromised status. Infection rates here are reported up to 10%. Infections may necessitate large segmental resections thereby creating large defects. This defect can be filled with antibiotics loaded beads that release the substances locally to sterilise the defect. In recent years solid antibiotic loaded bone cement spacers have been applied. These spacers fill the defect, stabilize the extremity, release antibiotics and keep the soft tissues on their original length. Additionally, the patients will be able to preserve mobile function as well. In small defects prefabricated bone cement spacers temporarily replace the infected hip or knee prosthesis. For larger segmental of terminal defects there are no readily available constructs.

Purpose: To report short term outcome of a newly developed customized spacer concept for treatment of large segmental resections after prosthetic infection or osteomyelitis.

Material and Methods: We have treated 13 patients with large segmental defects after infection treatment with customized antibiotic bone cement spacers reinforced with strong intra-medullar implants like the Gammanail, the DFN and the UHN.

Results: These customized spacers are easy to make, fill the defect, stabilize the extremity, release antibiotics, keep the length of the soft tissues and allow patients to practice and preserve joint function as well. In 11 of 13 patients operated with an interim construct like this, a successful reimplantation of a tumor prosthesis was performed.

Conclusion: With customized antibiotic bone cement spacers augmented with a solid implant one can fill the defect, stabilize the extremity, release antibiotics and keep the soft tissues on their original length and keep function as well in infected tumorprosthesis. Successful reimplantation could be performed in 11 of 13 cases.

Aim

To improve the challenging treatment of periprosthetic joint infections (PJI), researchers are constantly developing new handling methods and strategies. In patients with PJI after total knee arthroplasty (TKA) and severe local or systemic comorbidities, a two-stage exchange using a temporary antibiotic loaded PMMA-spacer is considered gold standard. This method has undisputed advantages, however, the increased risk of biofilm formation on the spacer surface, bone defects and soft tissue contractions after a six-week spacer interval are severe limitations. Our hypothesis is that a vacuum sealed foam in combination with constant instillation of an antiseptic fluid can address these drawbacks due to a significantly reduced spacer interval.

Aim

The primary endpoint of this study is to characterize the progression of bone defects at the femoral and tibial side in patients who sustained PJI of the knee that underwent two-stage revision with spacer implantation. In addition, we want to analyze the differences between functional moulded and hand-made spacers.

Aim

The preparation of antibiotic-containing polymethyl methacrylate (PMMA), as spacers generates a high polymerization heat, which may affect their antibiotic activity; it is desirable to use bone cement with a low polymerization heat. Calcium phosphate cement (CPC) does not generate heat on polymerization, and comparative elution testings are reported that vancomycin (VCM)-containing CPC (VCM-CPC) exceeded the antibiotic elution volume and period of PMMA (VCM-PMMA). Although CPC alone is a weak of mechanical property spacer, the double-layered, PMMA-covered CPC spacer has been created and clinically used in our hospital. In this study, we prepared the double-layered spacers: CPC covered with PMMA and we evaluated its elution concentration, antimicrobial activity and antibacterial capability.

Aims

We propose a state-of-the-art temporary spacer, consisting of a cobalt-chrome (CoCr) femoral component and a gentamicin-eluting ultra-high molecular weight polyethylene (UHMWPE) tibial insert, which can provide therapeutic delivery of gentamicin, while retaining excellent mechanical properties. The proposed implant is designed to replace conventional spacers made from bone cement.

Infection remains as one of the major challenges of total joint surgery. One-stage irrigation, debridement and reimplantation or two-stage revision surgery with a temporary implantation of antibiotic eluting bone cement spacer followed by reimplantation are two methods often used to treat infected patients with mixed outcomes. Like bone cement, ultra-high molecular weight polyethylene (UHMWPE) can also be used as a carrier for antibiotics. Recently, we demonstrated that vancomycin and rifampin can be successfully delivered from UHMWPE implants at therapeutic levels to eradicate Staphylococcus aureus biofilm in a lupine animal model. There are regulatory challenges in translating these types of combination devices in to clinical use. One approach is to follow a stepwise strategy, with the first step of seeking clearance for a temporary UHMWPE spacer containing gentamicin sulfate. In this study, we explored the effect of gentamicin sulfate (GS) content in UHMWPE on GS elution rate and antimicrobial activity against methicillin-sensitive S. aureus(MSSA). We also assessed the effect of spacer fabrication on the activity of gentamicin sulfate.

We prepared and consolidated UHMWPE/GS blends in varying concentrations. After consolidation, we fabricated test samples with surface area (350mm2) to volume (300mm3) ratio of 1.2 for elution in 1.5ml phosphate buffered saline at body temperature for up to six months and quantified eluted GS content using liquid chromatography – mass spectrometry (LCMS). We assessed the antibacterial activity of the obtained samples in vitro against various concentrations of MSSA (103–106 CFU/ml). Furthermore, we quantified the probability of bacterial colonization of UHMWPE impregnated with GS compared to GS containing bone cement. We assessed any detectable changes in activity of eluted GS caused by spacer fabrication by screening m/z peaks of GS isomers in mass spectra obtained from LC-MS.

Gentamicin sulfate activity was not compromised by the elevated temperature and pressure used during spacer fabrication. Elution rate of GS increased with increasing GS content in the blends studied. At comparable elution rates, the GS-loaded UHMWPE was either equivalent or better in terms of antibacterial and anticolonization properties when compared with gentamicin containing bone cement. GS-impregnated UHMWPE is a promising material for temporary spacers.

Introduction

Infection remains as one of the major challenges of total joint surgery. One-stage irrigation, debridement and reimplantation, or two-stage revision surgery with a temporary implantation of antibiotic eluting bone cement spacer followed by reimplantation are two methods often used to treat infected patients with mixed outcomes. Like bone cement, ultra-high molecular weight polyethylene (UHMWPE) can also be used as a carrier for antibiotics. Recently, we demonstrated that vancomycin and rifampin can be delivered from UHMWPE implants at therapeutic levels to eradicate Staphylococcus aureus biofilm in a lupine animal model. There are regulatory challenges in translating these types of combination devices to clinical use. Last year, at this meeting, we presented the preliminary pre-clinical testing for a temporary UHMWPE spacer containing gentamicin sulfate as a first step towards clinical use. Since then, we carried out a survey among the Knee Society membership about their preference for spacer use in two-stage revision surgery and found that 43% prefer to use a CoCr femoral component on an all-poly cemented tibial insert, 22% prefer bone cement spacers molded in the OR, 20% prefer static bone cement spacers, and 14% prefer pre-formed bone cement spacers. We modified our implant design based on the majority's preference for a total knee system, rather than bone cement spacers, in the temporary two-stage approach. In this study, we explored the effect of gentamicin sulfate (GS) elution from UHMWPE/GS tibial inserts on bacterial colonization on CoCr surfaces.

Aim

The effectiveness of mandatory joint aspiration prior to re-implantation in patients with a cement spacer already in place is unclear.

The aim of this study was to evaluate the role of culturing articular fluid obtained by joint aspiration prior to re-implantation in patients who underwent a two stage septic revision.

Aim

Septic arthritis of the hip is a rare entity among the adult population, but with a potential severe repercussion. The most accepted treatment is the hip debridement, even though a notorious proportion of the cases need further hip replacement owing to the cartilage destruction. The aim of this study is to analyse all our cases of septic arthritis of the hip treated with a 2-stage strategy using an antibiotic-loaded cement spacer.

Several risk factors can and should be addressed during first stage or spacer implantation surgery in order to minimize complications. Technical aspects as well as practical tips and pearls to overcome common nuisances such as spacer instability or femoral and acetabular bone loss will be discussed and shown with pictures.

Total joint arthroplasty (TJA) is one of the most successful procedures in orthopaedics and excellent results are expected in virtually all cases. Periprosthetic joint infection (PJI) though unusual, is one of the most frequent and challenging complications after TJA. It is the third most common cause of revision in total hip replacement, responsible for up to 15% of all cases.

In the past few years several improvements have been made in the management of an infected total hip prosthesis. Nevertheless it remains a challenging problem for the orthopaedic surgeon. Although numerous studies report favourable outcomes after one-stage revision surgery, two-stage has traditionally been considered as the gold standard for management of chronic infection. Two-stage exchange consists of debridement, resection of infected implants and usually temporary placement of an antibiotic-impregnated cement spacer before reimplantation of a new prosthesis.

Spacers can be classified as static or articulating. The goals of using an articulating antibiotic loaded cement spacer are two-fold: to enhance the clearance of infection by local antibiotic therapy and dead-space management while maintaining joint function during treatment thus improving the functional outcome at reimplantation. Still, hip spacer implantation is not innocuous and there are several possible complications.

Going forward, one must consider not just eradicating infection but also the importance of restoring function. In this regard using a mobile spacer adds an element of physiologic motion that both increases patient comfort between stages and facilitates re-implantation surgery. Conversely, mechanical complications are one of the major consequences of this preference. Be that as it may there are ways to minimize these problems. It is the surgeon responsibility to optimize mechanical circumstances as much as possible.

I would like to thank Dr. Ricardo Sousa for his help with this work