High-pressure saline washing of allografts reduces bacterial contamination

Effectiveness of a super-oxidized solution for decontaminating ACL grafts: a prospective study

BACKGROUND

Accidental contamination of anterior cruciate ligament (ACL) grafts during surgery is a relatively unexplored issue. This study aims to evaluate bacterial contamination in ACL grafts and the effectiveness of Microdacyn® in reducing contamination. The species of bacteria present on contaminated grafts and their antibiotic susceptibility were also analyzed.

METHODS

A total of 70 patients undergoing ACL reconstruction between 2019 and 2022 were included. Patients with prior knee surgery or immunodeficiency were excluded. Grafts were divided into three groups: (1) control (kept sterile), (2) contaminated (dropped on the operating room floor), and (3) rinsed (dropped and then decontaminated in Microdacyn®). Bacteriological examination and drug sensitivity tests were performed on all grafts. Statistical analysis was conducted using chi-square tests.

RESULTS

Grafts dropped on the floor showed a 74.3% (52 out of 70) contamination rate, with Staphylococcus epidermidis being the most commonly observed bacteria. After decontamination with Microdacyn®, 65.7% (46 out of 70) of the grafts were found sterile. The most sensitive antibiotics were trimethoprim + sulfamethoxazole, aztreonam and ceftazidime (97% effectiveness), while vancomycin, gentamicin, and meropenem were 95-96% effective.

CONCLUSIONS

While Microdacyn® reduced bacterial contamination, a significant portion of grafts remained contaminated, indicating that it is not fully effective. However, the bacteria found on the grafts showed high susceptibility to simple and inexpensive antibiotics, which did not contribute to increased resistance. Further studies exploring alternative decontamination methods are recommended to reduce the risk of complications from graft contamination during ACL reconstruction.

LEVEL OF EVIDENCE

II.

Experience with Tissue Bank Services in 2014 and 2020 in Turku, Finland

BACKGROUND

The objective of a musculoskeletal tissue bank is to collect, test, store, and provide musculoskeletal tissue allografts required in orthopedic procedures. Strict exclusion criteria are followed when selecting suitable cadaver musculoskeletal tissue donors, and the allografts are procured under sterile conditions to avoid bacterial contamination. Tissue banking in Turku, Finland, began in 1972, and tissue bank services were last reviewed in 2003. This study aimed to review the operation of the musculoskeletal tissue bank in Turku, Finland, between 2014 and 2020 and to analyze the number, types, and contamination rate of the allografts procured from the cadaver donors. Potential donor-related factors causing bacterial contamination of the allografts and whether potential musculoskeletal tissue donors were overlooked among multiorgan donors were also studied.

METHODS

A retrospective review of all cadaver musculoskeletal tissue donors used in the Hospital District of Southwest Finland Tyks Orto Musculoskeletal Tissue Bank during the study period was conducted, and data on the procured allograft was collected and presented. The donors were selected among patients treated in the intensive care unit (ICU) of Turku University Hospital (TYKS).

RESULTS

A total of 28 cadaver donors were used, and 636 allografts were procured between 2014 and 2020. The bacterial contamination rate was 2.5%, which was lower than that in the previous international literature. The median treatment time in the ICU was significantly longer, and the median value of the highest C-reactive protein level was significantly higher in the group of donors with positive allograft bacterial cultures.

CONCLUSIONS

The bacterial contamination rate in the tissue bank was low on an international scale. Some suitable musculoskeletal tissue donors were overlooked among multiorgan donors.

Uncemented Cups and Impaction Bone Grafting for Acetabular Bone Loss in Revision Hip Arthroplasty: A Review of Rationale, Indications, and Outcomes

Total hip arthroplasty (THA) is increasingly performed in young patients and the number of revisions is estimated to rise over time. Acetabular osteolysis and bone loss are frequently encountered during revision and may be classified and treated in different ways. Impaction bone grafting (IBG) with morselized allograft offers a viable option. IBG was introduced over 40 years ago in combination with cemented cups, and is also used with uncemented cups. The impacted bone chips act as a void filler to restore bone stock; once incorporated they are substituted by host bone. Surgery entails assessment of the defect, acetabular preparation, preparation of the morselized graft, impaction of the graft, and cup implantation. Satisfactory medium- and long-term results have now been reported in most studies. With the advent of high-porosity cups, indications have been extended, enhancing the potential of IBG, in which primary stability of the cup to the host bone is essential for a successful procedure. Synthetic bone substitutes have also been used in combination with allogenic grafts and may extend the original technique for which long-term studies are warranted.

Evaluating bacterial contamination of free bone fragments falling to the ground and the effectiveness of antiseptic solutions

OBJECTIVES

This study aims to determine the contamination incidence rate of bone fragments that have been dropped on the floor of the operating theatre, as well as how effective antimicrobial solutions are at decontaminating them.

METHODS

Bone fragments obtained after 30 total knee arthroplasties were used in the study. Inert pieces of bone emerging after the bone cuts during total knee arthroplasty were divided into 1 × 1 cm fragments. The bone fragments were first left in free fall on the floor of the operating theatre and then were kept in a number of antimicrobial solutions for 15 s. Subsequently, they were microbiologically and histopathologically examined. A swab culture was also taken from the floor of the operating theatre.

RESULTS

It was determined that 63.3% of osteochondral fragments in the non-intervened group were contaminated. Growth was likewise detected in all swab cultures. Microorganisms growing in the swab culture and the non-intervened group were similar and mostly Staphylococcus epidermidis and Klebsiella pneumoniae. When the growth rates of the 10% povidone-iodine and 4% chlorhexidine gluconate groups were compared with the growth rate of the non-intervened group, a statistical difference was found. No difference was determined between the growth rates of the sodium hypochlorite and the non-intervened groups. The histopathological analysis revealed no statistical difference between the groups in terms of bone marrow, vascular structure, fat tissue, and osteoblastic activity results in the osteochondral fragments CONCLUSION: Bone tissues dropped from a sterile area on the floor of the operating theatre are highly contaminated. An effective decontamination without bone cell toxicity was achieved using povidone-iodine. Although chlorhexidine gluconate solution had an effective decontamination effect compared to the non-intervened group, it was not 100% effective. Sodium hypochlorite solution was not effective in the decontamination of grafts under our working conditions.

Comparison of the Sterilization Efficiency of 3 Disinfectants for Dropped Anterior Cruciate Ligament Grafts: A Systematic Review and Meta-analysis

Background:

The inadvertent contamination of anterior cruciate ligament (ACL) grafts can occur if they are accidentally dropped on the floor during ACL reconstruction. There has been no meta-analysis conducted to compare the sterilization efficiency of the different disinfectants used on dropped ACL grafts.

Purpose:

To compare the sterilization efficiency of 3 disinfectants to decontaminate ACL grafts as necessary.

Study Design:

Systematic review.

Methods:

A systematic literature review was performed using the MEDLINE, Embase, and Cochrane Library databases. All studies reporting the management of dropped or contaminated grafts were considered for this meta-analysis.

Results:

A total of 7 studies meeting inclusion criteria were identified from a literature search. The pooled results of this meta-analysis indicated that the rate of positive cultures of ACL grafts dropped on the operating room floor was 44.9% and that the commonly contaminated microbes were staphylococci and bacilli. The meta-analysis results indicated that the sterilization efficiency of a 4% chlorhexidine solution was superior to an antibiotic solution (odds ratio [OR], 0.17 [95% CI, 0.05-0.57]; P = .004) and a 10% povidone-iodine solution (OR, 0.04 [95% CI, 0.01-0.20]; P < .0001). Further, the antibiotic solution was superior to the 10% povidone-iodine solution (OR, 0.20 [95% CI, 0.07-0.55]; P = .002).

Conclusion:

The results of our meta-analysis demonstrated that staphylococci and bacilli were the most common contaminants on dropped ACL grafts and that decontamination using a 4% chlorhexidine solution more reliably disinfected ACL grafts. This information can help to guide surgeons as regards appropriate remedial measures.

Quantification Analysis of the Intraoperative Bacterial Contamination Rate and Level in Osteochondral Autografts

BACKGROUND

Inadvertent contamination of osteochondral (OC) autografts during harvesting and preparation can lead to significant complications and can cause the operating team to weigh the infection risk after reimplantation against discarding the OC fragment. The most commonly reported contamination mechanism is the accidental dropping of an OC fragment; however, associated contamination levels remain unclear. The rate and level of contamination during standard harvesting and preparation are also unknown.

PURPOSE

To quantitatively evaluate the rate and level of bacterial contamination of OC autografts during harvesting and preparation compared with those of accidently dropped autografts.

STUDY DESIGN

Controlled laboratory study.

METHODS

Under sterile conditions, 138 fresh OC specimens were harvested and retrieved from 23 primary total knee arthroplasties (TKAs). Six OC fragments were retrieved from each TKA: 3 were used as controls, and 3 were dropped onto the operating room floor. Each specimen was incubated to allow for aerobic and anaerobic growth, and the number of colony-forming units (CFUs) per gram was calculated.

RESULTS

Contamination rates (positive cultures) for the control and dropped groups were 29% (n = 20/69) and 42% (n = 29/69), respectively. The difference in the contamination rate between groups was not statistically significant (P = .109). The most common organisms identified were Staphylococcus aureus (40%) in the control group and Staphylococcus epidermidis (24.1%) and Bacillus species (20.7%) in the dropped group. The contamination level (CFUs/g) for both groups was low. The median (range) CFUs/g among the contaminated specimens in the dropped and control groups were 27 (1-120) and 3 (1-15), respectively (P < .0001).

CONCLUSION

A relatively high rate of OC autograft contamination can be expected during harvesting and preparation (29%) or after accidentally dropping a specimen (42%). Although the types of organisms isolated differed between specimens contaminated during harvesting and preparation and dropped specimens, the quantification of the autograft contamination level revealed a very low CFUs/g in both cases.

CLINICAL RELEVANCE

The intraoperative autograft contamination level is very low. Hence, in cases of grafts with a known contamination incident, saving and reimplanting them after proper decontamination is recommended over discarding them or using an allograft.

Acetabular reconstruction with impaction bone grafting and cemented polyethylene socket in total hip revision arthroplasty

Background and aims:

Bone deficiency in revision total hip arthroplasty is a challenge to the surgeon. One option for restoration of the bone stock is impaction bone grafting and use of a cemented socket. The aim of this study was to evaluate the mid-term clinical outcome of impaction bone grafting and cemented socket revisions.

Material and methods:

A total of 59 patients (60 hips) underwent revision arthroplasty with impaction bone grafting and application of a cemented socket on the acetabular side in the Turku University Hospital from 1999 to 2004. The study end-point was re-revision for any reason. The cumulative percentages for survival were followed and estimated with Kaplan–Meier curves. Associations between occurrence of re-revision and potential risk factors were analyzed with logistic regression. Results were quantified by odd ratios and 95% confidence intervals. The mean age of the patients was 69 years (33% male). A total of 3% of the patients had a class I Paprosky acetabular defect, 38% had class II, and 55% had class III.

Results:

The overall survival rate was 73%. The mean follow-up time was 7 years. The most common reason for re-revision was aseptic loosening of the acetabular component (13 patients, 81% of re-revisions). Cox’s regression analysis did not identify any risk factors for re-revision.

Conclusion:

Our results were inferior compared to some previous studies. Impaction bone grafting of acetabular defects in revision total hip arthroplasty may not always provide a reliable bone stock in long-term.

Allografts in soft tissue reconstructive procedures: important considerations

CONTEXT

Allografts offer several important advantages over autografts in musculoskeletal reconstructive procedures, such as anterior cruciate ligament reconstruction. Despite growing widespread use of allograft tissue, serious concerns regarding safety and functionality remain. We discuss the latest knowledge of the potential benefits and risks of allograft use and offer a critical review of allograft tissue regulation, management, and sterilization to enable the surgeon to better inform athletes considering reconstructive surgery options.

EVIDENCE ACQUISITION

A review of sources published in the past 10 years is the primary basis of this research.

STUDY DESIGN

Observational analysis (cohort study).

LEVEL OF EVIDENCE

Level 3.

RESULTS

Comparable outcome data for autografts and allografts do not support universal standards for anterior cruciate ligament reconstruction, and physician recommendation and bias appear to significantly influence patient preference and satisfaction. Sterilization by gamma and electron-beam irradiation diminishes the biomechanical integrity of allograft tissue, but radioprotective agents such as collagen cross-linking and free radical scavengers appear to have potential in mitigating the deleterious effects of irradiation and preserving tissue strength and stability.

CONCLUSION

Allografts offer greater graft availability and reduced morbidity in orthopaedic reconstructive procedures, but greater expansion of their use by surgeons is challenged by the need to maintain tissue sterility and biomechanical functionality. Advances in the radioprotection of irradiated tissue may lessen concerns regarding allograft safety and structural stability.

Are dropped osteoarticular bone fragments safely reimplantable in vivo?

BACKGROUND

There are limited data detailing the appropriate management of nondisposable autologous osteoarticular fragments that have been contaminated by the operating room floor. The goal of the present study was to perform a comprehensive, three-phase investigation to establish an appropriate intraoperative algorithm for the management of the acutely contaminated, but nondisposable, autologous osteoarticular bone fragment.

METHODS

Phase I of the study was performed to quantify the rate of contamination and microbial profile of human osteoarticular fragments that were dropped onto the operating room floor (n = 162). Phase II was performed to assess the feasibility and optimal means of decontaminating 340 similar fragments that underwent controlled contamination with bacteria that were identified in Phase I; decontamination was performed with use of cleansing agents that are routinely available in an operating room. Phase III was performed to assess the effect of each decontamination process on fragment chondrocyte viability through histologic evaluation.

RESULTS

The contamination rate in Phase I was 70%. Coagulase-negative Staphylococcus was the most commonly cultured organism. In Phase II, varying exposure time to the chemical agents did not make a significant difference in decontamination rates. Mechanical scrubbing was superior to mechanical saline solution lavage (zero of fifty-six cultures compared with twenty of fifty-six cultures were positive for coagulase-negative Staphylococcus; p < 0.001). As a whole, bactericidal agents were found to be more effective decontaminating agents than normal saline solution. Povidone-iodine and 4% chlorhexidine gluconate were the most effective decontaminating agents, with none of the twenty-eight specimens that were decontaminated with each agent demonstrating positive growth on culture. Phase III demonstrated that the groups that were treated with normal saline solution and povidone-iodine retained the greatest number of live cells and the least number of dead cells. Mechanical scrubbing significantly decreased chondrocyte viability as compared with a normal saline solution wash (p < 0.05).

CONCLUSIONS

The majority of osteochondral fragments that contact the operating room floor produce positive bacterial cultures. Five minutes of cleansing with a 10% povidone-iodine solution followed by a normal saline solution rinse appears to provide the optimal balance between effective decontamination and cellular toxicity for dropped autologous bone in the operative setting.

Intra-operative washing of morcellised bone allograft with pulse lavage: how effective is it in reducing blood and marrow content?

The use of unprocessed bone carries a risk of transmission of blood borne diseases. Although models of infectivity are unproven, a theoretical risk of transmission of variant Creutzfeld-Jakob Disease, a human prion disease, exists as probable blood borne transmission has been reported in three cases. The aim of our study was to determine the effectiveness of standard operating theatre pulse lavage in removing protein, fat and double stranded Deoxyribonucleic acid (dsDNA) from morcellised bone allograft. Twelve donated femoral heads were divided into halves and milled into bone chips. One half of the bone chips were washed with pulse lavage, whereas, the other half acted as control. In order to determine the amount of protein, fat and dsDNA present in the washed and unwashed samples, a validated multistep washing protocol was used. Using the validated technique, simple intra-operative washing of morcellised unprocessed bone allograft removed a significant amount of the protein (70.5%, range: 39.5-85%), fat (95.2%, range: 87.8-98.8%) and DNA (68.4%, range: 31.4-93.1%) content. Intra-operative washing of morcellised bone allograft with pulse lavage may thereby reduce the theoretical risk of prion and other blood borne disease transmission. Combined with the known improved mechanical characteristics of washed allograft, we would recommend pulse lavage as a routine part of bone allograft preparation.

Pulse-lavage washing is an effective method for defatting of morselized allograft bone in the operating theater

BACKGROUND AND PURPOSE

Incorporation of fresh-frozen allograft bone and safety aspects associated with this procedure can be improved by removing blood and lipids from the bone. We investigated in a quantitative manner how efficient pulse lavage might be for removal of adipose tissue from morselized allograft bone.

METHODS

Depending on the study, the washing was performed with an average of 0.8 L or 1.6 L of sterile saline at room temperature. Fat content of the morselized bone samples was determined using hexane elution. The efficiency of pulse lavage alone was compared with that after an additional wash in 12 L of warm water (55 degrees C). Unprocessed controls were also included for comparison.

RESULTS

Pulse lavage with 0.8 L saline alone removed 80% of the fat from the bone, whereas 95% of the fat was removed when washing was performed with 1.6 L of saline. The cleansing efficacy was improved further when an additional wash with warm water was used.

INTERPRETATION

Our results indicate that pulse-lavage washing alone at room temperature is an effective method for defatting of morselized allograft bone, but an additional wash with warm water improves the cleansing efficiency. Pulse lavage is easily available and simple to use in the operating theater.

Biological effects of rinsing morsellised bone grafts before and after impaction

Rinsing bone grafts before or both before and after impaction might have different effects on the incorporation of the graft. Rinsing again after impaction might negatively influence bone induction if growth factors released by impaction are washed away. We studied if transforming growth factor-betas (TGF-betas) and bone morphogenetic proteins (BMPs) are released from the mineralised matrix by impaction and if these released growth factors induce osteogenic differentiation in human mesenchymal stem cells (hMSCs). Rinsed morsellised bone allografts were impacted in a cylinder and the escaping fluid was collected. The fluid was analysed for the presence of TGF-betas and BMPs, and the osteoinductive capacity was tested on hMSCs. Abundant TGF-beta was present in the fluid. No BMPs could be detected. Osteogenic differentiation of hMSCs was inhibited by the fluid. Results from our study leave us only able to speculate whether rinsing grafts again after impaction has a beneficial effect on the incorporation process or not.

Allograft update: the current status of tissue regulation, procurement, processing, and sterilization

Allografts are commonly used during sports medicine surgical procedures in the United States, and their frequency of use is increasing. Based on surgeon reports, it is estimated that more than 60 000 allografts were used in knee surgeries by members of the American Orthopaedic Society for Sports Medicine in 2005. In the United States, there are governmental agencies and other regulatory bodies involved in the oversight of tissue banks. In 2005, the Food and Drug Administration finalized its requirements for current good tissue practice and has mandated new rules regarding the "manufacture" of allogenic tissue. In response to well-publicized infections associated with the implantation of allograft tissue, some tissue banks have developed methods to sterilize allograft tissue. Although many surgeons have significant concerns about the safety of allografts, the majority believe that sterilized allografts are safe but that the sterilization process negatively affects tissue biology and biomechanics. However, most know very little about the principles of sterilization and the proprietary processes currently used in tissue banking. This article will review the current status of allograft tissue regulation, procurement, processing, and sterilization in the United States.

Overview of safety issues concerning the preparation and processing of soft-tissue allografts

With the increasing use of allograft tissue and the recent infections found in patients undergoing surgical procedures, the current practices that prepare grafts for implantation must be examined. Initially, most tissue banks harvest allografts aseptically. There are many steps in the different techniques of preparation and processing of allograft tissue. Before allograft tissue is ready for clinical use, it undergoes specific disinfection methods, according to the individual tissue bank's specific process. Tissue banks use in-process bactericidal and virucidal steps via physical cleaning, chemical treatments, or application of irradiation to the allografts (or some combination thereof). Gamma irradiation may also be used as a terminal processing method to reach an assurance of sterility after the allograft has been packaged. Because of the allograft toxicity potential, the use of ethylene oxide as a final tissue sterilization measure is really nonexistent. The role of the Food and Drug Administration and American Association of Tissue Banks in allograft tissue handling is presented, as well as the new rules that regulate tissue banks and affect their processing methods.

High-pressure irrigation and gentian-violet application for mediastinitis following replacement of ascending aorta and aortic valve

Mediastinitis following ascending aortic replacement is intractable and potentially fatal, and the feature is characterized as having both high mortality and morbidity when its causation pathology is methicillin-resistant Staphylococcus aureus (MRSA). Possible treatments for the condition, which include debridement, irrigation, and healthy tissue transposition, often result in failure. We report a case of MRSA mediastinitis after replacement of the ascending aorta and the aortic valve successfully treated by continuous saline lavage and drainage, debridement, high-pressure irrigation, and gentian-violet application, and delayed omental-flap transposition. The application of gentian violet and high-pressure irrigation may provide an additional option to the standard therapy for intractable mediastinitis after ascending aortic replacement.

Lipid oxidation may reduce the quality of a fresh-frozen bone allograft. Is the approved storage temperature too high?

BACKGROUND

International standards indicate that bone allografts for human use should be stored in a -40 degrees C or colder environment and the storage time should be up to 5 years. Bone allografts contain lipids which oxidate and become toxic with time.

MATERIAL AND METHODS

We determined lipid oxidation in femoral head bone allografts by headspace gas chromatography at different storage temperatures and storage times.

RESULTS

We found that lipid oxidation in fresh-frozen bone allograft was influenced by storage temperature and storage time. Lipid oxidation was significantly more rapid at -30 degrees C than at -70 degrees C. Even at -70 degrees C, however, some oxidation occurred but it was quite minimal after 3 years.

INTERPRETATION

Because of the negative effects of lipid oxidation, we recommend a storage temperature of -70 degrees C or lower for bone allografts.

Larger bone graft size and washing of bone grafts prior to impaction enhances the initial stability of cemented cups: experiments using a synthetic acetabular model

BACKGROUND

Bone defects after failed total hip arthroplasty can be reconstructed with impacted morselized bone grafts and a cemented cup. On the acetabular side, the effects on initial cup stability of washing bone grafts prior to impaction and bone graft size remain unclear. Related to these variables, cement penetration and inter-particle shear resistance have been suggested to be critical factors to ensure initial cup stability.

METHODS

Using a synthetic acetabular model, we studied the effects of (1) washing bone grafts prior to impaction, and (2) bone graft size on the initial stability of cemented cups. In addition, cement penetration was measured using CT scans.

RESULTS

Reconstructions with large, washed bone grafts provided the highest stability during mechanical compression and in a lever-out situation. Washing of the bone grafts had a positive effect on initial cup stability, but the size of the bone grafts appeared to be more important. Cement penetration was affected by bone graft size but not by washing.

INTERPRETATION

From a mechanical standpoint, large bone grafts that have been washed prior to impaction may be preferable in order to obtain optimal cup stability using the bone impaction grafting technique.

Spacer prostheses in two-stage revision of infected knee arthroplasty

At present, no consensus exists on the best spacer alternative for the management of two-stage exchange arthroplasty of infected knee arthroplasties. In this retrospective study, patient records of 24 patients, who had undergone two-stage revisions in which resterilised prosthetic components were used as spacers, were reviewed. The outcome was compared to that of operations performed during the same period (1993-2003) using cement spacers (n=10). With an average follow-up of 32 months, control of infection was achieved in 26 cases (76%), with good or excellent clinical outcome in 19 cases (56%). Treatment failed and resulted in amputation at the level of the thigh before reimplantation in one case. Three patients did not undergo reimplantation. In four cases (12%) infection relapsed. The reinfection rate did not differ between the two spacer groups. Patients treated with resterilised components had a superior range of motion during the period between the two stages. Operative time was shorter and there was less blood loss in the reimplantation arthroplasty when a prosthetic spacer was used. We consider resterilised prosthetic components a safe and effective alternative to cement spacers in the management of infected knee arthroplasties.

Incidence of infection with the use of non-irradiated morcellised allograft bone washed at the time of revision arthroplasty of the hip

Implantation of allograft bone is an integral part of revision surgery of the hip. One major concern with its use is the risk of transmission of infective agents. There are a number of methods of processing allograft bone in order to reduce this risk. One method requires washing the tissue using pulsed irrigation immediately before implantation. We report the incidence of deep bacterial infection in 138 patients (144 revision hip arthroplasties) who had undergone implantation of allograft bone. The bone used was fresh-frozen, non-irradiated and pulse-washed with normal saline before implantation. The deep infection rate at a minimum follow-up of one year was 0.7%. This method of processing appears to be associated with a very low risk of allograft-related bacterial infection.

Contaminant seeding in bone by different irrigation methods: an experimental study

OBJECTIVE

This study was designed to investigate the effectiveness of using various devices and manual procedures for cleansing bacterially contaminated bone tissue and to assess the risk of iatrogenic bacterial seeding in deep bone layers.

METHODS

In an in vitro model, human femoral heads were contaminated with Escherichia coli and then cleansed with pulsatile high-pressure lavage, pulsatile low-pressure lavage, manual rinsing with bulb syringe lavage, or manual rinsing with combined brush cleaning. The numbers of bacteria that remained or those that were introduced by the rinsing procedures were quantitatively determined at depths of 0 to 1 cm, 1 to 2 cm, and 2 to 3 cm.

RESULTS

Both pulsatile high-pressure lavage and brush cleaning were more effective than pulsatile low-pressure lavage and bulb syringe lavage for the purpose of surface cleansing. The differences were highly significant (P < 0.001). There was no significant difference in the decontaminating effect between pulsatile high-pressure lavage and brush cleaning (P = 0.24). The bacterial contamination attributable to the cleansing procedure, as measured at tissue depths of 1 to 2 cm and 2 to 3 cm, was significantly higher after pulsatile high-pressure lavage and after pulsatile low-pressure lavage than it was after bulb syringe lavage or brush cleaning (P < 0.001).

CONCLUSION

In this in vitro investigation of cancellous bone, the brush cleansing was just as effective for getting rid of bacterial contamination as pulsatile high-pressure lavage, and carries a significantly lesser risk of iatrogenic bacterial seeding into deeper tissue layers. In the light of these promising results obtained by the cleansing of cancellous bone contaminated with bacteria, it would be desirable to perform supplementary in vitro and in vivo investigations into brush cleansing.

High-pressure pulsatile lavage propagates bacteria into soft tissue

Initial wound treatment is critical in the treatment of open fractures, contaminated wounds, and abscesses. Ample evidence suggests that high-pressure pulsatile lavage damages bone structure and disrupts soft tissue. We compared the depth of penetration and amount of retention of bacteria in contaminated soft tissue subjected to one of two lavage methods: high-pressure pulsatile and low-pressure gravity flow. Fresh ovine muscle was harvested, contaminated with fluorescently stained Staphylococcus aureus, and subjected to lavage treatment. Specimens in each lavage method group were subdivided based on orientation across or in line with the muscle fibers. High-pressure lavage causes increased depth of bacterial penetration (across: 3,835 microm; in line: 4,220 microm) when compared with low-pressure lavage (across: 1,680 microm; in line: 2,095 microm). Furthermore, both high-pressure treatment groups had higher numbers of retained bacteria as counted in 50 mum x 7,500 microm x 5 microm sections of tissue after lavage (across: 197; in line: 188) when compared with the low-pressure groups (across: 94; in line: 40). These results show that high-pressure pulsatile lavage causes deeper penetration of bacteria and results in greater bacterial retention in soft tissue when compared with low-pressure lavage.

Cortical allograft as a vehicle for antibiotic delivery

BACKGROUND

Infection can be a devastating complication after implantation of a cortical bone allograft. The allograft could act as a vehicle for local antibiotic prophylaxis.

MATERIAL AND METHODS

We studied the release of antibiotics in vitro from cortical bone allografts impregnated with antibiotics for different periods of time. We also studied whether cortical allografts impregnated with antibiotics could eradicate Staphylococcus aureus from an experimentally infected graft in vivo. In the in vitro study, pieces of cortical bone were impregnated with netilmicin, vancomycin, ciprofloxacin and rifampicin for 1 h, 10 h and 100 h. The antibiotics were eluted into phosphate-buffered saline (PBS) for 7 days, with daily transfer of the bone into fresh PBS. In the in vivo study, cortical allografts impregnated with antibiotics were placed in rats intramuscularly. 10 microL of an S. aureus suspension (0.6 x 10(5) CFU) was placed in the intramedullary cavity. After 15 days, the allografts were removed and examined for bacterial growth.

RESULTS

The amount of antibiotics released in vitro was influenced by the time used for antibiotic impregnation of the bone. Allografts impregnated with netilmicin, vancomycin and rifampicin effectively eradicated perioperative contamination with S. aureus in vivo.

INTERPRETATION

This study shows that a cortical bone allograft would be an effective vehicle for local antibiotic delivery.

Cefuroxime, rifampicin and pulse lavage in decontamination of allograft bone

The risk of bacterial infection through allogenic bone transplantation is one of the major problems facing tissue banks. Different screening methods and decontamination procedures are being used to achieve a safe surgical result. The purpose of this study was to investigate the contamination rate in fresh frozen bone allografts after treating them with different decontamination methods. The allografts were contaminated by rubbing on the operating theatre floor for 60 min, after which they were rinsed either with sterile physiological saline, cefuroxime or rifampicin solution or they were washed with low-pressure pulse lavage of sterile physiological saline. Our findings show that low-pressure pulse lavage with sterile saline solution is very effective in removing bacteria from bone allograft, when compared with the antibiotic solutions tested.

The safe and effective use of allograft tissue--an update

The use of allograft tissue in orthopaedic surgery has increased tremendously over the last several years. Tissue availability, reduced surgical times, and lack of donor site morbidity are attractive characteristics to surgeons and patients alike. Although complications, such as disease transmission, are relatively uncommon when using allograft tissue, they do occur. This article will review the literature concerning the safe and effective use of allograft tissue, as well as present four case reports of Clostridium septicum infection caused by implantation of contaminated allograft tissue.