Osteoarticular Mycoses

Osteoarticular mycoses are chronic debilitating infections that require extended courses of antifungal therapy and may warrant expert surgical intervention. As there has been no comprehensive review of these diseases, the International Consortium for Osteoarticular Mycoses prepared a definitive treatise for this important class of infections. Among the etiologies of osteoarticular mycoses are Candida spp., Aspergillus spp., Mucorales, dematiaceous fungi, non-Aspergillus hyaline molds, and endemic mycoses, including those caused by Histoplasma capsulatum, Blastomyces dermatitidis, and Coccidioides species. This review analyzes the history, epidemiology, pathogenesis, clinical manifestations, diagnostic approaches, inflammatory biomarkers, diagnostic imaging modalities, treatments, and outcomes of osteomyelitis and septic arthritis caused by these organisms. Candida osteomyelitis and Candida arthritis are associated with greater events of hematogenous dissemination than those of most other osteoarticular mycoses. Traumatic inoculation is more commonly associated with osteoarticular mycoses caused by Aspergillus and non-Aspergillus molds. Synovial fluid cultures are highly sensitive in the detection of Candida and Aspergillus arthritis. Relapsed infection, particularly in Candida arthritis, may develop in relation to an inadequate duration of therapy. Overall mortality reflects survival from disseminated infection and underlying host factors.

Adjuvant antibiotic-loaded bone cement: Concerns with current use and research to make it work

Antibiotic-loaded bone cement (ALBC) is broadly used to treat orthopaedic infections based on the rationale that high-dose local delivery is essential to eradicate biofilm-associated bacteria. However, ALBC formulations are empirically based on drug susceptibility from routine laboratory testing, which is known to have limited clinical relevance for biofilms. There are also dosing concerns with nonstandardized, surgeon-directed, hand-mixed formulations, which have unknown release kinetics. On the basis of our knowledge of in vivo biofilms, pathogen virulence, safety issues with nonstandardized ALBC formulations, and questions about the cost-effectiveness of ALBC, there is a need to evaluate the evidence for this clinical practice. To this end, thought leaders in the field of musculoskeletal infection (MSKI) met on 1 August 2019 to review and debate published and anecdotal information, which highlighted four major concerns about current ALBC use: (a) substantial lack of level 1 evidence to demonstrate efficacy; (b) ALBC formulations become subtherapeutic following early release, which risks induction of antibiotic resistance, and exacerbated infection from microbial colonization of the carrier; (c) the absence of standardized formulation protocols, and Food and Drug Administration-approved high-dose ALBC products to use following resection in MSKI treatment; and (d) absence of a validated assay to determine the minimum biofilm eradication concentration to predict ALBC efficacy against patient specific micro-organisms. Here, we describe these concerns in detail, and propose areas in need of research.

Lytic Lesion in the Proximal Humerus After a Flu Shot: A Case Report

CASE

There has been a recent campaign to vaccinate patients in an effort to prevent widespread flu pandemic. Although the complication rate after vaccine is low, there have been reports of Guillain-Barré syndrome and shoulder injury related to vaccine administration (SIRVA). In this case presentation, we discuss a patient who developed a large lytic lesion in the proximal humerus after a deeply administered flu shot.

CONCLUSIONS

SIRVA is a rare cause of shoulder pain after injections, but one that progresses and often necessitates operative management. Clinicians should be wary of persistent shoulder pain after a flu shot.

390. Treatment and Outcome of Methicillin-Resistant Staphylococcus aureus Hip and Knee Prosthetic Joint Infection

Background

Methicillin-resistant Staphylococcus aureus (MRSA) total hip and knee prosthetic joint infections (PJI) can be highly morbid and difficult to treat. Other clinical factors notwithstanding, explantation is usually recommended, although comparative treatment data are lacking. We sought to compare the success of implant retention to two-stage exchange in MRSA-infected PJI to better understand treatment options in this difficult cohort.

Methods

A retrospective cohort of hip and knee PJIs from 2009 to 2016 were identified by ICD code and surgical treatment. All cases met MSIS criteria for PJI, and had culture-confirmed MRSA from synovial or intra-articular tissue culture. PJIs were either treated with exchange arthroplasty or debridement with antibiotic and implant retention (DAIR). Success was defined as no further surgical treatment for infection at two years. Kaplan–Meier estimates were used to calculate the 2-year survival rate free from treatment failure. Univariate logistic regression was performed to identify risk factors associated with treatment failure.

Results

65 MRSA PJIs were identified with 42 undergoing explantation and 23 undergoing DAIR. Demographics, Charlson comorbidities, infection type (early post-operative, hematogenous or late chronic), and history of prior PJI were not significantly different between treatment groups. Survivorship at two years was 75% (95% confidence interval [CI] 61–88%) for exchange compared with 29% (95% CI 10–48%) for DAIR, P = 0.0002. Within the exchange group, knee PJIs were more likely to fail than hip PJI (odds ratio [OR] 7.1, CI 1.3–38, P = 0.02), and patients with diabetes were more likely to fail (OR 17, CI 1.6–178, P = 0.02).

Conclusion

MRSA PJIs treated with DAIR have worse outcomes than those treated with prosthesis exchange. Further investigation is needed to identify predictors of DAIR success, to optimize surgical treatment choice, and to improve outcomes of these difficult infections.

Disclosures

All authors: No reported disclosures.

321. Assessing the Role of Daptomycin as Antibiotic Therapy for Staphylococcal Prosthetic Joint Infection

Background

Methods

Results

Conclusion

Disclosures

311. Low Rate of Microbiologic Relapse in Two-Stage Exchange for Knee Prosthetic Joint Infections

Background

Prosthetic joint infection (PJI) is a grave complication of total knee arthroplasty (TKA). Historically, two-stage arthroplasty exchange has been considered to be the definitive approach to eradicating infection and preserving joint function. However, patients are increasingly presenting with higher rates of comorbidities traditionally associated with poorer orthopedic surgical outcome, including advanced age, obesity and diabetes. We investigated whether two-stage exchange remains effective for TKA PJI in this population, and evaluated the microbiology of repeat infections.

Methods

A retrospective cohort of TKA PJI treated with two-stage exchange was identified by query of hospital coding records from 2009 to 2014, with subsequent chart review. The primary endpoint was defined as prosthesis retention for 2 years from reimplantation. Microbiologic relapse was defined as a recurrence of a previously treated organism. Descriptive statistics were completed using the Fisher’s exact test for categorical variables and the Mann–Whitney U test for continuous variables.

Results

One hundred fifty-nine patients who underwent two-stage exchange for a TKA PJI meeting Musculoskeletal Infection Society International Consensus criteria were identified. The average age was 66 years, and 37% were female. One hundred forty-one underwent reimplantation; 24 of these (17%) had recurrent infection. Of the 24 patients who developed infection after reimplantation, only four relapsed with the same microbe; the other 20 (83%) were diagnosed with new, microbiologically distinct organisms. Thee of these four recurrences were due to Staphylococcus aureus infection. The likelihood of microbiologic relapse was low among reimplanted patients (3%). In univariate analysis, no associations were found between outcome and age, comorbidities, or BMI.

Conclusion

Two-stage exchange arthroplasty for TKA infection is associated with a very low rate of microbiologic relapse. However, those patients able to undergo reimplantation remain at risk of subsequent infections with new microbes. It remains important to continue to modify risk factors in patients who have undergone a two-stage exchange for PJI.

Disclosures

All authors: No reported disclosures.

309. The Infected Spacer: The Impact of Spacer Exchanges and Debridements on Two-Stage Exchange Arthroplasty Outcomes

Background

Prosthetic joint infection (PJI) is a grave complication of total joint arthroplasty (TJA). Data on patients who require further surgery for infection between explantation and reimplantation (i.e., while the spacer is in place) are limited. We investigated the effect of spacer exchange or irrigation and debridement (I&D) on clinical outcomes in patients undergoing two-stage exchange for PJI.

Methods

A retrospective cohort of hip and knee PJI treated with two-stage exchange was identified by query of hospital coding records from 2009 to 2014, with subsequent chart review. All cases met Musculoskeletal Infection Society International Consensus criteria for PJI. The primary endpoint was defined as prosthesis retention for 2 years from reimplantation. Spacer intervention was defined as undergoing a spacer exchange or I&D for infection purposes prior to reimplantation. Descriptive statistics were completed using the Fisher’s exact test for categorical variables and the Mann–Whitney U test for continuous variables.

Results

Three hundred patients undergoing two-stage exchange for TJA PJI were identified (141 hips and 159 knees). The average age was 66 years and 42% were female. Forty-two patients (14%) underwent spacer intervention, 22 knees (14%), and 20 hips (14%). 34 of these underwent spacer exchange. Of the 42 patients with spacer intervention, 28 (67%) met the primary endpoint. In univariate analysis, there was an association between spacer intervention and outcome (P = 0.02). Comorbidities including age, sex, and BMI were not associated with outcome. The association appeared more pronounced among the TKA subgroup. Patients who underwent spacer intervention were 2.1[CI: 1.11–4.42] times more likely to fail than TKA patients who did not require such an intervention (P = 0.02).

Conclusion

We present 2-year outcomes on a large cohort of TJA PJI treated with two-stage exchange arthroplasty. Patients requiring spacer exchange or I&D after TJA explantation have worse outcomes than their counterparts who do not. Because patients who fail two-stage exchange arthroplasties often proceed to arthrodesis or amputation, our findings may help guide clinical decision-making prior to reimplantation.

Disclosures

All authors: No reported disclosures.

Low Rate of Microbiologic Relapse in Two-Stage Exchange for Hip Prosthetic Joint Infections

Background

Prosthetic joint infection (PJI) is a grave complication of total hip arthroplasty (THA). Historically, two-stage arthroplasty exchange has been considered to be the definitive approach to eradicating infection and preserving joint function. However, patients are increasingly presenting with higher rates of comorbidities traditionally associated with poorer orthopedic surgical outcome, including advanced age, obesity and diabetes. We investigated whether two-stage exchange remains effective for THR PJI at an orthopedic specialty hospital, and what were the microbiologic etiologies in repeat infections.

Methods

A retrospective cohort of THA PJI treated with two-stage exchange was identified by query of hospital coding records from 2009 to 2014. The primary endpoint was defined as 2-year implant retention without further surgery. Failure was defined as a recurrence within in 2 years. Microbiologic failure was defined as a recurrence of the previously treated organism. Descriptive statistics were completed using the Fisher’s exact test for categorical variables and the Mann–Whitney U-test for continuous variables.

Results

One hundred and forty-four patients meeting Musculoskeletal Infection Society International Consensus criteria for THA PJI were identified. The average age was 65 years and 60% were female. One hundred and twenty-seven (88.2%) were cured at 2 years. Pathogens included Staphylococcus aureus (MSSA, 23%; MRSA, 13%), coagulase-negative staphylococci (17%), and streptococci (17%). In univariate analysis, no links were noted between primary outcome and patient age, comorbidities (including diabetes and tobacco), BMI, microbiology, or symptom duration. Of the 17 patients who did not meet criteria for success, 11 (65%) were diagnosed with new, microbiologically distinct infection. The remaining six met our criteria for microbiologic failure; four of the six patients had S. aureus infection (three MSSA).

Conclusion

We present 2-year outcomes on a large cohort of THA PJI treated with two-stage exchange arthroplasty. Nearly, two-thirds of the patients who failed were found to have a new infection at the time of relapse. Only 4% of the patients in our cohort failed to achieve cure of the primary infection. Two-stage exchange continues to be an effective approach to PJI treatment with a low rate of microbiologic failure.

Disclosures

All authors: No reported disclosures.

The Influence of Obesity on the Infection Risk of Prosthetic Joint Infection in the Geriatric Orthopedic Population

Background

Prosthetic joint infection (PJI) is a dreaded complication of arthroplasty. PJI are more common in the elderly and are associated with a substantial increase in 5-year mortality risk. PJI risk may correlate with increasing body mass index (BMI). However, the effect of BMI on PJI risk in the elderly has not been evaluated, to our knowledge. We sought to evaluate this relationship in a cohort of geriatric arthroplasty patients at an orthopedic specialty hospital.

Methods

A retrospective cohort of hip and knee arthroplasty patients (age >75) from 2009–2014 was identified through administrative hospital data using ICD-9 codes. Patients with a BMI <14 or >60 kg/m², height <142 or >200 cm, and weight <36 or >226 kg were excluded. The presence of infection was confirmed via chart review; all PJIs met MSIS criteria. Obesity was defined as having a BMI >30. Univariate analyses were done using χ ² tests and adjusted models were assessed using logistic regression.

Results

13,755 geriatric arthroplasty patients (6,408 total hip arthroplasties [THA] and 7,347 total hip arthroplasties [TKA]) were assessed. Mean age and BMI were 82 (±5.4) and 28.1 (±5.3), respectively. In an unadjusted model, obesity was associated with infection in THA (P = 0.02), but not TKA (P = 0.31). This association remained after adjusting for age, sex, and diabetes. Obesity was associated with an increased risk of infection in THA [OR=1.89 (95% CI 1.12–3.21); P = 0.02]. However, as with the unadjusted model, this relationship was not found in TKA (P = 0.50).

Conclusion

Obesity increases THR PJI risk in the elderly. However, no such association was found for TKA. Future studies are needed to quantify the compounded risk of obesity in the geriatric arthroplasty patient.

Disclosures

All authors: No reported disclosures.

Reexamining BSA as a Preoperative Predictor of Risk of Prosthetic Joint Infection

Background

Prosthetic joint infection (PJI), a dreaded complication of arthroplasty, has been found to correlate with increasing body mass index (BMI) and body surface area (BSA). Recent data suggest that BSA may be a better predictive tool for assessing infection risk. We further evaluated this association in an orthopedic specialty hospital arthroplasty cohort to evaluate whether BSA is a predictor of prosthetic joint infection.

Methods

A retrospective cohort of hip and knee arthroplasty patients between 2009 and 2014 was identified through administrative hospital data using ICD-9 codes. Patients with a BMI &lt;14 or &gt;60 kg/m2, height &lt;142 or &gt;200 cm, and weight &lt;36 or &gt;226 kg were excluded. BSA was calculated using the DuBois formula, and assessed both as a continuous and as a categorical variable. Univariate analyses were done using χ 2 tests and adjusted models were assessed using logistic regression.

Results

17,859 knee and 18,128 hip patients were identified. 1.1% of knees and 0.74% of hips were infected.]Mean BSA was 1.9 m2 (±0.2 m2). BSA was significantly associated with PJI in hips (P = 0.004), but not knees, when analyzed as a continuous variable in unadjusted models. However, this association lost its significance after adjusting for PJI risk factors. Additionally, when assessed as a categorical variable in a multivariate model, BSA in the highest quartile (&gt;2.11) was not associated with PJI.

Conclusion

After evaluating BSA as a continuous and categorical variable, we failed to find an association between BSA and infection risk in THA or TKA. The impact of BSA decreased after multivariate adjustment. BSA may not be optimal as a predictor of preoperative risk.

Disclosures

All authors: No reported disclosures.

2017 American College of Rheumatology/American Association of Hip and Knee Surgeons Guideline for the Perioperative Management of Antirheumatic Medication in Patients With Rheumatic Diseases Undergoing Elective Total Hip or Total Knee Arthroplasty

OBJECTIVE

This collaboration between the American College of Rheumatology and the American Association of Hip and Knee Surgeons developed an evidence-based guideline for the perioperative management of antirheumatic drug therapy for adults with rheumatoid arthritis (RA), spondyloarthritis (SpA) including ankylosing spondylitis and psoriatic arthritis, juvenile idiopathic arthritis (JIA), or systemic lupus erythematosus (SLE) undergoing elective total hip (THA) or total knee arthroplasty (TKA).

METHODS

A panel of rheumatologists, orthopedic surgeons specializing in hip and knee arthroplasty, and methodologists was convened to construct the key clinical questions to be answered in the guideline. A multi-step systematic literature review was then conducted, from which evidence was synthesized for continuing versus withholding antirheumatic drug therapy and for optimal glucocorticoid management in the perioperative period. A Patient Panel was convened to determine patient values and preferences, and the Grading of Recommendations Assessment, Development and Evaluation methodology was used to rate the quality of evidence and the strength of recommendations, using a group consensus process through a convened Voting Panel of rheumatologists and orthopedic surgeons. The strength of the recommendation reflects the degree of certainty that benefits outweigh harms of the intervention, or vice versa, considering the quality of available evidence and the variability in patient values and preferences.

RESULTS

The guideline addresses the perioperative use of antirheumatic drug therapy including traditional disease-modifying antirheumatic drugs, biologic agents, tofacitinib, and glucocorticoids in adults with RA, SpA, JIA, or SLE who are undergoing elective THA or TKA. It provides recommendations regarding when to continue, when to withhold, and when to restart these medications, and the optimal perioperative dosing of glucocorticoids. The guideline includes 7 recommendations, all of which are conditional and based on low- or moderate-quality evidence.

CONCLUSION

This guideline should help decision-making by clinicians and patients regarding perioperative antirheumatic medication management at the time of elective THA or TKA. These conditional recommendations reflect the paucity of high-quality direct randomized controlled trial data.

2017 American College of Rheumatology/American Association of Hip and Knee Surgeons Guideline for the Perioperative Management of Antirheumatic Medication in Patients With Rheumatic Diseases Undergoing Elective Total Hip or Total Knee Arthroplasty

OBJECTIVE

This collaboration between the American College of Rheumatology and the American Association of Hip and Knee Surgeons developed an evidence-based guideline for the perioperative management of antirheumatic drug therapy for adults with rheumatoid arthritis (RA), spondyloarthritis (SpA) including ankylosing spondylitis and psoriatic arthritis, juvenile idiopathic arthritis (JIA), or systemic lupus erythematosus (SLE) undergoing elective total hip (THA) or total knee arthroplasty (TKA).

METHODS

A panel of rheumatologists, orthopedic surgeons specializing in hip and knee arthroplasty, and methodologists was convened to construct the key clinical questions to be answered in the guideline. A multi-step systematic literature review was then conducted, from which evidence was synthesized for continuing versus withholding antirheumatic drug therapy and for optimal glucocorticoid management in the perioperative period. A Patient Panel was convened to determine patient values and preferences, and the Grading of Recommendations Assessment, Development and Evaluation methodology was used to rate the quality of evidence and the strength of recommendations, using a group consensus process through a convened Voting Panel of rheumatologists and orthopedic surgeons. The strength of the recommendation reflects the degree of certainty that benefits outweigh harms of the intervention, or vice versa, considering the quality of available evidence and the variability in patient values and preferences.

RESULTS

The guideline addresses the perioperative use of antirheumatic drug therapy including traditional disease-modifying antirheumatic drugs, biologic agents, tofacitinib, and glucocorticoids in adults with RA, SpA, JIA, or SLE who are undergoing elective THA or TKA. It provides recommendations regarding when to continue, when to withhold, and when to restart these medications, and the optimal perioperative dosing of glucocorticoids. The guideline includes 7 recommendations, all of which are conditional and based on low- or moderate-quality evidence.

CONCLUSION

This guideline should help decision-making by clinicians and patients regarding perioperative antirheumatic medication management at the time of elective THA or TKA. These conditional recommendations reflect the paucity of high-quality direct randomized controlled trial data.

Candida osteomyelitis: analysis of 207 pediatric and adult cases (1970-2011)

BACKGROUND

The epidemiology, pathogenesis, clinical manifestations, management, and outcome of Candida osteomyelitis are not well understood.

METHODS

Cases of Candida osteomyelitis from 1970 through 2011 were reviewed. Underlying conditions, microbiology, mechanisms of infection, clinical manifestations, antifungal therapy, and outcome were studied in 207 evaluable cases.

RESULTS

Median age was 30 years (range, ≤ 1 month to 88 years) with a >2:1 male:female ratio. Most patients (90%) were not neutropenic. Localizing pain, tenderness, and/or edema were present in 90% of patients. Mechanisms of bone infection followed a pattern of hematogenous dissemination (67%), direct inoculation (25%), and contiguous infection (9%). Coinciding with hematogenous infection, most patients had ≥2 infected bones. When analyzed by age, the most common distribution of infected sites for adults was vertebra (odds ratio [OR], 0.09; 95% confidence interval [CI], .04-.25), rib, and sternum; for pediatric patients (≤18 years) the pattern was femur (OR, 20.6; 95% CI, 8.4-48.1), humerus, then vertebra/ribs. Non-albicans Candida species caused 35% of cases. Bacteria were recovered concomitantly from 12% of cases, underscoring the need for biopsy and/or culture. Candida septic arthritis occurred concomitantly in 21%. Combined surgery and antifungal therapy were used in 48% of cases. The overall complete response rate of Candida osteomyelitis of 32% reflects the difficulty in treating this infection. Relapsed infection, possibly related to inadequate duration of therapy, occurred among 32% who ultimately achieved complete response.

CONCLUSIONS

Candida osteomyelitis is being reported with increasing frequency. Localizing symptoms are usually present. Vertebrae are the most common sites in adults vs femora in children. Timely diagnosis of Candida osteomyelitis with extended courses of 6-12 months of antifungal therapy, and surgical intervention, when indicated, may improve outcome.

Custom total femur spacer and second-stage total femur arthroplasty as a novel approach to infection and periprosthetic fracture

Total femur arthroplasty procedures have previously been used after tumor excision and as a last resort for failed revision arthroplasty. The patient in this case presented with massive loss of femoral bone stock, a periprosthetic fracture, and recurrent Staphylococcus epidermidis infection. A specially designed total femoral spacer impregnated with antibiotics was created for a 2-stage revision procedure that successfully restored functional ability and eradicated the infection. Although 2-stage protocols with spacers have been used to treat persistent infections after hip and knee arthroplasty, this is the first reported instance of the creation of a total femur antibiotic-impregnated cement spacer and subsequent total femoral arthroplasty as a 2-stage protocol at our institution.

Liquid gentamicin in bone cement: a laboratory study of a potentially more cost-effective cement spacer

BACKGROUND

Liquid gentamicin is approved by the Food and Drug Administration, is readily available, and is much less costly than tobramycin, the more commonly used antibiotic in cement spacers. The purpose of the present study was to test the mechanical properties, elution characteristics, and antibacterial activity of liquid gentamicin in an acrylic bone cement spacer.

METHODS

Standardized specimens consisting of Palacos cement combined with liquid gentamicin, powdered tobramycin, or no antibiotic were fashioned, and the three groups were tested with regard to compressive and tensile strength, elution characteristics (with use of radioimmunoassays), and antibacterial activity (with use of bioassays).

RESULTS

The ultimate compression strength decreased by 49% (from 64.65 +/- 3.89 MPa to 32.96 +/- 3.33 MPa) and the ultimate tension strength decreased by 46% (from 35.85 +/- 2.97 MPa to 19.20 +/- 0.36 MPa) when the specimens containing 480 mg of liquid gentamicin were compared with the controls. The addition of tobramycin had no significant effect compared with the controls. The majority of gentamicin was released from the cement during the initial twenty-four hours (mean concentration, 26.4 mcg/mL). The mean concentrations at three and six weeks were 4.15 and 0.65 mcg/mL, respectively. The bioassays confirmed the bactericidal activity of the gentamicin released from the cement.

CONCLUSIONS

Liquid gentamicin in bone cement is potent and bactericidal. Although the mechanical properties of the cement are significantly diminished by the addition of liquid gentamicin, the temporary nature of the cement spacer makes its use potentially worthwhile given the substantial cost savings to the hospital and the patient.

Effective bactericidal activity of tobramycin and vancomycin eluted from acrylic bone cement

We studied the bioactivity of vancomycin and tobramycin eluted from methylmethacrylate bone cement. Aliquots of the drainage were obtained at 1, 6, 12 and 24 hours following total hip prosthetic implantation with vancomycin-tobramycin-loaded cement in 3 patients. The samples were analyzed with fluorescence polarization immunoassay and bioassay, using group B streptococcus for vancomycin and Escherichia coli for tobramycin. These bacteria were selected due to the effectiveness of vancomycin and poor effectiveness of tobramycin against group B streptococcus and conversely with E. coli. The immunodetection of vancomycin averaged 14 (1 hour), 9 (6 hours), 10 (12 hours) and 11 microg/mL (24 hours). The bioassay averaged 47, 36, 79 and 41 microg/mL (p = 0.03). The immunodetection of tobramycin averaged 43, 21, 18 and 14 microg/mL; and bioassay 30, 15, 15 and 12 microg/mL (p = 0.1). Both antibiotics eluted with a highly effective bactericidal activity. Our findings indicate that the presence of tobramycin has a synergistic-like effect on the bactericidal activity of vancomycin, which has not been previously reported. We recommend a combination of vancomycin and tobramycin with cement for the treatment of orthopedic infections caused by gram-positive organisms.

Antibiotic impregnated bone cement in total hip arthroplasty. An in vivo comparison of the elution properties of tobramycin and vancomycin

A prospective in vivo quantification was performed to measure the elution of tobramycin and vancomycin antibiotics from two commonly used bone cements. Forty patients were divided into four groups: Group I, tobramycin-Simplex; Group II, tobramycin-Palacos-R; Group III, vancomycin-Simplex; and Group IV, vancomycin-Palacos-R. Antibiotic levels were measured from hemovac wound drainage, urine, and serum and compared with control groups who received either intravenous tobramycin or vancomycin. There were no significant differences in daily mean tobramycin levels in hemovac samples between Groups I and II. Tobramycin hemovac levels from Groups I and II were significantly higher than the tobramycin control group. Similarly, no differences were seen in daily mean vancomycin levels of the hemovac samples between Group III and IV; however, the intravenous vancomycin control group had significantly higher levels in the hemovac fluid than Groups III or IV. Tobramycin in the hemovac fluid from Groups I and II was highly bioactive against the control organism. Vancomycin in the hemovac fluid from Groups III and IV had variable bioactivity against the control organism. In 30% of the cases, no vancomycin was detected in the hemovac fluid, and in these cases, the hemovac fluid had no effect on the control organism. Tobramycin elutes to give adequate local tissue levels and releases antibiotic effects when used in an antibiotic bone cement combination. Vancomycin has variable elution properties and is not a predictable additive for the bone cements tested.