Factors Associated With an Intra-articular Infection After Anterior Cruciate Ligament Reconstruction: A Large Single-Institution Cohort Study

BACKGROUND

An intra-articular infection after anterior cruciate ligament (ACL) reconstruction (ACLR) is a rare complication but one with potentially devastating consequences. The rare nature of this complication raises difficulties in detecting risk factors associated with it and with worse outcomes after one has occurred.

PURPOSE

To (1) evaluate the association between an infection after ACLR and potential risk factors in a large single-center cohort of patients who had undergone ACLR and (2) assess the factors associated with ACL graft retention versus removal.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

All ACLR procedures performed at our institution between January 2010 and December 2018 were reviewed; a total of 11,451 procedures were identified. A retrospective medical record review was performed to determine the incidence of infections, patient and procedure characteristics associated with an infection, infection characteristics, incidence of ACL graft retention, and factors associated with the retention versus removal of an ACL graft. Multivariable logistic regression analysis was used to identify potential risk factors for an infection after ACLR.

RESULTS

Of the 11,451 ACLR procedures, 48 infections were identified (0.42%). Multivariable logistic regression analysis revealed revision ACLR (odds ratio [OR], 3.13 [95% CI, 1.55-6.32]; P = .001) and younger age (OR, 1.06 [95% CI, 1.02-1.10]; P = .001) as risk factors for an infection. Compared with bone-patellar tendon-bone autografts, both hamstring tendon autografts (OR, 4.39 [95% CI, 2.15-8.96]; P < .001) and allografts (OR, 5.27 [95% CI, 1.81-15.35]; P = .002) were independently associated with an increased risk of infections. Overall, 15 ACL grafts were removed (31.3%). No statistically significant differences besides the number of irrigation and debridement procedures were found for retained versus removed grafts, although some trends were identified (P = .054).

CONCLUSION

In a large single-center cohort of patients who had undergone ACLR and those with an infection after ACLR, patients with revision cases and younger patients were found to have a higher incidence of infection. The use of bone-patellar tendon-bone autografts was found to be associated with the lowest risk of infection after ACLR compared with both hamstring tendon autografts and allografts. Larger cohorts with a larger number of infection cases are needed to determine the factors associated with graft retention versus removal.

Sequencing of Circulating Microbial Cell-Free DNA Can Identify Pathogens in Periprosthetic Joint Infections

BACKGROUND

Over 1 million Americans undergo joint replacement each year, and approximately 1 in 75 will incur a periprosthetic joint infection. Effective treatment necessitates pathogen identification, yet standard-of-care cultures fail to detect organisms in 10% to 20% of cases and require invasive sampling. We hypothesized that cell-free DNA (cfDNA) fragments from microorganisms in a periprosthetic joint infection can be found in the bloodstream and utilized to accurately identify pathogens via next-generation sequencing.

METHODS

In this prospective observational study performed at a musculoskeletal specialty hospital in the U.S., we enrolled 53 adults with validated hip or knee periprosthetic joint infections. Participants had peripheral blood drawn immediately prior to surgical treatment. Microbial cfDNA from plasma was sequenced and aligned to a genome database with >1,000 microbial species. Intraoperative tissue and synovial fluid cultures were performed per the standard of care. The primary outcome was accuracy in organism identification with use of blood cfDNA sequencing, as measured by agreement with tissue-culture results.

RESULTS

Intraoperative and preoperative joint cultures identified an organism in 46 (87%) of 53 patients. Microbial cfDNA sequencing identified the joint pathogen in 35 cases, including 4 of 7 culture-negative cases (57%). Thus, as an adjunct to cultures, cfDNA sequencing increased pathogen detection from 87% to 94%. The median time to species identification for cases with genus-only culture results was 3 days less than standard-of-care methods. Circulating cfDNA sequencing in 14 cases detected additional microorganisms not grown in cultures. At postoperative encounters, cfDNA sequencing demonstrated no detection or reduced levels of the infectious pathogen.

CONCLUSIONS

Microbial cfDNA from pathogens causing local periprosthetic joint infections can be detected in peripheral blood. These circulating biomarkers can be sequenced from noninvasive venipuncture, providing a novel source for joint pathogen identification. Further development as an adjunct to tissue cultures holds promise to increase the number of cases with accurate pathogen identification and improve time-to-speciation. This test may also offer a novel method to monitor infection clearance during the treatment period.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Bacterial toxins in musculoskeletal infections

Musculoskeletal infections (MSKIs) remain a major health burden in orthopaedics. Bacterial toxins are foundational to pathogenesis in MSKI, but poorly understood by the community of providers that care for patients with MSKI, inducing an international group of microbiologists, infectious diseases specialists, orthopaedic surgeons and biofilm scientists to review the literature in this field to identify key topics and compile the current knowledge on the role of toxins in MSKI, with the goal of illuminating potential impact on biofilm formation and dispersal as well as therapeutic strategies. The group concluded that further research is needed to maximize our understanding of the effect of toxins on MSKIs, including: (i) further research to identify the roles of bacterial toxins in MSKIs, (ii) establish the understanding of the importance of environmental and host factors and in vivo expression of toxins throughout the course of an infection, (iii) establish the principles of drug-ability of antitoxins as antimicrobial agents in MSKIs, (iv) have well-defined metrics of success for antitoxins as antiinfective drugs, (v) design a cocktail of antitoxins against specific pathogens to (a) inhibit biofilm formation and (b) inhibit toxin release. The applicability of antitoxins as potential antimicrobials in the era of rising antibiotic resistance could meet the needs of day-to-day clinicians.

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

Background: The role of daptomycin, a potent, safe, convenient anti-staphylococcal antibiotic, in treatment of prosthetic joint infection (PJI) is unclear. We evaluated our experience with the largest cohort of patients with staphylococcal PJI managed with daptomycin. Methods: A cohort of staphylococcal hip and knee PJI treated with daptomycin was identified by hospital records from 2009 to 2016. All cases met Musculoskeletal Infection Society International Consensus criteria for PJI. The primary endpoint was 2 year prosthesis retention. Univariate analyses and regression statistics were calculated. Results: 341 patients with staphylococcal PJI were analyzed. 154 two-stages (77%) and 74 DAIR procedures (52%) met criteria for treatment success at 2 years. 77 patients were treated with daptomycin, of which 34 two-stages (68%) and 15 DAIRs (56%) achieved treatment success. Pairwise and regression analysis found no association between treatment success and daptomycin use. Organism (DAIR only) and Charlson Comorbidity Index scores (DAIR and two-stage) were significantly associated with treatment outcome. Six daptomycin patients (7.8%) had adverse side effects. Discussion: Daptomycin fared no better or worse than comparable antibiotics in a retrospective cohort of staphylococcal hip and knee PJI patients, regardless of surgical strategy. Conclusion: The convenient dosing, safety, and potency of daptomycin make it an attractive antibiotic for staphylococcal PJI. However, these advantages must be weighed against higher costs and rare, but serious side effects.

Musculoskeletal Infection Society (MSIS) Update on Infection in Arthroplasty

Periprosthetic joint infection (PJI) continues to be a devastating problem in the field of total joint arthroplasty, and recent literature can be used to make the preoperative diagnosis of PJI, guide nonsurgical and surgical treatment, and provide postoperative antimicrobial management of PJI patients. The diagnosis of PJI relies on traditional serum and synovial fluid tests, with newer biomarkers and molecular tests. Surgical treatment depends on the duration of infection, host qualities, and surgeon factors, and procedures include débridement, antibiotics, and implant retention, one-stage exchange arthroplasty, two-stage exchange arthroplasty, resection arthroplasty, fusion, or amputation. Appropriate management of PJI involves coordination with infectious disease consultants, internal medicine physicians, and orthopaedic surgeons. Antimicrobial management is guided by the organisms involved, whether it is a new or persistent infection, and antibiotic suppression should be administered on an individual case basis. The goals of this instructional course lecture are to review the most relevant recent literature and provide treating physicians and surgeons with the most up-to-date armamentarium to reduce the recurrence of PJI.

Fungal Musculoskeletal Infections

Fungi are rare but important causes of osteoarticular infections, and can be caused by a wide array of yeasts and molds. Symptoms are often subacute and mimic those of other more common causes of osteoarticular infection, which can lead to substantial delays in treatment. A high index of suspicion is required to establish the diagnosis. The severity of infection depends on the inherent pathogenicity of the fungi, the immune status of the host, the anatomic location of the infection, and whether the infection involves a foreign body. Treatment often involves a combination of surgical debridement and prolonged antifungal therapy.

Globicatella sanguinis Osteomyelitis and Bacteremia: Review of an Emerging Human Pathogen with an Expanding Spectrum of Disease

Background

Globicatella sanguinis is an uncommon pathogen that may be misdiagnosed as viridans group streptococci. We review the literature of Globicatella and report 2 clinical cases in which catalase-negative Gram-positive cocci resembling viridans group streptococci with elevated minimum inhibitory concentrations (MICs) to ceftriaxone were inconsistently identified phenotypically, with further molecular characterization and ultimate identification of G sanguinis.

Methods

Two clinical strains (from 2 obese women; 1 with a prosthetic hip infection and the other with bacteremia) were analyzed with standard identification methods, followed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, 16S recombinant ribonucleic acid (rRNA), and sodA polymerase chain reaction (PCR). The existing medical literature on Globicatella also was reviewed.

Results

Standard phenotypic methods failed to consistently identify the isolates. 16S PCR yielded sequences that confirmed Globicatella species. sodA sequencing provided species-level identification of G sanguinis. The review of literature reveals G sanguinis as an increasingly reported cause of infections of the urine, meninges, and blood. To our knowledge, this is the first reported case of an orthopedic infection caused by Globicatella sanguinis. A review of the 37 known cases of G sanguinis infection revealed that 83% of patients are female, and 89% are at the extremes of age (<5 or >65 years).

Conclusions

Globicatella sanguinis, an uncommon pathogen with elevated minimum inhibitory concentrations to third-generation cephalosporins, is difficult to identify by phenotypic methods and typically causes infections in females at the extremes of age. It may colonize skin or mucosal surfaces. Advanced molecular techniques utilizing 16S rRNA with sodA PCR accurately identify G sanguinis.

Prosthetic joint infections secondary to rapidly growing mycobacteria: Two case reports and a review of the literature

Rapidly growing mycobacteria (RGM) are a rare but treatable cause of prosthetic joint infections. This study reports on two patients comprising three prosthetic joint infections caused by RGM successfully treated at the institution. With removal of the infected prosthetic joint and judicious use of prolonged courses of antibiotics, patients with prosthetic joint infections secondary to RGM can both be cured and retain function of the affected joint. In addition, this study identified 40 additional cases reported during an extensive review of the literature and provide a summary of these cases. These infections can present within days of arthroplasty or can develop only decades after the index surgery. The clinical presentations often mimic those of more routine bacterial prosthetic joint infections.

Successful treatment of Candida osteoarticular infections with limited duration of antifungal therapy and orthopedic surgical intervention

BACKGROUND

Current guidelines for treatment of Candida osteoarticular infections (COAIs) recommend a prolonged course of antifungal therapy (AFT) of 6-12 months. Based upon strategies developed at the Hospital for Special Surgery (HSS), we hypothesized that the duration of antifungal therapy may be substantially reduced for management of COAI.

METHODS

This was a retrospective chart review of cases of COAI treated at the HSS for the past 14 years. COAI was documented by open biopsy and direct culture in all cases. The mean (95% confidence interval, CI) duration of documented follow-up was 39 (16-61) months.

RESULTS

Among the 23 cases of COAI, the median age was 62 years (range 22-83 years) with 61% having no underlying condition. Orthopedic appliances, including joint prostheses and fracture hardware, were present in 74% of cases. All patients had COAI as the first proven site of candidiasis. Candida albicans and Candida parapsilosis were the most common species. Hip, knee, foot, and ankle were the most common sites. All patients received aggressive surgical intervention followed by AFT administered for a mean (95% CI) duration of 45 (38-83) days. Systemic AFT consisted principally of fluconazole alone (65%) or in combination with other agents (26%). Adjunctive intraoperative amphotericin B irrigation was used in 35%. Among eight cases of CAOI that required placement of a new prosthetic joint, all were successfully treated. There were no microbiologic failures.

CONCLUSIONS

Candida osteoarticular infections may be successfully treated with substantially limited durations of AFT when combined with a thorough surgical approach.

Postoperative infections of the lumbar spine: presentation and management

PURPOSE

Postoperative surgical site infections (SSI) are a frequent complication following posterior lumbar spinal surgery. In this manuscript we review strategies for prevention, diagnosis and treatment of SSI.

METHODS

The literature was reviewed using the Pubmed database.

RESULTS

We identified fifty-nine relevant manuscripts almost exclusively composed of Level III and IV studies.

CONCLUSIONS

Risk factors for SSI include: 1) factors related to the nature of the spinal pathology and the surgical procedure and 2) factors related to the systemic health of the patient. Staphylococcus aureus is the most common infectious organism in reported series. Proven methods to prevent SSI include prophylactic antibiotics, meticulous adherence to aseptic technique and frequent release of retractors to prevent myonecrosis. The presentation of SSI is varied depending on the virulence of the infectious organism. Frequently, increasing pain is the only presenting complaint and can lead to a delay in diagnosis. Magnetic resonance imaging and the use of C-reactive protein laboratory studies are useful to establish the diagnosis. Treatment of SSI is centered on surgical debridement of all necrotic tissue and obtaining intra-operative cultures to guide antibiotic therapy. We recommend the involvement of an infectious disease specialist and use of minimum serial bactericidal titers to monitor the efficacy of antibiotic treatment. In the most cases, SSI can be adequately treated while leaving spinal instrumentation in place. For severe SSI, repeat debridement, delayed closure and involvement of a plastic surgeon may be necessary.

Historical perspective on two-stage reimplantation for infection after total hip arthroplasty at Hospital for Special Surgery, New York City

In this article, we report on our use of a 2-stage exchange in managing infected total hip arthroplasties (THAs) at the Hospital for Special Surgery in New York City. This protocol involves resection arthroplasty, 6 weeks of intravenous antibiotics to obtain a minimum "postpeak" serum bactericidal titer (SBT) of 1:8, and reimplantation. Over the past 20 years, we have conducted several studies showing the effectiveness of this treatment. Since our previous report was published in 1994, prevalence of multidrug-resistant (MDR) organisms has increased significantly. In 2008, we set out to determine if 2-stage exchange remains an effective treatment for newer pathogens, many of which are MDR. The overall eradication rate was 95% (80/84 hips). All 21 MDR pathogens implicated in the infected THAs were eradicated. We conclude that 2-stage exchange with a standard 1:8 minimum SBT remains an effective treatment even when resistant infections are involved.

Modern treatment of infected total knee arthroplasty with a 2-stage reimplantation protocol

The purpose of this study was to determine if 2-stage reimplantation for the treatment of infected total knee arthroplasty (TKA) is still effective for treating contemporary pathogens, many of which are multidrug resistant (MDR). The medical records of all cases of infected TKAs from April 1998 to March 2006 were retrospectively reviewed for data on infecting organism and success of treatment. Of 72 patients (75 knees), with a minimum of 2 years of follow-up, who completed the protocol, the infection was eradicated in 90.7% (68/75 knees). Thirty-one (91.2%) of 34 of MDR infections and 42 (91.3%) of 46 of non-MDR infections were successfully treated. These results support previous studies that demonstrated the effectiveness of a 2-stage reimplantation protocol with a standard 1:8 minimal bactericidal titer for treating infections after TKA, including MDR organisms.

Propionibacterium acnes infection after shoulder arthroplasty: a diagnostic challenge

HYPOTHESIS

This study reviewed a series of patients diagnosed with Propionibacterium acnes infection after shoulder arthroplasty in order to describe its clinical presentation, the means of diagnosis, and provide options for treatment.

MATERIALS AND METHODS

From 2002 to 2006, 11 patients diagnosed with P acnes infection after shoulder arthroplasty were retrospectively reviewed and analyzed for (1) clinical diagnosis; (2) laboratory data, including white blood cell count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP); (3) fever; (4) number of days for laboratory growth of P acnes; (5) organism sensitivities; (6) antibiotic regimen and length of treatment; and (7) surgical management. Infection was diagnosed by 2 positive cultures.

RESULTS

Five patients had an initial diagnosis of infection and underwent implant removal, placement of an antibiotic spacer, and staged reimplantation after a course of intravenous antibiotics. In the remaining 6 patients, surgical treatment varied according to the clinical diagnosis. When infection was recognized by intraoperative cultures, antibiotics were initiated. The average initial ESR and CRP values were 33 mm/h and 2 mg/dL, respectively. The average number of days from collection to a positive culture was 9. All cultures were sensitive to penicillin and clindamycin and universally resistant to metronidazole.

DISCUSSION

Prosthetic joint infection secondary to P acnes is relatively rare; yet, when present, is an important cause of clinical implant failure. Successful treatment is hampered because clinical findings may be subtle, many of the traditional signs of infection are not present, and cultures may not be positive for as long as 2 weeks.

Dental premedication protocols for patients with knee and hip protheses

In 1997, the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS) published an advisory statement regarding antibiotic prophylaxis for patients with total joint replacements undergoing dental treatment. The first periodic update of these guidelines was published in 2003. Nevertheless, confusion exists among dentists and physicians as to the clinical indications for premedication in this patient population. This article serves as an overview of current recommendations for use of chemoprophylaxis in the dental treatment of patients ith prosthetic joints.

Flexor tenosynovitis caused by Mycobacterium scrofulaceum: case report

Atypical hand infections with Mycobacterium species are uncommon, and Mycobacterium scrofulaceum infections are rare. We present a case of flexor tenosynovitis caused by M scrofulaceum in a 66-year-old man with hypertension and diabetes.

Dental premedication protocols for patients with knee and hip prostheses

In 1997, the American Dental Association (ADA) and the American Academy of Orthopaedic Surgeons (AAOS) published an advisory statement regarding antibiotic prophylaxis for patients with total joint replacements undergoing dental treatment. The first periodic update of these guidelines was published in 2003. Nevertheless, confusion exists among dentists and physicians as to the clinical indications for premedication in this patient population. This article serves as an overview of current recommendations for use of chemoprophylaxis in the dental treatment of patients with prosthetic joints.

Candida infection after total knee arthroplasty. Management without resection or amphotericin B

A rare case of Candida infection after revision total knee arthroplasty that was treated medically, without amphotericin B or resection arthroplasty, is reported. This case occurred in an elderly patient without predisposing medical problems. The patient was treated with only a suppressive dose of ketoconazole. The patient was last evaluated 6 years after the revision surgery and had no problem or signs of infection. Factors contributing to successful medical treatment in this case were likely the routine debridement at revision surgery and the patient's intact immune system.

Septic arthritis after arthroscopic anterior cruciate ligament reconstruction. Diagnosis and management

We performed a retrospective study of knee joint infections after arthroscopic anterior cruciate ligament reconstruction at our institution. Two thousand five hundred anterior cruciate ligament reconstructions were performed between 1988 and 1993. Seven (0.3%) patients experienced postoperative deep infections of the knee. All anterior cruciate ligament reconstructions were performed using arthroscopically assisted techniques. Six (86%) of these patients had concomitant open procedures performed, including meniscal repair, posterolateral corner reconstruction, and medial collateral ligament reconstruction. Four patients had acute (< 2 weeks), two patients had subacute (2 weeks to 2 months), and one patient had late (> 2 months) infections. All patients had positive cultures from knee joint aspirates with the organisms Staphylococcus aureus, Staphylococcus epidermidis, Peptostreptococcus, or a combination thereof. All patients underwent immediate arthroscopic irrigation and debridement. All infections were intraarticular; six patients also had extraarticular sites of infection. Four patients underwent repeat irrigation and debridement at approximately 1 week. The anterior cruciate ligament graft was removed from four patients. All patients were treated with intravenous antibiotics for 4 to 6 weeks, protected weightbearing, and physical therapy. At a mean followup of 29 months, mean knee extension was 0 degree, and mean knee flexion was 122 degrees (range, 70 degrees to 135 degrees). Six (86%) patients had minimal to no pain in their operative knee, and they were satisfied with their functional results.

Multiple prosthetic infections after total joint arthroplasty. Risk factor analysis

The relative risk of age, sex, underlying diagnosis, corticosteroid usage, diabetes mellitus, and major nonprosthetic infection for the development of multiple prosthetic infections was assessed retrospectively. Deep infection occurred in 174 replacement arthroplasties in 145 patients between 1981 and 1993. Patients with rheumatoid arthritis had a significantly larger number of implants per patient (P < .001). Twenty-seven of 145 patients developed a second prosthetic infection, for an overall incidence of 19%. Of these 27, the underlying diagnoses were rheumatoid arthritis in 19, osteoarthritis in 6, neuropathic arthritis in 1, and systemic lupus erythematosus in 1. Rheumatoid arthritis and the occurrence of a major nonprosthetic infection (sepsis) were found to be highly associated with the development of a second prosthetic infection (P < .001 and P = .0001, respectively). In those rheumatoid patients with multiple infections, there was a significantly larger proportion with American Rheumatism Association class III and IV function than those with a single prosthetic infection (P = .0002). In 14 of the 27 cases of more than one prosthetic infection, the infected implants presented clinically within the same month. Ten of these 14 had an associated nonprosthetic infection. It is therefore not possible to accurately calculate the risk that one infected arthroplasty poses to other implants.

Treatment of the infected total hip arthroplasty with a two-stage reimplantation protocol

Forty-four patients (46 hips) with infected total hip arthroplasties were evaluated. They were entered into a protocol that included resection arthroplasty, six weeks of intravenous antibiotics which obtained a minimum postpeak serum bactericidal titer of 1:8, and possible reimplantation. Thirty-two of 46 hips (70%) were reimplanted. At an average of 40 months (range, 24-74 months) after reimplantation, infection recurred in three hips (9%). In two of the three recurrent infections, 1:8 bactericidal titers were not attained. Both of these hips were infected with gram-negative organisms. Minimum postpeak serum bactericidal titers of 1:8 were attained in 28 of 32 hips that were reimplanted, and only one of these hips (4%) had a recurrent infection (p = 0.035). The presence of retained cement after resection arthroplasty (ten hips) was not associated with recurrent infection. Fourteen hips (12 patients were not reimplanted as a result of a combination of factors, including inadequate bone stock, poor soft-tissue quality, and antibiotic resistance of the infecting organism. The treatment of an infected total hip arthroplasty with resection arthroplasty, six weeks of intravenous antibiotics that attains a minimum postpeak serum bactericidal titer of 1:8, and reimplantation can be an effective and safe treatment.

Palacos gentamicin for the treatment of deep periprosthetic hip infections

Between 1983 and 1986, 40 hip arthroplasties in 40 patients with documented deep infection were reimplanted using Palacos Gentamicin at The Hospital for Special Surgery. Palacos Gentamicin was added to the standard protocol, which included removal of the prosthesis, cement, if present, and a thorough debridement of infected and necrotic tissue, six weeks of intravenous antibiotics with a postpeak serum bactericidal titer of at least 1:8 against the infecting bacteria, followed by reimplantation of the hip. Sixteen of the patients also had the placement of gentamicin-impregnated beads at the time of prosthetic removal. All patients had a deep periprosthetic infection, 13 with Staphylococcus epidermidis, seven Staphylococcus aureus, four Streptococcus, three Enterococcus, three with gram-positive bacteria, four Escherichia coli, two Proteus, one Pseudomonas, and three anaerobic organisms. At an average follow-up period of five years (range, two to ten), two of the 40 hips (5%) developed recurrent infection. These cases recurred at one month in a patient immunocompromised by end-stage systemic lupus erythematosus (S. epidermidis) and at five months in a patient with severe titanium metallosis (S. aureus). No recurrence was noted in eight cases with gram-negative organisms or in three cases of mixed infections. No infection recurred after five months in the remaining patients before their death or last follow-up examination. Of the remaining 38 hips, 16 died of causes unrelated to the hip, leaving 21 with an average follow-up period of 7.5 years. Clinical results in these patients were 14 excellent, five good, two fair, and no poor results.(ABSTRACT TRUNCATED AT 250 WORDS)

Treatment of experimental osteomyelitis with antibiotic-impregnated bone graft substitute

The model of Norden was used to induce osteomyelitis in the left tibia of New Zealand White rabbits. Twenty-one days following inoculation, the animals had primary debridement and then were randomized into one of three treatment groups. Group I received no additional treatment; in Group II, plain hydroxyapatite beads were packed into the defect; and in Group III, gentamicin crobefat-loaded hydroxyapatite beads were packed into the defect. The animals were observed for 40 days after the primary debridement and then were killed. The intensity of infection was determined by swab cultures and quantitative bacterial cultures of the debrided material. At primary debridement, all of the animals in each group were equally infected. At the time of secondary debridement, only the animals in Group III had a statistically significant reduction in infection (p < 0.001). In this study, we demonstrated that an antibiotic-loaded osteoinductive ceramic bead can effectively eliminate bacteria from an osteomyelitic cavity.

Gastrocnemius muscle flap coverage of exposed or infected knee prostheses

A retrospective analysis was performed of 12 patients who required soft-tissue coverage of an exposed or infected total knee prosthesis between 1982 and 1989. All knees had skin closure with medial gastrocnemius muscle flaps. At a mean follow-up period of 41 months, all patients who were treated for infected prostheses with removal of the implant, intravenous antibiotics, and muscle flap closure had an excellent clinical result with complete skin coverage and no infection. Five of the six patients went on to successful reimplantation. Of the patients with an exposed prosthesis, five of six had an excellent outcome with retention of the prosthesis. Thus, 11 of 12 patients (92%) who had medial gastrocnemius flap coverage of an exposed or infected knee prosthesis had an excellent outcome, with ten of 12 patients (82%) retaining their prostheses or having a successful reimplantation. No medial gastrocnemius flap failed after standard primary or revision total knee arthroplasty. Gastrocnemius muscle flaps provide excellent soft-tissue coverage of exposed or infected knee prostheses and facilitate surgical care of this difficult problem.

Two-stage reimplantation for the salvage of total knee arthroplasty complicated by infection. Further follow-up and refinement of indications

Thirty-eight total knee replacements (in thirty-five patients) that were complicated by infection were treated with a two-stage protocol for reimplantation. The clinical results in these knees (nine of which have been previously reported on) were evaluated at an average follow-up of four years (range, 2.5 to ten years). There was only one documented recurrence of infection with the original organism. Three patients in whom the immunological system was suppressed had a subsequent hematogenous infection with a different organism. According to the knee-rating system of The Hospital for Special Surgery, there were eleven excellent, thirteen good, six fair, and seven poor results. For one patient who had severe polyarticular rheumatoid arthritis, the result could not be rated. The results of this study suggested that the two-stage protocol for reimplantation, with a six-week interval of intravenous antibiotic therapy, is the procedure of choice for the treatment of an infection around a total knee arthroplasty. A patient who has polyarticular rheumatoid arthritis and in whom the immunological system is suppressed may not be an ideal candidate for the protocol. Gram-negative bacterial infection may be treated with this protocol, provided the organism is sensitive to relatively non-toxic antibiotic medication.

Role of gentamicin-impregnated cement in total joint arthroplasty

Palacos-Gentamicin (PG) was used in 130 joint arthroplasties at The Hospital for Special Surgery. At an average follow-up of 2.5 years (range, 2 to 5), the overall recurrence rate of infection was 3.8 per cent. Only one (2.0 per cent) infection occurred where the bacteria were sensitive to PG and there were no infections in the two-stage reimplantation group. There have been no adverse effects from the gentamicin and the inferior intrusion properties of the PG have not been reflected in the clinical or radiographic results.

Prolonged suppression of infection in total hip arthroplasty

Nineteen periprosthetic infections after total hip arthroplasty were treated with prolonged suppressive antibiotics without removing the components. In 11, antibiotic therapy was monitored with serum bactericidal titers. Eleven had incision and drainage. Indications included patients' refusal of removal or medical contraindications to surgery. Requirements included well-fixed components, highly sensitive organisms, and no systemic sepsis. The follow-up period averaged 4.1 years after treatment. Nine hips showed no deterioration. Seven prostheses failed, five with progressive hip sepsis. Three patients had increasing symptoms without prosthesis removal. Although two-stage reimplantation is preferred, suppressive antibiotics and prosthesis retention can succeed in some patients and may be considered in old, frail patients with an early infection caused by bacteria responsive to oral antibiotic therapy. Suppressive therapy may also be considered for an otherwise compliant patient who refuses removal of an infected prosthesis. The organism must be sensitive to oral antibiotics, and the patient must be tolerant of the antibiotics.

Comparison of ceforanide and cephalothin prophylaxis in patients undergoing total joint arthroplasty

One hundred one patients undergoing total hip and knee arthroplasty were randomly assigned to receive either two 1 gm doses of ceforanide or five doses of cephalothin perioperatively. Simultaneous plasma and cancellous bone specimens were obtained intraoperatively and assayed for antibiotic concentration. Ceforanide plasma and bone levels remained sustained over six hours. Cephalothin plasma and bone levels obtained three to four hours post administration were 91% lower than levels obtained one hour post-dose. Patients were examined for infection for up to 18 months following surgery. None of the patients developed an infected implant. The sustained plasma and bone levels achieved with ceforanide obviate the need for intraoperative dosing necessary with other agents.

Reimplantation in infection. Elution of gentamicin from cement and beads

A prospective study was performed to evaluate the arthroplasty fluid, serum, and urine antibiotic levels in 38 patients implanted with gentamicin-impregnated cement and in 18 patients with gentamicin-impregnated beads. Radioimmune assays were performed on arthroplasty fluid, serum, and urine samples at various times after surgery. On day 1, high arthroplasty fluid levels of gentamicin were eluted from bead-implanted patients (mean, 36.9 micrograms/ml; range, 19.6-69.5) and cement-implanted patients (mean, 14.9 micrograms/ml; range, 2.7-38.9) with very low serum and urine levels. The arthroplasty levels of gentamicin obtained in bead-implanted patients on day 1 were 17 times higher, and in cement-implanted patients, seven times higher, than those obtained with intravenous administration of gentamicin. The serum and urine levels were approximately ten to 20 times less in patients with gentamicin-impregnated cement or beads compared to those levels obtained after intravenous administration. These very low systemic levels should preclude nephrotoxic and ototoxic effects. No toxic effects were observed in these patients. Bioactivity of gentamicin in the specimens was confirmed. Staphylococci were exquisitely sensitive, while Streptococci were moderately resistant to gentamicin. Both gentamicin-impregnated beads and cement appear safe and provide substantial local in vivo antibacterial activity.

Clinical and microbial features of prosthetic joint infection

A one-year experience with prosthetic joint infection, in which 63 cases were identified, is reviewed. Thirty cases (48 percent) were early infections, in the first postoperative year, and 33 cases (52 percent) were late, occurring more than one year after implantation. Pain was the predominant symptom, but clinical clues suggesting infection were frequently absent, with fever in 43 percent and leukocytosis in only 10 percent. The radiographic appearance was more frequently abnormal in late infections (67 versus 37 percent, p less than 0.02). Staphylococci were predominant organisms, constituting 59 percent of prosthetic joint infections, and S. epidermidis was the predominant species in both early and later infections. Of the hematogenous infections, 11 of 13 occurred in the group with late infections; these were mostly nonstaphylococcal . Antigenic proteins of S. epidermidis were characterized by gel electrophoresis, but no infection-specific antigens could be identified when patient serum was compared with normal samples. Precipitating antibodies to the extracellular proteins of S. epidermidis were present in 50 percent of patients with S. epidermidis prosthetic joint infections, 27 percent of patients with nonstaphylococcal infections, 20 percent of patients with S. aureus infections, and 11 percent of normal subjects. In view of the increasing importance of prosthetic joint infection, further study of the pathogenesis of the infection and the host immune response is warranted.

Localized renal aspergillosis with hairy cell leukemia: a review of urinary tract aspergillosis in malignant and nonmalignant conditions

A case of extensive unilateral renal aspergillosis in a man with hairy cell leukemia is described. This case report is unique because of the long duration of the infection that is more characteristic of patients without malignancy. The degree of unilateral renal involvement found, which included invasion of kidney parenchyma, is uncommon in patients with malignancy. Such patients typically have diffuse disseminated disease with microabscesses. The literature on urinary tract aspergillosis in patients with and without underlying malignancy is reviewed.

Two-stage reimplantation for the salvage of infected total knee arthroplasty

The results of eleven two-stage reimplantations to salvage eleven infected total knee arthroplasties in ten women (seven with osteoarthritis and three with rheumatoid arthritis) were evaluated after an average follow-up of thirty-four months. The staged procedures included removal of all of the components of the prosthesis and all cement, then six weeks of parenteral antibiotic therapy (monitored by maintaining serum bactericidal levels at a peak dilution of 1:8), and finally reimplantation with a total condylar-type prosthesis. All antibiotics were discontinued after reimplantation. At follow-up, no patient had had a recurrence of the original infection, but one had a hematogenous infection with a different organism secondary to an infected bunion. The results after reimplantation were rated excellent in five knees, good in four, and fair in two. Weakness of the extensor mechanism with an extension lag was the most frequent complication. We do not believe that antibiotic therapy alone is adequate for the management of an infection around a prosthesis. The method described appears to be effective but it is costly and time-consuming. The surgical procedures and medical management are technically difficult, often special equipment and a custom-made prosthesis are required, and there are no shortcuts.

Reimplantation in infection: a 12-year experience

Three groups of patients underwent reimplantation for infected hip prostheses during the period from 1968 to 1979. The first group (N = 19) was diagnosed mainly by hip aspiration and treated with antibiotics selected by disc sensitivity and one-stage reimplantation in 14 hips. The second group (N = 26) was diagnosed by strict hip infection criteria and treated with a similar antibiotic regimen. Reimplantation was performed in one stage in 13 patients and in two stages in the remaining 13. The third group (N = 16) was diagnosed by the same criteria but treated with standardized bactericidal antibiotics evaluated by the tube dilution method. There were five one-stage reimplantations, ten two-stage, and one radical debridement without removal of components. The follow-up period ranged from two to 12 years. The present guidelines for reimplantation include subacute hip sepsis caused by susceptible bacteria, according to tube dilution methods in immunocompetent patients with adequate soft tissue and bone stock to allow a satisfactory biomechanical reconstruction. Patients should be aware of the risk of recurrence of infection, persistent pain, limited durability, and further surgical treatment.

Infection rates after 3175 total hip and total knee replacements performed with and without a horizontal unidirectional filtered air-flow system

To determine the effect of the ventilation system on infection rates after total hip and total knee arthroplasties performed in operating rooms with and without a horizontal unidirectional filtered air-flow system, using modern antiseptic conditions and antibiotic prophylaxis, all of the single-stage procedures (3175 of a total of 4769) were subjected to statistical analysis and fifty-seven matched pairs for controls were established. A reduced infection rate after total hip replacement (from 1.4 to 0.9 per cent) and an increased infection rate after total knee replacement (from 1.4 to 3.9 per cent) were found when patients operated on in the filtered laminar air-flow operating room were compared with those whose operations were done in two conventional rooms. This pattern was statistically significant and was believed to be due to the positions of the operating team and of the wound with respect to the air flow. Prospectively accumulated factors (such as the experience of the surgeon, the duration of surgery, the diagnosis, and the patient's age) as well as retrospectively accumulated factors (such as predisposing conditions of the patient) did not explain the observed patterns of infection.

Comparative study of diarrhea associated with clindamycin and ampicillin therapy

The incidence of diarrhea associated with clindamycin and ampicillin was studied prospectively among 606 adult inpatients during a 12-month period. Clindamycin was administered to 288 patients of whom 145 received clindamycin in combination with ampicillin. A comparable group of 318 patients received ampicillin alone. Underlying diseases, diets and medications other than antibiotics studied were implicated in the etiology of diarrhea in 25--40% of patients. The incidence of diarrhea due to ampicillin and clindamycin was 3.8 and 4.2%, respectively (P greater than 0.05). The incidence of diarrhea in patients who received both drugs was 9.0% (P less than 0.05). Diarrhea which developed after completion of antibiotic therapy was two-to-three fold longer in duration than that which occurred during drug administration. This finding underscores the necessity to follow patients closely for at least four to six weeks after receiving such medications.

Testicular cultivation of Treponema pallidum (Nichols strains) facilitated by sustained-release steroid administration

Treponema pallidum cultivation is facilitated by substitution of methylprednisolone acetate suspension for hydrocortisone administration during rabbit testicular infection. Methylprednisolone suspension reduces testicular mononuclear cell infiltration and should benefit future studies of virulent T. pallidum.