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Background A two-stage revision total knee arthroplasty is recognized as the gold standard in the treatment of infection. However, traditional spacers limit function in the interval between the two stages and may cause instability, scarring, and bone erosion. The PROSTALAC knee spacer is an antibiotic-loaded cement articulating spacer that allows some movement of the knee between stages. Whether motion enhances long-term function is unknown. Questions/purposes We therefore identify the rate of control of infection using the PROSTALAC exchange spacer and to assess the clinical outcome after implantation with a definitive implant. Methods We retrospectively reviewed 115 knees that underwent two-stage exchange with the PROSTALAC spacer. Forty-eight of these had a minimum followup of 5 years (mean, 9 years; range, 5–12 years). Results At last review, 101 of the 115 knees (88%) had no evidence of infection. Of the 14 knees that became reinfected, four were from the same organism and 10 were with a different organism. After further intervention, using the two-stage approach again, the infection was controlled in 12 of the 14 initially reinfected cases, resulting in a failure to cure in only two cases. We observed improvements in mean WOMAC, Oxford, UCLA, and Patient Satisfaction scores at last review. Conclusions The PROSTALAC functional spacer was associated with a 98% rate of control of infection and improvements in the quality-of-life outcomes in the treatment of chronically infected total knee arthroplasties. Level of Evidence Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background Two-stage exchange arthroplasty is the gold standard for treatment of infected TKA. The erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and synovial fluid white blood cell (WBC) count with differential are often used to determine treatment response; however, it is unclear whether these tests can answer the critical question of whether joint sepsis has been controlled between stages and if reimplantation is indicated. Questions/purposes We therefore asked if (1) these serologies respond between stage one explantation and stage two reimplantation during two-stage knee reconstruction for infection; and (2) changes in the values of these serologies are predictive of resolution of joint infection. Methods We retrospectively reviewed the serologies of 76 infected patients treated with a two-stage exchange protocol. The ESR, CRP, and aspiration were repeated a minimum of 2 weeks following antibiotic cessation and prior to second stage reoperation. Comparisons were made to identify trends in these serologies between the first and second stage procedures. Results Eight knees (12%) were persistently infected at the time of second stage reoperation. The ESR remained persistently elevated in 37 knees (54%), and the CRP remained elevated in 14 knees (21%) where infection had been controlled. We were unable to identify an optimum cutoff value for the ESR, CRP, or the two combined. The best test for confirmation of infection control was the synovial fluid WBC count. Conclusions Although the ESR, CRP, and synovial fluid WBC counts decreased in cases of infection control, these values frequently remained elevated. We were unable to identify any patterns in these tests indicative of persistent infection. Level of Evidence Level II, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.

Background Open débridement with polyethylene liner exchange (ODPE) remains a relatively low morbidity option in acute infection of total knee arthroplasty (TKA), but concerns regarding control of infection exist. We sought to identify factors that would predict control of infection after ODPE. Methods We identified 44 patients (44 knees) with culture-positive periprosthetic infection who underwent ODPE. Failure was defined as any reoperation performed for control of infection or the need for lifetime antibiotic suppression. Patients had been followed prospectively for a minimum of 1 year (mean, 5 years; range, 1–9 years). Results Twenty-five of the 44 patients (57%) failed ODPE. Of these 25 patients, two had one additional procedure, 21 had more than one additional procedure, and two required lifetime antibiotic suppression. Failure rates tended to differ based on primary organism: 71% of Staphylococcus aureus periprosthetic infection failed versus 29% of Staphylococcus epidermidis, although with the limited numbers theses differences were not significant. Age, gender, or measures of comorbidity did not influence the risk of failure. There was no difference in failure rate (58% versus 50%) when the ODPE was performed greater than 4 weeks after index TKA. After a failed ODPE, 19 of the 25 failures went on to an attempted two-stage revision procedure. In only 11 of these 19 cases was the two-stage revision ultimately successful. Conclusions Eradication of infection with ODPE in acute TKA infections is unpredictable; certain factors trend toward increased success but no firm algorithm can be offered. The success of two-stage revision for infection may be diminished after a failed ODPE. Level of Evidence Level III, retrospective comparative study. See Guidelines for Authors for a complete description of levels of evidence.

Background Methicillin-resistant hip infections are increasingly common. Reports of the surgical management of these patients using two-stage THA show variable control of infection, but all reports used static spacers. Questions/purposes We therefore determined (1) the rate of successful control of infection and (2) function in patients with methicillin-resistant infection treated with a two-stage THA using an articulated cement spacer during the first stage. Methods We retrospectively reviewed 50 patients who had a two-stage revision THA for methicillin-resistant Staphylococcus aureus or methicillin-resistant Staphylococcus epidermidis infection. Twelve patients died, leaving 38 for review. All eligible patients completed quality-of-life outcome questionnaires (WOMAC, SF-12, Oxford-12, UCLA activity score, hip and knee satisfaction score). Minimum followup was 24 months after the second stage (mean, 58 months; range, 24–123 months). Results Of the 38 patients, eight (21%) had recurrence of their infection requiring further revision surgery. Of the remaining 27 patients, the mean WOMAC was 62, mean Oxford-12 60, mean UCLA activity score 4.3, and mean hip and knee satisfaction score 66. Conclusions We found a treatment failure rate of 21% for patients with methicillin-resistant S. aureus or methicillin-resistant S. epidermidis infection. This is a higher rate than reported for two-stage THA for studies including patients infected with both nonresistant and resistant organisms. The functional scores for patients were also lower than those reported in the literature. Level of Evidence Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Background With the trend toward pay-for-performance standards plus the increasing incidence and prevalence of periprosthetic joint infection (PJI), orthopaedic surgeons must reconsider all potential infection control measures. Both airborne and nonairborne bacterial contamination must be reduced in the operating room. Questions/purposes Analysis of airborne bacterial reduction technologies includes evaluation of (1) the effectiveness of laminar air flow (LAF) and ultraviolet light (UVL); (2) the financial and potential health costs of each; and (3) an examination of current national and international standards, and guidelines. Methods We systematically reviewed the literature from Ovid, PubMed (Medline), Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA, NHSEED, CINAHLPLUS, and Google Scholar published until June 2010 focusing on ultraclean air, ultraviolet light, and laminar air. Results High-level data demonstrating substantial PJI reduction of any infection control method may not be feasible as a result of the relatively low rates of occurrence and the expense and difficulty of conducting a large enough study with adequate power. UVL has potentially unacceptable health costs and the Centers for Disease Control and Prevention (CDC) recommends against its use. European countries have standardized LAF and it is used by the majority of American joint surgeons. Conclusions Both LAF and UVL reduce PJI. The absence of a high level of evidence from randomized trials is not proof of ineffectiveness. The historically high cost of LAF has decreased substantially. Only LAF has been standardized by several European countries. The CDC recommends further study of LAF but recommends UVL not be used secondary to documented potential health risks to personnel.

Background Prosthetic joint infection is an uncommon but serious complication of total knee arthroplasty (TKA). Control of infection after TKA is not always possible, and the resolution of infection may require an above-knee amputation (AKA). Questions/purposes The purpose of this study was to determine the etiology of AKA and the functional outcomes of AKA after infected TKA. Methods We retrospectively reviewed 35 patients who underwent AKA after an infected TKA. The amputations were performed an average of 6 years (range, 21 days to 24 years) after primary TKA. There were 19 females and 16 males with a mean age of 62 years (range, 26–88 years). Patient demographic information, comorbidities, surgical treatments, cultures, and culture sensitivities were recorded. Complications and functional status, including SF-12 and activities of daily living questionnaires, after AKA were also studied. The minimum followup was 7 months (mean, 39 months; range, 7–96 months). Results Two patients died secondary to cardiac arrest and 13 more died during the followup period of unrelated causes. Nine patients required irrigation and débridement for nonhealing wounds after AKA and two patients had repeat AKA for bony overgrowth. Of the 14 patients fitted for prostheses, eight were functionally independent outside of the home. Patients fitted with a prosthesis had higher mean activities of daily living scores (58 versus 38) and also tended to be younger with fewer comorbidities than those who were not fitted with a prosthesis. Conclusions We found low functional status in living patients with an AKA after infection with only half of the patients walking after AKA. Level of Evidence Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background Retention treatment is reportedly associated with lower infection control rates than two-stage revision. However, the studies on which this presumption are based depend on comparisons of historical rather than concurrent controls. Questions/purposes We (1) asked whether the infection control rates, number of additional procedures, length of hospital stay, and treatment duration differed between implant retention and two-stage revision treatment; and (2) identified risk factors that can contribute to failure of infection control. Methods We reviewed the records of 60 patients treated for 64 infected TKA from 2002 to 2007. Twenty-eight patients (32 knees) underwent débridement with retention of component, and 32 patients (32 knees) were treated with component removal and two-stage revision surgery. We determined patients’ demographics, type of infection, causative organisms, and outcome of treatment. Mean followup was 36 months (range, 12–84 months). Results Infection control rate was 31% in retention and 59% in the removal group after initial surgical treatment, and 81% and 91% at latest followup, respectively. Treatment duration was shorter in the retention group and there was no difference in number of additional surgeries and length of hospital stay. Type of treatment (retention versus removal) was the only factor associated with infection control; subgroup analysis in the retention group showed Staphylococcus aureus infection and polyethylene nonexchange as contributing factors for failure of infection control. Conclusions Although initial infection control rate was substantially lower in the retention group than the removal group, final results were comparable at latest followup. We believe retention treatment can be selectively considered for non-S. aureus infection, and when applied in selected patients, polyethylene exchange should be performed. Level of Evidence Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background Chronic infections in TKA have been traditionally treated with a two-stage protocol incorporating a temporary antibiotic-loaded cement spacer. The use of a static as opposed to an articulating spacer is controversial. Some surgeons believe a static spacer results in a higher rate of infection eradication, whereas others believe an articulating spacer provides equivalent rates of infection control with improved function between stages and the potential for better eventual range of motion. Questions/purposes We determined the rates of infection control and postoperative function for an articulating all-cement antibiotic spacer fashioned intraoperatively from prefabricated silicone molds. Methods We retrospectively reviewed 60 patients with an infected TKA using the same cement-on-cement articulating spacer. A minimum of 4 g antibiotic per package of cement was used when making the spacer. Complications and pre- and postoperative knee flexion, extension, and Knee Society scores were recorded. Bone loss associated with the spacer was determined radiographically and by intraoperative inspection of the bony surfaces at the second stage. Minimum followup was 24 months (mean, 35 months; range, 24–51 months). Results Seven patients (12%) became reinfected, four with an organism different from that identified at the index resection arthroplasty. One spacer femoral component broke between stages but did not require any specific treatment. We identified no bone loss between stages and no complications related to the cement-on-cement articulation. The mean pretreatment Knee Society scores of 53 improved to 79. The mean preoperative flexion of 90.6º improved to 101.3º at final followup. Conclusions An articulating antibiotic spacer was associated with control of a deep periprosthetic infection in 88% of patients while allowing range of motion between stages. Level of Evidence Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

This Classic article is a reprint of the original work by William S. Baer, MD, The Treatment of Chronic Osteomyelitis With the Maggot (Larva of the Blow Fly). An accompanying biographical sketch on William Baer, is available at DOI 10.1007/s11999-010-1415-4 . The Classic Article is ©1931 by the Journal of Bone and Joint Surgery, Inc. and is reprinted with permission from Baer WS. The treatment of chronic osteomyelitis with the maggot (larva of the blow fly). J Bone Joint Surg Am . 1931;13:438–475.

Background Intraoperative Gram stains have a reported low sensitivity but high specificity when used to help diagnose periprosthetic infections. In early 2008, we recognized an unexpectedly high frequency of apparent false-positive Gram stains from revision arthroplasties. Questions/purposes The purpose of this report is to describe the cause of these false-positive test results. Methods We calculated the sensitivity and specificity of all intraoperative Gram stains submitted from revision arthroplasty cases during a 3-month interval using microbiologic cultures of the same samples as the gold standard. Methods of specimen harvesting, handling, transport, distribution, specimen processing including tissue grinding/macerating, Gram staining, and interpretation were studied. After a test modification, results of specimens were prospectively collected for a second 3-month interval, and the sensitivity and specificity of intraoperative Gram stains were calculated. Results The retrospective review of 269 Gram stains submitted from revision arthroplasties indicated historic sensitivity and specificity values of 23% and 92%, respectively. Systematic analysis of all steps of the procedure identified Gram-stained but nonviable bacteria in commercial broth reagents used as diluents for maceration of periprosthetic membranes before Gram staining and culture. Polymerase chain reaction and sequencing showed mixed bacterial DNA. Evaluation of 390 specimens after initiating standardized Millipore filtering of diluent fluid revealed a reduced number of positive Gram stains, yielding 9% sensitivity and 99% specificity. Conclusions Clusters of false-positive Gram stains have been reported in other clinical conditions. They are apparently rare related to diagnosing periprosthetic infections but have severe consequences if used to guide treatment. Even occasional false-positive Gram stains should prompt review of laboratory methods. Our observations implicate dead bacteria in microbiologic reagents as potential sources of false-positive Gram stains.