Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Symposium: Papers Presented at the 2008 Meeting of the Musculoskeletal Infection Society 14 articles

Articles

Periprosthetic Infection Due to Resistant Staphylococci: Serious Problems on the Horizon

Javad Parvizi MD, FRCS, Khalid Azzam MD, Elie Ghanem MD, Matthew S. Austin MD, Richard H. Rothman MD, PhD Prosthetic joint infections (PJI) caused by methicillin-resistant staphylococci represent a major therapeutic challenge. We examined the effectiveness of surgical treatment in treating infection of total hip or knee arthroplasty caused by methicillin-resistant staphylococcal strains and the variables influencing treatment success. One hundred and twenty-seven patients were treated at our institution between 1999 and 2006. There were 58 men and 69 women, with an average age of 66 years. Patients were followed for a minimum of 2 years or until recurrence of infection. Débridement and retention of the prosthesis was performed in 35 patients and resection arthroplasty in 92. Débridement controlled the infection in only 37% of cases whereas two-stage exchange arthroplasty controlled the infection in 75% of hips and 60% of knees. Preexisting cardiac disease was associated with a higher likelihood of failure to control infection in all treatment groups. Antibiotic-resistant Staphylococci continue to compromise treatment outcome of prosthetic joint infections, especially in patients with medical comorbidities. New preventive and therapeutic strategies are needed.,[object Object]

Hand-mixed and Premixed Antibiotic-loaded Bone Cement Have Similar Homogeneity

Alex C. McLaren MD, Matt Nugent MD, Kostas Economopoulos MD, Himanshu Kaul BSE, Brent L. Vernon PhD, Ryan McLemore PhD Since low-dose antibiotic-loaded bone cement (ALBC) was approved by the FDA for second-stage reimplantation after infected arthroplasties in 2003, commercially premixed low-dose ALBC has become available in the United States. However, surgeons continue to mix ALBC by hand. We presumed hand-mixed ALBC was not as homogeneous as commercially premixed ALBC. We assessed homogeneity by determining the variation in antibiotic elution by location in a batch, from premixed and hand-mixed formulations of low-dose ALBC. Four hand-mixed methodologies were used: (1) suspension—antibiotic powder in the liquid monomer; (2) no-mix—antibiotic powder added but not mixed with the polymer powder before adding monomer; (3) hand-stirred—antibiotic powder stirred into the polymer powder before the monomer was added; and (4) bowl-mix—antibiotic powder mixed into polymer powder using a commercial mixing bowl before the monomer was added. Antibiotic elution was measured using the Kirby-Bauer bioassay. None of the mixing methods had consistently dissimilar homogeneity of antibiotic distribution from the others. Based upon our data we conclude hand-mixed low-dose ALBC is not less homogeneous than commercially premixed formulations.

Topographic Features Retained after Antibiotic Modification of Ti Alloy Surfaces: Retention of Topography with Attachment of Antibiotics

Constantinos Ketonis BS, Javad Parvizi MD, Christopher S. Adams PhD, Irving M. Shapiro DDS, PhD, Noreen J. Hickok PhD [object Object]

Patients with Prosthetic Joint Infection on IV Antibiotics are at High Risk for Readmission

Anurag Duggal MD, Wael Barsoum MD, Steven K. Schmitt MD Due to the rise in prosthetic joint implantations, prosthetic joint infections (PJI) are increasing. Most PJI are treated outside the hospital setting via community-based parenteral antiinfective therapy (CoPAT) after initial surgical management, although little is reported about the short-term complications of CoPAT. We therefore ascertained the numbers of unanticipated readmissions, unplanned surgeries, and CoPAT complications within 12 weeks of hospital discharge in patients with PJI on CoPAT. We retrospectively reviewed the charts of 74 patients with PJI. Twenty-seven (73% of readmitted patients) were for unanticipated reasons within 12 weeks of hospital discharge; 16 (43% of readmitted) underwent an unplanned surgery. Nine patients (12% of total cohort) had CoPAT-related adverse events. Our data suggest patients with PJI on CoPAT represent a complex cohort that needs to be monitored closely for complications early after hospital discharge.,[object Object]

Hip Disarticulation for Severe Lower Extremity Infections

Charalampos G. Zalavras MD, Nick Rigopoulos MD, Elke Ahlmann MD, Michael J. Patzakis MD Hip disarticulation is rarely performed for infections and variable mortality rates have been reported. We determined the number of deaths following hip disarticulation for severe lower extremity infections in 15 patients. Indications for hip disarticulation were necrotizing soft tissue infections in seven patients and persistent infections of the proximal thigh in eight patients. The most common microorganism was Staphylococcus aureus, present in eight patients. Hip disarticulation was performed emergently in seven patients and electively in eight patients. All patients survived the operation and at 1 month postoperatively 14 of 15 patients were alive. Hip disarticulation for these severe infections had high survival, even when performed emergently for life-threatening infections. We believe hip disarticulation is a reasonable option treating severe infections of the lower extremity and should be part of the armamentarium of the orthopaedic surgeon.,[object Object]

Effectiveness of Antimicrobial Incise Drapes versus Cyanoacrylate Barrier Preparations for Surgical Sites

Sepehr Bady MD, Montri D. Wongworawat MD Surgical wound infections are one of the leading causes of morbidity and mortality in surgical patients. We compared the effectiveness of antimicrobial incise drapes versus cyanoacrylate microbial sealant adhesive barrier in preventing skin flora contamination of surgical wounds in an animal model. Staphylococcus aureus in suspension was placed on fresh ovine skin across 60 circular marks of defined area: 20 circles were designated as controls, 20 were covered with antimicrobial incise drapes, and 20 were covered with cyanoacrylate. Incisions were made through the circles; swab cultures were taken, serially diluted after agitation, and cultured on blood agar plates. The number of colony forming units (CFUs) was then counted and compared between the samples from the two drapes. While there were no differences between antimicrobial incise-draped areas (108.3 ± 90 CFUs) and undraped controls (82.7 ± 93.3 CFUs), the cyanoacrylate-treated group demonstrated lower wound bed contamination (0.3 ± 0.6 CFUs) when compared to controls.

Magnetic Resonance Imaging Findings in Hematogenous Osteomyelitis of the Hip in Adults

Charalampos G. Zalavras MD, Nick Rigopoulos MD, John Lee MD, Thomas Learch MD, Michael J. Patzakis MD Hematogenous hip infections are rare in adults and the extent of infection into the bone or adjacent soft tissues may be underestimated, leading to inadequate surgical débridement. Using MRI, we sought to determine the extent of bone involvement and the presence of adjacent soft tissue abscesses in adults with hip osteomyelitis. We reviewed the records and MRIs in 11 adult patients (12 hips) with hematogenous osteomyelitis of the femoral head in 12 hips. Ten of 11 patients had one or more comorbidities. All patients underwent surgical débridement and received antibiotic therapy for 6 weeks. MRI revealed osteomyelitis distal to the femoral head in seven of 12 hips with extension into the medullary canal in three of these seven. Femoral head erosions were present in 10 hips, acetabulum osteomyelitis in 11, and acetabular erosions in six hips. Infection extended into adjacent soft tissues in eight of 12 hips. MRI demonstrated that the infection may extend distal to the femoral head or into the adjacent soft tissues. MRI may be useful for preoperative planning so that all regions affected by the infection can be treated.,[object Object]

Infection Following Operative Treatment of Ankle Fractures

Charalampos G. Zalavras MD, Thomas Christensen MD, Nikolaos Rigopoulos MD, Paul Holtom MD, Michael J. Patzakis MD

Information on the microbiology of infections after operative ankle fractures, on the details of a treatment protocol used when the ankle joint is preserved, and on the outcome of this protocol will be helpful for the physicians managing patients with this complex problem. We therefore determined the most common pathogen of these infections, the infection recurrence rate, and the amputation rate. We retrospectively reviewed 26 patients of a mean age of 43 years with infections following operative treatment of ankle fractures. Twenty-one of 26 patients (81%) were compromised hosts according to the Cierny-Mader classification. Patients presenting up to 10 weeks postoperatively were treated by débridement and either hardware retention (if implants were judged stable) or hardware removal (if implants were loose). All patients presenting more than 10 weeks postoperatively underwent débridement and hardware removal, with the exception of one patient who underwent below knee amputation. Staphylococcus aureus was identified in 17 patients (65%) and was oxacillin-resistant in six (23%). The infection recurred in five of 18 patients who were followed up for 8 months on average. Three recurrent infections were controlled with repeat débridement. The remaining two patients underwent below-knee amputation, resulting in amputations in 3 of 18 patients. Infection after operative treatment of ankle fractures is a limb-threatening complication, especially in patients with comorbidities, such as diabetes mellitus. Treatment is challenging with high infection recurrence and amputation rates.,[object Object]

Staged Revision for Knee Arthroplasty Infection: What Is the Role of Serologic Tests Before Reimplantation?

Elie Ghanem MD, Khalid Azzam MD, Mark Seeley MD, Ashish Joshi MD, MPH, Javad Parvizi MD, FRCS Erythrocyte sedimentation rate and C-reactive protein are common preoperative diagnostic markers for prosthetic joint infection but their prognostic role before reimplantation has yet to be defined. We therefore determined the prognostic value of erythrocyte sedimentation rate and C-reactive protein performed before second-stage reimplantation for the treatment of infected total knee arthroplasty (TKA). We studied 109 patients who had undergone two-stage revision TKA for sepsis from 1999 to 2006. Receiver operating characteristic curves were constructed to determine the discriminatory value of erythrocyte sedimentation rate and C-reactive protein before reimplantation in predicting persistent infection. Twenty-three of the 109 patients (21%) required revision surgery for recurrence of prosthetic joint infection. The receiver operating characteristic areas under the curve suggested erythrocyte sedimentation rate and C-reactive protein poorly predicted persistent infection after TKA reimplantation. Cutoff values could not be obtained because of the high variance. We reached similar conclusions regarding the change in erythrocyte sedimentation rate and C-reactive protein levels from time of resection. More accurate diagnostic tools are needed to support clinical judgment in monitoring infection progress and thus deciding whether to proceed with TKA reimplantation.,[object Object]

Diabetes Associated with Increased Surgical Site Infections in Spinal Arthrodesis

Sam Chen MD, Matt V. Anderson BS, Wayne K. Cheng MD, Montri D. Wongworawat MD Diabetes mellitus (DM) is a major risk factor for surgical site infection (SSI). Spinal surgeries are also associated with an increased risk of SSI. To confirm previous reports we evaluated the association of DM with spine infection in 195 patients who underwent elective posterior instrumented lumbar arthrodesis over a 5-year period: 30 with DM and 165 without. Other known risk factors for SSI in spinal surgery were examined: age, gender, tobacco use, body mass index, American Society of Anesthesiologists (ASA) class, intraoperative antibiotic redosing, surgical time, bone allograft use, estimated blood loss (EBL), and drain use. The adjusted relative risk of having DM for developing SSI was 4.10 (95% C.I. = 1.37–12.32). Other factors did not appear as risk factors for SSI. The data confirm DM is a risk factor for surgical site infections in spinal arthrodesis surgery.,[object Object]

Outcome of a Second Two-stage Reimplantation for Periprosthetic Knee Infection

Khalid Azzam MD, Kevin McHale BA, Matthew Austin MD, James J. Purtill MD, Javad Parvizi MD Recurrent or persistent infection after two-stage exchange arthroplasty for previously infected total knee replacement is a challenging clinical situation. We asked whether a second two-stage procedure could eradicate the infection and preserve knee function. We evaluated 18 selected patients with failed two-stage total knee arthroplasty implantation treated with a second two-stage reimplantation between 1999 and 2005. Failure of treatment was defined as recurrence or persistence of infection. The minimum followup was 24 months (mean, 40 months; range, 24–83 months). Recurrent or persistent infection was diagnosed in four of 18 patients, two of whom were successfully treated with a third two-stage exchange arthroplasty. Knee Society score questionnaires administered at the last followup showed an average Knee Society knee score of 73 points (range, 24–100 points) and an average functional score of 49 points (range, 20–90 points). The data suggest repeat two-stage exchange arthroplasty is a reasonable option for eradicating periprosthetic infection, relieving pain, and achieving a satisfactory level of function for some patients.,[object Object]