Background: This prospective investigation was designed to determine if the postoperative infection rate in instrumented lumbar spinal fusion is affected by postoperative antibiotic use. Methods: Two hundred sixty-nine patients were randomized into either a preoperative only protocol or preoperative with an extended postoperative antibiotic protocol. The preoperative only protocol received a single dose of cefazolin IV. The extended postoperative antibiotic protocol received the same preoperative dose plus postoperative cefazolin IV every 8 hours for 3 days followed by oral cephalexin every 6 hours for 7 days. Because of untoward drug reaction or deviation from the antibiotic protocol, 36 of the 269 patients were eliminated from the study. Therefore, 233 patients completed the entire study. Results: There was no significant difference in infection rates between the 2 antibiotic protocols. The postoperative infection rates were 4.3% for the preoperative only protocol and 1.7% for the preoperative with extended antibiotic protocol. The overall postoperative infection rate was 3%. However, 5 variables of blood transfusion, electrophysiologic monitoring, increased height, increased weight, and increased body mass index appeared to demonstrate a trend toward increase in infection rate. Increased tobacco use trended toward a lower infection rate. Conclusion: Statistical significance was not proven in this prospective study comparing single-dose preoperative antibiotic protocol vs preoperative with an extended postoperative antibiotic protocol. A larger study of 1400 patients would possibly provide more statistically significant information.

Background. Culture-negative (CN) prosthetic joint infection (PJI) has not been well studied. We performed a retrospective cohort study to define the demographic characteristics and determine the outcome of patients with CN PJI. Methods. All cases of CN total hip arthroplasty and total knee arthroplasty infections (using a strict case definition) treated at our institution from January 1990 through December 1999 were analyzed. Kaplan-Meier survival methods were used to determine the cumulative probability of success. Results. Of 897 episodes of PJI during the study period, 60 (7%) occurred in patients for whom this was the initial episode of CN PJI. The median age of the cohort was 69 years (range, 36–87 years). Patients had received a prior course of antimicrobial therapy in 32 (53%) of 60 episodes. Of the 60 episodes, 34 (57%), 12 (20%), and 8 (13%) were treated with 2-stage exchange, debridement and retention, and permanent resection arthroplasty, respectively. The median duration of parenteral antimicrobial therapy was 28 days (range, 0–88 days). Forty-nine (82%) of 60 episodes were treated with a cephalosporin. The 5-year estimate of survival free of treatment failure was 94% (95% confidence interval, 85%–100%) for patients treated with 2-stage exchange and 71% (95% confidence interval, 44%–100%) for patients treated with debridement and retention. Conclusions. CN PJI occurs infrequently at our institution. Prior use of antimicrobial therapy is common among patients with CN PJI. CN PJI treated at our institution is associated with a rate of favorable outcome that is comparable to that associated with PJI due to known bacterial pathogens.

Background. Spinal implant infections provide unique diagnostic and therapeutic challenges. Methods. We conducted a retrospective cohort study to evaluate risk factors for treatment failure in patients with early- and late- onset spinal implant infections at the Mayo Clinic (Rochester, MN) during 1994–2002. Results. We identified 30 patients with early-onset spinal implant infection and 51 patients with late-onset spinal implant infection. Twenty-eight of 30 patients with early-onset infection were treated with debridement, implant retention, and antimicrobial therapy. The estimated 2-year cumulative probability of survival free of treatment failure for patients with early-onset infection was 71% (95% confidence interval [CI], 51%–85%). Thirty-two of 51 patients with late-onset infection were treated with implant removal. Their estimated 2-year cumulative probability of survival free of treatment failure was 84% (95% CI, 66%–93%). For patients with early-onset infections, receiving oral antimicrobial suppression therapy was associated with increased cumulative probability of survival (hazard ratio, 0.2; 95% CI, 0.1–0.7). For patients with late-onset infections, implant removal was associated with increased cumulative probability of survival (hazard ratio, 0.3; 95% CI, 0.1–0.7). Conclusions. Early-onset spinal implant infections are successfully treated with debridement, implant retention, and parenteral followed by oral suppressive antimicrobial therapy. Implant removal is associated with successful outcomes in late-onset infections.

Intra-operative incidental contamination of surgical wounds is not rare. Povidone-iodine solution can be used to disinfect surgical wounds. Although povidone-iodine is a good broad-spectrum disinfecting agent, it has occasionally been reported to have a negative effect on wound healing and bone union. Therefore, its safety in a spinal surgery is unclear. A prospective, single-blinded, randomized study was accordingly conducted to evaluate the safety of povidone-iodine solution in spinal surgeries. Ascertained herein was the effect of wound irrigation with diluted povidone-iodine solution on wound healing, infection rate, fusion status and clinical outcome of spinal surgeries. Materials and methods: From January 2002 to August 2003, 244 consecutive cases undergoing primary instrumented lumbosacral posterolateral fusion due to degenerative spinal disorder with segmental instability had been collected and randomly divided into two groups: the study group (120 cases, 212 fusion levels) and the control group (124 cases, 223 fusion levels). Excluded were those patients with a prior spinal surgery, spinal trauma, malignant tumor, infectious spondylitis, rheumatoid arthritis, ankylosing spondylitis, metabolic bone disease, skeletal immaturity or with an immunosuppressive treatment. In the former group, wounds were irrigated with 0.35% povidone-iodine solution followed by normal saline solution just before the bone-grafting and instrumentation procedure. However, only with normal saline solution in the latter. All the operations were done by the same surgeon with a standard technique. All the patients were treated in the same postoperative fashion as well. Later on, wound healing, infection rate, spinal bone fusion and clinical outcome were evaluated in both groups. Results: A significant improvement of back and leg pain scores, modified Japanese Orthopedic Association function scores (JOA) and ambulatory capacity have been observed in both groups. One hundred and seven patients in the study group and one hundred and nine in the control group achieved solid union. There was no infection in the study group but six deep infections in the control group. Wound dehiscence was noted in one group 1 and two group 2 patients. A subsequent statistical analysis revealed higher infection rate in the control group (P<0.05), but no significant difference in fusion rate, wound healing, improvement of pain score, function score and ambulatory capacity between the two groups. Conclusion: Diluted povidone-iodine solution can be used safely in spinal surgeries, and it will not influence wound healing, bone union and clinical outcome.

Eight patients with shoulder sepsis were treated with staged exchange arthroplasty using antibiotic-impregnated polymethyl methacrylate spacers shaped and fitted to the patient's anatomy after extensive joint débridement. Intravenous antibiotic therapy followed for a minimum of 3 months. At the end of 6 months, the patients were evaluated for any clinical or laboratory signs of infection; none were encountered. Exchange prosthetic reconstructions were performed using standard implants fixed with antibiotic-impregnated polymethyl methacrylate cement. Three patients underwent a revision to total shoulder arthroplasty, whereas 5 underwent hemiarthroplasty of the humerus with local capsular flap covering of the glenoid. All patients experienced substantial pain relief and improvement in function despite limited total overhead motion, showing this technique to be a satisfactory salvage procedure for managing sepsis of the glenohumeral joint primarily and after total shoulder arthroplasty.