Proactive Risk Assessment of Surgical Site Infection in Ambulatory Surgery Centers

Orthopedic Surgery: Examples of Risk Factors Identified in the Literature for SSIs

Generally speaking:

• Studies have shown that smoking is a significant risk factor for SSI.
• Diabetes is a well-known risk factor, as it decreases immune response to nosocomial infections.
• Hyperglycemia and other fluctuation in the levels of blood glucose have been reported as predispositions to SSI's.
• Multiple studies have shown both surgical and anesthesia durations as risk factors.

Preventing Infection in Total Joint Arthroplasty [Matar et al. (2010)]:

While the debate over the risk factors following total joint arthroplasty continue, “the presence of comorbidities, including rheumatoid arthritis, myocardial infarction, atrial fibrillation, and obesity, along with postoperative superficial SSI, an increased duration of surgery, a longer hospital stay, and treatment with a bilateral procedure, are the most commonly cited risk factors for periprosthetic joint infection following total joint arthroplasty” [Matar et al. (2010)].

Infection rate and risk factor analysis in an orthopaedic ambulatory surgical center, Edmonston DL, Foulkes GD., J Surg Orthop Adv., 19, pp 173-176, 2010.

Aims

• To determine the rate of infection and identify patient and risk factors for SSI in an orthopaedic ASC.

Methods

• 11,333 patients undergoing orthopaedic surgery at Macon Outpatient Surgery between January 2002 and March 2007 were included in the study. [In order to obtain a 95% confidence level, a ±5% confidence interval and a statistical power of at least 0.80, the control group size included 372 patients.]

Results

• 37 infections for 11,333 patients, leading to an SSI rate of 0.33%.
• Of the ten risk factors evaluated, 5 had a statistically significant level of positive association with SSI: Male sex, smoking, diabetes, surgery time, anesthesia time.
• Male sex, smoking, and diabetes demonstrated significantly higher risk for infection (Table 1). Surgery time and duration of anesthesia administration were also associated statistically with SSI. A history of cancer, hypertension, or thyroid problems were all associated with higher but statistically insignificant risk of SSI. Patient age and number of past surgeries were equal in the SSI and control groups.
• Males may be more likely to present with open, traumatic, or more contaminated wounds than females. Also there may be an increased need to shave preoperative sites, and also personal hygiene.

Early Wound Complication of Operative Treatment of Calcaneus Fractures: Analysis of 190 Fractures, Folk, JW, Starr, AJ, Early, JS, 1999.

Aims

• To discover any associations between preoperative variables and the occurrence of wound complications in the surgical treatment of calcaneus fractures.

Conclusions

• Open fracture or a history of diabetes both lead to a higher relative risk of a wound complication than does smoking.

Surgical Site Infection Complicating Internal Fixation of Fractures: Incidence and Risk Factors [Thanni et al. (2004)]

Aims

• To determine the incidence and risk factors for SSIs following internal fixation of fracture.

Methods

• A cohort of 90 patients with long bone fractures that were stabilized internally with metallic devices was studied prospectively and retrospectively.

Results

• The incidence of SSI was 12%. The isolated organisms were Staphylococcus aureus in four patients, Pseudomonas spp. in three, and Escherichia coli in one patient. Diabetes mellitus and peroperative transfusion with allogeneic blood were not predictive of SSI. Duration of operation longer than 120 minutes was a strong predictor (OR 2.25, 95% CL 0.48-10.16). Other risk factors were male sex (OR 2.01, 95% CL 0.44-10.45), injury-operation interval less than six months (OR 2.00, 95% CL 0.22-46.08), fracture fixation with plates and screws (OR 1.51, 95% CL 0.36-6.40), white blood cell count (WBC) less than 5,000 per cumm (OR 1.50, 95% CL 0.15-16.37), preoperative urinary cotheterization (OR 1.48, 95% CL 0.00-16.19), and postoperative urinary catheterization (OR 1.24, 95% CL 0.29-5.00).

Conclusion

• The incidence of SSI after internal fixation of long bone fractures in the center is 12%. Important risk factors are: Use of plates and screws, WBC less than 5,000 per cumm, and perioperative urinary catheterization, postoperative urinary catheterization.

Surgical Site Infections in Orthopedic Patients: Prospective Cohort Study [Maksimovic et al. (2008)]

Aims

• To estimate the incidence rate and risk factors of surgical site infections in the orthopedic wards in a major teaching hospital in Serbia.

Methods

• A 6-month prospective cohort study, with 30 days of patient follow-up after surgery, was conducted at the teaching hospital in Belgrade. We collected patient' basic demographic data and data on underlying disease status, surgical procedures, preoperative preparation of patients, and antibiotic prophylaxis. The National Nosocomial Infections Surveillance (NNIS) risk index was computed for each patient. Descriptive and logistic regression analyses were performed to determine risk factors for surgical site infections.

Results

• Assessment of 277 patients after operation revealed surgical site infection in 63 patients. In 3 (4.8%) of them, surgical site infections were detected after hospital discharge. The overall incidence rate of surgical site infections was 22.7% (95% confidence interval [95% CI], 17.5-29.1). The incidence increased from 13.2% in clean wounds to 70.0% in dirty wounds. The rates of surgical site infection for the NNIS risk index classes 0 to 3 were 8.1% (13 of 161), 36.4% (32 of 88), 63.0% (17 of 27), and 100% (1 of 1) (P<0.001; χ² test). Multivariate logistic regression analysis identified the following independent risk factors for surgical site infections: greater number of persons in the operating room (OR, 1.28; 95% CI, 1.02-1.60), contaminated or dirty wounds (OR, 12.09; 95% CI, 5.56-26.28), and American Society of Anesthesiologist' (ASA) score >2 (OR, 3.47; 95% CI, 1.51-7.95). In patients who were shaved with a razor, the period of 12 or more hours between shaving and intervention was also an independent risk factor (OR, 2.77; 95% CI, 1.22-6.28).

Conclusion

• There is a high incidence of SSIs in orthopedic patients in Serbia in comparison with developed countries and some developing countries. Points for intervention could be reduction of personnel during surgery, better treatment of wounds, decreasing ASA score, and reduction of the time between surgical site shaving and the intervention.

Risk Factors for Venous Thromboembolism Andersen, FA, Frederick SA, Circulation, pp I-9–I-16, 2003.

Results

• Risk factors for Venous Thromboembolism (VTE) include malignancy, myocardial infection, congestive Heart or respiratory failure. Additional Risk Factors include prior VTE, age (patients >40 are at significantly increased risk compared to younger patients, and risk doubles with each subsequent decade) and obesity (overweight individuals, whether defined by weight or body mass index, may be at increased risk, but the association of excess weight with VTE is a weak one); immobility, varicose veins; pregnancy and puerperium; oral contraceptives; Antiphospholipid Antibody Syndrome; hereditary VTE risk.

Arthroscopic Surgeries

AMBU-KISS: Quality control in ambulatory surgery, Mlangeni D, Babikir R, Gastmeier P, Daschner F, American Journal of Infection Control, 33, pp 11-14, 2005.

Aims

• To compare SSI rates for 3 indicator procedures in the ASC to those observed in the inpatient setting: (1) Arthroscopic knee surgery, (2) Inguinal hernia, (3) Vein-stripping.

Methods

• German National Reference Center for Surveillance of Nosocomial Infections (NRZ) has been establishing standardized surveillance methods since 1997. A database within the Krankenhaus-Infektions-Surveillance System, OP-KISS module, was created to record SSIs in the hospital setting. The use of CDC definitions is mandatory in the surveillance system. Most institutions stratify patients according to risk factors based on the NNIS-Index. Items in the questionnaire included: patient's age, sex, duration of procedure, CDC's NNIS system for defining SSIs and wound classification, ASA Physical Status Classification System, onset of clinical signs and symptoms of infection, and pathogens isolated.

Results

• An infection rate of 0.09% (7/7931) observed in the subgroup arthroscopic knee surgery; 0.65% (20/3094) for inguinal herniotomy; and 0.38% (19/5020) in vein-stripping procedures (Table 1).
• 80% to 90% of SSIs occur within 15 to 21 days after the surgical procedure.
• Infection control programs have been shown to reduce nosocomial (hospital-acquired) infections by 32-56%.

Infectious and thromboembolic complications of arthroscopic shoulder surgery, Randelli P, Castagna A, Cabitza F, Cabitza P, Arrigoni P, Denti M., J Shoulder Elbow Surg, 19, pp 97-101 2010.

Aims

• To identify infection rates in arthroscopic shoulder surgery. In the literature, infection rates are reported as 0.04% to 3.4%.

Methods

• Survey conducted by The Italian Society for Knee Surgery, Arthroscopy, Sport Traumatology, Cartilage and Orthopaedic Technologies (SIGASCOT).

Results

• The minimum and maximum values observed for the rate of infections are respectively 0.3/1000 and 1.6/1000 procedures for arthroscopies with antibiotic prophylaxis; and 1.6/1000 and 10/1000 for arthroscopies performed without antibiotic prophylaxis (Table 2).
• In 12 patients (80%), the infection occurred after a rotator cuff repair. The remaining infectious complications followed acromioplasty, distal clavicle resection, and arthroscopic-assisted osteosynthesis. The diagnosis was made an average of 15.2 days (range, 3-40 days) after the arthroscopic procedure. Infections were resolved with antibiotic therapy alone in 10 patients or in association with lavage in 5.
• The pathogen was identified in 7 patients, being Staphylococcus aureus in 4 patients and S epidermidis in 3. In these patients, specific treatment was initiated according to the results of the cultures. The mean duration of antibiotic administration for treatment was 18.6 days (range, 5-60 days).
• Bert et al. retrospectively evaluated 2,780 knee arthroscopies. An antibiotic was administered to 30% of these patients 1 hour before the intervention. The percentage of infections was 0.11% (1 in 933) in the group given antibiotic prophylaxis and 0.16% (3 in 1847) in the group not given no such prophylaxis. The authors concluded that although most orthopedic surgeons routinely give antibiotic prophylaxis before arthroscopic surgery, the systematic administration of antibiotics before arthroscopy of the knee does not have an additional effect.

Arthroscopic Surgery of the Shoulder: A General Appraisal, Ogilvie-Harris, DJ, Wiley, AM, 1986.

Results

• Out of 439 patients undergoing arthroscopic surgery of shoulder over a 10-year period, 3% had a complication, including rotator cuff lesions, osteoarthritis, glenoid labrum tears and instability, biceps tendon lesions, loose bodies, synovectomy, sepsis, percutaneous fixation for instability.

Surgical Site Infections after Arthroscopy: Outbreak Investigation and Case Control Study, Babcock, HM et al., Arthroscopy: The Journal of Arthroscopic and Related Surgery, 19, No. 2, pp 172–181, 2003.

Aims

• To determine the causes of increased post-arthroscopy SSIs and to identify the risk factors for infection.

Methods

• Demographic, clinical, and microbiological data were collected on 27 post-arthroscopy SSIs from 1994 through 1999. Risk factors were identified for SSI by case-control analysis. The facility was a 100-bed private hospital associated with a university teaching facility, where approximately 600 arthroscopic surgeries are performed annually.

Results

• Reported rates of infectious complications following arthroscopy range from 0.01% to 0.48%.
• Difficulties for SSI form arthroscopy due to case detection, lack of standardized definitions on infection, and the inability to accrue enough cases in any single center to define risk factors adequately.

• Other difficulties for obtaining SSI infection data are because a patient with an infection may attend a different facility where initial procedure was performed for a follow-up; superficial infections can be treated empirically with antibiotics. Patient variables consisted of age, gender, race, height, weight, history of smoking, and comorbid conditions.
• Process variables consisted of type of anesthesia, disinfection or sterilization techniques, skin preparation routines, antibiotic prophylaxis, procedure type, room, personnel present, duration, intraoperative joint injection, and drain placement.
• Most common symptoms associated with infection were pain and swelling, while less common symptoms included fever and erythema.
• 24 of 27 patients with SSI infection (88.9%) required readmission and underwent reoperation.
• Issues associated with procedures dealt with lack of standardization of skin preparation routines, limited available arthroscopes for use (only two), poor instrument cleaning (also not standardized), excessive traffic in operating room during procedures, and suboptimal post-operation cleaning.
• Resolved issues associated with procedures consisted of the prohibition of flash sterilization, purchasing of more arthroscopes, cleaning of instruments was moved to supply area.
• Patients with infections were more likely to have been given intra-articluar corticosteroid injection intraoperatively.
• Ten health care workers who had higher attendance in infection cases were identified. As part of an investigation, hand and nose cultures were collected and six workers had cultures were colonized with oxacillin-sensitive Staphylococcus aureus. They were then treated and follow-ups were negative.
• Key Recommendations to minimize SSI
  • Routine surveillance for SSI
  • Investigation for increased infection rates
  • Avoid intra-articular corticosteroid injections
  • Limit preoperative razor shaving (Preoperative shaving should be prohibited by everyone except the surgeon performing procedure,SSI rates are highest for razor shaving more than 24 hours before surgery)
  • Limit flash sterilization.

Guideline for Prevention of Surgical Site Infection, 1999, Mangram, Alicia J et al., Infection Control and Hospital Epidemiology, 20, No. 4, pp 250-280, 1999

Aims

• To present the Center for Disease Control and Prevention (CDC)'s recommendations for prevention of surgical site infections.

Results

• Preoperative recommendations
  1. Preparation of the patient
     • Identify and treat all infections remote to the surgical site before elective operation and postpone operation until the infection has resolved
     • Do not remove hair preoperatively unless the hair at or around the incision site will interfere with the operation
     • If hair is removed, remove immediately before operation, preferably with electric clippers
     • Control serum blood glucose levels in all diabetic patients and particularly avoid hyperglycemia perioperatively
     • Encourage tobacco cessation (at minimum, abstain for at least 30 days before elective operation)
     • Do not withhold necessary blood products from surgical patients as a means to prevent SSI
     • Require patients to shower or bathe with an antiseptic agent on at least the night before the operative day
     • Thoroughly wash and clean at and around the incision site to remove gross contamination before performing antiseptic skin preparation
  2. Hand/forearm antisepsis for surgical team members
     • Perform a preoperative surgical scrub for at least 2-5 minutes using an appropriate antiseptic (Scrub hands and forearms up to elbows)
     • After surgical scrub, keep hands up and away from the body
  3. Management of infected or colonized surgical personnel
     • Educate and encourage surgical personnel who have signs and symptoms of a transmissible infection illness to report conditions promptly to their supervisory and occupational health service personnel
     • Obtain appropriate cultures from, and exclude from duty, surgical personnel who have draining skin lesions until infection has been ruled out or personnel have received adequate therapy and infection has resolved
  4. Antimicrobial prophylaxis
     • Administer a prophylactic antimicrobial agent only when indicated, and select it based in its efficacy against most common pathogens causing SSI for specific operation
• Intraoperative recommendations
  1. Ventilation
     • Maintain positive-pressure ventilation in the operating room with respect to the corridors and adjacent areas
     • Do not use UV radiation in the operating room to prevent SSI
  2. Cleaning and disinfection of environmental surfaces
     • When visible soiling or contamination with blood or other bodily fluids of surfaces or equipment, use an EPA-approved hospital disinfectant to clean affected areas
  3. Microbiological sampling
  4. Sterilization of surgical instruments
     • Sterilize all surgical instruments according to published guidelines
     • Perform flash sterilization only for patient care items that will be used immediately. Do not use flash sterilization for reasons of convenience, as an alternative to pursue chasing additional instrument sets, or to save time
  5. Surgical attire and drapes
     • Use surgical gowns and drapes that are effective barriers when wet
     • Change scrub suits that are visibly soiled, contaminated, and/or penetrated by blood or other potentially infectious materials
  6. Asepsis and surgical technique
• Postoperative incision care recommendations
  • Protect with a sterile dressing for 24 to 48 hours postoperatively an incision that has been closed primarily
  • Wash hands before and after dressing changes and any contact with surgical site
  • Educate the patient and family regarding proper incision care, symptoms of SSI, and the need to report such symptoms
• Surveillance recommendations
  • Use CDC definitions of SSI without modification for identifying SSI among surgical inpatients and outpatients
  • For each patient undergoing an operation chosen for surveillance, record those variables shown to be associated with increased SSI risk

Septic arthritis following arthroscopy: Clinical syndromes and analysis of risk factors, Armstrong, RW, Bolding, F, Joseph, R, Available online 29 April 2005.

Abstract

During a 4-year study of 4,256 knee arthroscopies, eighteen patients became infected (infection rate 0.42%). Occurrence of infection was strongly associated with use of long-acting intraarticular intraoperative corticosteroids. Infection was more common among patients with longer surgery operating times, increased numbers of procedures during surgery, prior procedures, and performance of chondroplasty or soft tissue debridement. Subsequent to the study, the infection rate fell to 0.1%. Twenty-four infections were studied (our eighteen plus six other concurrent community cases); twelve were due to Staphylococcus aureus, eleven to coagulase-negative staphylococci, and one to Enterobacter cloacae. Seventy percent of the patients had onset of symptoms within 3 days of surgery. Most patients with coagulase-negative staphylococcal infections had fevers <38.3°C (101°F), negative Gram stains on synovial fluid, normal peripheral leukocyte counts, and somewhat indolent, mild clinical syndromes, while most patients with S. aureus infections had higher fevers, positive synovial Gram stains, peripheral leukocytosis, and more acute and severe clinical syndromes. Knee pain, swelling, and warmth always occurred, but erythema was noted in only 30% of patients. Treatment with 2 weeks of intravenous antibiotics was successful in all but one patient. Long-term results were excellent in sixteen of twenty-two patients.

Complications of Arthroscopy and Arthroscopic Surgery: Results of a National Survey, DeLee, JC, The Journal of Arthroscopic and Related Surgery, 1, pp 214-220, 1985.

Aims

• To estimate the complication rate following arthroscopies.

Methods

• A survey was conducted in 10 geographical regions in the US. The orthopaedic surgeons were asked to fill out a Complications Survey.

Results

• From the literature, Zarins reports that arthroscopy complications occur in 0.1-0.2% of patients; Bunker and Thomas report 0.6% complications.
• In this paper, data was collected on 118,590 arthroscopies, with 930 complications – a complication rate of 0.8%.
• Hemarthrosis was the most common (219 cases, 23.5% of all complications). (Table 1 gives a list of all complications and their respective percentages.)
• Intraarticular infection requiring drainage and antibiotics was reported in 95 cases (10.2% of all complications).
• Equipment failures led to 17% of complications. The average age of the instruments broken was 15.4 months.
• Infections resulted in <90° of motion in 18 of the 95 cases
• Once an infection is suspected, immediate drainage and IV antibiotics are important to restore joint mobility and prevent further cartilage destruction.

Complications in Arthroscopic Surgery Performed by Experienced Arthroscopists, Small, N, The Journal of Arthroscopic and Related Surgery, 4, pp 215-221, 1988.

Aims

• To estimate the complication rate in arthroscopies of the ankle, knee, hip, wrist, elbow and shoulder.

Methods

• A comprehensive form was completed each month by 21 arthroscopists for a period of 19 months from August 1986 to February 1988.

Results

• 173 complications in 10,282 procedures – a rate of 1.68%, with 95% confidence interval of (1.44% - 1.95%).
  • 8,791 (85.5%) were knee joint; 1,184 (11.51%) were shoulder or subacromial; 146(1.42%) ankle; 79 (0.77%) elbow; 68 (0.66%) were in the wrist; 14 (0.14%) were in the hip.
  • 162 complications in the knee, 9 in the shoulder, 1 in the ankle, and 1 in the hip.
  • The most noted complication was hemarthrosis, with 104 cases reported (>60% of all complications).
  • The second most frequent were infections reported in 21 cases (19 in the knee, 1 in an ankle and 1 in a hip).
  • 7 of the infections were Staphylococcus aureus, 3 were Staphylococcus epidermidis and two were Streptococcus. The average interval between the procedure and the discovery of the infection was 11.7 days.
  • The procedure with the highest complication rate was lateral retinacular release (7%).

Postarthroscopy Surgical Site Infections: Review of Literature, Babcock, HM, Matava, MJ, Fraser, V, Clinical Infectious Diseases, 34, pp 65-71 , 2002.

Results

• Reported complication rate of 14.6% in open procedures. Risks include effusions (12% or procedures), deep vein thrombosis (1.8%-46%), nerve injuries, and arterial injury or aneurysm formation. Infection was the second most common complication.
• Investigators who give a working definition of infection in their reports often rely on culture data.
  • Sherman defines infection as purulent fluid aspirated from the knee from which 1 organism was isolated, reported infection rate of 0.1% (2640 knee procedure)
  • Armstrong reported 18 cases of SSI for 4264 arthroscopic procedures (infection rate of 0.42%). [After study and education, rate dropped to 0.09% during next 2 years.]
  • 3 of 151 patients developed septic arthritis after arthroscopy, then new protocol, 0 infections for next 222 procedures.
• Risk factors for infection: any foreign body (even staples), >50 yrs and tourniquet time >60, use of intraoperative intra-articular steroids (CDC recommends avoiding these steroids).
• In addition, the authors note that more-complicated procedures and longer duration of surgery were also risk factors.

Complications in Arthroscopic Shoulder Surgery, Berjano, P et al., Arthroscopy: The Journal of Arthroscopic and Related Surgery, 14, No 8, pp 785–788, 1998.

• Table of Complications during procedures (15/141 shoulders)
  Pg.787 - Curtis reported 4.6% complication rate arthroscopic procedures
     Table of Complication rate from various authors

Arthroscopy – No Problem Surgery, Sherman, O et al., The Journal of Bone and Joint Surgery, 68-A, No 2, pp 256–265, 1986.

Results

• 8.2% (of 2,640) complications: 126 major (infections, hemarthroses, adhesions, effusions, cardiovascular, neurological, instrument breakage), 97 minor.
• Risk factors:
  • Sex of patient and whether tourniquet had no effect on complication;
  • Experience of surgeon had no correlation with complication rate;
  • Tourniquet used in 44.5% of procedures – 8.9% complication rate (5.4% major);
  • 9.5% of knees had prior surgical procedure – 5.6% complication rate in these knees.
• Model for Major-Complication prediction:
  • Low risk — <30 yrs old and tourniquet time <40 min (predicted 3.2%);
  • Average risk — >30 yrs old and tourniquet time <40 min OR <30 yrs old and tourniquet time between 40 – 59 min (predicted 5.2%);
  • Moderate risk — >30 yrs old and tourniquet time between 40 -59 min (predicted 8.1%);
  • High risk — tourniquet time >60 min (predicted 14.3%).

Incidence and Risk Factors for Surgical Infection after Total Knee Replacement – Babkin et al. Scandinavian Journal of Infectious Diseases. 39.10 (2007): 890-95.

Purpose

• An infected foreign body often requires removal in a second operation, prolonged immobilization and antibiotic treatment and a subsequent third operation. Therefore, preventing infections in operations where foreign bodies are inserted is of paramount importance.

Method

• The operating theatre that was studied was only used for orthopedic operations and was equipped with an air conditioning system without laminar airflow. The system used 100% fresh air pre-filtered by high-efficiency particulate apparatus (HEPA) filter of 95% efficiency enters the room through 6 diffusers located on the ceiling, delivering 3800 m3 per hour. This system has 26 complete air changes per hour.
• The study followed patients receiving total knee replacement and recorded the following information: age, gender, underlying diseases and comorbidities, medications, ASA score, status of the kneed joint, intra-operative factors such as surgeon, surgeons position to patient, surgeon being right or left handed, size and type of prosthesis, duration of surgery, and usage of tourniquet. The post op factors included use of drainage system and volume of drainage, range of motion achieved at discharge from hospital, any infection at discharge, and redness or swelling of surgical site. The follow up period was one year after surgery.
• Superficial SSI involves only skin and subcutaneous tissue; deep SSI involves fascial and muscle layers; and organ/space SSI involves any part of the anatomy other than the incision, opened or manipulated during the operative procedure.

Results

• 180 consecutive total knee arthroplasties (TKR) were studied. Each patient received preoperative antimicrobial prophylaxis, either cefonicid or vancomycin.
• 10 patients developed an infection (5.6%)–3 (1.7%) superficial and 7 (3.9%) organ-space infections.
• The two factors independently associated with SSI first, were left knees were infected 4 times more often than right knees and second, the Johnson & Johnson prosthesis was associated with infection 4 times more often than that of the Biomet prosthesis.
• In addition, if the first surgeon was positioned on the left side of the operated patient, there was an increase in the infection rate. Finally, as the number of surgeons and/or anesthesiologists increased, the rate of wound infection was also higher. However, these factors closely approached but did not reach statistical significance.
• The following variables were not found to be significant risk factors for SSI: the preoperative glucose level and the preoperative erythrocyte sedimentation rate; the preoperative ASA score and NNIS index; the duration of operation; presence of hematomas; and development of a post-operative infection other than a SSI.
• The following items were found to be breaks in adherence to standard infection control recommendations: the OR had 3 doors which allowed frequent entrances and exits of the team, a non-standard horizontal-flow air conditioner was detected that had been installed about the main door, and a washing sink was found on the other side of the main door and had very active use for washing tools before sterilization. After the sink was removed, the air conditioner turned off, and the door locked the SSI rate dropped to 2.2%.

Conclusion

• The surgeon standing on the left side of the patient was statistically significant because the horizontal-flow air conditioner blew bacteria shed from the surgical team onto the patient's wound. The organ space SSI was 1.9% in TKR performed in rooms with conventional air condition compared with 3.9% in rooms with horizontal unidirectional filtered airflow.
• The use of the Johnson & Johnsons prosthesis had a SSI rate of 11% compared to 3% in the Biomet prosthesis. This could be explained in that operation time is about 12 minutes longer in the Johnson & Johnson prosthesis.
• We also found that as the number of orthopedic surgeons or anesthesiologist was higher during an operation, the rate of infections increased as well.
• In the follow up study the use of the Johnson & Johnson prosthesis increased to 75% yet the SSI rate decreased. This could suggest that the Johnsons & Johnsons prosthesis could require a longer learning period.

Risk Factors for Prosthetic Joint Infection: Case-Control Study – Berbari et al. Journal of Clinical Infectious Diseases 27.5 (1998): 1247-254.

Purpose

• Although prosthetic joint infection is rare following the estimated 430,000 total hip arthroplasty (THA) and total knee arthroplasty (TKA) procedures performed in the United States each year, it remains one of the major complications that may lead to prosthesis removal or loss of function and is associated with a mortality rate of 2.7%–18%.
• Prevention of prosthetic joint infection includes augmentation of the host response, optimizing the wound environment, and reduction of bacterial deposition into the wound in the preoperative, intraoperative, and postoperative periods.

Methods

• The study followed patients without a history of prosthetic joint infection who had a THA or TKA at the Mayo Clinic.
• Follow up was twice in the first postsurgical year and then every 5 years thereafter.
• Potential risk factors that were identified are: rheumatoid arthritis, diabetes mellitus, malignancy, join malignancy, steroid use, chronic renal insufficiency, pyuria, bacteriuria, obesity, malnutrition, blood transfusion, Surgery after 12 P.M, surgical site infection, and nosocomial infection.

Results

• This study is based on 462 prosthetic join infections that occurred in 460 of 26,499 patients who received a THA or TKA.
• The median duration between joint arthroplasty and diagnosis of prosthetic joint infection was 512 days.
• Staphylococcus aureus was the most common pathogen followed by a polymicrobial etiology and coagulase-negative staphylococci.
• Antimicrobial prophylaxis administered before surgery was utilized for 392 cases (84.8%) and 402 controls (87%). Cefazolin was the most commonly prescribed surgical prophylaxis followed by methicillin.
• Forty-six (45.1%) of the cases with rheumatoid arthritis and 29 (40.6%) of the controls with rheumatoid arthritis required steroid therapy for management of their disease. Prednisone was the steroid used and the median duration of therapy was 104 weeks.
• The distribution of the American Society for Anesthesia preoperative assessment score [32] was as follows: I—31 cases (7%) and 48 controls (10%); II—219 cases (47%) and 281 controls (61%); III—200 cases (43%) and 120 controls (26%); and IV—9 cases (2%) and 8 controls (2%).
• An additional surgical procedure was performed to treat postoperative wound complications (SSI, wound drainage, wound hematoma, or wound dehiscence) in 29 cases and 1 control.
• Surgical procedures unrelated to postoperative wound complications (such as total joint arthroplasty on a joint other than the index joint), other musculoskeletal surgical procedures, and other surgical procedures were performed for 74 cases and 61 controls.
• Surgical site infections that did not involve the joint prosthesis developed during the index hospitalization a median of 13 days and 12.5 days after the time of index arthroplasty for the cases and controls, respectively.

Conclusion

• This study defined four independent risk factors for prosthetic joint infection the development of a surgical site infection not involving the prosthesis, an NNIS System surgical patient risk index score of ≥ 1, a history of malignancy, or a history of prior total joint arthroplasty.
• An increased risk of prosthetic join infection in patients with rheumatoid arthritis was observed. This risk following THA and TKA was 1.8 and 2.8 fold times higher respectively in patients with RA than in patients with degenerative joint disease.

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