Orthopaedic Surgery Specialties
Hand surgery infection rates are generally low, and multiple studies have shown an infection rate of less than 1%.[13,14] Some factors associated with SSIs in hand surgery include diabetes, immunosuppression, severe burns, malnutrition, open fractures, animal or human bites, and severely crushed or contaminated wounds.[15–17] Staphylococcus aureus is the organism most commonly associated with postoperative infection. There is no general agreement on which skin antiseptic is the best to minimize SSIs in hand surgery.
Although there is a shortage of studies looking at the association between skin preparation solution used and SSIs in hand surgery, the results of a 2016 study comparing the efficacy of surgical preparation solutions in clean elective hand surgery by analyzing post-preparation bacterial cultures found that DuraPrep (iodine povacrylex and isopropyl alcohol) and Betadine (povidone-iodine) were markedly better than ChloraPrep (chlorhexidine gluconate and isopropyl alcohol) for skin decontamination. However, no SSIs were noted within 30 days of surgery in any of the 119 patients studied.
Another 2016 study from researchers in Iran showed that non-rinse alcoholic hand disinfectants had superior immediate effects on disinfecting bacterial colonies than 7.5% povidone-iodine, but ultimately no notable difference exists in colony-forming units between the two groups after 2 hours. The authors suggested that alcohol-based solutions may be preferable to povidone-iodine solution in emergency situations.
Seigerman et al reported on two methods of applying antiseptic solutions to the skin of the hand and found that two fellowship-trained orthopaedic hand surgeons left markedly less areas of the skin unprepared when using 4 × 4 inch sterile gauze sponges relative to when they used commercially available prep-stick applicators.
Because of the low infection rates in hand, there is no consensus on what prep solution is best used. However, we can infer from the studies that using 4 × 4s to prep the skin with one of the prep solutions has the unique advantage of reaching crevices and other hard to reach areas in the hand that large applicators otherwise have a difficult time adequately sterilizing. Despite iodine-based solutions having a better skin decontamination rate in one study, no study could find a difference in SSIs between any of the preps. This brings to light the fact that although some preps may be better at decreasing bacterial loads on the skin, clinically there may be no advantage in using them over a more inexpensive or easily accessible prep solution. The main conclusion drawn for hand surgery is that 4 × 4 inch sterile gauze sponges used with any of the three main prep solutions may have a better ability to get into the crevices of the hand because of the more complicated nature of prepping the hand (Table 2).
SSIs after joint arthroplasty can be potentially devastating, and the morbidity associated with them can be enormous. Thus, preventing SSIs in joint arthroplasty is of utmost importance. Rasouli et al reported an SSI rate of 1.31% in 6,111 total joint arthroplasties analyzed, with the highest rates occurring in revision total knee arthroplasty (4.57%), followed by revision hip arthroplasty (1.94%). Risk factors for infection include higher Charlson Comorbidity Index, revision total knee arthroplasty, and a low preoperative hemoglobin level. The most commonly detected microbes causing joint infection are staphylococci, including S aureus and coagulase-negative staphylococci.
Preoperative skin preparation in joint arthroplasty surgeries is a necessary method to reduce SSI incidence. Although the general surgery literature does report a lower rate of superficial SSI with chlorhexidine-alcohol within 30 days of surgery compared with povidone-iodine, research on the association between different kinds of SASs and complications in joint arthroplasty cases is relatively lacking. However, a few studies do compare the efficacy of different iodine solutions.
One study compared iodophor-in-alcohol solution with an aqueous iodophor solution scrub and found no notable difference in SSI rates between the two. Another study compared the combination of iodine povacrylex and isopropyl alcohol with a povidone-iodine–impregnated skin preparation tray. This study also found that the two groups had similar bacterial contamination rates. Both studies showed superior drape adherence to skin with the iodine alcohol solution relative to its aqueous counterpart.
Finally, a 2016 prospective study analyzed whether the application of an additional surgical site preparation solution with iodine povacrylex and isopropyl alcohol before application of the final adhesive drape would result in lower SSI rates in patients undergoing total hip and total knee arthroplasty. The study found a notable reduction in the incidence of superficial SSIs in the intervention group compared with the control group that only received a single surgical site preparation solution with alcohol and povidone-iodine before draping. This study brings up an important point of second skin prep. Often the process of draping may contaminate either those draping the patient or the surgical site. A second prep right after draping can help ensure that the surgical site is adequately sterilized. This does not mean that if the surgical site is contaminated during draping, a second prep would suffice. In fact, if contamination is noted during draping, everything should be taken down and re-prepped. But in cases where surgical infection is more likely or of greater morbidity, such as in total joint surgery, a second prep is a prudent and well-advised step.
The literature on joint surgery has multiple more recommendations with regard to draping and preoperative shaving, which is beyond the scope of this article. But the conclusions we can draw in joint surgery are that (1) an additional surgical site preparation before the final drape is beneficial in reducing SSIs and (2) although iodine-based solutions have been shown to have consistent and similar bactericidal effects, drapes adhere better to skin with iodine alcohol solution. So if using drapes with self-adhesive, iodine alcohol solution may be best to provide a more robust barrier.
Foot and Ankle Surgery
Foot and ankle surgery has been associated with higher infection rates than many of the other subspecialties of orthopaedics, with infection rates as high as 6.5% being reported. Risk factors for SSIs in foot and ankle surgery include diabetes, peripheral neuropathy, Charcot neuroarthropathy, current or past smoking, and increased length of surgery. Some potential explanations suggested for these elevated rates of infection in foot and ankle surgery include the resident microbiota of this region of the body and the wearing of shoes which may facilitate a favorable environment for bacteria to grow. S aureus was found to be the main microbe at fault for wound infection in one study on foot and ankle surgery infection rates.
Surgical preparation solutions have been shown to be an effective way of eliminating bacteria from feet. A 2005 study of 125 patients undergoing surgery of the foot and ankle compared the efficacy of DuraPrep (0.7% iodine and 74% isopropyl alcohol), Techni-Care (3.0% chloroxylenol), and ChloraPrep (2% chlorhexidine gluconate and 70% isopropyl alcohol). The authors found ChloraPrep to be the most effective prep solution for eliminating bacteria from the forefoot before surgery.
A 2013 meta-analysis of different surgical site skin preparation methods (alcoholic chlorhexidine, alcoholic povidone-iodine, a two-step intervention using povidone-iodine scrub and paint followed by alcohol, and a two-step intervention using chlorhexidine scrub followed by alcohol) concluded that no method was definitively superior to the others. This analysis compared preoperative washing with antiseptic agents and intraoperative sterile brush scrubbing of the foot and ankle area. More recently, a 2016 study showed that bacterial counts did not markedly differ between patients who had their foot and ankle immersed in a nonsterile bag filled with 60 mL of 2% chlorhexidine with 70% alcohol and patients who had the traditional preoperative surgical site skin preparation of the same solution painted onto the foot and ankle with standard gauze.
A randomized, prospective study looked at skin preparation before foot and ankle surgery using one of two preparation routines. One group, called isopropyl alcohol group, was prepped with a 4% chlorhexidine application, followed by an alcohol rinse. The other group, chlorhexidine gluconate group, was prepped with alcohol, followed by chlorhexidine. The study found no notable difference in the level of postoperative culture swab growth and no difference in SSIs between each group. These studies looked at different prep solutions on different parts of the foot. Although no study found a notable difference in post-SSIs between any of the preps, ChloraPrep was found to markedly reduce bacteria in the forefoot in one study. Based on these studies, we conclude that the combination of chlorhexidine and alcohol should be used when disinfecting the skin of the foot before surgery. Although this is our recommendation, it is worth mentioning that all preps in the foot have been shown to be equivalent with regard to preventing SSIs.
The incidence of infection in arthroscopic surgery is likely the lowest among all orthopaedic subspecialties. Infection rates after knee arthroscopy range from 0.04% to 0.42%.[9,10,12,23,27,33] An article published in June 2017 found a number of variables associated with postoperative infection, including younger age, morbid obesity, tobacco use, inflammatory arthritis, chronic kidney disease, hemodialysis, depression, and a hypercoagulable disorder.
Because of the minimally invasive nature of arthroscopy, not much information is available about skin preparation practices in joint arthroscopic surgery. Shoulder arthroscopy is no exception. Cutibacterium acnes, which is a major causative agent of SSIs in spinal surgery as well, has been associated with pain and stiffness after shoulder arthroscopy. This bacterium has been found more commonly in patients who are male, have preexisting shoulder arthroplasty prosthesis, and revision, as well as in patients with a greater density of hair follicles and sebum. Even with the use of a 4% chlorhexidine scrub, followed by a 2% chlorhexidine gluconate and 70% isopropyl alcohol paint applied to the entire shoulder preoperatively, C acnes has been found in deep tissue of patients undergoing shoulder arthroplasty at a rate of 19.6%. Because C acnes causes poor outcomes postoperatively, measures have been taken to decrease C acnes skin colonization preoperatively.
A 2017 study analyzed bacterial cultures taken from patients undergoing shoulder arthroscopy before and after surgery. The study concluded that applying topical benzoyl peroxide 5% and clindamycin 1% gel at night within the 10 days before surgery is effective in reducing both superficial and deep C acnes in shoulder arthroscopy. It found that shoulder joint inoculation with C acnes decreased from 19.6% to 3.1% in 65 patients enrolled. Another 2015 study found that treating patients with benzoyl peroxide cream 48 hours before surgery in conjunction with standard chlorhexidine skin preparation reduced C acnes before and after surgery, which may result in lower postoperative infection rates.
The effectiveness of DuraPrep (iodine povacrylex and isopropyl alcohol), ChloraPrep (chlorhexidine and isopropyl alcohol), and Betadine (povidone-iodine) in eradicating bacteria in shoulder surgery (137 of 150 procedures were shoulder arthroscopies) was studied by Saltzman et al. They found an overall positive culture rate after skin preparation being highest in the povidone-iodine and paint group (0.75% iodine scrub and then 1.0% iodine paint), followed by DuraPrep. ChloraPrep had the lowest positive bacterial cultures. However, no infections occurred in any of the 150 patients undergoing shoulder surgery in this study at a minimum of 10-month follow-up.
Although the above-mentioned studies confirm that benzoyl peroxide cream administered before surgery decreases inoculation with C acnes, there has been no proof that this leads to a decreased level of infections. This lack of statistical difference is likely because of the very low rate of infection inherent in arthroscopy. To detect one infection, a much larger population would be needed. Thus, we recommend benzoyl peroxide cream before surgery along with a chlorhexidine skin prep solution to lower the risk of infection.
No studies could be found comparing the efficacy of different skin preparation solutions in knee arthroscopy. Despite the lack of variability in SASs in arthroscopy, a 2006 study found that presurgical disinfection of the patient's skin with povidone-iodine was shown to be completely effective, with 100% of 30 samples taken from patients' knees perioperatively being negative for bacterial infection. Another study comparing preoperative preparation of the knee with povidone-iodine scrub with a two-stage preparation of preoperative iodine scrub, followed by painting with aqueous povidone-iodine, found no notable difference in SSIs between 300 patients in the two groups (no SSIs in either group). Based on the above-mentioned studies and lack of sufficient evidence, we do not have a formal recommendation, though povidone-iodine is an adequate and proven skin prep for knee arthroscopy.
Just as in patients undergoing knee arthroscopy, iodine solutions such as DuraPrep (iodine povacrylex) are used to prepare the skin in patients undergoing hip arthroscopy. In a large systematic review by Harris et al, infection rate of less than 1% was found in hip arthroscopy cases. Infection in patients after hip arthroscopy has been associated with intra-articular hip injection in 3 months before the procedure. No research compares the efficacy of different SASs in preventing infection after hip arthroscopy.
Spine surgery carries a high risk for postoperative infection. A possible explanation for this large SSI range is that many variations exist in surgical factors such as implant usage and surgical approach. SSIs in spine surgery are associated with obesity, diabetes, cigarette smoking, obesity, steroid use, alcohol abuse, extremes of ages, and transfusion of blood products.[42,43] S aureus was the most commonly isolated pathogen in spinal SSIs; however, gram-negative organisms accounted for a considerable number of SSIs among lower lumber and sacral spinal procedures in one study.
A 2012 study comparing the efficacy of an iodine-alcohol solution (DuraPrep) against a chlorhexidine gluconate-alcohol solution (ChloraPrep) in eliminating bacterial flora overlying the lumbar spine found that the two are equally successful antiseptic agents. Variations exist also in timing and techniques for skin preparation before spine surgery, which have been investigated for their efficacy in eliminating bacteria. One of the most commonly used skin antiseptic agents is povidone-iodine. Yasuda et al conducted a study comparing bacterial cultures in two groups: group A which received povidone-iodine directly before skin incision, after the surgeon's hands were scrubbed, and group B which had povidone-iodine applied at least 5 minutes before skin incision, before the surgeon's hands were scrubbed. In the latter group, povidone-iodine had enough time to dry, leading to markedly lower positive culture rates than in the former group.
Thus, we conclude that ChloraPrep or DuraPrep used as the surgical preparation solution are both equally effective. The study by Yasuda highlights the importance of letting the prep solution dry for it to exert its effects on the skin. For spine surgery, we recommend that the prep be allowed to dry before incision. This recommendation can be carried to all surgical prep applications.
Orthopaedic oncology surgery cases can necessitate a large incision and long surgical time, both of which predispose a patient to SSIs. Thus, these patients are at higher risk for infection and necessitate a careful skin preparation routine. An analysis of 1,521 orthopaedic oncologic surgical procedures in 1,304 patients in 2014 showed a 10.1% SSI rate. This 2014 study identified eight patient-related variables associated with SSIs in orthopaedic oncology surgery: body mass index, age, number of preexisting implants or allografts, infection at another site on the date of surgery, malignant disease, and hip region infected. The study also had access to information pertaining to the preparation solution used. A comparison between "triple" (soap, povidone-iodine [Betadine], and alcohol), DuraPrep, and "other" (representing any other SAS) showed no notable difference in SSI rates.
Because orthopaedic oncology cases vary greatly and can range anywhere from large pelvic reconstructions to arthroscopy cases, we recommend that preps for oncology cases follow the specific area of the body previously discussed, so that large knee reconstructions should follow skin prep guidelines for arthroplasty, whereas tumor excisions in the hand and upper extremity would be suited by following guidelines under hand procedures.
J Am Acad Orthop Surg. 2019;27(16):599-606. © 2019 American Academy of Orthopaedic Surgeons