The management of malignant bone tumors requires multidisciplinary interventions including chemotherapy, radiation therapy, and surgical tumor resection and reconstruction. Surgical site infection (SSI) is a serious complication in the treatment of malignant bone tumors. Compared to other orthopedic surgeries, the surgical treatment of malignant bone tumors is associated with higher rates of SSIs. In patients with SSIs, additional surgeries, long-term administrations of antibiotics, extended hospital stays, and the postponement of scheduled adjuvant treatments are required. Therefore, SSI may adversely affect functional and oncological outcomes. To improve surgical outcomes in patients with malignant bone tumors, preoperative risk assessments for SSIs, new preventive techniques against SSIs, and the optimal use of prophylactic antibiotics are often required. Previous reports have demonstrated that age, tumor site (pelvis and tibia), extended operative time, implant use, body mass index, leukocytopenia, and reconstruction procedures are associated with an increased risk for SSIs. Furthermore, prophylactic techniques, such as silver and iodine coatings on implants, have been developed and proven to be efficacious and safe in clinical studies.
1. Introduction
The treatment of malignant bone tumors requires multidisciplinary interventions such as surgical tumor resection, chemotherapy, and radiation therapy. After surgical tumor resection, most bone defects require reconstruction using endoprostheses, allografts, autografts, artificial bones, or distraction osteogenesis
[1,2,3,4,5][1][2][3][4][5]. During the surgical treatment of malignant bone tumors, risk conditions such as soft-tissue defects, large implants, allografts, frozen or irradiated bone, and radiation-therapy- or chemotherapy-induced immunodeficiency may cause complications (including surgical site infection (SSI), the loosening and breakage of the implant, delayed union, and the fracture of the grafted bone). SSI is one of the most severe complications related to bone tumor surgeries. The incidence of SSI following malignant bone tumor surgery has been reported to be 3–10 times higher than that following general orthopedic surgery
[6,7][6][7]. The incidence of SSI in patients who underwent orthopedic surgeries was reported as 0.2–4.2%
[8,9,10,11,12,13][8][9][10][11][12][13]. The incidence of SSI in total hip arthroplasty was reported as 0.2%
[13], whereas the incidences of SSI in spine surgeries were reported as 3.4–4.2%
[10,12][10][12]. On the other hand, high incidences of SSI have been reported in patients with malignant bone tumors
[14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. In patients who underwent megaprosthesis after malignant bone tumor resection, 9.3–20.4% of the patients had SSI
[14,15][14][15]. SSI rates after biological reconstruction were reported as 11.9–13.5%
[16,17][16][17]. In patients with SSI, additional treatments (such as the long-term administration of antibiotics, implant and grafted bone removal, debridement, irrigation, and reconstruction) are often required. Therefore, SSIs entail longer periods of hospitalization, functional deteriorations, excessive medical costs, and delays in the treatment course, which increase mortality
[30,31,32][30][31][32].
During bone cancer surgery, surgical reconstruction of the bone, ligaments, tendons, nerves, and vessels requires a long operative time and biomaterials, which may increase the risk of SSIs. Therefore, a preoperative assessment of the risk of complications is needed, and appropriate surgical procedures and adjuvant treatments should be chosen based on the risks and benefits of the surgery. In addition to the rarity of malignant bone tumors, the diversity of tumor locations, surgical procedures, biomaterials, and neoadjuvant or adjuvant treatments makes it difficult to identify risk factors for SSI. However, several studies have demonstrated predictive factors for SSI in patients with bone tumors. Furthermore, new techniques of antibacterial coating on implants have been developed, and their usefulness has been reported.
2. Current Practices in the Prophylaxis of SSI and Emerging Techniques
Although perioperative intravenous antibiotics are commonly administered to prevent SSI, there are still controversies regarding antibiotic regimens that can effectively prevent SSI. At the International Consensus Meeting on Musculoskeletal Infection, there was no recommendation to adjust the type, dose, and duration of antibiotic prophylaxis in patients undergoing oncologic endoprosthetic reconstruction from that which is routinely administered in conventional total joint arthroplasty
[64][33]. A meta-analysis showed that the rate of SSI after endoprosthetic reconstruction in the lower extremity was 10%, and that the postoperative use of prophylactic antibiotics for a period longer than 24 h decreased the risk of SSI
[65][34]. Contrarily, Ghert et al. conducted the Prophylactic Antibiotic Regimens in Tumor Surgery (PARITY) trial to compare the effects of a 5-day postoperative intravenous antibiotics regimen with those of a 1-day regimen on the prevention of SSI and antibiotics-related adverse effects in patients who underwent tumor resection and endoprosthetic reconstruction of the lower extremity
[66][35]. In this
res
tudyearch, 604 patients were randomly allocated to either the 5-day regimen or the 1-day regimen group. The incidences of SSI in patients treated with the 5-day regimen and 1-day regimens were 15% and 17%, respectively (hazard ratio (HR) = 0.93,
p = 0.73). The incidences of antibiotics-related adverse events in the 5-day regimen group and 1-day regimen group were 5% and 2%, respectively (HR = 3.24,
p = 0.02). Although the randomized trial showed no significant benefits of a longer period of antibiotic administration, the duration of antibiotic use should be determined based on the risk of SSI in each case.
Bacteria generate biofilms on the surfaces of implants, and antibiotics cannot reach the bacteria through the biofilms. Most cases of infection around implants require the removal of the implants. Implant-related infections were significantly associated with amputation (OR = 24.0,
p < 0.001) and worse functional outcomes (OR = 0.01,
p < 0.001), and the success rate of infection treatment without the removal of the implant was only 4.5%
[31]. Therefore, the prevention of infection on implant surfaces is required to reduce the risk of SSI in patients who undergo surgical treatment using implants. Recently, antibacterial coating techniques (such as silver coating, iodine coating, and antibiotics coating) have been developed (
Table 31)
[67[36][37][38][39],
68,69,70], and some basic and clinical studies have proven the safety and efficacy of these various coating techniques
[71][40]. These techniques are thought to reduce the social and economic burden of implant-related infections in orthopedic surgeries.
The antibacterial activity of silver mostly depends on its ability to interfere with bacterial cell membrane permeability and cellular metabolism
[71][40]. Silver coatings have been used on tumor prostheses
[72,73][41][42]. Fiore et al. conducted a meta-analysis on SSI in patients treated with silver-coated megaprostheses
[74][43]. In this
rees
tudyarch, the patients with the silver-coated megaprostheses had an infection rate of 9.2% after primary surgery, whereas the patients with uncoated megaprostheses had an infection rate of 11.2%. In contrast, the infection rate after revision megaprosthesis was 13.7% in patients with silver-coated megaprostheses and 29.2% in patients with uncoated megaprostheses (
p = 0.019). This
studyreearch suggests that the silver-coated megaprosthesis is effective in reducing the incidence of SSI in patients at a high risk of postoperative infection. In a retrospective study involving 51 patients with bone sarcoma who underwent megaprosthesis replacement, the infection rates in patients with silver-coated megaprostheses and control patients were found to be 6% and 18%, respectively (
p = 0.062)
[70][39]. In another retrospective case-control study, the clinical outcomes of silver-coated tumor prostheses in 85 patients were compared with 85 matched controls
[67][36]. The infection rates in the silver-coating and control groups were 12% and 22%, respectively (
p = 0.033). After debridement, antibiotics administration, and implant retention in patients with SSI, the success (infection control) rates in patients with silver-coated implants and control patients were 70% and 32%, respectively (
p = 0.048). Parry et al. compared the clinical outcomes of silver-coated endoprostheses in 89 patients at high risk for SSI with the outcomes of non-silver-coated endoprostheses in 305 patients
[75][44]. Although the silver-coated prosthesis group had a higher risk of SSI, no significant difference in infection rates was reported between the silver-coated endoprosthesis (12%) and uncoated endoprosthesis (8%) groups (
p = 0.154). Although silver-coating seems to be effective in the prevention of SSI, it has some disadvantages, such as the cytotoxicity of silver ions to bone cells, the incomplete protection of the implant, and the high cost of the technique
[76,77][45][46].
Povidone-iodine can be used as an electrolyte to form an adhesive porous anodic oxide (which retains the antibacterial properties of iodine)
[78][47]. In basic research, an iodine coating showed a good antibiofilm effect, a long antibacterial effect, good osteoconductivity, and safety to human cells
[78][47]. In clinical studies, iodine-coated titanium showed a preventive effect against SSI
[68,69,78][37][38][47]. Tsuchiya et al. investigated the effect of iodine-coated implants in 222 patients with immune-compromised conditions or postoperative infection
[69][38]. Iodine-coated implants were used to prevent infection in 158 patients and treat active infections in 64 patients. Among patients in whom iodine-coated implants were used to prevent infection, 1.9% developed acute infection. All patients with active infection could be treated successfully without implant removal. In their study, no cytotoxicity or adverse effects were observed. Shirai et al. investigated the effect of iodine-coated implants on the infection rates in patients who underwent tumor resection and reconstruction using tumor-bearing frozen autografts
[79][48]. They reported that 10 of 62 (16%) patients treated with uncoated implants had deep infections, whereas only 1 of 38 (3%) patients treated with iodine-coated implants had a deep infection (
p = 0.032). In another study investigating the predictive factors for SSI in patients who underwent malignant bone tumor resection and reconstruction, iodine-coated implants significantly reduced the risk of SSI (OR = 0.3)
[26].
Although there are limited reports on the effectiveness of antibiotics-coated implants in patients with bone tumors, several reports exist on the effectiveness of these implants in the treatment of fractures
[80,81][49][50]. Fuchs et al. reported that no implant-related infections were observed in 21 patients treated with gentamicin poly (D, L-lactide)-coated intramedullary nails for closed or open tibial fractures, except for one patient who had wound-healing difficulties
[80][49]. Metsemakers et al. investigated clinical outcomes of gentamicin-coated intramedullary nails in 16 patients with open tibial fractures, including 11 acute fractures and 5 revision cases
[81][50]. In their study, no patient had a deep infection after surgery using gentamicin-coated nails. However, four (25%) patients had nonunion. In a multicenter prospective study involving 99 patients with fresh tibial fractures or who underwent revision surgeries for nonunion, deep infection or osteomyelitis was observed in 7.2% of patients with fresh fractures and 8% of patients who underwent revision surgeries
[82][51]. However, this technique has some disadvantages: its availability is limited only to patients with tibial defects, and its effect is reduced in the event of gentamicin resistance
[71][40].
Table 31.
Antibacterial coating techniques for the prevention of SSI during bone tumor surgery.