The incidence of infection after internal fixation of tibial plateau fractures is higher than other parts significantly. Researchs found that open fractures, operation time and smoking are high risk factors for infection [13, 14]. However, there is still no consensus on the treatment of infection after internal fixation of tibial plateau fractures, especially the preservation of internal fixation. Clinicians have different opinions on this issue. Parkkinen et al. believed that the internal fixation should be removed first. Thorough debridement, repeated lavage, systemic or local antibiotics, and flap coverage should be used for treatment according to the patient's condition [15, 16]. Patzakis et al. believed that the stability of the broken end should be considered first, and advocated that the internal fixation should only be removed when the fracture has healed or the internal fixation failed . In our opinion, whether to retain internal fixation should take into account the occurrence time of postoperative infection, the degree and scope of infection, the stability and healing of fracture end, the therapeutic effect of antibiotics, the patient's physical condition and the patient's own will. In the case of retaining internal fixation, if the stability of the fracture end can be maintained, infection was controlled until the fracture healing, which is beneficial to the preservation of knee function. If the infection is severe, the internal fixation failed after debridement, and the broken end is unstable, external fixation should be performed in time. Functional exercise should be carried out as soon as possible after infection control and fracture healing . In our study, the criteria of retaining internal fixation: ⑴Thorough debridement can be performed at the site of infection. ⑵Internal fixation does not fail after debridement. ⑶Bone plate and bone surface fit closely. In such cases, internal fixation can provide more effective fixation of the fracture end. ⑷Local soft tissue condition is good. ⑸The patient is at an early stage of infection. ⑹The fracture has not healed. The criteria of removing internal fixation: ⑴In the case of internal fixation, thorough debridement cannot be performed. ⑵Internal fixation fails after debridement. ⑶The patient is in the stage of delayed infection, and the fracture has healed or partially healed. ⑷The infection is severe and extensive.
The first issue is to control the infection for the treatment of infection after internal fixation of tibial plateau fractures. The research found that early infection after internal fixation of tibial plateau fractures was mostly surgical incision infections . Thorough debridement, adequate drainage and the application of antibiotics can make infection control rate reached 71% while retaining internal fixation . Internal fixation as a metal foreign body, bacteria can form a biofilm on its surface. The resulting barrier effect and low metabolic state of bacteria will make bacteria hard to be killed by antibiotics . However, for the early infection after internal fixation of tibial plateau fracture, the fracture has not yet healed, and the stability provided by internal fixation is also very important for infection control. Therefore, we tried to retain the internal fixation for patients who meet the retention criteria, and then tried to reduce the degree and scope of infection through thorough debridement and application of antibiotics. Even if the infection cannot be eliminated completely, this method also can ensure the infection will not develop further. We tried to make the fracture heals in the case of infection and turn the fracture combined with infection into separate infection. The difficulty of follow-up treatment will be reduced greatly . In this study, the internal fixation of 18 patients were tried to be preserved. Except for 1 patient with recurrence of infection, the other 17 patients controlled the infection successfully until the fracture healed. The internal fixation of 14 patients was removed completely in the first-stage operation due to severe infection, and the postoperative infection was controlled. Late infection will affect the healing of the fracture and cause infectious nonunion. In order to control infection better, the internal fixation is often chosen to be removed. If the fracture is still in the process of healing, internal fixation is effective after thorough debridement and antibiotic therapy is effective, which can still be selected to control the infection until the fracture healing under circumstance of retaining internal fixation. However, it is necessary to pay close attention to the patient's condition during this process . Once the infection is not controlled effectively or even shows signs of recurrence, it is necessary to remove the internal fixation immediately and take appropriate measures to control the infection. In this study, due to the wide range of infection and poor healing of the broken end, the internal fixation of 14 patients with late infection was removed completely on the basis of thorough debridement, antibiotic artificial bone was implanted and external fixation was used for fixation.
The application of antibiotics has always played a very important role in the treatment of bone infection. Shen applied antibiotic bone cement to control the local infection after thorough debridement, and then performed bone grafting to restore the local bone defect after 6 ~ 8 weeks . The infection control rate reached 90%, but the infection recurrence rate after the first stage of this method was higher, multiple debridements are required. Furthermore, antibiotic bone cement cannot be degraded in the body and require second operation to remove . In order to solve this problem, calcium sulfate is used widely in clinical practice as a new type of antibiotic loading material. The substance can be degraded completely in the human body, and loaded antibiotics can be released within 6 ~ 8 weeks to maintain effective local bactericidal concentration of the lesion. Jiang et al. reported that using vancomycin calcium sulfate to treat chronic osteomyelitis of calcaneus . Although the infection was controlled, the incidence of aseptic wound exudation reached 32%. Ruan et al. reported that anti-infection treating after internal fixation of tibial plateau fractures using antibiotic-impregnated calcium sulfate led to aseptic wound exudation incidence reduce to 3% . He believed that persistent wound exudation was related to the massive implantation of calcium sulfate. The researchers found that the release rate of antibiotics loaded with calcium sulfate in the body is relatively stable and wouldn’t represent explosive release similar to bone cement. However, the support strength provided by this substance is insufficient and the osteoinductive ability is weak. The degradation process will produce a lot of water, which may aggravate local infection and limit its clinical application range . Therefore, in this study, the antibiotic sustained release system is a mixture of calcium phosphate with good biocompatibility and antibiotics such as vancomycin. Previous researches indicated calcium phosphate can achieve efficient adsorption of drugs through hydrogen bonding and electrostatic attraction, which can reduce the explosive release effectively at the initial stage after implantation. The local drug concentration can reach more than 4 times of the systemic administration and the effective antibacterial concentration can be maintained locally for 6 ~ 8 weeks [26,27,28]. Calcium phosphate can also promote activities of osteoblast differentiation and angiogenesis. With the development of bone immunology, calcium phosphate has also been found to have significant immunomodulatory function. Wang et al. discovered that calcium phosphate and its degradation products can promote macrophages to secrete inflammatory cytokines and growth factors, which play a positive role in the migration and osteogenic differentiation of mesenchymal stem cells . Therefore, the use of calcium phosphate loaded with antibiotics to treat infection after internal fixation of tibial plateau fractures can not only plug the dead space and release sensitive antibiotics slowly to control infection, but also induce the repair of bone defects and promote bone healing. In this study, all 32 patients were implanted with antibiotic artificial bone during the first-stage operation, and 31 patients controlled the infection successfully. Due to poor infection control, antibiotic artificial bone was implanted again in one patient, and postoperative infection was controlled effectively. After implanting calcium phosphate loaded with antibiotics, the infection was controlled and the fracture healed well in 20 patients without secondary bone grafting, which accelerated the recovery of patients greatly and helped preserving the function of the affected limb.
In the process of applying antibiotic artificial bone to treat infection after internal fixation of tibial plateau fractures, the use of internal fixation and external fixation should be selected flexibly according to the actual situation of the patient under the guidance of the principles of controlling infection, promoting fracture healing, and maintaining joint function. In the process of treatment, we believe that the following points should be noted: ⑴Debridement is very important. In this process, sequestrum and infected tissues should be removed completely to provide a suitable microenvironment for infection control and bone repair. ⑵The implantation of calcium phosphate should be filled fully without leaving gaps, especially around the internal fixation. ⑶The stability of the fracture end is important for infection control and fracture healing. If the internal fixation failed, external fixation should be employed in time. ⑷Due to the special anatomy of the tibial plateau, soft tissues should be protected as much as possible during the operation. If the wound cannot be closed directly, skin flaps should be used in time. ⑸Functional exercise should be performed as soon as possible after the operation, which can preserve the joint function of the patient to the greatest extent.
This study is limited in its small case number, retrospective study design and lack of control group, which may reduce the persuasiveness of research conclusions. It is necessary to introduce a larger sample of randomized controlled trials to enhance the conviction of the conclusions.