With the rapid development of spinal surgery, new equipment, new products, new techniques and even new approaches have emerged and greatly promoted the development of spinal surgery; new techniques such as minimally invasive spinal surgery have been developed and have achieved good clinical results; however, the potential complications associated with various techniques and products have brought a burden to patients and new thoughts to surgeons, of which deep incisional infection is a spinal A serious postoperative complication in surgery.
With the prevalence of minimally invasive spine surgery techniques and the increasing proportion of internal fixation implants in spine surgery, the occurrence of deep postoperative incisional infection and its impact on surgical outcomes is a growing concern.
It is true that due to improved diagnostic techniques, antibiotic treatment, advances in surgical techniques, and enhanced postoperative care, the rate of death and disability due to infectious complications has decreased significantly, but there are still difficulties in early diagnosis and treatment, and early diagnosis and appropriate treatment are essential to reduce the rate of disability. This paper briefly describes the problems and prevention strategies related to postoperative infection in spine surgery as follows.
I. Classification of deep postoperative incisional infections in spine surgery
The timing of early and late infections is inconclusive. Wimmer (1996) referred to infections occurring within 20 weeks after surgery as early infections and those occurring after 20 weeks as late infections; Rechtine (2000) referred to infections occurring within 3 weeks after surgery as acute infections and those occurring 4 weeks after surgery as chronic infections;
Equuschus et al. (2001) defined infections occurring after 3 months as late onset infections; Sampedro (2010) called infections occurring within 30 d after surgery as early onset infections and those occurring after 30 d as late onset infections; comprehensive domestic and international literature reported that, according to the time of infection onset, infections occurring within two weeks after surgery were diagnosed as acute infections and those occurring more than two weeks were diagnosed as late onset infections (mostly).
Comparison of the rate of deep incisional infection after different types of spinal internal fixation
A review of the relevant literature shows that the factors affecting deep incisional infection are multiple and are summarized as follows: posterior surgery > anterior surgery; deep infection > superficial infection; surgery with endografts > surgery without endografts; invasive operations (discography, chemical nucleolysis, myelography, epidural injection) > single surgery; patients with underlying diseases (diabetes mellitus, etc.) > patients without related underlying diseases; patients older than 55 years old > patients younger than 55 years old; and patients with lumbar spine. Patients younger than 55 years old; lumbar and thoracic spine surgery > cervical spine surgery; thoracic spine surgery > lumbar spine surgery; blood transfusion and long operation time > no blood transfusion and short operation time.
Third, the risk factors and causes of surgical site infection
The risk factors leading to SSI (surgical site infection, SSI ) are divided into 3 main categories.
① Factors related to the nature of the spinal lesion and the surgical procedure;
(ii) Factors related to the patient’s general health status;
(3) Others: advanced age (especially >70 years), obesity, diabetes, chronic obstructive pulmonary disease, coronary artery disease, osteoporosis, malnutrition, long-term hemodialysis patients, history of spinal surgery at the same site, history of SSI, perioperative transfusion of allogeneic blood, excessive intraoperative blood loss (especially >1 L), excessive intraoperative operating room staff (>10), prolonged operative time (>5 h), prolonged preoperative hospitalization (>7 days) The duration of preoperative hospitalization was too long (>7 days).
The main causes of infection at different times after spinal surgery
The causes of early postoperative infection include: irregular intraoperative aseptic operation, excessive use of electric knife, poor postoperative drainage, prolonged retention of drains, and retrograde infection; in addition, poor paravertebral soft tissue conditions and decreased resistance to infection are also causes of infection. Other causes such as age, poor physical resistance, surgical site, and surgical exposure time are all causes of infection.
The causes of delayed infection are more complex, and most scholars believe that it may be related to the following factors:
(1) High surgical trauma, excessive soft tissue stripping resulting in large trauma and bleeding, as well as excessive use of electric knife causing ischemic necrosis of muscle soft tissue;
(ii) Long operation time, inadequate postoperative drainage, and dead cavity left when the incision was sutured;
③ not strictly aseptic operation;
④Loose internal fixation may also be the cause of delayed infection;
⑤ Patients with low immunity, long-term use of hormones or immunosuppressants, etc.
According to the literature, the factors affecting deep incision infection after internal spinal fixation include age, preoperative general condition, duration of surgery, intraoperative blood loss and postoperative blood transfusion, and surgical site, which can increase the risk of deep incision infection after internal fixation.
V. Indicators of early and late infection
The diagnosis of early-onset infection after spinal fusion is difficult; especially after the clinical use of antibiotics, the diagnosis relies on specific signs of infection and relevant evidence from laboratory and imaging. Infections after posterior spinal internal fixation are mostly paravertebral soft tissue infections. Early onset: The possibility of early infection should be highly suspected once the patient develops increased body temperature, increased incisional pain, and significantly higher WBC, ESR, and CRP after spine surgery;
Late infection: after spinal surgery, the patient after a period of normal recovery appears pain or increased pain in the affected area, or there is an increase in ESR; however, the role of X-ray diagnosis is not very clear, bacterial culture can be used as a basis for determining the diagnosis and the choice of medication, the length of bacterial culture has an important impact on the results.
VI. The significance of commonly used related indicators
WBC: WBC has a slightly lower sensitivity and is a relatively unreliable indicator for the diagnosis of infection. In patients suspected of having postoperative spinal infection, a normal WBC cannot exclude infection; ESR: ESR alone is not specific for the diagnosis of infection and cannot be used as a decisive indicator of infection, but is a relatively sensitive indicator in the inflammatory process and can provide a reliable basis for decision making such as discontinuation of antibiotics;
CRP: probably the most sensitive indicator of postoperative infection, has a pioneering role in clinical forecasting, and is now recognized as a more sensitive systemic indicator of inflammation and tissue damage; in various types of infection, CRP is a more sensitive indicator than WBC or ESR.
Takahashi suggests that persistent lymphocytopenia after lumbar internal fixation fusion may indicate a concurrent infection; acute reactors such as ESR and CRP may correlate with the degree of inflammatory response and the size of the procedure.
The half-life of CRP is 2.6 days, which is relatively reliable and practical. CRP should return to normal 1-2 weeks after surgery, whereas hematocrit may remain elevated for several weeks. When CRP persists at high levels, even in the absence of associated clinical signs or atypical clinical signs, one should be alert to the possibility of infection.