title: Differences in short-term complications between spinal and general anesthesia for primary total knee arthroplasty.
abstract: BACKGROUND
  Spinal anesthesia has been associated with lower postoperative rates of deep-vein thrombosis, a shorter operative time, and less blood loss when compared with general anesthesia. The purpose of the present study was to identify differences in thirty-day perioperative morbidity and mortality between anesthesia choices among patients undergoing total knee arthroplasty.
  
  
  METHODS
  The American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database was searched to identify patients who underwent primary total knee arthroplasty between 2005 and 2010. Complications that occurred within thirty days after the procedure in patients who had been managed with either general or spinal anesthesia were identified. Patient characteristics, thirty-day complication rates, and mortality were compared. Multivariate logistic regression identified predictors of thirty-day morbidity, and stratified propensity scores were used to adjust for selection bias.
  
  
  RESULTS
  The database search identified 14,052 cases of primary total knee arthroplasty; 6030 (42.9%) were performed with the patient under spinal anesthesia and 8022 (57.1%) were performed with the patient under general anesthesia. The spinal anesthesia group had a lower unadjusted frequency of superficial wound infections (0.68% versus 0.92%; p = 0.0003), blood transfusions (5.02% versus 6.07%; p = 0.0086), and overall complications (10.72% versus 12.34%; p = 0.0032). The length of surgery (ninety-six versus 100 minutes; p < 0.0001) and the length of hospital stay (3.45 versus 3.77 days; p < 0.0001) were shorter in the spinal anesthesia group. After adjustment for potential confounders, the overall likelihood of complications was significantly higher in association with general anesthesia (odds ratio, 1.129; 95% confidence interval, 1.004 to 1.269). Patients with the highest number of preoperative comorbidities, as defined by propensity score-matched quintiles, demonstrated a significant difference between the groups with regard to the short-term complication rate (11.63% versus 15.28%; p = 0.0152). Age, female sex, black race, elevated creatinine, American Society of Anesthesiologists class, operative time, and anesthetic choice were all independent risk factors of short-term complication after total knee arthroplasty.
  
  
  CONCLUSIONS
  Patients undergoing total knee arthroplasty who were managed with general anesthesia had a small but significant increase in the risk of complications as compared with patients who were managed with spinal anesthesia; the difference was greatest for patients with multiple comorbidities. Surgeons who perform knee arthroplasty may consider spinal anesthesia for patients with comorbidities.
authors.affiliation: Department of Orthopaedic Surgery, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, 01008 JPP, Iowa City, IA 52242, USA.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Pugely
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Martin
authors.forename: Yubo
authors.initials: Y
authors.lastname: Gao
authors.forename: Sergio
authors.initials: S
authors.lastname: Mendoza-Lattes
authors.forename: John J
authors.initials: JJ
authors.lastname: Callaghan
mesh_terms: D000368:Aged; D000768:Anesthesia, General / Q000009:adverse effects*; D000775:Anesthesia, Spinal / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000401:mortality; D015897:Comorbidity; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D015999:Multivariate Analysis; D011183:Postoperative Complications / Q000453:epidemiology* / Q000401:mortality / Q000517:prevention & control; D012189:Retrospective Studies; D012307:Risk Factors; D014481:United States / Q000453:epidemiology