| Complication Class | Defined Criteria |
| I | None recorded |
| II | Superficial infection, urinary tract infection, Seizure, Transfusion, Venous thromboembolism, Pneumonia |
| III | Wound dehiscence, Neurologic deficit, System sepsis, Reoperation, Readmission, Pulmonary embolism |
| IV | Reintubation, Coma, Septic shock, Implant failure, Cerebrovascular accident |
| V | Death |