Study design
We performed a retrospective analysis of a prospectively established database of DSD. The ethics committee of our hospital approved the study (permit data 2018.4.3; no. 2018086). We reviewed the consecutive patients who underwent open correction surgery for DSD between August 2016 and February 2022. Inclusion criteria included age greater than 50 years and open correction surgery for degenerative spinal deformity. The exclusion criteria were: 1) revision surgery; 2) concomitant cervical spine surgery; 3) non-contiguous segmental surgery; 4) drug treatment for cancer; 5) incomplete postoperative information; 6) cognitive impairment; 7) neoplasm, infective damage to the vertebral structure. Applying ERAS in clinical practice is a process of continuous learning and improvement. Although the ERAS protocol was initially introduced at our center in January 2019, the full implementation of the ERAS program began in July 2019. Therefore, the ERAS group consisted of patients who underwent surgery from August 2019 to January 2022, and the control group consisted of patients from August 2016 to December 2021.
ERAS protocol
Our ERAS pathway includes preoperative, intraoperative, and postoperative multimodal management by a multidisciplinary team (Fig. 1). This protocol was implemented at our center after receiving institutional approval.
Multidisciplinary assessment and preoperative optimization
Preoperative multidisciplinary evaluation is the cornerstone of our ERAS program, which helps to predict the risk of perioperative adverse events and treat chronic disease. The spinal surgeon determines the severity of spinal deformities and the location of nerve compression and vertebral instability based on the symptoms and preoperative imaging. The spine surgery team then carries out the procedure plan. Based on the patient's laboratory test results and previous medical history, an internist evaluates the patient for severe chronic diseases, including coronary heart disease and hematologic diseases. Blood glucose and blood pressure levels are monitored and stabilized one week before surgery. Nutritionists perform preoperative nutritional evaluations using a nutritional screening scale and instruct patients to adjust their diet to improve preoperative nutrition. Psychologists assess the patient's mental status and provide psychological support if needed. A rehabilitation physician evaluates the patient's physical function and daily activity ability before surgery. Smokers are referred to a smoking cessation clinic one month before surgery, and opioid-dependent patients are referred to a chronic pain service center. Anesthesia-related risks are evaluated by senior anesthesiologists using the American Society of Anesthesiologists grade and the age-adjusted Charlson Comorbidity Index [10]. All evaluations results are collected preoperatively and used to guide surgical decision-making and perioperative interventions.
Education and consultation
Patients are educated on evaluating the degrees of pain using a numerical rating scale and Oswestry Disability Index. Expectation management includes patient education regarding the variability in pain improvement after fusion surgery. Patients are educated on the importance of physical rehabilitation and non-narcotic medication administration. Our center offers a multifaceted consulting service for patients with degenerative spinal deformity. The first-round consultation is conducted to determine patient expectations and inform patients regarding the surgical procedure and the possibility of perioperative adverse events. A geriatric consultation is provided for older patients. Patients with frailty and other systemic degenerative disorders (e.g., osteoporosis, Parkinson, and depression) are referred to corresponding clinics. A senior anaesthesiologist conducts a preoperative consultation regarding the adequate preoperative preparation and general anesthesia. All patients undergo live or online preoperative courses on upper and lower extremity strength exercises, lumbar back muscle exercises, and roll-over exercises in bed.
Optimized preoperative preparation
In patients undergoing elective DSD surgery, prolonged fasting predisposes to increased surgical stress response and surgery-induced insulin resistance. The preoperative preparation of the ERAS pathway requires cessation of clear liquids for two hours, and solid foods for eight hours before anesthesia. Other preoperative preparations include the administration of an oral carbohydrate-rich drink two hours before surgery and avoiding using mechanical bowel preparation. Establishing intraoperative blood pressure goals, maximum allowable blood loss and transfusion triggers are also essential in optimizing preoperative preparation.
Intraoperative management
The ERAS pathway includes multimodal analgesia, continuous monitoring, minimizing blood loss and operative time, and consistent members of operating room. Patients in the ERAS group were administered oral pregabalin two hours before surgery. All patients received general anesthesia with intravenous propofol and remifentanil according to weight and operation time. A mixture of 10 ml 2% lidocaine and 10 ml 1% ropivacaine was infiltrated around the surgical incision before incision and after skin closure. Intraoperative monitoring focuses on blood pressure, urinary volume, neurophysiological monitoring, and blood loss. Patients without contraindications were routinely given intravenous antifibrinolytics (tranexamic acid) to reduce blood loss. Applying topical hemostatic material and blood pressure control were also important interventions to control intraoperative bleeding. All DSD surgeries were performed by the same operating room staff, including a surgeon, anesthesiologist, and circulating nurse, contributing to reduced operation time. Unless extubation failed, the patients routinely returned to the ward after surgery.
Postoperative management
The post-operative ERAS protocol includes multimodal pain management, early removal of urinary tube and drainage tube, preventing and treating complications, and early recovery of physiological function. Multimodal pain management involves a combination of acetaminophen, steroids, gabapentin, pregabalin, cyclooxygenase-2 inhibitors, and neuraxial anesthesia with different mechanisms of action to reduce the use of opioids and optimize pain control. The urinary tube (if placed) was routinely removed within 72 h after surgery, except in rare cases. Unless complications occur, the drainage tube is removed within 96 h after surgery. From postoperative days 0 to 3, anti-vomiting drugs and gastric mucosal protective agents are routinely infused intravenously to alleviate adverse reactions in the gastrointestinal tract. Antithrombotic prophylaxis includes on-bed movement, early off-bed mobilization, lower extremity pneumatic pump application, and compression stocking placement. For patients with histories of hypercoagulable or thrombophilic clotting abnormalities, low molecular weight heparin is injected subcutaneously every 24 h for four to five days. Early recovery of physiological function involves improving physical function and early recovery of gastrointestinal function. All patients are encouraged to ambulate on postoperative day 1 with the assistance of nursing staff and start physical exercise from postoperative day 0 with the guidance of a rehabilitation physician. Other ERAS protocol items include early oral fluid and food intake after surgery, nutritional support, early intravenous fluids discontinuation, and oral administration of docusate suppository if no bowel movement occurs within 48 h after surgery.
Data collection
From a prospectively established database, we extracted demographic data (age, gender, body mass index [BMI], payer status, comorbidities, chronic opioid use), preoperative radiographic parameters (lumbar lordosis [LL], sagittal vertical axis [SVA], pelvic tilt [PT], thoracic kyphosis [TK], pelvic incidence [PI] and pelvic incidence minus the lumbar lordosis angle [PI-LL], thoracolumbar kyphosis [TLK]), and surgery-related variables (operative time, operating room duration, estimated blood loss, number of fused levels, laminectomy, and interbody fusion). To control for differences in baseline data, ERAS patients were 1:1 propensity-score matched to a historical cohort by the same surgical team based on age, gender, BMI, and the number of levels fused. LOS was the primary outcome measure. Physiological functional outcome indicators such as time to first bowel movement, first ambulation, and days of urethral indwelling catheter were assessed as secondary outcome measures. We also compared the rates of complications and readmissions between the two groups within 90 days after surgery.
Statistical analysis
Continuous variables were expressed as mean ± standard deviation and analyzed using the two-tailed Student’s t-test or Mann–Whitney U-test as appropriate. Categorical variables were expressed as frequencies with percentages and analyzed using Fisher’s exact or chi-square tests. All statistical analyses were performed using SPSS Statistics 25 (SPSS, version 22.0, Inc., Chicago, IL, USA). Statistical significance was set at p < 0.05.