In this study, we examined 215 patients to investigate the use of the ERAS protocol in adult spinal deformity surgery. As a result, we found that postoperative length of stay, postoperative complication rate, recovery of physiologic function, and 90-day readmission rates were significantly reduced in patients after implementing the ERAS protocol.

The purpose of ERAS protocols is to achieve fewer postoperative adverse events and the occurrence of postoperative complications by effectively reducing surgical stress reactions [10], which is important for patients undergoing long-segment fusion surgery. Surgical treatment is extremely important for adult spinal deformity [11]. In a retrospective study by Adeyemo EA et al., the authors examined 124 patients who had undergone thoracolumbar fusion surgery. The results of the study showed an effective reduction in opioid consumption (248.05 vs. 314.05 MED), urinary retention (5.97% vs. 19.3%), and severe constipation (1.49% vs. 31.57%) in patients after thoracolumbar fusion surgery when the ERAS protocol was implemented [6]. This was also confirmed in our study, where the implementation of the ERAS protocol was effective in reducing the incidence of complications such as urinary retention. Compared to short-segment fusion surgery and minimally invasive foramen fusion surgery, patients who undergo long-segment fusion surgery spend a long time lying down postoperatively, which is more likely to promote thrombus formation and increase the risk of thromboembolism and pulmonary complications [12]. Early postoperative training is considered extremely effective in preventing thromboembolism and pulmonary complications. It also significantly reduces the rate of postoperative complications in long-segment fusion surgery [13]. This was confirmed by the results of our study, in which the incidence of postoperative deep vein thrombosis was significantly reduced after the implementation of the ERAS protocol (7.8% vs. 1.8%, P = 0.005). Previous studies have shown that the prognosis of spinal deformity surgery is influenced by several factors such as comorbidities and malnutrition [14, 15]. In elderly patients, comorbidities increase the difficulty of spinal deformity surgery, decrease the postoperative recovery of the patient’s physiological function, and increase the risk of postoperative complications [16]. At the same time, the number of fused segments involved in long-segment fusion operations increased significantly, requiring decompression and intradiscal fixation, and the number of segments treated during surgery increased the damage to paraspinal muscles and microvessels, resulting in significant increases in the extent of intraoperative blood loss and operative time as well as the likelihood of postoperative wound and urinary tract infections compared to minimally invasive and short-segment fusion surgeries [17, 18]. In a study by Le Huec et al., the authors describe a protocol for reducing perioperative blood loss in complex spinal surgeries. This study found that reducing perioperative blood loss significantly reduced the need for postoperative blood transfusion and postoperative complications [19]. In our study, our findings further revealed a marked reduction in the volume of intraoperative blood loss, and a notably lower proportion of patients requiring postoperative blood transfusions in the ERAS cohort compared to the non-ERAS group. Forthermore, we found that the incidence of postoperative wound infections, urinary tract infections, and nausea and vomiting were significantly higher in the pre-ERAS group compared with the ERAS group. Multifactorial logistic regression analysis of the incidence of postoperative complications also revealed that ERAS and urinary catheter removal were significant predictors.

In the study by Porche K et al., the length of hospital stay after implementation of the ERAS protocol in thoracolumbar fusion surgery ranged from 4.8 days before ERAS to 3.8 days after ERAS. In the current study, we found that there was no significant difference between the two groups in terms of total hospital stay, but in terms of postoperative hospital stay, the ERAS group was significantly lower than the pre-ERAS group. We believe that this outcome is closely related to appropriate preoperative optimization, aggressive postoperative nutritional supplementation, and early ground exercise [20]. In a retrospective study by Puvanesarajah V et al. [21], malnutrition was shown to be a significant predictor of increased risk of postoperative infection and wound dehiscence. The patient’s nutritional status is an important factor in the breakdown and weakening of skeletal muscles, and malnutrition significantly increases postoperative complications and mortality, and also significantly increases the length of hospital stay. In the results of this study, postoperative complications were found to be a significant risk factor for prolonged postoperative hospital stay after multivariate regression analysis of LOS. In our study, we found no significant difference in preoperative hemoglobin and albumin levels between the two groups. However, patients in the postoperative pre-ERAS group had significantly higher postoperative blood and albumin transfusions than those in the ERAS group. Due to the active postoperative fluid management and postoperative nutritional supplementation in the ERAS group, although the hemoglobin level in the ERAS group was slightly lower than that in the pre-ERAS group on the first postoperative day, it was still slightly higher in the ERAS group than in the pre-ERAS group at the time of discharge. Regarding the postoperative albumin levels of the two groups, the albumin mean level of the pre-ERAS group was below 30 g/L on the first postoperative day according to the criteria for postoperative albumin supplementation in our department, and there was no significant difference in the albumin levels of the two groups at the time point discharge from hospital after infusion [22]. Therefore, we can conclude that active postoperative fluid management and timely postoperative nutritional supplementation according to ERAS protocol may effectively reduce patients’ postoperative hemoglobin and albumin intake rates. This may reduce the frequency of postoperative complications and postoperative LOS [23]. Whether effective supplementation of preoperative and postoperative nutritional status in adult spinal deformity surgery effectively shortens the length of hospital stay and the incidence of postoperative complications requires further study.

Although it is known that getting out of bed early may help restore physiological functions after surgery, patients’ out-of-bed early execution is low due to the large postoperative incisions in long-segment fusion surgery [24]. Currently, there is some research on early postoperative motor rehabilitation after long-segment fusion surgery for adult spinal deformity [25]. Some studies have shown that preoperative pre-rehabilitation in patients with adult spinal deformity may effectively reduce the promotion of recovery of postoperative motor function. In a retrospective study by Nielsen et al., the authors specifically investigated preoperative pre-rehabilitation [26]. In this study, the pain and intensity of preoperative low back pain were significantly reduced in patients who received pre-rehabilitation and early rehabilitation. At the same time, the authors found a significant reduction in the length of hospital stay in patients who had undergone pre-rehabilitation, from 7 days to 5 days. Pre-rehabilitation performed before surgery in patients with poor organic function may effectively increase the likelihood of surgical success. Therefore, for adult patients with spinal deformity due to their poor physical function and major surgical trauma, to reduce the occurrence of postoperative side effects and ensure the recovery of physiological function, preoperative pre-rehabilitation should be performed to effectively encourage patients to leave the bed in the early postoperative period. At the same time, we advocate for patients to remove the drainage tube and urinary catheter as soon as possible. We have found that early removal of the urinary catheter may effectively reduce the incidence of postoperative complications. Early removal of the drainage tube may effectively shorten the postoperative hospital stay, promote the recovery of the patient’s physiologic function, and reduce the patient’s 90-day readmission rates.

In contrast to conventional treatment, in which patients are fasting preoperatively and postoperatively, the ERAS protocol emphasizes early postoperative nutrition [27]. Very early nutritional intake promotes recovery of gastrointestinal function, which may effectively reduce the incidence of postoperative nausea and vomiting [28]. In this study, there is a significant difference in postoperative nausea and vomiting between the two groups of patients (22.5% vs. 8.8%, P = 0.005). Traditional preoperative fasting in nursing has been shown to cause electrolyte disturbances and postoperative insulin resistance in patients, thereby increasing the incidence of postoperative complications such as delirium and cardio-cerebral disease, as well as patient mortality. In the present study, the incidence of postoperative delirium in the pre-EARS group was not statistically significantly different from that in the ERAS group but was still significantly higher than in the EARS group. This suggests that shortening the preoperative fasting period to promote early postoperative nutrition in the ERAS group may be effective in improving the occurrence of postoperative complications. In recent years, a growing number of studies have begun to analyze the elements of ERAS protocols and whether the same outcomes can be achieved by implementing some elements of ERAS interventions [29], such as preoperative education, multimodal analgesia, early bed discharge, and early rehabilitation. Thus, neglecting adherence to ERAS protocols reduces the impact of ERAS protocols on the postoperative period. Bisch SP et al. showed that patients who adhered to at least 80% of the ERAS protocols had significantly fewer complications than patients who adhered to less than 80% [30]. For each additional element of the ERAS protocols, there was an 8% reduction in length of stay for low-complexity procedures and a 12% reduction in length of stay for moderate/high-complexity procedures. The results of our study showed that due to high patient compliance on admission, preoperative and intraoperative management was significantly better adhered to than postoperative management, but overall adherence to the ERAS regimen was still over 95%. This was also confirmed by our results, which showed a significant reduction in postoperative complications, length of hospital stay, and 90-day readmission rates in the ERAS group compared with the pre-ERAS group of patients after the implementation of a full ERAS protocol. Therefore, more cross-team collaboration is needed to effectively improve adherence to the ERAS protocol.

This study still has some limitations. Firstly, the two cohorts were in separate periods, possibly resulting in selection bias. In addition, differences in outcomes across inclusion periods may be influenced by various other factors, including technological advances, therapies, and overall medical knowledge. Since it is a retrospective study, all observational data in this study were collected during the hospital stay, and there is a lack of long follow-up data in the later period, which does not fully reflect the effectiveness of ERAS protocols in adult spinal deformity surgery. At the same time, we lack preoperative functional assessment of patients’ frailty and nutritional status, which may hurt prognosis.