Efficacy of transcutaneous electrical acupoint stimulation on early mobilisation in patients undergoing unilateral biportal endoscopic discectomy: a study protocol for a randomised controlled trial

Abstract

Background

Early mobilisation represents a core element of enhanced recovery after surgery (ERAS) and is recommended after minimally invasive spine surgery including unilateral biportal endoscopy (UBE). However, strategies to facilitate early mobilisation after UBE remain limited. Transcutaneous electrical acupoint stimulation (TEAS) may improve postoperative pain and recovery after spine surgery, but available evidence in UBE remains inconclusive.

Objective

To investigate whether perioperative TEAS enhances postoperative recovery after UBE.

Methods

This single-centre randomised controlled trial with blinded assessors will enrol 114 patients undergoing elective UBE discectomy. Participants will be randomly allocated (1:1) by simple randomisation to receive stimulation via self-adhesive electrodes, either single-session TEAS at Neiguan, Dazhui, Chengshan and Sanyinjiao initiated 30 min before surgery until the end of the procedure using a disperse–dense waveform (2/100 Hz) with individualised intensity (10–15 mA) or sham stimulation applied at four non-meridian, non-acupoint sites with brief initial stimulation followed by 0 mA output. Standardised general anaesthesia with bispectral index and analgesia nociception index monitoring will be provided following ERAS recommendations. The primary outcome is successful ambulation rate at 6 hour postoperatively; baseline pain, nausea, quality of recovery and functional status will be assessed using the Numerical Rating Scale, Visual Analogue Scale, Quality of Recovery-15 questionnaire, Oswestry Disability Index (ODI) and Japanese Orthopaedic Association (JOA) score at baseline before intervention while postoperative pain, nausea and vomiting, opioid consumption and Quality of recovery will be evaluated at 6, 24 and 48 hours after surgery, with ODI and JOA assessed during longer-term follow-up and surgery-related adverse events monitored postoperatively. Continuous outcomes will be analysed using parametric (repeated-measures analysis of variance) or non-parametric (Mann-Whitney U) tests, and categorical variables using χ² or Fisher’s exact tests.

Ethical considerations and dissemination

This study was approved by the Ethics Committee of Beijing Friendship Hospital (No: 2024-P2-087-01) and registered with Chinese Clinical Trial Registry. Results will be published in peer-reviewed journals.

Trial registration number

ChiCTR2400083344.

STRENGTHS AND LIMITATIONS OF THIS STUDY.

• This will be a prospective, single-centre, single-blind, randomised controlled trial evaluating the effect of transcutaneous electrical acupoint stimulation (TEAS) on postoperative analgesia and early mobilisation after unilateral biportal endoscopy spine surgery.

• The protocol provides detailed descriptions of TEAS timing, acupoint selection and stimulation parameters to ensure clear and repeatable procedures.

• Validated outcome measures, including time to first ambulation and Quality of Recovery-15, will be used to objectively assess postoperative recovery.

• The absence of mechanistic biomarker analysis may limit exploration of the underlying physiological mechanisms of TEAS.

• The single-centre design may limit the application of the findings to other surgical centres.

Introduction

Degenerative lumbar disorders, particularly lumbar disc herniation and lumbar spinal stenosis, are major causes of pain and disability worldwide, with epidemiological data indicating that approximately 10%–40% of patients with lumbar disc herniation and nearly 600 000 elderly patients with lumbar spinal stenosis require surgical intervention in the USA every year.^{1 2} Unilateral biportal endoscopy (UBE) is a novel minimally invasive spine surgery technique that has garnered significant attention because of its advantages of minimal spinal destruction, faster postoperative recovery and shorter hospital stays.^{3 4} As microendoscopic procedures become the main surgical approach for treating degenerative lumbar disorders, the principles of enhanced recovery after surgery (ERAS) have also been recommended and widely adopted in the perioperative management of minimally invasive spine surgery.⁵ Early mobilisation is a core element of spine ERAS protocols and is strongly associated with improved physical functional recovery, better long-term clinical outcomes, shorter hospital stays and lower healthcare costs.⁶ Some studies have shown that the implementation of early ambulation in patients undergoing lumbar fusion surgery can reduce length of hospitalisation and decrease the rate of hospitalisation-related complications by 12.8%–23.7%.7,9 Early ambulation on surgery day has also been demonstrated to yield favourable clinical outcomes and reduce hospitalisation, and 6-hour postoperative ambulation with a lumbar brace was associated with enhanced short-term recovery and earlier resumption of daily activities after percutaneous endoscopic lumbar discectomy (PELD).10,12 However, patients undergoing UBE surgery commonly experience early postoperative functional deficits, such as surgical site pain, transient lower-limb weakness, postoperative nausea and vomiting (PONV), and delayed gastrointestinal recovery, thereby directly compromising their ability to mobilise within the first postoperative hours and potentially delaying implementation of ERAS pathways.¹³ More intense postoperative pain is detected in patients undergoing UBE, which substantially hinders early ambulation on the day of surgery.¹⁴ Although potent rapid-acting analgesics, including opioids, non-opioid agents and adjuvants, are routinely administered to control post-UBE pain, analgesic-related side effects may still occur and remain an important contributor to delayed ambulation time and reduced patient satisfaction.^{15 16} At present, consensus on standardised mobilisation protocols and effective strategies to optimise perioperative analgesia remains limited, which poses a significant barrier to consistent early mobilisation practices and may compromise postoperative recovery. Therefore, developing interventions that optimise analgesia and facilitate early mobilisation after UBE surgery is required.

Conventional transcutaneous electrical nerve stimulation is a widely used non-invasive analgesic technique that delivers electrical currents to symptomatic areas for pain relief.¹⁷ As a modern, non-invasive adaptation of traditional Chinese acupuncture, transcutaneous electrical acupoint stimulation (TEAS) applies electrical stimulation to predefined acupuncture points instead of symptomatic areas, thereby distinguishing this approach from conventional transcutaneous electrical nerve stimulation and aiming to modulate peripheral and central pathways involved in pain and postoperative recovery.¹⁸ Several studies have demonstrated that perioperative TEAS can effectively relieve postoperative pain, lower the risk of PONV and improve overall postoperative recovery in heterogeneous surgical procedures including abdominal, gynaecological, orthopaedic and knee replacement surgeries.19,21 Meanwhile, TEAS has been applied in open spine surgery and shown to have an association with effective postoperative pain control and reduction in the occurrence of PONV and postoperative cognitive dysfunction.^{22 23} However, current evidence specifically evaluating interventions for postoperative pain after UBE is limited, and the impact of such interventions on early ambulation after lumbar discectomy or minimally invasive spine surgery has been insufficiently explored. To address this gap, we designed this single-blind, randomised controlled trial to evaluate whether the preventive intervention of TEAS at specific acupoints can exert an analgesic effect and promote early mobilisation after UBE spine surgery.

Methods and analysis

Trial design

This prospective, single-centre, single-blind randomised controlled trial will include patients scheduled for UBE discectomy at Beijing Friendship Hospital, Capital Medical University. Participants will be randomly allocated in a 1:1 ratio to receive either active TEAS or sham stimulation. Screening will be conducted as stated in the well-prepared criteria and preliminary protocol. All relevant information will be collected and recorded throughout the study, the in-hospital postoperative period and the scheduled long-term follow-up (figure 1). This study protocol is reported in accordance with the Standard Protocol Items: Recommendations for Interventional Trials 2013 Statement, and the final trial report will adhere to the Consolidated Standards of Reporting Trials (CONSORT) 2010 guidelines.^{24 25} A CONSORT flow diagram summarising participant enrolment, randomisation, follow-up and analysis is provided in figure 2.

Figure 1. Standard Protocol Items: Recommendations for Interventional Trials Schedule for enrolment, interventions and assessments.JOA, Japanese Orthopedic Association score; ODI, Oswestry Disability Index; PONV, postoperative nausea and vomiting; QoR-15, Quality of Recovery-15; Sham, sham stimulation; T1, 30 min before surgery; T2, at the beginning of surgery; T3, at the end of surgery; T4, 6 h after surgery; T5, 24 h after surgery; T6, 48 h after surgery; T7, discharge; T8, 1 week after discharge; T9, 1 month after discharge; T10, 3 months after discharge; T11, 6 months after discharge; T12, 1 year after discharge; TEAS, transcutaneous electrical acupoint stimulation; UBE, unilateral biportal endoscopy.

Figure 2. CONSORT flow diagram. CONSORT, Consolidated Standards of Reporting Trials; JOA, Japanese Orthopaedic Association; ODI, Oswestry Disability Index; QoR-15, Quality of Recovery-15; UBE, unilateral biportal endoscopy.

Sample size calculation

In line with the previous study that has adopted 6-hour postoperative ambulation as a clinically relevant target,¹⁰ the sample size calculation in the present trial was based on the primary outcome, defined as the proportion of patients achieving successful ambulation at 6 hours after surgery. According to our pilot data, the expected ambulation rate was approximately 70% in the experimental group and 40% in the control group, yielding an absolute effect size of 30%. With a two-sided alpha level of 0.05 and a statistical power of 80%, a minimum of 52 participants was required in each group. After accounting for an anticipated dropout rate of 10%, the total sample size was set at 114 participants, with 57 patients allocated to each group. This allowance was primarily intended to ensure completeness of primary outcome ascertainment, as the primary outcome is assessed at a predefined inpatient time point during hospitalisation with a lower risk of missing data.

Grouping, randomisation and blinding

This is a single-blind trial. Outcome assessors and data analysts will be blinded to group allocation. Additionally, outcome assessors will not have access to intraoperative anaesthesia records or TEAS treatment logs. Due to the characteristics of the intervention, the acupuncturists administering TEAS and the anaesthesiologists involved in intraoperative management will be aware of treatment allocation but will not participate in postoperative outcome assessment or data analysis. Although participants will receive identical-appearing electrode patches in both groups to enhance blinding credibility, they will not be formally considered blinded. All TEAS electrodes will be removed before postoperative assessment, and assessors will be instructed not to discuss intraoperative management with participants. Randomisation will be conducted using a computer-generated block code. According to a 1:1 allocation ratio, consecutive participants will be randomly assigned to either the control group or the experimental group. Allocation codes will be prepared by an independent research nurse and concealed in sequentially numbered, opaque, sealed envelopes. For each eligible participant, the next envelope in sequence will be opened by the nurse immediately before intervention, and the participant will be assigned accordingly. Blinding will be maintained throughout the trial unless unblinding is required for patient safety. The original data were all collected on a case report form and any inadvertent unblinding will be documented.

Study participants and recruitment

Patients scheduled to undergo selective UBE discectomy will be recruited from Beijing Friendship Hospital affiliated with Capital Medical University. Recruitment will be initiated through the display of informational posters in hospital outpatient clinics. Clinicians will introduce the trial procedures to patients during routine consultations and perform eligibility screening based on predefined inclusion and exclusion criteria. Only patients meeting all eligibility criteria will be enrolled in the trial. We enrolled the first patient on 6 June 2024, and plan to complete enrolment by 6 June 2026. All participants will sign the informed consent form documents to be involved in this clinical trial, allowing the data to be collected and analysed by the researchers.

Inclusion criteria and exclusion criteria

Inclusion criteria: (1) Aged 18–75 years, diagnosed with lumbar disc herniation or lumbar spinal stenosis according to established clinical guidelines, and scheduled for UBE lumbar discectomy, regardless of sex^{26 27}; (2) 18 kg/m²≤body mass index≤30 kg/m² (body mass index=weight in kilograms/height in metres squared); (3) American Society of Anesthesiologists physical status classification I–III and (4) Participants voluntarily agree to participate and sign an informed consent.

Exclusion criteria: (1) patients undergoing cervical or thoracic spine surgery; (2) local acupoint skin infection; (3) pre-existing limb nerve injury; (4) enrolment in any other clinical trial during the preceding 4 weeks; (5) unable to reply or use pain assessment such as Numeric Rating Scale (NRS) and Visual Analogue Scale (VAS) scores; (6) implanted with a pacemaker; (7) suspected or confirmed pregnancy; (8) opioid addiction or current utilisation of central analgesics; (9) presence of severe neurological or psychiatric comorbidities and (10) any other condition deemed unsuitable for study participation.

Post-enrolment exclusion and withdrawal criteria

Participants may be excluded from further study participation or withdrawn after enrolment under the following circumstances: (1) withdrawal of informed consent by the participant at any time during the study, without the need to provide a reason; (2) occurrence of major protocol deviations that may compromise the validity of the study results, such as incorrect intervention allocation or failure to receive the assigned intervention; (3) inability to complete key outcome assessments due to intercurrent medical conditions or unexpected clinical events unrelated to the intervention and (4) loss to follow-up, defined as inability to establish contact with the participant despite reasonable and documented attempts. Data collected up to the time of withdrawal will be retained for analysis in accordance with the intention-to-treat principle and the approved ethics protocol, unless the participant explicitly requests removal of the data.

Safety monitoring and discontinuation criteria

All TEAS-related or anaesthesia-related adverse events will be recorded, including skin erythema or blistering, intolerable local pain (NRS≥4 despite rescue analgesia), dizziness, palpitations, nausea or vomiting, or haemodynamic instability as defined in the anaesthesia protocol. Surgery-related adverse events, including cerebrospinal fluid leakage and postoperative bleeding, will be monitored from ward admission to 48 hours postoperatively. TEAS will be discontinued if any adverse event occurs or at the participant’s request, and participants will be withdrawn in the event of serious adverse events, protocol violations, or if continuation is deemed unsafe by the attending anaesthesiologist or spine surgeon. All adverse events will receive appropriate medical evaluation and management and will be documented for analysis.

Intervention

To promote postoperative recovery and ensure consistent perioperative management across both groups, all patients will receive a standardised anaesthesia regimen and ERAS protocol based on the Consensus statement for perioperative care in lumbar spinal fusion.²⁸ Pre-operative education regarding the surgical procedure and recovery expectations will be provided on admission. Oral celecoxib 100 mg and pregabalin 75 mg will be administered 2 hours before surgery, with fasting restricted to 6 hour for solids and 2 hours for clear fluids.

Standard monitoring, including electrocardiography, non-invasive blood pressure, pulse oximetry, bispectral index (BIS) and analgesia nociception index (ANI), will be applied after arrival in the operating room. General anaesthesia will be induced with midazolam 0.03 mg/kg, sufentanil 0.3–0.4 µg/kg, etomidate 0.1–0.3 mg/kg and rocuronium 0.6–0.8 mg/kg, followed by tracheal intubation and mechanical ventilation. Anaesthesia will be maintained using continuous infusions of propofol and remifentanil (0.07–0.2 µg/kg/min), titrated to maintain BIS values between 45 and 55 and ANI between 50 and 70, with end-tidal CO₂ controlled at 35–45 mm Hg. All anaesthetic agents will be discontinued after skin closure. Haemodynamic management will follow a predefined protocol, with atropine 0.25–0.5 mg intravenous for bradycardia (heart rate <50 beats/min), esmolol 0.2–0.5 mg/kg intravenous for tachycardia (heart rate >100 beats/min) and ephedrine 6 mg intravenous for hypotension (mean arterial pressure <65 mm Hg or >20% decrease from baseline lasting >3 min). For preventive analgesia, flurbiprofen 50 mg intravenous will be administered 30 min before the end of surgery. After extubation, patients will be transferred to the post-anaesthesia care unit for continued monitoring. Sedation will be assessed using Modified Observer’s Assessment of Alertness/Sedation score and shivering will be graded using a standard 4-point shivering scale in PACU and within 6 hours postoperatively.

Acupuncture protocol

The experimental group: TEAS will be applied to patients at three symmetrical bilateral acupoints, including Neiguan (PC6, figure 3A), Chengshan (BL57, figure 3C) and Sanyinjiao (SP6，figure 3D), and an unpaired midline acupoint Dazhui (DU14, figure 3B). Before electrode attachment, the skin over all stimulation sites will be cleansed with 75% isopropyl alcohol swabs and allowed to dry naturally to reduce skin–electrode impedance. Self-adhesive electrodes will then be applied bilaterally to the four predefined acupoints and connected to a HANS acupoint nerve stimulator (Nanjing Jisheng Medical Technology, Nanjing, China), which delivers an alternating disperse–dense waveform at 2/100 Hz (alternating every 3 s). Stimulation intensity will be gradually increased prior to surgery to determine each participant’s maximum tolerated level (10–15 mA). The exact current value was recorded for each session and continuous stimulation will subsequently be delivered intraoperatively at the individualised intensity. All TEAS interventions will be delivered by licensed and certified acupuncturists with a minimum of 5 years of clinical experience who have received standardised pretrial training in acupoint localisation, stimulation parameters, electrode placement, intensity adjustment and safety procedures. Each participant will receive a single perioperative TEAS session, initiated 30 min before surgery and continued throughout the operative procedure. The detailed stimulation parameters and acupoint locations of the TEAS are summarised in figures3 4.

Figure 3. The location of acupoints in the experimental group. (A) Neiguan (PC6); (B) Dazhui (DU14); (C) Chengshan (BL57); (D) Sanyinjiao (SP6).

Figure 4. The detailed parameters of TEAS. TEAS, transcutaneous electrical acupoint stimulation.

The control group: two control points are placed near HT7 (Shenmen), specifically at locations 7 and 9 cun proximal and 1 cun lateral to the original point (figure 5A); the location at 9 and 12 cun above BL60 (Kunlun) is another two control points (figure 5B). Self-adhesive electrodes are applied to these sham acupoints, which are not located on any meridian and are not connected to an active nerve stimulator. The electrode patches will be connected to the acupoint nerve stimulator with a visible connection to the patient. An initial brief stimulation at the patients’ maximum tolerated intensity will be delivered for 5–10 s to induce a transient sensory perception, after which the output will be reduced to 0 mA (no electrical current delivered) to maintain the sham condition. The simulation period initiates prior to 30 min before the onset of UBE surgery and continues throughout the procedure, identical in timing to the experimental group.

Figure 5. The location of acupoints in the control group. (A) Two control points located near HT7 (Shenmen), positioned 7 and 9 cun proximal and 1 cun lateral to the original acupoint; (B) Two control points located 9 and 12 cun above BL60 (Kunlun).

The intervention will be discontinued during the treatment period if participants experience severe adverse events or if their symptoms resolve completely. To promote participant adherence and ensure completion of scheduled follow-up during the intervention period, researchers will provide detailed instructions regarding study procedures, expectations for compliance and follow-up arrangements. Clear communication of required actions and their rationale will be emphasised to enhance participant understanding and engagement throughout the intervention and follow-up period. Outcome assessors, data collectors and study coordinators will receive unified training before study initiation, covering standardised procedures for early ambulation assessment, pain and nausea evaluation, functional outcome scoring and case report form completion. Inter-rater agreement will be assessed during pilot evaluations, and regular data monitoring and cross-checking will be conducted to minimise recording errors and maintain data integrity.

Outcomes assessment

All clinical outcomes will be collected by a trained monitor from the Data Monitoring Committee (DMC) after surgery. The primary outcome in the trial is the successful proportion of ambulation at 6 hours after UBE surgery.²⁹ At 6 hours postoperatively, patients will be instructed by an assessor to attempt ambulation. Successful ambulation is defined as the patient’s ability to independently transfer from the bed and walk approximately 2 m to a chair placed beside the bed without physical assistance, in accordance with a previous study. Prior to assessment, the assessor will confirm patient safety, including stable vital signs, adequate consciousness (MOAA/S≥4) and the absence of severe dizziness or nausea. Ambulation will be evaluated in a standardised ward environment. Verbal instructions are permitted; however, any requirement for physical assistance such as supporting body weight, lifting or guiding limbs will result in the attempt being recorded as unsuccessful. Accordingly, if a participant is unable to attempt ambulation for predefined safety reasons, the outcome will be prespecified and recorded as ‘unsuccessful ambulation’ instead of being treated as missing data. Secondary outcomes include postoperative pain, nausea severity, opioid consumption, Quality of Recovery (QoR-15), functional disability (Oswestry Disability Index, ODI), functional status (Japanese Orthopaedic Association, JOA), and surgery-related adverse events, all assessed during the postoperative period. Postoperative pain intensity will be assessed using the 11-point NRS, which has been widely used in postoperative lumbar discectomy cohorts and has demonstrated construct validity through correlation with functional outcomes.³⁰ Postoperative nausea severity will be measured using a 0–100 mm VAS, a quantitative tool that has been shown to be reliable and responsive for assessing subjective postoperative symptoms, including nausea intensity, in multimodal perioperative recovery studies.³¹ Postoperative opioid consumption will be recorded and converted to morphine milligram equivalents (MME), a standardised and reproducible metric, which has been widely used as an outcome measure in lumbar spine surgery studies to quantify analgesic requirements.³² The quality of postoperative recovery will be evaluated using the QoR-15 questionnaire, a patient-reported outcome measure that has demonstrated applicability and responsiveness in patients undergoing degenerative lower back procedures.³³ Functional disability will be assessed using the ODI, a disease-specific instrument with proven internal consistency and psychometric validity in patients undergoing surgery for lumbar degenerative disorders.³⁴ Functional status will also be evaluated using the JOA score, a clinician-rated scale that has been widely accepted for assessing postoperative improvement after spinal procedures, with changes in JOA scores shown to correlate with patient-reported recovery.³⁵

A single 1 mg intravenous bolus of morphine will be administered as rescue analgesia when patients report intolerable pain or when the NRS pain score is ≥4, and repeated if necessary. A 5-HT3 receptor antagonist will be administered when the nausea VAS score is ≥40 mm or when vomiting occurs. Baseline assessments of pain, nausea, QoR-15, ODI and JOA scores will be performed prior to the initiation of TEAS. Sedation level will be assessed in the post-anaesthesia care unit. Anaesthesia-related indicators, including intraoperative opioid consumption, perioperative cardiovascular events and time to awakening and recovery, will be recorded intraoperatively and during the immediate recovery period. Early postoperative outcomes, including postoperative pain, PONV, consumption of rescue analgesic medication and QoR-15, will be evaluated during hospitalisation at 6, 24 and 48 hours after surgery. Long-term functional outcomes of the lumbar spine will be assessed using ODI and JOA at 1 week, 1 month, 3 months, 6 months and 12 months after surgery. To minimise dropouts, primary and secondary outcomes are assessed during hospitalisation and synchronised with routine postoperative care. Participants will be informed of study procedures in advance, and assessments will be performed by trained staff at predefined time points. All analyses will follow the intention-to-treat principle.

Statistical analysis and variable evaluation

All analyses will be conducted using SPSS (V.22.0) based on the Full Analysis Set according to the intention-to-treat principle. Normality will be assessed using the Shapiro-Wilk test. The primary outcome, successful ambulation at 6 hours postoperatively, will be reported as absolute risk differences with Newcombe 95% CIs and as risk ratios with log-transformed 95% CIs. Adjusted risk ratios will be estimated using log-binomial regression, with modified Poisson regression with robust standard errors applied if convergence fails. Models will be adjusted for sex, age, body mass index and postoperative opioid consumption within the first 6 hours expressed as MME and MME per hour. Sensitivity analyses will be performed in the per-protocol set. Between-group differences in MME and MME/hour will be analysed using generalised linear models with a gamma distribution and log-link, with adjusted effect estimates and 95% CIs reported. Repeated-measures continuous secondary outcomes (including postoperative pain scores, QoR-15, ODI and JOA) will be analysed using repeated-measures analysis of variance with group as the between-subject factor and time as the within-subject factor. Sphericity will be evaluated using Mauchly’s test, with Greenhouse-Geisser correction applied when violated. Homogeneity of variance will be assessed using Levene’s test. Non-parametric tests (Mann-Whitney U or Wilcoxon signed-rank test) will be used when assumptions are not met. Categorical variables will be analysed using the chi-square test or Fisher’s exact test as appropriate. All tests will be two-sided with p<0.05 considered statistically significant. Safety analyses will be conducted in the Safety Set.

Data collection and monitoring

The DMC is composed of an anaesthesiologist responsible for information gathering, a scientific researcher and a specialist in statistics. The specialised anaesthesiologist from the DMC will note the true enrolled number of participants, the number of exclusions, demographic and other basic characteristics, incidence of complications and relevant treatment, and comprehensive efficacy evaluation. The description of demographic characteristics, medication history and therapy history of the patients will also be noted, including the comparison of age, gender, disease course and disease condition at the time of enrolment. Interim analysis and unblinding will be performed and evaluated by the DMC, independent of competing interests and the sponsor. DMC has the right to decide whether to continue the trial, modify the protocol or terminate the clinical trial through communication with Institutional Review Boards. At the end of the study, the distribution information, the original data and calculated results will be saved by the scientific research management committee, which is responsible for the final trial dataset; all the relevant data will be confidentially preserved from the public until the results are published.

Discussion

In this randomised controlled trial, the effect of perioperative TEAS compared with sham stimulation on early mobilisation and postoperative recovery in patients undergoing UBE spine surgery will be evaluated. Early mobilisation is a critical component of the spine ERAS pathway and is closely associated with improved functional status, fewer postoperative complications and shorter hospital stays.^{36 37} Yu et al¹⁰ have implemented ambulation 6 hours after surgery as a standard ERAS component in inpatient models of PELD and further explored the feasibility of earlier mobilisation, as early as 2 hour postoperatively, in a day-surgery setting. Despite the recognised relevance of early mobilisation, the successful implementation of early mobilisation at 6 hour in routine clinical practice remains challenging due to early postoperative pain, which is a common non-lethal adverse event and a major cause of delayed mobilisation and reduced patient satisfaction.^{38 39} Considering that opioids remain a cornerstone of multimodal analgesia and are frequently prescribed after discharge, regional techniques such as the erector spinae plane block have been demonstrated as a meaningful analgesic technique after UBE surgery, contributing to opioid-sparing effects and a reduction in opioid-related adverse events.39,42 Nevertheless, the widespread clinical application of nerve blocks remains limited by concerns regarding potential infection risk and dependence on clinician expertise, and thus highlights the need to explore effective opioid-sparing strategies to optimise postoperative pain control and facilitate early ambulation after UBE surgery.

Prior multimodal clinical studies have identified acupuncture stimulation as an effective and safe adjunct for reducing intraoperative anaesthetic requirements,⁴³ providing early postoperative pain relief, lowering the incidence of postoperative adverse events^{20 21 44} and accelerating patient recovery.¹⁹ Compared with pharmacological analgesia and regional anaesthesia techniques, TEAS is a non-invasive intervention which can be feasibly applied without disrupting routine clinical procedure during the perioperative period.²² A recent meta-analysis of randomised controlled studies reported that TEAS mainly induces mild and transient adverse events, such as local skin irritation or discomfort at electrode sites, with no increase in serious perioperative complications.⁴⁵ Other available evidence also suggests that perioperative TEAS is well tolerated in patients undergoing spine surgery, with no TEAS-related serious adverse events reported and no increase in perioperative haemodynamic instability or postoperative complications compared with sham or control interventions.⁴⁶ Yao et al⁴⁷ have also demonstrated that TEAS used as part of multimodal analgesia can not only effectively alleviate postoperative pain but also shorten the time to ambulation. The clinical evidence that perioperative TEAS is associated with reduced postoperative pain scores and analgesic consumption at multiple early postoperative time points, including within the first 6 hours after surgery, supports the selection of the 6-hour time point as a clinically relevant assessment time point for capturing the intervention effect. These findings all support the favourable safety profile of TEAS and justify the application in the clinical practice. The positive effects of TEAS on early mobilisation and postoperative recovery may involve multiple neurophysiological and humoral mechanisms. Electrical stimulation at PC6 and SP6 has been reported to activate endogenous opioid pathways and descending inhibitory systems, facilitating the release of β-endorphins and enkephalins in the central nervous system, modulating vagal afferents and central pain-processing regions.⁴⁸ In contrast, stimulation at BL57 and DU14 may potentially participate in pain modulation through peripheral, spinal and central pathways, without being linked to a specific confirmed circuit.⁴⁹ Above all, these mechanisms may inhibit nociceptive transmission and alleviate postoperative pain, which is expected to reduce postoperative opioid requirements and may correspond to the MME and MME/h assessed in this study.

In addition, TEAS can regulate autonomic nervous system balance through enhancing parasympathetic activity and suppressing excessive sympathetic responses. Particularly, stimulation at PC6 has been demonstrated to modulate vagal tone and the chemoreceptor trigger zone, thereby reducing the incidence of PONV.²¹ Such autonomic modulation may also improve gastrointestinal motility and attenuate nausea and vomiting responses, providing a physiological basis for improvements in postoperative VAS nausea scores, recovery of gastrointestinal function and overall QoR-15 scores. Stimulation at DU14 and BL57 may improve local microcirculation and neuromuscular excitability in the lumbar and lower-limb regions, which may facilitate early muscle activation and reduce fatigue during mobilisation.⁵⁰ These effects may potentially contribute to a higher success rate of early ambulation or a shorter time to first ambulation.

Overall, this study is designed to determine whether perioperative TEAS can provide postoperative pain relief and enhance recovery in patients undergoing UBE spine surgery, exploring a more feasible opioid-sparing strategy and objective measures to support ERAS implementation in UBE spine surgery. As this study is conducted at a single centre, the findings may have limited generalisability to other clinical settings, and complete blinding of the therapists delivering TEAS is not feasible. In addition, the primary outcome focuses on early ambulation, and longer-term functional outcomes will require further investigation.

Ethics and dissemination

Ethical approval was obtained in accordance with national regulatory requirements and the Declaration of Helsinki. This study was approved by the Ethics Committee of Beijing Friendship Hospital, Capital Medical University, China (Approval No: 2024-P2-087-01). Patients were enrolled after registration in the Chinese Clinical Trial Registry. The results of this study will be disseminated through publication in peer-reviewed international journals and presentations at national and international academic conferences. Study findings will also be shared with relevant clinical departments within the hospital to facilitate the translation of evidence into clinical practice.

Confidentiality

Participant data will be stored using coded identifiers during data collection and analysis. No personally identifiable information will be disclosed in any publications or presentations resulting from this study.

Trial status

This trial is currently in the recruitment phase. Patient enrolment commenced on 6 June 2024 and is scheduled to end on 6 June 2026. At the time of manuscript submission, recruitment was ongoing and data analysis had not yet started.

The funding agent plays no role in study design, data collection, data analysis, data interpretation, writing of the report, or submission of the report as an article for publication.