Vagus Nerve Stimulation as An Adjunct in Postoperative Rehabilitation After Knee Arthroplasty: A Case Report

Vagus nerve stimulation (VNS) has established applications in neurology and rheumatology due to its analgesic and antiinflammatory properties mediated by the cholinergic antiinflammatory reflex [1, 2]. Preclinical and early clinical studies indicate potential benefits in musculoskeletal and perioperative settings [3-7]. However, reports on its use in orthopaedic rehabilitation are scarce. We present a case demonstrating adjunctive taVNS during postoperative rehabilitation after total knee arthroplasty (TKA).

A 67-year-old woman (BMI 29, medical history: left total hip arthroplasty in 2019, hypertension) presented with persistent pain and delayed wound healing three weeks after right TKA. Pain was rated VAS 8/10, and she required 40 mg/day oxycodone. Clinical findings included livid wound edges and serous discharge without signs of infection.

As part of the rehabilitation programme, taVNS was applied using a commercially available auricular stimulation system (25 Hz, pulse width 250 µs, patient-adjusted intensity, 30 minutes/session, five sessions per week for four weeks). Standard physiotherapy, lymphatic drainage, and multimodal pharmacological analgesia continued.

• Week 2: Pain decreased (VAS 5), oxycodone reduced to 20 mg/day. • Week 3: Pain improved to VAS 4, no rescue analgesics required. • Week 5: Complete wound closure, pain reduced to VAS 2, opioid-free. • Adverse events: None.

Table 1 summarises the clinical course. Figure 1 illustrates the reduction in pain and opioid consumption.

Table 1: Timeline of clinical course showing pain (VAS), oxycodone dose, and wound status.

This case suggests that adjunctive taVNS can reduce pain, decrease opioid requirements, and accelerate wound healing in postoperative rehabilitation after TKA. These findings align with preclinical and pilot clinical studies reporting VNS-mediated suppression of pro-inflammatory cytokines and enhanced microcirculation [1-4, 8, 9]. Of particular relevance is the marked reduction in opioid use, a key challenge in postoperative pain management. Similar findings have been reported in recent clinical studies investigating taVNS for acute postoperative pain [5-7]. The progressive wound closure observed in our patient is consistent with experimental evidence that VNS can promote tissue repair and bone remodelling [8-10].

Limitations of this case include its single-patient nature, lack of biomarker monitoring, and potential placebo effects. Nonetheless, the absence of adverse events and the clear clinical improvements support the feasibility of integrating taVNS into orthopaedic rehabilitation.

Transcutaneous auricular vagus nerve stimulation may represent a safe and practical adjunct in postoperative orthopaedic rehabilitation. Controlled clinical trials are warranted to determine its role, optimal parameters, and patient selection criteria.

Ethics approval and consent to participate: Not required for a single case report in accordance with institutional and national guidelines.

Consent for publication: Written informed consent for publication of clinical details and images was obtained from the patient.

Availability of data and materials: Not applicable.

Competing interests: The authors declare no competing interests.

Funding: We acknowledge support by the Open Access Publication fund of medical faculty of the Otto-von-GuerickeUniversity Magdeburg.

Authors’ contributions: C.R. managed the patient and drafted the manuscript. M.F. performed the literature review. C.R. and M.L. contributed to manuscript revision. All authors approved the final version.

The authors thank the rehabilitation team for their support.

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