Preop US-Guided Nerve Blocks for Pain & Recovery After Ankle Arthroscopy

Effects of Preoperative Ultrasound-Guided Popliteal Sciatic and Saphenous Nerve Blocks on Early Pain and Functional Recovery After Ankle Arthroscopy: A Randomized, Double-Blind, Controlled Trial

This randomized, double-blind controlled trial investigates the effectiveness and potential trade-offs of preoperative ultrasound-guided popliteal sciatic and saphenous nerve blocks in patients undergoing ankle arthroscopy, a procedure often performed in day-case settings but associated with significant early postoperative pain and frequent opioid use. The study evaluates whether these nerve blocks can reduce early postoperative pain-measured by the highest NRS score within 24 hours-and examines their impact on functional recovery, including motor strength and ambulation. All patients receive standardized general anesthesia and multimodal analgesia, with outcomes including opioid consumption, ankle weakness, patient satisfaction, range of motion, muscle strength, hospital stay duration, and analgesia-related costs.

Background

Ankle arthroscopy is often performed in day-case or short-stay settings. Despite the minimally invasive incisions, patients frequently experience significant early postoperative ankle pain, often requiring substantial opioid analgesia, which can lead to notable opioid-related side effects. Currently, there is no standardized perioperative analgesic protocol for this procedure, and high-quality evidence is lacking on whether nerve blocks offer a meaningful net benefit in this context.

This study evaluates the net clinical benefit of preoperative popliteal sciatic and saphenous nerve blocks in ankle arthroscopy by assessing their effect on early postoperative pain control and functional mobility. Outcomes are measured through the highest pain scores within 24 hours and assessments of ambulation ability, aiming to inform clinical decision-making regarding perioperative analgesia strategies.

Hypothesis

Compared to sham blocks, preoperative popliteal sciatic and saphenous nerve blocks significantly reduce the highest postoperative pain scores (NRS 0-10) in the recovery room after ankle arthroscopy, but may also result in reduced ankle motor strength and decreased early ambulation ability.

Surgical and Anesthetic Protocol

All patients receive general anesthesia, maintained with propofol and remifentanil according to body weight. Anesthetic depth is titrated to maintain a BIS value between 40-60 while ensuring hemodynamic stability. A standardized dose of 5 mg of tropisetron is administered postoperatively to prevent PONV.

Postoperative analgesia includes celecoxib 200 mg BID and acetaminophen 500 mg every 6 hours, with oxycodone-acetaminophen (325 mg/5 mg) available as rescue analgesia if needed.

Outcome Measures

Highest NRS pain score within 24 hours postoperatively

Total opioid consumption in the first 24 hours

Average pain score at 24 hours post-op

Patient-reported ankle weakness (NRS 1-10)

Patient satisfaction with postoperative analgesia (4-point Likert scale)

Degrees of ankle plantarflexion and dorsiflexion, and MRC muscle strength grading (0-5), assessed pre-block and at discharge

Total hospital stay duration

Total costs related to anesthesia and analgesia

Inclusion Criteria:

Age between 18 and 65 years

ASA physical status classification I-II

Scheduled to undergo ankle arthroscopy under general anesthesia

Expected to be available for follow-up on the day of surgery (day-case or short-stay surgery)

Able to understand the procedures and methods of the clinical trial and voluntarily provide written informed consent

Body mass index (BMI) between 16 and 32 kg/m²

Exclusion Criteria:

History of severe ankle nerve injury or peripheral neuropathy

Severe cardiac, pulmonary, hepatic, or renal dysfunction

Chronic pain or regular use of opioid analgesics for more than 3 months

History of extensive ankle or lower leg surgery that may affect nerve localization

Psychiatric disorders or cognitive impairment that preclude accurate NRS pain scoring

Pregnancy or breastfeeding

Known allergy or contraindication to any of the study drugs

Any other condition deemed unsuitable for inclusion by the investigators