The Sacral Erector Spinae Plane Block in Total Knee Arthroplasty

Total Knee Arthroplasty (TKA) is a common orthopedic surgery in elderly patients, often requiring effective postoperative pain control to enhance recovery. Conventional locoregional techniques include adductor canal block (ACB) and the iPACK block (infiltration between the Popliteal Artery and Capsule of the Knee). While effective, iPACK may carry infection risks due to its proximity to the surgical field.

The sacral ESP block is a more recent ultrasound-guided technique targeting posterior sacral nerve branches from a remote site, potentially avoiding motor weakness and surgical site complications. Early literature and local clinical experience suggest that combining sacral ESP with ACB may provide comparable analgesia to ACB+iPACK while offering practical and safety advantages.

Study Design:

• Type: Single-center, prospective, observational study
• Setting: Ospedale di Crotone, Italy
• Duration: Maximum of 30 months
• Sample size: 63 patients per group (based on QoR-15 score, with 80% power and α = 0.05)

Population:

• Adults >18 years (ASA I-III), scheduled for unilateral TKA with expected hospitalization >24 hours
• Exclusion: refusal of consent, contraindications to spinal or regional anesthesia, coagulation disorders, severe dementia, ongoing infection, or emergency surgeries

Primary Endpoint:

• Quality of Recovery (QoR-15) score at 24 hours post-surgery (score range 0-150; higher scores indicate better recovery)

Secondary Endpoints:

• Postoperative pain scores (NRS, score range 0-10, higher scores indicate more pain) at rest and movement (0-48 hours)
• Time to first mobilization
• Patient satisfaction (Likert scale)
• Analgesic consumption and time to first request
• Incidence of nausea, vomiting, antiemetic use
• Block-related complications or adverse events

Procedure:

All patients receive spinal anesthesia and multimodal postoperative analgesia (paracetamol, rescue tramadol). Regional blocks are performed under ultrasound guidance in aseptic conditions. ESP is performed at the S2 level with 20 mL ropivacaine 0.375%. ACB and iPACK are also administered per standard protocols.

Data Analysis:

Statistical comparisons between groups will be made using appropriate parametric or non-parametric tests based on variable distribution. Repeated measures will be analyzed using linear mixed-effects models.

Ethics:

The study follows Good Clinical Practice (GCP) and the Declaration of Helsinki. Patients provide written informed consent. Privacy and data confidentiality are ensured.

Inclusion criteria

• Adults >18 years
• ASA I-III
• scheduled for unilateral TKA with expected hospitalization > 24 hours

Exclusion criteria

• Refusal of consent
• Local anesthetics allergies
• contraindications to spinal or regional anesthesia
• coagulation disorders
• anticoagulation/antiaggregation medications
• dementia
• ASA-PS > III
• ongoing infection
• emergency surgeries