Identification of the neuraxial space by ultrasound in a patient with spinal instrumentation for scoliosis scheduled for total right hip arthroplasty for coxarthrosis.

Abstract

Introduction

Neuraxial anesthesia is the technique of choice in orthopedic procedures of the lower limbs due to its analgesic benefits, rapid recovery, and fewer adverse effects. In patients with scoliosis and prior spinal instrumentation, identifying the subarachnoid space can be technically challenging, often requiring multiple attempts and needle redirections, which may lead to inadequate dispersion of the local anesthetic and result in insufficient or failed block. Ultrasound has emerged as a complementary tool that facilitates localization of the neuraxial space, increasing the likelihood of first-attempt success.

Case Presentation: A 74-year-old female, frail, with avascular necrosis of the right hip and adult degenerative scoliosis, scheduled for right total hip arthroplasty with surgical history posterior thoracolumbar approach, L1–L2 osteotomy, 360° arthrodesis of L4–L5 and L5–S1, and posterolateral fixation from T10 to the iliac bones (April 2025). Comorbidities: type 2 diabetes mellitus (NPH insulin 18 units daily), arterial hypertension (verapamil 80 mg PO every 12 h), peripheral neuropathy (pregabalin 150 mg PO every 12 h), neurogenic bladder, and a history of smoking (quit 20 years ago). Preoperative evaluation: neurologically intact, wheelchair-bound, reporting pain intensity 8/10, managed with a buprenorphine patch 35 mcg initiated one month prior. Physical exam revealed a 20 cm thoracolumbar surgical scar, clean and non-erythematous. Laboratory tests and chest X-ray findings were consistent with her surgical and comorbid history. Classified as ASA II with elevated surgical risk (high ARISCAT and CAPRINI scores).

Anesthetic Plan: Given the anatomical distortion due to the spinal instrumentation, it was decided to perform ultrasound-guided neuraxial anesthesia, with prior informed consent from the patient, ultrasound marking was performed in the L2–L3 intervertebral space and a lateral approach was used, the puncture was successful after two attempts, achieving adequate administration of the local anesthetic and an effective neuraxial block for the surgical intervention. There were no immediate complications related to the anesthetic technique.

Conclusion: This case highlights the usefulness of ultrasound in neuraxial practice for geriatric patients with spinal deformity and instrumentation. Ultrasound facilitates identification of the subarachnoid space, reduces the need for multiple needle redirections, and increases the probability of success, contributing to a safer and more predictable technique in anatomically complex scenarios. Systematic use of ultrasound is recommended in patients with a history of spinal surgery or significant deformity to optimize outcomes and minimize risks.