Ultrasound-Guided Oblique Sagittal Anterior Quadratus Lumborum Block in Total Hip Arthroplasty: A Randomized Controlled Trial.

BACKGROUND: The anterior quadratus lumborum block (QLB) is gaining popularity in total hip arthroplasty (THA) surgeries for postoperative pain management and this technique rarely results in lower limb muscle weakness. However, no studies have described the range of its blockade. OBJECTIVES: The aim of the study was to confirm the range of cold temperature sensory blockades, observe the opioid consumption after THA surgery, assess the pain of the patients, and assess the safety of this technique. STUDY DESIGN: Randomized controlled study. SETTING: Taizhou Hospital of Zhejiang Province. METHODS: Patients who underwent primary THAs were randomized to take an oblique sagittal anterior QLB with 30 mL of 0.375% ropivacaine (QLB+G group) or with 30 mL of 0.9% saline (G group). The main purpose of the study was to confirm the range of cold hypoesthesia. The other aim included the average blood pressure, heart rate, surgical pleth index, and bispectral index values fluctuation during the intraoperative period of expanding the medullary cavity, the sufentanil, and remifentanil consumption during the operation, the amount of time the patients stayed in the Postanesthesia Care Unit, the 8 hours, 16 hours, and 24 hours total dosage of oxycodone, the resting and exercise Visual Analog Scale (VAS) pain scores at 8 hours, 16 hours, and 24 hours after surgery, postoperative adverse events, and safety. RESULTS: The QLB+G group identified areas  of cold hypoesthesia after the block, but there were no areas of cold hypoesthesia in the G group. The consumption of oxycodone in the 8 hours, 16 hours, and 24 hours after the surgery and the consumption of sufentanil during the surgery were significantly smaller in the QLB+G group (P < 0.05). The QLB+G group have lower pain scores at the resting 8 hours and exercise 8 hours, 16 hours, and 24 hours after the surgery (P < 0.05). The 2 groups have comparable safety in the study. LIMITATIONS: This study only tested the areas of cold hypoesthesia after the QLB, but not tested the area of sensory loss. Using ice to test for hypoesthesia is subjective, and may not reflect the actual area of the block. CONCLUSIONS: Ultrasound-guided oblique sagittal anterior QLB can reduce the analgesics required after and during THA and the postoperative VAS pain scores, but it rarely affects muscle strength.