Use of Preoperative Lumbosacral Spine X-rays in Developing a Predictor Score for Facilitating Neuraxial Blocks in Patients undergoing Lower Limb Arthroplasty Surgeries: A Cross-sectional Study

Abstract

Introduction: Due to bony changes and narrow lumbar interspinous spaces, performing a neuraxial block becomes difficult in older patients undergoing lower limb arthroplasties. Aim: To formulate a difficulty predictor score (MUSG score) for anticipating difficult Central Neuraxial Blocks (CNB) and to compare lumbar spine radiological findings with clinical findings. Materials and Methods: A cross-sectional study was conducted on 166 patients admitted for knee or hip arthroplasties from March 2023 to March 2024 in the main operation theatre complex of a tertiary care hospital. All patients were advised to get X-rays of the lumbosacral spine in both anteroposterior and lateral views before surgery. The total difficulty predictor score was calculated from the X-rays based on the presence or absence of scoliosis, bony osteophytes, angulation of spinous processes, calcification of the ligamentum flavum, and the ratio of inner and outer visible interspinous space. The minimum score was 5 and the maximum was 12. The individual score at each interspinous level was calculated and selected the space with the minimum score for the CNB. A comparison was also made with the clinically selected best space, which was identified using the traditional palpation technique. A block was labeled difficult if there were more than two attempts for spinal and epidural block, respectively. All collected data were entered into a Microsoft Excel sheet and analysed using Microsoft Excel software. Results: The study patients had a mean age of 59.83 years. The total difficulty predictor score (MUSG Score) of the lumbar spine was 5 in 3 patients (1.8%), 6-9 in 140 patients (84.3%), and ≥10 in 23 patients (13.9%). However, the minimum score at the best interspinous space was 5 in 15 patients (9%), 6-9 in 151 patients (91%), and none had a score of 10 or more. From radiological imaging, the spaces with minimal scores were in the order of L2-L3 (76), L3-L4 (62), and L1-L2 (28); while on clinical examination, they were – L2-L3 (96), L3-L4 (43), L1-L2 (23). The difference between the two was statistically significant (p-value <0.05). The time required for the block procedure was longer in patients with a score of 6-9 (13.99 minutes) than in those with a score of 5 (11.13 minutes). Haemodynamic changes from baseline were also more pronounced in patients with a score of 6-9 compared to those with a score of 5. Conclusion: CNBs in patients undergoing hip and knee arthroplasties are easier to perform with the help of the difficulty predictor score (MUSG Score). A difficulty predictor score of 5 is associated with an easier block compared to higher scores.

Keywords

• anteroposterior
• lateral
• physical
• radiological