Due to an increasingly ageing population, the number of elderly who need surgical treatment under spinal anaesthesia is increasing(1,2). The mean age for spinal anaesthesia cohort for hip fracture repair demonstrated an increasing trend over time whereas the mean age of the general anaesthesia cohort did not. Studies have shown that the risk of many urinary system diseases( such as benign prosthatic hyperplasia, bladder tumours, urethral strictures) increase drastically with ageing. (3,4) Compared to general anaesthesia spinal anaesthesia has been recognised as providing greater haemodynamic stability, higher patient satisfaction, lower rate of opioid use, higher rate of opioid free recovery and lower maximum post anaesthesia care unit (pacu) pain scores.(4) Due to degeneration of the lumbar spine (bone hyperplasia, ligament calcification, intervertebral space stenosis, spinous process hyperplasia, etc) spinal anaesthesia in elderly patients might be difficult.(8-9) Multiple needle attempt may lead to a higher incidence of complications(post dural puncture headache, paraesthesia, hematoma and infection) increased patient discomfort and dissatisfaction. 

There are two traditional techniques for spinal anaesthesia ( midline technique and paramedian technique) each of which has some advantages and disadvantages in terms of operation and application. Lots of anaesthesiologists proceed through paramedian approach because this approach bypasses most of the bony structures that may impede the advancement of the needle in midline approach. However, paramedian approach requires a sharpened three-dimensional insight as compared to the midline approach. We would encounter inferior articular processes and pedicle more close to needle pathway and less interlaminar foramen diameter in three dimensional structure especially in obese patients.(8)  Therefore, a new approach , the modified paramedian approach using the ultrasound guidance may improve success rate and decrease practice attempts and patient complications.

The purpose of the study is to explore the feasibility of ultrasound assisted modified paramedian technique for spinal anaesthesia in elderly when compared to midline and paramedian approach.

The Null Hypothesis of the study is that there will be no differences in first attempt success rates using ultrasound guidance for spinal anesthesia in elderly for midline , paramedian and modified paramedian approaches.

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