Combined spinal epidural anaesthesia is the preferred choice for anaesthesia in knee arthroplasty patients. Lumbar neuraxial procedures are typically performed via a blind surface landmark and palpation technique. The success depends on good knowledge of anatomy and skills due to its complexity. Patient factors such as obesity, abnormal spinal anatomy or previous spine surgeries result in increased failure rate of neuraxial blockade. The intercristal line/ Tuffiers line determined by palpation may not be a reliable landmark for fourth and fifth lumbar interspace in neuraxial anaesthesia. Lumbar spinous process increases significantly in both length and width with ageing, which makes epidural anaesthesia technique challenging through midline in geriatric population in whom majority of knee replacement surgeries are done. Neuraxial ultrasonography in epidural space identification is a recent development and has shown to improve the success rate of neuraxial blockade and can reduce the risk of failed or traumatic lumbar punctures and epidural catheterizations. The use of preprocedural ultrasound has been shown to increase first pass success rate in thoracic epidural catheter insertion and spinal anaesthesia in patients with difficult surface landmarks. Therefore, this prospective, randomised study has been designed to assess the ease of insertion and its success rate after identification of the relevant landmarks using ultrasound as compared to traditional palpation of bony landmarks.