Spinal anaesthesia involves the use of small amounts of local anaesthetic injected into the subarachnoid space to produce a reversible loss of sensation and motor function. Spinal anaesthesia is often used for orthopaedic surgery especially in lower limb surgeries. However, because of the high prevalence of hypotension and bradycardia risk is always there especially in elderly age group because of their compromised haemodynamic status. If it was possible to limit anaesthesia for the surgical field, certain undesirable effects of spinal anaesthesia could be avoided. a conventional unilateral spinal anaesthesia technique can only result in a motor hemiblock and a sensory block preferential to one side but achieving unilaterality is not an easy task as numerous factors come into play.