To identify the value of using the ultrasound in applying a commonly used regional anaesthetic procedure (spinal anaesthesia) when compared with the conventional landmark guided approach, regarding the efficiency of the anaesthetic technique, incidence of associated common complications and patient's satisfaction.

Inclusion Criteria:

1. ASA physical status I-II patients
2. Patient's consented approval
3. Males or Females
4. Aged 18-60 years old
5. Body mass index less than 30
6. Scheduled for orthopaedic knee surgeries

Exclusion Criteria:

1. Age less than 18, and more than 60 years
2. Body mass index more than 30
3. Patient refusal or failure to obtain consent
4. Patient in whom spinal anaesthesia is contraindicated (infection at the site of needle insertion, coagulopathy reflected by values of INR≥ 1.2 or platelets count≤ 75.000, or receiving oral anticoagulants)
5. Known sensitivity to local anaesthetics
6. Pre-existing neurological disorder or neuromuscular disease
7. Clinically obvious or known spinal deformity or previous spinal surgery