60 patients ASA I-III, undergoing orthopedic surgery will be randomly assigned into one of three groups, namely group A (n=20), where dexmedetomidine will be used for sedation (initial bolus dose followed by continuous infusion), group B (n=20) where midazolam will be used for sedation (initial bolus dose followed by continuous infusion) and group C (n=20), where remifentanil will be used for sedation (initial bolus dose followed by continuous infusion). All patients will receive spinal anesthesia. Duration of postoperative analgesia, total dose of patient controlled IV morphine, sedation scores, nausea and vomiting, time of ambulation, sleep quality and patient satisfaction will be recorded for the first postoperative day. Additionally chronic pain on the site of surgery will be recorded in 3 and 6 months postoperatively.

Inclusion Criteria:

Physical status according to American Society of Anesthesiologists (ASA) I-III Patients scheduled for orthopedic surgery

Exclusion Criteria:

Patient denial, contraindication of spinal anesthesia or any of the agents used in the protocol, BMI above 30, Serious psychiatric, mental and cognitive disorders, Language barrier, illicit substances abuse,