A 46-year-old male (body weight 69 kg, ASA status II) was scheduled for right total hip arthroplasty (THA). He suffered from ankylosing spondylitis for 20 years. Physical examination indicated that the cervical and lumbar spine was rigid and the right hip joint was immobilized. The bamboo-like changes of spine were found in the spinal anterioposterior and lateral radiographs (Fig. ). X-ray and CT examination indicated degenerative osteoarthrosis of bilateral hip joints and sacroiliitis on the right side. The patient appeared potentially difficult to be intubated as the examination of airway revealed that the interincisor distance was 2 cm and a Mallampati class III. The preoperative visual analog scale (VAS) score of this patient was 4. This patient received ultrasound-guided lumbar SNRB plus T12 paravertebral and sacral plexus blocks, and 25 mL of 0.4% ropivacaine was used. Pinprick test was used to confirm the success of these blocks. The time of surgery was 1 hour and 26 minutes. He also did not complain any painful during surgery and in PACU. With the PCA, the postoperative VAS scores were 0 to 1. This patient discharged on the second day after surgery. No postoperative complication was reported with him.
Case 2: A 61 years old male (weight 75 kg, ASA status III) suffered from AS for 20 years, and was scheduled for left total hip arthroplasty (THA). He had a history of coronary heart disease and received coronary stent implantation 7 years ago. A physical examination revealed rigidity of cervical and lumbar spine, severe press pain and immobilization of left hip joints. An X-ray of the neck, chest and lower back revealed bamboo-like changes of the spine. CT of the hip joints reported necrosis of the left femoral head, and ankylosis of left hip joint. He had taken aspirin for anticoagulation therapy for a long term, and was replaced by low molecular weight heparin.