Chapter 29 Orthopedics
Rheumatologic disorders
1. Is rheumatoid arthritis (RA) just a disease of the joints and adjacent connective tissue?
2. What are some of the clinical manifestations of RA?
3. What are some airway abnormalities that can occur in patients with rheumatoid arthritis?
4. Why might the normal mouth opening be decreased in patients with rheumatoid arthritis?
5. What occurs to the developing mandible in patients with juvenile rheumatoid arthritis that makes it more difficult to intubate the trachea in this patient population?
6. What are some of the clinical manifestations of cricoarytenoid arthritis?
7. Can neck movement in patients with RA result in cervical spine injury? What is the clinical implication of this?
8. What percent of patients with RA have involvement of their cervical spine?
9. What are three abnormal movements of the cervical spine that may be manifest in patients with rheumatoid arthritis?
10. What is atlantoaxial subluxation?
11. What pathology in RA patients can lead to atlantoaxial subluxation?
12. How is the degree of atlantoaxial subluxation measured? What is this measurement called?
13. What test can be used to determine the atlas-dens interval?
14. What degree of motion between the atlas and dens, or at what atlas-dens interval, is the patient considered to be at risk for spinal cord injury?
15. In the case of pure transverse axial ligament disruption, does flexion or extension increase the atlas-dens interval?
16. If a patient is asymptomatic with neck flexion and extension preoperatively can the anesthesiologist be reassured of an atlas-dens interval of less than 4 mm?
17. What is subaxial subluxation? What is its clinical significance?
18. What is superior migration of the odontoid? What are the potential clinical manifestations?
19. What is the surgical treatment for superior migration of the odontoid?
20. What effect does rheumatoid arthritis have on the trachea?
21. What is the pathology in ankylosing spondylitis?
22. What is the hallmark neck position in patients with ankylosing spondylitis?
23. Ankylosing spondylitis is associated with which HLA type?
24. What are some considerations for the anesthetic management of patients with ankylosing spondylitis?
Spine surgery
25. What are some considerations for the anesthetic management of patients undergoing spine surgery?
26. What are the various surgical approaches to spine surgery? What are the clinical implications of this?
27. What kind of endotracheal tubes can be employed to provide one-lung ventilation for thoracic spine surgery?
28. What is an advantage of a bronchial blocker to provide one-lung ventilation for thoracic spine surgery?
29. What newer technique do surgeons employ during thoracoscopic spine surgery to move the lung from the operative field that does not require one-lung ventilation?
30. Why is intraoperative awareness a possible complication of spine surgery?
31. Is it mandatory to employ a monitor for intraoperative awareness in patients undergoing spine surgery?
32. Name some methods to help decrease blood loss in a patients undergoing spine surgery.
33. What pharmacologic methods exist to diminish blood loss in patients undergoing spine surgery? Why is aprotinin not used?
34. What are some considerations for patients placed in the prone position?
35. Why is spinal cord integrity monitored during spine surgery?
36. What are various methods used to monitor the spinal cord during spine surgery?
37. What are somatosensory evoked potentials (SSEPs)? What part of the spinal cord do they monitor?
38. What changes in latency and amplitude are considered abnormal when monitoring SSEPs during spine surgery?
39. What anesthetic technique should be employed in patients being monitored with somatosensory and/or motor evoked potentials?
40. What are some surgically related conditions that can interfere with spinal cord monitoring waveform acquisition?
41. Why are some areas of the spinal cord more prone to ischemia?
42. What are some factors that can affect intraoperative spinal cord monitoring waveform acquisition?
43. During spine surgery, what is the time course in which changes in the SSEP waveforms manifest after the loss of spinal cord integrity?
44. What is the appropriate management of a patient during spine surgery once significant changes are noted in the spinal cord monitoring waveforms?
45. What area of the spinal cord is monitored by transcranial motor evoked potentials?
46. How does paralysis with neuromuscular blocking drugs affect transcranial motor evoked potentials?
47. Why might masseter muscle contraction occur during transcranial motor evoked potentials monitoring? What is the clinical implication of this?
48. What special precautions should be taken for patients undergoing transcranial motor evoked potentials monitoring during spine surgery?
49. How are intraoperative electromyelograms used to determine if a pedicle screw has been placed too close to a nerve root?
50. Can neuromuscular blockade be in effect when electromyelograms are being obtained?
51. What is the role of the intraoperative wake-up test?
52. How is an intraoperative wake-up test performed?
53. Name potential complications of the intraoperative wake-up test.
54. What considerations are important at the conclusion of a spine procedure?
55. How can postoperative pain be managed in the patient after spine surgery?
56. Which patients are at the greatest risk of postoperative visual loss? What are some other possible factors that contribute to postoperative visual loss?
57. What are some aspects associated with the prone position that may contribute to postoperative visual loss?
58. How much of postoperative visual loss is due to ischemic optic neuropathy?
59. What are the determinants of the ocular perfusion pressure? What is the clinical implication of this?
60. What intraoperative factors has the American Society of Anesthesiologists (ASA) registry determined to be present in the vast majority of postoperative visual loss patients?
61. According to the ASA practice advisory regarding patients at high risk for postoperative visual loss during spine surgery, is the use of deliberate hypotension associated with postoperative visual loss?
62. According to the ASA practice advisory regarding patients at high risk for postoperative visual loss during spine surgery, what type of fluid should be administered with crystalloid in these cases?
63. According to the ASA practice advisory regarding patients at high risk for postoperative visual loss during spine surgery, is there a defined transfusion trigger at which the risk of postoperative visual loss is eliminated?
64. According to the ASA practice advisory regarding patients at high risk for postoperative visual loss during spine surgery, how should the patient’s head and the operating room table be positioned when the patient is prone?
Surgery in the sitting position
65. What neurologic postoperative complications have been noted in patients who undergo surgery in the sitting position?
66. When devastating neurologic postoperative complications occur after surgery in the sitting position, what is the implicated cause?
67. Is the systemic arterial blood pressure at the level of the heart the same as that at the level of the circle of Willis when patients are anesthetized and placed in the sitting position?
68. What calculation more accurately determines the arterial blood pressure at the level of the circle of Willis when one knows the arterial blood pressure at the level of the heart when patients are anesthetized and placed in the sitting position?
69. What superficial landmark correlates with the circle of Willis?
70. What is the potential risk of hypotension in patients that are anesthetized and placed in the sitting position?
Fractured hip
71. Name several factors that predispose a person to a hip fracture.
72. What is the mortality rate associated with a hip fracture?
73. How do comorbidities in the patient with a fractured hip affect their postoperative outcome?
74. Does it make sense to delay surgery in a patient with a fractured hip and significant comorbidity to improve the patient’s medical status prior to surgery?
75. When should patients with a recent myocardial infarction and a fractured hip be scheduled for surgery?
76. What are some considerations for the anesthetic management of patients undergoing hip surgery?
77. Does choice of anesthetic technique—spinal or general anesthesia—play a role in the outcome of patients who have fractured their hip?
78. What are the pros and cons of regional or general anesthesia in the patient with a fractured hip?
79. How are the elderly affected by the use of narcotics in the perioperative period?
Total joint replacement
80. Use of methylmethacrylate cement is associated with what side effects?
81. What is the etiology of the systemic reaction to methylmethacrylate cement?
82. Which patients are at high risk for a systemic reaction to methylmethacrylate cement?
83. What is an appropriate tourniquet inflation pressure for lower extremity surgery?
84. What is the upper limit of tourniquet time before it should be deflated?
85. If tourniquet time exceeds 2 hours and the procedure is not completed, then the tourniquet should be deflated for how long before it is reinflated and why?
86. What are some complications associated with tourniquet use?
87. When does the major amount of blood loss occur during total knee replacement surgery?
88. What are current recommendations for performing a neuraxial block in patients who received enoxaparin?
89. When can redosing of enoxaparin occur after removal of an epidural catheter?
90. What are the current recommendations for performing a neuraxial block in patients taking clopidogrel?
Answers*
Rheumatologic disorders
1. RA is a chronic inflammatory disease, which initially destroys joints and adjacent connective tissue and then progresses to a systemic disease affecting major organ systems. (499, Figure 32-1)
2. Systemic manifestations of RA are widespread. They may include pulmonary involvement with interstitial fibrosis and cysts with honeycombing, gastritis and ulcers from aspirin and other analgesics, neuropathy, nephropathy, muscle wasting, vasculitis, and anemia. Ultimately the anatomy of the airway is damaged and altered in patients with rheumatoid arthritis. (499, Figure 32-1)
3. Some airway abnormalities that can occur in patients with rheumatoid arthritis include decreased mouth opening, a hypoplastic mandible, cricoarytenoid arthritis, and cervical spine abnormalities. (499-500)
4. Normal mouth opening may be decreased in patients with rheumatoid arthritis as a result of temporomandibular arthritis. (499)
5. The patient with juvenile rheumatoid arthritis often has a hypoplastic mandible as a result of early fusion. This results in the noticeable overbite in some patients with RA. (499)
6. As with other joints, the cricoarytenoid joint may be affected by rheumatoid arthritis. Cricoarytenoid arthritis may result in shortness of breath and snoring. RA patients have been misdiagnosed as having sleep apnea when in fact it they have cricoarytenoid arthritis. Patients with cricoarytenoid arthritis may present with stridor on inspiration. This may present in the postanesthesia care unit (PACU) while the patient is recovering from anesthesia. Acute subluxation of the cricoarytenoid joint, as a result of tracheal intubation, can cause stridor as well, and it is not responsive to racemic epinephrine. (500)
7. Yes, movement of the neck in patients with RA can result in cervical spine injury. The patient must be carefully evaluated for both the complexity and the risk of endotracheal intubation because of difficulty in visualizing the airway as a result of the anatomic changes that occur. Normal endotracheal intubation maneuvers with neck movement may result in an increased risk of cervical spine injury due to destruction of the bones and ligaments of the cervical spine. These can place the cervical spinal cord at risk. Many cervical spine abnormalities may occur in patients with RA. (499)
8. The cervical spine is affected in up to 80% of patients with RA. (500)
9. Three abnormal movements of the cervical spine that may be manifest in patients with rheumatoid arthritis include atlantoaxial subluxation, subaxial subluxation, and superior migration of the odontoid. (500, Figure 32-2).
10. Atlantoaxial subluxation is the abnormal movement of the C1 cervical vertebra (the atlas) on C2 (the axis). (500)
11. Normally, the transverse axial ligament holds the odontoid process, (also referred to as the dens), which is the superior projection of the vertebra of C2, in place directly behind the anterior arch of C1. With destruction of the transverse axial ligament by RA, movement of the odontoid process is no longer restricted. As the neck is flexed and extended, the C1 vertebra can sublux on the C2 vertebra. This can result in impingement of the spinal cord, placing it at risk for damage. (500-501, Figure 32-3)
12. Subluxation of C1 on C2, referred to as atlantoaxial subluxation, can be quantified by a measuring the distance between the back of the anterior arch of C1 and the front of the dens or odontoid. This distance is referred to as the atlas-dens interval. (501)
13. Flexion and extension radiographs of the cervical spine are obtained to determine the distance between the atlas and dens, or the atlas-dens interval, and thus the degree of subluxation. (501, Figure 32-4)
14. If the atlas-dens interval is 4 mm or more atlantoaxial instability is present, the amount of subluxation is considered significant, and the patient is considered to be at risk for spinal cord injury. (501)
15. In a situation in which the transverse axial ligament is disrupted, extension of the neck minimizes the atlas-dens interval and increases the safe area for the spinal cord. Conversely, flexion of the neck increases the atlas-dens interval and decreases the safe area for the spinal cord, making flexion a more frequent risk position. Still, rheumatoid arthritis affects more than just the transverse axial ligament; therefore, all neck movements in patients with rheumatoid arthritis have to be evaluated carefully as extension of the neck can also lead to problems. (501, Figure 32-5)
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